Understanding nace mr0175 limits on nickel by Charlie Chong

NACE MR0175 Limits on 1% Nickel Literature search & the official answer referable

Rosafendi/ Charlie Chong

Contents: -

The NACE MR0175 limitation on 1%Ni What some experts said about the NACE MR0175, 1% Ni Max limitations? The â&#x20AC;&#x153;Officialâ&#x20AC;? answer to the MR0175, 1% Ni limitation What if I still want to use material/ welding consumable with >1% Ni for NACE MR0175 compliances? Could I used stress relieve PWHT in lieu to SCC qualification testing for NACE MR0175 compliances on materials with >1% Ni? What if I do not want to perform SCC qualification testing for my refinery piping aimed for Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments? What is Nickel alloy for in low alloy steel? What is Retained Austenite which Nickel believe to promote in low alloy steel? More Reading

Rosafendi/ Charlie Chong

According to MR0175, alloy steel with more than 1% nickel is not allowed even if hardness is less than 22 HRC. Why? Knowing the reasons behind the limitation. - Rosafendi

ISO 15156-2, 7.2.1.4.

Rosafendi/ Charlie Chong

Some Expert Said I am not a member of the committee that developed this standard. Nickel does two things to ferrous-based materials - it increases ferrite strength, increases hardenability and toughness. The increase in toughness is good. Increased hardenability and increased ferrite strength will result in increased hardness of weld heat affected zones in base material containing over 1% nickel. This plays a significant role in trying to keep hardness below a threshold to avoid SCC in service.

Is this your reasoning too? http://www.eng-tips.com/viewthread.cfm?qid=320591

Rosafendi/ Charlie Chong

Some Expert Said blacksmith37 (Materials) 18 Jul 13 17:13 In the 70's and after, there were a few failures of 43XX alloys (and weldments) in H2S. Some failures could be attributed to Ni/Mn segregation causing a lowered critical temp. some were caused by imperfect HT temps or only a single temper cycle . A variety of testing was sponsored by Inco and then NiDi (Dr Bruce Craig ). The data could never convince the MR 01-75 committee that Ni was safe. Note, OCTG grades T95, C105,C110, (sour service) use very low limits on Ni and Mn and use very high tempering temps like 1400F.

Is this your reasoning too? http://www.eng-tips.com/viewthread.cfm?qid=340976

Rosafendi/ Charlie Chong

The Correct Answer

Rosafendi/ Charlie Chong

2.1.2 Materials Grades and Product Forms: Carbon and low-alloy steels in the forms of plate and linepipe comprised the bulk of the materials tested. Continuous cast and control-rolled steels were included. Welds were primarily single-sided submerged-arc or shielded-metal arc. The effect of phosphorus segregation in the grain boundaries was investigated in both low-strength carbon steel and in high-strength low-alloy steels. For many years, controversy has existed concerning nickel content of the steel to the extent that NACE MR0175/ISO 1515611 limited nickel content to a maximum of 1%. Several investigations suggested that the effect of nickel is related to the potential resultant microstructure (i.e., retained austenite that transforms to untempered martensite) and its high susceptibility to SSC. Additionally, cold working has generally been found to decrease SSC resistance, particularly in amounts greater than 5% strain.

Rosafendi/ Charlie Chong

For many years, controversy has existed concerning nickel content of the steel to the extent that NACE MR0175/ ISO 1515611 limited nickel content to a maximum of 1%. Several investigations suggested that the effect of nickel is related to the potential resultant microstructure (i.e., retained austenite that transforms to untempered martensite) and its high susceptibility to SSC.

Rosafendi/ Charlie Chong

What if I still need to used base metal or consumable with Ni>1%

Rosafendi/ Charlie Chong

Hi Luke, ANSI/NACE MR0175/ISO 15156-2:2009, Clause A.2.1.4 allows the following:Welding consumables and procedures that produce a deposit containing more than 1 % mass fraction nickel are acceptable provided successful weld SSC qualification by testing in accordance with Annex B (of MR 0175/ISO 15156) is met. However the default rule is also 1% Max Nickel in the weld metal, as described in many welding consumable manufacturer's consumable specification sheet. Apparently few years ago TWI intiated the following Group Sponsored Project(see the atatchment), titled as : "Raising the Acceptance Level for Nickel in C-Mn Welds for Sour Service". If the other members could shed some lights on this subject it would be very well appreciated. Thanks. Pradip Goswami,P.Eng.IWE Welding & Metallurgical Specialist Ontario, Canada. ca.linkedin.com/pub/pradip-goswami/5/985/299

Rosafendi/ Charlie Chong

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Could I use SR (Stress Relieve) in accordance with ISO 15156-2 sub clause A2.1.4 in lieu of SSC qualification for weldment >1%Ni?

Rosafendi/ Charlie Chong

Question: ISO 15156-2 sub clause A2.1.4 Welding has the following two paragraphs: “Carbon steel and low-alloy steel weldments that do not comply with other paragraphs of this sub clause shall be stress-relieved at a minimum temperature of 620 °C (1150 °F) after welding. The maximum weld zone hardness, determined in accordance with 7.3, shall be 250 HV or, subject to the restrictions described in 7.3.3, 22 HRC”. “Welding consumables and procedures that produce a deposit containing more than 1 % mass fraction nickel are acceptable after successful weld SSC qualification by testing in accordance with Annex B”. Based on this, I interpret the requirements as follows: If there are weldments with Ni contents greater than 1% mass fraction, they can be accepted if the weld procedures are successfully tested to SSC qualification in accordance with Annex B. Alternately, weldments with Ni contents greater than 1% mass fraction shall be acceptable if stress-relieved at a minimum temperature of 620 °C (1150 °F) after welding. The maximum weld zone hardness, shall be 250HV or 22 HRC in that case. Please can you confirm the interpretation. Answer: The intent of the next to last paragraph in A.2.1.4 (15156-2, Annex A) dealing with the 620 °C (1150 °F) SR option does not negate the requirement in the following paragraph which requires SSC qualification testing regardless of SR if the weld deposit is >1% Ni. This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.4 Reference: ISO 15156 Maintenance Panel Inquiry #2013-07

Rosafendi/ Charlie Chong

https://oilandgascorrosion.com/faqwd/mp2013-07/

Could I use SR (Stress Relieve) in accordance with ISO 15156-2 sub clause A2.1.4 in lieu of SSC qualification for weldment >1%Ni?

Rosafendi/ Charlie Chong

What if I do not wish to Perform Qualification test and still need to use Material >1%Ni

Rosafendi/ Charlie Chong

Current NACE Specifications on SSCC NACE MR0175/ISO 15156 – 2009 Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas Production - PART 1 - General principles for selection of cracking-resistant materials - PART 2 - Cracking-resistant carbon and low-alloy steels, and the use of cast irons - PART 3 - Cracking-resistant CRAs (corrosion resistant alloys) and other alloys NACE MR0103 – 2012 Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments

Rosafendi/ Charlie Chong

Some notable material requirements of MR0103 MR-103 does not have specific restriction on maximum nickel content for base metals and welding consumables. http://www.eng-tips.com/viewthread.cfm?qid=342674

Rosafendi/ Charlie Chong

Nickel in Low Alloy Steel What it does?

Rosafendi/ Charlie Chong

Nickel in Low Alloy Steel : Low Alloy Low Temperature Service Steel is formed by adding 2.5% to 3.5 % of Ni in the carbon steel to enhance its low temperature toughness. Ni can strengthen ferrite matrix while lowering Ar3 (third transformation temperature) which helps with fine grain formation. In addition to the normalizing treatment during the production process of low alloy low temperature service steel, quenching and tempering are also parts of the mechanical properties improvement treatment. Stabilizing austenite: Elements such as nickel, manganese, cobalt, and copper increase the temperatures range in which austenite exists.

Omar AbuBakar/ Charlie Chong

http://www.goodweld.com.tw/upload/product/th-18.pdf

What is Retained Austenite?

Rosafendi/ Charlie Chong

What is Retained Austenite Austenite is a face centered cubic (FCC) phase present in steel at high temperature. Upon cooling, most of the steel is transformed into ferrite - a body centered cubic (BCC) phase, or into martensite - a body centered tetragonal (BCT) phase. Depending on the rate of cooling some percentage of the steel (typically 0-30%) will remain as austenite. http://www.protoxrd.com/retained-austenite-info.html

Rosafendi/ Charlie Chong

More Reading

Rosafendi/ Charlie Chong

Item No. 21307

International Standard ANSI/NACE MR0175/ISO 15156-1:2015

Reference number ANSI/NACE MR0175/ISO 15156:2015 ©

ANSI/NACE/ISO 2015

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These materials are subject to copyright claims of ISO and NACE. No part of this publication may be reproduced in any form, including an electronic retrieval system, without the prior written permission of NACE. All requests pertaining to the ANSI/NACE MR0175/ISO 15156 standard should be submitted to NACE. All rights reserved.

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ANSI/NACE MR0175/ISO 15156

Contents

Page

Foreword......................................................................................................................................................................... iv Introduction ..................................................................................................................................................................... v 1

Scope ....................................................................................................................................................................1

Normative references ....................................................................................................................................2

Terms and definitions ....................................................................................................................................3

Abbreviated terms ..........................................................................................................................................6

General principles ...........................................................................................................................................6

Evaluation and definition of service conditions to enable material selection ..........................7

Selection of materials resistant to SSC/SCC in the presence of sulfides from existing lists and tables ..................................................................................................................................................7

8 8.1 8.2 8.3 8.3.1 8.3.2 8.3.3 8.3.4 8.3.5

Qualification of materials for H2S service ...............................................................................................8 Material description and documentation ...............................................................................................8 Qualification based upon field experience .............................................................................................8 Qualification based upon laboratory testing .........................................................................................8 General ................................................................................................................................................................8 Sampling of materials for laboratory testing ........................................................................................9 Selection of laboratory test methods........................................................................................................9 Conditions to be applied during testing ..................................................................................................9 Acceptance criteria .........................................................................................................................................9

Report of the method of selection or qualification..............................................................................9

Bibliography ................................................................................................................................................................. 11

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iii

ANSI/NACE MR0175/ISO 15156

Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries. This third edition cancels and replaces the second edition (ANSI/NACE MR0175/ISO 15156-1:2009), which has been technically revised to contain the following changes in the Scope and Clause 5: — replacement of the term “conventional elastic design criteria” by the term “load controlled design methods”;

ANSI/NACE MR0175/ISO 15156 consists of the following parts, under the general title Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas production: — Part 1: General principles for selection of cracking-resistant materials — Part 2: Cracking resistant carbon and low-alloy steels, and the use of cast irons — Part 3: Cracking resistant CRAs (corrosion resistant alloys) and other alloys

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— inclusion of improved guidance on the approach to the qualification of materials for use with strainbased design methods.

ANSI/NACE MR0175/ISO 15156

Introduction The consequences of sudden failures of metallic oil and gas field components, associated with their exposure to H2S-containing production fluids, led to the preparation of the first edition of ANSI/NACE MR0175, which was published in 1975 by the National Association of Corrosion Engineers, now known as NACE International. The original and subsequent editions of ANSI/NACE MR0175 established limits of H2S partial pressure above which precautions against sulfide stress cracking (SSC) were always considered necessary. They also provided guidance for the selection and specification of SSC-resistant materials when the H2S thresholds were exceeded. In more recent editions, NACE MR0175 has also provided application limits for some corrosion-resistant alloys, in terms of environmental composition and pH, temperature, and H2S partial pressures. In separate developments, the European Federation of Corrosion issued EFC Publication 16 in 1995 and EFC Publication 17 in 1996. These documents are generally complementary to those of NACE though they differed in scope and detail. In 2003, the publication of the three parts of ISO 15156 and ANSI/NACE MR0175/ISO 15156 was completed for the first time. These technically identical documents utilized the above sources to provide requirements and recommendations for materials qualification and selection for application in environments containing wet H2S in oil and gas production systems. They are complemented by NACE TM0177 and NACE TM0284 test methods. The revision of this part of ANSI/NACE MR0175/ISO 15156 involves a consolidation of all changes agreed and published in the Technical Circular 1, ANSI/NACE MR0175/ ISO 15156-1:2009/Cir.1:2014(E), published by the ISO 15156 Maintenance Agency secretariat at DIN. The changes were developed by, and approved by the ballot of, representative groups from within the oil and gas production industry. The great majority of these changes stem from issues raised by document users. A description of the process by which these changes were approved can be found at the ISO 15156 maintenance website www.iso.org/iso15156maintenance. When found necessary by oil and gas production industry experts, future interim changes to this part of ANSI/NACE MR0175/ISO 15156 will be processed in the same way and will lead to interim updates to this part of ANSI/NACE MR0175/ISO 15156 in the form of Technical Corrigenda or Technical Circulars. Document users should be aware that such documents can exist and can impact the validity of the dated references in this part of ANSI/NACE MR0175/ISO 15156. The ANSI/NACE MR0175/ISO 15156 Maintenance Agency at DIN was set up after approval by the ISO Technical Management Board given in document 34/2007. This document describes the makeup of the agency, which includes experts from NACE, EFC, and ISO/TC 67, and the process for approval of amendments. It is available from the ISO 15156 maintenance Web site and from the ISO/TC 67 Secretariat. The Web site also provides access to related documents that provide more detail on ANSI/NACE MR0175/ISO 15156 maintenance activities.

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ANSI/NACE MR0175/ISO 15156

Petroleum, petrochemical, and natural gas industries — Materials for use in H2S-containing environments in oil and gas production — Part 1: General principles for selection of cracking-resistant materials WARNING — Metallic materials selected using ANSI/NACE MR0175/ISO 15156 are resistant to cracking in defined H2S-containing environments in oil and gas production but not necessarily immune to cracking under all service conditions. It is the equipment user's responsibility to select materials suitable for the intended service.

1 Scope

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This part of ANSI/NACE MR0175/ISO 15156 describes general principles and gives requirements and recommendations for the selection and qualification of metallic materials for service in equipment used in oil and gas production and in natural-gas sweetening plants in H2S-containing environments, where the failure of such equipment can pose a risk to the health and safety of the public and personnel or to the environment. It can be applied to help to avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the materials requirements given in the appropriate design codes, standards, or regulations. This part of ANSI/NACE MR0175/ISO 15156 addresses all mechanisms of cracking that can be caused by H2S, including sulfide stress cracking, stress corrosion cracking, hydrogen-induced cracking and stepwise cracking, stress-oriented hydrogen-induced cracking, soft zone cracking, and galvanically induced hydrogen stress cracking. Table 1 provides a non-exhaustive list of equipment to which this part of ANSI/NACE MR0175/ISO 15156 is applicable, including permitted exclusions. This part of ANSI/NACE MR0175/ISO 15156 applies to the qualification and selection of materials for equipment designed and constructed using load controlled design methods. For design utilizing strainbased design methods, see Clause 5. This part of ANSI/NACE MR0175/ISO 15156 is not necessarily applicable to equipment used in refining or downstream processes and equipment.

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ANSI/NACE MR0175/ISO 15156

Table 1 — List of equipment ANSI/NACE MR0175/ISO 15156-1 is applicable to materials used for the following equipment Drilling, well construction, and well-servicing equipment

Permitted exclusions Equipment exposed only to drilling fluids of controlled compositiona Drill bits Blowout preventer (BOP) shear bladesb Drilling riser systems Work strings Wireline and wireline equipmentc Surface and intermediate casing

Wells, including subsurface equipment, gas-lift equipment, wellheads, and christmas trees

Sucker rod pumps and sucker rodsd Electric submersible pumps Other artificial lift equipment Slips

Flowlines, gathering lines, field facilities, and field processing plants

Crude-oil storage and handling facilities operating at a total absolute pressure below 0.45 MPa (65 psi)

Water-handling equipment

Water-handling facilities operating at a total absolute pressure below 0.45 MPa (65 psi)

Natural-gas treatment plants

—

Transportation pipelines for liquids, gases, and multiphase fluids

Lines handling gas prepared for general commercial and domestic use

For all equipment above

Components loaded only in compression

See ANSI/NACE MR0175/ISO 15156-2:2015, A.2.3.2.3 for more information.

See ANSI/NACE MR0175/ISO 15156-2:2015, A.2.3.2.1 for more information.

Wireline lubricators and lubricator connecting devices are not permitted exclusions.

For sucker rod pumps and sucker rods, reference can be made to NACE MR0176.

2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ANSI/NACE MR0175/ISO 15156-2:2015, Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas production — Part 2: Cracking-resistant carbon and low alloy steels, and the use of cast irons ANSI/NACE MR0175/ISO 15156-3:2015, Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas production — Part 3: Cracking-resistant CRAs (corrosionresistant alloys) and other alloys

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Water injection and water disposal equipment

ANSI/NACE MR0175/ISO 15156

3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 blowout preventer BOP mechanical device capable of containing pressure, used for control of well fluids and drilling fluids during drilling operations 3.2 braze, verb join metals by flowing a thin layer (of capillary thickness) of a lower-melting-point non-ferrous filler metal in the space between them 3.3 carbon steel alloy of carbon and iron containing up to 2 % mass fraction carbon and up to 1.65 % mass fraction manganese and residual quantities of other elements, except those intentionally added in specific quantities for deoxidation (usually silicon and/or aluminium) Note 1 to entry: Carbon steels used in the petroleum industry usually contain less than 0.8 % mass fraction carbon.

3.4 christmas tree equipment at a wellhead for the control of fluid production or injection 3.5 cold work, verb deform metal plastically under conditions of temperature and strain rate that induce strain hardening, usually, but not necessarily, conducted at room temperature 3.6 corrosion-resistant alloy CRA alloy intended to be resistant to general and localized corrosion of oilfield environments that are corrosive to carbon steels (3.3) 3.7 ferrite body-centred cubic crystalline phase of iron-based alloys 3.8 ferritic steel steel whose microstructure (3.15) at room temperature consists predominantly of ferrite (3.7) 3.9 hardness resistance of metal to plastic deformation, usually measured by indentation 3.10 heat-affected zone HAZ

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ANSI/NACE MR0175/ISO 15156

portion of the base metal that is not melted during brazing, cutting, or welding, but whose microstructure (3.15) and properties are altered by the heat of these processes 3.11 heat treatment heating and cooling a solid metal or alloy in such a way as to obtain desired properties Note 1 to entry: Heating for the sole purpose of hot working is not considered heat treatment.

3.12 hydrogen-induced cracking HIC planar cracking that occurs in carbon and low alloy steels when atomic hydrogen diffuses into the steel and then combines to form molecular hydrogen at trap sites Note 1 to entry: Cracking results from the pressurization of trap sites by hydrogen. No externally applied stress is required for the formation of hydrogen-induced cracks. Trap sites capable of causing HIC are commonly found in steels with high impurity levels that have a high density of planar inclusions and/or regions of anomalous microstructure (3.15)(e.g. banding) produced by segregation of impurity and alloying elements in the steel. This form of hydrogen-induced cracking is not related to welding.

3.13 hydrogen stress cracking HSC cracking that results from the presence of hydrogen in a metal and tensile stress (residual and/or applied) Note 1 to entry: HSC describes cracking in metals that are not sensitive to SSC but which can be embrittled by hydrogen when galvanically coupled, as the cathode, to another metal that is corroding actively as an anode. The term “galvanically induced HSC” has been used for this mechanism of cracking.

3.14 low-alloy steel steel with a total alloying element content of less than about 5 % mass fraction, but more than specified for carbon steel (3.3)

3.16 partial pressure pressure that would be exerted by a single component of a gas if present alone, at the same temperature, in the total volume occupied by the mixture Note 1 to entry: For a mixture of ideal gases, the partial pressure of each component is equal to the total pressure multiplied by its mole fraction in the mixture, where its mole fraction is equal to the volume fraction of the component.

3.17 residual stress stress present in a component free of external forces or thermal gradients

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3.15 microstructure structure of a metal as revealed by microscopic examination of a suitably prepared specimen

ANSI/NACE MR0175/ISO 15156

3.18 soft-zone cracking SZC form of SSC that can occur when a steel contains a local “soft zone” of low-yield-strength material Note 1 to entry: Under service loads, soft zones can yield and accumulate plastic strain locally, increasing the SSC susceptibility to cracking of an otherwise SSC-resistant material. Such soft zones are typically associated with welds in carbon steels (3.3).

3.19 sour service exposure to oilfield environments that contain sufficient H2S to cause cracking of materials by the mechanisms addressed by this part of ANSI/NACE MR0175/ISO 15156 3.20 stepwise cracking SWC cracking that connects hydrogen-induced cracks on adjacent planes in a steel Note 1 to entry: This term describes the crack appearance. The linking of hydrogen-induced cracks to produce stepwise cracking is dependent on the local strain between the cracks and the embrittlement of the surrounding steel by dissolved hydrogen. HIC/SWC is usually associated with low-strength plate steels used in the production of pipes and vessels.

3.21 stress corrosion cracking SCC cracking of metal involving anodic processes of localized corrosion and tensile stress (residual and/or applied) in the presence of water and H2S Note 1 to entry: Chlorides and/or oxidants and elevated temperature can increase the susceptibility of metals to this mechanism of attack.

3.22 stress-oriented hydrogen-induced cracking SOHIC staggered small cracks formed approximately perpendicular to the principal stress (residual or applied) resulting in a “ladder-like” crack array linking (sometimes small) pre-existing HIC cracks Note 1 to entry: The mode of cracking can be categorized as SSC caused by a combination of external stress and the local strain around hydrogen-induced cracks. SOHIC is related to SSC and HIC/SWC. It has been observed in parent material of longitudinally welded pipe and in the heat-affected zone (HAZ) (3.10) of welds in pressure vessels. SOHIC is a relatively uncommon phenomenon usually associated with low-strength ferritic pipe and pressure vessel steels.

3.23 sulfide stress cracking SSC cracking of metal involving corrosion and tensile stress (residual and/or applied) in the presence of water and H2S Note 1 to entry: SSC is a form of hydrogen stress cracking (HSC) (3.13) and involves the embrittlement of the metal by atomic hydrogen that is produced by acid corrosion on the metal surface. Hydrogen uptake is promoted in the presence of sulfides. The atomic hydrogen can diffuse into the metal, reduce ductility, and increase susceptibility to cracking. High-strength metallic materials and hard weld zones are prone to SSC.

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ANSI/NACE MR0175/ISO 15156

3.24 weld, verb join two or more pieces of metal by applying heat and/or pressure with or without filler metal, to produce a union through localized fusion of the substrates and solidification across the interfaces 3.25 yield strength stress at which a material exhibits a specified deviation from the proportionality of stress to strain Note 1 to entry: The deviation is expressed in terms of strain by either the offset method (usually at a strain of 0.2 %) or the total-extension-under-load method (usually at a strain of 0.5 %).

4 Abbreviated terms BOP

blowout preventer

CRA

corrosion-resistant alloy

HAZ

heat-affected zone

HIC

hydrogen-induced cracking

HSC

hydrogen stress cracking

SCC

stress-corrosion cracking

SOHIC

stress-oriented hydrogen-induced cracking

SWC

step-wise cracking

SSC

sulfide stress cracking

SZC

soft-zone cracking

5 General principles Users of the ANSI/NACE MR0175/ISO 15156 series shall first assess the conditions to which the materials they wish to select can be exposed. These conditions shall be evaluated, defined, and documented in accordance with this part of ANSI/NACE MR0175/ISO 15156. The equipment user shall determine whether or not the service conditions are such that the ANSI/NACE MR0175/ISO 15156 series applies. --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Materials selection shall be made following the requirements and recommendations of ANSI/NACE MR0175/ISO 15156-2 or ANSI/NACE MR0175/ISO 15156-3, as appropriate. The use of ANSI/NACE MR0175/ISO 15156-2 or ANSI/NACE MR0175/ISO 15156-3 can require an exchange of information (for example, concerning required or suitable service conditions) between the equipment user and the equipment or materials supplier. If necessary, the equipment user should advise other parties of the service conditions. NOTE It can be necessary for the equipment supplier to exchange information with the equipment manufacturer, the materials supplier, and/or the materials manufacturer.

Qualification, with respect to a particular mode of failure, for use in defined service conditions also qualifies a material for use under other service conditions that are equal to or less severe in all respects than the conditions for which qualification was carried out. It is the equipment user's responsibility to ensure that any material specified for use in their equipment is satisfactory in the service environment.

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ANSI/NACE MR0175/ISO 15156

It is the equipment or materials supplier's responsibility to comply with the requirements for the marking/documentation of materials in accordance with ANSI/NACE MR0175/ISO 15156-2:2015, Clause 9 or ANSI/NACE MR0175/ISO 15156-3:2015, 7.2, as appropriate. This part of ANSI/NACE MR0175/ISO 15156 applies to the qualification and selection of materials for equipment designed and constructed using load controlled design methods. For designs utilizing strainbased design methods, use of this part of ANSI/NACE MR0175/ISO 15156 might not be appropriate and other test methods, not addressed in ANSI/NACE MR0175/ISO 15156, might be required. The equipment/material supplier, in conjunction with the equipment user, shall define and agree on other testing requirements and acceptance criteria.

6 Evaluation and definition of service conditions to enable material selection 6.1 Before selecting or qualifying materials using ANSI/NACE MR0175/ISO 15156-2 or ANSI/NACE MR0175/ISO 15156-3, the user of the equipment shall define, evaluate, and document the service conditions to which materials can be exposed for each application. The defined conditions shall include both intended exposures and unintended exposures that can result from the failure of primary containment or protection methods. Particular attention shall be paid to the quantification of those factors known to affect the susceptibility of materials to cracking caused by H2S. Factors, other than material properties, known to affect the susceptibility of metallic materials to cracking in H2S service include H2S partial pressure, in situ pH, the concentration of dissolved chloride or other halide, the presence of elemental sulfur or other oxidant, temperature, galvanic effects, mechanical stress, and time of exposure to contact with a liquid water phase. 6.2

The documented service conditions shall be used for one or more of the following purposes:

a) to provide the basis for selection of SSC/SCC-resistant materials from existing lists and tables (see Clause 7); b) to provide the basis for qualification and selection based upon documented field experience (see 8.2); c) to define the laboratory test requirements to qualify a material for H2S service with respect to one or more of SSC, SCC, HIC, SOHIC, SZC, and/or galvanically induced HSC (see 8.3); d) to provide the basis for the reassessment of the suitability of existing alloys of construction, using Clause 7, 8.2, and/or 8.3, in the event of changes to the actual or intended service conditions.

7 Selection of materials resistant to SSC/SCC in the presence of sulfides from existing lists and tables SSC-resistant carbon and low-alloy steels may be selected from the materials identified in ANSI/NACE MR0175/ISO 15156-2:2015, Annex A. SSC, SCC-resistant CRAs and other alloys may be selected from the materials identified in ANSI/NACE MR0175/ISO 15156-3:2015, Annex A. Generally, no additional laboratory testing of materials selected in these ways is required. The materials listed have given acceptable performance under the stated metallurgical, environmental, and mechanical conditions based on field experience and/or laboratory testing. The equipment user should, 7

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It is the equipment or materials supplier's responsibility to meet the metallurgical and manufacturing requirements and, when necessary, any additional testing requirements of the ANSI/NACE MR0175/ISO 15156 series for the material selected in the condition in which it enters into service.

ANSI/NACE MR0175/ISO 15156

nevertheless, give consideration to specific testing of materials for applications where they consider the potential consequences of failure make this justifiable (see WARNING).

8 Qualification of materials for H2S service 8.1 Material description and documentation The material being qualified shall be described and documented, such that those of its properties likely to affect performance in H2S-containing media are defined. The tolerances or ranges of properties that can occur within the material shall be described and documented. Metallurgical properties known to affect performance in H2S-containing environments include chemical composition, method of manufacture, product form, strength, hardness, amount of cold work, heattreatment condition, and microstructure.

8.2 Qualification based upon field experience A material may be qualified by documented field experience. The material description shall meet the requirements of 8.1. The description of the service conditions in which the experience has been gained shall meet the relevant requirements of 6.1. The duration of the documented field experience shall be at least two years and should preferably involve a full examination of the equipment following field use. The severity of intended service conditions shall not exceed that of the field experience for which documented records are available.

8.3 Qualification based upon laboratory testing 8.3.1 General Laboratory testing can only approximate field service. Laboratory testing in accordance with the ANSI/NACE MR0175/ISO 15156 series may be used for the following: — to qualify metallic materials for their resistance to SSC and/or SCC under service conditions up to the limits that apply to materials of similar types listed in ANSI/NACE MR0175/ISO 15156-2 and ANSI/NACE MR0175/ISO 15156-3; — to qualify metallic materials for their resistance to SSC and/or SCC under service conditions with other limits;

— to qualify carbon and low-alloy steels with respect to their resistance to HIC, SOHIC, or SZC; — to qualify corrosion-resistant or other alloys with respect to their resistance to galvanically induced HSC; — to provide qualification data for a material not currently listed in ANSI/NACE MR0175/ISO 15156-2:2015, Annex A and ANSI/NACE MR0175/ISO 15156-3:2015, Annex A in such a form that it may be considered for inclusion at a later date.

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EXAMPLE Qualification up to a higher-than-normally-acceptable level of H2S, to a lower-than-normallyrequired test stress or to revised temperature limit(s) or to a lower pH.

ANSI/NACE MR0175/ISO 15156

8.3.2 Sampling of materials for laboratory testing The method of sampling the material for laboratory testing shall be reviewed and accepted by the equipment user. The test samples shall be representative of the commercial product. For multiple batches of a material produced to a single specification, an assessment shall be made of the properties that influence cracking behaviour in H2S-containing environments (see 8.1). The distributions of these properties shall be considered when selecting samples for testing according to the requirements of ANSI/NACE MR0175/ISO 15156-2 and ANSI/NACE MR0175/ISO 15156-3. The materials in the metallurgical condition that has the greatest susceptibility to cracking in H2S service shall be used for the selection of the test samples. Materials source, method of preparation, and surface condition of samples for testing shall be documented. 8.3.3 Selection of laboratory test methods For carbon and low-alloy steels, test methods for SSC, HIC, SOHIC and/or SZC shall be selected from ANSI/NACE MR0175/ISO 15156-2 as required. For CRAs and other alloys, test methods for SSC, SCC, and galvanically induced HSC shall be selected from ANSI/NACE MR0175/ISO 15156-3 as required. 8.3.4 Conditions to be applied during testing For qualification of carbon and low-alloy steels for general sour service applications or for more restricted application ranges, standardized test environments and mechanical test conditions shall be chosen from those described in ANSI/NACE MR0175/ISO 15156-2. For qualification of CRAs or other alloys for the restricted application ranges appropriate to each alloy type, the standardized test environments and mechanical test conditions shall be chosen from those described in ANSI/NACE MR0175/ISO 15156-3. For qualification of a material for use in application-specific service conditions, the equipment user shall take care to ensure that the test conditions and the test results obtained from them are appropriate for those specific service conditions. All the test conditions applied shall be at least as severe, with respect to the potential mode of failure, as those defined to occur in the field service (see 6.1). The pH applied shall represent the service in situ pH. The justification of the selection of the test environment and mechanical test conditions with respect to a specific application shall be documented by the equipment user. 8.3.5 Acceptance criteria Test acceptance criteria shall be as defined for each test method in ANSI/NACE MR0175/ISO 15156-2 and ANSI/NACE MR0175/ISO 15156-3.

9 Report of the method of selection or qualification Materials selected or qualified in accordance with this part of ANSI/NACE MR0175/ISO 15156 shall have the method of selection documented by reporting item a) from the following list, together with one other item [b), c), or d)]: a) for all materials, evaluation of the service conditions (see 6.1);

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ANSI/NACE MR0175/ISO 15156

c) for a material selected on the basis of field experience, documentation describing the following: 1) mechanism(s) of cracking for which qualification and selection has been made; 2) material used (see 8.1); 3) field experience (see 8.2); d) for a material selected on the basis of qualification by laboratory testing, a test report describing the following: 1) mechanism(s) of cracking for which qualification and selection has been made; 2) material selected for laboratory testing (see 8.1); 3) selection, sampling, and preparation of test specimens (see 8.3.2); 4) justification of the test environment and physical test conditions for qualification (see 8.3.3); 5) test results that demonstrate compliance with ANSI/NACE MR0175/ISO 15156-2 or ANSI/NACE MR0175/ISO 15156-3 (see 8.3). The equipment user shall be responsible for ensuring that the required documentation is prepared.

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b) for a material selected with respect to SSC and/or SCC resistance, from lists and tables (see Clause 7), documentation making reference to the relevant subclauses of ANSI/NACE MR0175/ISO 15156-2 or ANSI/NACE MR0175/ISO 15156-3;

ANSI/NACE MR0175/ISO 15156

Bibliography

[1]

ANSI NACE1 MR0175:2003, Metals for Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments

[2]

ANSI NACE TM0177, Laboratory testing of metals for resistance to sulfide stress cracking and stress corrosion cracking in H2S environments

[3]

ANSI NACE TM0284, Evaluation of pipeline and pressure vessel steels for resistance to hydrogen induced cracking

[4]

NACE MR0176, Metallic materials for sucker-rod pumps for corrosive oilfield environments

[5]

EFC2 Publication 16, Guidelines on materials requirements for carbon and low alloy steels for H2Scontaining environments in oil and gas production

[6]

EFC Publication 17, Corrosion resistant alloys for oil and gas production: guidelines on general requirements and test methods for H2S service

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NACE International, 15835 Park Ten Place, Houston, TX 77084-5145, USA.

European Federation of Corrosion, c/o The Institute of Materials, 1 Carlton House Terrace, London SW1Y 5DB, UK.

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Item No. 21307

International Standard ANSI/NACE MR0175/ISO 15156-2:2015

Petroleum, petrochemical and natural gas industries — Materials for use in H2S-containing environments in oil and gas production — Part 2:

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Cracking-resistant carbon and lowalloy steels, and the use of cast irons An American National Standard Approved November 23, 2015

Reference number ANSI/NACE MR0175/ISO 15156:2015

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ANSI/NACE/ISO 2015

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NACE International 15835 Park Ten Place Houston, TX 77084-5145 Tel. +1 281-228-6223 Fax +1 281-228-6300 Web: www.nace.org

Printed in the U.S.A. by NACE International

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Contents

Page

Foreword .......................................................................................................................................................................... v 1

Scope .................................................................................................................................................................... 1

Normative references .................................................................................................................................... 2

Terms and definitions ................................................................................................................................... 3

Symbols and abbreviated terms ................................................................................................................ 6

Purchasing information ................................................................................................................................ 7

Factors affecting the behaviour of carbon and low alloy steels in H2S-containing environments ................................................................................................................................................... 7

Qualification and selection of carbon and low-alloy steels with resistance to SSC, SOHIC and SZC ................................................................................................................................................................ 8 Option 1 — Selection of SSC-resistant steels (and cast irons) using A.2 ..................................... 8 For pH2S < 0.3 kPa (0.05 psi) ..................................................................................................................... 8 For pH2S ≥ 0.3 kPa (0.05 psi) ..................................................................................................................... 8

7.1 7.1.1 7.1.2 7.2 7.2.1 7.2.2 7.3 7.3.1 7.3.2 7.3.3 7.4

Option 2 — Selection of steels for specific sour-service applications or for ranges of sour service ....................................................................................................................................................... 8 Sulfide stress cracking................................................................................................................................... 8 SOHIC and SZC................................................................................................................................................ 10 Hardness requirements ............................................................................................................................. 10 General ............................................................................................................................................................. 10 Parent metals................................................................................................................................................. 10 Welds ................................................................................................................................................................ 11 Other fabrication methods ....................................................................................................................... 15

Evaluation of carbon and low alloy steels for their resistance to HIC/SWC ........................... 15

Marking, labelling, and documentation ............................................................................................... 16

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Introduction ..................................................................................................................................................................vii

Annex A (normative) SSC-resistant carbon and low alloy steels (and requirements and recommendations for the use of cast irons) ....................................................................................... 17 A.1

General ............................................................................................................................................................. 17

A.2

SSC-resistant carbon and low-alloy steels and the use of cast irons ......................................... 17

A.2.1 General requirements for carbon and low alloy steels .................................................................. 17 A.2.1.1 General ............................................................................................................................................................. 17 A.2.1.2 Parent metal composition, heat treatment and hardness............................................................. 17 A.2.1.3 Carbon steels acceptable with revised or additional restrictions .............................................. 18 A.2.1.4 Welding ............................................................................................................................................................ 18 A.2.1.5 Surface treatments, overlays, plating, coatings, linings, etc. ........................................................ 19 A.2.1.6 Cold deformation and thermal stress relief ....................................................................................... 19 A.2.1.7 Threading ........................................................................................................................................................ 20 A.2.1.8 Cold deformation of surfaces ................................................................................................................... 20 © NACE/ISO 2015

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

A.2.1.9 Identification stamping .............................................................................................................................. 20 A.2.2 Application to product forms ................................................................................................................... 20 A.2.2.1 General ............................................................................................................................................................. 20 A.2.2.2 Pipe, plate, and fittings ............................................................................................................................... 20 A.2.2.3 Downhole casing, tubing, and tubular components ........................................................................ 21 A.2.2.4 Bolting and fasteners .................................................................................................................................. 22 A.2.3 Application to equipment.......................................................................................................................... 22 A.2.3.1 General ............................................................................................................................................................. 22 A.2.3.2 Drilling blowout preventers..................................................................................................................... 22 A.2.3.2.1 Shear blades ............................................................................................................................................... 22 A.2.3.2.2 Shear rams .................................................................................................................................................. 22 A.2.3.2.3 Drilling, well construction and well-servicing equipment exposed only to drilling fluids of controlled composition ............................................................................................. 23 A.2.3.3 Compressors and pumps ........................................................................................................................... 23 A.2.3.3.1 Compressor impellers ............................................................................................................................ 23 A.2.3.3.2 Special provisions for compressors and pumps ........................................................................... 23 A.2.4 Requirements for the use of cast irons................................................................................................. 23 A.2.4.1 General ............................................................................................................................................................. 23 A.2.4.2 Packers and subsurface equipment ...................................................................................................... 23 A.2.4.3 Compressors and pumps ........................................................................................................................... 24 A.3

SSC-resistant steels for use throughout SSC region 2...................................................................... 24

A.3.1 General ............................................................................................................................................................. 24 A.3.2 Downhole casing, tubing, and tubular components ........................................................................ 24 A.3.3 Pipeline steels ............................................................................................................................................... 24 A.4

SSC-resistant steels for use throughout SSC region 1...................................................................... 24

A.4.1 General ............................................................................................................................................................. 24 A.4.2 Downhole casing, tubing, and tubular components ........................................................................ 24 A.4.3 Pipeline steels ............................................................................................................................................... 24 Annex B (normative) Qualification of carbon and low-alloy steels for H2S service by laboratory testing ............................................................................................................................................................... 25 B.1

Requirements ................................................................................................................................................ 25

B.2

Uses of laboratory qualifications............................................................................................................ 25

B.2.1 General ............................................................................................................................................................. 25 B.2.2 Qualification of manufactured products.............................................................................................. 26 B.2.3 Qualification of a manufacturing source and route ......................................................................... 27 B.2.4 Use of laboratory testing as a basis for proposing additions and changes to Annex A ....... 27 B.3

Test procedures to evaluate the resistance of carbon and low-alloy steels to SSC .............. 28

B.4

Test procedures to evaluate the resistance of carbon and low-alloy steels to SOHIC and SZC ..................................................................................................................................................................... 30 --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

B.4.1 General ............................................................................................................................................................. 30 B.4.2 Small-scale tests............................................................................................................................................ 30 B.4.2.1 Specimen selection ...................................................................................................................................... 30 B.4.2.2 Evaluation and acceptance criteria for UT test specimens ........................................................... 30 B.4.2.3 Evaluation and acceptance criteria for FPB test specimens ......................................................... 31 B.4.3 Full pipe ring tests ....................................................................................................................................... 31 B.5

Test procedures and acceptance criteria to evaluate the resistance of carbon and lowalloy steels to HIC/SWC .............................................................................................................................. 31

Annex C (informative) Determination of H2S partial pressure ................................................................... 33 C.1

Calculation of partial pressure of H2S for systems with a gas phase ......................................... 33

C.2

Calculations of effective H2S partial pressure for gas-free liquid systems .............................. 33

Annex D (informative) Recommendations for determining pH .................................................................. 35 Annex E (informative) Information that should be supplied for material purchasing ...................... 40

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Bibliography ................................................................................................................................................................. 42

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries. This third edition cancels and replaces the second edition (ANSI/NACE MR0175/ISO 15156-2:2009), of which it constitutes a minor revision, specifically by the following: — replacement in the Scope of the term “conventional elastic design criteria” by the term “load controlled design methods”; — inclusion in both 7.2.1.1 and A.2.1.1 of information that emphasizes the possibilities for the qualification for a specific sour service or range of sour service of carbon and low alloy steels not listed in Annex A; — replacement of paragraph 6 of A.2.1.4 to improve the guidance on the welding of carbon and low alloy steels not covered elsewhere in this subclause. ANSI/NACE MR0175/ISO 15156 consists of the following parts, under the general title Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas production — Part 1: General principles for selection of cracking-resistant materials — Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons — Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Introduction The consequences of sudden failures of metallic oil and gas field components, associated with their exposure to H2S-containing production fluids, led to the preparation of the first edition of NACE MR0175, which was published in 1975 by the National Association of Corrosion Engineers, now known as NACE International. The original and subsequent editions of NACE MR0175 established limits of H2S partial pressure above which precautions against sulfide stress cracking (SSC) were always considered necessary. They also provided guidance for the selection and specification of SSC-resistant materials when the H2S thresholds were exceeded. In more recent editions, NACE MR0175 has also provided application limits for some corrosion-resistant alloys, in terms of environmental composition and pH, temperature, and H2S partial pressures. In separate developments, the European Federation of Corrosion issued EFC Publication 16 in 1995 and EFC Publication 17 in 1996. These documents are generally complementary to those of NACE though they differed in scope and detail. In 2003, the publication of the ISO 15156 series and ANSI/NACE MR0175/ISO 15156 was completed for the first time. These technically identical documents utilized the above sources to provide requirements and recommendations for materials qualification and selection for application in environments containing wet H2S in oil and gas production systems. They are complemented by NACE TM0177 and NACE TM0284 test methods. The revision of this part of ANSI/NACE MR0175/ISO 15156 involves a consolidation of all changes agreed and published in the Technical Circular 1, ANSI/NACE MR0175/ISO 15156-2:2009/Cir.1:2011(E) and the Technical Circular 2, ANSI/NACE MR0175/ISO 15156-2:2009/Cir.2:2014(E), published by the ISO 15156 Maintenance Agency secretariat at DIN. The changes were developed by and approved by the ballot of, representative groups from within the oil and gas production industry. The great majority of these changes stem from issues raised by document users. A description of the process by which these changes were approved can be found at the ISO 15156 maintenance Web site: www.iso.org/iso15156maintenance. When found necessary by oil and gas production industry experts, future interim changes to this part of ANSI/NACE MR0175/ISO 15156 will be processed in the same way and will lead to interim updates to this part of ANSI/NACE MR0175/ISO 15156 in the form of Technical Corrigenda or Technical Circulars. Document users should be aware that such documents can exist and can impact the validity of the dated references in this part of ANSI/NACE MR0175/ISO 15156. The ISO 15156 Maintenance Agency at DIN was set up after approval by the ISO Technical Management Board given in document 34/2007. This document describes the makeup of the agency, which includes experts from NACE, EFC, and ISO/TC 67, and the process for approval of amendments. It is available from the ISO 15156 maintenance Web site and from the ISO/TC 67 Secretariat. The website also provides access to related documents that provide more detail on ANSI/NACE MR0175/ISO 15156 maintenance activities.

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vii

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Petroleum, petrochemical and natural gas industries — Materials for use in H2S-containing environments in oil and gas production — Part 2: Cracking-resistant carbon and lowalloy steels, and the use of cast irons WARNING — Carbon and low-alloy steels and cast irons selected using this part of ANSI/NACE MR0175/ISO 15156 are resistant to cracking in defined H2S-containing environments in oil and gas production but not necessarily immune to cracking under all service conditions. It is the equipment user's responsibility to select the carbon and low-alloy steels and cast irons suitable for the intended service.

1 Scope This part of ANSI/NACE MR0175/ISO 15156 gives requirements and recommendations for the selection and qualification of carbon and low-alloy steels for service in equipment used in oil and natural gas production and natural gas treatment plants in H2S-containing environments, whose failure can pose a risk to the health and safety of the public and personnel or to the environment. It can be applied to help to avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the materials requirements of the appropriate design codes, standards or regulations. This part of ANSI/NACE MR0175/ISO 15156 addresses the resistance of these steels to damage that can be caused by sulfide stress cracking (SSC) and the related phenomena of stress-oriented hydrogen-induced cracking (SOHIC) and soft-zone cracking (SZC). This part of ANSI/NACE MR0175/ISO 15156 also addresses the resistance of these steels to hydrogeninduced cracking (HIC) and its possible development into stepwise cracking (SWC). This part of ANSI/NACE MR0175/ISO 15156 is concerned only with cracking. Loss of material by general (mass loss) or localized corrosion is not addressed. Table 1 provides a non-exhaustive list of equipment to which this part of ANSI/NACE MR0175/ISO 15156 is applicable, including permitted exclusions. This part of ANSI/NACE MR0175/ISO 15156 applies to the qualification and selection of materials for equipment designed and constructed using load controlled design methods. For design utilizing strainbased design methods, see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 5. Annex A lists SSC-resistant carbon and low alloy steels, and A.2.4 includes requirements for the use of cast irons. This part of ANSI/NACE MR0175/ISO 15156 is not necessarily suitable for application to equipment used in refining or downstream processes and equipment.

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Table 1 — List of equipment ANSI/NACE MR0175/ISO 15156 is applicable to materials used for the following equipment Drilling, well construction and well-servicing equipment

Wells, including subsurface equipment, gas lift equipment, wellheads and christmas trees

Sucker rod pumps and sucker rodsd Electric submersible pumps Other artificial lift equipment Slips

Flow-lines, gathering lines, field facilities and field processing plants

Crude oil storage and handling facilities operating at a total absolute pressure below 0.45 MPa (65 psi)

Water-handling equipment

Water-handling facilities operating at a total absolute pressure below 0.45 MPa (65 psi) Water injection and water disposal equipment

Natural gas treatment plants

—

Transportation pipelines for liquids, gases and multiphase fluids

Lines handling gas prepared for general commercial and domestic use

For all equipment above

Components loaded only in compression

See A.2.3.2.3 for more information.

See A.2.3.2.1 for more information.

Wireline lubricators and lubricator connecting devices are not permitted exclusions.

For sucker rod pumps and sucker rods, reference can be made to NACE MR0176.

2 Normative references

ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature ISO 10423, Petroleum and natural gas industries — Drilling and production equipment — Wellhead and Christmas tree equipment 2 Copyright NACE International Provided by IHS under license with NACE No reproduction or networking permitted without license from IHS

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The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ANSI/NACE MR0175/ISO 15156-2:2015(E) ANSI/NACE MR0175/ISO 15156-1:2015, Petroleum and natural gas industries — Materials for use in H2Scontaining environments in oil and gas production — Part 1: General principles for selection of crackingresistant materials ANSI/NACE MR0175/ISO 15156-3:2015, Petroleum and natural gas industries — Materials for use in H2Scontaining environments in oil and gas production — Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys NACE TM0177,1 Laboratory testing of metals for resistance to sulfide stress cracking and stress corrosion cracking in H2S environments NACE TM0284, Evaluation of pipeline and pressure vessel steels for resistance to hydrogen-induced cracking EFC Publications Number 16, Guidelines on materials requirements for carbon and low alloy steels for H2Scontaining environments in oil and gas production2 SAE AMS-2430,3 Shot Peening, Automatic

3 Terms and definitions For the purposes of this document, the terms and definitions given in ANSI/NACE MR0175/ISO 15156-1 and the following apply. 3.1 Brinell hardness HBW hardness value, measured in accordance with ISO 6506-1, normally using a 10 mm diameter tungsten ball and a force of 29.42 kN Note 1 to entry: For the purposes of this provision, ASTM E10 is equivalent to ISO 6506-1.

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3.2 bubble-point pressure pB pressure under which gas bubbles form in a liquid at a particular operating temperature Note 1 to entry: See C.2.

3.3 burnish process of smoothing surfaces using frictional contact between the material and some other hard pieces of material, such as hardened steel balls 3.4 casting metal that is obtained at or near its finished shape by the solidification of molten metal in a mould

1 NACE International, 15835 Park Ten Place, Houston, Texas 77084-5145, USA. 2 European Federation of Corrosion, available from The Institute of Materials, 1 Carlton House Terrace, London SW1Y 5DB, UK

[ISBN 0-901716-95-2]. 3 Society of Automotive Engineers (SAE), 400 Commonwealth Drive, Warrendale, PA 15096-0001 USA. © NACE/ISO 2015 Copyright NACE International Provided by IHS under license with NACE No reproduction or networking permitted without license from IHS

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ANSI/NACE MR0175/ISO 15156-2:2015(E) 3.5 cast iron iron-carbon alloy containing approximately 2 % to 4 % mass fraction carbon 3.5.1 grey cast iron cast iron that displays a grey fracture surface due to the presence of flake graphite 3.5.2 white cast iron cast iron that displays a white fracture surface due to the presence of cementite 3.5.3 malleable iron white cast iron that is thermally treated to convert most or all of the cementite to graphite (temper carbon) 3.5.4 ductile iron nodular cast iron cast iron that has been treated while molten with an element (usually magnesium or cerium) that spheroidizes the graphite 3.6 cementite microstructural constituent of steels composed principally of iron carbide (Fe3C) 3.7 cold working cold deforming cold forging cold forming deforming metal plastically under conditions of temperature and strain rate that induce strain-hardening, usually, but not necessarily, conducted at room temperature

3.9 free-machining steel steel to which elements such as sulfur, selenium, and lead have been added intentionally to improve machineability 3.10 lower critical temperature temperature of a ferrous metal at which austenite begins to form during heating or at which the transformation of austenite is completed during cooling 3.11 nitriding case-hardening process in which nitrogen is introduced into the surface of metallic materials (most commonly ferrous alloys) EXAMPLES

Liquid nitriding, gas nitriding, ion nitriding and plasma nitriding.

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3.8 fitness-for-purpose suitability for use under the expected service conditions

ANSI/NACE MR0175/ISO 15156-2:2015(E) 3.12 normalizing heating a ferrous metal to a suitable temperature above the transformation range (austenitizing), holding at temperature for a suitable time and then cooling in still air (or protective atmosphere) to a temperature substantially below the transformation range 3.13 plastically deformed permanently deformed by stressing beyond the limit of elasticity, i.e. the limit of proportionality of stress to strain 3.14 pressure-containing part part whose failure to function as intended results in a release of retained fluid to the atmosphere EXAMPLES

Valve bodies, bonnets and stems.

3.15 quenched and tempered quench hardened and then tempered 3.16 Rockwell C hardness HRC hardness value, measured in accordance with ISO 6508, obtained using a diamond cone indenter and a force of 1 471 N Note 1 to entry: For the purposes of this provision, ASTM E18 is equivalent to ISO 6508-1.

3.17 shot-peening inducing compressive stresses in the surface layer of a material by bombarding it with a selected medium (usually round steel shot) under controlled conditions

3.19 tempering heat treatment by heating to a temperature below the lower critical temperature, for the purpose of decreasing the hardness and increasing the toughness of hardened steel, hardened cast iron and, sometimes, normalized steel 3.20 tensile strength ultimate strength ratio of maximum load to original cross-sectional area Note 1 to entry: See ISO 6892-1.

3.21 test batch group of items representing a production batch whose conformity with a specified requirement can be determined by testing representative samples in accordance with a defined procedure ÂŠ NACE/ISO 2015 Copyright NACE International Provided by IHS under license with NACE No reproduction or networking permitted without license from IHS

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3.18 stress relief heating a metal to a suitable temperature, holding at that temperature long enough to reduce residual stresses, and then cooling slowly enough to minimize the development of new residual stresses

ANSI/NACE MR0175/ISO 15156-2:2015(E) 3.22 tubular component cylindrical component (pipe) having a longitudinal hole, used in drilling/production operations for conveying fluids 3.23 Vickers hardness HV hardness value, measured in accordance with ISO 6507-1, obtained using a diamond pyramid indenter and one of a variety of possible applied loads Note 1 to entry: For the purposes of this provision, ASTM E384 is equivalent to ISO 6507-1.

3.24 weldment portion of a component on which welding has been performed, including the weld metal, the heat-affected zone (HAZ), and the adjacent parent metal 3.25 weld metal portion of a weldment that has been molten during welding 3.26 wrought (metal in the solid condition) formed to a desired shape by working (rolling, extruding, forging, etc.), usually at an elevated temperature

4 Symbols and abbreviated terms For the purposes of this document, the abbreviated terms given in ANSI/NACE MR0175/ISO 15156-1 and the following apply. AYS

actual yield strength

CLR

crack length ratio

CSR

crack surface ratio

CTR

crack thickness ratio

DCB

double cantilever beam (test)

FPB

four-point bend (test)

HBW

Brinell hardness

HIC

hydrogen-induced cracking --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

HRC

Rockwell hardness (scale C)

HSC

hydrogen stress cracking

Vickers hardness

OCTG

oil country tubular goods, i.e. casing, tubing and drill pipe

pH 2S

partial pressure of H2S

Rp0.2

0.2 % proof stress in accordance with ISO 6892-1

SMYS

specified minimum yield strength

SOHIC

stress-oriented hydrogen-induced cracking

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ANSI/NACE MR0175/ISO 15156-2:2015(E) SSC

sulfide stress-cracking

SWC

stepwise cracking

SZC

soft-zone cracking

temperature

UNS

Unified Numbering System (from SAE-ASTM, Metals and alloys in the Unified Numbering System)

uniaxial tensile (test)

5 Purchasing information 5.1 The preparation of material purchasing specifications can require co-operation and exchange of data between the equipment user, the equipment supplier and the material manufacturer to ensure that the material purchased complies with ANSI/NACE MR0175/ISO 15156-1 and this part of ANSI/NACE MR0175/ISO 15156. 5.2

The following information shall be provided:

— preferred material types and/or grades (if known); — equipment type (if known); — reference to this part of ANSI/NACE MR0175/ISO 15156; — acceptable bases for selection of materials for SSC resistance (see Clause 7); --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

— requirements for HIC resistance (see Clause 8). 5.3 The equipment user and the equipment supplier/material manufacturer may agree that carbon or low-alloy steels other than those described and/or listed in Annex A may be selected subject to suitable qualification testing in accordance with Annex B and ANSI/NACE MR0175/ISO 15156-1. The qualification requirements may be extended to include resistance to SOHIC and SZC. If the purchaser intends to make use of such agreements, extensions and qualifications, the appropriate additional information shall be clearly indicated in the materials purchasing specification. This information may include — requirements for SSC testing (see 7.1 and 7.2), — service conditions for specific sour-service application, and — other special requirements. 5.4 Annex C describes how to calculate the H2S partial pressure and Annex D gives guidance on how to determine the pH-value of a fluid. 5.5 The information required for material purchasing shall be entered on suitable data sheets. Suggested formats are given in Annex E.

6 Factors affecting the behaviour of carbon and low alloy steels in H2S-containing environments The behaviour of carbon and low-alloy steels in H2S-containing environments is affected by complex interactions of parameters, including the following:

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ANSI/NACE MR0175/ISO 15156-2:2015(E) a) chemical composition, method of manufacture, product form, strength, hardness of the material and its local variations, amount of cold work, heat-treatment condition, microstructure, microstructural uniformity, grain size and cleanliness of the material; b) H2S partial pressure or equivalent concentration in the water phase; c) chloride ion concentration in the water phase; d) acidity (pH) of the water phase; e) presence of sulfur or other oxidants; f)

exposure to non-production fluids;

g) exposure temperature; h) total tensile stress (applied plus residual); i)

exposure time.

These factors shall be considered when using this part of ANSI/NACE MR0175/ISO 15156 for the selection of materials suitable for environments containing H2S in oil and gas production systems.

7 Qualification and selection of carbon and low-alloy steels with resistance to SSC, SOHIC and SZC 7.1 Option 1 — Selection of SSC-resistant steels (and cast irons) using A.2 7.1.1

For pH2S < 0.3 kPa (0.05 psi) The selection of materials for SSC resistance for pH2S below 0.3 kPa (0.05 psi) is not considered in detail in this part of ANSI/NACE MR0175/ISO 15156. Normally, no special precautions are required for the selection of steels for use under these conditions, nevertheless, highly susceptible steels can crack. Additional information on factors affecting susceptibility of steels and attack by cracking mechanisms other than SSC is given in 7.2.1. 7.1.2 For pH2S ≥ 0.3 kPa (0.05 psi) If the partial pressure of H2S in the gas is equal to or greater than 0.3 kPa (0.05 psi), SSC-resistant steels shall be selected using A.2. NOTE 1 The steels described or listed in A.2 are considered resistant to SSC in oil and natural-gas production and natural-gas treatment plants. NOTE 2

Users concerned with the occurrence of SOHIC and/or SZC can refer to Option 2 (see 7.2.2).

NOTE 3

For HIC and SWC, see Clause 8.

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7.2 Option 2 — Selection of steels for specific sour-service applications or for ranges of sour service 7.2.1 7.2.1.1

Sulfide stress cracking General

Option 2 allows the user to qualify and select materials for sulfide stress cracking (SSC) resistance for specific sour-service applications or for ranges of sour service. For a given material, the limits of environmental and metallurgical variables defined for specific sour service or for a range of sour service by qualification in accordance with Option 2 may replace any limits of environmental and metallurgical variables listed for that material in A.2 (Option 1). The use of option 2 can require knowledge of both the in situ pH and the H2S partial pressure and their variations with time; see ANSI/NACE MR0175/ISO 15156-1.

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Option 2 facilitates the purchase of bulk materials, such as OCTG or line pipe, where the economic incentive to use materials not described nor listed in Annex A outweighs the additional qualification and other costs that can be incurred. Steels for other equipment may also be qualified. In some cases, this requires an agreement between the supplier and the equipment user with respect to test and acceptance requirements. Such agreements shall be documented. Option 2 can also facilitate fitness-for-purpose evaluations of existing carbon or low-alloy steel equipment exposed to sour-service conditions more severe than assumed in the current design. 7.2.1.2

SSC regions of environmental severity

The severity of the sour environment, determined in accordance with ANSI/NACE MR0175/ISO 15156-1, with respect to the SSC of a carbon or low-alloy steel shall be assessed using Figure 1. In defining the severity of the H2S-containing environment, the possibility of exposure to unbuffered, condensed aqueous phases of low pH during upset operating conditions or downtime, or to acids used for well stimulation and/or the backflow of stimulation acid after reaction should be considered.

Key X

H2S partial pressure, expressed in kilopascals

in situ pH

region 0

SSC region 1

SSC region 2

SSC region 3

NOTE 1 The discontinuities in the figure below 0.3 kPa (0.05 psi) and above 1 MPa (150 psi) partial pressure H2S reflect uncertainty with respect to the measurement of H 2S partial pressure (low H2S) and the steel’s performance outside these limits (for both low and high H2S). NOTE 2

Guidance on the calculation of H2S partial pressure is given in Annex C.

NOTE 3

Guidance on the calculation of pH is given in Annex D.

Figure 1 — Regions of environmental severity with respect to the SSC of carbon and low-alloy steels

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ANSI/NACE MR0175/ISO 15156-2:2015(E) 7.2.1.3

Region 0 — For pH2S < 0.3 kPa (0.05 psi)

Normally, no precautions are required for the selection of steels for use under these conditions. Nevertheless, a number of factors, as follows, that can affect a steel's performance in this region should be considered. — Steels that are highly susceptible to SSC and HSC can crack. — Steel's physical and metallurgical properties affect its inherent resistance to SSC and HSC; see Clause 6. — Very high-strength steels can suffer HSC in aqueous environments without H2S. Above about 965 MPa (140 ksi) yield strength, attention should be given to steel composition and processing to ensure that these steels do not exhibit SSC or HSC in region 0 environments. — Stress concentrations increase the risk of cracking. 7.2.1.4

SSC regions 1, 2 and 3

Referring to the regions of severity of the exposure as defined in Figure 1, steels for region 1 may be selected using A.2, A.3 or A.4; steels for region 2 may be selected using A.2 or A.3; and steels for region 3 may be selected using A.2. In the absence of suitable choices from Annex A, carbon and low-alloy steels may be tested and qualified for use under specific sour-service conditions or for use throughout a given SSC region. Testing and qualification shall be in accordance with ANSI/NACE MR0175/ISO 15156-1 and Annex B. Documented field experience may also be used as the basis for material selection for a specific sour-service application; see ANSI/NACE MR0175/ISO 15156-1. 7.2.2

SOHIC and SZC

The user should consider SOHIC and SZC, as defined in ANSI/NACE MR0175/ISO 15156-1, when evaluating carbon steels in plate form and their welded products for sour service in H2S-containing environments. NOTE The occurrence of these phenomena is rare and they are not well understood. They have caused sudden failures in parent steels (SOHIC) and in the HAZ of welds (SOHIC and SZC). Their occurrence is thought to be restricted to carbon steels. The presence of sulfur or oxygen in the service environment is thought to increase the probability of damage by these mechanisms.

7.3 Hardness requirements 7.3.1

General

The hardness of parent materials and of welds and their heat-affected zones play important roles in determining the SSC resistance of carbon and low alloy steels. Hardness control can be an acceptable means of obtaining SSC resistance. 7.3.2

Parent metals

If hardness measurements on parent metal are specified, sufficient hardness tests shall be made to establish the actual hardness of the steel being examined. Individual HRC readings exceeding the value permitted by this part of ANSI/NACE MR0175/ISO 15156 may be considered acceptable if the average of several readings taken within close proximity does not exceed the value permitted by this part of ANSI/NACE MR0175/ISO 15156 and no individual reading is greater than 2 HRC above the specified value. Equivalent requirements shall apply to other methods of hardness measurement when specified in this part of ANSI/NACE MR0175/ISO 15156 or referenced in a manufacturing specification.

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B.4 provides guidance on test methods and acceptance criteria to evaluate resistance to SOHIC and SZC.

ANSI/NACE MR0175/ISO 15156-2:2015(E) NOTE The number and location of hardness tests on parent metal are not specified in ANSI/NACE MR0175/ISO 15156.

For ferritic steels, EFC Publication 16 shows graphs for the conversion of hardness readings, from Vickers (HV) to Rockwell (HRC) and from Vickers (HV) to Brinell (HBW), derived from the tables of ASTM E140 and ISO 18265. Other conversion tables also exist. Users may establish correlations for individual materials. 7.3.3 7.3.3.1

Welds General

The metallurgical changes that occur on welding carbon and low-alloy steels affect their susceptibility to SSC, SOHIC and SZC. Processes and consumables should be selected in accordance with good practice and to achieve the required cracking resistance. Welding shall be carried out in compliance with appropriate codes and standards as agreed between the supplier and the purchaser. Welding procedure specifications (WPSs) and procedure qualification records (PQRs) shall be available for inspection by the equipment user. The qualification of welding procedures for sour service shall include hardness testing in accordance with 7.3.3.2, 7.3.3.3 and 7.3.3.4. 7.3.3.2

Hardness testing methods for welding procedure qualification

Hardness testing for welding procedure qualification shall normally be carried out using the Vickers HV 10 or HV 5 method in accordance with ISO 6507-1, or the Rockwell method in accordance with ISO 6508-1 using the 15N scale. NOTE For the purposes of this provision, ASTM E384 is equivalent to ISO 6507-1 and ASTM E18 is equivalent to ISO 6508-1.

The HRC method may be used for welding procedure qualification if the design stress does not exceed twothirds of SMYS and the welding procedure specification includes post-weld heat treatment. The use of the HRC method for welding procedure qualification in all other cases shall require the agreement of the equipment user. NOTE Hardness surveys using the Vickers or Rockwell 15N testing method produce a more detailed picture of weld hardness and its variations. Hardness surveys using the HRC testing method might not detect small zones in welds or HAZs where the hardness exceeds the acceptance criteria for the Vickers or Rockwell 15N testing method. The significance of such small hard zones is not well understood.

The use of other hardness testing methods shall require the agreement of the equipment user. The Vickers or Rockwell 15N hardness testing method shall be used for the qualification of alternative weldhardness acceptance criteria as permitted in 7.3.3.4. Hardness surveys for welding procedure qualification --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

7.3.3.3

Vickers hardness surveys shall be in accordance with Figure 2 for butt welds, Figure 3 for fillet welds and Figure 4 for repair and partial penetration welds. HRC surveys of butt welds shall be in accordance with Figure 5. Survey requirements for other joint configurations shall be developed from these figures. Hardness surveys for qualification of overlay welding procedures shall be in accordance with Figure 6.

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Dimensions in millimetres

Key A

weld heat-affected zone (visible after etching)

lines of survey

hardness impressions: Impressions 2, 3, 6, 7, 10, 11, 14, 15, 17 and 19 should be entirely within the heat-affected zone and located as close as possible to the fusion boundary between the weld metal and the heat-affected zone

The top line of survey should be positioned so that impressions 2 and 6 coincide with the heat-affected zone of the final run or change of profile of the fusion line associated with the final run.

Figure 2 — Butt-weld survey method for Vickers hardness measurement Dimensions in millimetres

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Key A

weld heat-affected zone (visible after etching)

line of survey

line of survey, parallel to line B and passing through the fusion boundary between the weld metal and the heat-affected zone at the throat

hardness impressions: Impressions 3, 6, 10 and 12 should be entirely within the heat-affected zone and located as close as possible to the fusion boundary between the weld metal and the heat-affected zone

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Dimensions in millimetres

Key A

original weld heat-affected zone

repair-weld heat-affected zone

parallel lines of survey

hardness impressions: Impressions in the heat-affected zone should be located as close as possible to the fusion boundary

The top line of survey should be positioned so that the heat-affected zone impressions coincide with the heat-affected zone of the final run or change in profile of the cap of fusion line associated with the final run.

Figure 4 â&#x20AC;&#x201D; Repair and partial penetration welds

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

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Dimensions in millimetres

Key A

weld

weld heat-affected zone (visible after etching)

parent metal

lines of survey

hardness impressions: Impressions in the weld heat-affected zone should be located within 2 mm of the fusion boundary

Figure 5 â&#x20AC;&#x201D; Butt weld survey method for Rockwell hardness measurements

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Dimensions in millimetres

Key A

weld heat-affected zone (visible after etching)

lines of hardness survey indentations 1 to 12

layer of weld overlay (visible after etching)

hardness impressions

The Rockwell C hardness measurement method may be used subject to the requirements of 7.3.3.2. HRC hardness impressions in the HAZ shall be located within 2 mm of the fusion boundary. a

Using the Vickers or Rockwell 15N measurement methods, hardness impressions 2, 6 and 10 should be entirely within the heat-affected zone and located as close as possible to, but no more than 1 mm from, the fusion boundary between the weld overlay and HAZ.

Figure 6 â&#x20AC;&#x201D; Weld overlay 7.3.3.4

Hardness acceptance criteria for welds

Weld hardness acceptance criteria for steels selected using option 1 (see 7.1) shall be as specified in A.2.1.4. Alternative weld hardness acceptance criteria may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B. Weld-hardness acceptance criteria for steels qualified and/or selected using option 2 (see 7.2) may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B.

7.4 Other fabrication methods For steels that are subject to hardness change caused by fabrication methods other than welding, hardness testing shall be specified as part of the qualification of the fabrication process. Hardness testing shall be specified as part of the qualification of burning/cutting processes if any HAZ remains in the final product. The requirements, interpreted for the fabrication method, and hardness acceptance criteria of 7.3 shall apply. The form and location of the samples for evaluation and testing shall be acceptable to the equipment user.

8 Evaluation of carbon and low alloy steels for their resistance to HIC/SWC The equipment user shall consider HIC/SWC as defined in ANSI/NACE MR0175/ISO 15156-1 when evaluating flat-rolled carbon steel products for sour service environments containing even trace amounts of H2S and shall consider HIC/SWC testing of these products. Annex B provides guidance on test methods and acceptance criteria to evaluate resistance to HIC/SWC.

ÂŠ NACE/ISO 2015

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ANSI/NACE MR0175/ISO 15156-2:2015(E) The probability of HIC/SWC is influenced by steel chemistry and manufacturing route. The level of sulfur in the steel is of particular importance, typical maximum acceptable levels for flat-rolled and seamless products are 0.003 % mass fraction and 0.01 % mass fraction, respectively. Conventional forgings with sulfur levels less than 0.025 % mass fraction, and castings, are not normally considered sensitive to HIC or SOHIC. NOTE 1 HIC/SWC leading to loss of containment has occurred only rarely in seamless pipe and other products that are not flat-rolled. Furthermore, seamless pipe manufactured using modern technology is much less sensitive to HIC/SWC than older products. Hence, there can be benefits in evaluating seamless pipe for HIC/SWC resistance for applications where the potential consequences of failure make this justifiable. NOTE 2 The presence of rust, sulfur, or oxygen, particularly together with chloride, in the service environment is thought to increase the probability of damage.

9 Marking, labelling, and documentation Materials complying with this part of ANSI/NACE MR0175/ISO 15156 shall be made traceable, preferably by marking, before delivery. Suitable labelling or documentation is also acceptable.

The equipment user may request the equipment or materials supplier to provide documentation of the materials used in equipment or components and their environmental service limits as defined in this part of ANSI/NACE MR0175/ISO 15156. Table E.1 and Table E.2 provide designations that may be used to identify materials.

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For materials qualified and selected for a special application in accordance with Annex B, traceability shall include reference to the environmental conditions of the special application.

ANSI/NACE MR0175/ISO 15156-2:2015(E)

Annex A (normative) SSC-resistant carbon and low alloy steels (and requirements and recommendations for the use of cast irons)

A.1 General This annex describes and lists SSC-resistant carbon and low alloy steels. Requirements for the use of cast irons are given in A.2.4. Steels complying with this annex might not resist SOHIC, SZC, HIC or SWC without the specification of additional requirements (see 7.2.2 and/or Clause 8). NOTE

A.2 is consistent with the previously established requirements of NACE MR0175.

At the time of publication of this part of ANSI/NACE MR0175/ISO 15156, there are no listings of steels approved for SSC region 2 (A.3) or SSC region 1 (A.4). Therefore, A.3 and A.4 indicate only properties typical of steels that are expected to be suitable for use under the defined conditions.

A.2 SSC-resistant carbon and low-alloy steels and the use of cast irons A.2.1 General requirements for carbon and low alloy steels A.2.1.1 General --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Carbon and low-alloy steels shall comply with A.2.1.2 through A.2.1.9. Carbon and low-alloy steels, products and components that comply with A.2 are, with stated exceptions, qualified in accordance with this part of ANSI/NACE MR0175/ISO 15156 without further SSC testing. Nevertheless, any SSC testing that forms part of a materials manufacturing specification shall be carried out successfully and the results reported. The majority of steels that comply with the general requirements of A.2 are not individually listed; however, for convenience, some examples of such steels are listed in Table A.2, Table A.3 and Table A.4. NOTE 1 The carbon and low-alloy steels described/listed previously in NACE MR0175 (all revisions) were identified by extensive correlations of field failures/successes and laboratory data. The hardness limit of HRC 22 applied to most carbon and low-alloy steels is based on correlations of heat treatment, chemical composition, hardness and failure experience. The higher hardness limits for the chromium-molybdenum steels are based on similar considerations. NOTE 2 It can be possible to qualify a carbon or low alloy steel not described or listed in the text or tables of A.2 for use in specific sour service applications or for a range of sour service in accordance with Option 2 (7.2).

A.2.1.2 Parent metal composition, heat treatment and hardness Carbon and low-alloy steels are acceptable at 22 HRC maximum hardness provided they contain less than 1 % mass fraction nickel, are not free-machining steels and are used in one of the following heat-treatment conditions: a) hot-rolled (carbon steels only); b) annealed; c)

normalized; ÂŠ NACE/ISO 2015

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ANSI/NACE MR0175/ISO 15156-2:2015(E) d) normalized and tempered; e) normalized, austenitized, quenched, and tempered; f)

austenitized, quenched, and tempered.

A.2.1.3 Carbon steels acceptable with revised or additional restrictions In addition to the restrictions of A.2.1.2, some carbon steels are acceptable subject to the following revised or additional restrictions. a) Forgings produced in accordance with ASTM A105 are acceptable if the hardness does not exceed 187 HBW. b) Wrought pipe fittings to ASTM A234, grades WPB and WPC are acceptable if the hardness does not exceed 197 HBW. A.2.1.4 Welding Welding and weld-hardness determinations shall be performed in accordance with 7.3.3. Acceptable maximum hardness values for carbon steel, carbon manganese steel and low alloy steel welds are given in Table A.1. As-welded carbon steels, carbon-manganese steels and low-alloy steels that comply with the hardness requirements of Table A.1 do not require post-weld heat treatment. Tubular products with an SMYS not exceeding 360 MPa (52 ksi) and listed in Table A.2 are acceptable in the as-welded condition. For these products, hardness testing of welding procedures may be waived if agreed by the equipment user. Some tubular products with an SMYS exceeding 360 MPa (52 ksi) (see A.2.2.2) may be acceptable in the aswelded condition if suitable qualified welding procedures are used. The conditions in Table A.1 shall be met. Carbon steel, carbon manganese and low-alloy steel weldments that do not comply with other paragraphs of this subclause shall be post weld heat treated after welding. The heat treatment temperature and its duration shall be chosen to ensure that the maximum weld zone hardness, determined in accordance with 7.3, shall be 250 HV or, subject to the restrictions described in 7.3.3, 22 HRC. A minimum post weld heat treatment temperature of 620 °C (1 150 °F) shall be used for low alloy steels. --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

The acceptability of any effects on mechanical properties, other than hardness, caused by the chosen heat treatment and its duration shall be subject to the approval of the equipment user. Welding consumables and procedures that produce a deposit containing more than 1 % mass fraction nickel are acceptable after successful weld SSC qualification by testing in accordance with Annex B.

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Table A.1 — Maximum acceptable hardness values for carbon steel, carbon-manganese steel and low-alloy steel welds Hardness test methods

Hardness test locations for welding procedure qualification Weld root: Base metal, HAZ and weld root metal as shown in Figure 2, Figure 3 or Figure 4

Vickers HV 10 or HV 5 or Rockwell HR 15N

Base metal and HAZ for weld overlays as shown in Figure 6; see also A.2.1.5 b) Weld cap:

250 HV 70.6 HR 15N 250 HV 70.6 HR 15N 275 HVa

Base metal, HAZ and weld metal of unexposed weld cap as shown in Figure 2 or Figure 4 Rockwell HRC; see 7.3.3.2

Maximum acceptable hardness

73.0 HR 15N

As shown in Figure 5

22 HRC

Base metal and HAZ for weld overlays as shown in Figure 6; see also A.2.1.5 b)

22 HRC

The maximum shall be 250 HV or 70.6 HR 15N unless all three of the following conditions are met: — equipment user agrees the alternative weld cap hardness limit; — parent material(s) are over 9 mm thick; — weld cap is not exposed directly to the sour environment.

A.2.1.5 Surface treatments, overlays, plating, coatings, linings, etc. NOTE

The composition and cracking resistance of overlays are addressed in ANSI/NACE MR0175/ISO 15156-3.

Metallic coatings (electroplated and electroless plated), conversion coatings, plastic coatings and linings are not acceptable for preventing SSC. Overlays applied by thermal processes such as welding, silver brazing, or spray metallizing systems are acceptable if they comply with one of the following requirements. a) The heat-treated condition of the substrate is unchanged, i.e. it does not exceed the lower critical temperature during application of the overlay. b) The maximum hardness and final heat-treated condition of the base metal substrate comply with A.2.1.2 and, in the case of welded overlays, A.2.1.4. This requirement may be waived in accordance with ANSI/NACE MR0175/ISO 15156-3:2015, A.13.1. The maximum hardness and/or other properties of the weld deposit shall comply with the requirements of ANSI/NACE MR0175/ISO 15156-3 or this part of ANSI/NACE MR0175/ISO 15156, as applicable. --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Joining of dissimilar materials, such as cemented carbides to steels by silver brazing, is acceptable. The base metal after brazing shall comply with A.2.1.2. Nitriding, with a maximum case depth of 0.15 mm (0.006 in), is an acceptable surface treatment if conducted at a temperature below the lower critical temperature of the alloy being treated. A.2.1.6 Cold deformation and thermal stress relief Carbon and low-alloy steels shall be thermally stress-relieved following any cold deforming by rolling, cold forging or other manufacturing process that results in a permanent outer fibre deformation greater than 5 %. Thermal stress relief shall be performed in accordance with an appropriate code or standard. The minimum stress-relief temperature shall be 595 °C (1 100 °F). The final maximum hardness shall be 22 HRC except for pipe fittings made from ASTM A234 grade WPB or WPC, for which the final hardness shall not exceed 197 HBW. © NACE/ISO 2015

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ANSI/NACE MR0175/ISO 15156-2:2015(E) The above requirement does not apply to cold work imparted by pressure testing according to an applicable code or standard agreed by the equipment user. Cold-rotary straightened pipe is acceptable only where permitted in the applicable ISO or API product standards; see also A.2.2.3.4. Cold-worked line pipe fittings of ASTM A53 Grade B, ASTM A106 Grade B, API 5L Grade X-42, ISO 3183 Grade L290, or lower-yield-strength grades with similar chemical compositions, are acceptable with cold strain equivalent to 15 % or less, provided the hardness in the strained area does not exceed 190 HBW. SSC testing and qualification in accordance with Annex B may be used to justify other cold deformation limits. A.2.1.7 Threading Threads produced using a machine-cutting process are acceptable. Threads produced by cold forming (rolling) are acceptable in steels that otherwise comply with the heat treatment and hardness requirements of A.2.1.2. A.2.1.8 Cold deformation of surfaces Cold deformation of surfaces is acceptable if caused by processes, such as burnishing, that do not impart more cold work than that incidental to normal machining operations (such as turning, boring, rolling, threading, drilling, etc.). Cold deformation by controlled shot-peening is acceptable if applied to base materials that comply with this part of ANSI/NACE MR0175/ISO 15156 and if restricted to a maximum shot size of 2.0 mm (0.080 in) and an Almen intensity not exceeding 10C. The process shall be controlled in accordance with SAE AMS-2430. A.2.1.9 Identification stamping The use of identification stamping using low-stress (dot-, vibratory-, and round V-) stamps is acceptable. The use of conventional sharp V-stamping is acceptable in low-stress areas, such as the outside diameter of flanges. Conventional sharp V-stamping shall not be performed in high-stress areas unless subsequently stressrelieved at a minimum temperature of 595 °C (1 100 °F). A.2.2 Application to product forms A.2.2.1 General --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Except as modified below, the general requirements of A.2.1 shall apply to all product forms. A.2.2.2 Pipe, plate, and fittings Examples of tubular products that can comply with A.2.1 are shown in Table A.2. Pressure vessel steels classified as P-No 1, Group 1 or 2, in Section IX of the ASME Boiler and Pressure Vessel Code are acceptable. Products made from flat-rolled steels in contact with trace amounts of H2S [i.e. even if pH2S is below 0.3 kPa (0.05 psi)] can be susceptible to HIC/SWC damage.

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Table A.2 — Examples of tubular products that can comply with A.2.1 ISO specifications and grades

Other designations

ISO 3183 grades: L245 through L450

API Specification 5L grades: A and B and X-42 through X-65 ASTM A53 ASTM A106 grades A, B and C ASTM A333 grades 1 and 6 ASTM A524 grades 1 and 2 ASTM A381 class 1, Y35 to Y65

Pipe seam welds shall comply with A.2.1. A.2.2.3 Downhole casing, tubing, and tubular components A.2.2.3.1 ISO and API grades of casing and tubing are acceptable for the temperature ranges given in Table A.3. A.2.2.3.2 Tubulars and tubular components made of Cr-Mo low-alloy steels (UNS G41XX0, formerly AISI 41XX, and modifications), if quenched and tempered in the tubular form, are acceptable if their hardness does not exceed 30 HRC and they have SMYS grades of 690 MPa (100 ksi), 720 MPa (105 ksi), and 760 MPa (110 ksi). The maximum yield strength for each grade shall be no more than 103 MPa (15 ksi) higher than the SMYS. SSC resistance shall be demonstrated by testing each test batch and shall comply with B.1 using the UT test. A.2.2.3.3 Tubulars and tubular components made of Cr-Mo low-alloy steels (UNS G41XX0, formerly AISI 41XX and modifications), if quenched and tempered in the tubular form, are acceptable if the hardness does not exceed 26 HRC. These products should be qualified by SSC testing in accordance with B.1 using the UT test. A.2.2.3.4 If tubulars and tubular components are cold-straightened at or below 510 °C (950 °F), they shall be stress-relieved at a minimum temperature of 480 °C (900 °F). If tubulars and tubular components are cold-formed (pin-nosed and/or box-expanded) and the resultant permanent outer fibre deformation is greater than 5 %, the cold-formed regions shall be thermally stress-relieved at a minimum temperature of 595 °C (1 100 °F). If the connections of high-strength tubulars with hardnesses above 22 HRC are cold-formed, they shall be thermally stress-relieved at a minimum temperature of 595 °C (1 100 °F).

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Table A.3 — Environmental conditions for which grades of casing and tubing are acceptable For all temperatures ISO 11960a grades: H40 J55 K55 M65 L80 type 1 C90 type 1 T95 type 1

For ≥ 65 °C (150 °F) ISO 11960a grades: N80 type Q C95

Proprietary grades as described in A.2.2.3.3

Proprietary Q&T grades with 760 MPa (110 ksi) or less maximum yield strength

For ≥ 80 °C (175 °F) ISO 11960a grades: N80 P110

For ≥ 107 °C (225 °F) ISO 11960a grade: Q125b

Proprietary Q&T grades with 965 MPa (140 ksi) or less maximum yield strength

Casings and tubulars made of Cr-Mo low-alloy steels as described in A.2.2.3.2. Temperatures given are minimum allowable service temperatures with respect to SSC. Low temperature toughness (impact resistance) is not considered, equipment users shall determine requirements separately. a

For the purposes of this provision, API 5CT is equivalent to ISO 11960:2001.

Types 1 and 2 based on Q&T, Cr-Mo chemistry to 1 036 MPa (150 ksi) maximum yield strength. C-Mn steels are not acceptable. b

A.2.2.4 Bolting and fasteners Bolting that can be exposed directly to a sour environment, or that is buried, insulated, equipped with flange protectors or otherwise denied direct atmospheric exposure, shall conform to the general requirements of A.2.1. Designers and users should be aware that it can be necessary to lower equipment pressure ratings when using SSC-resistant bolting and fasteners. The use of SSC-resistant bolting and fasteners with API flanges shall be in accordance with ISO 10423. Table A.4 — Acceptable bolting materials Bolts ASTM A193 grade B7M ASTM A320 grade L7M

Nuts ASTM A194 grades 2HM, 7M

A.2.3 Application to equipment A.2.3.1 General The general requirements of A.2.1 apply, with the following modifications. A.2.3.2 Drilling blowout preventers A.2.3.2.1 Shear blades The high-strength steels used for blowout-preventer (BOP) shear blades can be susceptible to SSC. The suitability of shear blades that do not comply with this annex is the responsibility of the equipment user. A.2.3.2.2 Shear rams

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Rams manufactured in quenched and tempered Cr-Mo low-alloy steels (UNS G41XX0, formerly AISI 4IXX, and modifications) are acceptable if the hardness does not exceed 26 HRC. If the hardness of these alloys exceeds 22 HRC, careful attention shall be paid to chemical composition and heat treatment to ensure their SSC resistance. SSC testing, as agreed with the equipment user, shall demonstrate that the performance of the alloy meets or exceeds that of field proven material. A.2.3.2.3 Drilling, well construction and well-servicing equipment exposed only to drilling fluids of controlled composition Given the high strength often needed, drilling equipment might not comply with ANSI/NACE MR0175/ISO 15156 (all parts). In such cases, the primary means for avoiding SSC is control of the drilling or well-servicing environment. As service stresses and material hardness increase, drilling-fluid control becomes increasingly important. Care shall be taken to control the drilling environment by maintenance of drilling-fluid hydrostatic head and fluid density to minimize formation-fluid in-flow and by the use of one or more of the following: a) maintenance of pH 10 or higher to neutralize H2S in the drilled formation; b) use of chemical sulfide scavengers; c)

use of a drilling fluid in which oil is the continuous phase.

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A.2.3.3 Compressors and pumps A.2.3.3.1 Compressor impellers UNS G43200 (formerly AISI 4320) and a modified version of UNS G43200 that contains 0.28 % mass fraction to 0.33 % mass fraction carbon are acceptable for compressor impellers at a maximum yield strength of 620 MPa (90 ksi) provided they have been heat-treated in accordance with the following threestep procedure. a) Austenitize and quench. b) Temper at 620 °C (1 150 °F) minimum temperature, but below the lower critical temperature. Cool to ambient temperature before the second temper. c)

Temper at 620 °C (1 150 °F) minimum, but lower than the first tempering temperature. Cool to ambient temperature.

A.2.3.3.2 Special provisions for compressors and pumps Soft carbon steel and soft, low-carbon iron are acceptable as gaskets. Cast irons in accordance with A.2.4 are acceptable. A.2.4 Requirements for the use of cast irons A.2.4.1 General Grey, austenitic and white cast irons shall not be used for pressure-containing parts. These materials may be used for internal components if their use is permitted by the equipment standard and has been approved by the equipment user. Ferritic ductile iron in accordance with ASTM A395 is acceptable for equipment unless otherwise specified by the equipment standard. A.2.4.2 Packers and subsurface equipment The listed cast irons are acceptable for the following applications.

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Table A.5 â&#x20AC;&#x201D; Cast irons acceptable for packers and other subsurface equipment Component Drillable packer components

Cast iron Ductile iron (ASTM A536, ASTM A571/A571M) Malleable iron (ASTM A220, ASTM A602)

Compression members

Grey iron (ASTM A48, ASTM A278)

A.2.4.3 Compressors and pumps Grey cast iron (ASTM A278, Class 35 or 40) and ductile (nodular) cast iron (ASTM A395) are acceptable as compressor cylinders, liners, pistons and valves.

A.3 SSC-resistant steels for use throughout SSC region 2 The steels listed in A.2 are acceptable. The properties of steels typical of those that have been shown to meet the requirements for sour service throughout SSC region 2 are described below. Qualification according to Annex B shall be performed for steels that do not comply with A.2. A.3.2 Downhole casing, tubing, and tubular components Casing, tubing and tubular components made of Cr-Mo low-alloy steels (UNS G41XX0, formerly AISI 41XX, and modifications) have proven acceptable in the quenched and tempered condition. Typically, the actual yield strength of acceptable steels has been no more than 760 MPa (110 ksi) [an SMYS of approximately 550 MPa (80 ksi)] and their hardness has been no more than 27 HRC. Other requirements shall be in accordance with the applicable manufacturing specification. A.3.3 Pipeline steels Pipeline steels require appropriate restricted chemistries to ensure good weldability. Typically, SMYSs of up to 450 MPa (65 ksi) have proven acceptable. Typically, fabrication and field weld hardness should not exceed 280 HV. Other requirements shall be in accordance with the applicable manufacturing specification.

A.4 SSC-resistant steels for use throughout SSC region 1 A.4.1 General Steels listed in A.2 and A.3 are acceptable. The properties of steels typical of those that have been shown to meet the requirements for sour service throughout SSC region 1 are described below. Qualification according to Annex B shall be performed for steels which do not comply with A.2 or A.3. A.4.2 Downhole casing, tubing, and tubular components Casing, tubing and tubular components made of Cr-Mo low-alloy steels (UNS G41XX0, formerly AISI 41XX and modifications) have proven acceptable in the quenched and tempered condition. Typically, the actual yield strength of acceptable steels has been no more than 896 MPa (130 ksi) [an SMYS of approximately 760 MPa (110 ksi)] and their hardness has been no more than 30 HRC. Other requirements shall be in accordance with the applicable manufacturing specification. A.4.3 Pipeline steels Pipeline steels require appropriate restricted chemistries to ensure good weldability. Typically, SMYSs of up to 550 MPa (80 ksi) have proven acceptable. Typically, fabrication and field weld hardness should not exceed 300 HV. Other requirements shall be in accordance with the applicable manufacturing specification.

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A.3.1 General

ANSI/NACE MR0175/ISO 15156-2:2015(E)

Annex B (normative) Qualification of carbon and low-alloy steels for H2S service by laboratory testing

B.1 Requirements This annex specifies requirements for qualifying carbon and low-alloy steels for H2S service by laboratory testing. Requirements are given for qualifying resistance to the following cracking mechanisms. a) SSC qualification by laboratory testing shall require one or more of the following: — SSC testing in accordance with the materials manufacturing specification; see also A.2.1.1; — testing for specific sour service applications in accordance with B.3; — testing for SSC regions 1 or 2 of Figure 1 in accordance with B.3 and Note g of Table B.1; — testing for sour service in all SSC regions of Figure 1 in accordance with B.3. The qualification tests summarized demonstrate varying levels of resistance to SSC in sour environments. Some carbon and low-alloy steels described or listed in A.2 might not pass some of the laboratory test requirements listed above (see A.2.1). b) SZC and SOHIC qualification shall require testing in accordance with B.4 using appropriate environmental conditions from those specified for SSC qualification. c)

HIC and SWC shall be qualified as follows: — in any service environment (see B.5 and Table B.3); — in specific sour service applications (see B.5 and Table B.3).

In all cases, the equipment user shall ensure that the testing chosen is appropriate to the conditions of the intended service(s). The acceptance of the testing chosen shall be documented.

B.2 Uses of laboratory qualifications B.2.1 General

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An overview of the alternative uses of laboratory qualifications is given in Figure B.1.

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This part of ANSI/NACE MR0175/ISO 15156 addresses SSC, HIC, SOHIC and SZC of carbon and low-alloy steels. ANSI/NACE MR0175/ISO 15156-3 addresses SSC, SCC and galvanically induced hydrogen stress cracking (GHSC) of corrosion-resistant alloys (CRAs) and other alloys.

Annex A addresses SSC of carbon and low-alloy steels. ANSI/NACE MR0175/ISO 15156-3:2015, Annex A addresses SSC, SCC and GHSC of CRAs and other alloys.

See final paragraphs of “Introduction” for further information regarding document maintenance.

NOTE

Flowchart omits qualification by field experience as described in ANSI/NACE MR0175/ISO 15156-1.

Figure B.1 — Alternatives for alloy selection and laboratory qualification B.2.2 Qualification of manufactured products The user of this part of ANSI/NACE MR0175/ISO 15156 shall define the qualification requirements for the material in accordance with ANSI/NACE MR0175/ISO 15156-1 and this annex. This definition shall include the application of the following: a) general requirements (see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 5); b) evaluation and definition of service conditions (see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 6); c) material description and documentation (see ANSI/NACE MR0175/SO 15156-1:2015, 8.1); d) requirements for qualification based on laboratory testing (see ANSI/NACE MR0175/ISO 151561:2015, 8.3);

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

ANSI/NACE MR0175/ISO 15156-2:2015(E) e) report of the method of qualification (see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 9). Appropriate test batches and sampling requirements shall be defined with regard for the nature of the product, the method of manufacture, testing required by the manufacturing specification and the required qualification(s) (SSC, SOHIC, SZC, HIC/SWC). Samples shall be tested in accordance with Annex B for each cracking mechanism being qualified. A minimum of three specimens shall be tested per test batch. The test batch shall be qualified if all specimens satisfy the test acceptance criteria. Re-testing is permitted as follows. If a single specimen fails to satisfy the acceptance criteria, the cause shall be investigated. If the source material conforms to the manufacturing specification, two further specimens may be tested. These shall be taken from the same source as the failed specimen. If both satisfy the acceptance criteria, the test batch shall be considered qualified. Further retests shall require the purchaser’s agreement. Testing of manufactured products may be carried out at any time after manufacture and before exposure to H2S service. Before the products are placed in H2S service, the equipment user shall review the qualification and verify that it satisfies the defined qualification requirements. Products with a qualification that has been verified by the equipment user may be placed into H2S service. B.2.3 Qualification of a manufacturing source and route

A qualified production route may be followed to avoid order-release testing for H2S-cracking resistance.

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A defined production route may be qualified for the production of qualified material. A materials supplier may propose to a materials purchaser that a qualified production route be used to produce qualified materials. The qualified production route may be used if the materials supplier and materials purchaser agree to its use. A qualified production route may be used to produce qualified material for more than one materials user.

To qualify a production route, the material supplier shall demonstrate that a defined production route is capable of consistently manufacturing material that satisfies the applicable qualification test requirements of Annex B. The qualification of a production route requires all of the following: a) definition of the production route in a written quality plan that identifies the manufacturing location(s), all manufacturing operations and the manufacturing controls required to maintain the qualification; b) initial testing of products produced on the defined production route in accordance with B.2.2, with verification that they satisfy the acceptance criteria; c)

Periodic testing to confirm that the product continues to have the required resistance to cracking in H2S service; the frequency of “periodic” testing shall be defined in the quality plan and shall be acceptable to the purchaser; a record of such tests shall be available to the purchaser;

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ANSI/NACE MR0175/ISO 15156-2:2015(E) — Laboratory testing for the evaluation of carbon and low-alloy steels for addition to Annex A is for use with steels that do not comply with the general requirements described in A.2.1. — Addition of a carbon or low-alloy steel to A.2 requires the testing described in Table B.1 for all SSC regions of Figure 1 (see 7.2). — Addition of a carbon or low-alloy steel to A.3 or A.4 requires the testing described in Table B.1 for the appropriate SSC region of Figure 1 (see 7.2). — The steel being qualified by laboratory testing shall be selected in accordance with ANSI/NACE MR0175/ISO 15156-1. — Material representing a minimum of three separately processed heats shall be tested for SSC resistance in accordance with B.3. — Sufficient data shall be provided to allow the members of ISO/TC 67 to assess the material and decide on the suitability of the material for inclusion into this part of ANSI/NACE MR0175/ISO 15156, by amendment or revision, in accordance with the ISO/IEC Directives, Part 1.

Qualification shall be in accordance with B.1 and, as appropriate, Table B.1. Unless otherwise indicated, test requirements shall be in accordance with NACE TM0177. Generally, testing is performed at ambient temperature [24 °C ± 3 °C (75 °F ± 5 °F)]. For testing at elevated temperatures, reference may be made to the guidance on test environments given in ANSI/NACE MR0175/ISO 15156-3:2015, Annex B. For materials testing to a materials manufacturing specification, reference should be made to the appropriate specification, and to A.1 and B.1.

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B.3 Test procedures to evaluate the resistance of carbon and low-alloy steels to SSC

ANSI/NACE MR0175/ISO 15156-2:2015(E) Table B.1 — SSC laboratory testing for sour service Qualification validityf

Test typeabi

Applied stresscd

H2S partial pressure

Environment

Acceptance criteria

Specific application, or SSC region 1 or region 2 of Figure 1

FPBj or CR

DCBh

≥90 % AYS

Not applicable

5 % mass fraction NaCl + 0.4 % mass fraction CH3COONa, pH adjusted to required value using HCl or NaOHe

Appropriate to intended application or SSC region

UT FPBj All SSC regions of Figure 1

or CR

DCBh

≥80 % AYS

Not applicable

NACE TM0177 Environment A (5 % mass fraction NaCl + 0.5 % mass fraction CH3COOH)

100 kPa (15 psi) in accordance with NACE TM0177

No SSC cracks in accordance with NACE TM0177 assessment method

Remarks Specific application or less severe environments. Region qualification subject to adequate “coverage”g

Assessment shall be in accordance with NACE TM0177. Acceptance criteria shall be by documented agreementk

Use as qualification at equipment user’s discretion and with documented justification

No SSC cracks in accordance with NACE TM0177 assessment method

—

Assessment shall be in accordance with NACE TM0177. Acceptance criteria shall be by documented agreementk

Use as qualification at equipment user’s discretion and with documented justification

The test types are as follows: — UT test in accordance with NACE TM0177, Method A; — FPB test in accordance with EFC Publication 16, Appendix 2; — CR test in accordance with NACE TM0177, Method C; — DCB test in accordance with NACE TM0177, Method D;

— Other test specimens, including full-size components, may be used when appropriate. Their use shall be by agreement between the purchaser and the supplier. FPB, CR or UT tests are preferred for the qualification of welding and joining procedures; see 7.3 and 7.4. For welded samples, specimens shall normally be taken transverse to welds; testing shall be based on the actual yield strength of the lowest yield strength parent metal; side 4-point bend testing may be used, subject to the agreement of the equipment user. For details of side bend tests, see NACE publication CORROSION/2000 Paper 128. For applications where a low service stress level, as a proportion of yield strength, is guaranteed, the test stress may be reduced to the maximum service stress. In such cases, the tests and acceptance criteria shall be agreed with the equipment user. Such agreements shall be documented. c

AYS indicates the actual yield strength of material in finished form at the test temperature. The AYS shall be as defined in the product specification or the 0.2 % proof stress (Rp0.2) determined as the “non-proportional elongation” in accordance d

with ISO 6892-1. For SSC tests with pH control, the pH value during tests should be less than or equal to the required value. Control to within a range of 0,1 pH units is achievable in practice. e

See ANSI/NACE MR0175/ISO 15156-1:2015, Clause 5, for more information regarding designs utilizing plastic design criteria. f

Testing under the conditions listed in Table B.2 provides qualification for use throughout a region.

For special cases, including components of heavy section or of complex shape, DCB tests may be used to support designs based on fracture mechanics. h

Test types are not necessarily equivalent and results might not be directly comparable.

When SOHIC and/or SZC evaluation of a test specimen are carried out, see 7.2.2, the requirements of this table and of B.4 shall be met. j

See ISO 11960 for information on tubing and casing grades C90 and T95.

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Table B.2 — Test conditions

Set of conditions for SSC region 1

Set of conditions for SSC region 2

3.5

—

4.0

0,3

—

4.5

5.5

100

6.5

100

—

B.4 Test procedures to evaluate the resistance of carbon and low-alloy steels to SOHIC and SZC B.4.1 General The test methods described in this annex have been used successfully to demonstrate sensitivity to SOHIC or SZC. Materials shall have been qualified with respect to SSC resistance for the design conditions prior to SOHIC/SZC evaluation. When evaluating welds, 7.3.3 shall also apply. The validity of the test results for conditions other than those evaluated is defined in ANSI/NACE MR0175/ISO 15156-1. Test methods described for SOHIC and SZC are not standardized. Alternative tests are under development. The equipment user may choose other tests at his discretion. The justification of the use of such tests shall be documented. B.4.2 Small-scale tests B.4.2.1 Specimen selection The test samples used to determine susceptibility to SOHIC/SZC shall be the apparently unfailed UT or FPB test specimens taken from successful SSC qualification testing. Steels selected using A.2 shall also undergo SSC testing according to B.1 prior to the SOHIC/SZC evaluation. For small-scale testing of welds, specimens shall be taken transverse to the weld. B.4.2.2 Evaluation and acceptance criteria for UT test specimens One of the following evaluations and acceptance criteria for UT test specimens shall apply. a) Heat the specimens to 150 °C and hold at that temperature for 2 h to remove absorbed hydrogen. Measure the tensile strength of the specimen. The tensile strength shall be not less than 80 % of the actual tensile strength of the material as determined on identical, previously unused, specimens. b) Make at least two metallographic sections parallel to the sample axis. Examine the sections for possible ladder-like HIC features and other cracks related to SOHIC or to the soft zones of a weld (SZC). No ladder-like HIC indications nor cracks exceeding a length of 0.5 mm in the through thickness direction are allowed.

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Required H2S partial pressures for tests kPa

ANSI/NACE MR0175/ISO 15156-2:2015(E) B.4.2.3 Evaluation and acceptance criteria for FPB test specimens A wet-magnetic-particle examination shall be carried out on the side of the sample that was under tensile stress during H2S exposure. Below any magnetic particle indications running perpendicular to the stress axis, metallographic sectioning shall be made perpendicular to the indications or, in the absence of magnetic particle indications, at least two metallographic sections shall be made parallel to the stress axis of the specimen. Sections produced in these ways shall be examined for possible ladder-like HIC features and other cracks related to SOHIC or to the soft zones of a weld (SZC). No ladder-like HIC features nor cracks exceeding a length of 0.5 mm in the through thickness direction are allowed. To assist the detection of damage, specimens may be plastically deformed by 5 % in the previous bending direction prior to metallographic sectioning. Prior to deformation, the specimens shall be heated to 150 °C and maintained at that temperature for 2 h to remove absorbed hydrogen. Damage developed on the tensile side of a specimen in the form of blisters less than 1 mm below the surface, or on the compression side regardless of the depth of the blister, may be disregarded for the assessment of SOHIC/SZC but shall be reported. B.4.3 Full pipe ring tests Full pipe ring tests may be used. The document HSE OTI-95-635 describes a test and acceptance criteria. NOTE Residual stress has been shown to play an important role in the initiation of SOHIC and SZC. It is sometimes considered that such stresses in field situations are better represented in large-scale specimens.

B.5 Test procedures and acceptance criteria to evaluate the resistance of carbon and low-alloy steels to HIC/SWC Test procedures and acceptance criteria shall be in accordance with Table B.3. Testing shall be performed at ambient temperature [25 °C ± 3 °C (77 °F ± 5 °F)]. Unless otherwise indicated, test requirements shall be in accordance with NACE TM0284.

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Table B.3 — HIC/SWC test procedure and acceptance criteria Product type

Flat-rolled steels or their productsab

Applied stress

No applied stress

Environment

H2S partial pressure

Acceptance criteriae

Qualification validity

NACE TM0177 Environment A (5 % mass fraction NaCl + 0.5 % mass fraction CH3COOH)c

100 kPa (15 psi)c

CLR ≤ 15 % CTR ≤ 5 % CSR ≤ 2 %

Any sour service

5 % mass fraction NaCl + 0.4 % mass fraction CH3COONa, pH adjusted to required value using HCl or NaOHd

Appropriate to intended applicationd

No crackingg

Specific, or less severe dutyf

Qualification of seamless tubular products may also be appropriate; see Clause 8.

The samples being taken to represent the general performance of an order should be agreed between the producer and the equipment user. The sampling of materials for testing shall comply with ANSI/NACE MR0175/ISO 15156-1. b

The user is responsible for deciding whether this test environment is adequate to represent the severity of the intended application. c

Application-specific tests of steel for new or existing installations may be carried out. In such cases, tests of a duration longer than the standard 96 h (see NACE TM0284) may be applied at the equipment user’s discretion. Such tests may be required to improve confidence in the results obtained. d

At the request of the equipment user, ultrasonic evaluation of coupons may be used to find and evaluate areas of cracking prior to the selection of locations for metallurgical sectioning. See also EFC Publication 16, Section B7. Other acceptance criteria may be agreed between the supplier and the equipment user. Such agreements shall be documented. e

See ANSI/NACE MR0175/ISO 15156-1:2015, Clause 5, for further information regarding designs utilizing plastic design criteria. f

Other acceptance criteria may be used subject to the documented approval of the equipment user.

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Annex C (informative) Determination of H2S partial pressure

C.1 Calculation of partial pressure of H2S for systems with a gas phase The partial pressure of H2S, pH2S, expressed in megapascals (pounds per square inch), may be calculated by multiplying the system total pressure by the mole fraction of H2S in the gas phase as given in Formula (C.1): pH

= p´

(C.1)

100

where --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

is the system total absolute pressure, expressed in megapascals (pounds per square inch);

x H 2S is the mole fraction of H2S in the gas, expressed as a percentage.

For example, in a 70 MPa (10 153 psi) gas system, where the mole fraction of H2S in the gas is 10 %, the H2S partial pressure is 7 MPa (1 015 psi). If the system total pressure and concentration of H2S are known, H2S partial pressures can also be estimated using Figure C.1.

C.2 Calculations of effective H2S partial pressure for gas-free liquid systems For liquid systems (for which no equilibrium gas composition is available), the effective thermodynamic activity of H2S is defined by a virtual partial pressure of H2S that may be determined in the following way. a) Determine the bubble-point pressure, pB, of the fluid at operating temperature by any suitable method. NOTE For a liquid-full pipeline downstream of gas separation units, a good approximation for bubble-point pressure is the total pressure of the last gas separator.

b) Determine the mole fraction of H2S in the gas phase at bubble-point conditions by any suitable method. c)

Calculate the partial pressure of H2S, pH2S, expressed in megapascals (pounds per square inch), in the gas at the bubble point as given in Formula (C.2): pH

= pB ´

(C.2)

100

where pB

is the bubble-point pressure, expressed in megapascals (pounds per square inch);

x H 2S is the mole fraction of H2S in the gas, expressed as a percentage.

d) Use this as the H2S partial pressure for the liquid system. This value can be used to determine whether a system is sour in accordance with option 1 (see 7.1) or to determine its degree of sourness in accordance with option 2 (see 7.2).

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Key X

mole fraction H2S in gas, expressed in percent volume fraction times 104

NOTE

Percent volume fraction times 104 is the equivalent of the deprecated unit “parts per million by volume.”

total absolute pressure, expressed in megapascals

pH 2S = 0.3 kPa

pH 2S = 1 kPa

pH 2S = 10 kPa

pH 2S = 100 kPa

pH 2S = 1 000 kPa

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Figure C.1 — H2S partial pressure isobars in sour-gas systems

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Annex D (informative) Recommendations for determining pH

The use of Figure 1 requires the determination of in situ pH for the production conditions. Figures D.1 to D.5 (adapted from Reference [25]) give general guidance for the determination of an approximate pH value of the water phase for various conditions. pH determined in this way may be used if no proven calculation or reliable in situ measuring techniques are available. The likely error band may be taken as +00,5 pH units. In Figures D.1 to D.5, the ordinate axis is in situ pH. pH values routinely reported for depressurized water samples should not be mistaken as valid in situ pH values. The in situ pH can also be influenced by the presence of organic acids, such as acetic acid, propionic acid, etc. (and their salts), that are not considered in Figures D.1 to D.5. The importance of the influences of these acids on in situ pH and on the results of conventional water analyses are described in EFC Publication 17, Appendix 2. Analysis for these components should be made in order to make the necessary adjustments to the calculated in situ pH.

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Key 1

T = 20 °C

T = 100 °C

Figure D.1 — pH of condensed water under CO2 and H2S pressure

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Key 1

HCO -3 = 0 meq/l

HCO3 = 0.1 meq/l

HCO3 = 1 meq/l

HCO3 = 10 meq/l

HCO3 = 100 meq/l

T = 100 °C

T = 20 °C

Figure D.2 — pH of condensate water (wet gas) or formation waters containing bicarbonate (undersaturated in CaCO3) under CO2 and H2S pressure

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Key 1

Ca2+ = 1 000 meq/l

Ca2+ = 100 meq/l

Ca2+ = 10 meq/l

HCO -3 = 10 meq/l

HCO -3 = 30 meq/l

HCO -3 = 100 meq/l

Ca2+ < HCO 3

 Ca2+ = HCO3

Ca2+ > HCO3

Figure D.3 — pH of formation waters (super)saturated in CaCO3 (stoichiometric or nonstoichiometric) under CO2 and H2S pressure at 20 °C

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Key 1

Ca2+ = 1 000 meq/l

Ca2+ = 100 meq/l

Ca2+ = 10 meq/l

HCO -3 = 10 meq/l

HCO3 = 30 meq/l

HCO3 = 100 meq/l

Ca2+ < HCO 3

Ca2+ = HCO3

Ca2+ > HCO 3

Figure D.4 — pH of formation waters (super)saturated in CaCO3 (stoichiometric or nonstoichiometric) under CO2 and H2S pressure at 60 °C

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Key 1

Ca2+ = 1 000 meq/l

Ca2+ = 100 meq/l

Ca2+ = 10 meq/l

HCO3 = 10 meq/l

HCO3 = 30 meq/l

HCO -3 = 100 meq/l

Ca2+ < HCO 3

Ca2+ = HCO 3

Ca2+ > HCO 3

Figure D.5 — pH of formation waters (super)saturated in CaCO3 (stoichiometric or nonstoichiometric) under CO2 and H2S pressure at 100 °C

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

Annex E (informative) Information that should be supplied for material purchasing

Column 2 of Table E.1 and Table E.2 should be completed by the materials purchaser. Acceptable/required options should be indicated. NOTE The designation ANSI/NACE MR0175/ISO 15156-2A, in column 5, is generally equivalent to previously specifying carbon steels, low-alloy steels or cast irons in accordance with NACE MR0175.

Table E.1 — Minimum information for material purchasing Purchaser's reference Equipment type Preferred steel (or cast iron) type and/or grade Reference (sub)clause in ANSI/NACE MR0175/ISO 15156-2

Remarks

Sour-service designation ANSI/NACE MR0175/ ISO 15156-x, (multiple codes can be required)

Yes/No

7.1

—

Yes/No

7.2

If selected, see also 5.3 and Table E.2

—

If selected, see also 5.3 and Table E.2

—

Governing sour service specification: ANSI/NACE MR0175/ISO 15156 (all parts) Materials requirements for this purchase order

SSC resistance option 1: Carbon steel, low-alloy steel or cast iron for sour service selected from A.2 SSC resistance option 2: Carbon or low-alloy steel for specific sour-service applications or for ranges of sour service HIC resistance: (a) Material for any sour service?

Yes/No

(b) Material for specific sourservice applications or for ranges of sour service?

Yes/No

Clause 8 and B.5

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ANSI/NACE MR0175/ISO 15156-2:2015(E) Table E.2 — Additional information for SSC testing and other special cases Purchaser's reference Reference (sub)clause in ANSI/NACE MR0175/ ISO 15156-2

Remarks

Sour service designation ANSI/NACE MR0175/ ISO 15156-x, (multiple codes can be required)

7.2

—

7.2.1.4, Figure 1, Table B.1 and its Notes

UT test specimens by default

2R3

7.2.1.4, Figure 1 Table B.1 and its Notes

UT test specimens by default

2R2

7.2.1.4, Figure 1 Table B.1 and its Notes

UT test specimens by default

2R1

7.2.1.4, Table B.1 and its Notes

Test condition data below required. UT test specimens by default

Clause 8 and Table B.1

Test condition data below required

2HS

—

Table B.1 and/or Table B.3

Default values per Table B.1, other values require documented justification according to ANSI/NACE MR0175/ISO 15156-1

—

% AYS (or as appropriate)

—

CO2

—

MPa (psi)

—

H2S

—

MPa (psi)

—

Temperature

—

°C

—

For calculation of pH, see Annex D.

—

Cl− or other halide

—

mg/l

—

Elemental sulfur (S0)

—

Present or absent

—

Special requirements

—

Yes/No

7.2.2 and B.4

SSC testing always required before SOHIC/SZC testing

2Z with SSC designation from above

Materials requirements for this purchase order

Resistance to SSC following option 2

Indicate preferred options

a) Sour service for any SSC region? Test specimen type

Yes/No

b) Sour service for SSC regions 2 and 1?

Yes/No

Test specimen type c) Sour service for SSC region 1?

Yes/No

Test specimen type d) Specific sour service application required?

Yes/No

Test specimen type Resistance to HIC for specific sour service application?

Yes/No

Description of test conditions

Test stress for SSC testing

In situ pH

SOHIC and SZC resistance requirements

41 --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-2:2015(E)

[1]

ISO 3183, Petroleum and natural gas industries — Steel pipe for pipeline transportation systems

[2]

ISO 11960, Petroleum and natural gas industries — Steel pipes for use as casing or tubing for wells

[3]

ISO 18265, Metallic materials — Conversion of hardness values

[4]

API Spec 5CT, Specification for Casing and Tubing4

[5]

ANSI/API Spec 5L/ISO 3183, Specification for Line Pipe

[6]

ASME Boiler and Pressure Vessel Code, Section IX — Qualification Standard For Welding and Brazing Procedures, Welders, Brazers, and Welding and Brazing Operators5

[7]

ASTM A48/A 48M, Standard Specification for Gray Iron Castings 6

[8]

ASTM A53/A 53M, Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless

[9]

ASTM A105/A 105M, Standard Specification for Carbon Steel Forgings for Piping Applications

[10]

ASTM A106, Standard Specification for Seamless Carbon Steel Pipe for High-Temperature Service

[11]

ASTM A193/A193M, Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for High-Temperature Service or High Pressure Service and Other Special Purpose Applications

[12]

ASTM A194/A194M, Standard Specification for Carbon and Alloy Steel Nuts for Bolts for High Pressure or High Temperature Service, or Both

[13]

ASTM A220/A220M, Standard Specification for Pearlitic Malleable Iron

[14]

ASTM A234/A234M, Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel For Moderate and High Temperature Service

[15]

ASTM A278/A278M, Standard Specification for Gray Iron Castings for Pressure-Containing Parts for Temperatures up to 650 °F (350 °C)

[16]

ASTM A320/A320M, Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service

[17]

ASTM A333/A333M, Standard Specification for Seamless and Welded Steel Pipe for Low-Temperature Service and Other Applications with Required Notch Toughness

[18]

ASTM A381, Standard Specification for Metal-Arc-Welded Steel Pipe for Use With High-Pressure Transmission Systems

[19]

ASTM A395/A395M, Standard Specification for Ferritic Ductile Iron Pressure-Retaining Castings for Use At Elevated Temperatures

4 American Petroleum Institute, 1220 L Street NW, Washington, DC 20005-4070, USA. 5 ASME International, Three Park Avenue, New York, NY 10016-5990, USA. 6 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA.

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Bibliography

ANSI/NACE MR0175/ISO 15156-2:2015(E) ASTM A524, Standard Specification for Seamless Carbon Steel Pipe for Atmospheric and Lower Temperatures

[21]

ASTM A536, Standard Specification for Ductile Iron Castings

[22]

ASTM A571/A571M, Standard Specification for Austenitic Ductile Iron Castings for PressureContaining Parts Suitable for Low-Temperature Service

[23]

ASTM A602, Standard Specification for Automotive Malleable Iron Castings

[24]

ASTM E140, Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Rockwell Superficial Hardness, Knoop Hardness, and Scleroscope Hardness

[25]

BONIS M., CROLET J.-L. Practical aspects of the influence of in situ pH on H2S-induced cracking. Corros. Sci. 1987, 27 pp. 1059–1070

[26]

HSE OTI-95-635, A test method to determine the susceptibility to cracking of linepipe steels in sour service 7

[27]

NACE CORROSION/2000, Paper 128, A new device for side bend testing on pipe seam welds8

[28]

NACE MR0176, Metallic materials for sucker-rod pumps for corrosive oilfield environments

[29]

NACE MR0175, Sulfide stress cracking resistant metallic materials for oilfield equipment

[30]

SAE — ASTM, Metals and alloys in the unified numbering system, ISBN 0-7680-0407

[31]

ASTM E10, Standard Test Method for Brinell Hardness of Metallic Materials

[32]

ASTM E18, Standard Test Methods for Rockwell Hardness of Metallic Materials

[33]

ASTM E384, Standard Test Method for Knoop and Vickers Hardness of Materials

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[20]

UK Health and Safety Executive, HSE Books, PO Box 1999, Sudbury, Suffolk CO10 2WA, UK [ISBN 0-7176-1216-3].

NACE International, 15835 Park Ten Place, Houston, TX 77084-5145, USA. © NACE/ISO 2015

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Item No. 21307

International Standard ANSI/NACE MR0175/ISO 15156-3:2015

Petroleum, petrochemical, and natural gas industries — Materials for use in H2S-containing environments in oil and gas production — Part 3: Cracking-resistant CRAs (corrosionresistant alloys) and other alloys An American National Standard Approved November 23, 2015

Reference number ANSI/NACE MR0175/ISO 15156:2015 ©

ANSI/NACE/ISO 2015

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Contents

Page

Foreword ....................................................................................................................................................................... vii Introduction ................................................................................................................................................................... ix 1

Scope .................................................................................................................................................................... 1

Normative references .................................................................................................................................... 2

Terms and definitions ................................................................................................................................... 3

Symbols and abbreviated terms ................................................................................................................ 5

Factors affecting the cracking-resistance of CRAs and other alloys in H2S-containing environments.................................................................................................................................................... 5

6 6.1 6.2 6.2.1 6.2.2 6.2.3 6.3

Qualification and selection of CRAs and other alloys with respect to SSC, SCC, and GHSC in H2S-containing environments .................................................................................................... 6 General ................................................................................................................................................................ 6 Evaluation of materials properties ........................................................................................................... 6 Hardness of parent metals ........................................................................................................................... 6 Cracking-resistance properties of welds ................................................................................................ 7 Cracking-resistance properties associated with other fabrication methods ............................ 8 PREN ..................................................................................................................................................................... 8

7 7.1 7.2

Purchasing information and marking ..................................................................................................... 9 Information that should be supplied for material purchasing ....................................................... 9 Marking, labelling, and documentation .................................................................................................. 9

Annex A (normative) Environmental cracking-resistant CRAs and other alloys (including Table A.1 — Guidance on the use of the materials selection tables) ......................................... 10 A.1

General ............................................................................................................................................................. 10

A.1.2 Limits of chemical composition .............................................................................................................. 10 A.1.3 Environmental and metallurgical limits for cracking-resistance............................................... 11 A.1.4 Requirements and recommendations on welding ........................................................................... 11 A.1.5 Other requirements and recommendations on CRAs and other alloys .................................... 11 A.1.5.1 Requirements for overlays, surface treatments, plating, coatings, linings, etc. .................... 11

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A.1.1 Materials groups ........................................................................................................................................... 10

A.1.5.2 Threading ........................................................................................................................................................ 11 A.1.5.3 Cold deformation of surfaces ................................................................................................................... 12 A.1.5.4 Identification stamping .............................................................................................................................. 12 A.1.6 Use of materials selection tables ............................................................................................................ 12 A.2

Austenitic stainless steels (identified as material type and as individual alloys) ................ 12

A.2.1 Materials analyses........................................................................................................................................ 12 A.2.2 Environmental and materials limits for the uses of austenitic stainless steels .................... 14 A.2.3 Welding of austenitic stainless steels of this materials group ..................................................... 18

iii

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.3

Highly alloyed austenitic stainless steels (identified as material types and as individual alloys).......................................................................................................................................... 18

A.3.1 Materials chemical compositions ........................................................................................................... 18 A.3.2 Environmental and materials limits for the uses of highly alloyed austenitic stainless steels ................................................................................................................................................................. 19 A.3.3 Welding highly alloyed austenitic stainless steels of this materials group ............................ 22 A.4

Solid-solution nickel-based alloys (identified as material types and as individual alloys) ............................................................................................................................................................... 22

A.4.1 Materials chemical compositions ........................................................................................................... 22 A.4.2 Environmental and materials limits for the uses of solid-solution nickel-based alloys .... 23 A.4.3 Welding solid-solution nickel-based alloys of this materials group ......................................... 26 A.5

Ferritic stainless steels (identified as material type) ..................................................................... 27

A.5.1 Materials chemical compositions ........................................................................................................... 27 A.5.2 Environmental and materials limits for the uses of ferritic stainless steels .......................... 27 A.5.3 Welding of ferritic stainless steels of this materials group .......................................................... 27 A.6

Martensitic (stainless) steels (identified as individual alloys) ................................................... 27

A.6.1 Materials chemical compositions ........................................................................................................... 27 A.6.2 Environmental and materials limits for the uses of martensitic stainless steels ................. 28 A.6.3 Welding of martensitic stainless steels of this materials group ................................................. 33 A.7

Duplex stainless steels (identified as material types) .................................................................... 33

A.7.1 Materials chemical compositions ........................................................................................................... 33 A.7.2 Environmental and materials limits for the uses of duplex stainless steels .......................... 34 A.7.3 Welding of duplex stainless steels of this materials group ........................................................... 35 A.8

Precipitation-hardened stainless steels (identified as individual alloys) .............................. 36

A.8.1 Materials chemical compositions ........................................................................................................... 36 A.8.2 Environmental and materials limits for the uses of precipitation-hardened stainless steels ................................................................................................................................................................. 36 A.8.3 Welding of precipitation-hardened stainless steels of this materials group ......................... 42 A.9

Precipitation-hardened nickel-based alloys (identified as individual alloys) ...................... 42

A.9.1 Materials chemical compositions ........................................................................................................... 42 A.9.2 Environmental and materials limits for the uses of precipitation-hardened nickelbased alloys .................................................................................................................................................... 42 A.9.3 Welding of precipitation-hardened nickel-based alloys of this materials group ................. 50 A.10

Cobalt-based alloys (identified as individual alloys) ...................................................................... 50

A.10.1 Materials chemical compositions ........................................................................................................... 50 A.10.2 Environmental and materials limits for the uses of cobalt-based alloys ................................. 51 A.10.3 Welding of cobalt-based alloys of this materials group ................................................................. 53 A.11

Titanium and tantalum (individual alloys) ........................................................................................ 53

A.11.1 Materials chemical compositions ........................................................................................................... 53

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.11.1.1 Titanium alloys........................................................................................................................................... 53 A.11.1.2 Tantalum alloys.......................................................................................................................................... 53 A.11.2 Environmental and materials limits for the uses of titanium and tantalum alloys ............. 53 A.11.3 Welding of titanium and tantalum alloys of this materials group .............................................. 55 A.12

Copper- and aluminium-based alloys (identified as materials types) ...................................... 55

A.12.1 Copper-based alloys .................................................................................................................................... 55 A.12.2 Aluminium-based alloys ............................................................................................................................ 55 A.13

Cladding, overlays, and wear-resistant alloys ................................................................................... 55

A.13.1 Corrosion-resistant claddings, linings and overlays ....................................................................... 55 A.13.2 Wear-resistant alloys .................................................................................................................................. 56 A.13.2.1 Wear-resistant alloys used for sintered, cast, or wrought components................................ 56 A.13.2.2 Hard-facing materials .............................................................................................................................. 56 Annex B (normative) Qualification of CRAs for H2S-service by laboratory testing ............................. 57 B.1

General ............................................................................................................................................................. 57

B.2

Uses of laboratory qualifications ............................................................................................................ 59

B.2.1 General ............................................................................................................................................................. 59 B.2.2 Qualification of manufactured products .............................................................................................. 60 B.2.3 Qualification of a defined production route ....................................................................................... 60 B.2.4 Use of laboratory testing as a basis for proposing additions and changes to Annex A ....... 61 B.3

General requirements for tests ............................................................................................................... 61

B.3.1 Test method descriptions.......................................................................................................................... 61 B.3.2 Materials .......................................................................................................................................................... 61 B.3.3 Test methods and specimens ................................................................................................................... 62 B.3.4 Applied test stresses/loads for smooth specimens ......................................................................... 62 B.3.5 SSC/SCC test environments ....................................................................................................................... 62 B.3.5.1 General ............................................................................................................................................................. 62 B.3.5.2 Service simulation at actual H2S and CO2 partial pressures — Type 1 environments ........ 63 B.3.5.3 Service simulation at ambient pressure with natural buffering agent — Type 2 environments................................................................................................................................................. 64 B.3.5.4 Service simulation at ambient pressure with acetic buffer — Type 3a and Type 3b environments................................................................................................................................................. 64 B.3.6 Test duration.................................................................................................................................................. 64 B.3.7 Acceptance criteria and test report ....................................................................................................... 64 B.4

SSC testing ....................................................................................................................................................... 65

B.5

SCC testing without S0 ................................................................................................................................. 65

B.6

SSC/SCC testing at intermediate temperatures ................................................................................. 66

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B.3.8 Validity of tests .............................................................................................................................................. 65

ANSI/NACE MR0175/ISO 15156-3:2015(E) B.7

SCC testing in the presence of S0 ............................................................................................................. 66

B.8

GHSC testing with carbon steel couple ................................................................................................. 66

Annex C (informative) Information that should be supplied for material purchasing ...................... 67 Annex D (informative) Materials chemical compositions and other information............................... 69 Annex E (informative) Nominated sets of test conditions ............................................................................ 83

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Bibliography ................................................................................................................................................................. 84

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

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For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries. This third edition cancels and replaces the second edition (ANSI/NACE MR0175/ISO 15156-3:2009), which has been technically revised with the following changes: — replacement in the Scope of the term “conventional elastic design criteria” by the term “load controlled design methods”; — refinements to 6.3 to require the use of absolute values when FPREN is calculated for use in this part of ANSI/NACE MR0175/ISO 15156; — acceptance of the environmental limits for low carbon 300 series stainless steels also for their dual certified grades; — changes to some of the tables of Annex A to more conservatively reflect the current knowledge of the limits of use of some materials; — changes to the definition of acceptable limits to in situ production environment pH in some tables of Annex A; — additions to a number of tables of Annex A of new sets of acceptable environmental limits for (new) materials and their associated metallurgical requirements.

vii

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ANSI/NACE MR0175/ISO 15156-3:2015(E) ANSI/NACE MR0175/ISO 15156 consists of the following parts, under the general title Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas production: — Part 1: General principles for selection of cracking-resistant materials — Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons

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— Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Introduction The consequences of sudden failures of metallic oil and gas field components associated with their exposure to H2S-containing production fluids led to the preparation of the first edition of NACE MR0175 which was published in 1975 by the National Association of Corrosion Engineers, now known as NACE International. The original and subsequent editions of NACE MR0175 established limits of H 2S partial pressure above which precautions against sulfide stress cracking (SSC) were always considered necessary. They also provided guidance for the selection and specification of SSC-resistant materials when the H2S thresholds were exceeded. In more recent editions, NACE MR0175 has also provided application limits for some corrosion-resistant alloys in terms of environmental composition and pH, temperature, and H2S partial pressures. In separate developments, the European Federation of Corrosion issued EFC Publication 16 in 1995 and EFC Publication 17 in 1996. These documents are generally complementary to those of NACE, though they differed in scope and detail.

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In 2003, the publication of the ISO 15156 series and ANSI/NACE MR0175/ISO 15156 was completed for the first time. These technically identical documents utilized the above sources to provide requirements and recommendations for materials qualification and selection for application in environments containing wet H2S in oil and gas production systems. They are complemented by NACE TM0177 and NACE TM0284 test methods. The revision of this part of ANSI/NACE MR0175/ISO 15156 involves a consolidation of all changes agreed and published in the Technical Circular 1, ANSI/NACE MR0175/ISO 15156-3:2009/Cir.1:2011(E), Technical Circular 2, ANSI/NACE MR0175/ISO 15156-3:2009/Cir.2:2013(E), Technical Circular 3, ANSI/NACE MR0175/ISO 15156-3:2009/Cir.3:2014(E), and Technical Circular 4, ANSI/NACE MR0175/ ISO 15156-3:2009/Cir.4:2014(E), published by the ISO 15156 Maintenance Agency secretariat at DIN, Berlin. The changes were developed by and approved by the ballot of representative groups from within the oil and gas production industry. The great majority of these changes stem from issues raised by document users. A description of the process by which these changes were approved can be found at the ISO 15156 maintenance Web site: www.iso.org/iso15156maintenance. Technical Circular ANSI/NACE MR0175/ISO 15156-3:2009/Cir.2:2013 and Technical Circular ANSI/NACE MR0175/ISO 15156-3:2009/Cir.3:2014 intend that an informative Annex F should be published for this part of ANSI/NACE MR0175/ISO 15156 that was to give an alternative presentation of the information contained in the materials selection tables of Annex A. During final editing of this part of ANSI/NACE MR0175/ISO 15156, a number of technical errors were found in the transfer of information between the materials selection tables of Annex A and Table F.1. In order not to delay the publication of the new edition of this part of ANSI/NACE MR0175/ISO 15156, the ISO 15156 Maintenance Agency agreed that the proposed Annex F should not be published at this time. When found necessary by oil and gas production industry experts, future interim changes to this part of ANSI/NACE MR0175/ISO 15156 will be processed in the same way and will lead to interim updates to this part of ANSI/NACE MR0175/ISO 15156 in the form of Technical Corrigenda or Technical Circulars. Document users should be aware that such documents can exist and can impact the validity of the dated references in this part of ANSI/NACE MR0175/ISO 15156. The ISO 15156 Maintenance Agency at DIN was set up after approval by the ISO Technical Management Board given in document 34/2007. This document describes the make up of the agency which includes experts from NACE, EFC and ISO/TC 67, and the process for approval of amendments. It is available from the ANSI/NACE MR0175/ISO 15156 maintenance Web site and from the ISO/TC 67 Secretariat. The website also provides access to related documents that provide more detail on ANSI/NACE MR0175/ISO 15156 maintenance activities.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Petroleum, petrochemical, and natural gas industries – Materials for use in H2S-containing environments in oil and gas production – Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys WARNING — CRAs (corrosion-resistant alloys) and other alloys selected using this part of NACE MR0175/ISO 15156 are resistant to cracking in defined H2S-containing environments in oil and gas production, but not necessarily immune to cracking under all service conditions. It is the equipment user's responsibility to select the CRAs and other alloys suitable for the intended service.

1 Scope This part of ANSI/NACE MR0175/ISO 15156 gives requirements and recommendations for the selection and qualification of CRAs (corrosion-resistant alloys) and other alloys for service in equipment used in oil and natural gas production and natural gas treatment plants in H2S-containing environments whose failure can pose a risk to the health and safety of the public and personnel or to the environment. It can be applied to help avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the materials requirements of the appropriate design codes, standards, or regulations. This part of ANSI/NACE MR0175/ISO 15156 addresses the resistance of these materials to damage that can be caused by sulfide stress cracking (SSC), stress corrosion cracking (SCC), and galvanically induced hydrogen stress cracking (GHSC). This part of ANSI/NACE MR0175/ISO 15156 is concerned only with cracking. Loss of material by general (mass loss) or localized corrosion is not addressed. Table 1 provides a non-exhaustive list of equipment to which this part of ANSI/NACE MR0175/ISO 15156 is applicable, including permitted exclusions. This part of ANSI/NACE MR0175/ISO 15156 applies to the qualification and selection of materials for equipment designed and constructed using load-controlled design methods. For design utilizing strainbased design methods, see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 5. This part of ANSI/NACE MR0175/ISO 15156 is not necessarily suitable for application to equipment used in refining or downstream processes and equipment.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table 1 — List of equipment ANSI/NACE MR0175/ISO 15156 is applicable to materials used for the following equipment Drilling, well construction, and well-servicing equipment

Permitted exclusions Equipment exposed only to drilling fluids of controlled a composition Drill bits Blowout-preventer (BOP) shear blades

Drilling riser systems Work strings Wireline and wireline equipment

Surface and intermediate casing Wells including subsurface equipment, gas lift equipment, wellheads, and christmas trees

Sucker rod pumps and sucker rods

Electric submersible pumps Other artificial lift equipment Slips

Flow-lines, gathering lines, field facilities, and field processing plants

Crude oil storage and handling facilities operating at a total absolute pressure below 0.45 MPa (65 psi)

Water-handling equipment

Water-handling facilities operating at a total absolute pressure below 0.45 MPa (65 psi) Water injection and water disposal equipment

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Natural gas treatment plants

—

Transportation pipelines for liquids, gases, and multi-phase fluids

Lines handling gas prepared for general commercial and domestic use

For all equipment above

Components loaded only in compression

See ANSI/NACE MR0175/ISO 15156-2:2015, A.2.3.2.3 for more information.

See ANSI/NACE MR0175/ISO 15156-2:2015, A.2.3.2.1 for more information.

Wireline lubricators and lubricator connecting devices are not permitted exclusions.

For sucker rod pumps and sucker rods, reference can be made to NACE MR0176.

2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature ISO 7539-7, Corrosion of metals and alloys — Stress corrosion testing — Part 7: Method for slow strain rate testing

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ANSI/NACE MR0175/ISO 15156-3:2015(E) ISO 10423, Petroleum and natural gas industries — Drilling and production equipment — Wellhead and christmas tree equipment ISO 11960, Petroleum and natural gas industries — Steel pipes for use as casing or tubing for wells ANSI/NACE MR0175/ISO 15156-1:2015, Petroleum and natural gas industries — Materials for use in H2Scontaining environments in oil and gas production — Part 1: General principles for selection of crackingresistant materials ANSI/NACE MR0175/ISO 15156-2:2015, Petroleum and natural gas industries — Materials for use in H2Scontaining environments in oil and gas production — Part 2: Cracking-resistant carbon and low alloy steels, and the use of cast irons ASTM A747/A747M,1 Standard Specification for Steel Castings, Stainless, Precipitation Hardening ASTM E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications ASTM E562, Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count

NACE CORROSION/95,3 Paper 47, Test methodology for elemental sulfur-resistant advanced materials for oil and gas field equipment NACE CORROSION/97, Paper 58, Rippled strain rate test for CRA sour service materials selection NACE Standard TM0177, Laboratory testing of metals for resistance to sulfide stress cracking and stress corrosion cracking in H2S environments NACE Standard TM0198, Slow strain rate test method for screening corrosion resistant alloys (CRAs) for stress corrosion cracking in sour oilfield service SAE AMS-2430, Shot Peening, Automatic SAE4 — ASTM, Metals and alloys in the Unified Numbering System, ISBN 0-7680-04074

3 Terms and definitions For the purposes of this document, the terms and definitions given in ANSI/NACE MR0175/ISO 15156-1, ANSI/NACE MR0175/ISO 15156-2, and the following apply. 3.1 ageing change in metallurgical properties that generally occurs slowly at room temperature (natural ageing) and more rapidly at higher temperature (artificial ageing) 1 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA. 2 European Federation for Corrosion, available from The Institute of Materials, 1 Carlton House Terrace, London SW1Y 5DB, UK

[ISBN 0-901716-95-2]. 3 NACE International, 15835 Park Ten Place, Houston, TX 77084-5145, USA. 4 Society of Automotive Engineers (SAE), 400 Commonwealth Drive, Warrendale, PA 15096-0001, USA.

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EFC Publications Number 17,2 Corrosion resistant alloys for oil and gas production: guidelines on general requirements and test methods for H2S service

ANSI/NACE MR0175/ISO 15156-3:2015(E) 3.2 anneal heat to and hold at a temperature appropriate for the specific material and then cool at a suitable rate for such purposes as reducing hardness, improving machineability, or obtaining desired properties 3.3 austenite face-centred cubic crystalline phase of iron-based alloys 3.4 duplex stainless steel austenitic/ferritic stainless steel stainless steel (3.13) whose microstructure at room temperature consists primarily of a mixture of austenite (3.3) and ferrite (3.5) 3.5 ferrite body-centred cubic crystalline phase of iron-based alloys 3.6 ferritic stainless steel stainless steel (3.13) whose microstructure at room temperature consists predominantly of ferrite (3.5) 3.7 galvanically induced hydrogen stress cracking GHSC cracking that results due to the presence of hydrogen in a metal induced in the cathode of a galvanic couple and tensile stress (residual and/or applied) 3.8 martensite hard, supersaturated solid solution of carbon in iron characterized by an acicular (needle-like) microstructure 3.9 martensitic steel steel in which a microstructure of martensite (3.8) can be attained by quenching at a cooling rate fast enough to avoid the formation of other microstructures 3.10 pitting-resistance equivalent number PREN FPREN number developed to reflect and predict the pitting resistance of a CRA based upon the proportions of the elements Cr, Mo, W, and N in the chemical composition of the alloy

3.11 production environment natural occurring produced fluids without contamination from chemicals that will temporarily or continuously reduce the in situ pH Note 1 to entry: Flow back of chemicals for stimulation and scale removal may temporarily reduce the pH significantly and some continuously injected chemicals, such as scale inhibitors, can continuously reduce pH.

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Note 1 to entry: See 6.3 for further information.

ANSI/NACE MR0175/ISO 15156-3:2015(E) 3.12 solid solution single crystalline phase containing two or more elements 3.13 stainless steel steel containing 10.5 % mass fraction or more chromium, possibly with other elements added to secure special properties

4 Symbols and abbreviated terms For the purposes of this document, the symbols and abbreviated terms shown in ANSI/NACE MR0175/ISO 15156-1 and ANSI/NACE MR0175/ISO 15156-2 apply, some of which are repeated for the purpose of convenience, together with the following: AYS

actual yield strength

c-ring

CRA

corrosion-resistant alloy

HBW

Brinell hardness

HRB

Rockwell hardness (scale B)

HRC

Rockwell hardness (scale C)

pCO2

partial pressure of CO2

pH2S

partial pressure of H2S

PWHT

post-weld heat treatment

elemental sulfur

RSRT

rippled strain rate test

SSRT

slow strain rate test

UNS

unified (alloy) numbering system

5 Factors affecting the cracking-resistance of CRAs and other alloys in H2Scontaining environments The cracking behaviour of CRAs and other alloys in H2S-containing environments can be affected by complex interactions of parameters including the following: — chemical composition, strength, heat treatment, microstructure, method of manufacture, and finished condition of the material; — H2S partial pressure or equivalent dissolved concentration in the water phase; — acidity (in situ pH) of the water phase;

— presence of oxygen, sulfur, or other oxidants; — exposure temperature; — pitting resistance of the material in the service environment; — galvanic effects;

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— chloride or other halide ion concentration;

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ANSI/NACE MR0175/ISO 15156-3:2015(E) — total tensile stress (applied plus residual); — exposure time. These factors shall be considered when using this part of ANSI/NACE MR0175/ISO 15156 for the selection of materials suitable for environments containing H2S in oil and gas production systems.

6 Qualification and selection of CRAs and other alloys with respect to SSC, SCC, and GHSC in H2S-containing environments 6.1 General CRAs and other alloys shall be selected for their resistance to SSC, SCC, and/or GHSC as required by the intended service. Compliance of a CRA or other alloy with this part of ANSI/NACE MR0175/ISO 15156 implies cracking resistance within defined environmental service limits. These limits are dependent on the material type or the individual alloy. To enable qualification and/or selection of CRAs and other alloys, the equipment purchaser can be required to provide information on the proposed conditions of exposure to the equipment supplier. In defining the severity of H2S-containing environments, exposures that can occur during system upsets or shutdowns, etc. shall also be considered. Such exposures can include unbuffered, low pH condensed water. The limits given in the tables in Annex A are for production environments and do not cover conditions occurring during injection or flowback of chemicals that can reduce the in situ pH. CRAs and other alloys shall be selected using Annex A or following qualification by successful laboratory testing in accordance with Annex B. Qualification based on satisfactory field experience is also acceptable. Such qualification shall comply with ANSI/NACE MR0175/ISO 15156-1. In Annex A, materials are identified by materials groups. Within each group, alloys are identified by materials type (within compositional limits) or as individual alloys. Acceptable metallurgical conditions and environmental limits are given for which alloys are expected to resist cracking. Environmental limits are given for H2S partial pressure, temperature, chloride concentration, and elemental sulfur. A CRA or other alloy can be qualified by testing for use under operating conditions that are more severe than the environmental limits given in Annex A. Similarly, a CRA or other alloy can be qualified for use in different metallurgical conditions (higher strength, alternative heat treatment, etc.) to those given in Annex A. The documentation of qualifications performed in accordance with Annex B shall meet the requirements in ANSI/NACE MR0175/ISO 15156-1:2015, Clause 9.

6.2 Evaluation of materials properties 6.2.1 Hardness of parent metals If hardness measurements on parent metal are specified, sufficient hardness tests shall be made to establish the actual hardness of the CRA or other alloy being examined. Individual HRC readings exceeding the value permitted by this part of ANSI/NACE MR0175/ISO 15156 may be considered acceptable if the average of several readings taken within close proximity does not exceed the value permitted by this part of ANSI/NACE MR0175/ISO 15156 and no individual reading is greater than 2 HRC above the specified value. Equivalent requirements shall apply to other methods of hardness measurement when specified in this part of ANSI/NACE MR0175/ISO 15156 or referenced in a manufacturing specification.

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The equipment user shall verify qualifications (see B.2.2) and retain documentation supporting the materials selections made.

ANSI/NACE MR0175/ISO 15156-3:2015(E) The conversion of hardness readings to or from other scales is material-dependent. The user may establish the required conversion tables. NOTE The number and location of hardness tests on parent metal are not specified in ANSI/NACE MR0175/ISO 15156 (all parts).

6.2.2 Cracking-resistance properties of welds 6.2.2.1 General The metallurgical changes that occur when welding CRAs and other alloys can affect their susceptibility to SSC, SCC, and/or GHSC. Welded joints can have a greater susceptibility to cracking than the parent material(s) joined. The equipment user may allow the cracking susceptibility of weldments to govern the limits of safe service conditions for a fabricated system. Processes and consumables used in welding should be selected in accordance with good practice and to achieve the required corrosion and cracking resistances. Welding shall be carried out in compliance with appropriate codes and standards as agreed between the supplier and the purchaser. Welding procedure specifications (WPSs) and procedure qualification records (PQRs) shall be available for inspection by the equipment user. Welding PQRs shall include documented evidence demonstrating satisfactory cracking resistance under conditions at least as severe as those of the proposed application. Such evidence shall be based upon one or more of the following: — compliance with the requirements and recommendations for the specific materials group of Annex A (see also 6.2.2.2 and 6.2.2.3); — weld cracking-resistance qualification testing in accordance with Annex B; — documented field experience modelled upon that specified for parent materials in ANSI/NACE MR0175/ISO 15156-1. The requirements and recommendations given in Annex A might not be appropriate for all combinations of parent and weld metals used in the fabrication of equipment and components. The equipment user may require evidence of successful cracking-resistance testing as part of the welding procedure qualification to ensure the weldment produced provides adequate resistance to SSC, SCC, and GHSC for the application. 6.2.2.2 Qualification of welding procedures in accordance with Annex A based upon hardness 6.2.2.2.1 General The qualification of welding procedures for sour service shall, if specified in Annex A, include hardness testing in accordance with 6.2.2.2.2, 6.2.2.2.3 and 6.2.2.2.4. 6.2.2.2.2 Hardness testing methods for welding procedure qualification --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Hardness testing for welding procedure qualification shall be carried out using Vickers HV 10 or HV 5 methods in accordance with ISO 6507-1 or the Rockwell 15N method in accordance with ISO 6508-1. NOTE For the purposes of this part of ANSI/NACE MR0175/ISO 15156, ASTM E384 is equivalent to ISO 6507-1 and ASTM E18 is equivalent to ISO 6508-1.

The use of other methods shall require explicit user approval.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) 6.2.2.2.3 Hardness surveys for welding procedure qualification Hardness surveys for butt welds, fillet welds, repair, and partial penetration welds and overlay welds shall be carried out as described in ANSI/NACE MR0175/ISO 15156-2:2015, 7.3.3.3. 6.2.2.2.4 Hardness acceptance criteria for welds Weld hardness acceptance criteria for CRAs or other alloys given in Annex A shall apply to alloys selected using Annex A. Hardness acceptance criteria can also be established from successful cracking-resistance testing of welded samples. Testing shall be in accordance with Annex B. 6.2.2.3 Qualification of welding procedures in accordance with Annex A by other means of testing Where appropriate, requirements and recommendations to ensure adequate cracking-resistance of welds using other means of testing are provided in the materials groups of Annex A. 6.2.3 Cracking-resistance properties associated with other fabrication methods For CRAs and other alloys that are subject to metallurgical changes caused by fabrication methods other than welding, cracking-resistance qualification testing of the material affected by fabrication shall be specified as part of the qualification of the fabrication process. Qualification testing shall be specified as part of the qualification of burning and cutting processes if any HAZ remains in the final product. The requirements and acceptance criteria of 6.2.2 shall apply to the qualification testing of both fabrication methods and burning/cutting processes subject to the suitable interpretation of the hardness survey requirements of 6.2.2.2.3 for the fabrication method or burning/cutting process. The form and location of the samples used for evaluation and testing shall be acceptable to the equipment user.

6.3 PREN For the purpose of determining conformance with the requirements of this part of ANSI/NACE MR0175/ISO 15156, all FPREN limits specified in this part of ANSI/NACE MR0175/ISO 15156 shall be considered absolute limits as defined in ASTM Practice E29. With the absolute method, an observed value or a calculated value is not to be rounded, but is to be compared directly with the specified limiting value. Conformance or non-conformance with the specification is based on this comparison. The FPREN calculation is based on actual composition, not nominal composition. Nominal composition is used for general classification only. The PREN (FPREN) shall be calculated as given in Formula (1): FPREN  wCr  3,3 w Mo  0,5w W   16w N

(1)

where wCr is the mass fraction of chromium in the alloy, expressed as a percentage mass fraction of the total composition; wMo is the mass fraction of molybdenum in the alloy, expressed as a percentage mass fraction of the total composition; wW is the mass fraction of tungsten in the alloy, expressed as a percentage mass fraction of the total composition; wN

is the mass fraction of nitrogen in the alloy, expressed as a percentage mass fraction of the

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ANSI/NACE MR0175/ISO 15156-3:2015(E) total composition. NOTE There are several variations of the PREN. All were developed to reflect and predict the pitting resistance of Fe/Ni/Cr/Mo CRAs in the presence of dissolved chlorides and oxygen, e.g. in sea water. Though useful, these indices are not directly indicative of corrosion resistance in H2S-containing oil field environments.

7 Purchasing information and marking 7.1 Information that should be supplied for material purchasing 7.1.1 The preparation of material purchasing specifications can require cooperation and exchange of data between the equipment user, the equipment supplier, and the material manufacturer to ensure that the material purchased complies with ANSI/NACE MR0175/ISO 15156-1 and this part of ANSI/NACE MR0175/ISO 15156. 7.1.2

The following information shall be provided:

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— preferred materials types and/or grades (if known); — equipment type (if known); — reference to this part of ANSI/NACE MR0175/ISO 15156; — acceptable bases for selection of materials for cracking-resistance (see Clause 6). 7.1.3 The equipment user and the equipment supplier/material manufacturer may agree that CRAs and other alloys other than those described and or listed in Annex A may be selected subject to suitable qualification testing. If the purchaser intends to make use of such agreements, extensions, and qualifications, the appropriate additional information shall be clearly indicated in the materials purchasing specification. This information includes the following: — requirements for SSC, SCC, and/or GHSC testing (see Clause 6 and Annex B); — service conditions for the specific sour service application. 7.1.4 The information required for material purchasing shall be entered on suitable data sheets. Suggested formats are given in Annex C.

7.2 Marking, labelling, and documentation Materials complying with this part of ANSI/NACE MR0175/ISO 15156 shall be made traceable, preferably by marking, before delivery. Suitable labelling or documentation is also acceptable. For materials qualified and selected for a special application in accordance with Annex B, traceability shall include reference to the environmental conditions of the special application. The equipment user may request the equipment or materials supplier to provide documentation of the materials used in equipment or components and their environmental service limits as defined in this part of ANSI/NACE MR0175/ISO 15156. The tables in Annex C provide designations that can be used.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Annex A (normative) Environmental cracking-resistant CRAs and other alloys (including Table A.1 — Guidance on the use of the materials selection tables)

A.1 General A.1.1 Materials groups The materials groups used to list CRAs or other alloys (see 6.1) are as follows: — austenitic stainless steels (identified as material type and as individual alloys) (see A.2); — highly alloyed austenitic stainless steels (identified as material types and as individual alloys) (see A.3); — solid-solution nickel-based alloys (identified as material types and as individual alloys) (see A.4); — ferritic stainless steels (identified as material type) (see A.5);

— duplex stainless steels (identified as material types) (see A.7); — precipitation-hardened stainless steels (identified as individual alloys) (see A.8); — precipitation-hardened nickel-based alloys (identified as individual alloys) (see A.9); — cobalt-based alloys (identified as individual alloys) (see A.10); — titanium and tantalum (identified as individual alloys) (see A.11); — copper, aluminium (identified as materials types) (see A.12). Subject to A.1.2, A.1.3, A.1.4, and A.1.5 below, the CRAs and other alloys listed in Table A.1 to Table A.42 may be used without further testing for SSC, SCC, and GHSC cracking-resistance within the environmental limits shown. Information on the use of copper and aluminium alloys is contained in A.12. A.13 contains recommendations on the use of cladding, overlays, and wear-resistant alloys. NOTE The materials listed and the restrictions shown are those originally listed in NACE MR0175:2003 (no longer available) except for balloted changes introduced since 2003.

A.1.2 Limits of chemical composition The user of a CRA or other alloy shall ensure that the chemical analysis of the material used meets the material analysis requirements shown for the material in SAE — ASTM, Metals and alloys in the Unified Numbering System. To comply with this part of ANSI/NACE MR0175/ISO 15156, the material shall also meet any provision shown in the text and/or tables of its materials group.

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— martensitic stainless steels (identified as individual alloys) (see A.6);

ANSI/NACE MR0175/ISO 15156-3:2015(E) A.1.3 Environmental and metallurgical limits for cracking-resistance A.2.2 to A.11.2 contain materials selection tables showing the environmental limits of the materials when used for any equipment or component. These subclauses also often contain materials selection tables showing the less restrictive environmental limits of the materials when used for named equipment or components. The tables show the application limits with respect to temperature, pH S, Cl−, pH, S0. These limits apply 2

collectively. The pH used in the tables corresponds to the minimum in situ pH.

NOTE 1 In the tables of this Annex, the SI unit “milligrams per litre” is used for mass concentration. In US Customary units, these are commonly expressed in parts per million (ppm). NOTE 2

Guidance on the calculation of pH S is given in ANSI/NACE MR0175/ISO 15156-2:2015, Annex C. 2

NOTE 3

Guidance on the calculation of pH is given in ANSI/NACE MR0175/ISO 15156-2:2015, Annex D.

NOTE 4 In preparing the materials selection tables, it is assumed that no oxygen is present in the service environment.

Where no specified limit for a variable can be defined in a table, explanatory remarks that reflect current knowledge have been included in the table. The environmental limits for an alloy are valid only within any additional metallurgical limits given for the alloy in the text of the same table. Where tempering of a material is required, the tempering time shall be sufficient to ensure the achievement of the required through-thickness hardness. When purchasing materials, metallurgical properties known to affect the materials' performance in H2Scontaining oil and gas environments in addition to those specifically listed in this Annex should also be considered. ANSI/NACE MR0175/ISO 15156-1:2015, 8.1 lists such properties. A.1.4 Requirements and recommendations on welding The clauses for the materials groups contain requirements and recommendations for welding the materials of the group to achieve satisfactory cracking-resistance in the weldment produced. A.1.5 Other requirements and recommendations on CRAs and other alloys A.1.5.1 Requirements for overlays, surface treatments, plating, coatings, linings, etc. For the composition, cracking-resistance and use of overlays, see A.13. Metallic coatings (electroplated and electroless plated), conversion coatings, plastic coatings, or linings may be used, but are not acceptable for preventing cracking. The effect of their application on the cracking-resistance of the substrate shall be considered. Nitriding with a maximum case depth of 0.15 mm (0.006 in) is an acceptable surface treatment if conducted at a temperature below the lower critical temperature of the alloy being treated. The use of nitriding as a means of preventing cracking in sour service is not acceptable. A.1.5.2 Threading --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Threads produced using a machine-cutting process are acceptable. Threads produced by cold forming (rolling) are acceptable on CRAs and other alloys if the material and the limits of its application otherwise comply with this part of ANSI/NACE MR0175/ISO 15156.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.1.5.3 Cold deformation of surfaces Cold deformation of surfaces is acceptable if caused by processes such as burnishing that do not impart more cold work than that incidental to normal machining operations (such as turning or boring, rolling, threading, drilling, etc.). Cold deformation by controlled shot-peening is acceptable if applied to base materials that comply with this part of ANSI/NACE MR0175/ISO 15156 and if restricted to a maximum shot size of 2.0 mm (0.080 in) and an Almen intensity not exceeding 10C. The process shall be controlled in accordance with SAE AMS2430. A.1.5.4 Identification stamping The use of identification stamping using low-stress (dot, vibratory, and round-V) stamps is acceptable. The use of conventional sharp V-stamping is acceptable in low-stress areas such as the outside diameter of flanges. Conventional sharp V-stamping shall not be performed in high-stress areas unless agreed with the equipment user. A.1.6 Use of materials selection tables Table A.1 provides a guide to the materials selection tables for any equipment or component. It also provides a guide to additional materials selection tables for specific named equipment or components when other, less restrictive, environmental, or metallurgical limits may be applied. NOTE See Note in introduction of this part of ANSI/NACE MR0175/ISO 15156 regarding Annex F of Technical Circular ANSI/NACE MR0175/ISO 15156-3:2009/Cir.2:2013 and Technical Circular ANSI/NACE MR0175/ ISO 15156-3:2009/Cir.3:2014.

A.2 Austenitic stainless steels (identified as material type and as individual alloys) A.2.1 Materials analyses Austenitic stainless steels of this material type shall contain the following elements in the following proportions, expressed as mass fractions: C, 0.08 % max; Cr, 16 % min; Ni, 8 % min; P, 0.045 % max; S, 0.04 % max; Mn, 2.0 % max; and Si, 2.0 % max. Other alloying elements are permitted. Higher carbon contents for UNS S30900 and S31000 are acceptable up to the limits of their respective specifications. The alloys listed in Table D.1 can, but do not necessarily, meet the requirements above. In some cases, more restrictive chemistries are required to comply with the requirements of this materials group. See also A.3.1. It is common industry practice to dual certify 300 series stainless steels as standard grade and low carbon grade such as S31600 (316) and S31603 (316L). The environmental limits given for low carbon 300 series stainless steels are acceptable for the dual certified grades. Free-machining austenitic stainless steel products shall not be used.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

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Table A.1 — Guidance on the use of the materials selection tables of Annex A based on equipment or component type

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.2.2 Environmental and materials limits for the uses of austenitic stainless steels Table A.2 — Environmental and materials limits for austenitic stainless steels used for any equipment or components Materials type/ individual alloy UNS number

Austenitic stainless steel from materials type described in A.2a

S31603b

S20910c

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

60 (140)

100 (15)

See “Remarks” column

60 (140)

Sulfurresistant?

See “Remarks” column

1 000 (145)

50 000

≥4.5

NDSd

90 (194)

1 000 (145)

1 000

≥3.5

NDSd

90 (194)

1 (0.145)

50 000

≥4.5

NDSd

93 (200)

10.2 (1.5)

5 000

≥5.0

NDSd

120 (248)

100 (14.5)

1 000

≥3.5

NDSd

149 (300)

10.2 (1.5)

1 000

≥4.0

NDSd

66 (150)

100 (15)

See “Remarks” column

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Temperature

Partial pressure H2S pH2S

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Remarks

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable. These materials have been used without restrictions on temperature, pH2S, or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

ANSI/NACE MR0175/ISO 15156-3:2015(E) A limit on the martensite content of these austenitic stainless steels should be considered. The stress corrosion cracking resistance of all austenitic stainless steels of the material type described in A.2 can be adversely affected by cold working. These materials shall

—

be in the solution-annealed and quenched or annealed and thermally-stabilized heat-treatment condition,

—

be free of cold work intended to enhance their mechanical properties, and

—

have a maximum hardness of 22 HRC.

UNS S31603 shall be in the solution-annealed and quenched condition when used in environments outside the limits imposed for the material type (i.e. in the top two rows), but within those given specifically for S31603. The following conditions shall apply: b

— the material shall be free from cold work caused by shaping, forming, cold reducing, tension, expansion, etc. after the final solution annealing and quenching treatment; — after the final solution annealing and quenching treatment, hardness and cold work incidental to machining or straightening shall not exceed the limits imposed by the appropriate product specification. UNS S20910 is acceptable for environments inside the limits imposed for the material type and for this alloy, specifically, in the annealed or hot-rolled (hot/cold-worked) condition at a maximum hardness of 35 HRC. c

No data submitted (NDS) to ascertain whether these materials are acceptable in service with presence of elemental sulfur in the environment. d

Table A.3 — Environmental and materials limits for austenitic stainless steels used as valve stems, pins, and shafts Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

Sulfurresistant?

Remarks

S20910

See “Remarks” column

See See See “Remarks” “Remarks” “Remarks” column column column

NDSa

Any combination of temperature, pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

For these applications, the following material restrictions shall also apply: — UNS S20910 at a maximum hardness level of 35 HRC may be used in the cold-worked condition provided this cold working is preceded by solution annealing. No data submitted (NDS) to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.4 — Environmental and materials limits for austenitic stainless steels used in surface applications for control-line tubing, instrument tubing, associated fittings, and screen devices

S31600

Temperature

Partial pressure H 2S pH2S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfur resistant?

See “Remarks” column

NDSa

Remarks

This material has been used for these components without restriction on − temperature, pH2S, Cl , or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

UNS S31600 stainless steel may be used for compression fittings and instrument tubing even though it might not satisfy the requirements stated for any equipment or component in Table A.2. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

Table A.5 — Environmental and materials limits for austenitic stainless steels used as seal rings and gaskets Individual alloy UNS number

J92600, J92900 S30400, S30403 S31600, S31603

Temperature

Partial pressure H 2S pH2S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

NDSa

Remarks

Any combination of temperature, pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

For these applications, the following materials restrictions shall apply; — J92600, J92900 API compression seal rings and gaskets made of centrifugally cast material in the as-cast or solution-annealed condition shall have a hardness of 160 HBW (83 HRB) maximum; — S30400, S30403, S31600 or S31603 API compression seal rings and gaskets made of wrought material in the solutionannealed condition shall have a hardness of 160 HBW (83 HRB) maximum. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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Individual alloy UNS number

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.6 — Environmental and materials limits for austenitic stainless steels used in compressors and instrumentation and control devices Materials type

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Remarks

See “Remarks” column

NDSa

Any combination of temperature, pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

See “Remarks” column

NDSa

These materials have been used for these components without restriction on − temperature, pH2S, Cl , or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

Compressors Austenitic stainless steel from materials type described in A.2

Instrumentation and control devicesb Austenitic stainless steel from materials type described in A.2

See “Remarks” column

For these applications, these materials shall also —

be in the solution-annealed and quenched or annealed and stabilized heat-treatment condition,

—

be free of cold work intended to enhance their mechanical properties, and

—

have a maximum hardness of 22 HRC.

A limit on the martensite content of these austenitic stainless steels should be considered. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

Instrumentation and control devices include, but are not limited to diaphragms, pressure measuring devices, and pressure seals. b

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.7 — Environmental and materials limits for austenitic stainless steels used in gas lift service and for special components for subsurface applications such as downhole screens, controlline tubing, hardware (e.g. set screws, etc.), injection tubing, and injection equipment Materials type

Austenitic stainless steel from materials group described in A.2

Temperature

Partial pressure H2S pH2S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See See See “Remarks” “Remarks” “Remarks” column column column

NDSa

Remarks

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

A.2.3 Welding of austenitic stainless steels of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable. Weldments may be repair-welded if they meet the welding procedure requirements.

A.3 Highly alloyed austenitic stainless steels (identified as material types and as individual alloys) A.3.1 Materials chemical compositions Table D.2 lists the chemical compositions of some alloys of this type that can meet the analysis-related requirements shown in the text of Table A.8 and Table A.9. However, in some cases, this requires production within more restricted ranges of chemical analysis than those specified in Table D.2. Austenitic stainless steels included in Table D.2 that do not meet the restricted ranges of chemical analysis required in Table A.8 and Table A.9, but meet the requirements of A.2.1 may be considered as part of materials group A.2. Free-machining highly alloyed austenitic stainless steels shall not be used.

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Austenitic stainless steel, “L,” filler metal shall have a maximum carbon content of 0.03 % mass fraction.

ANSI/NACE MR0175/ISO 15156-3:2015(E) A.3.2 Environmental and materials limits for the uses of highly alloyed austenitic stainless steels Table A.8 — Environmental and materials limits for highly alloyed austenitic stainless steels used for any equipment or components Materials type/ individual alloy UNS number

Materials type 3a, 3b, and J93254

Materials type 3b

N08926

J95370

Temperature

Partial pressure H2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

60 (140)

100 (15)

See “Remarks” column

Remarks

See “Remarks” column

Any combinations of chloride concentration, and in situ pH occurring in production environments are acceptable.

See “Remarks” column

These materials have been used without restrictions on temperature, pH2S, or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

121 (250)

700 (100)

5 000

See “Remarks” column

The in situ pH values occurring in production environments are acceptable.

149 (300)

310 (45)

5 000

See “Remarks” column

171 (340)

100 (15)

5 000

See “Remarks” column

121 (250)

700 (100)

65 000

≥3.5; See also “Remarks” column

See “Remarks” column

150 (302)

700

101 000

pH estimated from laboratory test conditions. UNS N08926 is material type 3b tested to higher limits of chloride concentration than apply for the materials type as a whole. The in situ pH values occurring in production environments are acceptable.

These materials shall also comply with the following: — materials type 3a shall be highly alloyed austenitic stainless steel with (wNi + 2wMo) > 30 (where wMo has a minimum value of 2 %). The symbol w represents the percentage mass fraction of the element indicated by the subscript; —

materials type 3b shall be highly alloyed austenitic stainless steel with FPREN > 40.0;

—

materials types 3a and 3b (including N08926) shall be in the solution-annealed condition;

— UNS J93254 (CK3McuN, cast 254SMO) in accordance with ASTM A351, ASTM A743, or ASTM A744 shall be in the cast, solution heat-treated and water-quenched condition, and shall have a maximum hardness of 100 HRB; — UNS J95370 shall be in the solution heat-treated and water-quenched condition and shall have a maximum hardness of 94 HRB.

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.9 — Environmental and materials limits for highly alloyed austenitic stainless steels used for downhole tubular components and packers and other subsurface equipment Materials type/ individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

Materials type 3a and 3b

60 (140)

100 (15)

Materials type 3a

60 (140)

Materials type 3b

Remarks

See “Remarks” column

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

350 (50)

See “Remarks” column

121 (250)

700 (100)

5 000

See “Remarks” column

The in situ pH values occurring in production environments are acceptable.

149 (300)

310 (45)

5 000

See “Remarks” column

171 (340)

100 (15)

5 000

See “Remarks” column

121 (250)

700 (100)

65 000

≥3,5; See also “Remarks” column

pH is estimated from laboratory test conditions. UNS N08926 is material type 3b tested to higher limits of chloride concentration than apply for the materials type as a whole.

For these applications, these materials shall also comply with the following: — highly alloyed austenitic stainless steels used for downhole tubular components shall contain at least these elements, expressed as percentage mass fractions: C, 0.08 % max; Cr, 16 % min; Ni, 8 % min; P, 0.03 % max; S, 0.030 % max; Mn, 2 % max; and Si, 0.5 % max. Other alloying elements may be added; — materials type 3a shall be highly alloyed austenitic stainless steel with (wNi + 2wMo) > 30 (where wMo has a minimum value of 2 %); —

materials type 3b shall be highly alloyed austenitic stainless steel with a FPREN > 40.0.

All the above alloys shall be in the solution-annealed and cold-worked condition with a maximum hardness of 35 HRC.

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--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

N08926

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.10 — Environmental and materials limits for highly alloyed austenitic stainless steels used in gas lift service Materials type

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See “Remarks” column

NDSa

Remarks

Highly alloyed austenitic stainless steel from materials group described in A.3

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

Table A.11 — Environmental and materials limits for highly alloyed austenitic stainless steels used as instrument tubing, control-line tubing, compression fittings, and surface and downhole screen devices Individual alloy Temperature UNS number

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

Materials types 3a and 3b

See “Remarks” column

N08904

See “Remarks” column

Remarks

See “Remarks” column

NDSa

See “Remarks” column

NDSa

Any combination of temperature, pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Materials type 3a shall be highly alloyed austenitic stainless steel with (wNi + 2wMo) > 30 (where wMo has a minimum value of 2 % mass fraction). The symbol w represents the percentage mass fraction of the element indicated by the subscript. Materials type 3b shall be highly alloyed austenitic stainless steel with a FPREN > 40.0. Wrought N08904 for use as instrument tubing shall be in the annealed condition with a maximum hardness of 180 HV10. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

A.3.3 Welding highly alloyed austenitic stainless steels of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable. Weldments may be repair-welded if they meet the weld procedure requirements.

A.4 Solid-solution nickel-based alloys (identified as material types and as individual alloys) A.4.1 Materials chemical compositions Table A.12 provides a breakdown of this materials group into types 4a, 4b, 4c, 4d, and 4e used in Table A.13 and Table A.14. Table D.4 contains the chemical compositions of some copper-nickel alloys of this group. Table A.12 — Materials types of solid-solution nickel-based alloys Materials type

Ni + Co mass fraction

Mo mass fraction

Mo + W mass fraction

min

Type 4a

19.0

29.5

2.5

—

Solution-annealed or annealed

Type 4b

14.5

—

Solution-annealed or annealed

Type 4c

19.5

29.5

2.5

—

Solution-annealed or annealed and cold-worked

Type 4d

19.0

—

Solution-annealed or annealed and cold-worked

Type 4e

14.5

—

Solution-annealed or annealed and cold-worked

Type 4fa

20.0

15.5

—

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Cr mass fraction

Metallurgical condition

a) Solution-annealed or annealed and cold-worked condition b) Solution-annealed or annealed and cold-worked and aged condition

Table D.3 lists the chemical compositions of some alloys that can, but do not necessarily, meet the restrictions of one or more of these types. In some cases, more restrictive compositions than those shown in Table D.3 may be needed. a

The type 4f family is currently limited to only UNS N07022.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.4.2 Environmental and materials limits for the uses of solid-solution nickel-based alloys Table A.13 — Environmental and materials limits for solid-solution nickel-based alloys used in any equipment or component Materials type/ individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

Remarks

max

°C (°F)

kPa (psi)

mg/l

Annealed alloys of types 4a and 4b

See “Remarks” column

Yes

See “Remarks” column

NDSa

These materials have been used without restriction on temperature, pH2S, chloride concentration, or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

N04400 N04405

See “Remarks” column

Wrought or cast solid-solution nickel-based products made from alloys of types 4a and 4b shall be in the solution-annealed or annealed condition. UNS N04400 and UNS N04405 shall have a maximum hardness of 35 HRC. Wellhead and christmas tree components shall also be in accordance with ISO 10423. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.14 — Environmental and materials limits for annealed and cold-worked, solid-solution nickel-based alloys used as any equipment or componenta Materials type

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

232 (450)

200 (30)

See “Remarks” column

218 (425)

700 (100)

See “Remarks” column

204 (400)

1 000 (150)

See “Remarks” column

177 (350)

1 400 (200)

See “Remarks” column

132 (270)

See “Remarks” column

218 (425)

2 000 (300)

See “Remarks” column

149 (300)

See “Remarks” column

232 (450)

7 000 (1 000)

See “Remarks” column

204 (400)

See “Remarks” column

180 000

See “Remarks” column

Remarks

Coldworked alloys of types 4d and 4e

Coldworked alloys of type 4e

Coldworked alloys of type 4f

204 (400)

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3 500 (500)

Yes

Any combination of hydrogen sulfide, chloride concentration, and in situ pH in production environments is acceptable.

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

Yes

Any combinations of hydrogen sulfide, chloride concentration, and in situ pH in production environments are acceptable.

Yes

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

Yes

Any combination of hydrogen sulfide, chloride concentration, and in situ pH in production environments is acceptable.

Yes

Any in situ production environment pH is acceptable for pCO + pH S ≤ 7 000 kpa 2 2 (1 000 psi)

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Coldworked alloys of types 4c, 4d and 4e

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

ANSI/NACE MR0175/ISO 15156-3:2015(E) Any in situ production environment pH is acceptable for pCO such that: 2

288 (550)

7 000 (1000)

180 000

See “Remarks” column

NDSb

For pH S < 3 000 kPa (450 psi): 2 pCO + pH S ≤ 10 000 kPa 2

(1 450 psi). For pH S from 3 000 kPa to 2

7 000 kPa: pCO ≤ 7 000 kPa (1 000 psi). 2 Wrought or cast solid-solution nickel-based products in these applications shall be in the annealed and cold-worked condition or annealed, cold-worked, and aged for type 4f and shall meet all of the following as applicable: 1)

the maximum hardness value for types 4c, 4d, and 4e in these applications shall be 40 HRC;

the maximum yield strength of the alloys achieved by cold work shall be

—

type 4c: 1 034 MPa (150 ksi);

—

type 4d: 1 034 MPa (150 ksi);

—

type 4e: 1 240 MPa (180 ksi).

UNS N10276 (Type 4e) when used at a minimum temperature of 121 °C (250 °F) shall have a maximum hardness of 45 HRC;

4) UNS N07022 (Type 4f) in the annealed and cold-worked condition shall have a maximum hardness of 43 HRC and a maximum yield strength of 1 413 MPa (205 ksi); 5) UNS N07022 (Type 4f) in the annealed and cold-worked and aged condition shall have a maximum hardness of 47 HRC and a maximum yield strength of 1 420 MPa (206 ksi). a

The limits of application of the materials types 4c, 4d, and 4e in this table overlap.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. b

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.15 — Environmental and materials limits for nickel-based alloys used for bearing pins Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

Remarks

See “Remarks” column

NDSa

Any combination of temperature, pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

N10276

N10276 bearing pins, e.g. core roll pins, shall be in the cold-worked condition with a maximum hardness of 45 HRC. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

Table A.16 —Environmental and materials limits for nickel-based alloys used in gas lift service and for downhole running, setting, and service tool applications for temporary service Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

Temperature Individual alloy UNS number

Sulfurresistant?

Remarks

These materials have been used for these components without restriction on

N04400 N04405

See “Remarks” column

NDSa

− temperature, pH2S, Cl , or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

A.4.3 Welding solid-solution nickel-based alloys of this materials group --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable. There are no hardness requirements for welding solid-solution nickel-based alloys with solid-solution nickel-based weld metal.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

A.5 Ferritic stainless steels (identified as material type) A.5.1 Materials chemical compositions Table D.5 lists the chemical compositions of some alloys of this type. A.5.2 Environmental and materials limits for the uses of ferritic stainless steels Table A.17 — Environmental and materials limits for ferritic stainless steels used for any equipment or components Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

Temperature Materials type

Ferritic stainless steels from materials type described in A.5

Sulfurresistant?

Remarks

See “Remarks” column

10 (1.5)

See “Remarks” column

≥3.5

NDSa

Subject to limitations on pH2S and pH. These materials have been used without restrictions on temperature or chloride concentration in production environments. No limits on these two parameters are set, but some combinations of their values might not be acceptable.

These materials shall be in the annealed condition and shall have a maximum hardness of 22 HRC. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

A.5.3 Welding of ferritic stainless steels of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). Hardness testing of qualification welds shall be carried out and the maximum hardness shall be 250 HV or, if a different hardness test method is permitted, its equivalent.

A.6 Martensitic (stainless) steels (identified as individual alloys) A.6.1 Materials chemical compositions --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Table D.6 lists the chemical compositions of the martensitic steel alloys shown in Table A.18 to Table A.23. Free-machining martensitic stainless steels shall not be used.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.6.2 Environmental and materials limits for the uses of martensitic stainless steels Table A.18 — Environmental and materials limits for martensitic stainless steels used for any equipment or components Individual alloy Temperature UNS number

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

S41000 S41500 S42000 J91150 J91151 J91540 S42400

See “Remarks” column

10 (1.5)

See “Remarks” column

≥3.5

NDSa

S41425

See “Remarks” column

10 (1.5)

See “Remarks” column

≥3.5

Remarks

Any combination of temperature and chloride concentration occurring in production environments is acceptable

These materials shall also comply with the following: a) cast or wrought alloys UNS S41000, J91150 (CA15), and J91151 (CA15M) shall have a maximum hardness of 22 HRC and shall be 1)

austenitized and quenched or air-cooled;

tempered at 621 °C (1 150 °F) minimum, then cooled to ambient temperature;

3) tempered at 621 °C (1 150 °F) minimum, but lower than the first tempering temperature, then cooled to ambient temperature. b) low-carbon, martensitic stainless steels, either cast J91540 (CA6NM), or wrought S42400 or S41500 (F6NM) shall have a maximum hardness of 23 HRC and shall be 1)

austenitized at 1 010 °C (1 850 °F) minimum, then air- or oil-quenched to ambient temperature;

tempered at 649 °C to 691 °C (1 200 °F to 1 275 °F), then air-cooled to ambient temperature;

tempered at 593 °C to 621 °C (1 100 °F to 1 150 °F), then air-cooled to ambient temperature.

c) cast or wrought alloy UNS S42000 shall have a maximum hardness of 22 HRC and shall be in the quenched and tempered heat-treatment condition; d) wrought low-carbon UNS S41425 martensitic stainless steel in the austenitized, quenched, and tempered condition shall have a maximum hardness of 28 HRC. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.19 — Environmental and materials limits for martensitic stainless steels used as downhole tubular components and for packers and other subsurface equipment Specification/ Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

ISO 11960 L-80 Type 13 Cr, S41426, S42500

See “Remarks” column

10 (1.5)

See “Remarks” column

≥3.5

NDSa

S41429

See “Remarks” column

10 (1.5)

See “Remarks” column

≥4.5

NDSa

Remarks

Any combination of temperature and chloride concentration occurring in production environments is acceptable

For these applications, these materials shall also comply with the following: a) UNS S41426 tubular components shall be quenched and tempered to maximum 27 HRC and maximum yield strength 724 MPa (105 ksi); b) UNS S42500 (15 Cr) tubing and casing is acceptable as Grade 80 [SMYS 556 MPa (80 ksi)] only and shall be in the quenched and double-tempered condition with a maximum hardness of 22 HRC. The quench and double-temper process shall be as follows: 1)

austenitize at minimum 900 °C (1 652 °F), then air- or oil-quench;

temper at minimum 730 °C (1 346 °F), then cool to ambient temperature;

temper at minimum 620 °C (1 148 °F), then cool to ambient temperature. --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

c) UNS S41429 tubular components shall be quenched and tempered or normalized and tempered to a maximum hardness of 27 HRC and a maximum yield strength of 827 MPa (120 ksi). No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

Table A.20 — Environmental and materials limits for martensitic alloy steel used as subsurface equipment Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

Sulfurresistant?

Remarks

See “Remarks” column

NDSa

These materials have been used without restrictions on temperature, pH2S, chloride concentration, or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

K90941

See “Remarks” See column “Remarks ” column

See “Remarks” column

For these applications, UNS K90941 (martensitic 9Cr 1Mo to ASTM A276 type 9, ASTM A182/A182M grade F9 or ASTM A213/A213M grade T9) shall have a maximum hardness of 22 HRC. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.21 — Environmental and materials limits for martensitic stainless steels used as packers and subsurface equipment Alloy specification

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

AISI 420 (modified)

See “Remarks” column

10 (1.5)

S41427

See “Remarks” column

10 (1.5)

Remarks

See “Remarks” column

≥3.5

NDSa

Any combination of temperature and chloride concentration occurring in production environments is acceptable

6 100

≥3.5

NDSa

Temperatures occurring in production environments are acceptable.

For these applications, AISI 420 (modified) shall have chemical composition in accordance with ISO 11960 L-80 Type 13 Cr and shall be quenched and tempered to 22 HRC maximum. UNS S41427 shall have a maximum hardness of 29 HRC and shall have been heat-treated in accordance with the following threestep process: a)

austenitize at 900 °C to 980 °C (1 652 °F to 1 796 °F), then air-cool or oil-quench to ambient temperature;

tempered at 600 °C to 700 °C (1 112 °F to 1 292 °F), then air-cool to ambient temperature;

tempered at 540 °C to 620 °C (1 004 °F to 1 148 °F), then air-cool to ambient temperature.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.22 — Environmental and materials limits for martensitic stainless steels used as compressor components Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See “Remarks” column

NDSa

Remarks

S41000 S41500 S42400 J91150 J91151 J91540

Any combination of temperature, pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

For these applications, these materials shall also comply with the following: --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

a) cast or wrought alloys UNS S41000, J91150 (CA15), and J91151 (CA15M) shall have 22 HRC maximum hardness if used for compressor components and shall be 1)

austenitized and quenched or air-cooled;

tempered at 621 °C (1 150 °F) minimum, then cooled to ambient temperature;

3) tempered at 621 °C (1 150 °F) minimum, but lower than the first tempering temperature, then cooled to ambient temperature. b) low-carbon, martensitic stainless steels, either cast J91540 (CA6NM) or wrought S42400 or S41500 (F6NM), shall have a maximum hardness of 23 HRC and shall be 1)

austenitized at 1 010 °C (1 850 °F) minimum, then air- or oil-quenched to ambient temperature;

tempered at 649 °C to 690 °C (1 200 °F to 1 275 °F), then air-cooled to ambient temperature;

tempered at 593 °C to 621 °C (1 100 °F to 1 150 °F), then air-cooled to ambient temperature.

c) if used for impellers, cast or wrought alloys UNS S41000, J91150 (CA15) and J91151 (CA15M), cast J91540 (CA6NM) and wrought S42400, or S41500 (F6NM) shall exhibit a threshold stress ≥95 % of actual yield strength in the anticipated service environment. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.23 — Environmental and materials limits for martensitic stainless steels used as wellhead and tree components and valve and choke components (excluding casing and tubing hangers and valve stems) Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max.

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

≥3.5

NDSa

Remarks

S41000 S41500 S42000 J91150 J91151 J91540 S42400

Subject to limitations on in situ pH, these materials have been used for these components without restriction on temperature, pH2S, or Cl− in production environments. No limits on these parameters are set, but some combinations of their values might not be acceptable.

For these applications, these materials shall also comply with the following: a)

cast or wrought alloys UNS S41000, J91150 (CA15), and J91151 (CA15M), shall have 22 HRC maximum hardness and shall be 1)

austenitized and quenched or air-cooled;

tempered at 620 °C (1 150 °F) minimum, then cooled to ambient temperature;

3) tempered at 620 °C (1 150 °F) minimum, but lower than the first tempering temperature, then cooled to ambient temperature. b) low-carbon, martensitic stainless steels either cast J91540 (CA6NM) or wrought S42400 or S41500 (F6NM) shall have 23 HRC maximum hardness and shall be 1)

austenitized at 1 010 °C (1 850 °F) minimum, then air- or oil-quenched to ambient temperature;

tempered at 648 °C to 690 °C (1 200 °F to 1 275 °F), then air-cooled to ambient temperature;

tempered at 593 °C to 620 °C (1 100 °F to 1 150 °F), then air-cooled to ambient temperature.

c) cast or wrought alloy UNS S42000 shall have a maximum hardness of 22 HRC and shall be in the quenched and tempered heat-treatment condition. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.6.3 Welding of martensitic stainless steels of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable. Martensitic stainless steels welded with nominally matching consumables shall meet the following requirements. Weldments in martensitic stainless steels shall undergo a PWHT at 621 °C (1 150 °F) minimum and shall comply with 6.2.2.2. Weldments in the low-carbon martensitic stainless steels [cast J91540 (CA6NM) or wrought S42400 or S41500 (F6NM)] shall undergo a single- or double-cycle PWHT after first being cooled to 25 °C (77 °F), as follows: — single-cycle PWHT shall be at 580 °C to 621 °C (1 075 °F to 1 150 °F); — double-cycle PWHT shall be at 671 °C to 691 °C (1 240 °F to 1 275 °F), then cooled to 25 °C (77 °F) or less, then heated to 580 °C to 621 °C (1 075 °F to 1 150 °F).

A.7 Duplex stainless steels (identified as material types) A.7.1 Materials chemical compositions Table D.7 lists the chemical compositions of some duplex stainless steel alloys that can, but do not necessarily, meet the restrictions of this materials group. In some cases, more restrictive chemistries than those shown in Table D.7 are needed.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.7.2 Environmental and materials limits for the uses of duplex stainless steels Table A.24 — Environmental and materials limits for duplex stainless steels used for any equipment or component Materials type/ individual alloy UNS number

Temperature

Partial pressure H2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

30 ≤ FPREN ≤ 40.0 Mo ≥ 1.5 %

232 (450)

10 (1.5)

See “Remarks” column

NDSa

S31803 (HIP)

232 (450)

10 (1.5)

See “Remarks” column

40.0 < FPREN ≤ 45

232 (450)

20 (3)

See “Remarks” column

NDSa

30 ≤ FPREN ≤ 40.0 Mo ≥ 1.5 %

See “Remarks” column

NDSa

40.0 < FPREN ≤ 45

See “Remarks” column

Remarks

See “Remarks” column

NDSa

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable

These materials have been used without restrictions on temperature, pH2S or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

Wrought and cast duplex stainless steels shall —

be solution-annealed and liquid-quenched or rapidly cooled by other methodsb,

—

have a ferrite content (volume fraction) of between 35 % and 65 %, and

—

not have undergone ageing heat-treatments.

Hot isostatic pressure-produced (HIP)[15] duplex stainless steel UNS S31803 (30 ≤ FPREN ≤ 40.0 Mo ≥ 1.5 %) shall have a maximum hardness of 25 HRC and shall —

be in the solution-annealed and water-quenched condition,

—

have a ferrite content (volume fraction) of between 35 % and 65 %, and

—

not have undergone ageing heat-treatments.

NOTE Higher values of FPREN provide higher corrosion resistance; however, they also lead to increased risk of sigma- and alphaprime phase formation in the materials' ferrite phase during manufacture depending on product thickness and achievable quench rate. The ranges of FPREN quoted are typical of those found to minimize the problem of sigma- and alpha-prime phase formation. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

A rapid cooling rate is one sufficiently fast to avoid the formation of deleterious phases such as sigma-phase and precipitates. The presence of deleterious phases can reduce the cracking-resistance of duplex stainless steels. --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.25 — Environmental and materials limits for duplex stainless steels used as downhole tubular components and as packers and other subsurface equipment Materials type

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

Sulfurresistant?

Remarks

30 ≤ FPREN ≤ 40.0 Mo ≥ 1.5 %

40.0 < FPREN ≤ 45

See “Remarks” column

2 (0.3)

20 (3)

See “Remarks” column

120 000

See “Remarks” column

NDSa

Any combination of temperature, chloride concentration and in situ pH occurring in production environments is acceptable.

NDSa

Any combination of temperature and in situ pH occurring in production environments is acceptable. Chloride limits have been found to be strongly dependent upon yield strength and the level of cold work.

For these applications, these materials shall —

be in the solution-annealed, liquid-quenched, and cold-worked condition,

—

have a ferrite content (volume fraction) of between 35 % and 65 %, and

—

have a maximum hardness of 36 HRC.

A.7.3 Welding of duplex stainless steels of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable. A cross-section of the weld metal, HAZ, and base metal shall be examined as part of the welding procedure qualification. The microstructure shall be suitably etched and examined at ×400 magnification and shall have grain boundaries with no continuous precipitates. Intermetallic phases, nitrides, and carbides shall not exceed 1.0 % in total. The sigma phase shall not exceed 0.5 %. The ferrite content in the weld metal root and unreheated weld cap shall be determined in accordance with ASTM E562 and shall be in the range of 30 % to 70 % volume fraction.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

A.8 Precipitation-hardened stainless steels (identified as individual alloys) A.8.1 Materials chemical compositions Table D.8 lists the chemical compositions of the precipitation-hardened stainless steels shown in the tables of A.8.2. Austenitic precipitation-hardened stainless steels are addressed in Table A.26. Martensitic precipitation-hardened stainless steels are addressed in Table A.27 to Table A.30. A.8.2 Environmental and materials limits for the uses of precipitation-hardened stainless steels Table A.26 — Environmental and materials limits for austenitic precipitation-hardened stainless steels used for any equipment or component Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

Sulfurresistant?

Remarks

S66286

65 (150)

100 (15)

See “Remarks” column

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

UNS S66286 shall have a maximum hardness of 35 HRC and shall be in either the solution-annealed and aged or solution-annealed and double-aged condition.

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Individual alloy UNS number

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.27 — Environmental and materials limits for martensitic precipitation-hardened stainless steels used for wellhead and christmas tree components (excluding bodies and bonnets), valves and chokes (excluding bodies and bonnets), and packers and other subsurface equipment Individual alloy Temperature UNS number

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

UNS S17400

See “Remarks” column

3.4 (0.5)

See “Remarks” column

≥4.5

NDSa

UNS S45000

See “Remarks” column

10 (1.5)

See “Remarks” column

≥3.5

NDSa

Remarks

Any combination of temperature and chloride concentration occurring in production environments is acceptable.

For these applications, these materials shall also comply with the following: a) wrought UNS S17400 precipitation-hardening martensitic stainless steels shall have a maximum hardness of 33 HRC and shall have been heat-treated in accordance with either 1) or 2), as follows: 1)

double age-hardening process at 620 °C (1 150 °F): —

solution-anneal at (1 040 ± 14) °C [(1 900 ± 25) °F] and air-cool or liquid-quench to below 32 °C (90 °F);

— first precipitation-hardening cycle at (620 ± 14) °C [(1 150 ± 25) °F] for 4 h minimum at temperature, then air-cool or liquid-quench to below 32 °C (90 °F); — second precipitation-hardening cycle at (620 ± 14) °C [(1 150 ± 25) °F] for 4 h minimum at temperature, then air-cool or liquid-quench to below 32 °C (90 °F). 2)

modified double age-hardening process: —

solution-anneal at (1 040 ± 14) °C [(1 900 ± 25) °F], then air-cool or liquid-quench to below 32 °C (90 °F);

— first precipitation-hardening cycle at (760 ± 14) °C [(1 400 ± 25) °F] for 2 h minimum at temperature and air-cool or liquid-quench to below 32 °C (90 °F); — second precipitation-hardening cycle at (620 ± 14) °C [(1 150 ± 25) °F] for 4 h minimum at temperature, then air-cool or liquid-quench to below 32 °C (90 °F). b) wrought UNS S45000 molybdenum-modified martensitic precipitation-hardened stainless steel shall have a maximum hardness of 31 HRC (equivalent to 306 HBW for this alloy) and shall have undergone the following two-step heat-treatment procedure: 1)

solution-anneal;

precipitation-harden at (620 ± 8) °C [(1 150 ± 15) °F] for 4 h minimum at temperature.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.28 — Environmental and materials limits for martensitic precipitation-hardened stainless steels used as non-pressure-containing internal-valve, pressure-regulator, and level-controller components and miscellaneous equipment Individual alloy UNS number

Temperature

Partial pressure H2S pH S

Chloride conc.

max kPa (psi)

max mg/l

Sulfurresistant?

Remarks

max °C (°F)

Non-pressure-containing internal-valve, pressure-regulator, and level-controller components CB7Cu-1 CB7Cu-2

See “Remarks” column

NDSa

These materials have been used for these components without restriction − on temperature, pH2S, Cl , or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

S17400 S15500

See “Remarks” column

NDSa

S45000

See “Remarks” column

NDSa

Any combination of temperature. − pH2S, Cl , and in situ pH occurring in production environments is acceptable.

See “Remarks” column

NDSa

This alloy has been used in service tool applications at the surface and for temporary drilling and subsurface well- servicing equipment when stressed at less than 60 % of its specified minimum yield strength under working conditions. Environmental limits for this alloy for these applications have not been established.

Miscellaneous equipment S17400

See “Remarks” column

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ANSI/NACE MR0175/ISO 15156-3:2015(E) For these applications, these materials shall also comply with the following: a) cast CB7Cu-1 and CB7Cu-2 shall be in the H1150 DBL condition in accordance with ASTM A747/A747M and shall have a maximum hardness of 30 HRC; b) wrought UNS S17400 and S15500 precipitation-hardening martensitic stainless steels shall have a maximum hardness of 33 HRC and shall have been heat-treated in accordance with either 1) or 2), as follows: 1)

double age-hardening process at 620°C (1 150°F): —

solution-anneal at (1 040 ± 14) °C [(1 900 ± 25) °F], then air-cool or liquid-quench to below 32 °C (90 °F);

— first precipitation-hardening cycle at (620 ± 14) °C [(1 150 ± 25) °F] for 4 h minimum at temperature and air-cool or liquid-quench to below 32 °C (90 °F); — second precipitation-hardening cycle at (620 ± 14) °C [(1 150 ± 25) °F] for 4 h minimum at temperature and air-cool or liquid-quench to below 32 °C (90 °F). 2)

modified double age-hardening process: —

solution-anneal at (1 040 ± 14) °C [(1 900 ± 25) °F] and air-cool or liquid-quench to below 32 °C (90 °F);

for UNS S17400, limits on its ferrite content should be considered;

d) wrought UNS S45000 precipitation-hardening martensitic stainless steel shall have a maximum hardness of 31 HRC (equivalent to 306 HBW for this alloy) and shall be heat-treated using the following two-step process: 1)

solution-anneal;

precipitation-harden at (621 ± 8) °C [(1 150 ± 14) °F] for 4 h minimum at temperature.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment.

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.29 — Environmental and materials limits for martensitic precipitation-hardened stainless steels used as snap rings Individual alloy Temperature UNS number

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

Remarks

S15700

See See “Remarks” “Remarks” column column

NDSa

Any combination of

− temperature. pH2S, Cl , and in situ pH occurring in production environments is acceptable.

For this application, UNS S15700 snap rings originally in the RH950 solution-annealed and aged condition shall also be further heattreated to a hardness of between 30 HRC and 32 HRC using the following three-step process: a)

temper at 620 °C (1 150 °F) for 4 h, 15 min, then cool to room temperature in still air;

re-temper at 620 °C (1 150 °F) for 4 h, 15 min, then cool to room temperature in still air;

temper at 560 °C (1 050 °F) for 4 h, 15 min, then cool to room temperature in still air.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.30 — Environmental and materials limits for martensitic precipitation-hardened stainless steels used in compressor components Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

S17400 S15500

See “Remarks” column

NDSa

S45000

See “Remarks” column

NDSa

Remarks

Any combination of − temperature. pH2S, Cl , and in situ pH occurring in production environments is acceptable. Any combination of − temperature. pH2S, Cl , and in situ pH occurring in production environments is acceptable.

For these applications, these materials shall also comply with the following: a) wrought UNS S17400 and S15500 precipitation-hardening martensitic stainless steels shall have a maximum hardness of 33 HRC and shall have been heat-treated in accordance with either 1) or 2), as follows: 1)

double age-hardening process at 620 °C (1 150 °F): — solution-anneal at (1 040 ± 14) °C [(1 900 ± 25) °F] and air-cool or liquid-quench to below 32 °C (90 °F);

modified double age-hardening process: —

solution-anneal at (1 040 ± 14) °C [(1 900 ± 25) °F] and air-cool or liquid-quench to below 32 °C (90 °F);

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

for UNS S17400, limits on its ferrite content should be considered;

c) for use as impellers at higher hardness (strength) levels, these alloys shall be tested in accordance with Annex B at a test stress level of at least 95 % of AYS; d) wrought UNS S45000 molybdenum-modified martensitic precipitation-hardened stainless steel shall have a maximum hardness of 31 HRC (equivalent to 306 HBW for this alloy) and shall have undergone the following two-step heat-treatment procedure: 1)

solution annealing;

precipitation hardening at (620 ± 8) °C [1 150 ± 15) °F] for 4 h minimum at temperature.

e) UNS S17400 or S15500 used for impellers at a hardness of >33 HRC shall exhibit a threshold stress ≥95 % of AYS in the anticipated service environment (see B.3.4). No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.8.3 Welding of precipitation-hardened stainless steels of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2).

A.9 Precipitation-hardened nickel-based alloys (identified as individual alloys) A.9.1 Materials chemical compositions Table D.9 lists the chemical compositions of the precipitation-hardened nickel-based alloys shown in Table A.31 to Table A.37. A.9.2 Environmental and materials limits for the uses of precipitation-hardened nickel-based alloys Table A.31 to Table A.33 give the environmental and materials limits for the uses for any equipment or component of precipitation-hardened nickel-based alloys divided into groups I, II, and III, respectively.

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The hardness of the base metal after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective metal for the weld alloy.

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.31 — Environmental and materials limits for precipitation-hardened nickel-based alloys (I) used for any equipment or component Individual alloy UNS number

Temperature

Partial pressure H2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

232 (450)

200 (30)

See “Remarks” column

204 (400)

1 400 (200)

See “Remarks” column

149 (300)

2 700 (400)

See “Remarks” column

135 (275)

See “Remarks” column

Yes

135 (275)

See “Remarks” column

NDSa

135 (275)

See “Remarks” column

NDSa

175 (347)

3 500 (500)

139 000

≥3.5, See also “Remarks” column

Remarks

N07031 N07048 N07773 N09777 (wrought) N07718 (cast) N09925 (cast)

N07031 N07048 N07773 N09777 (wrought) N09925 (cast)

N07718 (cast)

N07924 (wrought)

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

Any combination of hydrogen sulfide, chloride concentration, and in situ pH in production environments is acceptable.

pH estimated from laboratory test conditions.

These materials shall also comply with the following: a)

wrought UNS N07031 shall be in either of the following conditions: 1)

solution-annealed to a maximum hardness of 35 HRC;

2) solution-annealed and aged at 760 °C to 871 °C (1 400 °F to 1 600 °F) for a maximum of 4 h to a maximum hardness of 40 HRC. b) wrought UNS N07048, wrought UNS N07773, and wrought UNS N09777 shall have a maximum hardness of 40 HRC and shall be in the solution-annealed and aged condition; c)

wrought UNS N07924 shall be in the solution-annealed and aged condition at a maximum hardness of 35 HRC;

cast UNS N09925 shall be in the solution-annealed and aged condition at a maximum hardness of 35 HRC;

cast UNS N07718 shall be in the solution-annealed and aged condition at a maximum hardness of 40 HRC.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.32 — Environmental and materials limits for precipitation-hardened nickel-based alloys (II) used for any equipment or component Individual alloy UNS number

N07718 N09925

N09925 (wrought, solutionannealed and aged)

N09935

Temperature

Partial pressure H2S pH2S

Chloride conc.

Sulfurresistant?

max °C (°F)

max kPa (psi)

max mg/l

232 (450)

200 (30)

See “Remarks” column

204 (400)

1 400 (200)

See “Remarks” column

199 (390)

2 300 (330)

See “Remarks” column

191 (375)

2 500 (360)

See “Remarks” column

149 (300)

2 800 (400)

See “Remarks” column

135 (275)

See “Remarks” column

Yes

180 000

See “Remarks” column

205 (401)

232 (450)

3 500 (500)

2 800 (400)

180 000

See “Remarks” column

NDSa

Remarks

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

Any combination of hydrogen sulfide, chloride concentration, and in situ pH in production environments is acceptable. Any in situ production environment pH is acceptable for pCO + pH S ≤ 2 2 7 000 kPa (1 000 psi).

NDSa

Any in situ production environment pH is acceptable for pCO + pH S ≤ 2

8 300 kPa (1 200 psi) 232 (450)

3 500 (508)

139 000

See “Remarks” column

NDSa

205 (401)

3 500 (508)

180 000

See “Remarks” column

NDSa

N09945

Any in situ production environment pH is acceptable for pCO + pH S ≤ 2

7 000 kPa (1 000 psi)

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ANSI/NACE MR0175/ISO 15156-3:2015(E) These materials shall also comply with the following: a)

wrought UNS N07718 shall be in any one of the following conditions: 1)

solution-annealed to a maximum hardness of 35 HRC;

hot-worked to a maximum hardness of 35 HRC;

hot-worked and aged to a maximum hardness of 35 HRC;

solution-annealed and aged to a maximum hardness of 40 HRC.

wrought UNS N09925 shall be in any one of the following conditions: 1)

cold-worked to a maximum hardness of 35 HRC;

solution-annealed to a maximum hardness of 35 HRC;

solution-annealed and aged to a maximum hardness of 38 HRC;

cold-worked and aged to a maximum hardness of 40 HRC;

hot-finished and aged to a maximum hardness of 40 HRC.

number-1 wrought UNS N09935 shall be in the solution annealed and aged condition to a maximum hardness of 34 HRC;

number-1 wrought UNS N09945 shall be in the solution annealed and aged condition to a maximum hardness of 42 HRC;

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.33 — Environmental and materials limits for precipitation-hardened nickel-based alloys (III) used for any equipment or component Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

232 (450)

1 000 (150)

See “Remarks” column

220 (425)

2 000 (300)

See “Remarks” column

Yes

204 (400)

4 100 (600)

See “Remarks” column

204 (400)

4 100 (600)

See “Remarks” column

Yes

204 (400)

3 500

180 000

Remarks

N07626 (powder metal) N07716 N07725 (wrought) N07022 (wrought)

See “Remarks” column

(500)

175 (350) N07626 (powder metal) N07716 N07725 (wrought)

See “Remarks” column

Any combination of chloride concentration and in situ pH occurring in production environments is acceptable.

Yes

Any in situ production environment pH is acceptable for pCO2 + pH2S ≤ 7 000 kPa (1 000 psi)

Yes

Any combination of hydrogen sulfide, chloride concentration, and in situ pH in production environments is acceptable.

These materials shall also comply with the following: a) UNS N07626, totally dense hot-compacted by a powder metallurgy process, shall have a maximum hardness of 40 HRC and a maximum tensile strength of 1 380 MPa (200 ksi) and shall be either 1)

solution-annealed [927 °C (1 700 °F) minimum] and aged [538 °C to 816 °C (1 000 °F to 1 500 °F)], or

direct-aged [538 °C to 816 °C (1 000 °F to 1 500 °F)].

b) wrought UNS N07716 and wrought UNS N07725 shall have a maximum hardness of HRC 43 and shall be in the solutionannealed and aged condition; c) wrought UNS N07716 and wrought UNS N07725 in the solution-annealed and aged condition can also be used at a maximum hardness of HRC 44 in the absence of elemental sulfur and subject to the other environmental limits shown for the maximum temperature of 204 °C (400 °F); d)

wrought UNS N07022 shall have a maximum hardness of HRC 39 in the annealed and aged condition.

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N07626 (powder metal) N07716 N07725 (wrought)

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.34 — Environmental and materials limits for precipitation-hardened nickel-based alloys used for wellhead and christmas tree components (excluding bodies and bonnets) and valve and choke components (excluding bodies and bonnets) Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

3.4 (0.5)

See “Remarks” column

Sulfurresistant?

≥4.5

NDSa

Remarks

N05500

Any combination of temperature and chloride concentration occurring in production environments is acceptable.

For these applications, this material shall also comply with the following. Wrought UNS N05500 shall have a maximum hardness of 35 HRC and shall be either a)

hot-worked and age-hardened,

solution-annealed, or

solution-annealed and age-hardened.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.35 — Environmental and materials limits for precipitation-hardened nickel-based alloys used as non-pressure containing internal valve, pressure regulator, and level controller components and miscellaneous equipment Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

Sulfurresistant?

Remarks

Non-pressure-containing internal-valve, pressure-regulator, and level controller components

N07750 N05500

See “Remarks” column

NDSa

Any combination of temperature. pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

See “Remarks” column

NDSa

This alloy has been used in downhole running, setting and service tool applications for temporary service and in temporary surface service tool applications with the exceptions of bodies and bonnets. Environmental limits for this alloy for these applications have not been established.

Miscellaneous equipment

N05500

See “Remarks” column

For these applications, these materials shall also comply with the following: wrought UNS N07750 shall have a maximum hardness of 35 HRC and shall be either 1)

solution-annealed and aged,

solution-annealed,

hot-worked, or

hot-worked and aged.

wrought UNS N05500 shall have a maximum hardness of 35 HRC and shall be either 1)

hot-worked and age-hardened,

solution-annealed, or

solution-annealed and age-hardened.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.36 — Environmental and materials limits for precipitation-hardened nickel-based alloys used as springs Individual alloy UNS Number

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

N07750

See “Remarks” column

N07090

See “Remarks” column

Remarks

See “Remarks” column

NDSa

This material has been used for these components without restriction on temperature, pH2S, chloride concentration, or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters have led to field failures.

See “Remarks” column

NDSa

For this application these materials shall also comply with the following: —

UNS N07750 springs shall be in the cold-worked and age-hardened condition and shall have a maximum hardness of 50 HRC;

— UNS N07090 can be used for springs for compressor valves in the cold-worked and age-hardened condition with a maximum hardness of 50 HRC. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.37 — Environmental and materials limits for precipitation-hardened nickel-based alloys used in gas lift service Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See “Remarks” column

NDSa

Remarks

N05500

This material has been used for these components without restriction on temperature, − pH2S, Cl , or in situ pH in production environments. No limits on individual parameters are set, but some combinations of the values of these parameters might not be acceptable.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment.

A.9.3 Welding of precipitation-hardened nickel-based alloys of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the base metal after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective metal for the weld alloy.

A.10 Cobalt-based alloys (identified as individual alloys) A.10.1 Materials chemical compositions Table D.10 lists the chemical compositions of the cobalt-based alloys shown in Table A.38 to Table A.40.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) A.10.2 Environmental and materials limits for the uses of cobalt-based alloys Table A.38 — Environmental and materials limits for cobalt-based alloys used for any equipment or component Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See “Remarks” column

Yes

Remarks

R30003 R30004 R30035 BS HR.3 R30605 R31233

Any combination of temperature. pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

These materials shall also comply with the following: a)

alloys UNS R30003, UNS R30004, and BS HR.3 shall have a maximum hardness of 35 HRC;

b) UNS R30035 shall have a maximum hardness of 35 HRC except that it can have a maximum hardness of 51 HRC if it is in the cold-reduced and high-temperature aged heat-treated condition in accordance with the minimum time and the temperature of one of the following ageing treatments: Minimum time h

Temperature °C (°F)

704 (1 300)

732 (1 350)

774 (1 425)

788 (1 450)

802 (1 475)

816 (1 500)

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wrought UNS R31233 shall be in the solution-annealed condition and shall have a maximum hardness of 22 HRC;

UNS R30605 shall have a maximum hardness of 35 HRC.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.39 — Environmental and materials limits for cobalt-based alloys used as springs Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See “Remarks” column

NDSa

Remarks

R30003 R30035

For this application, these materials shall also comply with the following: —

UNS R30003 shall be in the cold-worked and age-hardened condition and maximum 60 HRC;

— UNS R30035 shall be in the cold-worked and age-hardened condition and maximum 55 HRC when aged for a minimum of 4 h at a temperature no lower than 649 °C (1 200 °F). No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.40 — Environmental and materials limits for cobalt-based alloys used as diaphragms, pressure measuring devices, and pressure seals Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

Sulfurresistant?

max

°C (°F)

kPa (psi)

mg/l

R30003, R30004, R30260

See “Remarks” column

R30159

See “Remarks” column

Remarks

See “Remarks” column

NDSa

Any combination of temperature. pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

See “Remarks” column

NDSa

For these applications, these materials shall also comply with the following: a)

UNS R30003 and UNS R30004 shall have a maximum hardness of 60 HRC;

UNS R30260 shall have a maximum hardness of 52 HRC;

c) wrought UNS R30159 for pressure seals shall have a maximum hardness of 53 HRC and the primary load-bearing or pressurecontaining direction shall be parallel to the longitudinal or rolling direction of wrought product. No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

A.10.3 Welding of cobalt-based alloys of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the base metal after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective metal for the weld alloy.

A.11 Titanium and tantalum (individual alloys) --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

A.11.1 Materials chemical compositions A.11.1.1 Titanium alloys Table D.11 lists the chemical compositions of the titanium alloys shown in Table A.41. A.11.1.2 Tantalum alloys Table D.12 lists the chemical compositions of the tantalum alloys shown in Table A.42. A.11.2 Environmental and materials limits for the uses of titanium and tantalum alloys

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.41 — Environmental and materials limits for titanium used for any equipment or component Individual alloy Temperature UNS number

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See “Remarks” column

Yes

Remarks

R50250 R50400 R56260 R53400 R56323 R56403 R56404 R58640

Any combination of temperature. pH2S, chloride concentration, and in situ pH occurring in production environments is acceptable.

These materials shall also comply with the following: a)

UNS R50250 and R50400 shall have a maximum hardness of 100 HRB;

UNS R56260 shall have a maximum hardness of 45 HRC and shall be in one of the three following conditions: 1)

annealed;

solution-annealed;

solution-annealed and aged.

c) UNS R53400 shall be in the annealed condition. Heat treatment shall be annealing at (774 ± 14) °C [(1 425 ± 25) °F] for 2 h followed by air-cooling. Maximum hardness shall be 92 HRB; d)

UNS R56323 shall be in the annealed condition and shall have a maximum hardness of 32 HRC;

wrought UNS R56403 shall be in the annealed condition and shall have a maximum hardness of 36 HRC;

UNS R56404 shall be in the annealed condition and shall have a maximum hardness of 35 HRC;

UNS R58640 shall have a maximum hardness of 42 HRC.

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Specific guidelines shall be followed for successful applications of each titanium alloy specified in this part of ANSI/NACE MR0175/ISO 15156. For example, hydrogen embrittlement of titanium alloys can occur if these alloys are galvanically coupled to certain active metals (e.g. carbon steel) in H2S-containing aqueous media at temperatures greater than 80 °C (176 °F). Some titanium alloys can be susceptible to crevice corrosion and/or SSC in chloride environments. Hardness has not been shown to correlate with susceptibility to SSC/SCC. However, hardness has been included for alloys with high strength to indicate the maximum testing levels at which failure has not occurred.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table A.42 — Environmental and materials limits for tantalum used for any equipment or component Individual alloy UNS number

Temperature

Partial pressure H 2S pH S

Chloride conc.

max

°C (°F)

kPa (psi)

mg/l

See “Remarks” column

Sulfurresistant?

See “Remarks” column

NDSa

Remarks

R05200

Any combination of temperature. pH2S, chloride concentration, and in situ pH occurring in production environments are acceptable.

UNS R05200 shall have a maximum hardness of 55 HRB and shall be either —

annealed, or

—

gas tungsten arc-welded and annealed.

No data submitted to ascertain whether these materials are acceptable for service in the presence of elemental sulfur in the environment. a

A.11.3 Welding of titanium and tantalum alloys of this materials group The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the base metal after welding shall not exceed the maximum hardness allowed for the base metal and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective metal for the weld alloy.

A.12 Copper- and aluminium-based alloys (identified as materials types) A.12.1 Copper-based alloys Copper-based alloys have been used without restriction on temperature, pH2S, Cl−, or in situ pH in production environments. NOTE 1 Copper-based alloys can undergo accelerated mass loss corrosion (weight loss corrosion) in sour oil field environments, particularly if oxygen is present. NOTE 2

Some copper-based alloys have shown sensitivity to GHSC.

A.12.2 Aluminium-based alloys

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These materials have been used without restriction on temperature, pH2S, Cl−, or in situ pH in production environments. The user should be aware that mass loss corrosion (weight loss corrosion) of aluminium-based alloys is strongly dependent on environmental pH.

A.13 Cladding, overlays, and wear-resistant alloys A.13.1 Corrosion-resistant claddings, linings and overlays

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ANSI/NACE MR0175/ISO 15156-3:2015(E) The materials listed and defined in A.2 to A.11 can be used as corrosion-resistant claddings, linings, or as weld overlay materials. Unless the user can demonstrate and document the likely long-term in-service integrity of the cladding or overlay as a protective layer, the base material, after application of the cladding or overlay, shall comply with ANSI/NACE MR0175/ISO 15156-2 or this part of ANSI/NACE MR0175/ISO 15156, as applicable. This may involve the application of heat or stress-relief treatments that can affect the cladding, lining, or overlay properties. Factors that can affect the long-term in-service integrity of a cladding, lining, or overlay include environmental cracking under the intended service conditions, the effects of other corrosion mechanisms, and mechanical damage. Dilution of an overlay during application that can impact on its corrosion resistance or mechanical properties should be considered. A.13.2 Wear-resistant alloys A.13.2.1 Wear-resistant alloys used for sintered, cast, or wrought components Environmental cracking resistance of alloys specifically designed to provide wear-resistant components is not specified in ANSI/NACE MR0175/ISO 15156 (all parts). No production limits for temperature, pH2S, Cl−, or in situ pH have been established. Some materials used for wear-resistant applications can be brittle. Environmental cracking can occur if these materials are subject to tension. Components made from these materials are normally loaded only in compression. A.13.2.2 Hard-facing materials Hard facing may be used. Environmental cracking resistance of alloys or surface layers specifically designed to provide hard facing is not specified in ANSI/NACE MR0175/ISO 15156 (all parts). No production limits for temperature, pH2S, Cl−, or in situ pH have been established. Some materials used for hard-facing applications can be brittle. Environmental cracking of the hard facing can occur if these materials are subjected to tension. Unless the user can demonstrate and document the likely long-term in-service integrity of the hard-facing materials, the base material after application of the hard-facing material shall comply with ANSI/NACE MR0175/ISO 15156-2 or this part of ANSI/NACE MR0175/ISO 15156, as applicable.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Annex B (normative) Qualification of CRAs for H2S-service by laboratory testing

B.1 General This Annex specifies minimum requirements for qualifying CRAs for H 2S service by laboratory testing. Requirements are given for qualifying resistance to the following cracking mechanisms: — SSC at ambient temperature; — SCC at maximum service temperature in the absence of elemental sulfur, S0; — HSC of CRAs when galvanically coupled to carbon or low alloy steel, i.e. GHSC. Supplementary requirements concern a) testing at intermediate temperatures when the distinction between SSC and SCC is unclear, and b) SCC testing in the presence of S0. Guidance on the potential for corrosion to cause cracking of CRAs is given in Table B.1. The alloy groups are the same as those used in Annex A. The test requirements of this Annex do not address the possible consequences of sequential exposure to different environments. For example, the consequence of cooling after hydrogen uptake at a higher temperature is not evaluated.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table B.1 — Cracking mechanisms that shall be considered for CRA and other alloy groups

Materials groups of Annex A

Potential cracking mechanisms in H2S servicea, b

Remarks

SSC

SCC

GHSC

Austenitic stainless steels (see A.2)

Some cold-worked alloys contain martensite and can therefore be sensitive to SSC and/or HSC.

Highly-alloyed austenitic stainless steels (see A.3)

—

These alloys are generally immune to SSC and HSC. Low-temperature cracking tests are not normally required.

Solid-solution nickel-based alloys (see A.4)

Some Ni-based alloys in the cold-worked condition and/or aged conditions contain secondary phases and can be susceptible to HSC when galvanically coupled to steel. In the heavily cold-worked and well-aged condition coupled to steel, these alloys can experience HSC.

Ferritic stainless steels (see A.5)

—

Martensitic stainless steels (see A.6)

Alloys containing Ni and Mo can be subject to SCC whether or not they contain residual austenite.

Duplex stainless steels (see A.7)

Cracking sensitivity can be highest at a temperature below the maximum service temperature and testing over a range of temperatures shall be considered.

Precipitation-hardened stainless steels (see A.8)

—

Precipitation-hardened nickel base alloys (see A.9)

Some Ni-based alloys in the cold-worked condition and/or aged conditions contain secondary phases and can be susceptible to HSC when galvanically coupled to steel.

Cobalt-based alloys (see A.10)

—

Titanium and tantalum (see A.11)

See “Remarks” column

Cracking mechanisms depend upon the specific alloy. The equipment user shall ensure appropriate testing and qualification is carried out.

Copper and aluminium (see A.12)

See “Remarks” column

These alloys are not known to suffer from these cracking mechanisms

P indicates primary cracking mechanism.

S indicates secondary, possible, cracking mechanism.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

B.2 Uses of laboratory qualifications B.2.1 General

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An overview of the uses of laboratory qualifications is given in Figure B.1

Key a

This part of ANSI/NACE MR0175/ISO 15156 addresses SSC, SCC, and GHSC of CRAs and other alloys. ANSI/NACE MR0175/ISO 15156-2 addresses SSC, HIC, SOHIC, and SZC of carbon and low alloy steels.

Annex A addresses SSC, SCC, and GHSC of CRAs and other alloys. ANSI/NACE MR0175/ISO 15156-2:2015, Annex A addresses SSC of carbon and low alloy steels.

See final paragraphs of “Introduction” for further information regarding document maintenance.

NOTE

Flowchart omits qualification by field experience as described in ANSI/NACE MR0175/ISO 15156-1.

Figure B.1 — Alternatives for alloy selection and laboratory qualification

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ANSI/NACE MR0175/ISO 15156-3:2015(E) B.2.2 Qualification of manufactured products The user of this part of ANSI/NACE MR0175/ISO 15156 shall define the qualification requirements for the material in accordance with ANSI/NACE MR0175/ISO 15156-1 and Annex B. This definition shall include the application of the following: a) general requirements (see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 5); b) evaluation and definition of service conditions (see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 6);

d) requirements for qualification based upon laboratory testing (see ANSI/NACE MR0175/ ISO 15156-1:2015, 8.3); e) report of the method of qualification (see ANSI/NACE MR0175/ISO 15156-1:2015, Clause 9). Appropriate “test batches” and sampling requirements shall be defined having regard to the nature of the product, the method of manufacture, testing required by the manufacturing specification, and the required qualification(s) (see Table B.1). Samples shall be tested in accordance with Annex B for each cracking mechanism to be qualified. A minimum of three specimens shall be tested per test batch. The test batch shall be qualified if all specimens satisfy the test acceptance criteria. Retesting is permitted in accordance with the following. If a single specimen fails to meet the acceptance criteria, the cause shall be investigated. If the source material conforms to the manufacturing specification, two further specimens may be tested. These shall be taken from the same source as the failed specimen. If both satisfy the acceptance criteria, the test batch shall be considered qualified. Further retests shall require the purchaser’s agreement. Testing of manufactured products may be carried out at any time after manufacture and before exposure to H2S service. Before the products are placed in H2S service, the equipment user shall review the qualification and verify that it satisfies the defined qualification requirements. Products with a qualification that has been verified by the equipment user may be placed into H2S service. B.2.3 Qualification of a defined production route A defined production route may be qualified for the production of qualified material. A qualified production route may be followed to avoid order release testing for H2S cracking resistance. A materials supplier may propose to a materials purchaser that a qualified production route be used to produce qualified materials. The qualified production route may be used if the materials supplier and materials purchaser agree to its use. A qualified production route may be used to produce qualified material for more than one materials user. To qualify a production route, the material supplier shall demonstrate that a defined production route is capable of consistently manufacturing material that satisfies the applicable qualification test requirements of Annex B. The qualification of a production route requires all of the following: a) definition of the production route in a written quality plan that identifies the manufacturing location(s), all manufacturing operations, and the manufacturing controls required to maintain the qualification; b) initial testing of products produced on the defined production route in accordance with B.2.2 and verifying they satisfy the acceptance criteria; 60 Copyright NACE International Provided by IHS under license with NACE No reproduction or networking permitted without license from IHS

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c) material description and documentation (see ANSI/NACE MR0175/ISO 15156-1:2015, 8.1);

ANSI/NACE MR0175/ISO 15156-3:2015(E) c)

periodic testing to confirm that the product continues to have the required resistance to cracking in H2S service. The frequency of “periodic” testing shall also be defined in the quality plan and shall be acceptable to the purchaser. A record of such tests shall be available to the purchaser;

d) retaining and collating the reports of these tests and making them available to material purchasers and/or equipment users. A material purchaser may agree additional quality control requirements with the manufacturer. The accuracy of the quality plan may be verified by site inspection by an interested party. Changes to a production route that fall outside the limits of its written quality plan require qualification of a new route in accordance with a), b), c), and d) above. B.2.4 Use of laboratory testing as a basis for proposing additions and changes to Annex A Changes to Annex A may be proposed (see Introduction). Proposals for changes shall be documented in accordance with ANSI/NACE MR0175/ISO 15156-1. They shall also be subject to the following additional requirements. Representative samples of CRAs and other alloys for qualification by laboratory testing shall be selected in accordance with ANSI/NACE MR0175/ISO 15156-1. Material representing a minimum of three separately processed heats shall be tested for resistance to cracking in accordance with B.3. Test requirements shall be established by reference to the appropriate materials group in Table B.1. Tests shall be performed for the primary cracking mechanisms listed in Table B.1. Tests shall also be performed for the secondary cracking mechanisms listed in Table B.1; otherwise, the justification for their omission shall be included in the test report. For other alloys not covered by Table B.1, the choice of qualification tests used shall be justified and documented. Sufficient data shall be provided to allow the members of ISO/TC 67 to assess the material and decide on the suitability of the material for inclusion into this part of ANSI/NACE MR0175/ISO 15156, by amendment or revision, in accordance with the ISO/IEC Directives, Part 1.

B.3 General requirements for tests B.3.1 Test method descriptions

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The test requirements are based on NACE TM0177 and EFC Publication 17. These documents shall be consulted for details of test procedures. When necessary, suppliers, purchasers, and equipment users may agree variations to these procedures. Such variations shall be documented. B.3.2 Materials The materials tested shall be selected in accordance with the requirements found in ANSI/NACE MR0175/ISO 15156-1:2015, 8.3.2. In addition, consideration shall be given to the following: a) the cracking mechanism for which testing is required (see Table B.1); b) the testing of appropriately aged samples of alloys that can age in service, particularly HSC testing of downhole materials that can be subject to ageing in service (“well ageing”); c)

the directional properties of alloys because cold-worked alloys may be anisotropic with respect to yield strength and for some alloys and products, the susceptibility to cracking varies with the direction of the applied tensile stress and consequent orientation of the crack plane. 61

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ANSI/NACE MR0175/ISO 15156-3:2015(E) B.3.3 Test methods and specimens Primary test methods use constant load, sustained load (proof-ring), or constant total strain (constant displacement) loading of smooth test specimens. Uniaxial tensile (UT) tests, four-point bend (FPB) tests, and C-ring (CR) tests may be performed with the above loading arrangements. Generally, constant load tests using UT specimens are the preferred method of testing homogeneous materials. Test specimens shall be selected to suit the product form being tested and the required direction of the applied stress. A minimum of three specimens shall be taken from each component tested. UT specimens may be taken from welded joints in accordance with EFC Publication Number 17, Figure 8.1. Other specimens taken from welded joints may be tested with weld profiles as intended for service. When double (back-to-back) FPB specimens are used (in accordance with EFC Publication Number 17, Figure 8.2a, or similar), uncracked specimens shall be disqualified as invalid if the opposing specimen cracks. Alternative test methods or specimens may be used when appropriate. The basis and use of such tests shall be documented and agreed with the equipment user. Examples of test methods that may be considered are as follows. — Fracture mechanics tests, e.g. double cantilever beam (DCB) tests, may be used if cracks are unaffected by branching and remain in the required plane. This normally limits DCB tests to SSC and HSC tests. — Tests involving the application of a slow strain rate, e.g. SSRT in accordance with NACE TM0198, interrupted SSRT in accordance with ISO 7539-7 or RSRT in accordance with the method published as NACE CORROSION/97 Paper 58. Tests may utilize testing of full-size or simulated components when appropriate. B.3.4 Applied test stresses/loads for smooth specimens The yield strengths of CRAs used to derive test stresses shall be determined at the test temperature in accordance with the applicable manufacturing specification. In the absence of an appropriate definition of yield strength in the manufacturing specification, the yield strength shall be taken to mean the 0.2 % proof stress of non-proportional elongation (Rp0,2 as defined in ISO 6892-1) determined at the test temperature. Directional properties shall be considered when selecting test specimens and defining test stresses. For welded specimens, the parent metal yield strength shall normally be used to determine test stresses. For dissimilar joints, the lower parent metal yield strength shall normally be used. When design stresses are based on the yield strength of a weld zone that is lower than the yield strength of either adjoining parent metals, the yield strength of the weld zone may be used to determine test stresses. For constant-load tests and sustained-load (proof-ring) tests, specimens shall be loaded to 90 % of the AYS of the test material at the test temperature. For constant total strain (deflection) tests, specimens shall be loaded to 100 % of the AYS of the test material at the test temperature.

Lower applied stresses can be appropriate for qualifying materials for specific applications. The use and basis of such tests shall be agreed with the purchaser and documented. B.3.5 SSC/SCC test environments B.3.5.1 General 62 Copyright NACE International Provided by IHS under license with NACE No reproduction or networking permitted without license from IHS

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NOTE Constant total strain (deflection) tests might not be suitable for materials that can relax by creep when under load.

ANSI/NACE MR0175/ISO 15156-3:2015(E) The following environmental test variables shall be controlled and recorded: — pH S; 2 — pCO ; 2 — temperature; — test solution pH, the means of acidification, and pH control (all pH measurements shall be recorded); — test solution formulation or analysis; — elemental sulfur, S0, additions; — galvanic coupling of dissimilar metals (the area ratio and coupled alloy type shall be recorded). In all cases, the pH2S, chloride, and S0 concentrations shall be at least as severe as those of the intended application. The maximum pH reached during testing shall be no greater than the pH of the intended application. It can be necessary to use more than one test environment to achieve qualification for a particular service. The following test environments may be used either to simulate intended service conditions or to simulate a nominated condition when intended applications are insufficiently defined. Use can be made of nominated test conditions to provide information on the environmental limits within which a CRA or other alloy is resistant to cracking if no specific application is foreseen. Table E.1 may be used to define the test environments for the standard tests for SSC and GHSC (identified as level II and level III, respectively). For type 1 environments (see B.3.5.2), Table E.1 also provides a number of nominated sets of conditions (for temperature, pCO2, pH2S, and chloride concentration) that may be considered. These are identified as levels IV, V, VI, and VII. When using nominated test conditions, all other requirements of this Annex shall be met. NOTE 1 The nominated sets of conditions are not intended to limit the freedom of the document user to test using other test conditions of their choice.

The equipment user should be aware that oxygen contamination of the service environment can influence the cracking resistance of an alloy and should be considered when choosing the test environment. NOTE 2

Reference [15] gives information on the charging of autoclaves.

B.3.5.2 Service simulation at actual H2S and CO2 partial pressures — Type 1 environments In these test environments, the service (in situ) pH is replicated by controlling the parameters that determine pH under field conditions. Test environments shall be established in accordance with the following requirements: a) test limits: the pressure shall be ambient or greater; b) test solution: synthetic produced water that simulates the chloride and bicarbonate concentrations of the intended service. The inclusion of other ions is optional; c)

test gas: H2S and CO2 at the same partial pressures as the intended service;

d) pH measurement: pH is determined by reproduction of the intended service conditions. The solution pH shall be determined at ambient temperature and pressure under the test gas or pure CO2 immediately before and after the test. This is to identify changes in the solution that influence the test pH. Any pH change detected at ambient temperature and pressure is indicative of a change at the test temperature and pressure.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) B.3.5.3 Service simulation at ambient pressure with natural buffering agent — Type 2 environments

a) test limits: the pressure shall be ambient, temperature shall be maximum 60 °C and pH shall be 4,5 or greater; b) test solution: distilled or de-ionized water with sodium bicarbonate (NaHCO3) added to achieve the required pH. Chloride shall be added at the concentration of the intended service. If necessary, a liquid reflux shall be provided to prevent loss of water from the solution; c) test gas: H2S at the partial pressure of the intended service and CO2 as the balance of the test gas. The test gas shall be continuously bubbled through the test solution; d) pH control: the solution pH shall be measured at the start of the test, periodically during the test and at the end of the test, adjusting as necessary by adding HCl or NaOH. The variation of the test pH shall not exceed ±0.2 pH units. B.3.5.4 Service simulation at ambient pressure with acetic buffer — Type 3a and Type 3b environments In these test environments, the service (in situ) pH is replicated by adjusting the buffer capacity of the test solution using an artificial buffer and adding HCl to compensate for the reduced pressure of acid gases in the test. Test environments shall be established in accordance with the following requirements: a) test limits: the pressure shall be ambient, the temperature shall be (24 ± 3) °C; b) test solution: one of the following test solutions shall be used: 1) for general use (environment 3a), distilled or de-ionized water containing 4 g/l sodium acetate and chloride at the same concentration as the intended service; 2) for super-martensitic stainless steels prone to corrosion in solution for environment 3a (environment 3b), de-ionized water containing 0.4 g/l sodium acetate and chloride at the same concentration as the intended service. HCl shall be added to both solutions to achieve the required pH; c) test gas: H2S at the partial pressure of the intended service and CO2 as the balance of the test gas. The test gas shall be continuously bubbled through the test solution; d) pH control: the solution pH shall be measured at the start of the test, periodically during the test and at the end of the test, adjusting as necessary by adding of HCl or NaOH. The variation of the test pH shall not exceed ± 0.2 pH units. B.3.6 Test duration Constant-load, sustained-load, and constant-total-strain tests shall have a minimum duration of 720 h. Tests shall not be interrupted. B.3.7 Acceptance criteria and test report Specimens exposed in constant-load, sustained-load, and constant-total-strain tests shall be assessed in accordance with NACE TM0177, test methods A, and C. No cracks are permissible.

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In these test environments, the service (in situ) pH is replicated by adjusting the buffer capacity of the test solution using a natural buffer to compensate for the reduced pressure of acid gases in the test. Test environments shall be established in accordance with the following requirements:

ANSI/NACE MR0175/ISO 15156-3:2015(E) Specimens exposed in fracture mechanics and slow strain rate tests shall be assessed as required by the test method. Fracture toughness values shall only be valid for substantially unbranched cracks. Acceptance criteria for fracture toughness tests shall be specified by the equipment user. In all cases, any indication of corrosion causing metal loss including pitting or crevice corrosion shall be reported. NOTE The occurrence of pitting or crevice corrosion outside the stressed section of a specimen can suppress SCC of the specimen.

A written test report conforming to the requirements in ANSI/NACE MR0175/ISO 15156-1:2015, Clause 9, shall be completed and retained. B.3.8 Validity of tests Satisfactory test results qualify materials for environmental conditions that are less severe than the test environment. Users shall determine the validity of tests for individual applications. Environmental severity is decreased by the following at any given temperature: — a lower pH2S; — a lower chloride concentration; — a higher pH; — the absence of S0.

B.4 SSC testing Tests shall be performed in accordance with the general requirements for tests given in B.3. Tests shall normally be performed at (24 ± 3) °C [(75 ± 5) °F] in accordance with NACE TM0177 and/or EFC Publication 17. The test temperature may be at the lowest service temperature if this is above 24 °C (75 °F). The use of a test temperature above 24 °C shall be justified in the test report.

B.5 SCC testing without S0 Tests shall be performed in accordance with the general requirements of B.3. SCC testing procedures shall be based on NACE TM0177 and/or EFC Publication 17 subject to the following additional requirements, options, and clarifications: a) the test temperature shall not be less than the maximum intended service temperature. This can require the use of a pressurized test cell;

c) acetic acid and acetates shall not be used for pH control. The solution pH shall be controlled as described in B.3.5.2; d) during initial exposure of specimens to the test environment, the applied load and the environmental conditions shall be controlled so that all test conditions are already established when the test temperature is first attained; e) for constant-total-strain tests, applied stresses shall be verified by measurement; NOTE

It is good practice to verify the deflection calculations in many CRA material specifications.

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b) water vapour pressure shall be allowed for in determining gas-phase partial pressures;

ANSI/NACE MR0175/ISO 15156-3:2015(E) f)

loading procedures used for constant-total-strain tests shall be shown to achieve a stable stress before specimens are exposed to the test environment.

B.6 SSC/SCC testing at intermediate temperatures

For qualification for inclusion by amendment in A.7, duplex stainless steels shall be tested at (24 ± 3) °C [(75 ± 5) °F], (90 ± 3) °C [(194 ± 5) °F], and at the maximum intended service temperature of the alloy.

B.7 SCC testing in the presence of S0 Tests shall be performed in accordance with the previous requirements for SCC tests with the addition that the procedure published in NACE CORROSION/95 Paper 47 shall be implemented for control of S0 additions. The integration of this procedure into CRA test methods is addressed in EFC Publication 17, Appendix S1.

B.8 GHSC testing with carbon steel couple GHSC tests shall be performed in accordance with the previously stated requirements for SSC testing, subject to the following additional requirements, options, and clarifications: a) the CRA specimen shall be electrically coupled to unalloyed (i.e. carbon) steel that is fully immersed in the test solution. The ratio of the area of the unalloyed steel to the wetted area of the CRA specimen shall be between 0,5 and 1 as required by NACE TM0177. Loading fixtures shall be electrically isolated from the specimen and the coupled steel. For application-specific qualifications, the CRA may be coupled to a sample of the lower alloyed material to which it will be coupled in service. b) the test environment shall be NACE TM0177, Solution A under H2S at a pressure of 100 kPa and at a temperature of (24 ± 3) °C [(75 ± 5) °F]. For application-specific qualifications, SSC test environments described in B.3.5 may be used.

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Testing at intermediate temperatures, i.e. between (24 ± 3) °C [(75 ± 5) °F] and the maximum intended service temperature, shall meet the requirements of the equipment user. Testing shall be performed at the specified temperature in accordance with the above requirements for SCC testing.

ANSI/NACE MR0175/ISO 15156-3:2015(E)

Annex C (informative) Information that should be supplied for material purchasing ANSI/NACE MR0175/ISO 15156-1 indicates that cooperation and exchange of information can be necessary between the various users of this part of ANSI/NACE MR0175/ISO 15156, e.g. equipment users, purchasers and manufacturers of equipment, purchasers of materials, and manufacturers and suppliers of materials. The following tables can be used to assist this cooperation. The materials purchaser should indicate the required options in Table C.1 and Table C.2. Table C.1 and Table C.2 also suggest designations that may be included in markings of materials to show compliance of individual CRAs or other alloys with this part of ANSI/NACE MR0175/ISO 15156. The purchase order details should form part of a material's documentation to ensure its traceability. Where selection of materials is based upon laboratory testing in accordance with Annex B, traceability documentation should also include the details of the conditions derived from Table C.2 that were applied during testing. Table C.1 — Information for material purchase and marking Materials purchaser's requirements

Reference clause in ANSI/NACE MR0175/ ISO 15156-3

Remarks

Sour service designation for e marking

Preferred CRA or other alloy a and condition

—

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Materials selection options and other information

Equipment type

Method of selection/ qualification

CRA or other alloy selected from Annex A?

Option A

6.1

Service exposure conditions as shown in Table C.2 (optional)

A.nn

CRA or other alloy qualified in accordance with Annex B?

Option B

6.1, Annex B

See also Table C.2

B, B1, B2, etc.

Either of the above methods of selection/ qualification

Option C

See option A and option B

For use when a purchaser requires a known material that is either listed in Annex A or qualified in accordance with Annex B. The purchaser should indicate the method of qualification below. b

User may insert material type and condition.

User may insert equipment type for which material is required.

Indicate which option is required.

A suggested scheme for designation of listed CRAs to be included in markings of materials is for manufacturers/suppliers to indicate compliance of individual CRAs or other alloys by reference to the materials group clause number, e.g. A.2. For materials qualified to Annex B, the suggested designations are B, B1, B2, B3 (see Table C.2).

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table C.2 — Additional information for SSC, SCC, and GHSC testing and suggested marking Materials purchaser's requirements for cracking resistance and service exposure

Reference in this part of ANSI/NACE MR0175/ ISO 15156

Remarks

Sour service designation b for marking

Resistance to SSC

a c Option 1 ,

B.4

—

Resistance to SCC

a c Option 2 ,

B.5 to B.7

—

Resistance to GHSC

a c Option 3 ,

B.8

—

Resistance to SSC, SCC, and GHSC

a c Option 4 ,

B.4 to B.8

—

Cracking qualification test

CO2 pressure, Description kPa of service H S pressure, 2 conditions kPa documented in Temperature, °C accordance In situ pH with

—

ANSI/NACE Cl− or other MR0175/ISO halide, mg/l 15156-1 0

—

Present or absent

Laboratory test requirements

—

Non-standard test stress, % AYS

—

Specimen type

—

B.3

—

— — B.3

—

Indicate which option(s) is (are) required.

For materials qualified to Annex B, the suggested designations for marking are B, B1, B2, and B3 where B1 is SSC, B2 is SCC, B3 is GHSC, and B indicates that the material has been shown to be resistant to all three cracking mechanisms. Test conditions to be appropriate to the service conditions shown in this table (see also B.2 and B.3).

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Annex D (informative) Materials chemical compositions and other information

D.1 The tables that follow are included for the convenience of the users of this part of NACE MR0175/ISO 15156 and are based on the SAE — ASTM standard. Users are encouraged to confirm the accuracy of the information shown using the latest edition of this SAE — ASTM standard. D.2 These tables provide a link between the UNS numbers used in the tables of Annex A and the chemical compositions of the alloys to which they refer. Document users are encouraged to consult the SAE — ASTM standard which gives a written description of each alloy, its chemical composition, common trade names, and cross references to other industry specifications. --``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

D.3 Alloy acceptability depends upon actual chemical composition within the ranges shown and upon any additional chemical composition, heat treatment, and hardness requirements listed for the alloy in Annex A. Some alloy chemical compositions that comply with the tables do not meet these additional qualification requirements. NOTE 1 ISO 15510 [2] provides assistance for the cross-referencing for some UNS numbers to other standards. ISO 13680 [1] provides information relating to materials, their chemical compositions, and their availability for use as casing, tubing, and coupling stock. NOTE 2 Mass fraction, w, is often expressed in US customary units as parts per million by weight and in SI units as milligrams per kilogram. The mass fractions given in the tables of this Annex are expressed as percentage mass fractions, 1 % being equal to 1 g per 100 g. NOTE 3

For Tables D.1, D.2, D.5, D.6, D.7, and D.8, the balance of composition up to 100 % is Fe.

NOTE 4 For Tables D.1, D.2, and D.7, the values of (Ni + 2Mo) and/or FPREN have been rounded to whole numbers. They are provided for guidance only.

Table D.1 — Chemical compositions of some austenitic stainless steels (see A.2 and D.3) UNS

maxa

max

Other

FPREN

Ni + 2Mo

max

wCr

wNi

wMn

wSi

wMo

J92500

0.03

17.0 to 21.0

8.0 to 12.0

1.50

2.00

0.04

—

17 to 21

8 to 12

J92600

0.08

18.0 to 21.0

8.0 to 11.0

1.50

2.00

0.04

—

18 to 21

8 to 11

J92800

0.03

17.0 to 21.0

9.0 to 13.0

1.50

0.04

2.0 to 3.0

—

24 to 31

13 to 19

0.28 to 18.0 to 0.35 21.0

8.0 to 11.0

0.75 to 1.50

1,00

0,04

1.00 to 1.75

—

Otherb

23 to 30

10 to 15

9.0 to 12.0

1.50

2.00

0.04

2.0 to 3.0

—

24 to 31

13 to 18

J92843 J92900

0.08

18.0 to 21.0

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S20100

0.15

16.0 to 18.0

3.5 to 5.5

5.5 to 7.5

1.00

0.060

0.030

—

0.25

—

20 to 22

4 to 6

S20200

0.15

17.0 to 19.0

4.0 to 6.0

7.5 to 10.0

1.00

0.060

0.030

—

17 to 19

4 to 6

0.12 to 16.0 to 1.00 to 14.0 to 0.25 18.0 1.75 15.5

1.00

0.060

0.030

—

16 to 18

1 to 2

S20500 S20910

0.06

20.5 to 11.5 to 23.5 13.5

4.0 to 6.0

1.00

0.040

0.030

1.5 to 3.0

0.20 to 0.40

Otherc

29 to 38

15 to 20

S30200

0.15

17.0 to 19.0

8.0 to 10.0

2.00

1.00

0.045

0.030

—

17 to 19

8 to 10

S30400

0.08

18.0 to 20.0

8.0 to 10.5

2.00

1.00

0.045

0.030

—

18 to 20

8 to 11

S30403

0.03

18.0 to 20.0

8.0 to 12.0

2.00

1.00

0.045

0.030

—

18 to 20

8 to 12

S30500

0.12

17.0 to 10.0 to 19.0 13.0

2,00

1.00

0.045

0.030

—

17 to 19

10 to 13

S30800

0.08

19.0 to 10.0 to 21.0 12.0

2.00

1.00

0.045

0.030

—

19 to 21

10 to 12

S30900

0.20

22.0 to 12.0 to 24.0 15.0

2.00

1.00

0.045

0.030

—

22 to 24

12 to 15

S31000

0.25

24.0 to 19.0 to 26.0 22.0

2.00

1.50

0.045

0.030

—

24 to 26

19 to 22

S31600

0.08

16.0 to 10.0 to 18.0 14.0

2.00

1.00

0,045

0.030

2.0 to 3.0

—

23 to 28

14 to 20

S31603

0.030

16.0 to 10.0 to 18.0 14.0

2.00

1.00

0.045

0.030

2.0 to 3.0

—

23 to 28

14 to 20

S31635

0.08

2.00

1.0

0.045

0.030

2 to 3

0.10

Otherd

23 to 30

14 to 20

S31700

0.08

18,0 to 11.0 to 20.0 15.0

2.00

1.00

0.045

0.030

3.0 to 4.0

—

28 to 33

17 to 23

S32100

0.08

17.0 to 19.0

9.0 to 12.0

2.00

1.00

0.045

0.030

—

Otherd

17 to 19

9 to 12

S34700

0.08

17.0 to 19.0

9.0 to 13.0

2.00

1.00

0.045

0.030

—

Othere

17 to 19

9 to 13

S38100

0.08

17.0 to 17.5 to 19.0 18.5

2.00

1.50 to 2.50

0.03

0.030

—

17 to 19

18 to 19

16 to 18

10 to 14

Where a range is shown, it indicates min to max percentage mass fractions.

Cu, 0.50 % max; Ti, 0.15 to 0.50 %; W, 1.00 % to 1.75 %; Nb + Ta, 0.30 to 0.70 %.

Nb, 0.10 % to 0.30 %; V, 0.10 % to 0.30 %.

Minimum value of Ti shall be five times the percentage mass fraction of carbon.

Minimum value of Nb shall be 10 times the percentage mass fraction of carbon.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.2 — Chemical compositions of some highly alloyed austenitic stainless steels (see A.3 and D.3) UNS

max

maxa

max

FPREN

Ni + 2Mo

wCr

wNi

wMn

wSi

wMo

wCu

S31254

0.020

19.5 to 20.5

17.5 to 18.5

1.00

0.80

0.030

0,010

6.0 to 6.5

0.18 to 0.22

0.50 to 1.00

—

42 to 45

30 to 32

J93254

0.025

19.5 to 20.5

17.5 to 19.7

1,20

1.0

0.45

0.010

6.0 to 7.0

0.18 to 0,24

0.50 to 1.00

—

42 to 47

30 to 34

J95370b

0.03

24 to 25

17 to 18

8 to 9 0.50

0.030

0.010

4 to 5

0.7 to 0.8

0 to 0.50

0 to 0,10

48 to 54

25 to 28

S31266

0.030

23.0 to 25.0

21.0 to 24.0

2.0

1.00

0.035

0.020

5.0 to 7.0

0.35 to 0.60

0.50 to 3.00

1.00 to 3.00

46 to 62

31 to 38

S32200

0.03

20.0 to 23.0

23.0 to 27.0

1.0

0.5

0.03

0.005

2.5 to 3.5

—

28 to 35

28 to 34

S32654

0.02

24.0 to 25.0

21.0 to 23.0

2.00 to 4.00

0.50

0.03

0.005

7.00 to 8.00

0.45 to 0.55

0.30 to 0.60

—

54 to 60

35 to 39

N08007

0.07

19.0 to 22.0

27.5 to 30.5

1.50

1.5

—

2.00 to 3.00

—

3.00 to 4.00

—

26 to 32

32 to 37

N08020

0.07

19.0 to 21.0

32.0 to 38.0

2.00

1.00

0.045

0.035

2.0 to 3.0

—

3.00 to 4.00

—

25.6 to 30.9

36 to 44

0.05

21.0 to 23.0

25.0 to 27.0

2.5

1.0

0.04

0.03

4.0 to 6.0

—

34 to 43

33 to 39

N08367 0.030

20.0 to 22.0

23.5 to 25.5

2.00

1.00

0.04

0.03

6.00 to 7.00

0.18 to 0.25

0.75 max.

—

43 to 49

36 to 40

N08904

0.02

19.0 to 23.0

23.0 to 28.0

2.00

1.00

0.045

0.035

4.00 to 5.00

—

1 to 2

—

32 to 40

31 to 38

N08925

0.02

19.0 to 21.0

24.0 to 26.0

1.00

0.50

0.045

0.030

6.0 to 7.0

0.10 to 0.20

0.50 to 1.50

—

40 to 47

36 to 40

N08926 0.020

19.0 to 21.0

24.0 to 26.0

2.0

0.5

0.03

0.01

6.0 to 0.15 0.5 to 7.0 to 0.25 1.5

—

41 to 48

36 to 40

N08320

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Where a range is shown, it indicates min. to max. percentage mass fractions.

Additional elements, expressed as percentage mass fractions, are Al, 0.01 % max; A, 0.01 % max; B, 0.003 % to 0.007 %; Co, 0.25 % max; Nb, 0.10 % max; Pb, 0.01 % max; Sn, 0.010 % max; Ti, 0.10 % max; and V, 0.10 % max. b

wNb shall be eight times wC (% mass fraction) with a maximum of 1 %.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.3 — Chemical compositions of some solid-solution nickel-based alloys (see A.4 and D.3) UNS

maxa

maxa maxa maxa

maxa maxa maxa maxa maxa

Nb + Ta

maxa

maxa maxa maxa

Al maxa

wCr

wNi

wFe

wMn

wSi

wMo

wCo

wCu

wTi

wNb+Ta

wNb

wAl

N06002

0.05 20.5 bal.b 17.0 to to to 0.15 23.0 20.0

1.00

8.0 to 10.0

0.5 to 2.5

—

0.04 0.030

—

0.2 to 1.0

—

N06007

0.05 21.0 bal.b 18.0 to to 23.5 21.0

1.0 to 2.0

1.00

5.5 to 7.5

2.5

1.5 to 2.5

0,04

0,03

—

1.75 to 2.5

—

1.00

—

2.0 to 6.0

0.50

0.08 12.5 to 14.5

2.5

—

0.02

—

0.35

2.5 to 3.5

—

0.03 28.0 bal.b 13.0 to to 31.5 17.0

1.5

0.8

4.0 to 6.0

5.0

1.0 to 2.4

0.04

0.02

—

0.3 to 1.5

0.30 to 1.50

0,04

1.5 to 4.0

—

1.5

0.5

0.10 15.0 to 16,5

0.3

—

0.015 0.005

—

0.1 to 0.4

N06060

0.03 19.0 54.0 bal.b to to 22.0 60.0

1.50

0.50 12.0 to 14.0

—

1.00 0.030 0.005

—

1.25

—

1.25

—

N06110

0.15 27.0 bal. b to 33.0

1.50

—

2.00

—

4.00

—

1.50

N06250

0.02 20.0 50.0 bal.b to to 23.0 53.0

1.0

0.09 10.1 to 12.0

—

1.00 0.030 0.005

—

1.00

—

N06255

0.03 23.0 47.0 bal.b to to 26.0 52.0

1.00

1.0

6.0 to 9.0

—

1.20

0.69

—

3.0

—

N06625

0.10 20.0 bal.b to 23.0

5.0

0.50

8.0 to 10,0

—

0.015 0.015 0.40

—

3.15 to 4.15

—

0.40

N06686 0.010 19.0 bal.b to 23.0

5.0

0.75

0.08 15.0 to 17.0

—

0.04

0.02 to 0.25

—

3.0– 4.4

—

N06950 0.015 19.0 50.0 15.0 to min to 21.0 20.0

1.00

8.0 to 10,0

2.5

0.5

0.04 0.015

—

0.50

—

0.04

1.0

—

N06952

0.03 23.0 48.0 bal.b to to 27.0 56.0

1.0

6.0 to 8.0

—

0.5 to 1.5

0.03 0.003

0.6 to 1.5

—

N06975

0.03 23.0 47.0 bal.b to to 26.0 52.0

1.0

5.0 to 7.0

—

0.70 to 1.20

0.03

0.70 to 1.50

—

N06985 0.015 21.0 bal.b 18.0 to to 23.5 21.0

1.00

6.0 to 8.0

5.0

1.5 to 2.5

0.04

0.03

—

0.50

—

1.5

—

N06022 0.015 20.0 bal.b to 22.5 N06030

N06059 0.010 22.0 bal.b to 24.0

—

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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—

8.00 12.0 to 12.0

—

0.03

—

0.03

002

ANSI/NACE MR0175/ISO 15156-3:2015(E) N07022d 0.010 20.0 bal.b to 21.4

1.8

0.5

0.08 15.5 to 17.4

1.0

0.5

N08007

0.07 19.0 27.5 bal.b to to 22.0 30.5

1.50

1.50 2.00 to 3.00

—

3.00 to 4.00

N08020

0.07 19.0 32.0 bal.b to to 21.0 38.0

2.00

1.00

2.0 to 3.0

—

N08024

0.03 22.5 35.0 bal.b to to 25.0 40.0

1.00

0.50

3.5 to 5.0

N08026

0.03 22.0 33.0 bal.b to to 26.0 37.2

1.00

N08028

0.03 26.0 29.5 bal.b to to 28.0 32.5

N08032

0.01

—

0.8

—

0.5

—

3.00 0.045 0.035 to 4.00

—

8xC to 1.00c

—

0.50 0.035 0.035 to 1.50

—

0.15 to 0.35

—

0.50 5.00 to 6.70

—

2.00 to 4.00

0.03

—

2.50

1.00

3.0 to 4.0

—

0.6 to 1.4

0.030 0.030

—

bal.b

0.4

0.3

4.3

—

0.015 0.002

—

N08042

0.03 20.0 40.0 bal.b to to 23.0 44.0

1.0

0.5

5.0 to 7.0

—

1.5 to 3.0

0.03 0.003

0.6 to 1.2

—

N08135

0.03 20.5 33.0 bal.b to to 23.5 38.0

1.00

0.75

4.0 to 5.0

—

0.70

0.03

—

0.2 to 0.8

—

N08535 0.030 24.0 29.0 bal.b to to 27.0 36.5

1.00

0.50

2.5 to 4.0

—

1.50

0.03

—

N08825

0.05 19.5 38.0 bal.b to to 23.5 46.0

1.00

0.5

2.5 to 3.5

—

1.5 to 3.0

—

0.03

0.6 to 1.2

—

0.2

N08826

0.05 19.5 38.0 22.0 to to min. 23.5 46.0

1.00

2.5 to 3.5

—

1.5 to 3.0

0.030 0.030

—

0.60 to 1.20

—

N08932 0.020 24.0 24.0 bal.b to to 26.0 26.0

2.0

0.50

4.7 to 5.7

—

1.0 to 2.0

0.025 0.010

—

0.17 to 0.25

—

N10002

0.08 14.5 bal.b to 16.5

4.0 to 7.0

1.00

1.00 15.0 to 17.0

2.5

—

0.040 0.030

—

0.35

3.0 to 4.5

—

N10276

0.02 14.5 bal.b to 16.5

4.0 to 7.0

1.00

0.08 15.0 to 17.0

2.5

—

0.030 0.030

—

0.35

3.0 to 4.5

—

CW12M W

0.12 15.5 bal.b to 17.5

4.5 to 7.5

1.0

16.0 to 18.0

—

0.040 0.030

—

0.20 to 0.4

3.75 to 5.25

—

CW6MC

0.06 20.0 bal.b to 23.0

5.0

1.0

8.0 to 10.0

—

0.015 0.015

—

3.15 to 4.5

1.0

—

0.025 0.015

—

Where a range is shown, it indicates min to max percentage mass fractions.

“Bal.” is the balance of composition up to 100 %.

c d

wNb shall be eight times wC (% mass fraction), with a maximum of 1 %. Additional elements by mass fraction: wTa = 0.2 % max and wB = 0.006 % max.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.4 — Chemical compositions of some copper nickel alloys (see A.4) UNS

max

wCu

% N04400 N04405

Nia

max

wNi

wFe

wMn

wSi

0.3

Bal.b

63.0 to 70.0

2.50

2.00

0.50

0.024

0.30

Bal.b

63.0 to 70.0

2.5

2.0

0.50

0.025 to 0.060

Where a range is shown, it indicates min to max percentage mass fractions %.

Bal. is the balance of composition up to 100 %.

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.5 — Chemical compositions of some ferritic stainless steels (see A.5) UNS

max

maxa

max

Other

max

maxa

wCr

wNi

wMn

wSi

wMo

S40500

0.08

11.5 to 14.5

—

1.00

—

0.040

0.030

Al 0.10 to 0.30

S40900

0.08

10.5 to 11.75

0.50

1.00

—

0.045

Ti 6 × C to 0.75b

S43000

0.12

16.0 to 18.0

—

1.00

—

0.040

0.030

—

S43400

0.12

16.0 to 18.0

—

1.00

0.75 to 1.25

—

0.040

0.030

—

S43600

0.12

16.0 to 18.0

—

1.00

0.75 to 1.25

—

0.040

0.030

(Nb + Ta) 5 × C to 0.70b

S44200

0.20

18.0 to 23.0

—

1.00

—

0.040

0.030

—

S44400

0.025

17.5 to 19.5

1.00

1.75 to 2.50

0.025

0.040

0.030

[Nb + 0,2 × Ti+ 4(C + N)] 0.8b

S44500

0.02

19.0 to 21.0

0.60

1.00

—

0.03

0.040

0.012

Nb 10(C + N) to 0,8b; Cu 0,30 to 0,60

S44600

0.20

23.0 to 27.0

—

1.50

1.00

—

0.25

0.040

0.030

—

S44626

0.06

25.0 to 27.0

0.50

0.75

0.75 to 1.50

0.04

0.040

0.020

Ti 7 × (C + N) minb and 0.20 to 1.00, Cu 0.20

S44627

0.010

25.0 to 27.0

0.50

0.40

0.75 to 1.50

0.015

0.020

Nb 0.05 to 0.20, Cu 0.20

S44635

0.025

24.5 to 26.0

3.50 to 4.50

1.00

0.75

3.50 to 4.50

0.035

0.040

0.030

[Nb + 0.2 × Ti+ 4(C + N)] 0.8b

S44660

0.025

25.0 to 27.0

1.50 to 3.50

1.00

2.50 to 3.50

0.035

0.040

0.030

[Nb + 0,2 × Ti+ 4(C + N)] 0.8b

S44700

0.010

28.0 to 30.0

0.15

0.30

0.20

3.5 to 4.2

0.020

0.025

0.020

(C + N) 0.025 Cu 0.15

S44735

0,030

28.0 to 30.0

1,00

1.00

3.60 to 4.20

0.045

0.040

0.030

[Nb + Ta – 6 (C + N)] 0.20 to 1.00b

S44800

0,010

28.0 to 30.0

2.0 to 2.5

0.30

0.20

3.5 to 4.2

0.020

0.025

0.020

(C + N) 0.025b, Cu 0.15

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Where a range is shown, it indicates min to max percentage mass fractions.

Expresses value(s) for element(s) by reference to the mass fraction of other elements, e.g. Ti 6 × C to 0.75 indicates a value for Ti between six times wC (%) and 0.75 %. b

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.6 — Chemical compositions of some martensitic stainless steels (see A.6) Name

Other

maxa

wCr

wNi

wMo

wSi

wMn

maxa

S41000

—

0.15

11.5 to 13.5

—

0.04

0.03

—

S41425

—

0.05

12 to 15

4 to 7

1.5 to 2

0.5

0.02

0.005

0.5 to 1.0

0.06 to 0.12

Cu 0.3

S41426

—

0.03

11.5 to 13.5

4.5 to 6.5

1.5 to 3

0.5

0.02

0.005

0.5

—

Ti 0.01 to 0.5; V 0.5

S41427

—

0.03

11.5 to 13.5

4.5 to 6,0

1.5 to 2.5

0.50

0.02

0.005

1.0

—

Ti 0.01; V 0.01 to 0.50

S41429

—

0.1

10.5 to 14.0

2.0 to 3.0

0.4 to 0.8

1.0

0.03

0.75

0.03

S41500

—

0.05

11.5 to 14.0

3.5 to 5.5

0.5 to 1.0

0.6

0.03

0.5 to 1.0

—

S42000

—

0.15 mina

12 to 14

—

0.04

0.03

—

S42400

—

0.06

12.0 to 14.0

3.5 to 4.5

0.3 to 0.7

0.3 to 0.6

0.03

0.5 to 1.0

—

S42500

—

0.08 to 0.2

14 to 16

1 to 2

0,3 to 0,7

0,02

0.01

0.2

—

J91150

—

0.15

11.5 to 14

0.5

1.5

0.04

—

J91151

—

0.15

11.5 to 14

0.15 to 1

0.04

—

J91540

—

0.06

11.5 to 14

3.5 to 4.5

0.4 to 1

0.04

0.03

—

420 M

0.15 to 0.22

12 to14

0.5

—

0.02

0.01

0.25 to 1

—

Cu 0.25

K90941

—

0,15

8 to 10

—

0.9 to 1.1

0.5 to 1

0.03

0.3 to 0.6

—

L80 13 Cr

0.15 to 0.22

12 to 14

0.5

—

0.02

0.01

0.25 to 1

—

Cu 0.25

Min indicates minimum percentage mass fraction. Where a range is shown, it indicates min to max percentage mass fractions.

Additional elements, expressed as percentage mass fractions, are Al, 0.05 % max; B, 0.01 % max; Nb, 0.02 % max; Co, 1.0 % max; Cu, 0. 5 % max; Se, 0.01 % max; Sn, 0.02 % max; Ti, 0.15 % to 0.75 %; V, 0.25 % max. b

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--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

UNS

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.7 — Chemical compositions of some duplex stainless steels (see A.7 and D.3) UNS

maxa

wCr

wNi

wMn

wSi

wMo

wCu

S31200

0.03

24.0 to 26.0

5.5 to 6.5

1.2 to 2.0

0.14 to 0.20

—

0.045

0.03

30 to 36

S31260

0.03

24.0 to 26.0

5.5 to 7.5

0,75

2.5 to 3.5

0.10 to 0.30

0.20 to 0.80

0.10 to 0.50

0.03

34 to 43

S31803

0.03

21.0 to 23.0

4.5 to 6.5

2.50 to 3.50

0.08 to 0.20

—

0.03

0.02

31 to 38

S32404

0.04

20.5 to 22.5

5.5 to 8.5

2.0 to 3.0

0.20

1.0 to 2.0

0.030

0.03

0.01

27 to 36

S32520

0.03

24.0 to 26.0

5.5 to 8.0

1,5

0.8

3.0 to 5.0

0.20 to 0.35

0.50 to 3.00

—

0.035

0.02

37 to 48

S32550

0.04

24.0 to 27.0

4.5 to 6.5

1,5

2.00 to 4.00

0.10 to 0.25

1.5 to 2.5

—

0.04

0.03

32 to 44

S32750

0.03

24.0 to 26.0

6.0 to 8.0

1.2

0.8

3.0 to 5.0

0.24 to 0.32

—

0.035

0.02

38 to 48

S32760

0.03

24.0 to 26.0

6.0 to 8.0

3.0 to 4.0

0.2 to 0.3

0.5 to 1.0

0.03

0.01

38 to 46

S32803b

0.01

28.0 to 29.0

3.0 to 4.0

0,5

0.5

1.8 to 2.5

0.025

—

0.02

0.005

34 to 38

S32900

0.2

23.0 to 28.0

2.5 to 5.0

0.75

1.00 to 2.00

—

0.04

0,03

26 to 35

S32950

0.03

26.0 to 29.0

3.50 to 5.20

0.6

1.00 to 2.50

0.15 to 0.35

—

0.035

0,01

32 to 43

S39274

0.03

24.0 to 26.0

6.0 to 8.0

0.8

2.50 to 3.50

0.24 to 0.32

0.2 to 0.8

1.5 to 2.5

0.03

0.02

39 to 47

S39277

0.025

24.0 to 26.0

6.5 to 8.0

0.8

3.0 to 4.0

0.23 to 0.33

1.2 to 2.0

0.80 to 1.20

0.025 0.002

39 to 46

J93370

0.04

24.5 to 26.5

4.75 to 6.0

1.75 to 2.25

—

2.75 to 3.25

—

0.04

30 to 34

J93345

0.08

20.0 to 27.0

8.9 to 11.0

3.0 to 4.5

0.10 to 0.30

—

0.04

0.025

31 to 47

J93380

0.03

24.0 to 26.0

6.0 to 8.5

3.0 to 4.0

0.2 to 0.3

0.5 to 1.0

0.03

0.025

38 to 46

J93404

0.03

24.0 to 26.0

6.0 to 8.0

1.5

4.0 to 5.0

0.10 to 0.30

—

39 to 47

Where a range is shown, it indicates min to max percentage mass fractions.

Ratio Nb/(C + N) = 12 min; (C + N) = 0.030 % max; Nb = 0.15 % to 0.50 %.

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

FPREN

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.8 — Chemical compositions of some precipitation-hardened stainless steels (see A.8) UNS

max

maxa

max

wCr

wNi

wMn

wSi

wMo

wNb

wTi

wCu

wAl

S66286 0.08

13.5 to 16.0

24.0 to 27.0

2.00

1.00

1.00 to 1.50

—

1.90 to 2.35

—

0.35

S15500 0.07

14.0 to 15.5

3.50 to 5.50

1.00

—

0.15 to 0.45

—

2.50 to 4.50

—

S15700 0.09

14.0 to 16.0

6.50 to 7.75

1.00

2.00 to 3.00

—

S17400 0.07

15.0 to 17.5

3.00 to 5.00

1.00

—

0.15 to 0.45

—

S45000 0.05

14.0 to 16.0

5.00 to 7.00

1.00

0.50 to 1.00

8 × Cb

—

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

Where a range is shown, it indicates min to max percentage mass fractions.

Indicates a minimum value for wNb of eight times the wC (%).

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0.040 0.030 0.001 to 0.01

0.10 to 0.50

0.040 0.030

—

0.75 to 1.50

0.04

0.03

—

3.00 to 5.00

—

0.04

0.03

—

1.25 to 1.75

—

0.030 0.030

—

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.9 — Chemical compositions of some precipitation-hardened nickel base alloys (see A.9) UNS

maxa

maxa max

wCr

wNi

wFe

0.10

20.0 to 23.0

Bal.b

5.0

0.50

N07022e 0.010

20.0 to 21.4

Bal.b

1.8

0.5

N06625

N07031

0.03 22.0 to to 23.0 0.06

maxa maxa maxa maxa maxa maxa max maxa

maxa

wMn wMo

wSi

wNb

wTi

wCu

wAl

wCo

8.0 0.50 to 10.0

3.15 to 4.15

0.40

—

0.40

—

15.5 0.08 to 17.4

—

0,5

0.5

1.0

—

0.006 0.025 0.015

0.003 0.015 0.015 to 0.007

55.0 to 58.0

Bal.b 0.20

1.7 to 2.3

0.20

—

2.10 to 2.60

0.60 to 1.20

1.00 to 1.70

—

0.015 0.015

21.0 to 23.5

Bal.b

18.0 to 21.0

1.0

5.0 to 7.0

0.10

0.5

1.5 to 2.0

1.5 to 2.2

0.4 to 0.9

2.0

—

0.02

0.01

N07090

0.13

18.0 to 21.0

Bal.b

3.0

1.0

—

1.8 to 3.0

—

0.8 to 2.0

15.0 to 21.0

—

N07626

0.05

20.0 to 23.0

Bal.b

6.0

0.50

8.0 0.50 to 10.0

4.50 to 5.50

0.60

0,50

0.40 to 0.80

1.00 0.05

—

0.02

0.015

N07716

0.03

19.0 to 22.0

57.0 to 63.0

Bal.b 0.20

7.0 to 9.5

0.20

2.75 to 4.00

1.00 to 1.60

—

0.35

—

0.015

0.01

N07718

0.08

17.0 to 21.0

50.0 to 55.0

Bal.b 0.35

2.8 to 3.3

0.35

4,75 to 5.50

0.65 to 1.15

0,30

0.20 to 0.80

1.00

—

N07725

0.03

19.0 to 22.5

55.0 to 59.0

Bal.b 0.35 7.00 0.20 to 9.50

2.75 to 4.00

1.00 to 1.70

—

0.35

—

0.015

0.01

N07773

0.03

18.0 to 27.0

45.0 to 60.0

Bal.b 1.00

2.5 to 5,5

0.50

2.5 to 6.0

2.0

—

2.0

—

0.03

0.01

N07924c 0.020

20.5 to 22.5

52.0 min

7.0 0.20 to 13.0

5.5 to 7.0

0.20

2.75 to 3.5

1.0 to 2.0

1.0 to 4.0

0,75

3.0

0.20

—

0.030 0.005

N09777

0.03

14.0 to 19.0

34.0 to 42.0

Bal.b 1.00

2.5 to 5,5

0.50

0.1

—

0.35

—

0.03

0.01

N09925

0.03

19.5 to 23.5

38.0 to 46.0

22.0 1.00 2.50 0.50 min to 3.50

0.50

1.90 to 2.40

1.50 to 3.00

0.10 to 0.50

—

0.03

N09935d 0.030

19.5 to 22.0

34.0 to 38.0

Bal.b

0.20 to 1.0

1.80 to 2.50

1.0 to 2.0

0.50

1.0

—

1.0

3.0 to 5.0

0.50

0.006 0.015 0.015

0.025 0.001

--``,,,`,`,,````,`,``,`,`````,,,-`-`,,`,,`,`,,`---

N07048 0.015

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ANSI/NACE MR0175/ISO 15156-3:2015(E) N09945 0.005 to 0.04

19.5 to 23.0

45.0 to 55.0

Bal.b

1.0

3.0 to 4.0

0.5

2.5 to 4.5

0.5 to 2.5

1.5 to 3.0

0.01 to 0.7

—

0.03

N05500

0.25

—

63.0 to 70.0

2.00 1.50

—

0.50

—

0,35 to 0.85

Bal.b

2.30 to 3.15

—

N07750

0.08

14.0 to 17.0

70.0 min

5.0 to 9.0

—

0.50

0.70 to 1.20

2.25 to 2.75

0.5

0.40 to 1.00

—

0.01

1.00

Min indicates minimum percentage mass fraction. Where a range is shown, it indicates min to max percentage mass fractions.

“Bal.” is the balance of composition up to 100 %.

Additional elements by mass fraction: wW = 0.5 % max and wMg = 0.005 0 % max.

Additional elements by mass fraction: wW = 1.0 % max.

Additional elements by mass fraction: wTa = 0.2 % max and wW = 0.8 % max.

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ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.10 — Chemical compositions of some cobalt-based alloys (see A.10) UNS

maxa

maxa maxa maxa

max

maxa

max

maxa

wCr

wNi

wCo

wFe

wMn

wSi

wMo

wBe

wTi

R30003

0.15

19.0 to 21.0

15.0 to 16.0

39.0 to 41.0

Bal.b 1.5 to 2.5

—

6.0 to 8.0

—

1.00

—

R30004

0.17 to 0.23

19.0 to 21.0

12.0 to 14.0

41.0 to 44.0

Bal.b

1.35 to 1.80

—

2.0 to 2.8

—

0.06

—

2.3 to 3.3

—

R30035 0.025 19.0 to 21.0

33.0 to 37.0

Bal.b

1.0

0.15

0.15 9.0 to 10.5

—

0.015 0.01

—

1.00

—

R30159

0.04

18.0 to 20,0

Bal.b

34.0 8.00 0.20 to to 38.0 10.00

0.20

6.00 to 8.00

0.03

0.02

0.01

—

2.50 to 3.25

—

R30260c 0.05

11.7 to 12.3

Bal.b

41.0 9.8 to 0.40 to 10.4 to 42.0 1.10

0.20 to 0.60

3.70 to 4.30

—

0.20 to 0.30

0.80 to 1.20

3.60 to 4.20

—

R31233

0.02 to 0.10

23.5 7.0 to Bal.b 1.0 to 0.1 to 0.05 4.0 to to 11.0 5.0 1.5 to 6.0 27.5 1.00

—

0.03

0.02

—

1.0 to 0.03 3.0 to 0.12

R30605

0.05 to 0.15

19.0 9.0 to Bal.b to 11.0 21.0

—

13.0 nom.

3.0

2.0

1.00

—

Where a range is shown, it indicates min to max percentage mass fractions.

“Bal.” is the balance of composition up to 100 %.

Additional elements, expressed as percentage mass fractions, are Nb, 0.1 % max; and Cu, 0.30 % max.

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—

ANSI/NACE MR0175/ISO 15156-3:2015(E) Table D.11 — Chemical compositions of some titanium alloys (see A.11) UNS

Other

maxa

wAl

wCr

wFe

wMo

wNi

wSn

wZr

R50250

—

0.10

—

0.20

0.015

—

0.03

—

O 0.18

Bal.b

R50400

—

0.10

—

0.30

0.015

—

0.03

—

O 0.25

Bal.b

R56260

—

Bal.b

R53400

—

0.08

—

0.30

0.015

0.2 to 0.4

0.03

0.6 to 0.9

—

O 0,25

Bal.b

R56323 2.5 to 2.0 to 3.5 3.0

0.08

—

0.25

0.015

—

0.03

—

O 0.15, Ru 0.08 to 0.14

Bal.b

R56403 5.5 to 3.5 to 6.75 4.5

0.10

—

0.40

0.0125

—

0.05

0.3 to 0.8

—

O 0.20, Pd 0.04 to 0.08, Residualsc

Bal.b

R56404 5.5 to 3.5 to 6.5 4.5

0.08

—

0.25

0.015

—

0.03

—

O 0.13, Ru 0.08 to 0.14

Bal.b

—

Bal.b

R58640

maxa maxa

Where a range is shown, it indicates min to max percentage mass fractions.

“Bal.” is the balance of composition up to 100 %.

Residuals each 0,1 % max mass fraction, total 0,4 % ma. mass fraction.

Table D.12 — Chemical composition of R05200 tantalum alloy (see A.11) UNS

R05200a

Other

max

wCo

wFe

wSi

wMo

wNi

wTi

0.01

0.05

0.01

0.005

0.01

0.03

0.01

0.015

Bal.b

Additional elements, expressed as percentage mass fractions, are Nb, 0.05 % max; H, 0.001 % max; and O, 0.015 % max.

“Bal.” is the balance of composition up to 100 %.

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Annex E (informative) Nominated sets of test conditions

The nominated sets of test conditions shown in Table E.1 can be used to help determine acceptable limits for the application of CRAs and other alloys. The “levels” shown in the table were previously established in NACE MR0175. These are retained to provide continuity of terminology with that of the data set on which many of the environmental limits for materials types and individual alloys shown in the tables of Annex A are based. Table E.1 — Test conditions Specific test conditions

Environment al factor

Level I

Temperature °C (°F)

25 ± 3 (77 ± 5)

Level IV

Level V

Level VI

Level VII

90 ± 5 (194 ± 9)

150 ± 5 (302 ± 9)

175 ± 5 (347 ± 9)

205 ± 5 (401 ± 9)

pCO2 MPa (psi)

0.7 (100)

1.4 (200)

3.5 (500)

pH2S MPa (psi)

0.003 (0.4)

0.7 (100)

3.5 (500)

101 000

139 000

180 000

NaCl minimum percentage mass fraction Calculated Cl milligrams per litre

−a

Test conditions defined and documented by the user

Level II

Level III

Test in accordance with B.4

Test in accordance with B.4 and B.8

See B.3.5.1 and B.3.5.2

Optional (see B.7)

Galvanic coupling to steel

Optional; see Clause B.8

Other

See B.3.5.1

The equivalent mg/l concentration for ambient temperature used in Tables A.1 to A.42 was calculated from the

corresponding percentage mass fraction value.

[18]

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ANSI/NACE MR0175/ISO 15156-3:2015(E)

Bibliography

[1]

ISO 13680, Petroleum and natural gas industries — Corrosion-resistant alloy seamless tubes for use as casing, tubing and coupling stock — Technical delivery conditions

[2]

ISO 15510, Stainless steels — Chemical composition

[3]

ASTM A182/A182M, Standard Specification for Forged or Rolled alloy and steel pipe flanges, forged fittings, and valves and parts for high-temperature service

[4]

ASTM A213/A213M, Standard specification for seamless ferritic and austenitic alloy-steel boiler, superheater, and heat-exchanger tubes

[5]

ASTM A276, Standard Specification for Stainless Steel Bars and Shapes

[6]

ASTM A351/A351M, Standard Specification for Castings, Austenitic, Austenitic-Ferritic, for PressureContaining Parts

[7]

ASTM A743/A743M, Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application

[8]

ASTM A744/A744M, Standard Specification for Castings, Iron-Chromium-Nickel, Corrosion Resistant, for Severe Service

[9]

BONIS, M. and CROLET, J-L. How to pressurize autoclaves for corrosion testing under CO2 and H2S pressure, Corrosion, 56, 2000, No. 2, pp. 167-182

[10]

BS HR.35), Specification for nickel-cobalt-chromium-molybdenum-aluminium-titanium heatresisting alloy billets, bars, forgings and parts (nickel base, Co 20, Cr 14.8, Mo 5, Al 4.7, Ti 1.2)

[11]

European Federation of Corrosion Publications No. 16, Guidelines on materials requirements for carbon and low alloy steels for H2S-containing environments in oil and gas production, ISBN 0901716-95-2

[12]

NACE MR0175, Sulfide stress cracking resistant metallic materials for oilfield equipment

[13]

NACE MR0176, Metallic materials for sucker-rod pumps for corrosive oilfield environments

[14]

NACE TM0284, Evaluation of pipeline and pressure vessel steels for resistance to hydrogen induced cracking

[15]

ASM International (ASM), ASM Materials Engineering Dictionary, Ohio, USA

[16]

ASTM E18, Standard Test Method for Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials

[17]

ASTM E384, Standard Test Method for Knoop and Vickers Hardness of Materials

[18]

CRC Handbook of chemistry and Physics6)

5 British Standards Institution, 389 Chiswick High Road, London W4 4AL, UK. 6 Available from CRC online.

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GUIDE

Use of International Standard NACE MR0175/ISO15156 International Standard NACE MR0175/ISO15156 Petroleum and Natural Gas Industries â&#x20AC;&#x201C; Materials for use in H2S-containing Environments in Oil and Gas Production December 2005

2005-0042

The Canadian Association of Petroleum Producers (CAPP) represents 150 companies that explore for, develop and produce natural gas, natural gas liquids, crude oil, oil sands, and elemental sulphur throughout Canada. CAPP member companies produce more than 95 per cent of Canada’s natural gas and crude oil. CAPP also has 130 associate members that provide a wide range of services that support the upstream crude oil and natural gas industry. Together, these members and associate members are an important part of a $100-billion-a-year national industry that affects the livelihoods of more than half a million Canadians.

Review by December 2008

Disclaimer This publication was prepared for the Canadian Association of Petroleum Producers (CAPP) by the members of the CAPP Pipeline Technical Committee. While it is believed that the information contained herein is reliable under the conditions and subject to the limitation set out, CAPP does not, guarantee its accuracy. The use of this report or any information contained will be the user’s sole risk, regardless of any fault or negligence of CAPP or its co-funders.

2100, 350 – 7th Ave. S.W. Calgary, Alberta Canada T2P 3N9 Tel (403) 267-1100 Fax (403) 261-4622

904, 235 Water Street St. John’s, Newfoundland Canada A1C 1B6 Tel (709) 724-4200 Fax (709) 724-4225

Email: communication@capp.ca Website: www.capp.ca

TABLE OF CONTENTS 1

Objective .......................................................................................................................3

Background...................................................................................................................3 2.1

Abbreviated Terms ..........................................................................................4

NACE MR0175 / ISO 15156 Interpretation and Maintenance .................................4

From NACE MR0175 to NACE MR0175/ISO15156 ...............................................5 4.1

Structure of New Document........................................................................................8 5.1

5.2

5.3

Significant changes to previous MR0175: .....................................................5 4.1.1 Responsibilities for Various Users of the Document........................5 4.1.2 Changes that affect only the Carbon Steel Alloys ............................6 4.1.3 Changes that affect only the Corrosion Resistant Alloys .................6 4.1.4 Other Options for Material Qualifications.........................................8 4.1.5 Requirements for Marking (Part 2, Section 9; Part 3, Section 7).....8 Part 1 - General Principles for Selection of Cracking-Resistant Materials..8 5.1.1 Scope of the Standard - Equipment and Component Design (Section 1) ..............................................................................................................9 5.1.2 Service Conditions: Evaluation and Definition (Section 6) .............9 5.1.3 Pre-Qualified Materials Selection Guide (Section 7) .......................9 5.1.4 Material Qualification Alternatives and Implementation (Section 8)9 5.1.5 Materials Qualification Documentation (Section 9) .......................10 Part 2: Cracking-Resistant Carbon and Low Alloy Steels ..........................10 5.2.1 Scope of the Standard - Equipment and Component Design (Section 1) ............................................................................................................10 5.2.2 Carbon and Low Alloy Steels in H2S environments (Section 6)...10 5.2.3 Qualification and Selection (Section 7) ...........................................11 5.2.4 Evaluation for resistance to HIC and SWC (Section 8)..................11 5.2.5 Marking (Section 9) ..........................................................................11 5.2.6 Annexes .............................................................................................12 Part 3: Cracking-Resistant CRAs and Other Alloys....................................12 5.3.1 Scope of the Standard - Equipment and Component Design (Section 1) ............................................................................................................12 5.3.2 Corrosion Resistant Alloys in H2S environments (Section 5) .......12 5.3.3 Qualification and Selection (Section 6) ...........................................12 5.3.4 Purchasing Information and Marking (Section 7)...........................13 5.3.5 Annexes .............................................................................................13

End Userâ&#x20AC;&#x2122;s Application Guideline for MR0175/ISO 15156 ...................................14 6.1

Select Qualification Method (Refer to Appendix C, Figure C.1)...............14 6.1.1 Scope of MR0175/ISO 15156 ..........................................................14

6.2

6.3

6.1.2 Existing Facilities vs. New Projects.................................................14 6.1.3 Existing Facilities..............................................................................15 6.1.4 New Projects......................................................................................15 6.1.5 Alternative Materials Qualification..................................................15 Qualification By Field Experience (Refer to Appendix C, Figure C.2) .....16 6.2.1 Material Qualification by Field Experience ....................................16 6.2.2 Describe and document the materials to be qualified .....................16 6.2.3 Describe and document the service environment............................16 6.2.4 Compile the Service History for a minimum of 2 years .................16 6.2.5 Inspection of the in-service material................................................17 6.2.6 Intended Service Environment <= Documented Service Environment ............................................................................................................17 6.2.7 Report and file documentation .........................................................17 Qualification by Laboratory Testing (Refer to Appendix C, Figure C.3)..18 6.3.1 Material Qualification by Laboratory testing..................................18 6.3.2 Select material type and refer to the applicable part of NACE/ISO standard..............................................................................................18 6.3.3 Select the laboratory qualification option that best fits the application ............................................................................................................18 6.3.4 Identify the Qualification Required .................................................18 6.3.5 Select the Test Method......................................................................18 6.3.6 Establish the Test Conditions ...........................................................18 6.3.7 Specify the Acceptance Criteria for each test method ....................19 6.3.8 Report the Test Results .....................................................................19

Other Issues ................................................................................................................19

References...................................................................................................................19

Participants and Acknowledgements ........................................................................19

Appendices .................................................................................................................21 10.1

MATERIAL SELECTION/QUALIFICATION WORKSHEET ...............34

Equipment/Pipeline Location ....................................................................................34

Material Selection/Qualification ...............................................................................34

Service Conditions .....................................................................................................34 13.1 13.2 13.3

Acceptability Bases for Selection for SSC/SCC Resistant Materials (CLAUSE 7:MR0175/ISO 15156-1) ..............................................................................35 35 Qualification Requirements/Testing Conditions .........................................35

Objective The NACE MR0175/ISO 15156 International Standard for the selection of crackresistant materials for use in H2S-containing environments has had a significant impact on various aspects of the oil & gas industry in Canada. For this reason, CAPP Pipeline Technical Committee felt it was important to create a supporting document, which could be used by industry as a reference tool to: • • •

provide a brief overview of the NACE/ISO publication, outlining the most significant changes and their implication to the industry, provide guidance and assistance on how to apply the new publication using simple to follow flowcharts, and clarification examples, provide sample forms which could be used to meet the intent of the publication.

This document is not intended to supersede the NACE MRO175/ISO 15156 International Standard. It is intended to serve a as a Guide for working with and complying with the NACE MRO175/ISO 15156 International Standard. In the case of any inconsistencies between the NACE MRO175/ISO 15156 International Standard and the guidance provided in this document, the International Standard should be adhered to. 2

Background The first edition of the NACE Standard MR0175 was published in 1975 by the National Association of Corrosion Engineers, now known as NACE International. The objective of NACE Standard MR0175 was to establish limits of H2S partial pressure for precautions against sulfide stress cracking (SSC). It was also designed to provide guidance for the selection and specification of SSC-resistant materials when the H2S thresholds were exceeded. In more recent editions, NACE MR0175 has also provided application limits for some corrosion-resistant alloys, in terms of environmental composition and pH, temperature and H2S partial pressure.1 In a joint, cooperative effort, the members of NACE and the European Federation of Corrosion (EFC) became co-leaders of the ISO/TC 67/WG 7 project. This effort introduced fundamental changes to the MR0175, incorporating industrial practices and testing methodologies previously not addressed by MR0175.2. The first full edition of MR0175/ISO 15156 was published in 2003. As stated above, the new standard addresses issues which were not considered in the previous versions of NACE MR0175-2002 and which may have significant implications for the users of the document. For example, the new standard: •

December 2005

acknowledges, in addition to sulphide stress cracking, other potentially catastrophic failure mechanisms resulting from sour environments. Such mechanisms are specified in MR0175/ISO 15156-1:2001 as chloride stress corrosion cracking, hydrogen-induced cracking and stepwise cracking, stress

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• • •

oriented hydrogen-induced cracking, soft zone cracking and galvanicallyinduced hydrogen stress cracking; addresses the synergistic effects of H2S with other environmental factors (chloride content, temperature, pH, etc.) on the cracking resistance of many approved materials; limits the use of many of the approved metals through additional environmental restrictions which were not taken into account by the previous NACE MR0175 versions; has improved the balloting and approval process for adding new alloys.

Note: All abbreviations used in this document are defined in the NACE MR0175/ISO15156 standard. 2.1

Abbreviated Terms SCC - Stress corrosion cracking

SZC – Soft zone cracking

SSC - Sulfide stress cracking

SWC – Stepwise cracking

GHSC – Galvanically-induced hydrogen stress cracking HIC – Hydrogen-induced cracking SOHIC – Stress-oriented hydrogen-induced cracking 3

NACE MR0175 / ISO 15156 Interpretation and Maintenance NACE STG 32 and ISO/TC67/WG 7 have established a two-tiered hierarchical system for handling the interpretation and maintenance of the MR0175/ISO 15156. • •

Maintenance Panel (MP) – composed of 15 members, each serving for a maximum of 4 years NACE Technology Group TG299, the ISO Oversight Committee (OSC) for the MP - composed of 30-50 members, each serving for a maximum of 5 years.

All maintenance issues such as interpretation, amendments or total revisions must be submitted directly to the designate or focal point appointed by the MP. Each task is considered and voted upon by the MP; if an ‘affirmative’ vote or consensus is reached, the task resolution is forwarded to the OSC for balloting. An exception is made for the interpretation of technical content: a MP ‘affirmative’ vote by-passes the OSC and is forwarded directly to ISO/TC67/WG 7, and only when consensus cannot be reached will the MP forward the task to the ISO Oversight Committee for resolution. The ISO Oversight Committee receives and reviews the ballots sent from the MP. These ballots are presented to the OSC membership for voting. A voting consensus of 2/3rds is considered a ‘positive’ ballot and is forwarded to the

December 2005

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ISO/TC67/WG 7. ‘Negative’ ballots are resolved by building consensus and reballoting the task or making technical changes and re-balloting the task. All resolved ballots are forwarded to the ISO/TC67/WG 7 with a 2/3rds positive consensus, otherwise they are considered ‘dead’. Additional information on the Maintenance Panel and the ISO Oversight Committee deadlines as well as Sample Ballot for Qualifying Materials can be found in Appendix A or on the NACE website: http://www.nace.org/NACE/Content/technical/MR0175/Mr0175index.asp Additional information on the standard and use of it can be found at www.iso15156maintenance. This site allows users of the standard to access other information such as: • • • 4

view the list of Inquiries and Answers provided by the Maintenance Panel participate in the ISO 15156 Users’ Forum, which is an open discussion forum allowing the users to share their views on the document access the FAQ on the ISO 15156

From NACE MR0175 to NACE MR0175/ISO15156 Figure 4.1 illustrates where the information from the various sections of MR01752002 can be found in the new NACE MR0175/ISO15156. The most substantial change in the document was to stainless steels. This category of materials was moved from ferrous metals to non-ferrous metals or NACE MR 0175/ISO 151563, Corrosion-Resistant Alloys. Figure 4.1 – NACE MR 0175 to NACE MR 0175/ISO 15156

4.1

Significant changes to previous MR0175:

4.1.1 Responsibilities for Various Users of the Document In preparation for the publication of NACE MR0175/ISO 15156, one of the most significant changes to NACE MR0175 (2003) was on procurement or end user responsibility. The increased emphasis on end user responsibility was established to ensure the correct material was being selected for the intended environment. In all parts of the NACE MR0175/ISO 15156, the importance of end users responsibility for both material selection and documentation is referenced. Such references are exemplified by NACE MR0175/ISO 15156 2001-1, Clause 6.1: “Before selecting or qualifying materials using other parts of NACE MR0175/ISO 15156, the user of the equipment shall define, evaluate and document the service conditions to which materials may be exposed for each application.”

This indication of equipment/end-user responsibility as well as equipment user/equipment supplier cooperation, can be found throughout the standard; such responsibilities are outlined below:

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It is the Equipment/End User's responsibility to: • • •

select the carbon and low alloy steels, cast irons, CRAs (corrosion-resistant alloys) and other alloys suitable for the intended service. (Part 1: Section 5 & Section 6) document the selection and qualification of materials used in the H2S environment. (Part 1: Section 5 & Section 9) assume the ultimate responsibility for the in-service performance of all materials selected by delegated Engineering Consultants/ Engineering and Procurement Companies (EPC). There is no reference to EPC responsibility in MR0175/ISO15156.

It is the Supplier/Manufacturer’s responsibility to: Although there is no direct reference to supplier/fabricator responsibility in MR0175/ISO15156 the following sections imply responsibility. • •

cooperate and communicate in an exchange of information between the end users and materials suppliers/manufacturers concerning required or suitable service conditions. (Part 1: Section 5) ensure the material purchased meets the end users requirements and the requirements of the standard. (Part 3: Section 7)

Other standards, such as API 6A Annex O, do define manufacturer’s responsibilities in relation to MR0175/ISO15156. 4.1.2 Changes that affect only the Carbon Steel Alloys Regions of environmental or SSC severity. (Figure 1 of Part 2: Clause 7.2.1.2) •

Four severity regions are defined based on the effect of the in situ pH and H2S partial pressure on the carbon and low alloy steels. This differs from previous editions where only the partial pressure of the H2S was considered.

Hardness requirements for welds (Part 2: Clause 7.3.3.2) •

Three different hardness test methods are acceptable for weld procedure qualification: Vickers (HV10 or HV5), Rockwell 15N, and HRC (with specified restrictions). Other test methods require the agreement of the equipment user. This differs from previous editions where HRC was the primary basis of acceptance.

Consideration of HIC/SOHIC/SZC/SWC (Part 2: Section 8) •

Additional cracking mechanisms, which result from the synergy of H2S exposure and various material factors (steel chemistry, hardness and manufacturing method), should be considered. Previous standard versions only considered SSC as the governing cracking mechanism.

4.1.3 Changes that affect only the Corrosion Resistant Alloys Consideration of environmental limits for SCC and GHSC (Part 3: Section 6)

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• •

•

The new standard provides principles for selecting cracking resistant materials for use in the presence of H2S in combination with other environmental factors, such as chlorides. The cracking mechanisms addressed include: SCC caused by the presence of chlorides in the H2S containing environment. For example, austenitic stainless steels (e.g. 304, 316) will be limited to a maximum service temperature of 60°C (140°F) because of their susceptibility to chloride stress corrosion cracking at higher temperatures. In previous editions, only sulfide stress cracking (SSC) was considered; there were no temperature restrictions. GHSC caused by the presence of dissimilar alloys in contact with an H2S environment

New Environmental Restrictions (Part 3: Clause A.1.3) •

Depending on the alloy, environmental restrictions may include: maximum chloride content, maximum H2S partial pressure, maximum temperature, minimum pH, and application limits depending on the presence of free sulfur in the system. In previous editions of MR0175, several legacy materials had no environmental restrictions, implying they were suitable for any sour service environment. For example, wrought precipitation hardening nickel alloy 718 (UNS N07718) had no environmental restrictions in previous editions of MR0175; in the current standard this alloy has H2S partial pressure limitations based on the maximum operating temperature.

•

Some alloys may have a range of acceptable environmental parameters depending on the severity of the in-service conditions. The environmental limits listed in Tables A.2-A.42 give the allowable parameters for the H2S partial pressure, temperature, chloride content and pH. As cracking behavior can be affected by the complex interactions of these parameters, there is some discretionary latitude for interpolation depending on the materials intended application or service conditions; a specific H2S partial pressure or production temperature, chloride content, pH is permitted provided the maximum H2S partial pressure and /or the maximum allowable temperature, chloride content, pH are not exceeded. For example, austenitic steels such as AISI 316 are limited to a maximum of 100 kPa partial pressure of H2S at a maximum temperature of 60oC for any combination of chloride concentration and in situ pH in the production fluid. The same alloy can also be used at 350 kPa partial pressure of H2S and 60oC if the maximum concentration of chlorides is 50mg/l or less.

Deletion of Previously Approved Materials •

December 2005

The general usage of some previously approved materials has been restricted to specified components only. For example, 17-4 martensitic, precipitation hardening stainless steel was deleted from the general usage section, but remains an acceptable

Guide on the Use of International Standard NACE

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material for various components of wellheads and Christmas trees, provided a maximum H2S partial pressure of 0.50 psi and minimum pH of 4.5. Corrosion Resistant Alloy Categories (Part 3: Clause A.1.1) •

In NACE MR0175/ISO 15156, a CRA category is a broad-based group of alloys defined in terms of chemical composition, manufacturing process, and finished condition. These categories or materials groups (austenitic steel, martensitic steels, etc) are further split into material types (similar compositional limits) and individual alloys. For example, Annex A, Table A.2 outlines the environmental and materials limits for the general usage of austenitic steels (AISI 304SS, AISI 316SS, etc). This table is sectioned into general materials type and individual alloys, e.g. UNS S20910. The individual alloys tend to have broader environmental limits than those set for the group. In this case, the UNS S20910; it can be used at a slightly higher temperature than AISI 316 at similar partial pressures of H2S.

4.1.4 Other Options for Material Qualifications The new standard allows the equipment user two options for qualifying materials which do not appear as ‘pre-qualified’ materials in NACE MR0175/ISO 15156: • •

Document a successful laboratory test of the material in an environment at least as severe as the intended service. Document field experience with the material in a specified environment and for a specific equipment.

4.1.5 Requirements for Marking (Part 2, Section 9; Part 3, Section 7) The new standard requires that all compliant materials be made traceable by marking, before delivery. Suitable labeling or documentation is also acceptable. 5

Structure of New Document The new NACE MR0175/ISO 15156 consists of 3 parts: • • • 5.1

Part 1- General Principles for Selection of Cracking-Resistant Materials Part 2- Cracking-Resistant Carbon and Low Alloy Steels Part 3Cracking-Resistant CRAs (Corrosion-Resistant Alloys) and Other Alloys

Part 1 - General Principles for Selection of Cracking-Resistant Materials Part 1 of the NACE MR0175/ISO 15156 addresses the background and general principles for using Parts 2 and 3. A summary of the content described below is presented in a flowchart diagram in Appendix B, see Appendix B.1.

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5.1.1 Scope of the Standard - Equipment and Component Design (Section 1) The general principles for the selection of cracking-resistant materials are outlined in Part 1. This document supplements, but does not replace, the material requirements given in the appropriate design codes, standards or regulations; its intent is to address and apply to: • • • •

all the mechanisms of cracking that can be caused by H2S, excluding loss of material by general or localized corrosion; a selective list of equipment (Table 1 lists the applicable equipment including the permitted exclusions) used in oil and gas production; materials for equipment designed and constructed using conventional elastic design criteria. For design using plastic criteria (strain–based and limit states) use of this standard may not be appropriate. the selection or qualification of metallic materials which are resistant to cracking in defined H2S-containing environments in oil and gas production, but are not necessarily immune under all service conditions (NACE MR0175/ISO 15156-1).

Conversely, NACE MR0175/ISO 15156 is not necessarily intended for or applicable to: • •

equipment used in refining or downstream processes and equipment; or components loaded only in compression. This statement has been omitted from Part1 of NACE MR0175/ISO 15156 but is included in both Part2 and Part3.

Note: All items in this section are repeated in both Part2 and Part3 of the standard. 5.1.2 Service Conditions: Evaluation and Definition (Section 6) • •

Outlines all the service conditions required to evaluate whether or not the standard applies. (Clause 6.1) Specifies how the service conditions can be used in the selection of the material qualification method. (Clause 6.2)

5.1.3 Pre-Qualified Materials Selection Guide (Section 7) Selection of a pre-qualified material means that no additional laboratory testing or documented field experience qualifications are necessary. The materials listed have given acceptable performance under the stated metallurgical, environmental and mechanical conditions based on either previous field experience and/or laboratory testing. 5.1.4 Material Qualification Alternatives and Implementation (Section 8) There are two methods by which a material may be qualified for service in H2Scontaining environments: field experience and laboratory testing. •

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experience, and the severity of the intended service ensuring it does not exceed that of the documented service conditions. (Clause 8.2) Note: The data used to qualify a material based on field service, once submitted to NACE, may be used by the public as reference for identical applications. •

Qualification by Laboratory Testing – is used to qualify materials, which do not qualify as a ‘pre-qualified’ material due to either chemistry or required service conditions. Testing may be conducted under service conditions similar to the limits applied to pre-qualified materials or under service conditions outside these limits. (Clause 8.3) Note: Test requirements as well as the qualification process involved are specified in greater details in Annex B of NACE MR0175/ISO15156-2 and NACE MR0175/ISO15156-3.

5.1.5 Materials Qualification Documentation (Section 9) Materials selected or qualified in accordance with MR0175/ISO 15156 shall have the method of selection documented by reporting the service conditions and the relevant sub-clause pertaining to the pre-qualified material, or the relative field experience (mechanism of cracking addressed, material used and experience), or the relative laboratory testing (mechanism of cracking addressed, material tested, test methodology and results). 5.2

Part 2: Cracking-Resistant Carbon and Low Alloy Steels Part 2 outlines the requirements and recommendations for the selection and qualification of carbon steels, low alloy steels and cast irons for service in equipment used in H2S-containing environments of oil and natural gas production and natural gas treatment plants. A summary of the content described below is presented in a flowchart diagram in Appendix B, see Appendix B.2. 5.2.1 Scope of the Standard - Equipment and Component Design (Section 1) See section 5.1.1 of this document for details. 5.2.2 Carbon and Low Alloy Steels in H2S environments (Section 6) The complex interaction of environment factors and materials properties should be considered in the materials selection for use in H2S-containing environments. The parameters affecting the behavior of carbon and low alloy steels in H2S environments are explicitly listed (metallurgy, H2S partial pressure, pH, chloride content, etc.).

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5.2.3 Qualification and Selection (Section 7) •

•

Two qualification options are outlined for selecting carbon and low alloy steels with resistance to SSC, SOHIC and SZC, although the occurrence of SOHIC and SZC are rare. • Option one (Clause 7.1) - allows the user to specify material using Annex A.2 for systems with an H2S partial pressure greater than or equal to 0.05 psi; while, • Option two (Clause 7.2) - allows the user to qualify and select SSC resistance materials for specific or for ranges of sour service applications. The user must evaluate the severity of the service environment based on a combination of H2S partial pressure and in service pH. Depending on the region of environmental severity extrapolated from the graph given in MR0175/ISO 15156-2 (Figure 1), the user is referred to Annex 2, Annex 3 or Annex 4 for material selection. • Option Three (Clause7.2) - there are two methods by which a material may be qualified for service in H2S-containing environments: field experience and laboratory testing. Hardness Requirements • As hardness control is an acceptable means of demonstrating SSC resistance, hardness testing requirements for the parent material, welds, and HAZ must be considered by the user. Three hardness testing methods are specified: Vickers (HV10 or HV5), Rockwell 15N and HRC (with restrictions). Any other test method requires explicit user approval. (Clause 7.3) • Requirements for weld procedure qualification and acceptance criteria which are based on hardness and options for hardness testing are outlined. (Clause 7.3.3) • Hardness surveys should be specified in all fabrication procedure qualifications for all fabrication methods, which cause hardness changes in the material. Hardness testing shall be specified as part of the qualification for fabrication methods such as burning and cutting if any HAZ remains in the final product. (Clause 7.4)

5.2.4 Evaluation for resistance to HIC and SWC (Section 8) Material chemistry, such as sulfur content and certain manufacturing methods, such as flat rolling and seamless drawing, increase the probability of HIC/SWC. To address this prospect, additional testing and specific acceptance criteria may be required. The details for laboratory testing for HIC/SWC are listed in Annex B of NACE MR0175/ISO15156-2. 5.2.5 Marking (Section 9) Specifies requirements for traceability by marking, labeling and /or documentation. Details listed in Annex E of NACE MR0175/ISO15156-2.

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5.2.6 Annexes • • • • • 5.3

Annex A lists SSC-resistant carbon and low alloy steels, and A.2.4 includes requirements for the use of cast irons. Annex B provides requirements for qualification of carbon and low alloy steels for H2S service by laboratory testing Annex C provide recommendations for calculating the partial pressure of H2S for systems involving gas and or two phase flow (Clause C.1) or liquid phase (Clause C.2) Annex D provides recommendations on the determination of pH based on the partial pressure of H2S and CO2. Annex E provides marking designations for material identification.

Part 3: Cracking-Resistant CRAs and Other Alloys Part 3 gives the requirements and recommendations for the selection and qualification of CRAs (corrosion-resistant alloys) and other alloys for service in equipment used in H2S-containing environments of oil and natural gas production and natural gas treatment plants. A summary of the content described below is presented in a flowchart diagram in Appendix B, see Appendix B.3. 5.3.1 Scope of the Standard - Equipment and Component Design (Section 1) See section 5.1.1 of this document for details. 5.3.2 Corrosion Resistant Alloys in H2S environments (Section 5) As in part 2, all relevant factors (metallurgy, H2S partial pressure, pH, chlorides etc.) affecting the susceptibility of CRAs to cracking must be considered by the user and are explicitly outlined by the standard. 5.3.3 Qualification and Selection (Section 6) The qualification and selection of CRAs for SSC, SCC and GHSC cracking resistance using MR0175/ISO 15156-3 is defined by the intended application and service environmental severity. •

General compliance (Clause 6.1) • The limits for CRA selection vary depending on the material type or the individual alloy. CRA’s and other alloys compliant to part 3 of the standard can be selected from the tables in Annex A. For example, when selecting any austenitic stainless steel for a general application, the service environment limits and material requirements are listed in Table A.2 (Annex A). However, if the austenitic stainless steel is UNS S20910, then the specific limits listed for this particular austenitic grade must be used.

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•

CRA’s can also be qualified based on field experience or by laboratory testing. For general details refer to MR0175/ISO 15156-1 (or Section 5.1.4 of this document), otherwise, more specific details for laboratory testing are given in Annex B. Evaluation of Material Properties (Clause 6.2) • Hardness Requirements - for CRAs hardness testing and acceptance criteria must be specified by the user. The hardness limits for material types or individual alloys are listed in Annex A. For processes, such as welding, which increase a materials susceptibility to SSC, SCC and GHSC, require the consideration of hardness in the weld procedure qualification. Options for hardness testing for weld procedure qualification are Vickers (HV10 or HV5) or Rockwell 15N. Any other test method requires explicit user approval. Note: The use of the HRC method requires specific user approval. • Fabrication - metallurgical changes in CRAs resulting from fabrication, require the user to specify crack-resistance qualification testing for all the affected material. This includes qualification testing for fabrication methods such as burning and cutting if any HAZ remains in the final product. (Clause 6.2.3) PREN number (Clause 6.3, Tables A.24 & A.25-NACE MR0175/ISO 15156-3 Annex A)

The formula for the calculation of PREN number for CRA pitting resistance is given in this section. Some environmental restrictions are placed on certain alloys based on the PREN number 5.3.4 Purchasing Information and Marking (Section 7) Requirements for traceability by marking, labeling and /or documentation are specified, as well as requirements for documentation of the environmental conditions for which a material was qualified. Examples of the purchasing information (Clause 7.1) and potential markings (Clause 7.2) are listed in Annex C of MR0175/ISO15156-3. 5.3.5 Annexes •

• • •

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Annex A materials are identified by materials groups. Each group of alloys are identified by materials type (within compositional limits) or as individual alloys. Acceptable metallurgical conditions and environmental limits are given, for which alloys are expected to resist cracking. Annex B provides requirements for qualification of CRAs (corrosion-resistant alloys) and other alloys for H2S service by laboratory testing. Annex C provides marking designations for material purchasing Annex D provides chemical compositions for CRA’s based on their UNS number.

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End User’s Application Guideline for MR0175/ISO 15156 The purpose of this section is to provide the end user with a guideline on how to approach a material selection project in the light of the NACE MR0175/ISO 15156 specifications. End User decision flow charts are included in Appendix C and must be used in conjunction with section. Note: Each of the paragraph numbers below have been recorded on the corresponding Appendix C charts for easier cross-reference. 6.1

Select Qualification Method (Refer to Appendix C, Figure C.1) 6.1.1 Scope of MR0175/ISO 15156 The end user is responsible for determining the applicability of the NACE MR0175/ISO15156 to their particular project. The applicability of the Standard can be determined in two steps:

1. Use Table 1 of NACE MR0175/ISO 15156-1 for an overall assessment of the applications and corresponding equipment covered by the NACE/ISO standard. • NACE MR0175/ISO 15156 applies to "upstream" oil & gas facilities (e.g downhole, field facilities, pipelines, gas sweetening facilities) • Material selection for refineries and chemical plants is not covered by this standard. 2. Determine the level of H2S in the environment by calculating the partial pressure of H2S. If the PH2S ≥ 0.05psi then the NACE/ISO standard must be used for material selection. Instructions for this calculation are covered in Annex C of NACE MR0175/ISO 15156–2. For "upstream" oil & gas facilities with PH2S ≥ 0.05psi, proceed to step 6.1.2. 6.1.2 Existing Facilities vs. New Projects Once it is established that the document applies, the user has to define the type of application involved. Even though similar options are available for all application types, there are different considerations when selecting materials for existing facilities (such as replacement in kind or small projects on existing installations). For this reason, it may be more advantageous to investigate all methods of material qualifications available to ensure the most economical solution. Situation Examples: • • •

Replacement-in-kind situation - The user has a corroded stem in a valve and wants to purchase a replacement stem of the same material. New Equipment at existing installation – The user has to add a new well tie-in to an existing gathering system New Project - Building a new gathering system

Materials Selection for existing facilities, proceed to step 6.1.3, or in the case of new facilities, proceed to step 6.1.4.

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6.1.3 Existing Facilities For each component/material in an existing facility, check the integrity of the existing material to rule out any environmental cracking, as defined in this document (7.1.3). 6.1.3.1 Material Inspection 6.1.3.1 (a) No Cracking If no cracking is found then proceed to step 6.1.3.2. 6.1.3.1 (b) Cracking Present In case of cracking, different materials may need to be selected for those components. Refer to the list of pre-qualified materials in Annex A of NACE MR0175/ISO 15156 Part 2 and/or Part 3. Cross-reference material to Material Requirements Tables For each un-cracked component, compare the environmental conditions and materialâ&#x20AC;&#x2122;s metallurgical conditions with the requirements listed in Annex A of NACE MR0175/ISO 15156 Part 2 and/or Part 3. A sample form for material selection is presented in Appendix E. If the existing material complies with the requirements of the pre-qualified material, the same material can be used. If the existing material does not comply, proceed to step 6.1.5, Alternative Materials Qualification 6.1.4 New Projects For each component/material in a new project or proposed facility, the material selection must be based on the intended service conditions. If the designs for a new facility are modeled after an existing facility and intended for the same service, the materials requirements can be documented based on the existing facility. For new facilities operating in the same service conditions, refer to 6.1.3: Existing Facilities. If the new project or facility is intended for operation under different, more severe service conditions, the materials selection process cannot be based on previous documentation and must be re-evaluated by the user, refer to NACE MR0175/ISO 15156-1 or Appendix B, Flowchart B.1. 6.1.5 Alternative Materials Qualification For any project (replacement in kind, small projects on existing installations or new projects), a certain material desired for a specific component may not be on the NACE/ISO pre-qualified material lists. In this case, the user has three distinct options, they can:

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1) select a new material which is pre-qualified and referenced in the Annex A Tables, 2) check materialâ&#x20AC;&#x2122;s history of successful use or field experience in an identical application for at least 2 years. If documentation exists to support this history, then proceed to Appendix C, Flowchart C.2. Otherwise, refer to Clause 8.2 of NACE MR0175/ISO15156-1, or 3) use laboratory testing to demonstrate that the material is suitable for the proposed service conditions. This method is further discussed in Section 6.3 or Appendix C, Flowchart C.3. 6.2

Qualification By Field Experience (Refer to Appendix C, Figure C.2) 6.2.1 Material Qualification by Field Experience Qualification by field experience can be used to qualify materials which are not included on the NACE MR0175/ISO 15156 pre-qualified lists. The requirements for this method are described in Clause 8.2 of NACE MR0175/ISO15156-1. The field qualification method can be used for any type of application (such as replacement in kind, small projects at existing installations or new projects) provided that the specified requirements are met. These requirements are discussed in more details in the steps below. 6.2.2 Describe and document the materials to be qualified These requirements are covered in Clause 8.1 of NACE MR0175/ISO15156-1 and include information such as, chemical composition, method of manufacture, strength, hardness, amount of cold work, heat treatment condition and microstructure. This information is usually available to the user through Material Test Reports, which are associated with various components. 6.2.3 Describe and document the service environment The information required for the description of service conditions is covered in Clause 6.1 of NACE MR0175/ISO15156â&#x20AC;&#x201C;1. Service conditions include data on H2S partial pressure, in situ pH, concentration of dissolved chlorides, presence of sulphur, temperature, and stress. Paragraphs 6.2, 8.1, 8.2 and 9.0 provide a description of the documentation required for 2 years successful field service. See Appendix D for a sample spreadsheet of data required. These service conditions should be specified for each material/component exposed through either intended or unintended (accidental) service. 6.2.4 Compile the Service History for a minimum of 2 years At least 2 years of service history must be gathered in the form of documented field experience for any material or equipment/component to be considered

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qualified based on field experience. The field experience documentation should also contain relevant information on maintenance, inspections and repairs. Such documentation can only be acquired through a good maintenance/inspection program with detailed reports on the equipment performance in a particular environment. For example: In a wet sour gas system with Chlorides the 316 SS valve seats have provided over 15 years of service without Cl- stress corrosion cracking failures. In several cases these seats have pitted and have been replaced in kind by the end user. The user can continue to add new valves in this system and replace existing 316SS valve seats as long as the user documents that the old seats did not crack in service. 6.2.5 Inspection of the in-service material Post-service inspections and current inspection records are critical for establishing and documenting the material behavior during operation in known service conditions. In the case of NACE MR0175/ISO 15156, documentation for material qualification by field experience must include an acknowledgement of the mechanism of cracking for which the material is being qualified. If no cracking is evidenced in a post-service inspection, the materialâ&#x20AC;&#x2122;s post-service condition can be documented and the same material re-selected for the same service. If cracking is observed, the mechanism should be identified and documented, and a different material selected for the intended service. 6.2.6 Intended Service Environment <= Documented Service Environment In order for a user to qualify a material using documented field experience, the user must ensure the severity of the intended service for a material or component is less than or equal to the documented service environment. The user should be able to verify this with the data collected in steps 6.2.1 through 6.2.5. If the severity of the intended service condition is within the documented range of field experience, the material qualifies; otherwise, the material must be qualified using laboratory testing as outlined in Section 6.3, below. 6.2.7 Report and file documentation The documentation on materials, service conditions and service history can be used to qualify materials that are not classified as pre-qualified alloys in NACE MR0175/ISO 15156. Keeping this documentation on file for future reference or audit is the end userâ&#x20AC;&#x2122;s responsibility. This documentation can be used to select materials for replacement in kind and/or small projects in existing facilities. However, it can also be used to select materials for new projects, if the metallurgical and service conditions of the project match existing applications. Detailed information on the required content of this documentation is covered in Clause 9, NACE MR0175/ISO1516-1.

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6.3

Qualification by Laboratory Testing (Refer to Appendix C, Figure C.3) 6.3.1 Material Qualification by Laboratory testing This method can be used to qualify materials, which are not on the NACE MR0175/ISO 15156 pre-qualified lists. The general requirements for this method are described in Clause 8.3 of NACE MR0175/ISO15156-1. 6.3.2 Select material type and refer to the applicable part of NACE/ISO standard Laboratory testing requirements for carbon and low alloy steels are covered in Annex B of NACE MR0175/ISO1516-2. Laboratory testing for corrosion resistant alloys and other (non-ferrous) alloys are covered in Annex B of NACE MR0175/ISO1516-Part 3. 6.3.3 Select the laboratory qualification option that best fits the application • •

The manufactured products option allows qualification of certain materials for specific equipment and service conditions defined by the end user. The results cannot be generalized to other applications. The second option pertains to a laboratory testing for the qualification of a production route. This method allows a supplier to qualify the material for service in a specific range of service conditions, which can apply to other end users as well.

6.3.4 Identify the Qualification Required Identification and documentation of the potential cracking mechanism(s) is necessary for material qualification using laboratory testing. The potential cracking mechanisms identified by NACE MR0175/ISO 15156 for carbon and low alloys steels are SSC, SOHIC, SZC, HIC/SWC and for CRA’s, SSC, SCC and GHSC or a combination of mechanisms must be considered. For further details refer to Clause B.3 of either Part 2 or Part3 of NACE MR0175/ISO1516. 6.3.5 Select the Test Method In addition to recording the potential cracking mechanism for which the material resistance is being qualified for, the type, number and the size of the specimens that would best fit the test purpose must be documented. 6.3.6 Establish the Test Conditions The test conditions are determined based on the intended service conditions or maximum critical environment the material will contact. The terms of severity of the testing environment should directly reflect the intended service and applied stress situation. All testing conditions should be documented.

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6.3.7 Specify the Acceptance Criteria for each test method It is the responsibility of the user to specify the acceptance criteria. Criteria are either specified in the Standard or by the user. 6.3.8 Report the Test Results The user is responsible for reviewing the test results and for accepting material’s qualification for the intended application. Keeping this documentation on file for future reference or audit is also the user’s responsibility. These reports can also be used as the starting point for the inclusion of the tested material into the prequalified materials lists of NACE MR0175/ISO15156. 7

Other Issues •

Using older versions of MR0175

The maintenance Panel of NACE MR0175/ISO 15156 does not specifically stop users from referencing older versions however they strongly encourage users to reference the current version. • •

CSA Z662 & other related Canadian references or regulatory requirements API 6A and NACE MR0175/ISO 15156 compliance

Class ZZ has been added to the API 6A list of material classification in order to accommodate the changes to the NACE/ISO standard. 8 References 1) “Introduction”, NACE MR0175/ISO 15156-1 (2001), p. v. 2) “Changes to NACE Standard MR0175-2003”, www.nace.org/NACE/Content/technical/MR0175/MR0175Changes.pdf 3) “Introduction to ISO 15156 maintenance activities”, www.nace.org/nace/Content/technical/MR0175/MaintenanceActivities.pdf 4) NACE MR0175/ISO 15156 International Standard 5) www.iso.org/iso15156maintenance 9 Participants and Acknowledgements The members of the CAPP Sour Materials Subcommittee include: • • • • • • • • •

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Ray Goodfellow – Pangea Solutions Kevin Goerz – Shell Canada Limited Patricia Cameron – Talisman Energy Inc. Irina Ward – Master-Flo Dave Grzyb – Alberta Energy and Utilities Board Jerry Bauman - Cimarron Engineering Karol Szklarz - Shell Canada Jan Anderson- Husky Oil Phil Payne- Nuova Fima

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• • •

Jeff Fournell- Dresser Flow Control Vlad Sizov - Encana Alan Miller – Encana

The members of the CAPP SMS would like to express their gratitude and appreciation to: Jim Skogsberg – ChevronTexaco

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10 Appendices Appendix A: Voting Processes for ISO/TC 67 Interpretation and Maintenance

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Maintenance Panel3 â&#x20AC;&#x201C;

ISO Oversight Committee (TG 299)3 â&#x20AC;&#x201C;

Process for Voting on Assigned Tasks For Interpretation Amendments & Total Revisions

Process for Interpretations, Amendments & Total Revisions of ISO 15156 TG 299 Ballot: Results of 2/3 of the voting members are positive 4 week process (Abstentions are not counted)

Corrigenda and Proposed Technical Interpretation of ISO

Voting - 80% of responses are affirmative Deadline - 4 weeks

PASS Attempt to resolve negative ballots: results of 2/3 of the voting members are positive additional 4 weeks

NO Attempt to resolve negative by building consensus: Voting - 80% of responses are affirmative Deadline - additional 4 weeks

PASS

Re-ballot with technical changes: results of 2/3 of the voting members are positive 4 week process

PASS

NO NO

Pass interpretation on to ISO Oversight Committee (TG 299) for balloting

Attempt to resolve negatives: results of 2/3 of the voting members are positive 4 week process NO

DEAD

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PASS

Sample Ballot Form 1-Ballot Item for NACE MR0175/ISO 15156 (latest edition) SUBMITTING COMPANY: SUBMITTED BY: MAILING ADDRESS: TELEPHONE NUMBER: E-MAIL ADDRESS: MATERIAL: UNS NUMBER (IF KNOWN): SUGGESTED ALTERNATIVE TO NACE MR0175/ISO 15156 (latest edition):

Notes for balloters:The proposal must show the existing test or table form the latest edition of NACE MR0175/ISO 15156 together with the revised text or tale in which precise details of the proposed changes are highlighted. If appropriate, these details shall include, for a given material, an environmental limits of application and any metallurgical limits related to materials chemistry, heat treatment, mechanical properties, hardness, etc. that governs its acceptability within those environmental limits.

MATERIAL DESCIPTION

APPLICATION

SERVICE CONDITIONS

MECHANISM(S) OF CRACKING

FIELD EXPERIENCE

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Sample Ballot (Continued)

FORM 1-BALLOT ITEM FOR NACE MR0175/ISO 15156 (latest edition)

LABORATORY DATA SUMMARY

MECHANISM(S) OF CRACKING

SELECTION, SAMPLING, AND PREPARATION OF TEST SPECIMENS

JUSTIFICATION OF THE TEST ENVIRONMENT AND PHYSICAL TEST CONDITIONS

TEST RESULTS DEMONSTRATING COMPLIANCE WITH NACE MR0175/ISO 15156

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Appendix B: Flow Charts- NACE MR0175/ISO15156 layout B.1. MR0175/ISO15156 â&#x20AC;&#x201C; Part 1: 2001 NACE MR0175/ISO 15156-1:2001

Qualification of Materials for H2S Service

Evaluation/Definition/Documentation of Service Condition (Clause 6)

Selection of Pre-Qualified Materials (Clause 7)

SSC-resistant carbon and low alloy steels refer to MR0175/ISO15156 - Part 2 (Clause 7)

Qualification based upon Documented Field Experience (Clause 8.2)

SSC, SCC-resistant CRAs and other alloys refer to MR0175/ISO15156 - Part 3 (Clause 7)

Documented Material Description Shall meet the requirements of Clause 8.1

2 Years Min. Documented Experience - Shall meet relevant requirements of Clause 6.1

A full examination of the equipment following field use is recommended

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Qualification based upon Laboratory Testing (Clause 8.3)

Sampling of Material (Clause 8.3.2)

Selection of Laboratory Test (Clause 8.3.2)

For Carbon & Low Alloy Steels, refer to MR0175/ISO15156-2 for SSC, HIC, SOHIC and/or SZC test methods

Severity of intended service shall not exceed that of field experience

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Testing Conditions (Clause 8.3.2)

For CRAs & other Alloys, refer to MR0175/ISO15156-3 for SSC, SCC and galvanically induced HIC test methods

Acceptance Criteria (Clause 8.3.2)

B.2. MR0175/ISO15156 â&#x20AC;&#x201C; Part 2: 2003 MR0175/ISO 15156-2:2003

Qualifying Carbon and Low Alloy Materials for H2S Service

Option 1 - Selection of SSC-resistant steels using A.2 (Clause 7.1)

pH2S < 0,3 kPa (0,05psi) (Clause 7.1.1)

pH2S w 0,3 kPa (0,05psi) (Clause 7.1.2)

Normally, no special precautions are required for the selection of steels for use under these condition, never the less, highly susceptible steels can crack.

If the partial pressure of H2S in the gas is equal to or greater than 0,3kPa (0,05psi), SSC-resistant steels shall be selected using A.2

Option 2 - Selection of steels for specific sour service applications or ranges of sour service (Clause 7.2)

Note: Users concerned with the occurrence of SOHIC &/or SZC refer to Option 2

Note: For HIC and SWC, refer to Clause 8

No special precautions are required

Highly susceptible steels may crack

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Testing and qualification in accordance with NACE MR 0175/ISO 15156-1 and Annex B - (Clause 7.2.1.4)

Determination of Environment Severity (See Materials Selection/Qualification Worksheet) - (Clause 7.2.1.2)

Region 0

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Option 3 - Selection of steels for sour service using alternative methods (Clause 7.2)

Documented field experience in accordance with NACE MR 0175/ISO 15156-1 - (Clause 7.2.1.4)

Region 1

Region 2

Region 3

Select steels using A.2, A.3, or A.4

Select steels using A.2 or A.3

Select steels using A.2

Very high strength steels can suffer HSC

Stress concentrations increase cracking risk

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B.3. MR0175/ISO15156 â&#x20AC;&#x201C; Part 3: 2003

MR0175/ISO 15156-3:2003

Qualification of CRAs and Other Alloys for H 2 S Service

Qualification based upon the use of Annex A (Clause 6.1)

Materials are identified by alloy groups or individual alloys, see Sections A.2 - A.13

Acceptable metallurgical conditions are given for each alloy group or individual alloy

Acceptable environmental limits are given for each alloy group or individual alloy

Temperature

H2S Partial Pressure Chloride Concentration

pH Elemental Sulphur

Qualification of manufactured products (Section B.2.2)

Qualification of defined production route (Section B.2.3)

User shall define qualification requirements (Section B.2.3)

Definition shall include:

Written quality plan (Section B.2.3)

General requirements (NACE MR0175/ISO 15156-1, Clause 5) Definition of service conditions (NACE MR0175/ISO 15156-1, Clause 6) Material description and documentation (NACE MR0175/ISO 15156-1, 8.1)

Initial testing of products (Section B.2.3) Periodic confirmation testing (Section B.2.3) Retaining/collating of the test reports (Section B.2.3)

Requirements for qualification based upon laboratory testing (NACE MR0175/ISO 15156-1, 8.3) Report qualification method (NACE MR0175/ISO 15156-1, Clause 9)

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Qualification based upon Documented Field Experience (Clause 6.1)

Qualification based upon Laboratory Testing (Clause 6.1)

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Qualification as a basis for proposing additions and changes to Annex A (Section B.2.4) Proposals subject to following requirements:

CRAs/alloys shall be selected in accordance with NACE MR0175/ISO 15156-1 (Section B.2.4) Product(s) tested have publically available specification (Section B.2.4) Minimum of 3 separately processed heats must be tested (Section B.2.4) Tests shall be performed for both primary & secondary cracking mechanisms (Section B.2.4)

Sufficient data shall be provided to ISO/TC 67 to assess the material (Section B.2.4)

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Satisfactory field experience shall comply with MR0175/ISO15156-1, Clause 8.2 (Clause 6.1, paragraph 5)

Appendix C: End User Decision Flow Charts C.1. Select Qualification Method - refer to Section 6.1 of this document

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Scope of MR0175/ISO 15156 (6.1.1)

Upstream Oil and Gas Production, Natural Gas Sweetening Facilities PH2S> 0.05psi

Refinery, Chemical Plant

Not in Scope of NACE0175/ISO 15156, refer to NACE MR0103

Facility Type (6.1.2)

New Project (6.1.4)

New Facility, Same Service

New Facility, Difference Service

Refer to Appendix B, Flowchart B.1

Existing Facility (6.1.3)

Material Inspections (6.1.3.1)

No Cracks (6.1.3.1a)

Cracks Identified (6.1.3.1b)

Cross-reference material to Material Requirements Tables (6.1.3.2)

Refer to Appendix B, Flowchart B.1

Compliant with NACE MR0175/ISO 15156

Document and Purchase same material. Refer to Appendix E

December 2005

Not Compliant with NACE MR0175/ISO 15156

Qualify Material using Alternative Qualificaiton Procedures (6.1.5)

Qualification by Field Experience

Qualification by Laboratory Testing

Refer to Appendix C, Flowchart C.2

Refer to Appendix C, Flowchart C.23

Guide on the Use of International Standard NACE

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C.2. Qualification by Field Experience - refer to Section 6.2 of this document

Field Experience Qualification Method (6.2.1)

Describe/Document Materials to be Qualified (6.2.2)

Describe/Document Service Environment (6.2.3) - documentation for a minimum of 2 years -

Describe/Document Service (6.2.4) - documentation for a minimum of 2 years service -

Full Inspection of in-service equipment, preferred (6.2.5)

Intended Service <= Documented Service Conditions (6.2.6)

Yes

PASS

No Qualify using Laboratory Testing, see Appendix C.3

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Report and File Documentation (7.2.7)

Page 30

C.3. Qualification by Laboratory Testing - refer to Section 6.3 of this document Laboratory Qualification Method (6.3.1)

Select Material Type (6.3.2)

Carbon and Low Alloy Steels (6.3.3)

CRA (6.3.3)

Select Laboratory Qualification Option (6.2.3) - Manufactured Product - Production Route -

Identify Qualification Required (6.3.4) - SSC Cracking Resistance - SOHIC, HIC/SWC Cracking Resistance -

Identify Qualification Required (6.3.4) - SSC Cracking Resistance - SCC, GHSC Cracking Resistance -

Select Test Method, Specimen details (6.3.5)

Select Test Conditions(6.3.6)

Specify Acceptance Criteria (6.3.7) - Acceptance for SSC Resistance, Part 2, Table B.1 - Acceptance for SOHIC, HIC/SWC Resistance, Part 2, Table B.3 -

Specify Acceptance Criteria (6.3.7) - Acceptance for SSC/SCC, Part 3, Clause B.3.7 -

Report Test Results (6.3.8) User has full responsibility for reporting

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Page 31

Appendix D: Data for Field Qualification Table 1 Material Properties from Material Test Reports or Laboratory Testing Component Description

Material

Heat Treatment

Hardness

Product Form

0.2% Yield Strength

UNS No

Solution annealed, Q&T etc

HRC

Cast, Wrought Etc

MPa

Note: The UNS number will provide the reference to the chemical composition

Table 2: Data Obtained from Field Locations Component Description

H2S

CO2

Cl-

HCO3

mole %

mg/l

Pressure kPa

Temp 0

Elemental Sulphur

Time in Service

Yes/No

Years

Note: Element sulphur could be obtained from solids sample analysis. Table 3: Data obtained from Calculations and Failure Reports Component Description

Partial Pressure of H2S

Maximum applied Stress

In-situ pH

Failed or not Yes/No

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Failure description

Root Cause Analysis

Note: In Situ pH can be calculated using commercially available software

December 2005

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Page 33

Appendix E: Sample Forms 10.1

MATERIAL SELECTION/QUALIFICATION WORKSHEET Carbon and Low Alloy Steels (MR0175 / ISO15156) DATE (yyyy-mm-dd):

11 Equipment/Pipeline Location DISTRICT

FIELD/AREA

FACILITY/PROPERTY

SERIAL #

COMPANY ID #

LICENCE NO. EQUIPMENT #

12 Material Selection/Qualification MATERIAL:

HARDNESS:

WALL THICKNESS:

STRENGTH : YS:

min

max

TS:

CHEMISTRY: ____%C

____%Mn

____%Mo

____%Cr

____%P

____%S

Other:____________________________

13 Service Conditions Cl- / Other Halides:

H2 :

kPa (psi)

N2 :

kPa (psi)

Elemental Sulfur (So) :

H2S :

kPa (psi)

Others (document): e.g. Acetic Acid

CO2 :

kPa (psi)

System Pressure:

ppm (meq/l) present /

absent

kPa

Note: pH H2S < 0.3kPa, no special precaution are required for selection of steels for use under these condition, highly susceptible steel can crack

In Situ pH:

Temperature :

Environmental Severity:

1 temperature = 20oC 2 temperature = 80oC

X – H2S partial pressure, kPa Y – in situ pH

Prescribed Maximum Hardness: 22 HRC

Region 0 – no precautions

Region 2 – use A.2 or A.3

Note: provided they contain < 1% Ni and are not free machining steels and are used in the prescribed heat treated condition, see A.2.1.2.

Region 1 – use A.2, A.3 or A.4

Region 3 – use A.2

December 2005

See MR-0175/ISO 15156 – Annex A (normative)

Guide on the Use of International Standard NACE

Page 34

13.1

Acceptability Bases for Selection for SSC/SCC Resistant Materials (CLAUSE 7:MR0175/ISO 15156-1)

13.2 13.3

Qualification Requirements/Testing Conditions

PREFERRED MATERIAL/GRADE:

EQUIPMENT TYPE

NACE MR0175/ISO15156 REFERENCE: N o t e : U N O F F I C I A L S A M P L E â&#x20AC;&#x201C; U s e r d e f i ne d d o c u m e n t a t i o n .

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Item No. 24185

NACE International Publication 8X294 (2013 Edition)

This Technical Committee Report has been prepared by NACE International Specific Technology Group (STG) 34,* “Review of Published Literature on Wet H2S Cracking of Steels Through 1989.”

This NACE International (NACE) technical committee report represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone from manufacturing, marketing, purchasing, or using products, processes, or procedures not included in this report. Nothing contained in this NACE report is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by letters patent, or as indemnifying or protecting anyone against liability for infringement of letters patent. This report should in no way be interpreted as a restriction on the use of better procedures or materials not discussed herein. Neither is this report intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this report in specific instances. NACE assumes no responsibility for the interpretation or use of this report by other parties. Users of this NACE report are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this report prior to its use. This NACE report may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this report. Users of this NACE report are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this report. CAUTIONARY NOTICE: The user is cautioned to obtain the latest edition of this report. NACE reports are subject to periodic review, and may be revised or withdrawn at any time without prior notice. NACE reports are automatically withdrawn if more than 10 years old. Purchasers of NACE reports may receive current information on all NACE International publications by contacting the NACE FirstService Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 281-228-6200).

Foreword This NACE technical committee report summarizes results of laboratory tests and investigations of field and plant experience presented in various sources of the published literature pertaining to the cracking of steels in wet hydrogen sulfide (H2S) service. Particular attention was devoted to the environmental, fabrication, and metallurgical parameters that play predominant roles in the cracking process. This technical committee report is an interpretational review of the literature. A bibliography is attached at the end of each section, and a reference list is also included at the end of the report, to assist readers who wish to seek further information. A table cross-referencing AISI, (1) ASTM, (2) and UNS (3) designations for materials in this report is given in Appendix A. A review of this published literature appears to indicate that steels in refinery service have the potential to be subjected to conditions of hydrogen charging. These conditions result from the presence of H2S and possibly cyanide species in combination

* John Wodarcyk, Phillips 66, Houston, TX American Iron and Steel Institute (AISI), 1140 Connecticut Avenue, Suite 705, Washington, DC 20036. (2) ASTM International (ASTM), 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. (3) th Unified Numbering System for Metals and Alloys (UNS). UNS numbers are listed in Metals & Alloys in the Unified Numbering System, 10 ed. (Warrendale, PA: SAE International and West Conshohocken, PA: ASTM International, 2004). (1)

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NACE International with alkaline or sometimes acidic pH and aqueous environments. The hydrogen charging and cracking of steels in refinery service is very similar in many regards to that observed to occur in steels in acidic pH environments. The similarities are observed in oil and gas pipeline and production service even though significant differences exist in the chemical nature of the service environments. This report is intended for refineries, equipment manufacturers, and engineering contractors. To present a more complete picture of the cracking characteristics of steels in wet H2S environments, this report contains information from the published literature that cites data from refinery as well as pipeline service. The focus has been on the mechanisms of cracking in wet H2S environments. This report differentiates cracking in steels resulting from hydrogen charging from that associated with stress corrosion cracking (SCC) found in amine and carbonate systems that are also affected by the presence of sulfide species. Most importantly, this report highlights and reviews the results from many research studies in addition to several field and plant service investigations. The report is divided into six sections: (1) Hydrogen Permeation in Steel; (2) Sulfide Stress Cracking; (3) Wet H2S Cracking: Refinery Experience; (4) Hydrogen-Induced Cracking: Pipeline Experience; (5) Inhibitors; and (6) Role of H2S in SCC in Amine Solutions. This NACE technical committee report was originally prepared in 1994 by Work Group T-8-16b and Task Group T-8-16 on Cracking in Wet H2S Environments. It was reaffirmed in 2003 and 2013 by Specific Technology Group (STG) 34 on Petroleum Refining and Gas Processing. This technical committee report is published under the auspices of STG 34.

NACE technical committee reports are intended to convey technical information or state-of-the-art knowledge regarding corrosion. In many cases, they discuss specific applications of corrosion mitigation technology, whether considered successful or not. Statements used to convey this information are factual and are provided to the reader as input and guidance for consideration when applying this technology in the future. However, these statements are not intended to be recommendations for general application of this technology, and must not be construed as such.

Terms and Mechanisms Hydrogen Blistering: The formation of subsurface planar cavities, called hydrogen blisters, in a metal resulting from excessive internal hydrogen pressure. Growth of near-surface blisters in low-strength metals usually results in surface bulges. As in sulfide stress cracking (SSC), hydrogen blistering in steel involves the absorption and diffusion of atomic hydrogen produced on the metal surface by the sulfide corrosion process. The development of hydrogen blisters in steels is caused by the accumulation of hydrogen that recombines to form molecular hydrogen at internal sites in the metal. Typical sites for the formation of hydrogen blisters are large nonmetallic inclusions, laminations, or other discontinuities in the steel. This differs from the voids, blisters, and cracking associated with high-temperature hydrogen attack. Hydrogen-Induced Cracking (HIC): Stepwise internal cracks that connect adjacent hydrogen blisters on different planes in the metal, or to the metal surface (also known as stepwise cracking). In steels, the development of internal cracks (sometimes referred to as blister cracks) tends to link with other cracks because of internal pressure resulting from the accumulation of hydrogen. The link-up of these cracks on different planes in steels is often referred to as â&#x20AC;&#x153;stepwise crackingâ&#x20AC;? to characterize the nature of the crack appearance. HIC is commonly found in steels with (a) high impurity levels that have a high density of large planar inclusions and/or (b) regions of anomalous microstructure produced by segregation of impurity and alloying elements in the steel. No externally applied stress is needed for the formation of HIC. Stress Corrosion Cracking (SCC): Cracking of a material produced by the combined action of corrosion and sustained tensile stress (residual or applied). In alkaline environments, SCC in carbon steels sometimes occurs at moderately elevated temperatures because of the presence of various species in the environment such as carbonates, caustics, and amines. In some cases, the presence of cyanide and sulfide species increases the severity of cracking. The cracking is branched and intergranular in nature and typically occurs in non-stress-relieved steels. This form of cracking has often been referred to as carbonate cracking when associated with alkaline sour waters containing carbon dioxide (CO2), and as amine cracking when associated with alkanolamine treating solutions. Stress-Oriented Hydrogen-Induced Cracking (SOHIC): Arrays of cracks in steels, aligned nearly perpendicular to the applied stress, that are formed by the link-up of small HIC cracks in the steel. Tensile stress (residual and/or applied) produces SOHIC. SOHIC is commonly observed in the base metal adjacent to the heat-affected zone (HAZ) of a weld and is oriented in the through-

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NACE International thickness direction. SOHIC is also produced in susceptible steels at other high stress points such as from the tip of mechanical cracks and defects and from the interaction between HIC on different planes in the steel. Sulfide Stress Cracking (SSC): Cracking of a material under the combined action of tensile stress and corrosion in the presence of water and hydrogen sulfide (a form of hydrogen stress cracking). SSC is a form of hydrogen stress cracking involving atomic hydrogen that is produced by the sulfide corrosion process on the metal surface. The atomic hydrogen potentially diffuses into the metal and produces embrittlement. SSC usually occurs more readily in high-strength steels or in hard weld zones of steels.

Section 1: Hydrogen Permeation in Steel 1.1 Summary 1.1.1 Overview of Hydrogen Permeation: Hydrogen-permeation measurements have been employed extensively in the laboratory to characterize the aggressiveness of diverse environments, to evaluate the effectiveness and appropriate concentrations of inhibitors in reducing corrosion and hydrogen absorption, and to evaluate the ability of steels to resist initiation and propagation of hydrogen damage. A significant amount of hydrogen-permeation monitoring of linepipes containing wet sour gas has been undertaken using a variety of devices. Only limited monitoring of pressure vessels (refineries and heavy water plants) has been reported. Hydrogen-permeation monitoring activities are only applicable to those “wet H2S” cracking mechanisms in which absorbed hydrogen atoms play a role, e.g., hydrogen blistering, HIC, SOHIC, and SSC. 1.1.2 Materials Grades and Product Forms: The bulk of the reported hydrogen-permeation work has been performed on API (4) linepipe steels, grades X42 through X75, and on ASTM A 3331 grades 1 and 6 seamless pipe. Work on Japanese (ISIJ), (5) Canadian (CSA), (6) and German (DIN) (7) grades of linepipe steels has also been reported. These linepipes have been fabricated in a variety of ways and include seamless, electric-resistance welded, and submerged-arc welded types. Additional work on high-purity iron, UNS G10100 (AISI 1010), a variety of mild steels, UNS G41300 (AISI 4130), UNS G43400 (AISI 4340), and high-strength low-alloy (HSLA) steels has been reported. Work has been performed on the following ASTM steels: UNS K02700 (A516)2 grade 70 and UNS K02400 (A537)3 class 1 pressure vessel plates, UNS K01803 (A633)4 grade C structural steel, and UNS K12042 (A508)5 class 3 and UNS K03011 (A350)6 grade LF2 forgings. Testing of 2.25 Cr-1 Mo steel plate has also been reported. The steels have been produced by both conventional and more modern techniques such as vacuum degassing, electroslag remelting, calcium treating, and continuous casting. Hydrogen-permeation measurements have been made on steels that have undergone additional refinement, microalloying, and/or special processing procedures. In particular, the effects on hydrogen permeation of lowering carbon, manganese, phosphorus, and sulfur levels and of microalloying have been investigated. 1.1.3 Environments: Electrochemical cathodic charging environments have been used extensively in the development of hydrogen-permeation monitoring devices and in the characterization of steels, e.g., to determine threshold concentrations for initiation of hydrogen damage. A large number of sour environments have been employed in the laboratory, including H2S in pure water, NACE Standard TM0177,7 NACE Standard TM0284,8 ASTM D11419 solutions with varying amounts of acetic acid, NaCl, and sodium acetate. Corrosion inhibitors and other chemicals (e.g., glycol, cyanide, polysulfide) have been added to these environments in some studies. Initial pH values have ranged from 2.6 to 8.8. Most work has been performed in these environments in equilibrium with 0.1 MPa (1 atm) H2S. CO2 and H2S mixtures have been used in some experiments. Test temperatures have ranged from – 10 to 60 °C (14 to 140 °F) with the majority of tests performed at 25 °C (77 °F). Some fullscale tests have been performed at elevated pressures (to 19 MPa [2,700 psi]). A variety of field environments have been monitored. 1.1.4 Types of Hydrogen-Permeation Monitoring Instruments: Devices based on electrochemical principles have been used for the majority of laboratory and field hydrogen-permeation monitoring studies. Limited laboratory and field data have been developed using hydrogen pressure build-up and vacuum devices.

(4)

American Petroleum Institute (API), 1220 L St. NW, Washington, DC 20005. Iron and Steel Institute of Japan (ISIJ), Keidranren Kaikan, Third Floor, 1-9-4 Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan. CSA International (CSA), 178 Rexdale Blvd., Etobicoke, Ontario, M9W 1R3 Canada. (7) Deutches Institut fur Normung (DIN), Burggrafenstrasse 6, D-10787 Berlin, Germany. (5) (6)

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NACE International 1.2 Overview Discussion 1.2.1 Important Trends in the Data 1.2.1.1 Equipment and Techniques for Laboratory Measurements: The majority of laboratory work involving hydrogenpermeation measurements has been performed using electrochemical techniques. The theory behind these techniques and descriptions of the apparatus used have been given particular attention in the literature. A potentiostat, reference electrode, and alkaline solution have often been employed to apply a fixed potential to the monitored steel surface. Emergent hydrogen atoms were oxidized and detected by current flow in the cell. Concentrations of diffusing hydrogen were then calculated through application of electrochemical and diffusion theory. Greater sensitivity and more quantitative results were claimed to be benefits of plating palladium or nickel onto the monitored surface. Sealed-cell devices have become more common for hydrogen-permeation studies. These devices often have solid electrolytes or liquid electrolytes. Claimed advantages include increased life and wider temperature range of operation. Some sealed-cell devices have sacrificial steel membranes that are exposed to the environment of interest, and others have thin palladium foils that are attached with wax to the steel surface to be monitored. A high-temperature device has also been described. Pressure build-up devices have been used in some laboratory studies. Permeating hydrogen has been detected through pressure monitoring or by a technique involving displacement of glycerine or mercury from a measuring cylinder. Vacuum devices have also been employed in laboratory studies. Permeating hydrogen was detected with an ion pump or a mass spectrometer. 1.2.1.2 Equipment and Techniques for Field and Plant Measurements: The types of hydrogen-permeation monitoring devices used in the field until the mid-1980s have been reviewed. Most work using these devices has been performed in the field in connection with refineries. Monitoring of plants producing heavy water by the Geib-Spevack process has occurred. Devices that have been used to monitor permeating hydrogen from vessels in wet, sour environments include vacuum, pressure, and electrochemical probes. The use of electrochemical devices in full-scale tests has also been described. 1.2.1.3 Study of Inhibitors Using Hydrogen-Permeation Measurements: Hydrogen-permeation measurements have been used to investigate the effectiveness of inhibitors and other chemicals in reducing corrosion rates and hydrogen absorption in steel in the laboratory and in the field. Electrochemical techniques were used in most studies, but pressure build-up techniques were employed in addition to electrochemical techniques and vacuum devices. It was found in both laboratory and field studies that there was no accurate correlation between hydrogen permeation and corrosion rates under all conditions. The general consensus has been that hydrogen-permeation measurements have been useful in identifying effective inhibitors for reducing hydrogen absorption and for determining persistency and appropriate dosage. Waterdispersible or water-soluble inhibitors were more effective than polysulfides at reducing corrosion and hydrogen-permeation rates in cyanide-containing fluid catalytic cracking units. In sour laboratory test environments, corrosion and hydrogenpermeation rates were reduced by organic nitrogen compounds with molecular weights greater than 200, by triethylene glycol, by primary amines, and by water-soluble and water-dispersible inhibitors. The importance of selecting an inhibitor that reduced both corrosion and hydrogen-permeation rates was also emphasized. 1.2.1.4 Steel Chemistry and Processing Effects: Hydrogen-permeation rates have been shown to be affected by steel chemistry. Laboratory studies based on testing of linepipe steels have reported that the addition of copper in linepipe carbon steels has reduced hydrogen-permeation rates in mildly acidic H2S-containing environments. The majority of these studies concluded that the hydrogen-permeation rate was reduced with the addition of copper to the steel in an environment of pH 5 and greater. Copper contents from 0.2% to 0.5% were generally required to exhibit the effect. Below pH 5 the solubility of iron sulfide was high, making a copper-enriched iron sulfide layer difficult to form. Copper did not change the threshold concentration (CH0)th to initiate a crack. Also, laboratory studies have reported that greater than 1% cobalt addition in steel reduced hydrogen-permeation rates at pH 3 and greater. 1.2.1.4.1 Others have reported that the addition of chromium sometimes influences hydrogen-permeation rates. Hydrogen absorption is considerably enhanced in high-chromium steels. 1.2.1.4.2 It has also been reported that sulfur content of the steel does not affect hydrogen-permeation rate, but ultra-low-sulfur and shape-controlled steels with calcium (Ca) addition had a lower susceptibility to HIC generally in plates and plate products, but HIC sometimes occurred, less commonly, in seamless tubing. 1.2.1.5 Effects of Environments: Generally, the environmental factors that have affected hydrogen-permeation rates are those factors that influenced the efficiency of hydrogen charging or increased corrosion rates, such as pH, H2S partial pressure, CO2 partial pressure, and cyanide concentration. In acid studies (pH < 7) hydrogen-permeation rates generally increased with lowering of pH. There have been differing laboratory results concerning the effect of H2S and CO2 partial pressure on hydrogen-permeation rates. In some studies, hydrogen-permeation rates increased with increasing H2S partial

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NACE International pressure. Others suggested that hydrogen-permeation rates increased with increasing H2S and CO2 partial pressures, with CO2 having had less influence on hydrogen-permeation rates. Finally, low H2S partial pressure and high CO2 partial pressure increased hydrogen-permeation rates. At high H2S partial pressures, stable sulfide films that reduced high hydrogen-permeation rates formed. In addition, chlorides have been shown to have little effect on hydrogen-permeation rates in acidic solutions. The majority of the literature suggested that pH had the greatest influence on hydrogenpermeation rates when H2S was present. In fluid catalytic cracking systems, at generally alkaline pHs, the presence of cyanides reportedly increased hydrogen-permeation rates as a consequence of complexing of partially protective iron sulfides. In the absence of polysulfide, hydrogen permeation increased with increasing H2S partial pressure and pH in the range of pH 8 to 10. 1.3 Threshold Hydrogen Concentration 1.3.1 Hydrogen-permeation monitoring has been used to determine whether an existing vessel in service could develop hydrogen-related damage. Quantitative measurement of the peak flux of diffusing hydrogen has been used to determine the maximum surface concentration of hydrogen, CHo. The minimum surface threshold concentration of diffusing hydrogen necessary to initiate damage, (CHo)th, has been determined by quantitative hydrogen-permeation measurements in the laboratory. Studies have indicated the importance of using steel from the same heat and in the same condition (cold or hot working, heat treatment) as that used to fabricate the vessel in the determination of (CHo)th. Hydrogen damage has developed when CHo > (CHo)th. Many authors have reported the local threshold concentration of hydrogen necessary to initiate damage in different steels, CHth. Some authors have given (CHo)th values. (CHo)th values have been calculated from CHth values when the location of the damage in the vessel wall was known; e.g., if it was at midwall, then the (CHo)th values were 2 CHth because the point of concentration of hydrogen in the steel was assumed to fall linearly from a value of CHo at the process exposed surface to zero at the external surface. When the (CHo)th value was known, operational steps have been taken to keep the CHo value below that value. The effectiveness of steps taken to lower CHo, such as chemical inhibition, has been monitored by hydrogenpermeation measurements. 1.3.2 Hydrogen-permeation monitoring techniques have been used to identify steels that have low CHo values when exposed to simulated plant conditions in the laboratory. Laboratory work has been used to determine CHo values in simulated field environments and to screen inhibitors for their ability to reduce CHo values. 1.4 Methods of Reducing Hydrogen-Related Damage 1.4.1 Studies in fluid catalytic cracking units have shown that polysulfides and both water-dispersible and water-soluble inhibitors have reduced hydrogen-permeation rates in existing vessels. Laboratory hydrogen-permeation measurements have shown that steels that are very clean (i.e., containing a very low level of oxide and sulfide inclusions) and have reduced levels of carbon, manganese, phosphorus, and especially sulfur, sometimes have high (CHo)th values. Steelmaking processes such as vacuum degassing, electroslag remelting, calcium treatment, and controlled continuous casting have also been used to produce steels with high (CHo)th. 1.5 Limitations in Available Data or Information 1.5.1 The technique(s) used for field hydrogen-permeation measurements have generally produced semi-quantitative results that have been adequate for monitoring the effectiveness of inhibitors. Devices used in the laboratory to monitor the bare or nickel/palladium-plated steel surface have generally produced more quantitative results. Only spot hydrogen-permeation measurements have typically been made in a plant, and some educated guesswork has usually been employed to identify locations where environmental conditions would likely result in the highest hydrogen-permeation rates. Archival samples of the steel of interest have not usually been available for determination of (CHo)th values. Hydrogen-permeation measurements provide no information on anodic cracking mechanisms such as carbonate cracking. 1.5.2 The effects of environmental variables on hydrogen permeation in alkaline pH environments similar to those experienced in refinery operations are not well understood. These variables include temperature, pH and H2S, carbonate, ammonia, and cyanide concentration. 1.6 Observations Based on Existing Data 1.6.1 Hydrogen-permeation monitoring has been considered relevant to the following wet H2S cracking mechanisms: hydrogen blistering, HIC, SOHIC, and SSC.

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NACE International 1.6.2 Very limited monitoring activities have involved pressure vessels in refineries or laboratory environments simulating refining environments. Work performed in the laboratory and on sour gas linepipe has not been considered directly relevant to refineries because of the differences in environmental pH and chemical species present in these applications. 1.6.3 Hydrogen-permeation monitoring devices based on electrochemical techniques have been more quantitative than those based on pressure build-up and vacuum principles. 1.6.4 The development of hydrogen-related damage in susceptible materials has in some instances been minimized by the use of chemical inhibition. Hydrogen-permeation techniques have been utilized to monitor the effectiveness of these chemical treatments. 1.6.5 Steels that have high resistance to hydrogen damage have been identified by permeation measurements. 1.7 Areas of Insufficient Understanding Regarding Wet H2S Cracking 1.7.1 Based on the review of the published literature, the following areas of insufficient understanding regarding wet H2S cracking have been identified: • Quantitative hydrogen-permeation rate measurements have not been made in refineries to identify locations in vessels that have high susceptibility to damage and to determine surface concentrations of diffusing hydrogen. • Threshold surface concentrations of hydrogen to initiate damage in existing steels in refinery vessels have not been determined. • The effects of modifying the service environment or addition of corrosion inhibitors to reduce concentrations of permeating hydrogen to levels well below threshold concentrations for initiation of damage have not been adequately studied.

Bibliography Albright, B.E. “Development and Applications of a New Hydrogen Sensing Instrument.” CORROSION/76, paper no. 76042. Houston, TX: NACE, 1976. Charles, J., L. Cadiou, L. Coudreuse, and G.M. Pressouyre. “Improved Permeation Technique in Order to Understand the Role of Reversible and Irreversible Trapping Effects on HIC Phenomenon.” CORROSION/87, paper no. 87194. Houston, TX: NACE, 1987. Christenson, C., and R.T. Hill. “Full-Scale Test Hydrogen Permeation Measurement and Ultrasonic Imaging of Hydrogen-Induced Cracking in Line.” CORROSION/85, paper no. 85236. Houston, TX: NACE, 1985. Christenson, C., H. Arup, and R.T. Hill. “Corrosion Monitoring in Wet Sour Gas by Use of Hydrogen Permeation Probe.” CORROSION/89, paper no. 89477. Houston, TX: NACE, 1989. DeKreuk, C.W., A. Mackor, and J. Schoonman. “Electrochemical Sensor for the Local Determination of Hydrogen in Metals by Potentiometry.” Dechema Monograph 101 (1985): p. 53. Devanathan, M.A.V., and Z. Stachurski. “The Absorption and Diffusion of Electrolytic Hydrogen in Palladium.” Proceedings of the Royal Society A270, 90 (1962). Du, Y.L, A.M. Fang, and Z. Lu. “Electrochemical Probe for Measuring the Activity of Hydrogen-Induced Cracking for Offshore Engineering Structures.” Proceedings Asian Inspection, Repair, and Maintenance for the Offshore and Marine Industries Conference, paper no. 24, held January 27-29, 1986. Singapore: Chinese Academy of Science, Institute of Corrosion and Protection, 1986, p. 455. French, E.C. “Corrosion and Hydrogen Blistering Control in Sour Water Systems.” CORROSION/76, paper no. 76157. Houston, TX: NACE, 1976. French, E.C., and L.R. Hurst. “Hydrogen Monitoring by the Hydrogen Patch Probe.” Houston, TX: NACE, 1980.

CORROSION/80, paper no. 80047.

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NACE International Galis, M.F, J.L. Dauptain, D. Petelot, and A. Sulmont. “Action of Copper on Hydrogen-Induced Cracking Resistance of Steels: Study of Mechanisms by Hydrogen Permeation Measurements.” CORROSION/87, paper no. 87057. Houston, TX: NACE, 1987. Hay, M.G. “Sour Gas Pipelines—The Need for Hydrogen-Induced Cracking Resistance.” 39th Annual Technical Meeting of Petroleum Society of CIM, held June 12-16, 1988, paper no. 88-39-115. Calgary, Canada: CIM, 1988. Hay, M.G., and D.P. Dutovich. “Electrochemical Monitoring of Carbon Steel Corrosion in Heavy Water Production.” CORROSION/77, paper no. 77181. Houston, TX: NACE, 1977. Hay, M.G., and D.P. Dutovich. “Control of Hydrogen-Induced Cracking in Low-Strength Carbon Steel Exposed to H2S Environments.” First International Conference on Current Solutions to Hydrogen Problems in Steels, held November 1-5, 1982. Washington, D.C.: ASM, 1982. Hay, M.G. “An Electrochemical Device for Monitoring Hydrogen Diffusing Through Steel.” 1982 Canadian Institute of Mining Conference of Metallurgists, H2S Symposium, Edmonton, Canada: CIM, 1982. Herbsleb, G., R.K. Poepperling, and W. Schwenk. “Occurrence and Prevention of Hydrogen-Induced Stepwise Cracking and Stress Corrosion Cracking of Low-Alloy Pipeline Steels.” CORROSION/80, paper no. 80009. Houston, TX: NACE, 1980. Ikeda, A., M. Iino, M. Shimizu, N. Seki, and A. Ejima. “Laboratory Round Robin Tests: The Development of Full Scale Tests and Preliminary Results.” Sour Service in the Oil, Gas, and Petrochemical Industries, held December 11-12, 1985, London, U.K. Ikeda, A., T. Kaneko, and F. Terasaki. “On the Mechanism of Hydrogen-Induced Cracking of Line Pipe Steel in the Wet Hydrogen Sulfide Environment.” Proceedings Second International Conference on Environmental Degradation of Engineering Materials, held September 21-23 1981. Blacksburg, VA: Virginia Polytechnic Institute, 1981, p. 223. Ikeda, A., T. Kaneko, and F. Terasaki. “Influence of Environmental Condition and Metallurgical Factors on Hydrogen-Induced Cracking of Line Pipe Steel.” CORROSION/80, paper no. 80008. Houston, TX: NACE, 1980. Ikeda, A., Y. Morita, F. Terasaki, and M. Takeyama. “On the Hydrogen-Induced Cracking of Line Pipe Steel under Wet Hydrogen Sulfide Environment.” Second International Congress on Hydrogen in Metals, paper no. 4A7, held June 6-11, 1977. Paris, France, 1977. Inagaki, H., M. Tanimura, I. Matsushima, and T. Nishimura. “Effect of Copper on the Hydrogen Induced Cracking of the Pipe Line Steel.” 1976 Iron and Steel Institute of Japan Meeting, Trans. ISIJ 18. Tokyo, Japan: ISIJ, 1978, p. 149. Kaneko, T., A. Ikeda, M. Nakanishi, Y. Sumitomo, and M. Takeyama. “Improvement of Hydrogen Sulfide Cracking Susceptibility in Linepipes for Sour Gas Services.” NACE 1979 Middle East Conference, held April 15-17, 1979. Houston, TX: NACE, 1979. Kato, C., B. Egert, H.J. Grabke, and G. Panzer. “Electrochemical and Surface Analytical Studies on Hydrogen Permeation with Fe-Cu Alloys in Sulfuric Acid with and Without H2S.” Corrosion Science 24, 7 (1984): p. 591. Kawashima, A., K. Hashimoto, and S. Shimodaira. “Hydrogen Electrode Reaction and Hydrogen Embrittlement of Mild Steel in Hydrogen Sulfide Solutions.” Corrosion 32, 8 (1976): p. 321. Kimura, M., T. Hane, T. Kurisu, Y. Nakai, and N. Totsuka. “Effect of Environmental Factors on Hydrogen Permeation in Linepipe Steel.” CORROSION/85, paper no. 85237. Houston, TX: NACE, 1985. Mansfeld, F., S. Jeanjaquet, and D.K. Roe. “Barnacle Electrode Measurement System for Hydrogen in Steels.” Metal Progress 115, 5 (1979): p. 58. Martin, R.L., and E.C. French. “Corrosion Monitoring in Sour Systems Using Electrochemical Hydrogen Patch Probes.” Journal of Petroleum Technology 30, 11 (1978): p. 1566. McBreen, J., W. Beck, and L. Nonis. “A Method of Determination of the Permeation Rate of Hydrogen Through Metal Membranes.” Journal of the Electrochemical Society 113, 11 (1966): p. 1218. NACE Publication 1C184 (latest revision), “Monitoring Internal Corrosion in Oil and Gas Production Operations with Hydrogen Probes.” Houston, TX: NACE.

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NACE International Nakai, Y., T. Emi, O. Haida, and H. Kurahashi. “Development of Steels Resistant to Hydrogen-Induced Cracking in Wet Hydrogen Sulfide Environment.” 1977 Iron and Steel Institute of Japan Meeting, Trans. ISIJ 19, 7. Tokyo, Japan: ISIJ, 1979, p. 401. Nakai, Y., H. Kurahashi, N. Totsuka, and Y. Wesugi. “Effect of Corrosive Environment on Hydrogen-Induced Cracking.” CORROSION/82, paper no. 82132. Houston, TX: NACE, 1982. Peatfield, M., K.A. Eagles, D.J. Fray, and P.H. Schwabe. “Corrosion Monitoring Through a Solid Electrolyte Hydrogen Detector.” Proceedings Asian Inspection, Repair, and Maintenance for the Offshore and Marine Industries Conference, paper no. 26, held January 27-29, 1986. Singapore: Chinese Academy of Science, Institute of Corrosion and Protection, 1986, p. 489. Petelot, D., M.F. Galis, and A. Sulmont. “Corrosive H2S Environments Study by Hydrogen Permeation Measurements— Correlation with HIC and Sulfide Stress Cracking Test Results.” CORROSION/86, paper no. 86165. Houston, TX: NACE, 1986. Radd, F.J., and D.H. Oertle. “Electronic Hydrogen Sensor Studies in the H2S-Air-NaCl-H2S-Fe Corrosion System.” MP 16, 10 (1977): p. 12. Schmitt, G., D. Engels, and H. Schwevers. “Inhibition of Steel Corrosion in Hydrogen Sulfide Saturated Methanol.” 8th European Corrosion Congress, paper no. 61, held November 19-21, 1985. Nice, France: EFC, p. 1. Seki, N., Y. Kobayashi, T. Kotera, T. Nakazawa, and T. Taira. “Evaluation of Environmental Conditions and the Performance of Linepipe Steels Under Wet Sour Gas.” CORROSION/82, paper no. 82131. Houston, TX: NACE, 1982. Shimizu, M., M. Iino, M. Kimura, H. Hakate, and K. Ume. “Hydrogen Entry and Blister Crack Formation in Linepipes Under HighPressure and Dynamic Sour Gas-Bearing Environment.” CORROSION/87, paper no. 8745. Houston, TX: NACE, 1987. Suzuki, K., T. Kouno, T. Murata, and E. Sato. “Study of Inhibitors for Sour Gas Service.” Corrosion 38, 7 (1982): p. 384. Taira, T., T. Hyodo, T. Kobayashi, T. Nakazawa, N. Seki, and K. Ume. “Study on the Evaluation of Environmental Condition of Wet Sour Gas.” CORROSION/83, paper no. 83156. Houston, TX: NACE, 1983. Thomason, W.H. “Corrosion Monitoring with Hydrogen Probes in the Oil Field.” CORROSION/84, paper no. 84237. Houston, TX: NACE, 1984. Tsubakino, H., K. Fukumoto, and K. Tamakawa. “Monitoring Cell of Hydrogen Permeated through Steel at High Temperatures.” Trans. Iron and Steel Institute of Japan 28, 2 (1988): p. 143. Tsubakino, H., and K. Tamakawa. “Online Monitoring of Hydrogen in Steels at Ambient and Elevated Temperatures.” Dechema Monograph 101 (1985): p. 43. Van Gelder, K., and C.J. Kroese. “Effect of Corrosion Inhibitors for Sour Oil and Gas Transport on Hydrogen Uptake by Pipeline Steels.” 6th European Symposium on Corrosion Inhibitors, September 16-20, 1985. Houston, TX: NACE, 1985. Van Gelder, K., C.J. Kroese, and M.J.J. Simon-Thomas. “Hydrogen-Induced Cracking Determination of Maximum Allowed H2S Partial Pressures.” CORROSION/85, paper no. 85235. Houston, TX: NACE, 1985. Vennett, R.M. “Corrosion Monitoring in Oilfield Operations Using a Vacuum Hydrogen Probe.” CORROSION/77, paper no. 77139. Houston, TX: NACE, 1977. ASTM STP 908 (latest revision). “Corrosion Monitoring in Industrial Plants Using Nondestructive Testing and Electrochemical Methods.” West Conshohocken, PA: ASTM. Yoshino, Y. “Metallurgical Influences on the Hydrogen Uptake by Steel in H2S Environment.” Corrosion 39, 11 (1983): p. 435.

Section 2: Sulfide Stress Cracking (SSC) 2.1 Summary 2.1.1 Overview of SSC: Generally, SSC susceptibility increased with increasing strength and hardness of the steels tested and with the hardness of microstructures associated with welds. According to NACE SP047210 weld metals used in wet H2S refinery

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NACE International service have typically been limited to ≤ 200 HB to minimize failures resulting from SSC. Under laboratory conditions, very high tensile loads were necessary to cause cracking in the HAZ of four-point bend specimens in the NACE Standard TM0177 solution. Fracture and fracture modes were dependent on yield strength, hydrogen activity in the steel, especially for highstrength steels (480 MPa [70 ksi] ultimate tensile strength or greater), and the grain boundary-segregated elements. 2.1.2 Materials Grades and Product Forms: Carbon and low-alloy steels in the forms of plate and linepipe comprised the bulk of the materials tested. Continuous cast and control-rolled steels were included. Welds were primarily single-sided submergedarc or shielded-metal arc. The effect of phosphorus segregation in the grain boundaries was investigated in both low-strength carbon steel and in high-strength low-alloy steels. For many years, controversy has existed concerning nickel content of the steel to the extent that NACE MR0175/ISO 1515611 limited nickel content to a maximum of 1%. Several investigations suggested that the effect of nickel is related to the potential resultant microstructure (i.e., retained austenite that transforms to untempered martensite) and its high susceptibility to SSC. Additionally, cold working has generally been found to decrease SSC resistance, particularly in amounts greater than 5% strain. 2.1.3 Environments: Hydrogen-permeation studies were carried out in solutions based on pure water, seawater, various levels of H2S, acetic acid, etc. Most investigators of the SSC and HIC behavior of steels and weldments utilized the NACE Standard TM0177 solution (pH 3, 5% NaCl, 0.5% acetic acid, saturated with H2S) with and without chlorides. The investigation into the effect of phosphorus segregation employed cathodic charging in sulfuric acid with and without arsenous oxide (to promote hydrogen permeation) as well as the NACE Standard TM0177 and TM0284 solutions. In general, these environments have not totally simulated the chemical environment found in many alkaline refinery operations. However, hydrogen fluxes produced in these laboratory environments have been similar to those in actual refinery services. 2.1.4 Types of Test Methods: Other reported test methods for SSC were four-point weld root-bend and side-bend specimens, compact tension specimens, modified fracture mechanics wedge-open-loaded (WOL)-type constant-deflection specimens, and cylindrical tensile specimens in the constant extension rate test (CERT). 2.2 Overview Discussion 2.2.1 Important Trends in the Data: It appears to be universally accepted that the actual crack and crack extension has been caused by the permeation of hydrogen and its diffusion to the crack tip within the steel specimens. In the NACE test solutions, approximately 20 hours have been required to attain the maximum hydrogen permeability. Thereafter, the hydrogen flow through the specimens remained about the same. When SSC did not occur in a NACE test within approximately the first 100 hours, it was generally assumed that any subsequent cracking was no longer purely a function of environmental factors and other variables sometimes have more significance. 2.2.2 Local hard spots, such as have been found in the HAZ of a weld, have not always caused SSC. On the other hand, homogeneous high hardnesses in the HAZ have generally caused SSC. SSC fractures have been either intergranular in highstrength (hardness) steels or quasi-cleavage in lower-strength steels (yield strength ≤ 550 MPa [≤ 80 ksi]). By the same token, it has generally been assumed that grain boundary impurities in high-strength steels, such as those caused by segregation, have increased susceptibility to SSC. Phosphorus (and sulfur) in the steel have often been associated with increased hydrogenrelated damage. 2.3 Wet H2S Refinery Experience 2.3.1 Because refinery equipment has operated for many years when wet H2S and even cyanides were present, hydrogen permeation into steel has been an ever-present concern. Control of residual stresses and weld hardnesses has often been sufficient to prevent SSC. However, through many studies conducted on linepipe steels, it has been found that HIC has been primarily a function of the cleanliness of the steel and therefore has occurred when SSC has not. The use of higher-strength steels has increased the likelihood of SSC. The use of higher-strength and clean steels or steels with restricted hardness has sometimes had a beneficial effect on SSC resistance and has not appeared to increase the likelihood of HIC. 2.4 Methods of Reducing SSC Susceptibility 2.4.1 Steels intended for wet H2S service have shown improved performance as their quality and cleanliness have improved (i.e., reduced sulfur and phosphorus). The literature indicates that steels have also been tested for acceptability in an accelerated test, such as NACE Standard TM0177, to evaluate their resistance to SSC. To minimize SSC, one approach suggested in the literature has been the use of lower-strength steels with carefully controlled weld procedures to reduce hardnesses and bainite/martensite formation in the HAZ. In addition, post-weld heat treatment (PWHT) has been used to temper hard martensitic microstructures and reduce residual stresses. Because many types of weld defects are significant stress raisers, the original fabrication has often been inspected carefully to assure freedom from such defects or flaws. To

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NACE International reduce the hydrogen-permeation rate, inhibitors, water washes, coatings, etc., have been utilized. Hydrogen probes inserted in the equipment have been shown in several studies to have been useful to monitor hydrogen activity. 2.5 Limitations in Available Data and Information 2.5.1 The data and information presented in the papers reviewed have not addressed the relevancy of (accelerated) laboratory test data to service experience in alkaline pH environments. Also, vital statistics and probabilities associated with each of the major variables supposedly having an impact on SSC have not been reported. One cannot easily measure microhardnesses in the actual weld/HAZ. The ability of weld procedure qualification hardness testing to preclude the occurrence of high hardnesses in the production weld and HAZ has not been thoroughly examined. Welding variables are a completely different set of variables that have not had sufficient study. 2.5.2 None of the papers reviewed were based on SSC tests using actual pressure vessels nor did any contain data obtained from a refinery operation or service history. 2.6 Areas of Insufficient Understanding Regarding SSC 2.6.1 Based on the review of the published literature, the following areas of insufficient understanding have been identified: •

The effects of welding and welding variables, particularly the effects on the HAZ and parent material adjacent to the HAZ.

•

Service correlations with laboratory test data.

•

The effects associated with repair welding and/or grinding on susceptibility to SSC.

•

The ability of coatings to prevent in-service SSC, including the effect of pinholes or deterioration in coatings.

Bibliography Christensen, C.J., and R.T. Hill. “Characterizing Acceptable Weld Heat-Affected-Zone Hardness in Low-Alloy Steels.” CORROSION/85, paper no. 85241. Houston, TX: NACE, 1985. Chu, W., C. Haiao, S. Li, and J. Tien. “Mechanism of Stress Corrosion Cracking of Steels in H2S.” Corrosion 36, 9 (1980): p. 475. Dayal, R.K., and H.J. Grabke. “Hydrogen-Induced Stress Corrosion Cracking in Low- and High-Strength Ferritic Steels of Different Phosphorus Content in Acid Media.” Werkstoffe und Korrosion (Materials and Corrosion) 38, 8 (1987): p. 409. Dunlop, A.K. “Stress Corrosion Cracking of Low-Strength, Low-Alloy Nickel Steels in Sulfide Environments.” CORROSION/77, paper no. 77108. Houston, TX: NACE, 1977. Ikeda, A., Y. Ando, and T. Kaneko. “On the Evaluation Method of Sulfide Stress Cracking Susceptibility of Carbon and Low-Alloy Steels.” Corrosion Science 27, 10-11 (1987): p. 1099. Omar, A.A., W.K. Boyd, and R.D. Kane. “Factors Affecting the Sulfide Stress Cracking Resistance of Steel Weldment.” The International Corrosion Forum, held April 6-10, 1981. Houston, TX: NACE, 1981. Petelot, D., M.F. Galis, and A. Sulmont. “Corrosion H2S Environments Study by Hydrogen Permeation Measurements— Correlation with HIC and Sulfide Stress Cracking Test Result.” CORROSION/86, paper no. 86165. Houston, TX: NACE, 1986. Pircher, H., and G. Sussek. “Testing the Resistance of Welds in Low-Alloy Steels to Hydrogen Induced Stress Corrosion Cracking.” Corrosion Science 27, 10-11 (1983): p. 1183. Turn, J.C. Jr., C.A. Troianos, and B.E. Wilde. “On the Sulfide Stress Cracking of Line Pipe Steels.” Corrosion 39, 10 (1983): p. 364. Ume, K., T. Hyodo, Y. Kobayashi, and T. Taira. “Initiation and Propagation Morphology of Sulfide Stress Corrosion Cracking at Welds on Linepipe Steels.” CORROSION/85, paper no. 85240. Houston, TX: NACE, 1985.

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NACE International Watkins, M., M.F. Bluem, and J.B. Greer. “Fractorgraphy of Sulfide Stress Cracking.” CORROSION/75, paper no. 75098. Houston, TX: NACE, 1975. Wilde, B.E., and M.J. Doyle. “A Comparison Between Threshold Stress and ‘Crack Initiation' Stress Intensity for Sulfide Stress Corrosion Cracking.” Corrosion 35, 6 (1979): p. 273. Yamane, Y., M. Kimura, T. Kurisu, K. Motoda, Y. Nakai, and N. Totsuka. “Effect of Ni on Sulfide Stress Corrosion Cracking in Low-Alloy Steels.” CORROSION/86, paper no. 86167. Houston, TX: NACE, 1986.

Section 3: Wet H2S Cracking—Refinery Experience 3.1 Summary 3.1.1 Inspection of carbon steel vessels by the wet fluorescent magnetic particle test (WFMT) has disclosed many cracks that were not previously detectable by other techniques. The cracks were detected in equipment exposed to wet H2S during operation. However, other techniques, such as ultrasonic testing (UT), have been used to detect subsurface (internal) cracks. The literature approaches the subject matter from four different directions: (1) extent and severity of the cracking damage found during refinery inspections; (2) laboratory testing used to identify cracking mechanisms and susceptible steels; (3) role played by hard weldments; and (4) metallurgy and refinery process changes used to minimize cracking damage. 3.1.2 Inspection Results: The literature provided detailed information on actual refinery experiences utilizing WFMT and experience gained from construction, inspection, and repair of LPG (liquid petroleum gas) spheres. The references provided details of results from inspection and repair of 189 pressure vessels in various refinery units and an update of this work along with the results of an industry-wide survey. Crack growth in one particular vessel over a 10 year period was documented. Discussions concerning the different kinds of cracking that have occurred along with the locations that have been most susceptible were presented. Steels and conditions that have been most likely to present problems were also discussed. 3.1.3 Cracking Mechanisms: The results of a four year research program sponsored by NACE International during the early 1950s were described. This program concentrated on embrittlement and cracking, hydrogen absorption, hydrogen permeability, and delayed fracture phenomena in iron-nickel alloys used in oil production. The literature established the role of H2S in cracking mechanisms and evaluated the susceptibility of various steels to SOHIC using NACE Standards TM0284 and TM0177, among others. It was shown that varying test conditions in NACE Standard TM0284 increased the test sensitivity to detect the cracking tendency of test specimens under laboratory conditions. 3.1.4 Role of Hard Welds: A number of studies investigated the role played by hard weldments and included the effect of untempered martensite on H2S cracking susceptibility. H2S cracking seen in many refinery vessels during the early 1970s was described. The studies found that cracking occurred primarily at welds with weld metal hardness values above 225 HB. An extensive test program that evaluated the effects of welding parameters and procedures on weld hardness and H2S cracking susceptibility was described. The literature also reviewed data showing the relationship between H2S content of aqueous solutions and either maximum permissible HAZ hardness or cracking threshold stress. 3.1.5 Metallurgy and Refinery Process Changes: General methods to prevent hydrogen damage and define the extent and severity of damage seen in different refining processes have been suggested in several papers. The studies also provided laboratory data that served as a basis for process changes to minimize damage. Details of a water/air injection scheme to convert cyanides to thiocyanates were described. Recommendations were made for the use of ammonium polysulfide to control corrosion and hydrogen blistering in refinery equipment. Significant environmental factors affecting wet H2S corrosion and hydrogen blistering were discussed. 3.2 Discussion 3.2.1 Inspection Results: Hydrogen absorption by carbon steels has been associated with the following problems in refinery service: •

SSC in high-strength or high-hardness steels.

•

Blister formation or HIC in steels originating at nonmetallic inclusions and laminations (hydrogen blistering).

•

HIC producing "stepwise" cracks in steels.

•

Loss of ductility under a slow tensile loading (hydrogen embrittlement).

•

Through-wall propagation of cracks by a HIC mechanism influenced by an applied stress (SOHIC).

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NACE International 3.2.1.1 The most likely location for cracking has been in the region of the HAZ next to welds and in the weld deposits. Metallographic examination indicated that many cracks initiated as SSC in small hard areas in the HAZ. This cracking usually terminated when the flaw reached the softer base metal. At that point, further crack extension has sometimes occurred in susceptible steels as a result of HIC or SOHIC. Detailed measurements indicated that cracks have sometimes occurred in areas where even the weld metal hardness criteria of NACE SP0472 have been met. 3.2.1.2 Inspection priorities for various refinery equipment have been categorized. Refinery service containing H2S and cyanide along with alkaline pH has typically represented the most severe conditions for hydrogen-related damage. 3.2.1.3 Most authors agree that PWHT has reduced, but not totally eliminated, the cracking tendency. A low-temperature hydrogen-outgassing procedure that has been used to reduce the amount of hydrogen retained in the metal after welding of higher-strength (hardness) grades of steel was also described. 3.2.1.4 Removing and repairing the indicated cracks has at times been very frustrating. Inspection subsequent to weld repair sometimes revealed additional cracks after the repair was completed. Although the problem was not fully understood, it was believed that the new cracks were actually very tight cracks that opened up as a result of the heat of welding or PWHT. A low-temperature hydrogen-outgassing procedure has been used before attempting weld repairs. 3.2.1.5 It has been observed that wet H2S cracking tendency increased with increasing hardness and with increasing steel strength. The following cracking tendencies are listed in Table 1:

Table 1 Wet H2S Cracking Tendencies Tensile Strength MPa (ksi)

Potential

Mechanism

380 to 520 (55 to 75)

Low

HIC

410 to 550 (60 to 80)

Low

HIC

(A)

Possible

SSC, HIC, HE

(A)

Possible

SSC, HIC, HE

Likely

SSC, HE

Very Likely

SSC, HE

480 to 620 (70 to 90) 520 to 630 (75 to 92)

(A)

610 to 730 (88 to 106)

(A)

790 to 930 (115 to 135) (A)

Careful welding procedures have generally been employed to minimize hydrogen cracking during fabrication.

3.2.1.6 The data given in Table 1 account for forms of cracking other than SOHIC and sometimes actually refer to SSC and hydrogen embrittlement (HE) weld cracking from fabrication. 3.2.2 Cracking Mechanisms and Laboratory Testing: Even the earliest studies concluded that the basic cause of failure in sulfide-containing environments was associated with hydrogen absorption. While other factors sometimes have had a contributing effect, internal stress, applied stress, and hydrogen content played the most important role. Later studies determined that H2S not only promoted corrosion but also facilitated atomic hydrogen entry into steel by poisoning the recombination reaction to molecular hydrogen. Most importantly, they also showed that H2S was not directly involved in the cracking mechanism. 3.2.2.1 The NACE Standard TM0177 solution has been shown to be more aggressive than other commonly used test solutions for evaluating the susceptibility of various steels to HIC. SOHIC has occurred in ASTM A28512 steels at stresses above 30% of the yield strength. ASTM A516 steels (including several HIC-resistant versions) have experienced SOHIC at stresses above 50% of the yield strength. Areas of stress concentration have been more susceptible to SOHIC than any other areas. It was concluded, however, that NACE Standard TM0284 with NACE Standard TM0177 solution has been a useful qualification test for steels (including the low-sulfur and shape-controlled HIC-resistant steels) intended to resist both HIC and SOHIC in severe wet H2S service. A commonly used acceptance criterion for some applications has been a CLR (crack length ratio) value below 15%. 3.2.2.2 The literature provided the following description of the HIC mechanism. The corrosion caused by wet H2S provides a source of hydrogen atoms that diffuse through the metal. The diffusing atoms are trapped at the interfaces between the matrix and nonmetallic inclusions. When atomic hydrogen accumulates in the steel or at inclusion interfaces and forms molecular hydrogen, separation occurs because of the pressure build-up, and a crack is formed. Ductile ligament tearing occurs between coplanar cracks and is driven by the internal gas pressure. The result is a crack with a

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NACE International "stepwise" appearance. When HIC occurs in an area of stress concentration, the cracking tends to propagate through the thickness of the metal and is referred to as SOHIC. This is characterized by a crack growing by the HIC mechanism in a direction nearly normal to the applied stress. 3.2.2.3 The inclusions that cause HIC have usually been highly oriented in the direction the steel plate was rolled during manufacture. The orientation has generally resulted from the elongation of the sulfide inclusions during hot rolling. The HIC resistance of a sample has been evaluated using the results of the NACE Standard TM0284 test. However, the orientation of the test specimen has been critical and longer periods of exposure to the test solution have sometimes been used to give a truly valid test. 3.2.3 Role of Hard Welds 3.2.3.1 Early studies recognized the role of untempered martensite. They identified three zones of cracking susceptibility in wet H2S environments: (1) below 35% martensite, no cracking occurred regardless of stress level. Hardness values for these steels were below 33 HRC; (2) between 35% and 75% martensite, cracking occurred if a certain applied stress was exceeded. That stress decreased as the percentage of martensite increased, but typically ranged from 240 MPa (35 ksi) (50% of yield strength) with 35% martensite steel to 170 MPa (25 ksi) (20% of yield strength) with 75% martensite steel; (3) above 75% martensite, any applied stress caused cracking. Hardness values for these steels exceeded 48 HRC. 3.2.3.2 It was found that some vessel failures were caused by hydrogen embrittlement and cracking of hard weld deposits, resulting, in one case, in an 11 in (280 mm) crack and a major spill. The process environment included wet H2S. The cracks were transverse to a submerged arc welded seam and were contained entirely within hard weld metal. Soft shielded metal arc welds did not crack. The welds had not received PWHT and were assumed to contain high residual stresses. Hardness values of weld metal ranged from 200 to 285 HB and higher because of high manganese and/or silicon contents. A hardness limit of 235 HB did not guarantee, however, that cracking would not occur. The conclusion was reached that cracking was the result of three interrelated factors: (1) high hardness of the weld microstructure; (2) high stresses; and (3) a corrosive environment that introduced hydrogen into the steel. It was indicated that fabricators should make an effort to match weld properties to base metal properties. Unfortunately, this aspect has not been addressed by the relevant codes. 3.2.3.3 Nearly identical conclusions were reached by other studies that emphasized that any welding procedures that produced high-hardness welds were suspect. These procedures included submerged-arc welding using high-manganese wire-flux combinations and gas metal arc welding (GMAW) with C-0.5% Mo filler metal wire. PWHT minimized welding stresses and tempered the martensite present. These studies recommended a maximum hardness of 225 HB. 3.2.3.4 Studies have determined that some bonded fluxes at high voltages produced welds with excessively high manganese and silicon contents. These had macroscopic weld metal hardness values near 240 HB and readily cracked when exposed to aqueous H2S. As a rule, welds produced with specified consumables over-matched the hardness of a 480 MPa (70 ksi) steel both in the as-welded and PWHT conditions. This overmatch, in conjunction with residual weld stresses, made the welds susceptible to cracking by aqueous H2S. Based on the results of laboratory tests, a maximum macroscopic weld metal hardness of 200 HB minimized the likelihood of cracking caused by SSC. 3.2.3.5 The effect of small hard patches of martensite in welds made with certain bonded fluxes was also studied. These patches were shown to initiate cracking in hard welds and welds of borderline average hardness (191 to 215 HB). Subsurface hard zones presented a greater problem than surface hard patches, as far as crack propagation was concerned. Once a crack was initiated, hydrogen pressure build-up became the driving force for crack propagation. It was found that PWHT at 620 Â°C (1150 Â°F) for one hour was insufficient for crack-initiation prevention at hard patches, but sometimes limited crack propagation by reducing residual stresses. 3.2.3.6 The effect of different steelsâ&#x20AC;&#x2122; hardness values on cracking tendency in wet H2S environments (among others) was discussed. Maximum hardness values of 22 HRC according to NACE MR0175/ISO 15156 for both welded and nonwelded steels in oilfield production service and 200 HB according to NACE SP0472 for weld metal in refinery service have become generally accepted criteria for avoiding SSC. It was also noted that failures have been reported in both parent and weld metal below these hardness levels when the microstructure was susceptible to HIC and SOHIC. Data have been presented that suggest hardness values greater than 22 HRC (248 HV) could be tolerated at H2S contents below the atmospheric-pressure saturation level (about 3,000 ppm). For example, at 100 ppm H2S, a maximum hardness of 280 HV is sometimes resistant to SSC. 3.2.4 Metallurgy and Refinery Process Changes: Many studies described specific refinery practices in regard to alloy upgrading and process changes for reduced hydrogen uptake in steel vessels. Some studies recommended alloying, protective

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NACE International cladding, use of steels with improved homogeneity, and use of certain inhibitors. The following factors were found to cause hydrogen-related damage: •

Presence of a free water phase.

•

Presence of H2S. There was no correlation, however, between H2S concentration and damage severity.

•

Either acidic or alkaline conditions.

•

Presence of a hydrogen-penetration promoter such as cyanides.

•

Existence of a critical balance among water-soluble compounds. 3.2.4.1 It was noted in the literature that large quantities of water have been used for water washing. The damagecausing agents have typically followed the light hydrocarbons in a given plant. Even low corrosion rates have been found to be sufficient to cause hydrogen-related damage. Vapor areas have generally shown more severe attack than areas exposed to aqueous condensate. Inspection has been found to be important because steel can be severely fissured (cracked) even in the absence of hydrogen blisters. Detailed guidelines for measuring hydrogen activity in various fluidized catalytic cracking unit (FCCU) process streams and implementing protective measures have been given. The latter included early removal of H2S by contacting with diethanolamine (DEA), extensive water washing of the main fractionator overhead system and compressed-vapor section, and injection of polysulfide solution or organic corrosion inhibitors. Other recommendations included the installation of protective liners (concrete, UNS S41000 [AISI 410] stainless steel, UNS S30400 [AISI 304] or UNS 31600 [316 stainless steel], and UNS N04400), injection of corrosion inhibitor, water washing, and air injection. Details on inhibitor addition rates and relative effectiveness in removing or converting cyanides were given. The literature discussed in great detail the use of hydrogen probes for monitoring hydrogen activity. Various schemes for removing corrosive constituents by water washing were outlined and analytical data that permit an assessment of their effectiveness were provided. In many instances, hydrogen blistering was accompanied by hydrogen embrittlement and SOHIC.

3.3 Observations Based on Existing Data: The literature indicated that some refinery equipment exposed to wet H2S has experienced cracking problems, which varied substantially in severity. To detect such cracking problems, existing equipment has generally been inspected periodically in recent years. The sensitive WFMT inspection has been shown in many cases to accurately detect surface-connected defects. This technique has sometimes been used in combination with UT to evaluate both surface and subsurface cracks. 3.3.1 Studies presented in the published literature indicated that prior to repair welding, outgassing of hydrogen by heating has generally been helpful in reducing problems associated with hydrogen in the steel during welding. Additionally, PWHT has been utilized to reduce residual stress and lower hardness in some materials and weldments and thereby minimize the likelihood of SSC. However, the literature has not indicated substantial benefit of PWHT with regard to HIC or SOHIC. 3.3.2 The published literature indicated that problems associated with cracking in H2S service have been minimized through careful material selection and testing. These studies indicated that the HIC resistance of candidate materials has been evaluated and compared using NACE Standard TM0284. SSC resistance was evaluated using NACE Standard TM0177. For more aggressive wet H2S service applications, the NACE Standard TM0284 test has been made more discriminating through the use of the NACE Standard TM0177 test solution. In some cases, in areas of very severe hydrogen charging where cracking of steels has been likely, alternate materials options such as cladding and stainless steel have been used. Process changes have been implemented in an attempt to reduce the aggressiveness of various refinery streams. These process changes have included H2S removal, water washing, polysulfide or air injection, and use of organic corrosion inhibitors.

Bibliography Baldy, M.F., and R.C. Bowden Jr. “The Effect of Martensite on Sulfide Stress Corrosion Cracking.” Corrosion 11, 10 (1955): p. 19. Bartz, M.H., and C.E. Rawlins. “Effects of Hydrogen Generated by Steel.” Corrosion 4, 5 (1948): p. 187. Berkowitz, B.J., and F.H. Heubaum. “Role of Hydrogen in Sulfide Stress Cracking of Low-Alloy Steels.” Corrosion 40, 5 (1984): p. 240.

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NACE International Berkowitz, B.J., and H.H. Horowitz. “The Role of H2S in the Corrosion and Hydrogen Embrittlement of Steel.” Journal of the Electrochemical Society 129, 3 (1982): p. 468. Buchheim, G.M. “Ways to Deal with Wet H2S Cracking Revealed by Study.” Oil and Gas Journal 88, 28 (1990): p. 92. Bulla, J.T., and J.T. Chikos. “Case History—FCCU Absorber Deethanizer Tower Hydrogen Blistering and Stepwise Cracking.” CORROSION/89, paper no. 89264. Houston, TX: NACE, 1989. Cantwell, J.E. “LPG Storage Vessel Cracking Experience.” CORROSION/88, paper no. 88157. Houston, TX: NACE, 1988. Effinger, R.T., M.L. Renquist, A. Wachter, and J.G. Wilson. “Hydrogen Attack of Steel in Refinery Equipment.” Proc. API, 31 (HI). Washington, DC: API, 1951, p. 107. Ehmke, E.F. “Hydrogen Diffusion Corrosion Problems in a Fluid Catalytic Cracker and Gas Plant.” Corrosion 16, 5 (1960): p. 116. Ehmke, E.F. “Use of Ammonium Polysulfide to Stop Corrosion and Hydrogen Blistering.” CORROSION/81, paper no. 81059. Houston, TX: NACE, 1981. Gooch, T.G. “Hardness and Stress Corrosion Cracking of Ferritic Steel.” The Welding Institute Research Bulletin 23, 8 (1982): p. 241. Hildebrand, E.L. “Aqueous Phase H2S Cracking of Hard Carbon Steel Weldments—A Case History.” Proc. API, Vol. 50 (III). Washington, DC: API, 1970, p. 593. Kane, R.D., S.M Wilhelm, and J.W. Oldfield. “Review of Hydrogen-Induced Cracking of Steels in Wet H2S Refinery Service.” Proceedings International Conference on Interaction of Steels with Hydrogen in Petroleum Industry. New York, NY: Materials Properties Council, 1989. King, G.R. “How to Reduce Hydrogen Attack.” Petroleum Refiner 35, 1 (1956): p. 124. Kotecki, D.J., and D.G. Howden. “Wet Sulfide Cracking of Submerged-Arc Weldments.” Proc. API, Vol. 52 (III). Washington, DC: API, 1972, p. 631. Kotecki, D.J., and D.G. Howden. “Weld Cracking in a Wet Sulfide Environment.” Proc. API, Vol. 52 (III). Washington, DC: API, p. 573. Merrick, R.D. “Refinery Experiences with Cracking in Wet H2S Environments.” MP 27, 1 (1988): p. 30. Merrick, R.D., and M.L. Bullen. “Prevention of Cracking in Wet H2S Environments.” CORROSION/89, paper no. 89269. Houston, TX: NACE, 1989. Neill, W.J. Jr. “Prevention of In-Service Cracking of Carbon Steel Welds in Corrosive Environments.” MP 10, 8 (1971): p. 33. Neumaier, B.W., and C.M. Schillmoller. “Deterrence of Hydrogen Blistering at a Fluid Catalytic Cracking Unit.” Proc. API Vol. 35 (III). Washington, DC: API, 1955, p. 92. Schuets, A.E., and W.D. Robertson. “Hydrogen Absorption, Embrittlement, and Fracture of Steel—A Report on Sponsored Research on Hydrogen Sulfide Stress Corrosion Cracking.” Corrosion 13, 7 (1957): p. 437t. Weng, Y., and B.E. Wilde. “Effect of Test Specimen Orientation on the Hydrogen-Induced Cracking Rating of Linepipe Steel in the NACE TM0284 Test.” MP 27, 3 (1988): p. 31.

Section 4: Hydrogen-Induced Cracking—Pipeline Experience 4.1 Summary 4.1.1 Introduction: Most of the HIC literature available to date has reported information for pipeline applications. HIC phenomena have been well documented since 1948, when a description of a linepipe and vessel blistering problem was first published. However, the first actual description of HIC was circa 1840. The mechanism for HIC has become well understood,

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NACE International and highly resistant linepipe steels that are capable of withstanding very severe service conditions have been readily purchased and installed. 4.1.2 Material: Early failures were reported in steel pipe and the steel industry progressed to the production of fully killed steel for sour gas transmission purposes. Further developments followed on control-rolled steels. As environments moved to more aggressive (higher H2S and CO2, low pH) conditions, lower-sulfur, calcium-treated steels were developed. The typical steel used was API Spec 5L,13 up to grade X65. With the advent of accelerated-cooled steels, X65 has become a common grade used for large-diameter pipe. 4.1.2.1 Larger-diameter linepipe has generally been longitudinally submerged arc welded and mechanically expanded. Some spirally welded pipe has been used, but as the wall thickness requirements of the industry have increased, the supply of spiral pipe has decreased. 4.1.2.2 Seamless pipe followed a similar trend and has generally been supplied in accordance with the API Spec 5L. Grades X52 and X60 have been commonly used; however, use of grades X65 and X70 has recently become more common. 4.1.3 Environments: Pipeline steels have been evaluated in laboratory tests in a very wide range of conditions: • H2S: 100 to 3,000 ppm (dissolved in aqueous solution) • pH: 2.8 to 8.0 • CO2: 0 to 80 percent by volume (gas phase) 4.1.3.1

Tests with buffered solutions, inhibitors, and even glycols (drying agents) have been performed.

4.1.3.2 It has been recognized that the generally used test temperature of 25 °C (77 °F) was the most convenient for the evaluation of HIC. However, maximum susceptibility to HIC has been found at slightly elevated temperatures (see Paragraph 4.2.2.1). There has been considerable difference of opinion regarding the optimum pH levels for tests. It has been widely agreed that good performance of a steel under pH test levels approaching 3 (e.g., NACE Standard TM0177 test solution) corresponded to good performance in the vast majority of field conditions. It has also been observed that the higher the level of H2S, the higher the hydrogen-permeation rate. When the field hydrogen-permeation rates were known, the test parameters have sometimes been adjusted to more nearly duplicate the conditions. 4.1.4 Test Methods 4.1.4.1 The most commonly used tests have been the NACE Standard TM0284 test with either the pH 5.2 solution specified therein, or the more severe pH 2.7 solution specified in NACE Standard TM0177. 4.1.4.2 Full-scale combined HIC/SSC tests and full-section bent-beam tests have been used, especially for testing the effects of applied stress or the susceptibility to SOHIC of welds, HAZ, and parent metals. 4.2 Discussion 4.2.1 Effects of Major Parameters: Studies have shown that low levels of sulfur (i.e., ≤ 0.005%) have reduced sulfide inclusions that initiate HIC in pipeline steels (see Paragraphs 3.2.2.2 and 3.2.2.3). These low-sulfur steels were also low in oxygen and were calcium-treated to a given ratio. The addition of Cu to the steel has been found to be beneficial for pH ≥ 5.0. No benefit has been observed below pH 5. Normalizing or quenching and tempering heat treatments have been found to be beneficial in reducing HIC by removing the hot-rolled microstructure in the as-processed material. 4.2.1.1 Segregation of elements such as manganese, phosphorus, and boron has been shown to be undesirable. Segregation has been shown to assist in the formation of anomalous microstructures such as bainite, martensite, etc., which can also initiate HIC and/or SSC. 4.2.1.2 Studies have shown that the combination of pH and H2S content in the environment was of paramount importance, because that combination dictated the hydrogen-permeation rate, which in turn has been related to the cracking of steels in wet H2S environments. Measurements of the hydrogen flux and Cth, the hydrogen threshold level for cracking, have been increasingly performed to quantify HIC resistance of steels.

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NACE International 4.2.2 Significance of H2S Regarding Refinery Operations: Some studies have suggested that pipeline experience is sometimes directly relevant to refinery practice in some aspects. The major differences, however, have been the wall thickness, types of the steels used, steel processing and fabrication, and service environments. 4.2.2.1 Whether the H2S-containing service environment was in a pipeline or in a refinery vessel, the observed hydrogenrelated cracking mechanism has generally been the same (i.e., hydrogen pressure build-up at internal sites in the steel [e.g., hydrogen blistering, HIC, and SOHIC]). At moderately elevated temperatures (60 to 120 °C [140 to 248 °F]), susceptibility to SSC generally has been observed to decrease. However, in some cases, susceptibility to HIC has been observed to reach a maximum at slightly elevated temperatures. 4.2.2.2

Some factors in refineries that pipeline experience has not addressed include:

• Mixed metal situations (i.e., galvanic corrosion that has accelerated corrosion and hydrogen charging of steels). • Stress regimes and patterns, which have generally been simple in pipelines but not in refinery vessels. • Environments: Chemistry and physical parameters have changed continuously through refineries because of changes in crude and upsets, and this has not generally been the case in pipelines. Generally, refinery operations have included many alkaline pH (≥ 8) environments containing H2S and possibly cyanide, whereas pipeline experience has usually been limited to acidic conditions. • Cyclic loading and thermal cycling that have potentially assisted crack growth in plant equipment. • There have not been many different basic forms of welds and procedures for pipelines (i.e., longitudinal welds, girth welds, repair welds, and fittings), whereas hundreds of different configurations and procedures have been used in refineries. • Refineries have been subject to different codes (e.g., refineries—ASME (8) Boiler and Pressure Vessel Code,14 ANSI (9)/ASME Code for Pressure Piping, B31,15 Section B31.3; pipelines—Sections B31.4 and B31.8). • Aboveground equipment in refineries has generally provided better access for inspection than buried pipelines. In refinery operations it has been common to monitor corrosion and cracking on-stream by nondestructive examination (NDE). The accessibility of refinery equipment has also provided for greater ease of NDE and cracking monitoring and for internal visual and enhanced inspection methods, such as WFMT, during shutdown periods. 4.3 Limitations in Available Data: The published literature on pipeline experience has not provided information regarding the performance of higher-carbon, thick-walled plate steels, such as ASTM A516 and A285, which have been commonly used in refinery operations. It has been well established that a banded microstructure found in plate steels can contain anomalous phases that are susceptible to HIC. However, the amount of published data available on HIC testing of such materials and service experience has been limited in comparison with that found for pipeline steels. Some data known to exist have not appeared in the published literature. 4.3.1 In general, pipeline experience stemmed from sour operations that did not have significant levels of other chemical species, such as cyanide, polysulfide, and ammonia compounds. In refinery operations, the presence of some of these other species has sometimes produced conditions of hydrogen charging at alkaline pH’s that differ from those in pipeline operations. In some circumstances, other species have been beneficial in reducing the hydrogen-permeation rate. 4.3.2 Specific refinery operating conditions have not been used in many published studies; therefore, the selection of the correct test procedures has been difficult. 4.4 Observations Based on Existing Data: There was a wealth of experience in the published literature regarding the operation of sour pipelines. Many of the major steel companies and oil companies have contributed to the understanding of the cracking mechanisms experienced. HIC-resistant steels that involved the use of low sulfur, calcium treatments, and normalizing have been readily available for use in sour pipelines. These have just recently been applied to steels used by the refinery industry.

(8) (9)

ASME International (ASME), Three Park Ave., New York, NY 10016-5990. American National Standards Institute (ANSI), 11 West 42nd St., New York, NY 10036.

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NACE International 4.5 Areas of Insufficient Understanding Regarding Wet H2S Cracking 4.5.1 SOHIC has been reported in several failures but there has been only limited information available on this type of cracking. This form of cracking has at times appeared as a combination of SSC initiation and HIC propagation. 4.5.2 The influence of cyanide and of environmental variables in the process environment have not been well defined in the published literature.

Bibliography Biefer, G.B. “The Stepwise Cracking of Linepipe Steels in Sour Environments.” Physical Metallurgy Research Laboratories, Canada Centre for Mineral and Energy Technology (CAMNET). Ottawa, Ontario, Canada: Department of Energy, Mines, and Resources, 1981. Brown, A., and C.L. Jones. “Hydrogen-Induced Cracking in Pipeline Steels.” CORROSION/83, paper no. 83155. Houston, TX: NACE, 1983. Bruno, T.V., and R.T. Hill. “Stepwise Cracking of Pipeline Steels—A Review of the Work of Task Group T-1F-20.” CORROSION/80, paper no. 80006. Houston, TX: NACE, 1980. Charles, V., V. Lemoine, G.M. Pressouyre, and L. Cadiou. “Metallurgical Parameters Governing HIC and Sulfide Stress Cracking Resistance of Low-Alloy Steels.” CORROSION/86, paper no. 86164. Houston, TX: NACE, 1986. Galis, M.F.J., and G.C. Guntz. “Study of Metallurgical Parameters Influencing the Behavior of Linepipes in H2S Medium.” CORROSION/88, paper no. 88195. Houston, TX: NACE, 1988. Herbsleb, G.R., K. Popperling, and W. Schenk. “Occurrence and Prevention of Hydrogen-Induced Stepwise Cracking and Stress Corrosion Cracking of Low-Alloy Pipeline Steels.” CORROSION/80, paper no. 80009. Houston, TX: NACE, 1980. Ikeda, A., T. Kaneko, and F. Terasaki. “Influence of Environmental Condition and Metallurgical Factors on Hydrogen-Induced Cracking of Line Pipe Steel.” CORROSION/80, paper no. 8. Houston, TX: NACE, 1980. Ikeda, A., Y. Nara, F. Terasaki, M. Takeyama, and T. Takeuchi. “Hydrogen-Induced Cracking Susceptibility of Various Steel Line Pipes in the Wet H2S Environment.” CORROSION/78, paper no. 78043. Houston, TX: NACE, 1978. Iino, M. “Linepipe Steels for Use in Wet Environments Containing H2S.” Key Engineering Materials 1, 1 (1982): p. 1. Moore, E.M., and J.J. Warga. “Factors Influencing the Hydrogen Cracking Sensitivity of Pipeline Steels.” MP 15, 6 (1976): p. 17. Nakai, Y., H. Kurahashi, N. Totsuka, and Y. Wesugi. “Effect of Corrosive Environment on Hydrogen-Induced Cracking.” CORROSION/82, paper no. 82132. Houston, TX: NACE, 1982. Renault, J.J., F. Braouezec, J.L. Corneuy, and G. Guntz. “Susceptibility of Seamless Line Pipe to Hydrogen-Induced Cracking.” CORROSION/85, paper no. 85238. Houston, TX: NACE, 1985. Schmidt, G., W. Bruckhoff, and L. Sobbe. “Corrosion and Hydrogen-Induced Cracking of Pipeline Steel in Moist Triethylene Glycol Diluted with Liquid Hydrogen Sulfide.” Corrosion Science 27, 10-11 (1987): p. 1071. Seki, N., Y. Kobayashi, T. Kotera, and T. Taira. “Evaluation of Environmental Conditions and the Performance of Line Pipe Steels under Wet Sour Gas.” CORROSION/82, paper no. 82131. Houston, TX: NACE, 1982. Taira, T., and Y. Kobayashi. “Full-Size Sulfide Stress Cracking Test Results of Line Pipe Under Wet Sour Gas Environments.” CORROSION/81, paper no. 81183. Houston, TX: NACE, 1981. Van Gelder, K., M.J.J. Simon-Thomas, and C.J. Kroese. “Hydrogen-Induced Cracking: Determination of Maximum Allowed H2S Partial Pressures.” CORROSION/85, paper no. 85235. Houston, TX: NACE, 1985. Wilde, B.E., C.D. Kim, and E.H. Phelps. “Some Observations on the Role of Inclusions in the Hydrogen-Induced Blister Cracking of Line Pipe Steels in Sulfide Environments.” CORROSION/80, paper no. 80007. Houston, TX: NACE, 1980.

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NACE International Section 5: Inhibitors 5.1 Summary 5.1.1 Overview: The papers reviewed included attempts at modeling general corrosion, HIC, and hydrogen permeation in dehydrated sour gas and sour crude oil pipelines. In general, it was found that inhibitors reduce corrosion and hydrogen permeation, but the types of inhibitors and the conclusions on their effectiveness varied. Tested inhibitors included monoethanolamine (MEA) and morpholine, more commonly thought of as neutralizers rather than surface-active inhibitors. Surface preparation was considered in one study that found rust dramatically increased both general corrosion and HIC, whereas mill scale had just the opposite effect. Several papers reported the use of laboratory techniques intended to model field operations, but no link between the laboratory results and service experience has been confirmed. Furthermore, the methods used in the laboratory have not generally been taken to the field. It has been shown that no overall correlation existed between HIC and general corrosion rates. However, other investigators have shown that there has been a relationship between hydrogen permeation and general corrosion rate and that they have been affected either individually or separately by the addition of inhibitors. 5.1.2 Materials: All of the inhibitor papers involved carbon steel. 5.1.3 Environment: Most of the studies were performed in a synthetic seawater or NACE Standard TM0177 test solution saturated with H2S. Triethyleneglycol (TEG) was used to simulate dehydrated sour gas at 1,650 kPa (240 psi). Test conditions included pH from 2.8 to 6.3, H2S concentrations from 0 to 1.2%, chloride concentrations from 0 to 1.8%, addition of up to 0.5% acetic acid, and cyanide additions. 5.1.4 Types of Test Methods: Three-point bend specimens were used for HIC studies, stressed and unstressed, for 15 to 20 days. Linear polarization resistance (LPR) measurements, hydrogen-permeation measurements, and cathodic polarization were used with varying degrees of success. 5.2 Overview Discussion 5.2.1 Important Trends: HIC and general corrosion did not appear to be directly related. Monoethanolamine (MEA) reduced HIC susceptibility relative to aqueous environments, but very high (up to 3%) concentrations were required. Rusted surfaces tended to pit and experienced cracking damage more readily than unrusted steel. 5.2.2 Relevance to Wet H2S Refinery Operations: The high MEA treatment levels to mitigate HIC were considered impractical for service applications. Sulfiding of surfaces caused questionable LPR measurement results in H2S-rich environments, which led to some confusion in test results. Hydrogen-permeation measurements and cathodic polarization were considered the best available (in 1988) methods for inhibitor evaluation. 5.2.3 Implications for Service Based on Data: Studies have shown that rusted surfaces on equipment in service do not offer protection from hydrogen permeation in wet H2S service environments. The literature also indicates that steps have been taken to eliminate rusted surfaces and that some filming inhibitors have been used successfully to reduce hydrogen absorption in these environments. 5.3 Limitations in Available Data or Information: There was no good field test used to verify the conclusions of the various authors. No mechanistic conclusions were drawn in the papers, except for the conclusion that rust quickly reduced to iron sulfide and elemental sulfur and caused increased corrosion. For some inhibitors, low inhibitor dosages actually increased problems associated with hydrogen permeation. All of the work published addressed â&#x20AC;&#x153;wettedâ&#x20AC;? areas of equipment, but much of the equipment in wet H2S cracking service was exposed almost exclusively to vapors, except for surface condensation and possibly entrained liquids, so transport questions on inhibitor effectiveness still have not been resolved completely. 5.4 Observations Based on Existing Data: Surface-active inhibitors have been effective in inhibiting general corrosion and, in some cases, hydrogen permeation. MEA at relatively high concentrations inhibited HIC. 5.5 Areas of Insufficient Understanding Regarding Inhibitors: Because of the limited amount of documented plant data on the effects of inhibitors on HIC, an accepted laboratory method for testing inhibitors that accurately models actual field performance has not been identified.

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NACE International Bibliography Christensen, C.J., E.E. Maahn, and C. Juhl. “Evaluation of Inhibitors for Sour Crude Oil Transmission Pipelines.” CORROSION/88, paper no. 88198. Houston, TX: NACE, 1988. Latos, E.J. “Evaluation of Inhibitors for Control of Corrosion in Crude Distillation Units.” CORROSION/79, paper no. 26. Houston, TX: NACE, 1979. Nobe, K., and Y. Saito. “Sulfide-Promoters and Acetylenic Inhibitors of Hydrogen Penetration of 4130 Steel.” Werkstoffe und Korrosion (Materials and Corrosion) 34, 7 (1983): p. 348. Schmitt, G., W. Bruckhoff, and G. Lohe. “Influence of Corrosion Products on the Efficiency of Inhibitors in Sour Gas Service.” CORROSION/87, paper no. 87033. Houston, TX: NACE, 1987. Sriskandarajah, T., H.C. Chan, and A. Tseung. “A Method for the Inhibition of Sulphide Stress Corrosion Cracking in Steel—I. Electrochemical Aspects.” Corrosion Science 25, 6 (1985): p. 383. Sriskandarajah, T., H.C. Chan, and A. Tseung. “A Method for the Inhibition of Sulfide Stress Corrosion Cracking in Steel—II. Mechanical Aspects.” Corrosion Science 25, 6 (1985): p. 395. Suzuki, K., T. Kouno, T. Murata, and E. Sato. “Study of Inhibitors for Sour Gas Service.” Corrosion 38, 7 (1982): p. 384.

Section 6: Role of H2S in SCC in Amine Solutions 6.1 Summary 6.1.1 Overview: Of the technical papers that were reviewed addressing SCC in amine solutions, two were industry surveys and offered no discussion of cracking mechanisms, one described a failure of an amine contactor that was found to be caused by SOHIC (not SCC) of a non-stress-relieved weld, and the other five addressed SCC in amine solutions and provided the data discussed below. 6.1.2 Materials Grades and Product Form: Most laboratory work was performed on ASTM A516 grade 70 carbon steel. One of the surveys listed all the various specifications and grades of steel reported to be in use in amine units: ASTM A516 grade 70, A285, and A106.16 6.1.3 Environments: • H2S: 0 to 0.1 MPa (0 to 1 atm) in gas and up to 0.06 mol/mol MEA or DEA • Cl : up to 0.06% by weight

• pH: 8 to 12 • Temperature: 25 to 116 °C (77 to 240 °F) • CN-: up to 700 ppm 6.1.4 Test Methods: Potentiodynamic polarization, slow strain rate tests. 6.2 Overview Discussion 6.2.1 Important Trends in the Data: The majority of papers established that SCC of carbon steel in amine solutions was intergranular in nature. However, SCC has not been observed in pure alkanolamine systems. Contaminants in solution were required for intergranular cracking of carbon steel to be initiated and propagated. The combination of CO2 and carbonate was the basic crack-inducing agent, whereas H2S in more than trace amounts acted as an inhibitor. Other vital crack-inducing contaminants in combination with carbonates were sulfur-bearing compounds such as thiosulfate or thiocyanate, chloride, and cyanide. SCC in amine solutions was most prevalent in MEA solutions. Cracking was enhanced at elevated temperatures such as 116 °C (240 °F), but has been observed at temperatures as low as 38 °C (100 °F). Amine strength was an important parameter influencing both cracking intensity and failure mode. The SCC mechanism in amine solutions was anodic (governed

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NACE International by iron dissolution) and was not directly related to cracking mechanisms associated with the formation of hydrogen, such as HIC, SOHIC, and SSC. 6.2.2 Relevance to Wet H2S Refinery Operations: SCC in amine solutions was related to carbonate-type intergranular cracking in refinery sour water. Although there has usually been no alkanolamine present in sour refinery waters, the alkaline environment was common to both mechanisms. 6.2.3 Implications for Service Based on Data: Several literature sources indicated that stress relieving of carbon steel welds was necessary for all service temperatures to minimize SCC in MEA units. Stress relieving of carbon steel welds above service temperatures of 66 to 88 °C (150 to 190 °F) has been considered for other alkanoamine solutions. Guidelines for minimizing SCC in amine units have been provided in API RP 945.17 6.2.3.1 Contaminants in the solvent have been shown to be an important consideration. However, critical limits for carbonate, thiosulfate, thiocyanate, chloride, and cyanide have not been established. 6.2.3.2 The published literature indicated that the amine strength was a critical parameter. Intergranular SCC of carbon steel welds was most prevalent in contact with contaminated lean (≤ 25%) MEA solutions. Higher amine strengths were generally less severe from the standpoint of cracking. 6.3 Limitations in Available Data or Information 6.3.1 Data gathered in an industry survey is sometimes not necessarily related to just intergranular SCC in amine solutions. This uncertainty makes interpretation of the data difficult. Data that were supported by metallographic analyses have been collected. 6.3.2 Stress relief of carbon steel welds has been used extensively with apparent success to mitigate SCC in alkanolamine solutions. Whether stress relieving actually prevents or only delays and retards the cracking activity has not been conclusively established. 6.4 Observations Based on Existing Data 6.4.1 The literature described a SCC mechanism of carbon steel in amine solutions that has been proposed as follows: 6.4.1.1 Carbonate/bicarbonates in alkanolamine solutions have been observed to form a protective magnetite film on steel surfaces, whose potential canshift into the cracking range if certain impurities are present in the system. When the magnetite film is in contact with MEA or DEA solutions containing weak sulfiding agents, it incorporates sulfides into its structure and thereby suffers a weakening of its protective property. Contamination by chloride and/or cyanide is then assumed to locally rupture the destabilized steel surface film so that SCC can proceed. 6.5 Areas of Insufficient Understanding Regarding SCC in Amine Solutions 6.5.1 Cracking of as-welded carbon steel equipment has occurred in refinery amine service via an intergranular SCC mechanism. The limiting conditions for such cracking in the various alkanolamine solutions used in refinery service have not yet been well defined.

Bibliography Lenhart, S.J., H.L. Craig, and J.D. Howell. “Diethanolamine Stress Corrosion Cracking of Mild Steel.” CORROSION/86, paper no. 86212. Houston, TX: NACE, 1986. Lyle, F.F., Jr. “Stress Corrosion Cracking of Steels in Amine Solutions Used in Natural Gas Treatment Plants.” CORROSION/88, paper no. 88158. Houston, TX: NACE, 1988. McHenry, H.I., D.T. Read, and T.R. Shives. “Failure Analysis of an Amine-Absorber Pressure Vessel.” MP 26, 8 (1987): p. 18. Parkins, R.N., and Z.A. Foroulis. “Stress Corrosion Cracking of Mild Steel in Monoethanolamine Solutions.” MP 27, 1 (1988): p. 19. Parkins, R.N., A. Alexandridou, and P. Majumdar. “Stress Corrosion Cracking of C-Mn Steels in Environments Containing Carbon Dioxide.” MP 25, 10 (1986): p. 20.

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NACE International Richert, J.P., A.J. Bagdasarian, and C.A. Shargay. “Stress Corrosion Cracking of Carbon Steel in Amine Systems.” CORROSION/87, paper no. 87187. Houston, TX: NACE, 1987. Schillmoller, C.M. “Amine Stress Cracking: Causes and Cures. Hydrogen Processing.” Hydrocarbon Process. 65, 6 (1986): p. 37. Schutt, H.U. “New Aspects of Stress Corrosion Cracking in Monoethanolamine Solutions.” MP 27, 12 (1988): p. 53.

References 1. ASTM A333/A333M (latest revision), “Standard Specification for Seamless and Welded Steel Pipe for Low-Temperature Service” (West Conshohocken, PA: ASTM). 2. ASTM A516/A516M (latest revision), “Standard Specification for Pressure Vessel Plates, Carbon Steel, for Moderate and Lower Temperature Service” (West Conshohocken, PA: ASTM). 3. ASTM A537/A537M (latest revision), “Standard Specification for Pressure Vessel Plates, Heat Treated, Carbon Manganese Silicon Steel” (West Conshohocken, PA: ASTM). 4. ASTM A633/A633M (latest revision), “Standard Specification for Normalized High Strength Low Alloy Structural Steel Plates” (West Conshohocken, PA: ASTM). 5. ASTM A508/A508M (latest revision), “Standard Specification for Quenched and Tempered Vacuum Treated Carbon and Alloy Steel Forgings for Pressure Vessels” (West Conshohocken, PA: ASTM). 6. ASTM A350/A350M (latest revision), “Standard Specification for Carbon and Low Alloy Steel Forgings, Requiring Notch Toughness Testing for Piping Components” (West Conshohocken, PA: ASTM). 7. NACE Standard TM0177 (latest revision), “Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking and Stress Corrosion Cracking in H2S Environments” (Houston, TX: NACE). 8. NACE Standard TM0284 (latest revision), “Evaluation of Pipeline and Pressure Vessel Steels for Resistance to HydrogenInduced Cracking” (Houston, TX: NACE). 9. ASTM D1141 (latest revision), “Standard Practice for the Preparation of Substitute Ocean Water” (West Conshohocken, PA: ASTM). 10. NACE SP0472 (latest revision), “Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments” (Houston, TX: NACE). 11. NACE MR0175/ISO 15156 (latest revision), “Petroleum and natural gas industries—Materials for use in H2S-containing environments in oil and gas production” (Houston, TX: NACE). 12. ASTM A285/A285M (latest revision), “Standard Specification for Pressure Vessel Plates, Carbon Steel, Low and Intermediate Tensile Strength” (West Conshohocken, PA: ASTM). 13. API Spec 5L (latest revision), “Specification for Line Pipe” (Washington, DC: API). 14. ASME Boiler and Pressure Vessel Code (latest revision) (New York, NY: ASME). 15. ANSI/ASME Code for Pressure Piping, B31 (latest revision) (New York, NY: ANSI). 16. ASTM A106 (latest revision), “Standard Specification for Seamless Carbon Steel Pipe for High Temperature Service” (West Conshohocken, PA: ASTM). 17. API RP 945 (latest revision), “Avoiding Environmental Cracking in Amine Units” (Washington, DC: API).

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NACE International Appendix A: Cross-Reference Listing of ASTM, AISI, and UNS Designations This appendix is intended to provide supplementary information only, although it may contain mandatory or recommending language in specifications or procedures that are included as examples of those that have been used successfully. Nothing in this appendix shall be construed as a requirement or recommendation with regard to any future application of this technology.

Table A1 Cross-Reference Listing of ASTM, AISI, and UNS Designations for Materials Listed in This Report ASTM

AISI

UNS

A106A

K02501

A106B

K03006

A106C

K03501

A285A

K01700

A285B

K02200

A285C

K02801

A350 (LF1)

K03009

A350 (LF2)

K03011

A350 (LF3)

K32025

A350 (LF5)

K13050

A350 (LF9)

K22036

A508 (1)

K13502

A508 (2, 2a)

K12766

A508 (3, 3a)

K12042

A508 (4, 4a, 4b)

K22375

A508 (5, 5a)

K42365

A516 (55)

K01800

A516 (60)

K02100

A516 (65)

K02403

A516 (70)

K02700

A537M

K02400

A537M

K12437

A633

K01803

A633A

K01802

A633C

K12000

A633D

K12037

A633E

K12202

304

S30400

316

S31600

316L

S31603

410

S41000

1020

G10200

4130

G41300

4340

G43400

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NACE Standard MR0103-2012 Item 21305

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Standard Material Requirements Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments

This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone, whether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents minimum requirements and should in no way be interpreted as a restriction on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE International assumes no responsibility for the interpretation or use of this standard by other parties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies, which preclude the issuance of interpretations by individual volunteers.

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CAUTIONARY NOTICE: NACE International standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication. The user is cautioned to obtain the latest edition. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 281-228-6200).

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Users of this NACE International standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International standard may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard.

Revised 2012-06-23 Revised 2010-10-22 Revised 2007-07-19 Revised 2005-05-23 Approved 2003-03-15 NACE International 1440 South Creek Dr. Houston, Texas 77084-4906 +1 281-228-6200 ISBN 1-57590-168-4 ÂŠ 2012, NACE International

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MR0103-2012

Foreword

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_________________________________________________________________________

This NACE standard establishes material requirements for resistance to sulfide stress cracking (SSC) in sour refinery process environments, i.e., environments that contain wet hydrogen sulfide (H2S). It is intended to be used by refineries, equipment manufacturers, engineering contractors, and construction contractors.

The term “wet H2S cracking” as used in the refining industry covers a range of damage mechanisms that can occur because of the effects of hydrogen charging in wet H2S refinery or gas plant process environments. One of the types of material damage that can occur as a result of hydrogen charging is SSC of hard weldments and microstructures, which is addressed by this standard. Other types of material damage include hydrogen blistering, hydrogen-induced cracking (HIC), and stress-oriented hydrogen-induced cracking (SOHIC), which are not addressed by this standard. (1)

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The materials, heat treatments, and materials property requirements set forth in this standard represent the best judgment and experience of TG 231 and its two sponsors, Specific Technology Group (STG) 34, “Petroleum Refining and Gas Processing Industry Corrosion,” and STG 60, “Corrosion Mechanisms.” In many cases this judgment is based on extensive experience in the oil and gas production industry, as documented in NACE MR0175/ISO 15156, and has been deemed relevant to the refining industry by the task group.

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Historically many end users, industry organizations (e.g., API ), and manufacturers that have specified and supplied equipment and products such as rotating equipment and valves to the (2) 1 refining industry have used NACE MR0175/ISO 15156 to establish materials requirements to prevent SSC. However, it has always been recognized that refining environments are outside the scope of NACE MR0175/ISO 15156, which was developed specifically for the oil and gas production industry. In 2000, NACE Task Group (TG) 231 was formed to develop a refineryspecific sour service materials standard. This standard is based on the good experience gained with NACE MR0175/ISO 15156, but tailored to refinery environments and applications. Other 2 3 references for this standard are NACE SP0296, NACE Publication 8X194, NACE Publication 4 8X294, and the refining experience of the task group members.

(1) (2)

American Petroleum Institute (API), 1220 L St. NW, Washington, DC 20005-4070. International Organization for Standardization (ISO), 1 ch. de la Voie-Creuse, Case postale 56, CH-1211 Geneva 20, Switzerland.

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MR0103-2012

Whenever possible, the recommended materials are identified by accepted generic descriptors (3) (4) (5) (6) (such as UNS numbers) and/or accepted standards, such as AISI, API, ASTM, ASME, (7) (8) ANSI, or BSI standards. This NACE standard updates and supersedes all previous editions of NACE Standard MR0103. It was originally prepared in 2003 and was revised in 2005, 2007, 2010, and 2012 by NACE TG 231, “Petroleum Refining Sulfide Stress Cracking (SSC): Review of NACE Standard MR0103.” TG 231 is administered by STG 34, “Petroleum Refining and Gas Processing.” It is also sponsored by STG 60, “Corrosion Mechanisms.” This standard is issued by NACE International under the auspices of STG 34.

In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must are used to state a requirement, and are considered mandatory. The term should is used to state something good and is recommended, but is not considered mandatory. The term may is used to state something considered optional.

IS N

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_________________________________________________________________________

____________________________________________

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(3)

Unified Numbering System for Metals and Alloys (UNS). UNS numbers are listed in Metals & Alloys in the Unified Numbering System, latest revision (Warrendale, PA: SAE International and West Conshohocken, PA: ASTM International). (4) American Iron and Steel Institute (AISI), 1140 Connecticut Ave. NW, Washington, DC 20036. (5) ASTM International (ASTM), 100 Barr Harbor Dr., West Conshohocken, PA 19428-2959. (6) ASME International (ASME), Three Park Avenue, New York, NY 10016-5990. (7) American National Standards Institute (ANSI), 25 West 43 rd St., 4th Floor, New York, NY 10036. (8) BSI British Standards (BSI) (formerly British Standards Institution), 389 Chiswick High Road., London W4 4AL, U.K.

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MR0103-2012

_________________________________________________________________________

NACE International Standard Material Requirements

Contents

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Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments

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1. General .......................................................................................................................... 1 2. Ferrous Materials ............................................................................................................ 7 3. Nonferrous Materials ..................................................................................................... 13 4. General Fabrication Requirements ............................................................................... 16 5. Bolting ........................................................................................................................... 18 6. Plating, Coatings, and Diffusion Processes .................................................................. 19 7. Special Components ..................................................................................................... 19 8. Valves ........................................................................................................................... 21 9. Compressors and Pumps ............................................................................................. 21 References ........................................................................................................................ 21 Appendix A: Sulfide Species Plot (Nonmandatory) ......................................................... 24 Appendix B: Background Information on Hardness Testing and Requirements (Nonmandatory) .......................................................................................................... 25 Appendix C: Welding Procedure Qualification Hardness Survey Layouts (Mandatory) ... 28 Appendix D: Duplex Stainless Steel Welding Considerations .......................................... 32 FIGURES: Figure A1: Sulfide Species Plot for Closed System at 25 °C (77 °C) ............................... 24 Figure C1: Hardness test locations ................................................................................... 29 Figure C2: Hardness test details ....................................................................................... 31 TABLES Table 1: “Road Map” for this Standard ................................................................................ 6 Table 2: Maximum Hardness Requirements for P-Numbered Alloy Steels ........................ 8 Table 3: Chemical Composition Requirements for Austenitic Stainless Steels ............... 11 Table 4: Maximum Hardness Requirements for Weldments in Precipitation-Hardenable Stainless Steels ........................................................................................................... 13 Table 5: Cold-Worked Nickel-Chromium-Molybdenum Alloys and Maximum Hardness Requirements .............................................................................................................. 14 Table 6: Precipitation-Hardenable Nickel Alloys, Conditions, and Maximum Hardness Requirements ............................................................................................................. 15 Table 7: UNS R30035 Heat Treatments ........................................................................... 15 Table 8: Titanium Alloys, Conditions, and Maximum Hardness Requirements ................ 16 Table 9: Common Bolting Materials That Meet Section 2 and Section 3 Requirements .. 19 Table B1: Portable Hardness Testing Standards ............................................................. 26 Table D1: Duplex Stainless Steel Base Metal Groupings ................................................. 34 _________________________________________________________________________

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MR0103-2012 _________________________________________________________________________ Section 1: General 1.1 Scope

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1.1.1 This standard establishes material requirements for resistance to SSC in sour petroleum refining and related processing environments containing H2S either as a gas or dissolved in an aqueous (liquid water) phase with or without the presence of hydrocarbon. This standard does not include and is not intended to include design specifications. Other forms of wet H2S cracking, environmental cracking, corrosion, and other modes of failure, although outside the scope of this standard, should be considered in the design and operation of equipment. Severely corrosive and/or hydrogen charging conditions may lead to failures by mechanisms other than SSC and should be mitigated by methods that are outside the scope of this standard. 1.1.2 Specifically, this standard is directed at the prevention of SSC of equipment (including pressure vessels, heat exchangers, piping, valve bodies, and pump and compressor cases) and components used in the refining industry. Prevention of SSC in carbon steel materials categorized under P-No. 1 in Section IX of the ASME Boiler and Pressure 5 6 Vessel Code (BPVC) is addressed by requiring compliance with NACE SP0472.

Note: There are a number of instances in which this standard specifically references the ASME BPVC. This reference is based on historical development of the standard, but is not intended to preclude the use of other pertinent codes and standards where they are appropriate.

1.2 Applicability

1.2.1 This standard applies to all components of equipment exposed to sour refinery environments (see Paragraph 1.3) where failure by SSC would (1) compromise the integrity of the pressure-containment system, (2) prevent the basic function of the equipment, and/or (3) prevent the equipment from being restored to an operating condition while continuing to contain pressure.

1.2.2 It is the responsibility of the user to determine the operating conditions and to specify when this standard applies.

1.2.3 It is the userâ&#x20AC;&#x2122;s responsibility to ensure that a material will be satisfactory in the intended environment. The user may select specific materials for use on the basis of operating conditions that include pressure, temperature, corrosiveness, and fluid properties. A variety of candidate materials may be selected from this standard for any given component. Unlisted materials may also be used based on either of the following processes:

(a) If a metallurgical review based on scientific and empirical knowledge indicates that the SSC resistance will be adequate. These materials may then be proposed for inclusion into the standard using methods in Paragraph 1.6. (b) If a risk-based analysis indicates that the occurrence of SSC is acceptable in the subject application.

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1.3 Factors Contributing to SSC

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1.2.4 The manufacturer is responsible for meeting metallurgical requirements.

1.3.1 SSC is defined as cracking of a metal under the combined action of tensile stress and corrosion in the presence of water and H2S. SSC is a form of hydrogen stress cracking resulting from absorption of atomic hydrogen that is produced by the sulfide corrosion reaction on the metal surface. 1.3.2 SSC in refining equipment is affected by complex interactions of parameters including: (a) chemical composition, strength (as indicated by hardness), heat treatment, and microstructure of the material exposed to the sour environment; (b) total tensile stress present in the material (applied plus residual); (c) the hydrogen flux generated in the material, which is a function of the environment (i.e., presence of an aqueous phase, H2S concentration, pH, and other environmental parameters such as bisulfide ion concentration and presence of free cyanides);

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MR0103-2012 (d) temperature; and (e) time. 1.3.3 Material susceptibility to SSC is primarily related to material strength (as indicated by hardness), which is affected by chemical composition, heat treatment, and microstructure. Materials with high hardness generally have an increased susceptibility to SSC. 1.3.3.1 SSC has not generally been a concern for carbon steels typically used for refinery pressure vessels and piping in wet H2S service because these steels have sufficiently low hardness levels.

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1.3.3.2 Improperly heat-treated materials, weld deposits, and heat-affected zones (HAZs) may contain regions of high hardness. 1.3.4 SSC susceptibility for a given material increases with increased tensile stress.

1.3.4.1 Residual stresses contribute to the overall tensile stress level. High residual stresses associated with welds increase susceptibility to SSC.

1.3.4.2 Control of weldment hardness, with or without reduction of residual stresses, is a recognized method for preventing SSC, as outlined in NACE SP0472 for P-No. 1 carbon steels.

1.3.5 Susceptibility to SSC is also related to the hydrogen permeation flux in the steel, which is primarily associated with two environmental parameters: pH and total sulfide content of the aqueous phase. In a closed system at equilibrium condition, – 2– dissolved hydrogen sulfide (H2Saq), bisulfide ion (HS ), and sulfide ion (S ) (sometimes called “soluble sulfide”) exist in an aqueous solution in different pH ranges. The sulfide species plot exhibited in Figure A1 in Appendix A (nonmandatory) shows their relative amounts present in an aqueous solution at 25 °C (77 °F) as a function of pH. At pH less than 6, H2Saq is the dominant (> 90% of total) sulfide specie present in the aqueous phase. At pH between 8 and 11, the dominant (> 90% of – total) sulfide specie present in the aqueous phase is HS . At pH greater than 13, the dominant (> 90% of total) sulfide specie 2– – 2– present in the aqueous phase is S . At pH 7, the system contains 50% H2Saq, 50% HS , and virtually no S . At pH 12, the – 2– system contains 50% HS , 50% S , and virtually no H2Saq. The total sulfide content therefore refers to the total amount of all – 2– three sulfide species present in the aqueous phase (i.e., the sum of H2Saq, HS , and S ). Typically, the hydrogen flux in steels has been found to be lowest in near-neutral pH solutions, with increasing flux at both lower and higher pH values. Corrosion at lower pH values is typically caused by H2Saq, whereas corrosion at higher pH values is typically caused by high – concentrations of HS . In many refinery sour water environments, the presence of dissolved ammonia (NH3) increases the – pH, thereby increasing the solubility of H2S and resulting in a high HS concentration. At elevated pH, the presence of free – cyanides, which include dissolved hydrogen cyanide (HCNaq) and cyanide ion (CN ), can further aggravate the degree of atomic hydrogen charging into the steel. Even though SSC susceptibility is known to increase with total sulfide content of the aqueous phase, the presence of as little as 1 ppmw total sulfide in the aqueous phase can cause SSC under conditions that promote aggressive hydrogen charging.

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(a) > 50 ppmw total sulfide content in the aqueous phase; or

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1.3.5.1 Some environmental conditions known to cause SSC are those containing an aqueous phase and:

(b)  1 ppmw total sulfide content in the aqueous phase and pH < 4; or (c)  1 ppmw total sulfide content and  20 ppmw free cyanide in the aqueous phase, and pH > 7.6; or (d) > 0.3 kPa absolute (0.05 psia) partial pressure H2S in the gas phase associated with the aqueous phase of a process.

1.3.5.2 The high-pH sour environments differentiate refinery sour service from the oil and gas production sour environments covered by NACE MR0175/ISO 15156, because many wet sour streams in production also contain carbon dioxide and hence exhibit a lower pH. Another major difference is that chloride ion concentrations tend to be significantly lower in refinery sour services than in oil production sour services. 1.3.6 The hydrogen charging potential increases with increasing temperature provided the aqueous phase is not eliminated by the elevated temperature. Elevated temperature promotes dissociation of H2S (thereby producing more monatomic hydrogen), and increases the diffusion rates of monatomic hydrogen in metals, thereby promoting hydrogen charging.

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MR0103-2012 However, cracking potential is maximized at near-ambient temperature. This distinction is important because metals can become charged during high-temperature exposure and subsequently crack during excursions to lower temperatures (such as during shutdowns). 1.3.7 The time to failure decreases as material strength, total tensile stress, and environmental charging potential increase. Exposure time to cause SSC can be very short if the other SSC factors favor susceptibility. Some susceptible equipment can fail even during short sour water excursions such as those encountered during equipment shutdowns.

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1.3.8 The end user shall determine whether the parameters necessary to cause SSC exist in the process environment, and whether the equipment falls within the scope of this standard. The end user may rely on experience, risk-based analysis, or the above guidance (notably that related to environmental conditions provided in Paragraphs 1.3.5 and 1.3.6) to make this determination. When determining whether the equipment falls within the scope of this standard, consideration should be given to all plant operating scenarios and the likely impact on the materials of construction, i.e., normal operations, operational upsets, alternate (possible future) operations, and start-up/shutdown conditions (e.g., presulfiding of catalysts). 1.4 Materials Included in This Standard

1.4.1 Materials included in this standard are resistant to, but not necessarily immune to, SSC. Materials have been included based on their demonstrated resistance to SSC in field applications, in SSC laboratory testing, or both.

1.4.2 Listed materials do not all exhibit the same level of resistance to SSC. Standard laboratory SSC tests, such as those 7 addressed in NACE Standard TM0177, are accelerated and severe tests. Materials that successfully pass these tests are generally more resistant to cracking in sour service than materials that fail the tests. Many alloys included in this standard perform satisfactorily in sour service even though they may crack in laboratory tests. 1.4.3 Improper design, processing, installation, or handling can cause resistant materials to become susceptible to SSC.

1.5 Hardness Requirements

1.4.4 No effort has been made in this standard to rank materials based on their relative resistance to SSC. Selection of the appropriate material for a given application depends on a number of factors, including mechanical properties, corrosion resistance, and relative resistance to SSC, and is beyond the scope of this standard.

1.5.1 Hardness is related to tensile strength, a primary factor in SSC susceptibility. Because hardness testing is nondestructive and requires relatively minor component/specimen preparation compared with tensile testing, it is commonly used by manufacturers in production quality control and by users in field inspection. As such, a maximum allowable hardness is specified as a primary requirement for many of the materials in this standard.

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1.5.3 Hardness testing and reporting shall be performed in strict compliance with the methods described in the appropriate ASTM or ISO standards, which are listed in the References section. Appendix B also lists the appropriate standards for the various test methods.

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1.5.2 Several different hardness scales are used in this standard. The most commonly used scales are Rockwell “C” (HRC), Rockwell “B” (HRBS), Brinell (HBW), and Vickers 49 N (5 kgf) or 98 N (10 kgf) (HV 5 or HV 10). Background information on these hardness scales and the logic behind the various references is provided in Appendix B (nonmandatory).

1.5.4 The standard test parameters (indenters, loads, and major-load dwell time) shall be used for all Rockwell hardness tests. The specimen temperature for Rockwell hardness testing shall be 10 to 35 °C (50 to 95 °F). No lubricant shall be used. Because Brinell hardness tests are only indicated for steel materials in this standard, all Brinell hardness tests shall be performed using 29.4 kN (3,000 kgf) load, a 10 mm indenter, and the standard dwell time of 10 to 15 s. 1.5.5 In some cases, maximum allowable hardness values are provided in both HRC (or HRBS) and HBW. In those instances, either scale may be used. 1.5.6 When hardness requirements are stated in HBW, and testing using stationary Brinell hardness equipment is not viable, testing shall be performed using the comparison hardness test method (commonly, but incorrectly, referred to as portable Brinell hardness testing). 8

1.5.7 When applicable, the conversion tables in ASTM E140 or ISO 18265 shall be used for conversion of hardness values obtained by other test methods to HRC, HRBS, or HBW values. However, tables for many materials do not exist in

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MR0103-2012 those standards. The tables should be used only for materials that are specifically listed. Conversions may be performed based on empirical data for materials that are not covered when approved by the user. When converted hardness values are used, they shall be reported in accordance with the requirements specified in ASTM E140 or ISO 18265. 1.5.8 Sufficient hardness tests shall be made to establish the actual hardness of the material being examined. Individual hardness readings exceeding the permitted value may be considered acceptable if the average of several readings taken within close proximity does not exceed the permitted value and no individual reading exceeds the specified value by more than 2 HRC (or by more than 5% in the case of HBW or HV 10). 10

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1.5.9 Acceptance criteria for microhardness testing using Knoop or Vickers hardness test methods (see ASTM E384 ) are outside the scope of this standard. See Appendix B for more information. 1.5.10 The use of portable hardness testing methods to verify compliance with the requirements of this standard is prohibited unless explicitly approved by the end user. The one exception that does not require end user approval is the use of 11 comparison hardness testing in accordance with ASTM A833 to evaluate weld deposits as specified in NACE SP0472. See Appendix B (nonmandatory). 1.6 Procedure for the Addition of New Materials or Processes

1.6.1 NACEâ&#x20AC;&#x2122;s standard letter balloting process shall be used for the addition of new materials and/or processes to this standard.

1.6.3 Field Experience Data Requirements

1.6.2 Materials may be balloted based on field experience and/or laboratory test data.

1.6.3.1 Field experience data shall fully document the alloy composition(s), condition(s), and hardness level(s), the process fluid parameters that influence SSC, and the exposure history.

1.6.3.2 In certain alloy families (such as duplex stainless steels), microstructure is also a critical variable, and shall also be documented. 1.6.4 Laboratory Test Data Requirements

1.6.4.1 The laboratory testing of materials shall be performed to a level of severity in accordance with NACE Standard TM0177. If actual service conditions are outside these limits, SSC of approved materials may be possible.

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1.6.4.3 A minimum of three test specimens from each of three different commercially prepared heats must be tested in the condition balloted for inclusion. The composition of each heat and the heat treatment(s) used shall be furnished as part of the ballot. The candidate materialâ&#x20AC;&#x2122;s composition range and/or UNS number and its heat-treated condition requested for inclusion in this standard must be included with the ballot.

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1.6.4.2 The candidate material must be tested in accordance with the test procedures established in NACE Standard TM0177. The tensile bar, C-ring, bent beam, and double-cantilever beam test specimens described in NACE Standard TM0177 are accepted test specimens. Any of these test specimens may be used.

1.6.4.4 The hardness of each test specimen must be determined and reported as part of the ballot. The average hardness of each test specimen shall be the hardness of that test specimen. The minimum test specimen hardness obtained for a given heat/condition shall be the hardness of that heat/condition for the purpose of balloting. The maximum hardness requested for inclusion of the candidate material in this standard must be specified in the ballot and shall be supported by the data provided. 1.6.4.5 In certain alloy families (such as duplex stainless steels), microstructure is also a critical variable, and shall also be documented for each heat/condition. 1.6.4.6 For each of the tests performed, the testing details shall be reported as part of the ballot item being submitted.

1.7 New Restrictions and Deleted Materials

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MR0103-2012 1.7.1 The revision/ballot process may be used to impose new restrictions on materials or to delete materials from this standard. New restrictions may include such items as imposition of a maximum hardness requirement, reduction of a maximum hardness requirement, elimination of a previously acceptable heat-treatment condition, and elimination of a previously acceptable manufacturing process. 1.7.2 Affected materials in use at the time of the change that complied with a prior edition of this standard and that have not experienced H2S-enhanced environmental cracking in their current application are considered in compliance with this standard.

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1.7.3 When affected materials (see Paragraph 1.7.2) are eventually removed from their current application, replacement materials must be selected from acceptable materials in the current edition of this standard to be in compliance with this standard, except as noted in Paragraph 1.7.4. 1.7.4 New equipment manufactured from affected materials, as well as equipment refurbished using new components manufactured from affected materials, may be qualified for use in specific applications in accordance with Paragraph 1.8. 1.8 Qualification of Unlisted Alloys, Conditions, and/or Processes for Specific Applications

1.8.1 Alloys, conditions, and processes that are not listed in this standard may be qualified for use in specific sour applications. This section provides the minimum requirements for compliance with this standard when unlisted alloys, conditions, and/or processes for specific applications are qualified.

1.8.2 The user shall be responsible for determining the suitability of an unlisted alloy, condition, and/or process for a specific application based on laboratory test data, field experience, and/or risk-based analysis. 1.8.3 If laboratory testing is used as an acceptance basis, testing should be performed in accordance with accepted standard test methods such as those documented in NACE Standard TM0177. 1.8.4 If field experience and/or risk-based analysis is used as an acceptance basis, a number of factors should be considered:

(a) The stress level, material form, forming process, heat-treatment condition, microstructure, and mechanical properties (particularly hardness) of the field experience specimen should be well documented.

(b) The environmental conditions to which the field experience specimen is exposed should be well documented. (c) The field experience exposure time should be adequate to ensure that the unlisted alloy, condition, and/or process provides resistance to SSC.

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1.8.6 The composition, material form, forming processes, heat-treatment condition, and mechanical properties of equipment manufactured using an unlisted alloy, condition, and/or process should be controlled based on the corresponding information for the laboratory test specimens and/or field experience specimens.

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1.8.5 The suitability of the unlisted alloy, condition, and/or process for a specific application should be determined based on an evaluation of the environmental conditions in the intended specific application compared with the environmental conditions in the laboratory tests and/or the field experience.

1.8.7 Unlisted alloys, conditions, and/or processes qualified for specific applications based on the requirements in this section shall not become part of this standard unless they are approved through the NACE balloting process.

1.9 Standard Road Map For ease of use, Table 1 provides general information by material/application group, as well as references to specific paragraphs that cover applicable material and fabrication requirements.

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MR0103-2012 Table 1 â&#x20AC;&#x153;Road Mapâ&#x20AC;? for This Standard Material Groups

Conditions Allowed (a) Hot-rolled (b) Annealed (c) Normalized (d) Normalized and tempered (e) Normalized, austenitized, quenched, and tempered (f) Austenitized, quenched, and tempered. (a) Annealed (b) Normalized (c) Normalized and tempered (d) Normalized, austenitized, quenched, and tempered (e) Austenitized, quenched, and tempered.

Applicable Fabrication Requirement Paragraph(s) 2.1.8, Section 4

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Material Group or Application Carbon Steels

Applicable Material Requirement Paragraph(s) 2.1

2.1

2.1.8, Section 4

Alloy Steels

Annealed Annealed

2.2.2 2.3

2.2.3 Section 4

Specific Low-Carbon Martensitic Stainless Steels Austenitic Stainless Steels Specific Austenitic Stainless Steels Highly Alloyed Austenitic Stainless Steels Duplex Stainless Steels PrecipitationHardenable Stainless Steels Solid-Solution Nickel Alloys PrecipitationHardenable Nickel Alloys Cobalt-NickelChromiumMolybdenum Alloys Cobalt-NickelChromium-Tungsten Alloys Titanium Alloys Aluminum Alloys Copper Alloys

Quenched and double-tempered

2.4.2

2.4.3, Section 4

2.5

Section 4

Solution-annealed or hot-rolled

2.6

Section 4

Solution-annealed or solution-annealed and cold-worked

2.7

Section 4

Solution-annealed

2.8

2.8.2, Section 4

Solution-annealed and precipitationhardened

2.9

Section 4

Solution-annealed

3.1.1

Section 4

Various

3.1.2

Section 4

Various

3.2

Section 4

Not specified

3.3

Section 4

Various Not specified Not specified

3.4 3.5 3.6

Section 4 Section 4 Section 4

Ferritic Ductile Iron Ferritic Stainless Steels

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IS N

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Solution-annealed

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MR0103-2012 Material Groups

Conditions Allowed Various Various Various Various Various Various

Applicable Material Requirement Paragraph(s) Section 4 Section 5 Section 6 Section 7 Section 8 Section 9

Applicable Fabrication Requirement Paragraph(s) Section 4 N/A N/A Section 4 Section 4 Section 4

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Material Group or Application Fabrication Bolting Platings, Coatings Special Components Valves Compressors and Pumps

Conditions Allowed Applications

Applicable Fabrication Requirement Paragraph(s)

Material Group or Application

Applicable Material Requirement Paragraph(s)

_________________________________________________________________________

Section 2: Ferrous Materials 2.1 Carbon and Alloy Steel Materials

2.1.1 For the purposes of this standard, the terms “carbon steel” and “alloy steel” refer to alloys that meet the corresponding 12 definitions in ASTM A941. 2.1.2 Carbon and alloy steels shall:

(a) not contain intentional additions of elements such as lead, selenium, or sulfur to improve machinability; (b) meet the criteria of Paragraphs 2.1.7, 2.1.8, and Section 4; and

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hot-rolled (carbon steels only);

ii.

annealed;

iii.

normalized;

iv.

normalized and tempered;

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normalized, austenitized, quenched, and tempered; or

vi.

austenitized, quenched, and tempered.

2.1.3 Carbon steels listed as P-No. 1 Group 1 or 2 materials in Section IX of the ASME BPVC shall meet one of the conditions listed in Paragraph 2.1.2(c). Base-metal hardness controls are not required. 2.1.3.1 Welding of P-No. 1 carbon steels shall be controlled in accordance with Paragraph 2.1.8. 2.1.3.2 Bends in P-No. 1 piping formed by heating to above the upper critical temperature (Ac3) are allowed. The material shall have met one of the conditions listed in Paragraph 2.1.2 (c) prior to forming. The hardness in the bend area shall not exceed 225 HBW. 2.1.3.3 Weld repairs in P-No. 1 castings shall be performed in accordance with the welding requirements specified in Paragraph 2.1.8.3.

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MR0103-2012 2.1.4 Other carbon steels shall have a maximum hardness of 22 HRC (237 HBW). 2.1.5 Alloy steels included under the ASME BPVC Section IX P-numbers listed in Table 2 shall not exceed the indicated maximum hardness levels.

Table 2 Maximum Hardness Requirements for P-Numbered Alloy Steels

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Maximum Hardness 225 HBW 225 HBW 235 HBW 235 HBW 235 HBW 235 HBW 235 HBW 225 HBW 225 HBW 225 HBW 225 HBW 225 HBW 248 HBW

Alloy Steel P-No. 3 P-No. 4 P-No. 5A P-No. 5B P-No. 5C P-No. 6 P-No. 7 P-No. 10A P-No. 10B P-No. 10C P-No. 10F P-No. 11 P-No. 15E

2.1.6 Other alloy steels shall have a maximum hardness of 22 HRC (237 HBW).

2.1.7 Cold forming of carbon and alloy steels is allowed. The material shall have met one of the conditions listed in Paragraph 2.1.2(c) prior to cold forming. Cold-formed material shall be thermally stress relieved following any cold deforming by rolling, cold forging, or another manufacturing process that results in a permanent outer fiber deformation greater than 5%. Thermal stress relief shall be performed in accordance with the applicable ASME codes, except that the minimum stressrelief temperature shall be 593 Â°C (1,100 Â°F). After stress relieving, carbon steels listed as P-No. 1 materials in Section IX of the ASME BPVC shall meet a hardness requirement of 200 HBW maximum. Other carbon and alloy steels shall meet the appropriate hardness requirements in accordance with Paragraph 2.1.4, 2.1.5, or 2.1.6.

2.1.7.1 This requirement does not apply to cold work imparted by pressure testing in accordance with the applicable code. Cold-rotary straightened pipe is allowed only when permitted in API specifications. Cold-worked line pipe fittings 13 14 15 of ASTM A53 Grade B, ASTM A106 Grade B, API Spec 5L Grade X-42, or lower-strength grades with similar chemical compositions shall contain no more than 15% cold strain, and the hardness in the strained area shall not exceed 190 HBW.

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2.1.8.1 Fabrication welding and weld overlays shall be performed in accordance with the general requirements listed in Section 4.

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2.1.8 Welding and Overlays on Carbon Steels and Alloy Steels

2.1.8.2 Overlays applied to carbon and alloy steels for use in sour environments shall meet the requirements listed in Paragraphs 4.2 and 4.4 and in the following subparagraphs. 2.1.8.2.1 When applied to P-No. 1 carbon steels, partial weld overlays that do not qualify as cladding in accordance with Paragraph 4.4 shall be applied in such a way that the process-contacted interface between the overlay and the base metal has a HAZ and base metal hardness within the specified limits. Methods used to control the HAZ and base metal hardness, and acceptance criteria, shall be in accordance with NACE SP0472. 2.1.8.2.2 When applied to alloy steels or to non-P-No. 1 carbon steel materials, partial weld overlays that do not qualify as cladding in accordance with Paragraph 4.4 shall be post-weld heat treated in accordance with procedures that have been shown to return the process-contacted interface between the overlay and base metal to the specified HAZ and base metal condition (i.e., hardness). Hardness acceptance criteria shall be in accordance with limits provided in Paragraphs 2.1.3 through 2.1.6, and/or 2.1.8.4, as appropriate.

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MR0103-2012 2.1.8.2.3 When thermal-spray coatings are applied to P-No. 1 carbon steel materials in such a manner that any portion of the base metal exceeds the lower critical temperature (e.g., in the case of a spray and fuse coating), the procedures used shall ensure that the base metal has HAZ and base metal hardness within the specified limits. Methods used to control the HAZ and base metal hardness, and acceptance criteria, shall be in accordance with NACE SP0472.

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2.1.8.2.4 When thermal-spray coatings are applied to alloy steels or to non-P-No. 1 carbon steel materials in such a manner that any portion of the base metal exceeds the lower critical temperature (e.g., in the case of a spray and fuse coating), post-weld heat treatment (PWHT) shall be performed in accordance with procedures that have been shown to return the base metal to the specified HAZ and base metal condition (i.e., hardness). Hardness acceptance criteria shall be in accordance with limits provided in Paragraphs 2.1.3 through 2.1.6 and/or 2.1.8.4 as appropriate. 2.1.8.3 Weldments in carbon steels listed as P-No. 1 materials in Section IX of the ASME BPVC shall be produced using one or more of the methods outlined in NACE SP0472 to prevent excessive weldment hardness. 16

(9)

2.2 Cast Iron and Ductile Iron Materials

2.1.8.4 Some industry codes (such as ASME B31.3 and ANSI/NBBVI NB-23 ) allow welding of P-No. 3, P-No. 4, and P-No. 5A alloy steels without PWHT in certain circumstances. Non-PWHT procedures of this type may be used provided a hardness survey in accordance with Appendix C (mandatory) has been performed on a specimen taken from the welding procedure qualification test (WPQT) coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness limits. No individual hardness reading shall exceed 248 HV 10. Other alloy steel materials shall always receive PWHT when this standard applies to ensure low hardness in the weld deposit and HAZ. When PWHT is performed, a hardness survey in accordance with Appendix C shall be performed on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the PWHT time and temperature to produce weldments that meet the specified hardness limits.

2.2.1 Gray, austenitic, and white cast irons shall not be used as pressure-containing members. These materials may be used in internal components related to API and other appropriate standards, provided their use has been approved by the purchaser. 18

2.2.2 Ferritic ductile iron in accordance with ASTM A395 standards approve its use.

is allowed for equipment when API, ANSI, and/or other industry

2.2.3 Welding is not permitted on gray cast iron or ductile iron components. 2.3 Ferritic Stainless Steel Materials

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2.3.2 Weldments in ferritic stainless steels shall be produced using a weld procedure qualified by performing a hardness survey in accordance with Appendix C on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness (248 HV 10 maximum).

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2.3.1 Ferritic stainless steels shall be in the annealed condition and shall meet the criteria of Section 4. The hardness shall not exceed 22 HRC.

2.4 Martensitic Stainless Steel Materials 2.4.1 Martensitic stainless steels (UNS S41000, S42000, J91150 [CA15], and J91151 [CA15M]), either cast or wrought, shall be heat treated in accordance with Paragraph 2.4.1.1 and shall meet the criteria of Section 4. The hardness shall not exceed 22 HRC. Variations containing alloying elements such as lead, selenium, or sulfur to improve machinability shall not be used. Martensitic stainless steels that are in accordance with this standard have provided satisfactory field service in some sour environments. These materials may, however, exhibit threshold stress levels in NACE Standard TM0177 laboratory tests that are lower than the levels for other materials included in this standard. 2.4.1.1 Heat-Treatment Procedure (Three-Step Process) for UNS S41000, S42000, J91150 (CA15), and J91151 (CA15M) Martensitic Stainless Steel 2.4.1.1.1 Austenitize and quench or air cool.

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MR0103-2012 2.4.1.1.2 Temper at 621 °C (1,150 °F) minimum; then air cool to ambient temperature. 2.4.1.1.3 Temper at 621 °C (1,150 °F) minimum, but lower than the first tempering temperature; then air cool to ambient temperature. 2.4.2 Low-carbon, 12Cr-4Ni-Mo martensitic stainless steels, either cast UNS J91540 (CA6NM) or wrought UNS S42400, (10) shall be heat treated in accordance with Paragraph 2.4.2.1. The hardness shall not exceed 23 HRC. Variations containing alloying elements such as lead, selenium, or sulfur to improve machinability shall not be used. 2.4.2.1 Heat-Treatment Procedure (Three Step Process)

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2.4.2.1.1 Austenitize at 1,010 °C (1,850 °F) minimum and air or oil quench to ambient temperature. 2.4.2.1.2 Temper at 649 to 691 °C (1,200 to 1,275 °F) and air cool to ambient temperature. 2.4.2.1.3 Temper at 593 to 621 °C (1,100 to 1,150 °F) and air cool to ambient temperature. 2.4.3 Welding and Overlays on Martensitic Stainless Steels

2.4.3.1 Weldments in martensitic stainless steels listed in Paragraph 2.4.1 shall undergo a PWHT at 621 °C (1,150 °F) minimum. The welding procedure shall be qualified by performing a hardness survey in accordance with Appendix C on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness (248 HV 10 maximum). 2.4.3.2 Weldments in low-carbon martensitic stainless steels identified in Paragraph 2.4.2 shall undergo a double-cycle PWHT after first being cooled to ambient temperature. The double-cycle PWHT shall consist of heating at 671 to 691 °C (1,240 to 1,275 °F), cooling to ambient temperature, followed by heating at 579 to 621 °C (1,075 to 1,150 °F). The welding procedure shall be qualified by performing a hardness survey in accordance with Appendix C on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness (255 HV 10 maximum).

2.4.3.3 Welding shall only be performed on base materials listed in Paragraph 2.4.2 that have previously been austenitized, quenched, and double-tempered. Welding between martensitic stainless steels and other materials (including carbon steels, alloy steels, and austenitic stainless steels) is outside the scope of this standard.

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2.5 Austenitic Stainless Steel Materials

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2.4.3.4 Overlays applied to martensitic stainless steels by thermal processes such as welding, silver brazing, or thermal-spray systems are allowed for use in sour environments. In those cases in which the lower critical temperatures are exceeded, the component shall be heat treated or thermally stress relieved in accordance with procedures that have been shown to return the base metal to the specified maximum hardness level. The procedure shall be qualified by performing a hardness survey in accordance with Appendix C on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness (248 HV 10 maximum in the case of martensitic stainless steel materials identified in Paragraph 2.4.1, and 255 HV 10 maximum in the case of low-carbon martensitic stainless steel materials identified in Paragraph 2.4.2).

2.5.1 Austenitic stainless steels shall meet the chemical composition requirements specified in Paragraph 2.5.2, shall not exceed 22 HRC, shall be in the solution-annealed and quenched or solution-annealed and thermally stabilized condition, and shall be free of cold work intended to enhance their mechanical properties. Austenitic stainless steels containing lead or selenium for the purpose of improving machinability are not allowed. 2.5.2 Chemical composition requirements for the fully austenitic wrought product forms are shown in Table 3.

_______________________________ Brinell hardness measurements obtained on duplex stainless steels cannot be converted to Rockwell C hardness values using existing tables in ASTM E140. Use of empirically derived tables for this hardness conversion is subject to the approval of the user. (10)

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MR0103-2012 Table 3 (A) Chemical Composition Requirements for Austenitic Stainless Steels Mass Percent 0.10 max 16.0 min 8.0 min 2.0 max 2.0 max 0.045 max 0.04 max

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(A)

Element C Cr Ni Mn Si P S

The chemical compositions of the cast “austenitic” stainless steels often vary from those of their fully austenitic wrought counterparts to optimize casting characteristics. Many of these alloys are intentionally balanced to contain some ferrite, which renders them partially magnetic.

2.5.3 Unlisted elements, such as molybdenum, nitrogen, titanium, and niobium (columbium), are allowed, provided the chemical composition requirements in Paragraph 2.5.1 are met. 2.5.4 Higher carbon contents for UNS S30900 and UNS S31000 are allowed up to the limits of their respective specifications.

2.5.5 Welding and Overlays on Austenitic Stainless Steels

Welding procedures used for welding and overlaying austenitic stainless steels do not require any hardness surveys or hardness testing to verify hardness in the HAZ. 2.6 Specific Austenitic Stainless Steel Grades

2.6.1 Austenitic stainless steel UNS S20910 shall be in the solution-annealed, hot-rolled (hot/cold-worked), or cold-worked condition. The hardness shall not exceed 35 HRC.

2.6.2 Welding procedures used for welding and overlaying UNS S20910 do not require any hardness surveys or hardness testing to verify hardness in the HAZ. 2.7 Highly Alloyed Austenitic Stainless Steels

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2.7.2 The chemical composition requirements for the highly alloyed austenitic stainless steels are as follows:

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2.7.1 Highly alloyed austenitic stainless steels shall meet the chemical composition requirements specified in Paragraph 2.7.2 and shall be in the solution-annealed condition or solution-annealed and cold-worked condition. The hardness shall not exceed 35 HRC. Free-machining highly alloyed austenitic stainless steels are not allowed.

%Ni + (2 x %Mo) > 30 and Mo > 2% or Pitting Resistance Equivalent Number (PREN) > 40%

Where PREN is determined as shown in Equation (1): PREN = %Cr + 3.3 (%Mo + 0.5 × %W) + 16 × %N

(1)

NOTE: For the purposes of this standard, PREN is used only to identify a group of alloys from a chemical composition standpoint. Use of PREN to predict relative corrosion resistance is outside the scope of this standard. 2.7.3 Welding procedures used for welding and overlaying the highly alloyed austenitic stainless steels do not require any hardness surveys or hardness testing to verify hardness in the HAZ.

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MR0103-2012 2.8 Duplex Stainless Steel Materials 2.8.1 Wrought and cast duplex stainless steel products shall be in the solution-annealed and liquid-quenched condition. Tubing shall be rapidly cooled by liquid quenching, or by air or inert gas cooling to below 315 °C (600 °F). The ferrite content shall be 35 to 65 vol%. Aging heat treatments to increase strength and/or hardness are prohibited because of the formation of embrittling phases. (10)

2.8.1.1 The hardness of grades with PREN ≤ 40% according to Equation (1) shall not exceed 28 HRC.

(10)

2.8.1.2 The hardness of grades with PREN > 40% according to Equation (1) shall not exceed 32 HRC.

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2.8.2 Welding of Duplex Stainless Steels

2.8.2.1 Fabrication and repair welds in all wrought and cast duplex stainless steels shall be produced using a welding procedure qualified by performing the following tests on specimens taken from the WPQT coupon(s):

2.8.2.1.1 A hardness survey shall be performed in accordance with Appendix C. The average hardness shall not exceed 310 HV, and no individual reading shall exceed 320 HV. 19

2.8.2.1.2 Metallographic ferrite measurements shall be performed in accordance with ASTM E562. The average ferrite content in the weld deposit and HAZ shall be within the range of 35 to 65%, with a relative accuracy of 10% or lower.

2.8.2.1.3 Technical considerations for qualification of welding procedures for duplex stainless steels are included in Appendix D (nonmandatory). 2.9 Precipitation-Hardenable Stainless Steel Materials

2.9.1 Austenitic precipitation-hardenable stainless steel with chemical composition in accordance with UNS S66286 shall be in either the solution-annealed and aged or solution-annealed and double-aged condition. The hardness shall not exceed 35 HRC.

2.9.2 UNS S17400 and UNS S15500 wrought martensitic precipitation-hardenable stainless steels shall be in either the H1150D condition (heat treated in accordance with Paragraph 2.9.2.2) or H1150M condition (heat treated in accordance with 20 Paragraph 2.9.2.3). The hardness shall not exceed 33 HRC. ASTM A747 CB7Cu-1 and CB7Cu-2 castings shall be in the H1150 DBL condition (heat treated in accordance with Paragraph 2.9.2.2). The hardness shall not exceed 310 HBW (30 HRC). Precipitation-hardenable martensitic stainless steels that are in accordance with this standard have provided satisfactory field service in some sour environments. These materials may, however, exhibit threshold stress levels in NACE Standard TM0177 laboratory tests that are lower than those of other materials included in this standard.

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(a) UNS S17400 and UNS S15500 shall not be used for pressure-retaining bolting applications in the doubleH1150 condition.

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2.9.2.1 The following restrictions apply to UNS S17400 and UNS S15500 when these materials are used for pressureretaining bolting:

(b) When UNS S17400 or UNS S15500 is used for pressure-retaining bolting in the H1150M condition, the hardness shall not exceed 29 HRC.

2.9.2.2 Double-H1150 (H1150D, H1150 DBL) Heat-Treatment Procedure (a) Solution anneal at 1,038 ± 14 °C (1,900 ± 25 °F) and air cool, or suitable liquid quench, to below 32 °C (90 °F). (b) Harden at 621 ± 14 °C (1,150 ± 25 °F) for 4 h minimum at temperature and cool in air to below 32 °C (90 °F). ___________________________ Brinell hardness measurements obtained on duplex stainless steels cannot be converted to Rockwell C hardness values using existing tables in ASTM E140. Use of empirically derived tables for this hardness conversion is subject to the approval of the user. (10)

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MR0103-2012 (c) Harden at 621 ± 14 °C (1,150 ± 25 °F) for 4 h minimum at temperature and cool in air. (d) Additional cycles at 621 ± 14 °C (1,150 ± 25 °F) may be used if required to produce the specified hardness level. 2.9.2.3 H1150M Heat-Treatment Procedure (a) Solution anneal at 1,038 ± 14 °C (1,900 ± 25 °F) and air cool, or suitable liquid quench, to below 32 °C (90 °F).

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(b) Harden at 760 ± 14 °C (1,400 ± 25 °F) for 2 h minimum at temperature and cool in air to below 32 °C (90 °F) before the second precipitation-hardening step. (c) Precipitation harden at 621 ± 14 °C (1,150 ± 25 °F) for 4 h minimum at temperature and cool in air. (d) Additional cycles at 621 ± 14 °C (1,150 ± 25 °F) may be used if required to produce the specified hardness level.

2.9.3.1 Two-Step Heat-Treatment Procedure (a) Solution anneal.

2.9.3 Wrought UNS S45000 martensitic precipitation-hardenable stainless steel shall be heat treated in accordance with the following two-step heat-treatment procedure. The hardness shall not exceed 31 HRC.

(b) Precipitation harden at 621 °C (1,150 °F) for a minimum of 4 h.

2.9.4 Weldments in precipitation-hardenable stainless steels shall be produced using a weld procedure qualified by performing a hardness survey in accordance with Appendix C on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness in accordance with Table 4. Welding shall not be performed on UNS S17400 and UNS S15500 bolting.

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IS N

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Table 4 Maximum Hardness Requirements for Weldments in Precipitation-Hardenable Stainless Steels Alloy(s) UNS S66286 UNS S17400, UNS S15500 UNS J92200 (CB7Cu-1), UNS J92110 (CB7Cu-2) UNS S45000

Maximum Hardness 345 HV 10 327 HV 10 302 HV 10 (HAZ) 327 HV 10 (weld deposit) 310 HV 10

_________________________________________________________________________ Section 3: Nonferrous Materials

3.1 Nickel Alloys 3.1.1 Solid-Solution Nickel Alloys 3.1.1.1 Wrought or cast solid-solution nickel-chromium-molybdenum alloys with compositions as specified in Paragraph 3.1.1.1.1 shall be in the solution-annealed condition. 3.1.1.1.1 The chemical composition requirements for the solid-solution nickel-chromium-molybdenum alloys are: 19.0% Cr minimum, 29.5% Ni + Co minimum, and

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MR0103-2012 2.5% Mo minimum. or 14.5% Cr minimum, 52% Ni + Co minimum, and 12% Mo minimum. 3.1.1.2 Wrought UNS N06600 shall not exceed 35 HRC. 3.1.1.3 Wrought UNS N08800 shall not exceed 35 HRC.

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3.1.1.4 Only those solid-solution nickel-chromium-molybdenum alloys listed in Table 5 shall be used in the cold-worked condition. The other requirements specified in Table 5 shall also be met.

Table 5 Cold-Worked Nickel-Chromium-Molybdenum Alloys and Maximum Hardness Requirements

Maximum Hardness 35 HRC 40 HRC 35 HRC 40 HRC 39 HRC 35 HRC 35 HRC

Previous Condition -Solution-Annealed -Solution-Annealed --Solution-Annealed

UNS Number N06002 N06022 N06625 N06686 N06985 N08825 N10276

3.1.1.5 Wrought UNS N04400 and N04405, and cast ASTM A49421 Grades M35-1, M35-2, and M30C shall not exceed 35 HRC.

3.1.1.6 Welding procedures used for welding and overlaying the solid-solution nickel alloys do not require any hardness surveys or hardness testing to verify hardness in the HAZ. 3.1.2 Precipitation-Hardenable Nickel Alloys

3.1.2.1 Only those precipitation-hardenable nickel alloys listed in Table 6 are allowed. corresponding maximum hardness requirements listed in Table 6 shall be met.

The conditions and

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3.1.2.2 Weldments in precipitation-hardenable nickel alloys shall be produced using a weld procedure qualified by performing a hardness survey in accordance with Appendix C on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness in accordance with Table 6.

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MR0103-2012 Table 6 Precipitation-Hardenable Nickel Alloys, Conditions, and Maximum Hardness Requirements

N07716 N07718 N07725 N07750 N07773 N07924 N09777 N09925

Solution-annealed and aged at 760 to 871 °C (1,400 to 1,600 °F) for a maximum of 4 h. Solution-annealed and aged Hot compacted powder, solution-annealed (927 C [1,700 F] min) and aged (538 to 816 C [1,000 to 1,500 F]), max tensile strength 1,380 MPa (200 ksi) Solution-annealed and aged Solution-annealed or hot-worked or hot-worked and aged Solution-annealed and aged or cast, solution-annealed, and aged Solution-annealed and aged Solution-annealed or solution-annealed and aged or hot worked or hotworked and aged Solution-annealed and aged Solution-annealed and aged Solution-annealed and aged Cold-worked or solution-annealed Solution-annealed and aged Cold-worked and aged or hot-finished and aged Cast, solution-annealed, and aged

40 HRC (382 HV)

35 HRC (335 HV)

40 HRC (382 HV) 40 HRC (382 HV)

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N07048 N07626

Maximum Hardness 35 HRC (335 HV)

N07031

Condition(s) Hot-worked and age-hardened or solution-annealed or solutionannealed and age-hardened Solution-annealed

UNS Number N05500

43 HRC (416 HV) 35 HRC (335 HV) 40 HRC (397 HV) 43 HRC (416 HV) 35 HRC (335 HV) 40 HRC (382 HV) 35 HRC (335 HV) 40 HRC (382 HV) 35 HRC (335 HV) 38 HRC (362 HV) 40 HRC (382 HV) 35 HRC (335 HV)

3.2 Cobalt-Nickel-Chromium-Molybdenum Alloys 22

3.2.1 UNS R30003, UNS R30004, UNS R30035, and BS 2HR 3 below.

shall not exceed 35 HRC except as otherwise noted

3.2.1.1 Welding requirements for UNS R30003, UNS R30004, UNS R30035, and BS 2HR 3 are outside the scope of this standard. Welding requirements shall be in accordance with the agreement between the end user (or the end user’s agent) and the manufacturer.

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3.2.2 UNS R30035 is allowed in the cold-reduced and high-temperature aged heat-treated condition in accordance with one of the aging treatments listed in Table 7. The hardness shall not exceed 51 HRC.

Table 7 UNS R30035 Heat Treatments Minimum Time (h) 4 4 6 4 2 1

Temperature 704 °C (1,300 °F) 732 °C (1,350 °F) 774 °C (1,425 °F) 788 °C (1,450 °F) 802 °C (1,475 °F) 816 °C (1,500 °F)

3.2.3 Wrought UNS R31233 shall be in the solution-annealed condition. The hardness shall not exceed 33 HRC. 3.2.3.1 Welding procedures used for welding UNS R31233 do not require any hardness surveys or hardness testing to verify hardness in the HAZ. 3.3 Cobalt-Nickel-Chromium-Tungsten Alloys UNS R30605 shall not exceed 35 HRC.

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MR0103-2012 3.4 Titanium Alloys 3.4.1 Specific guidelines must be followed for successful applications of each titanium alloy specified in this standard. For example, hydrogen embrittlement of titanium alloys may occur if these alloys are galvanically coupled to certain active metals (e.g., carbon steel) in H2S-containing aqueous media at temperatures greater than 80 °C (176 °F). Hardness has not been shown to correlate with susceptibility to SSC, but has been included for alloys with high strength to indicate the maximum testing levels at which failure has not occurred. 3.4.2 Only those titanium alloys listed in Table 8 are allowed. The conditions and corresponding maximum hardness requirements listed in Table 8 shall be met.

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Table 8 Titanium Alloys, Conditions, and Maximum Hardness Requirements Condition(s)

R50400 R53400 R56260 R56323 R56403 R56404 R58640

None specified Annealed at 774  14 C (1,425  25 F) for 2 h, air cool Annealed or solution-annealed or solution-annealed and aged Annealed Annealed Annealed Annealed

Maximum Hardness 100 HRBS 92 HRBS 45 HRC 32 HRC 36 HRC 35 HRC 42 HRC

UNS Number

3.4.3 Welding requirements for titanium alloys are outside the scope of this standard. Welding requirements shall be in accordance with the agreement between the end user (or the end user’s agent) and the manufacturer. 3.5 Aluminum Alloys

3.5.1 Aluminum alloys are allowed because they are not susceptible to SSC. However, they can suffer corrosion when exposed outside the pH range of about 4.0 to 8.5 and also pitting corrosion if chloride ions are present.

3.6 Copper Alloys

3.5.2 Welding procedures used for welding aluminum alloys do not require any hardness surveys or hardness testing to verify hardness in the HAZ.

3.6.1 Copper alloys are allowed because they are not susceptible to SSC. However, they can suffer corrosion because of the sulfides and also stress corrosion cracking if NH3 is present, as often noted in sour refinery environments.

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3.6.2 Welding procedures used for welding copper alloys do not require any hardness surveys or hardness testing to verify hardness in the HAZ.

Section 4: General Fabrication Requirements

4.1 Materials and fabrication processes shall meet the requirements of this section. 4.2 Overlays 4.2.1 Tungsten-carbide alloys and ceramics are allowed as overlays. Following application of the overlay, the base material shall meet the hardness requirement for that base metal specified in the pertinent paragraph in Section 2 or 3. 4.2.2 Joining of dissimilar materials, such as cemented carbides to alloy steels by silver brazing, is allowed. After brazing, the base material shall meet the hardness requirement for that base metal specified in the pertinent paragraph in Section 2 or 3.

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MR0103-2012 4.2.3 The base materials listed in Sections 2 and 3 are also allowed as weld overlays, provided they meet the provisions of their respective paragraphs after being applied as overlays. Following application of the overlay, the base material shall meet the hardness requirement for that base metal specified in the pertinent paragraph in Section 2 or 3. (11)

4.2.4 Overlays of cobalt-chromium-tungsten, nickel-chromium-boron, and nickel-boron (see SAE AMS4779 ) hardfacing alloys are allowed. Following application of the overlay, the base material shall meet the hardness requirement for that base metal specified in the pertinent paragraph in Section 2 or 3. 4.3 Welding

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4.3.1 All weldments shall meet the general requirements listed in this section (Paragraph 4.3). Specific welding requirements are provided for some materials in the pertinent material paragraphs in Section 2 or 3, in which case those requirements shall also be met. In cases in which the specific welding requirements conflict with the requirements of this section, the specific material welding requirements shall override these general requirements. 4.3.2 Welders and welding procedures shall be qualified in accordance with AWS, industry codes.

(12)

API, ASME, or other appropriate

4.3.3 Dissimilar-metal welds, such as welds produced using filler metals that are more noble than the base metal and/or welds in which the two base metals are different, shall meet the following requirements: 4.3.3.1 The weld metal shall be closely equivalent in chemistry and properties to a base material that is allowed according to this standard.

4.3.3.2 If a Vickers hardness survey is required to be performed during weld procedure qualification for either base metal, or for a base metal that is equivalent to the deposited weld metal, a Vickers hardness survey in accordance with Appendix C shall be performed on a specimen taken from the WPQT coupon(s) to demonstrate the ability of the procedure to produce weldments that meet the specified hardness. The hardness criteria for each portion of the weldment shall be as specified in the pertinent material paragraph in Section 2 or 3 for that base metal, or, in the case of deposited weld metal, for the base metal that is equivalent to the deposited weld metal.

4.4 Cladding on Carbon Steels, Alloy Steels, and Martensitic Stainless Steels

4.4.1 For the purpose of this standard, cladding is defined as a metallurgically bonded layer of a corrosion-resistant alloy material applied to the entire wetted surface of a substrate material that is relatively less corrosion-resistant. 4.4.2 Allowed fabrication methods used for cladding include hot rolling, explosion bonding, and weld overlaying.

4.4.3 Cladding materials shall be selected from Section 2 or 3 of this standard, and shall meet all requirements for the selected alloy(s) specified in the pertinent paragraph(s).

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(a) Relative SSC resistance of the cladding material;

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4.4.4 A number of factors influence the SSC resistance of clad components, including, but not limited to:

(b) Corrosion resistance of the clad layer in the process environment (which affects the rate of hydrogen production); (c) Hydrogen diffusion rate in the clad layer; (d) Soundness of the clad layer; (e) Relative SSC resistance of the substrate material; (f)

Fabrication methods used at junctions between neighboring clad components;

(g) Fabrication methods used at junctions between clad components and neighboring unclad components; and ____________________________ (11) (12)

SAE International (SAE), 400 Commonwealth Drive, Warrendale, PA 15096-0001. American Welding Society (AWS), 550 N.W. LeJeune Road, Miami, Florida 33126.

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MR0103-2012 (h) Galvanic effects (if the substrate material becomes exposed or at junctions with neighboring unclad components). 4.4.5 Evaluation of these and other factors is outside the scope of this standard. Therefore, the end user shall specify whether or not the substrate material must meet the requirements of this standard. 4.5 Identification Stamping 4.5.1 Identification stamping using low-stress (dot, vibratory, and round V) stamps is allowed.

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4.5.2 Conventional sharp V stamping is allowed in low-stress areas, such as the outside diameter of flanges. Sharp V stamping is not allowed in high-stress areas unless the item receives a subsequent thermal treatment to reduce the hardness to meet the maximum hardness requirement for the base metal specified in the applicable sections of this standard. 4.6 Threading 4.6.1 Machine-Cut Threads Machine-cut threading processes are allowed.

4.6.2 Cold-Formed (Rolled) Threads

After threads have been cold formed, the threaded component shall meet the heat-treatment conditions and hardness requirements specified in either Section 2 or 3 for the parent alloy from which the threaded component was fabricated.

4.7 Cold-Deformation Processes

4.7.1 Cold-deformation processes such as burnishing that do not impart cold work exceeding that incidental to normal machining operations (such as turning or boring, rolling, threading, and drilling) are allowed.

4.7.2 Cold deformation by controlled shot peening is permitted when applied to base materials that meet the requirements of this standard, and when limited to the use of a maximum shot size of 2.0 mm (0.080 in) and a maximum of 10C Almen 24 intensity. The process shall be controlled in accordance with SAE AMS2430.

_________________________________________________________________________ Section 5: Bolting

5.1 Materials used for bolting and fasteners that are exposed to sour environments (see Paragraph 1.3) shall meet the requirements of this section. The user shall be responsible for specifying whether bolting is exposed or unexposed in accordance with Paragraphs 5.2 and 5.3. 5.2 Exposed Bolting

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5.2.1 Bolting that is exposed directly to the sour environment shall meet the requirements of Section 2 or Section 3. 5.2.1.1 External bolting and fasteners used underground, covered with insulation, equipped with flange protectors, or otherwise denied direct atmospheric exposure, and that are used on equipment that contains a sour environment, shall be considered exposed to a sour environment, and shall meet the requirements of Section 2 or Section 3. 5.2.1.2 Users and designers should be aware that it may be necessary to de-rate the strength of the joint and the pressure rating of the equipment in some cases when using bolting that meets these requirements. 5.2.1.3 Special restrictions apply to UNS S17400 and UNS S15500 when these alloys are used for pressure-retaining bolting. (See Paragraph 2.9.2.1.) 5.2.1.4 The bolting and nut materials listed in Table 9 were specifically established to meet the requirements of Section 2 or Section 3. Other materials meeting the requirements of Section 2 or Section 3 are also allowed. 5.2.1.5 Zinc or cadmium coatings should not be used on bolts, nuts, cap screws, or other fasteners in sour environments. These coatings enhance the generation of hydrogen on the surface and can contribute to hydrogen cracking.

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MR0103-2012 5.3 Unexposed Bolting 25

5.3.1 Unexposed bolting and fasteners may be furnished to applicable standards such as ASTM A193, A194, and 27 A320. To be considered “unexposed,” the bolting must be used externally on flanges or other parts that are not directly exposed to sour environments, and must be directly exposed to the atmosphere at all times (see Paragraph 5.2.1.1).

Table 9 Common Bolting Materials That Meet Section 2 and Section 3 Requirements Material Specification ASTM A193 Grade B7M ASTM A193 Grade B8MA, Class 1A ASTM A320 Grade L7M ASTM A194 Grade 2HM ASTM A194 Grade 7M ASTM A194 Grade 8MA

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Bolting Component Bolt, Stud, Cap Screw

Nut

_________________________________________________________________________ Section 6: Plating, Coatings, and Diffusion Processes

6.1 Metallic coatings (electroplated or electroless), conversion coatings, and plastic coatings or linings are not allowed for preventing SSC of base metals. The use of such coatings for any other purpose (such as wear resistance or corrosion resistance) is outside the scope of this standard. 6.2 Nitriding is an allowed surface diffusion treatment when performed at a temperature below the lower critical temperature of the material being treated. Its use as a means of preventing SSC is not allowed.

_________________________________________________________________________

Section 7: Special Components

7.2 Bearings

7.1 Materials for special components including instrumentation, control devices, seals, bearings, and springs shall meet the requirements of this section if they are directly exposed to sour environments during normal operation of the device. Paragraph 1.2 provides guidelines to determine the applicability of the standard to specific uses.

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7.2.2 Nickel-chromium-molybdenum-tungsten alloy UNS N10276 is allowed for bearing pins (e.g., core roll pins) in the coldworked condition. The hardness shall not exceed 45 HRC.

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7.2.1 Bearings directly exposed to sour environments shall be made from materials that meet the requirements in Section 2 or Section 3, except as noted in Paragraph 7.2.2. Bearings made from other materials must be isolated from the sour environment to function properly.

7.3 Springs

7.3.1 Springs directly exposed to the sour environment shall be made from materials that meet the requirements in Section 2 or Section 3, except as noted in Paragraphs 7.3.2, 7.3.3, and 7.3.4. 7.3.2 Cobalt-nickel-chromium-molybdenum alloy UNS R30003 is allowed for springs in the cold-worked and age-hardened condition. The hardness shall not exceed 60 HRC. UNS R30035 is allowed for springs in the cold-worked and agehardened condition when aged for a minimum of 4 h at a temperature no lower than 649 °C (1,200 °F). The hardness shall not exceed 55 HRC. 7.3.3 Nickel-chromium alloy UNS N07750 is allowed for springs in the cold-worked and age-hardened condition. The hardness shall not exceed 50 HRC. 7.3.4 UNS N07090 is allowed for springs for compressor valves in the cold-worked and age-hardened condition. The hardness shall not exceed 50 HRC.

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MR0103-2012 7.4 Instrumentation and Control Devices 7.4.1 Instrumentation and control device components directly exposed to sour environments shall be made from materials that meet the requirements in Section 2 or Section 3. 7.4.1.1 UNS S31600 austenitic stainless steel, highly alloyed austenitic stainless steel (see Paragraph 2.7), or nickel alloy (see Paragraph 3.1) materials are allowed for compression fittings, screen devices, and instrument or control tubing even though these components may not satisfy the requirements stated for those materials in Section 2 or Section 3.

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7.4.2 Diaphragms, Pressure-Measuring Devices, and Pressure Seals 7.4.2.1 Diaphragms, pressure-measuring devices, and pressure seals directly exposed to a sour environment shall be made from materials that meet the requirements in Section 2 or Section 3, except as noted in Paragraphs 7.4.2.2, 7.4.2.3, and 7.4.2.4. 7.4.2.2 Cobalt-nickel-chromium-molybdenum alloys UNS R30003 and UNS R30004 are allowed for diaphragms, pressure-measuring devices, and pressure seals. The hardness shall not exceed 60 HRC.

7.4.2.3 Cobalt-nickel-chromium-molybdenum-tungsten alloy UNS R30260 is allowed for diaphragms, pressuremeasuring devices, and pressure seals. The hardness shall not exceed 52 HRC.

7.4.2.4 Pressure seals shall comply with the material requirements in Section 2 or Section 3 or may be manufactured of wrought cobalt-chromium-nickel-molybdenum alloy UNS R30159 with the primary load-bearing or pressure-containing direction parallel to the longitudinal or rolling direction of wrought product. The hardness shall not exceed 53 HRC. 7.4.3 Wrought UNS N08904 is allowed for use as instrument tubing in the annealed condition. The hardness shall not exceed 180 HV 10.

7.5 Seal Rings and Gaskets 7.5.1 Seal rings directly exposed to a sour environment shall be made from materials that meet the requirements in Section 2 or Section 3. 28

7.6 Snap Rings

7.5.2 Austenitic stainless steel API compression seal rings and gaskets made of wrought or centrifugally cast ASTM A351 Grade CF8 or CF8M chemical compositions are allowed in the as-cast or solution-annealed condition. The hardness shall not exceed 160 HBW (83 HRBS).

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7.6.2 Precipitation-hardenable stainless steel alloy UNS S15700 originally in the RH950 solution-annealed and aged condition is allowed for snap rings when further heat treated in accordance with the three-step heat treatment procedure below. The hardness shall be 30 to 32 HRC.

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7.6.1 Snap rings directly exposed to a sour environment shall be made from applicable materials that meet the requirements in Section 2 or Section 3, except as noted in Paragraph 7.6.2.

7.6.2.1 Heat-treatment procedure (three-step process) shall be: (a) Temper at 621 °C (1,150 °F) for 4 h, 15 min. Cool to room temperature in still air. (b) Temper at 621 °C (1,150 °F) for 4 h, 15 min. Cool to room temperature in still air. (c) Temper at 566 °C (1,050 °F) for 4 h, 15 min. Cool to room temperature in still air.

7.7 Special Process Parts 7.7.1 Cobalt-chromium-tungsten and nickel-chromium-boron alloys, whether cast, powder-metallurgy processed, or thermomechanically processed, are allowed.

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MR0103-2012 7.7.2 Tungsten-carbide alloys, whether cast or cemented, are allowed.

_________________________________________________________________________ Section 8: Valves 8.1 Valves shall meet the requirements of this section if they are to be exposed to sour environments (see Paragraph 1.3). A common failure mode of gate valves exposed to sour environments and not fabricated with hardness-controlled components is a dropped gate, rendering the valve inoperable.

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8.2 Valves (new or reconditioned), including internal components, shall be manufactured or remanufactured from materials that meet the requirements in Section 2 or Section 3.

_________________________________________________________________________ Section 9: Compressors and Pumps

9.1 Compressor and pump components that are to be exposed to sour environments (see Paragraph 1.3) shall be manufactured from materials that meet the requirements in Section 2 or Section 3, except as noted in Paragraphs 9.2 and 9.3. 29

9.2 ASTM A278 Class 35 or 40 gray cast iron and ASTM A395 ductile iron are allowed as compressor cylinders, liners, pistons, 30 and valves. Aluminum alloy ASTM B26 A03550-T7 is allowed for pistons. Aluminum, soft carbon steel, and soft, low-carbon iron are allowed as gaskets in compressors handling sour gas.

9.3 UNS G43200 and a modified version of UNS G43200 that contains 0.28 to 0.33% carbon are allowed for compressor impellers at a maximum yield strength of 620 MPa (90 ksi) provided they have been heat treated in accordance with Paragraph 9.3.1. 9.3.1 Heat-Treatment Procedure (Three-Step Process)

9.3.1.1 Austenitize and quench. 9.3.1.2 Temper at 621 °C (1,150 °F) minimum, but below the lower critical temperature. Cool to ambient temperature before the second temper.

9.3.1.3 Temper at 621 °C (1,150 °F) minimum, but lower than the first tempering temperature. Cool to ambient temperature.

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References

1. NACE MR0175/ISO 15156 (latest revision), “Petroleum and natural gas industries—Materials for use in H2S-containing environments in oil and gas production” (Houston, TX: NACE).

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2. NACE SP0296 (formerly RP0296) (latest revision), “Detection, Repair, and Mitigation of Cracking in Refinery Equipment in Wet H2S Environments” (Houston, TX: NACE). 3. NACE Publication 8X194 (latest revision), “Materials and Fabrication Practices for New Pressure Vessels Used in Wet H2S Refinery Service” (Houston, TX: NACE). 4. NACE Publication 8X294 (latest revision), “Review of Published Literature on Wet H2S Cracking of Steels Through 1989” (Houston, TX: NACE). 5. ASME Boiler and Pressure Vessel Code, Section IX (latest revision), “Welding and Brazing Qualifications” (New York, NY: ASME). 6. NACE SP0472 (formerly RP0472) (latest revision), “Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments” (Houston, TX: NACE).

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MR0103-2012 7. NACE Standard TM0177 (latest revision), “Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking and Stress Corrosion Cracking in H2S Environments” (Houston, TX: NACE). 8. ASTM E140 (latest revision), “Standard Hardness Conversion Tables for Metals—Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, and Scleroscope Hardness” (West Conshohocken, PA: ASTM). 9.

ISO 18265 (latest revision), “Metallic Materials - Conversion of Hardness Values” (Geneva, Switzerland: ISO).

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10. ASTM E384 (latest revision), “Standard Test Method for Knoop and Vickers Hardness of Materials” (West Conshohocken, PA: ASTM). 11. ASTM A833 (latest revision), “Standard Practice for Indentation Hardness of Metallic Materials by Comparison Hardness Testers” (West Conshohocken, PA: ASTM). 12. ASTM A941 (latest revision), “Standard Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys” (West Conshohocken, PA: ASTM).

13. ASTM A53/A53M (latest revision), “Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless” (West Conshohocken, PA: ASTM). 14. ASTM A106/A106M (latest revision), “Standard Specification for Seamless Carbon Steel Pipe for High-Temperature Service” (West Conshohocken, PA: ASTM).

15. API Spec 5L (latest revision), “Specification for Line Pipe” (Washington, DC: API). 16. ASME B31.3 (latest edition), “Process Piping” (New York, NY: ASME).

17. ANSI/NBBPVI NB-23, “National Board Inspection Code” (Columbus, Ohio: NBBPVI).

18. ASTM A395/A395M (latest revision), “Standard Specification for Ferritic Ductile Iron Pressure-Retaining Castings for Use at Elevated Temperatures” (West Conshohocken, PA: ASTM).

19. ASTM E562 (latest revision), “Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count” (West Conshohocken, PA: ASTM). 20. ASTM A747/A747M (latest revision), “Standard Specification for Steel Castings, Stainless, Precipitation Hardening” (West Conshohocken, PA: ASTM).

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22. BS 2HR 3 (latest revision), “Specification for Nickel-Cobalt-Chromium-Molybdenum-Aluminium-Titanium Heat-Resisting Alloy Billets, Bars, Forgings and Parts (Nickel Base, Co 20, Cr 14.8, Mo 5, Al 4.7, Ti 1.2)” (London, U.K: BSI).

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21. ASTM A494/A494M (latest revision), “Standard Specifications for Castings, Nickel and Nickel Alloy” (West Conshohocken, PA: ASTM).

23. SAE AMS4779 (latest revision), “Nickel Alloy, Brazing Filler Metal, 94Ni - 3.5Si - 1.8B, 1,800 to 1,950 °F (982 to 1,066 °C) Solidus-Liquidus Range” (Warrendale, PA: SAE). 24. SAE AMS2430 (latest revision), “Shot Peening, Automatic” (Warrendale, PA: SAE). 25. ASTM A193/A193M (latest revision), “Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature or High Pressure Service and Other Special Purpose Applications” (West Conshohocken, PA: ASTM). 26. ASTM A194/A194M (latest revision), “Standard Specification for Carbon and Alloy Steel Nuts for Bolts for High Pressure or High Temperature Service, or Both” (West Conshohocken, PA: ASTM). 27. ASTM A320/A320M (latest revision), “Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for LowTemperature Service” (West Conshohocken, PA: ASTM). 28. ASTM A351/A351M (latest revision), “Standard Specification for Castings, Austenitic, for Pressure-Containing Parts” (West Conshohocken, PA: ASTM).

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MR0103-2012 29. ASTM A278/A278M (latest revision), “Standard Specification for Gray Iron Castings for Pressure-Containing Parts for Temperatures Up to 650 °F (350 °C)” (West Conshohocken, PA: ASTM). 30. ASTM B26/B26M (latest revision), “Standard Specification for Aluminum-Alloy Sand Castings” (West Conshohocken, PA: ASTM). nd

31. W.M. Haynes, ed. CRC Handbook of Chemistry and Physics, 72 ed. (Cleveland, OH: CRC Press, 1986). 32. ASTM E18 (latest revision), “Standard Test Methods for Rockwell Hardness of Metallic Materials” (West Conshohocken, PA: ASTM).

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33. ISO 6508-1 (latest revision), “Metallic materials — Rockwell hardness test — Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T)” (Geneva, Switzerland: ISO). 34. ASTM E10 (latest revision), “Standard Test Method for Brinell Hardness of Metallic Materials” (West Conshohocken, PA: ASTM). 35. ISO 6506-1 (latest revision), “Brinell hardness test — Part 1: Test method” (Geneva, Switzerland: ISO).

36. ASTM E92 (withdrawn), “Standard Test Method for Vickers Hardness of Metallic Materials” (West Conshohocken, PA: ASTM). 37. ISO 6507-1 (latest revision), “Vickers hardness test — Part 1: Test method” (Geneva, Switzerland: ISO).

38. ASTM A956 (latest revision), “Standard Test Method for Leeb Hardness Testing of Steel Products” (West Conshohocken, PA: ASTM). 39. ASTM A1038 (latest revision), “Standard Test Method for Portable Hardness Testing by the Ultrasonic Contact Impedance Method” (West Conshohocken, PA: ASTM

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41. DIN

40. ASTM E110 (latest revision), “Standard Test Method for Indentation Hardness of Metallic Materials by Portable Hardness Testers” (West Conshohocken, PA: ASTM). 50156-1 (latest revision), “Metallic materials - Leeb Hardness Test - Part 1: Test Method” (Berlin, Germany: DIN).

42. API TR 938-C (latest revision), “Use of Duplex Stainless Steels in the Oil Refining Industry” (Washington, DC: API).

43. ASTM A995/A995M (latest revision), “Standard Specification for Castings, Austenitic-Ferritic (Duplex) Stainless Steel, for Pressure-Containing Parts” (West Conshohocken, PA: ASTM). 44. ASME SFA-5.4/SFA-5.4M (latest revision), “Stainless Steel Electrodes for Shielded Metal Arc Welding” (New York, NY: ASME).

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46. ASTM E1245 (latest revision), “Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis” (West Conshohocken, PA: ASTM).

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45. ASME SFA-5.9/SFA-5.9M (latest revision), “Bare Stainless Steel Welding Electrodes and Rods” (New York, NY: ASME).

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47. ISO/IEC 17025 (latest revision), “General requirements for the competence of testing and calibration laboratories” (Geneva, Switzerland: ISO). 48. ASTM A923 (latest revision), “Standard Test Methods for Detecting Detrimental Intermetallic Phase in Duplex Austenitic/Ferritic Stainless Steels” (West Conshohocken, PA: ASTM). 49. ASTM G48 (latest revision), “Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution” (West Conshohocken, PA: ASTM).

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Deutsches Institut fur Normung (DIN), Burggrafenstrasse 6, D-10787 Berlin, Germany. International Electrotechnical Commission (IEC), 3 rue de Varembe, P.O. Box 131, CH-1211 Geneva 20, Switzerland.

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MR0103-2012 _________________________________________________________________________ Appendix A Sulfide Species Plot (Nonmandatory)

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The plot in Figure A1 shows sulfide species as a function of pH. This plot was constructed based on the equilibrium constants for nd 31 H2S in Section 8-41 of CRC Handbook of Chemistry and Physics, 72 Edition. See Paragraph 1.3.5 for further explanation.

Figure A1: Sulfide Species Plot For closed system at 25째C (77째F)

1.2 1.1

H2S(aq)

0.8

0.5

0.4 0.3

0.0 0

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S2-

0.6

0.1

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HS-

0.7

0.2

0.9

Mole Fraction of Sulfur Species

1.0

Figure A1: Sulfide Species Plot for Closed System at 25 째C (77 째F).

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MR0103-2012 _________________________________________________________________________ Appendix B Background Information on Hardness Testing and Requirements (Nonmandatory)

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B1. Accurate hardness testing requires strict compliance with the hardness test methods described in the appropriate ASTM standards. 32

B2. Rockwell hardness test methods, performed in accordance with ASTM Standard E18 or ISO 6508-1, are relatively quick, direct-reading tests, and as such they are commonly used in manufacturing environments. These hardness test methods use loads ranging from 147 N (15 kgf) to 1,470 N (150 kgf). Because of the relatively small loads that are used, the hardness indentations are small, and the measurements represent the hardness in a very localized volume of material. Therefore, these hardness test methods are very sensitive, and are suited for identifying localized hard spots. Drawbacks to these test methods are the size restrictions on components that can be tested, geometrical limitations that prevent testing in certain locations, and lack of portability.

NOTE: Beginning in the 2002 revision of ASTM E18, tungsten carbide balls are allowed for “B” scale tests in addition to the hardened steel balls that were previously required. The scale designations for Rockwell “B” hardness measurements are now “HRBS” for tests performed with a steel ball, and “HRBW” for tests performed with a tungsten carbide ball. The hardness values required in this standard are all “HRBS” values, because all testing in the past used the steel ball indenter. HRBS and HRBW test results differ because of the different mechanical properties of the two ball indenters. There are currently no standardized conversion tables available for conversion of HRBS to HRBW. 34

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B4. Comparison hardness testers (commonly, but incorrectly, referred to as portable Brinell hardness testers) use a hammer blow to simultaneously indent the component being evaluated and a test bar of known hardness. The relative indentation sizes are measured and a calculation is performed to determine the hardness of the component. Comparison hardness testers are commonly used to check field weldments. Comparison hardness testing is performed in accordance with ASTM Standard A833. The hardness values obtained using comparison hardness testers correlate directly to Brinell hardness values obtained using testing parameters discussed in Paragraph B3.

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B3. The Brinell hardness test method, performed in accordance with ASTM Standard E10 or ISO 6506-1, involves creation of an indentation, optical measurement of the indentation diameter, and calculation of the hardness value. Because of the relatively large test loads used, this test method produces a hardness value that represents an “average” of the material hardness over a relatively large volume of material. The Brinell test method is often used to measure the hardness of castings and forgings. Drawbacks to this test method are the size restrictions on components that can be tested, geometrical limitations that prevent testing in certain locations, and lack of portability. ASTM E10 now requires Brinell hardness testing to be performed with a tungsten carbide ball indenter. The symbol “HBW” denotes Brinell hardness testing performed in this manner.

B5. The macro Vickers hardness test method, performed in accordance with ASTM E384 (which has replaced ASTM E92 ) or 37 ISO 6507-1, is similar to the Brinell hardness test method except it makes use of a diamond pyramid indenter. The advantage of the Vickers hardness test method is that it provides relatively load-independent hardness values when performed with loads ranging from 0.25 N (25 gf) to 1,180 N (120 gf). It is common practice to use 49 N (5 kgf) or 98 N (10 kgf) Vickers hardness testing for welding procedure qualifications because this produces an accurate assessment of the weldment HAZ hardness. Vickers hardness criteria have been specified for a few selected welding procedure qualifications in this standard, based on proven field experience. Further details are available in NACE SP0472. Vickers hardness is designated as HV, with the test load in kgf indicated by a suffix number (e.g., 248 HV 10 denotes a Vickers hardness of 248 determined using a 10 kgf load). B6. Hardness requirements specified in this standard in HBW units are generally lower than the equivalent “acceptable” HRC values (which applies to both conventional Brinell hardness testing and comparison hardness testing) to compensate for inhomogeneity of some material forms and weld deposits and/or to account for normal variations in field and/or production hardness testing using the comparison hardness tester. B7. HRC and HRBS are cited for particular materials or product forms under the following conditions:

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MR0103-2012 (a) When the raw material specification lists a hardness requirement in HRC or HRBS; (b) When the industry standard testing method for that product form is HRC or HRBS; or (c) When the material will be tested at the component level. B8. HBW is cited for particular materials or product forms under the following conditions: (a) When the raw material specification lists a hardness requirement in HBW;

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(b) When the industry standard testing method for that product form is HBW; or (c) When the hardness requirement pertains to evaluation of weld metal hardness, which is most commonly performed using a portable Brinell hardness tester.

B9. A standard fixed-location hardness testing machine may not be capable of testing certain samples because of the sample size, weight, location, accessibility, or other requirements. In these circumstances, the use of a portable hardness tester may be the only option available. However, not all portable hardness testers meet the requirements of ISO or ASTM standard hardness test methods. A list of portable hardness test standards used for ferrous materials is provided in Table B1.

Table B1 Portable Hardness Testing Standards

Comparison hardness Leeb hardness testing Portable hardness testing by the ultrasonic contact impedance method Indentation hardness of metallic materials by portable hardness testers Leeb hardness testing

ASTM A833 38 ASTM A956 39 ASTM A1038 40 ASTM E110 41 DIN 50156-1

B10. Portable hardness testers that do not meet any of the standards listed in Table B1 are deemed to be nonstandard testing equipment and are outside the scope of this standard.

B11. There are two major types of portable hardness testers: B11.1 Portable hardness testers that follow the same test principles as those defined for a standard fixed-location hardness tester using the same test method, e.g., Brinell, Rockwell, and Vickers test methods that are included in ASTM E110.

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B12. The most common sources of error when using portable hardness testers are the alignment of the indenter to the test surface and the timing of the test forces. The user is cautioned to take all necessary measures to keep the centerline of the indenter perpendicular to the test surface and to strictly follow to the standard test method procedures.

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B11.2 Portable hardness testers that measure hardness by a means or procedure that is different from those defined for a standard fixed-location hardness tester, e.g., Brinell, Rockwell, and Vickers test methods that are included in ASTM A833, A956, A1038, and DIN 50156.

B13. Portable hardness testers are subject to damage when they are moved from one test site to another. Therefore, the user must be aware of the test method verification requirements when the portable hardness tester is new, or when adjustments, modifications, and repairs are made that could affect the application of the test forces or depth measuring system. B14. The standard requirements for verification should be followed. Verification should be performed with the device oriented in the same position(s) that are used in production. Verification should be repeated occasionally during testing and after testing is completed. B15. Precision is the closeness of agreement between test results obtained under prescribed conditions. Bias is a systematic error that contributes to the difference between the mean of a large number of test results and an accepted reference value. Portable hardness testers, in comparison to fixed-location hardness testers, inherently introduce larger precision variances and bias errors that influence the test results.

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MR0103-2012 B16. The user must understand that not all portable hardness testing standards include precision and bias rules that may be used to establish differences in test results that would be expected between portable and fixed-location instruments. B17. Precision rules, bias rules, and results differ not only between standard fixed location and portable hardness test methods, but also between standard portable hardness test methods. Consequently, the user is cautioned that all portable hardness testers should not be considered as equal and that the appropriate hardness testing standard(s) must be thoroughly reviewed and considered before its application is approved as meeting the hardness requirements in this standard for the equipment's intended service conditions.

Test material hardness: 201 HBW

RPB = 14 HBW

Test material hardness: 543 HBW

RPB = 39 HBW

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B18. For example, Equations (B1) and (B2) show ASTM E110 values of RPB (the typical amount of variation that can be expected between test results obtained for the same material by different operators using a different hardness tester on different days) at two different hardness levels. (B1) (B2)

Note: ASTM A833 is a standard practice and not a test method. Consequently, it does not contain precision and bias rules and is not capable of establishing precision variances and bias errors that may influence the test results. B19. Hardness values obtained using portable methods shall be reported in accordance with the requirements of the corresponding specification, as follows:

(a) ASTM A833 comparison hardness test result example: 197 HBC/200, where 197 is the hardness determined, HBC indicates that the hardness was obtained using the comparison hardness test, and 200 is the Brinell hardness of the comparative test bar. The manufacturerâ&#x20AC;&#x2122;s equipment and the diameters of the impressions in the test piece and comparative test bar must also be reported.

(b) ASTM A956 or DIN 50156-1 Leeb hardness test result example: 187 HB (HLG), where 187 HB is the Brinell hardness that was converted from the Leeb hardness number, and HLG indicates Leeb hardness obtained using a type G impact device.

(c) ASTM A1038 ultrasonic contact impedance hardness test result example: 250 HV (UCI) 10, where 250 HV is the Vickers hardness, UCI indicates that the hardness was measured using the ultrasonic contact impedance method, and 10 indicates that a force of 10 kgf was utilized.

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B20. Conversion of hardness values from one hardness scale to another can introduce errors. ASTM E140 and ISO 18265 include warnings regarding the limitations and risks associated with conversion of hardness values, including indications that conversions are not always precise for all materials and may even be of questionable precision, bias, and uncertainty. These limitations and risks apply to hardness conversions involving the various standard fixed-location hardness test methods as well as the various portable hardness test methods.

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(d) ASTM E110 portable indentation hardness test result example: 22 HRC/P, where 22 HRC is the hardness of 22 on Rockwell C scale, and /P indicates that the measurement was made using a portable Rockwell hardness tester.

B21. Some fixed-location and portable hardness testers perform internal conversions between hardness scales using the tables in ASTM E140 or ISO 18265. There may also be some instances in which hardness scale conversions are handled outside of the ASTM E140 or ISO 18265 tables based on proprietary data or algorithms, especially in some portable instruments where no standardized conversion tables exist. In either case, conversions may be an additional source of inaccuracy and uncertainty. B22. Both ASTM E140 or ISO 18265 contain specific rules for reporting converted hardness numbers using their tables. Examples of reporting converted hardness numbers are as follows. (a) ASTM E140: When converted hardness numbers are reported, the measured hardness and test scale shall be indicated in parentheses as in the following example: 353 HBW (38 HRC) (b) ISO 18265: Conversion results shall be reported in a manner that clearly indicates which method was used to determine the original hardness value. In addition, the relevant annex to this international standard or the table used shall be given.

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MR0103-2012 Example 1: Conversion ISO 18265 - 50.5 HRC - B.2 - HV Standard number: Conversion ISO 18265 Converted hardness value: 50.5 HRC Table used for comparison: B.2 Original hardness test method used: HV Example 2:

Conversion ISO 18265 - (62.0 ± 1.0) HRC - C.2 - HV Standard number: Conversion ISO 18265 Converted hardness value, with uncertainty: (62.0 ± 1.0) HRC Table used for comparison: C.2 Original hardness test method used: HV

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If the uncertainty of the converted value is required to be reported, it shall be reported as follows:

B23. Microhardness evaluation, performed in accordance with ASTM E384 using either the Vickers or Knoop hardness test method, may be necessary for some components that are too small to be tested by conventional (macro) hardness test methods. Microhardness testing uses loads of 9.8 N (1 kgf) or less. Microhardness testing is more sensitive than macrohardness testing methods because of the very small indentation size. Because of this sensitivity, microscopic constituents such as second phases can cause individual hardness readings that are much higher than the bulk hardness. Thus, it is more difficult to establish general acceptance criteria based on microhardness testing. Individualized microhardness test procedures and associated acceptance criteria may need to be developed for each material/component combination being evaluated.

_________________________________________________________________________

Appendix C Welding Procedure Qualification Hardness Survey Layouts (Mandatory)

C1. Hardness surveys shall be performed on a specimen taken from the WPQT coupon(s) using the Vickers hardness test method with a load of 98 N (10 kgf) or less in accordance with ASTM E384. The hardness surveys shall be performed in accordance with the layouts in Figures C1 and C2, which show hardness test locations and details, respectively, for butt welds and fillet welds.

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C2. The hardness survey in accordance with Figures C1 and C2 shall be performed at a distance (A) of 1.5 ± 0.5 mm (0.06 ± 0.02 in) from the surface. If the weld interface (also sometimes called the fusion line, which is a nonstandard term) is distinct, one of the HAZ hardness measurements shall be made at a distance (B) not to exceed 0.5 mm (0.02 in) from the weld interface. If the weld interface is not distinct, a pair of indentations shall be placed 1 mm (0.04 in) apart, straddling the apparent center of the indistinct weld interface, and equidistant from the apparent center of the indistinct weld interface. The distance (L) between hardness measurements shall be 1 mm (0.04 in) in all cases.

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MR0103-2012

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(a) Typical butt weld—single side

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IS N

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(b) Typical butt weld—double sided

(d) Typical fillet weld—double sided

Figure C1: Hardness test locations. Distance A shall be 1.5 ± 0.5 mm (0.06 ± 0.02 in) from the surface.

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MR0103-2012

BASE METAL HEAT AFFECTED ZONE

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WELD DEPOSIT

(a) Butt weldâ&#x20AC;&#x201D;in any given location in Figure C1(b).

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WELD DEPOSIT

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BASE METAL BASE METAL HEAT-AFFECTED ZONE HEAT-AFFECTED ZONE WELD METAL

(b) Fillet weld

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MR0103-2012

BASE METAL HEAT-AFFECTED ZONE

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WELD DEPOSIT

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NOTE: This hardness survey shall be performed adjacent to both surfaces of the cap and root of welds.

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Distance A shall be 1.5 ± 0.5 mm (0.06 ± 0.02 in) from surface Distance B shall be ≤ 0.5 mm (0.02 in) from weld interface Indentation C shall be ≤ 0.5 mm (0.02 in) from the weld interface and shall be 1.5 ± 0.5 mm (0.06 ± 0.02 in) from the nearest surface (see Paragraph C2). Distance L shall be 1 mm (0.04 in) between indentations

C3. Hardness surveys performed prior to the issuance of this edition of MR0103 that used the hardness survey layouts in NACE MR0175/ISO 15156 are allowed. C4. Microhardness testing using Knoop or Vickers tests with ≤ 4.9 N (500 gf) loads may be considered; however, the effects of surface preparation, etching, mounting procedures, appropriate criteria, and other details shall be reviewed and approved by the user before being used. Guidance on these hardness test techniques is given in ASTM E384. C5. Individual HAZ hardness readings exceeding the value permitted by this standard shall be considered acceptable if the average of three hardness readings taken in the equivalent HAZ profile location adjacent to the hard HAZ reading (by repolishing the existing specimen taken from that WPQT coupon or taking additional specimens from that WPQT coupon) does not exceed the values permitted by this standard and no individual hardness reading is greater than 5% above the specified value. C6. The hardness test results shall be appended to the PQR. The results shall include a sketch of the hardness test locations and corresponding results.

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MR0103-2012 _________________________________________________________________________ Appendix D Duplex Stainless Steel Welding Considerations (Nonmandatory)

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This appendix is considered nonmandatory, although it may contain mandatory language. It is intended only to provide supplementary information or guidance. The user of this standard is not required to follow, but may choose to follow, any or all of the provisions herein. D1. The metallurgical properties of duplex stainless steels are influenced by the microstructure. Ideally, the microstructure consists of an approximate 50/50 mix of ferrite and austenite, with no carbide or intermetallic precipitates (such as sigma phase). Too much ferrite reduces the toughness of the material and reduces its resistance to SSC. Too much austenite reduces the resistance to chloride stress corrosion cracking. Carbide and intermetallic precipitates reduce the general corrosion and pitting resistance and can adversely affect the toughness.

D2. The microstructure is strongly influenced by the cooling rate that occurs in the weld deposit and HAZ. A faster cooling rate promotes higher ferrite levels. A slower cooling rate promotes higher austenite levels, and can result in the formation of carbides and intermetallic precipitates. Achieving the desired microstructure is somewhat of a balancing act. The tendency to form second phases is a function of alloy content. The time-at-temperature to form intermetallic phases is shorter for the more highly alloyed superduplex grades than for the standard duplex grades. D3. Cooling Rate Considerations

D3.1 A number of factors influence the cooling rate in a weldment, and those factors should be considered when creating the WPQT coupon and writing the resulting welding procedure. Major factors that influence cooling rate include base metal thickness, preheat, interpass temperature, heat input, and filler metal size.

D3.1.1 Base Metal Thickness

D3.1.1.1 In general, a thicker base metal results in a faster cooling rate. This effect is more pronounced in thin base metals. Once the base metal achieves a certain thickness, the cooling becomes three-dimensional, and further increases in thickness do not significantly affect the cooling rate.

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D3.1.1.3 Following are suggested combined requirements for qualified base metal and weld deposit thickness. These are based on API TR 938-C recommendations, but have been expanded to include special considerations for casting weld repairs, which are outside the scope of API TR 938-C.

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D3.1.1.2 Many end user specifications impose special thickness constraints in addition to the qualified thickness ranges specified in Section IX of the ASME BPVC. Previous versions of MR0103 specified that the production base 42 metal thickness qualified is the thickness of the WPQT coupon Âą 20%. API TR 938-C recommends that the maximum thickness qualified is 1.2 times the thickness of the WPQT coupon. API TR 938-C also recommends that impact testing be required. If impact testing is imposed, the ASME BPVC Section IX supplementary essential variables, which restrict the minimum thickness qualified, would also apply.

(a) If the base metal thickness of the WPQT coupon (T) is < 38 mm (1.5 in), the minimum production base metal thickness qualified is T, and the maximum production base metal thickness qualified is 1.2T. (b) If T is â&#x2030;Ľ 38 mm (1.5 in) and â&#x2030;¤ 100 mm (4 in), the minimum production base metal thickness qualified for fabrication welds is 16 mm (0.63 in), and the maximum production base metal thickness qualified for fabrication welds is 100 mm (4 in). The maximum production base metal thickness qualified for repair welds in castings is 200 mm (8 in) provided the deposit thickness does not exceed 100 mm (4 in). (c) If T is > 100 mm (4 in), the minimum production base metal thickness qualified for fabrication welds is 38 mm (1.5 in), and the maximum production base metal thickness qualified for fabrication welds is 1.2T. The maximum production base metal thickness qualified for repair welds to castings is unlimited, provided the deposit thickness does not exceed 1.2T.

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MR0103-2012 NOTE: Although not mandatory in accordance with this standard, post-weld solution heat treatment should be 43 considered following major weld repairs in castings. Major weld repair is defined in ASTM A995. D3.1.2 Preheat 3.1.2.1 The higher the preheat temperature (which is essentially a minimum interpass temperature for all passes, including the first pass), the slower the cooling rate. D3.1.2.2 Duplex stainless steels are rarely preheated unless they are being welded under cold conditions, in which case they are generally preheated to room temperature.

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D3.1.3 Interpass Temperature

D3.1.3.1 The higher the interpass temperature (which is the maximum temperature at which any weld pass may be started), the slower the cooling rate. D3.1.3.2 The interpass temperature limits most commonly imposed on duplex stainless steels are 150 °C (300 °F) for the 22Cr-5Ni grades and 120 °C (250 °F) for the 25Cr-5Ni and 25Cr-7Ni grades.

D3.1.4 Heat Input

D3.1.4.1 Heat input (HI) in a weldment is calculated using Equation (D1) or Equation (D2):

HI = amps × volts × 60 travel speed

(D1)

Where travel speed is expressed in mm/min or in/min.

HI = amps × volts × 60 travel speed

(D2)

Where travel speed is expressed in mm/s or in/s. NOTE: Both equations produce a heat input value that is expressed in joules (J) per unit length of weld (i.e., J/mm or J/in).

D3.4.1.2 The higher the heat input, the slower the cooling rate.

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D3.1.4.4 Most metal producers publish recommended heat input ranges and other recommended welding parameters for their base metals, and most filler metal suppliers publish recommended amperage, voltage, and heat input ranges for their consumables. These recommendations should be considered when qualifying the welding procedure. In addition, API TR 938-C includes a heat input range recommendation for duplex stainless steels that matches the previous MR0103 requirement.

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D3.1.4.3 Many end-user specifications impose special heat input constraints in addition to the qualified heat input ranges specified in Section IX of the ASME BPVC. Previous editions of MR0103 specified that the production heat input range qualified is the heat input used when creating the WPQT coupon ± 10%.

D3.1.4.5 Considering that heat input is not absolutely constant, especially in manual welding processes, following are some guidelines for establishing heat input ranges in the WPS: (a) If the heat input is held constant while the WPQT coupon is being created, the minimum heat input qualified is 0.9 times HI (the heat input used to create the WPQT coupon), and the maximum heat input qualified is 1.1 times HI. (b) If the heat input for a given combination of welding process and filler metal size is varied (as a result of variations in amperage, voltage, and/or travel speed during welding of the WPQT coupon), the minimum allowable heat input qualified for that combination of process and filler metal size is 0.9HImin, where HImin is the minimum heat input used while creating the WPQT coupon. The maximum allowable heat input qualified is 1.1 HImax, where HImax is the maximum heat input used while creating the WPQT coupon.

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MR0103-2012 (c) When multiple processes and/or filler metal sizes are qualified using a single WPQT coupon, the minimum and maximum allowable heat input values for each combination of process and filler metal size should be determined in this same manner and documented as such on the resulting WPS. D3.1.5 Filler Metal Size

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D3.1.5.1 For a given level of heat input, a weld deposit produced using a smaller filler metal size generally experiences a higher level of heat input per unit volume of weld deposit compared with a weld deposit created using a larger filler metal size. This can affect the ferrite level, and as such, consideration should be given to specifying filler metal size as an essential variable, thus restricting welding procedures to the same filler metal size(s) used during welding procedure qualification. D4. Alloy Considerations D4.1 Alloy Grouping

D4.1.1 Because the more highly alloyed superduplex grades are more prone to form intermetallic phases than the standard duplex grades, consideration should be given to specifying alloy grouping as an essential variable, thus restricting welding procedures to the same alloy grouping as the material used during welding procedure qualification. Table D1 lists the base metal alloys in each grouping.

Duplex Alloy Grouping

Specified Chromium Content Falling Within the Range 21–23% Cr 24–27% Cr 24–26% Cr

Specified Nickel Content Falling Within the Range 4.5–6.5% Ni 4.5–6.5% Ni 6.0–8.0% Ni

22Cr-5Ni 25Cr-5Ni 25Cr-7Ni

Table D1 Duplex Stainless Steel Base Metal Groupings

D5. Filler Metal

NOTE: Applicable construction codes or standards may not allow welding of all materials within any one of the above groupings with one welding procedure qualification.

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D5.2 API TR 938-C includes recommended filler metals as a function of alloy grouping. In addition to those recommendations, UNS S32760 wrought products and CD3MWCuN castings, which contain intentional additions of tungsten 44 and copper, should be welded with ASME SFA-5.4 E2595 shielded metal arc welding (SMAW) filler metal, or with ASME 45 SFA-5.9 ER2594 gas tungsten arc welding (GTAW)/gas metal arc welding (GMAW) filler metal with intentional additions of tungsten and copper to essentially match the E2595 composition. These filler metals are readily available.

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D5.1 Filler metal should be selected based on the alloy being welded. Filler metals are usually over-alloyed with nickel to increase the tendency to form austenite. This is done because the weld deposit will not have the benefit of being solution annealed, which tends to reduce the ferrite content from that of the as-solidified material.

D6. Welding Procedure Qualification Testing Requirements D6.1 In addition to the standard ASME BPVC Section IX WPQT requirements (tensile and bend tests), MR0103 requires Vickers hardness survey testing and ferrite testing. Consideration should be given to performing additional tests to ensure that the weldment exhibits the necessary properties. D6.2 Vickers Hardness Survey MR0103 requires a Vickers hardness survey using a load of 98 N (10 kgf) or less. API TR 938-C specifies that a 49 N (5 kgf) load be used for the HAZ measurements. Whereas this smaller load may be able to discern a higher hardness level in a slightly narrower band adjacent to the weld fusion line, the relative size of a 49 N (5 kgf) indentation is only 30% smaller than a 98 N (10 kgf) indentation at the same hardness level. Considering the possibility of introducing errors when a hardness survey is performed using two different loads at different locations, it may be more prudent to perform all indentations using the same load, either 98 N (10 kgf) or 49 N (5 kgf).

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MR0103-2012 D6.3

Ferrite Testing

D6.3.1 MR0103 requires that ferrite testing be performed in accordance with the requirements of ASTM E562. ASTM E562 is a general point count method for estimating the relative volume of a particular phase in a microstructure. ASTM E562 does not provide specific instructions regarding the etchant to be used, nor does it provide specific requirements regarding the actual magnification to be used, the number of points in the grid, the number of fields to be examined, or the percent relative accuracy that is to be achieved. D6.3.2 Most metallographic ferrite examinations are performed after an electrolytic etch using a sodium hydroxide solution, which stains the ferrite phase.

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D6.3.3 Most end-user specifications require the use of the ASTM E562 point count method rather than the ASTM 46 E1245 automated image analysis method. There are concerns that the automated method cannot discern whether a darker region is actually ferrite, or if it is an inclusion or a second-phase particle.

CAUTION: A note at the beginning of ASTM E562 states, “This test method may be used to determine the volume fraction of constituents in an opaque specimen using a polished, planar cross section by the manual point count procedure. The same measurements can be achieved using image analysis per Practice E1245.” Some laboratories interpret this note to mean that they can use the ASTM E1245 method at their discretion when the customer has specified ASTM E562. That is not what the note means. It is merely informative. It may be prudent to explicitly state that the ASTM E1245 method may not be substituted.

D6.3.4 Some end-user specifications dictate specific magnifications, grid counts, and number of fields to be examined in each region of the weldment. This practice may be problematic if it is applied to a wide range of product forms and weldment sizes.

D6.3.5 According to ASTM E562 Table 2, when examining a structure with greater than 20% of the phase of interest, a 16-point grid is recommended, based upon “an optimum for efficiency for the time spent counting and for the statistical information obtained per grid placement.” To achieve 10% relative accuracy, the formula in ASTM E562 Table 3 indicates that 25 fields would need to be examined when using a 16-point grid. Magnification selection should be based on the relative size of the phases, according to the guidance in ASTM E562 Paragraph 9.3.

D6.3.6 PI TR 938-C requires one 100 point field be counted in each zone of interest. This provides a first-order approximation of the ferrite percentage at the specific location being examined, but does not provide an estimate of the ferrite percentage in the portion of the weldment of interest, nor does it provide any means for establishing the statistical certainty of the measurement.

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D6.3.8 If filler metal size is specified as an essential variable, extra weld deposit ferrite measurements should be considered if multiple filler metal sizes are qualified using a single WPQT coupon. In this case, consideration should be given to adding a ferrite measurement in the weld metal at roughly the vertical centerline of each extra group of passes performed using a different filler metal size than was used for the locations where the standard measurements are taken.

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D6.3.7 Consideration should be given to locations where ferrite testing is to be performed. API TR 938-C specifies that ferrite should be determined (a) in the parent metal, one measurement on each side of the weld at mid thickness (total of two); (b) in the HAZ on each side of the weld, in the region of the root pass (total of two); and (c) in the weld metal, three measurements near to the vertical centerline of the weld—one in the cap, one in the root, and one at mid thickness (total of three).

D6.3.9 In addition, if the procedure will ever be used to weld on the inside of a component (such as a casting weld repair), consideration should be given to measuring the ferrite in the HAZ adjacent to the cap layer, because it will be exposed to the process. D6.3.10 API TR 938-C includes a statement indicating that ferrite testing is a complicated test, and should only be performed by an experienced laboratory. This is prudent advice. Mathematical errors, improper selection of magnification, and bias (selecting areas for point counts based on how they look rather than randomly) are common errors made by laboratories not very experienced in performing this testing. Consideration should be given to using a laboratory that is not only experienced with this type of testing, but which is also accredited specifically for ASTM 47 E562 testing in accordance with ISO/IEC 17025.

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MR0103-2012 D6.4 Charpy Impact Testing Charpy impact testing is commonly specified for the base metal as well as for the weld deposit and HAZ during weld procedure qualification. This testing usually is not imposed to verify whether the metal and the welding procedure will provide adequate toughness at the test temperature, but rather as an indirect assessment of the metallurgical structure. Typically, the tests are required to be performed at a temperature somewhere within the range of –40 to –51 °C (–40 to –60 °F), with acceptance criteria somewhere within the range of approximately 35 to 50 J (26 to 37 ft-lbf). These results are achievable 48 with proper welding controls. ASTM A923 covers Charpy testing requirements in Method B, but most users either specify their own requirements or supplement the ASTM A923 requirements with their own. D6.5 Corrosion Testing

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Some end users specify ASTM G48 Method A (10% ferric chloride) testing on duplex stainless steels, and often incorporate it into the WPQT requirements. When imposed for weld procedure qualification, the specimen taken from the WPQT coupon is required to include weld deposit, HAZ, and base metal. The specified exposure time is typically 24 h, and the specified test temperature is typically 25 °C (77 °F) for the 22Cr grades and 40 °C (104 °F) for the 25Cr grades. Typically, there are two 2 acceptance criteria: (1) no pitting shall be visible at 20X, and (2) mass loss of no more than 4 g/m . This test is imposed to verify that the weld deposit and HAZ do not contain excessive amounts of carbide or intermetallic phases. ASTM A923 Method C covers ferric chloride corrosion testing requirements, but most users either specify their own requirements based on ASTM G48 Method A or supplement the ASTM A923 requirements with their own. D6.6 Metallographic Examination

Some end users specify a metallographic examination to examine for carbides and other second phases, and often incorporate it into WPQT requirements. These requirements often restrict carbides, sigma phase, and other intermetallic phases to 1% or less. Many laboratories refuse to state compliance with these requirements unless absolutely no second phase is observed, because measurement of constituent percentages this low is very difficult. Some end users feel that the ASTM G48 Method A corrosion testing is a better way to ensure that the microstructure is adequate. D7. Production Testing of Welds

D7.1 Ferrite Testing of Production Welds

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Some end users specify ferrite testing of production welds with a magnetic induction instrument to verify that the base metal and weld deposits exhibit ferrite levels within the required ranges. The ability to determine the ferrite level in the HAZ using this method is questionable, because of the narrow width of the HAZ.

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MR0103-2012

ISBN 1-57590-168-4 NACE International

NOVEMBER 2004

HPIMPACT

SPECIALREPORT

TECHNOLOGY

INTRODUCTION TO NACE STANDARD MR0103

www.HydrocarbonProcessing.com

Reprinted from:

November 2004 issue, pgs 73–77

MATERIALS/RELIABILITY

Used with permission. www.HydrocarbonProcessing.com

Introduction to NACE standard MR0103 Use these materials to reduce sulfide stress cracking in corrosive refinery environments D. R. BUSH, Emerson Process Management / Fisher Controls Intl. LLC, Marshalltown, Iowa, J. C. BROWN, Motiva Enterprises, Convent, Louisiana, and K. R. LEWIS, Shell Global Solutions Intl., BV, Amsterdam, The Netherlands.

any process streams in petroleum refineries contain enough H2S to cause sulfide stress cracking (SSC) in susceptible materials. Until recently, however, no industry standard was available that covered material requirements for sour refinery service. In April 2003, NACE International released MR0103, “Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments.” 1 Several motivating factors led to the development: • Although refineries sometimes specify materials compliant with NACE MR0175,2 application practices varied widely among engineering contractors and users. • Refinery “sour” environments are quite different from the sour environment definitions provided in MR0175. • MR0175 was being revised to address chloride stress corrosion cracking, resulting in unnecessary environmental restrictions on some materials commonly used in refinery applications. The MR0103 document uses borrowed concepts and requirements from various versions of MR0175 with modifications and additions as needed to create a new standard that meets industry needs. For example, MR0103 utilizes the alloy grouping philosophy that is used in what is now NACE MR0175/ISO 15156, but did not implement environmental limits such as H2S partial pressures, temperature limits, pH restrictions, etc. Materials and material condition requirements are based on a mix of MR0175 requirements and refinery-specific experience. There are several major differences between MR0103 and MR0175/ISO 15156: • The refinery standard guidelines for determining whether an environment is “sour” are quite different from the sour environment definitions provided in previous and current versions of MR0175. • The refinery standard does not include environmental restrictions on materials. • Materials and/or material conditions are included in MR0103 that are not listed in MR0175/ISO 15156. • Materials and/or material conditions are included in previous and/or current versions of MR0175/ISO 15156 that are not listed in MR0103. • Because welding is prevalent in refinery piping and equipment, MR0103 places extra emphasis on welding controls in several material groups, most notably the carbon steels.

Applicability of MR0103. Both MR0175 and MR0103

include sections that describe applicability of each of the standards. Both describe material factors and environmental factors, and provide guidelines to the user on how the standard should be applied. Note that both standards require the user to specify whether the environmental conditions are such that the material requirements of the standard should be applied. One of the key differences between the MR0175 and MR0103 standards lies in the guidelines addressing the environmental conditions under which SSC is likely to occur. MR0103 covers a broader range of sour environment conditions experienced in downstream process units. These guidelines are based on: • User’s plant experience and practices • Existing NACE and industry recommended practices and reports (i.e., NACE RP0296,3 8X194,4 8X294,5 API Publication 5816) • A fundamental understanding of atomic hydrogen generation in the sour service corrosion reaction and the subsequent rate of hydrogen flux into the process-contacted steel, i.e., combined effects of pH, H2S and HCN. A significant difference between upstream and downstream sour environments is that, in many refinery sour water environments, dissolved ammonia is present. This increases the pH, thereby increasing the solubility of H2S, which in turn increases the bisulfide ion concentration and corrosivity. Ammonium bisulfide corrosion in these high-pH environments generates a relatively high rate of hydrogen flux. Furthermore, the presence of cyanides at an elevated pH further aggravates the degree of atomic charging and hydrogen flux into the steel by poisoning the surface reaction that results in a stable and protective iron sulfide scale from forming. The outcome of the consensus approach has resulted in the following guidelines on what constitutes a sour service in downstream units. The fluid must contain a free water phase and: • 50 ppmw dissolved H2S in the free water (in recognition that significant levels of dissolved H2S can result in SSC even in low-pressure systems), or • A free water pH 4 and some dissolved H2S present (in recognition that in low-pH environments, significant charging of materials with atomic hydrogen can take place irrespective of

HYDROCARBON PROCESSING NOVEMBER 2004

MATERIALS/RELIABILITY H2S level), or • A free-water pH 7.6 and 20 ppmw hydrogen cyanide ion (HCN) and some H2S dissolved in the free water (in recognition that at high pH, the HCN ion is stable and results in significant charging of ferritic materials by poisoning the formation of a protective iron sulfide scale), or • 0.0003 MPa abs (0.05 psia) partial pressure H2S in a process with a gas phase (based on the historical MR0175 definition of sour service, without the 0.4 MPa abs [65 psia] minimum pressure requirement). Another key difference between MR0175 and MR0103 is that MR0103 allows the user to supplement the environmental guidelines in the standard with actual plant experience and riskbased analysis to determine whether the material requirements of the standard need to be applied. When making this determination, the user is expected to consider all plant operating scenarios, including operational upsets, startup/shutdown conditions, etc. Materials of construction.

Carbon steels. For the most part, refineries use carbon steels classified as P-No. 1 Group 1 or 2 in Section IX of the ASME Boiler and Pressure Vessel Code for piping and vessels.7 MR0103 imposes no base metal hardness requirements on these materials because these grades have maximum tensile strength requirements that effectively limit their bulk hardness. Other carbon steels must meet a 22 HRC maximum requirement. MR0103 shares the following requirements with MR0175: • Carbon steels must be in one of the following heat treatment conditions: (a) Hot-rolled (b) Annealed (c) Normalized (d) Normalized and tempered (e) Normalized, austenitized, quenched and tempered (f ) Austenitized, quenched and tempered. • Carbon steel materials that are cold worked to produce outer fiber deformation greater than 5% must be stress relieved to ensure that the material is below 22 HRC. Welding carbon steels. Welding introduces the potential for creating hard regions in carbon steels. As such, controls must be imposed to ensure that weldments will be soft enough to resist SSC in service. MR0103 requires that welds in P-No. 1 carbon steel materials be performed per the methods outlined in NACE Standard RP0472.8 RP0472 requires that the weld deposit meet a hardness limit of 200 HBW maximum. It requires control of heat-affected zone (HAZ) hardness by one of the following methods: • Post-weld heat treatment • Base metal chemistry controls, usually via a specified maximum carbon equivalent and limits on elements such as niobium, vanadium and boron. Carbon equivalent is defined as: %Mn ( %Ni + %Cu ) ( %Cr + %Mo + %V ) + + 6 15 5 • Custom welding procedure utilizing a combination of welding process controls, base metal chemistry controls (usually less restrictive than method 2 above) and a hardness traverse conducted on the procedure qualification specimen demonstrating that the hardness does not exceed 248 HV in the HAZ. Alloy steels. MR0103 defines alloy steels as those with a chromium content of less than 10%. Total alloying element conCE = %C +

TABLE 1. Low-alloy steel hardness requirements P-Number

Maximum hardness (HBW)

225

235

5B (except 9Cr-1Mo-V grades)

235

5B 9Cr-1Mo-V grades (F91, P91, T91, WP91, Grade 91, C12A)

248

235

10A

225

10B

225

10C

225

P-No. 10F

225

P-No. 11

225

tent can exceed 10%. In practical terms, alloy steels in MR0103 are those steels that contain alloying elements greater than the amounts allowed in carbon steels, but which do not contain enough chromium to be considered stainless steels. Alloy steels with assigned P-Numbers in Section IX of the ASME Boiler and Pressure Vessel Code are required to meet the hardness requirements shown in Table 1. Alloy steels without P-Number assignments must meet a 22 HRC maximum hardness requirement, the same as in the various MR0175 revisions. Welding alloy steels. MR0103 includes very specific information about welding alloy steels. It allows welding P-Number 3 and 4 materials without PWHT in cases where the practice is allowed per ANSI/NB-23.9 In other cases, PWHT is required. In all cases, with or without PWHT, a hardness traverse is required on the PQR specimen to demonstrate that the procedure will produce weldments with hardness values below 248 HV. Martensitic stainless steels. Only specific alloys are listed as acceptable, with specific heat treatment and maximum hardness requirements. The martensitic stainless steel alloys most commonly used in sour applications are S41000, its cast equivalent, CA15 and CA6NM. These alloys are required to be double-tempered and meet maximum hardness requirements of 22 HRC, 22 HRC and 23 HRC, respectively. Welding martensitic stainless steels. For S41000, CA15, and CA6NM, the base material is required to be in the doubletempered condition prior to welding. Weldments in S41000 or CA15 must be PWHT at 1,150°F (620°C) minimum to produce a maximum weldment hardness of 22 HRC. Weldments in CA6NM must be double-tempered per the same requirements as the base metal to produce a maximum weldment hardness of 23 HRC. Precipitation-hardenable martensitic stainless steels. MR0103 includes wrought S17400, S15500, and cast CB7Cu-1 and CB7Cu2 in the general section. These materials are all acceptable in either the double-H1150 or H1150M conditions. The maximum hardness requirements are the same as those specified in the MR0175 documents—33 HRC maximum for the wrought grades, and 310

NOVEMBER 2004 HYDROCARBON PROCESSING

TABLE 2. Composition requirements for austenitic stainless steels

HBW (30 HRC) for the castings. S17400 or S15500 pressureretaining bolting is required to be in the H1150M condition with Element Weight percent a maximum hardness limit of 29 C 0.10 max. HRC. S45000 is allowed with a Cr 16.0 min. single-step precipitation-hardening treatment and a maximum Ni 8.0 min. hardness limit of 31 HRC. Mn 2.0 max. Austenitic stainless steels. Si 2.0 max. The acceptable austenitic stainP 0.045 max. less steel alloys are defined by a S 0.04 max. general composition requirement as shown in Table 2. General composition requirements allow use of many grades of stainless steel that are covered under non-US standards and, as such, were technically unacceptable under MR0175-2002 and previous versions. Austenitic stainless steel materials are required to be in the solution-annealed or solution-annealed and thermally stabilized condition, must be free from cold work intended to enhance mechanical properties and must meet a maximum hardness requirement of 22 HRC. Free-machining alloys containing lead or selenium are not acceptable. Specific austenitic stainless steel grades. MR0103 contains only one specific grade of austenitic stainless steel that doesn’t fit into the standard austenitic stainless steel definition—S20910. This material is allowed in the solution-annealed, hot-rolled or coldworked condition at 35 HRC maximum hardness. All of these conditions are listed in the general section, indicating that all are acceptable for general use. Highly alloyed austenitic (superaustenitic) stainless steels. The highly alloyed austenitic stainless steels (commonly called superaustenitic stainless steels) are defined in MR0103 and MR01752003 as follows: %Ni + (2 × %Mo) >30 and Mo >2% or Pitting resistance equivalent number (PREN ) >40% where PREN is determined as: PREN = %Cr + 3.3 × (%Mo + 0.5 × %W) + 16 × %N These materials are acceptable per MR0103 in the solutionannealed or solution-annealed and cold-worked conditions with a hardness requirement of 35 HRC maximum. Duplex stainless steels. MR0103 allows wrought and cast duplex stainless steels in the solution-annealed and liquidquenched condition to 28 HRC maximum. The material must have a ferrite content of 35– 65%, and heat treatments to increase strength or hardness are not allowed. Welding duplex stainless steel. To ensure that production welds in duplex stainless steels possess the correct microstructure and hardness, MR0103 requires that the PQR and resulting WPS include the following: • The PQR must include a Vickers hardness traverse demonstrating an average value of 310 HV maximum with no individual reading exceeding 320 HV. • The PQR must include examination of the weld deposit and

HAZ conducted in accordance with ASTM E562, demonstrating a ferrite content of 35 to 65 vol%. • The PQR must indicate the heat input used during creating the PQR specimen. The WPS must restrict the heat input to the same value ±10%. • The PQR must list the PQR specimen thickness, and the WPS must restrict welding in production to components with wall thicknesses that do not deviate by more than 20% from that of the PQR specimen thickness. Nickel alloys. Most of the acceptable solid-solution nickel alloys are covered by two compositional definitions: 9.0% Cr minimum, 29.5% Ni + Co minimum, and 2.5% Mo minimum or 14.5% Cr minimum, 52% Ni + Co minimum, and 12% Mo minimum. MR0103 also includes N06600 and N08800 with a maximum hardness requirement of 35 HRC. The wrought nickel-copper alloys N04400 and N04405, and ASTM A494 cast grades M351, M35-2 and M30C are included with a maximum hardness requirement of 35 HRC. MR0103 allows use of a number of cold-worked nickelchromium-molybdenum alloys for general use. These alloys are listed specifically by UNS number as: N06002 (35 HRC max.), N06022 (40 HRC max.), N06625 (35 HRC max.), N06686 (40 HRC max.), N06985 (39 HRC max), N08825 (35 HRC max.) and N10276 (35 HRC max.). Precipitation-hardenable nickel alloys. MR0103 includes all of the precipitation-hardenable nickel alloys that are listed in MR0175-2003 with the same material condition and maximum hardness requirements. In addition, MR0103 added N05500 and N07750, both of which were acceptable according to MR01752002 and previous revisions, but were intentionally omitted from MR0175-2003. The conditions and hardness limits for N05500 and N07750 are the same as those listed in MR0175-2002. Other Alloys. Requirements for cobalt-nickel-chromiummolybdenum alloys, cobalt-nickel-chromium-tungsten alloys and titanium alloys are identical to those in MR0175-2002 and MR0175-2003 with one exception. Laboratory test data for solution-annealed R31233 material indicate it has SSC resistance at hardness levels up to and including 33 HRC, so its hardness limit in MR0103 was set at 33 HRC maximum. The hardness limit for R31233 in all versions of MR0175 is 22 HRC maximum. MR0103 does not address use of copper alloys or tantalum. Aluminum is only addressed for use in pistons and gaskets in Section 9 on Compressors and Pumps. Fabrication. The fabrication section covers overlays; welding; cladding on carbon, alloy and martensitic stainless steels; identification stamping; threading and cold-deformation processes. With the exception of the cladding coverage on carbon, alloy and martensitic stainless steels, which is unique to the MR0103 document, these sections are essentially identical to, or very similar to, the corresponding sections in MR0175-2003. In MR0103, some of the information regarding welding and weld overlays in specific alloy groups has been incorporated into general sections covering those alloy groups. The cladding section was included because many refineries use cladding to prevent corrosion and SSC in less-resistant base materials. To meet MR0103, cladding materials must be

HYDROCARBON PROCESSING NOVEMBER 2004

MATERIALS/RELIABILITY TABLE 3. Typical refinery equipment susceptible to sulfide stress cracking (Note: this list is not all-inclusive) Crude units—atmospheric and vacuum

Atmospheric tower overhead system

Coolers, accumulators

Vacuum tower overhead system

Coolers, accumulators

Light ends recovery section

Debutanizers, waste gas scrubbers, sour water collection system

Main fractionator overhead system

Overhead line, coolers/condensers, accumulators, coalescers, absorbers

Wet gas system

Compressor suction drum, accumulators, coolers

Light ends recovery section

Deethanizers, debutanizers, accumulators

Feed system

Feed surge drums

Reactor effluent section

High/low pressure separators, trim coolers

Fractionation section

Stripper towers, reflux drums

Gas treating section

Amine absorbers, off-gas absorber, flash tower

Recycle gas systems

Knock-out pots, condensers

Coker units

Coker fractionator overhead system, Coker light ends recovery section

Similar to FCCU

Other

Sour water recovery units

Sour water stripper column overhead system

Amine regenerator systems

Amine regenerator tower, accumulator drum, quench tower

Gas recovery plants

Similar to light ends recovery above

Sulfur recovery units

Acid gas knock-out drums, condensers, blow-down drums

Catalytic cracking units

Hydroprocessing units

selected from sections 2 or 3 of MR0103, and must be applied by hot rolling, explosion bonding or weld overlaying. Some of the factors that influence clad component SSC resistance are listed for consideration by the end user. Because evaluating all of the relevant factors is outside the scope of MR0103, the end user is responsible for specifying whether the base metal must meet the requirements of MR0103. Bolting. Bolting requirements in MR0103 are only slightly modified from those listed in MR0175-2002 and MR0175-2003. Two differences are the reference to special requirements for S17400 and S15500 when used for pressure bolting, and a warning statement indicating that zinc and cadmium coatings should not be used in sour environments because they enhance hydrogen generation on the surface, which can contribute to hydrogen cracking. The definitions for “exposed” and “nonexposed” bolting are the same as those in MR0175. Plating, coatings, and diffusion processes. The requirements listed in this section are identical to those in the MR0175 documents. In essence, these types of coatings are acceptable provided they are not used in an attempt to protect an otherwise unacceptable base metal. Special components. This section covers special requirements for certain types of components that often cannot be made from materials listed in the general materials sections of the document, such as bearings, springs, instrumentation and control devices, seal rings and gaskets, snap rings and special process parts. The requirements listed in this section are identical to those in the corresponding sections of MR0175-2002 and MR0175-2003. Valves. The valves section simply states that new and reconditioned valves, including internal components, must be manufactured from materials meeting the requirements of section 2 or 3. Compressors and pumps. In general, compressors and pumps must be manufactured from materials meeting the requirements of section 2 or 3. However, this section provides a few alterna-

tive materials for cylinders, liners, pistons, valves, gaskets and impellers. Several end users and engineering contractors are already specifying equipment per MR0103. Eventually, a broad range of users and authors of equipment standards is expected to adopt the new MR0103 standard for downstream applications, in many cases replacing the current application of MR0175. The environmental guidelines and material requirements of MR0103, together with NACE RP0472 for weld hardness control of P-No. 1 carbon steels, should be broadly applied to piping, valves, process contacted bolting, pumps and compressors used in the sour service areas of the refinery process units, as indicated in Table 3, to prevent SSC. HP LITERATURE CITED NACE Standard MR0103-2003, “Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments,” Houston, Texas: NACE. 2 NACE Standard MR0175-2003, “Metals for Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments,” Houston, Texas: NACE. 3 NACE Standard RP0296 (latest revision), “Guidelines for Detection, Repair, and Mitigation of Cracking of Existing Petroleum Refinery Pressure Vessels in Wet H2S Environments,” Houston, Texas: NACE. 4 NACE Publication 8X194 (latest revision), “Materials and Fabrication Practices for New Pressure Vessels Used in Wet H2S Refinery Service,” Houston, Texas: NACE. 5 NACE Publication 8X294 (latest revision), “Review of Published Literature on Wet H2S Cracking of Steels Through 1989,” Houston, Texas: NACE. 6 API Publication 581 (latest revision), “Base Resource Document—Risk-based Inspection,” Washington, DC: American Petroleum Institute. 7 ASME Boiler and Pressure Vessel Code, Section IX, Division I (latest revision), “Welding and Brazing Qualifications,” New York, New York: ASME. 8 NACE Standard RP0472 (latest revision), “Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments,” Houston, Texas: NACE. 9 ANSI/NB-23, “National Board Inspection Code,” Columbus, Ohio: The National Board of Boiler and Pressure Vessel Inspectors. 1

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MATERIALS/RELIABILITY

Don Bush is a senior engineering specialist for Emerson Process Management in Marshalltown, Iowa. He has over 25 years of experience dealing with all aspects of materials engineering relating to Fisher control valve, actuator and instrument products, including evaluating new materials, writing material specifications, supporting manufacturing operations, selecting materials for severe service and performing failure analysis. Mr. Bush received a BS degree in metallurgical engineering from Iowa State University. He is a registered professional engineer in Iowa, a member of ASM International and NACE International, and is the chairman of NACE Task Group 231, which developed and now maintains the MR0103 standard. Mr. Bush has published numerous materials-related articles in a variety of technical and trade journals.

Keith Lewis is the Shell Global Solutions International B.V. business team manager for downstream materials and inspection engineering, based in Amsterdam, The Netherlands. He has more than 25 years of experience providing engineering and consulting services to refining and petrochemical projects and operating plants throughout the world. Mr. Lewis is the past chairman of the NACE International technology group on Refining and Gas Processing Corrosion, and is currently the NACE Technology Coordinator overseeing Standards and Reports applicable to the oil and gas industries. He has a BSc (Hons.) degree in metallurgy from Leeds University, UK, and is a Chartered Engineer. Mr. Lewis has published many articles on materials, corrosion and integrity issues affecting the oil, gas and petrochemicals business.

John C. (Jeff) Brown, of Motiva Enterprises, is the corrosion and materials coordinator for its Convent refinery. He has worked in various positions within the refining industry since 1977. Mr. Brown received his BA degree in business administration from Catawba College and a BS degree in engineering from Widener University. He is a member of ASM, has coauthored several papers available through NACE, and is very active within the NACE organization. He is currently the chairman of NACE Task Group 300 and is the vice chairman of Task Group 231.

D351198X012

PIC MSCQ

HYDROCARBON PROCESSING NOVEMBER 2004

AN OVERVIEW OF NACE INTERNATIONAL STANDARD MR0103 AND COMPARISON WITH MR0175 Don Bush Emerson Process Management / Fisher Controls Intl. LLC PO Box 190 Marshalltown, Iowa 50158 don.bush@emersonprocess.com Jeff Brown Motiva Enterprises PO Box 37 Rt 44 & 70 Convent, LA 70723 Keith Lewis Shell Global Solutions Intl., BV Badhuisweg 3 Amsterdam, 1031-CM Netherlands ABSTRACT NACE MR0103 "Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments"1 was developed by Task Group 231 to provide a standard set of requirements for materials used in sour petroleum refinery equipment. In the past, NACE MR01752, "Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment", was frequently referenced for this equipment, even though refinery applications were outside the scope of MR0175. The process used to develop MR0103 is described, followed by a review of the requirements in the standard accompanied by highlights of the differences between MR0103 and the previous and current versions of MR0175. INTRODUCTION AND DOCUMENT HISTORY In 1975, NACE issued standard MR0175, "Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment", to cover requirements for materials resistant to sulfide stress cracking (SSC) in sour oilfield environments. Although the scope of MR0175 includes only oilfield equipment and associated facilities (including gas production and treatment), the lack of similar standards for other industries has compelled many users in those industries to reference MR0175 for materials destined for “sour” applications. Although the process conditions that constitute the non-oilfield “sour” environments are often quite different from those defined in MR0175, the material and material condition requirements have proven to be fundamentally on target.

In the late 1990’s, the NACE T-1F-1 task group, now called Task Group (TG) 081, began working on a complete rewrite of MR0175 that included a number of fundamental changes. One of the most significant proposed changes was the expansion of the scope of the document to include chloride stress corrosion cracking (SCC), based upon the fact that most oil and gas production streams contain chlorides in sufficient levels to cause SCC in susceptible alloys. As such, the proposed rewrite included maximum temperature limits for all materials that are susceptible to chloride SCC. For example, the rewrite proposed that the temperature limit for S31600 (type 316 stainless steel) be set at 60°C (140°F) maximum. The proposed changes would mean that MR0175 would be less suitable for use in many applications, including those in petroleum refineries, where chloride ion concentrations tend to be low enough that chloride SCC isn’t a common concern. Initial discussion regarding the proposed changes to MR0175 and the potential development of a refinery-specific standard covering materials for sour environments occurred during the 1997 Fall Committee Week T-8 Information Exchange session. Further discussions, including review of drafts of proposed document sections, were held at subsequent T-8 Information Exchange sessions and at several Task Group (TG)T-8-25 ("Environmental Cracking") meetings. At Corrosion/2000, it was decided that a T-8-25 Work Group (T-8-25a) would be formed to develop a sulfide stress cracking document. This Work Group was eventually formed in June 2000 as TG (Task Group) 231 under the current NACE technical committee structure. TG 231 is administered by STG (Specific Technology Group) 34 "Petroleum Refining and Gas Processing" and sponsored by STG 60 "Corrosion Mechanisms". The task group's writing approach was to borrow pertinent concepts and requirements from the current and proposed versions of MR0175, and modify them as needed to create a new standard that would meet the needs of the oil refining industry. For example, the resulting document utilized the alloy grouping philosophy that is used in what is now MR0175-20033, but did not implement environmental limits such as H2S partial pressures, temperature limits, pH restrictions, etc. Materials and material condition requirements are based upon a mix of MR0175-2002 and MR0175-2003 requirements and refinery-specific experience. Because of this approach, there are paragraphs in MR0103 that are identical to corresponding paragraphs in one or both versions of MR0175, whereas in other instances, the requirements in MR0103 have been modified to better suit the needs of the oil refining industry. The final result is a document that differs from previous and current versions of MR0175 in the following ways: •

The refinery standard guidelines for determining whether an environment is "sour" are quite different from the sour environment definitions provided in previous and current versions of MR0175.

•

The refinery standard does not include environmental restrictions on materials.

•

Materials and/or material conditions are included in the refinery standard that are not listed in previous and/or current versions of MR0175.

•

Materials and/or material conditions are included in previous and/or current versions of MR0175 that are not listed in the refinery standard.

•

Because welding is prevalent in refinery piping and equipment, extra emphasis is placed upon welding controls in several material groups, most notably the carbon steels.

The document was developed using the approved NACE work process. Various sections were drafted, reviewed at Corrosion and Fall Committee Week meetings, and then finalized based upon the feedback that was received. The "final" draft was sent out for formal letter ballot in mid-July 2002. This initial ballot resulted in 4 negative votes and 17 affirmative votes with comments. The document was modified to address the negative votes and other comments, and was sent out for reballot in January 2003. The reballot passed with a 97% affirmative vote after negative vote resolution. The MR0103 standard "Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments" was published in mid-April 2003. Following is an overview of the document, including discussion of pertinent differences among MR0175-2002, MR0175-2003, and MR0103. NACE CORROSION/2004 Paper 04649

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APPLICABILITY OF MR0175 AND MR0103 Both MR0175 and MR0103 include sections that describe the applicability of each of the Standards. Within each of these sections there are sub-sections that describe the material and environmental factors that affect susceptibility of materials to SSC and also provide guidelines to the user on how the Standard should be applied. It is extremely important to note that in both MR0175 and MR0103 the user is responsible for determining and judging whether the environmental conditions are such that the material requirements of the Standard should be applied. One of the key differences between the MR0175 and MR0103 Standards lies in the guidelines addressing the environmental conditions under which SSC is likely to occur. This difference between the upstream (oil and gas production) and downstream (refining and gas processing) environments was one of the principal reasons why NACE STG 34/TG 231 decided to write the MR0103 Standard. MR0103 is more focused on a broader range of sour environments conditions experienced in MR-0175, downstream process units.

definition.

The MR0175 definition of sour service environments in upstream processes is very well known and understood, having remained essentially unchanged for almost 30 years. In the 2003 version of MR1075 the environmental conditions likely to cause SSC are described in Paragraphs 1.4.1 and .4.2 with sample calculations in Appendix A. Simply summarized, these conditions consist of a partial pressure of H2S in the wet gas phase of a gas, gas condensate or crude oil equal to or exceeding 0.0003MPa abs (0.05 psia). For gas systems there is a low-pressure cut-off (i.e., total system pressure below which SSC is not expected to occur) of 0.45 MPa abs (65 psia) and for multiphase phase systems the low-pressure cut-off is 1.83 MPa abs (265 psia), (with other conditions applying). The MR0175 definition of sour service has also been widely and successfully applied by users in many downstream facilities either directly in company specifications and practices or indirectly via the application of API equipment specifications such as API RP 6104, 6175 and 6186. However, for downstream applications many users, engineering contractors and suppliers have over the years developed their own practices on how and when MR0175 material requirements should be applied. These practices have ranged between: •

No application at all, irrespective of H2S level since some downstream users have considered MR0175 strictly applicable to upstream applications,

•

Application of MR0175 material requirements to any process containing H2S, including trace levels in services with no free water present.

In the new MR0103 Standard an attempt has been made to develop consensus guidelines on what constitutes sour service in downstream units based on: •

User’s plant experience and practices;

•

Existing NACE and industry recommended practices and reports (i.e. NACE RP02967, 8X1948, 8X2949, API Publication 58110);

•

A fundamental understanding of atomic hydrogen generation in the sour service corrosion reaction and the subsequent rate of hydrogen flux into the process-contacted steel i.e., combined effects of pH, H2S and HCN.

A significant difference between upstream and downstream sour environments is that in many refinery sour water environments dissolved ammonia is present which increases the pH thereby

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increasing the solubility of H2S, which in turn increases the bisulfide ion concentration and corrosivity. Ammonium bisulfide corrosion in these high pH environments generates a relatively high rate of hydrogen flux. Furthermore, the presence of cyanides at an elevated pH further aggravates the degree of atomic charging and hydrogen flux into the steel by poisoning the surface reaction that results in a stable and protective iron sulfide scale from forming. The outcome of the consensus approach, embodied in MR0103, has resulted in the following guidelines (with additional explanation in parenthesis) on what constitutes a sour enough service in downstream units to justify the application of the Standard’s material requirements (Note: the presence of a free water phase is a prerequisite for aqueous corrosion and SSC):

MR-0103,

•

>50 ppmw dissolved H2S in the free water (recognition that significant levels of dissolved definition. H2S can result in SSC even in low pressure systems), or

•

A free water pH < 4 and some dissolved H2S present (recognition that in low pH environments significant charging of materials with atomic hydrogen can take place irrespective of H2S level), or

•

A free water pH > 7.6 and > 20 ppmw hydrogen cyanide ion (HCN) and some H2S dissolved in the free water (recognition that at high pH the HCN ion is stable and results in significant charging of ferritic materials by poisoning the formation of a protective iron sulfide scale), or

•

>0.0003 MPa abs (0.05 psia) partial pressure H2S in a process with a gas phase (based on historical MR0175 definition of sour service, without low-pressure cut-offs).

Another key difference between the MR0175 and MR0103 Standards is the way the user is expected to use the guidelines on environmental conditions. In MR0175 the user is obligated apply the material requirements of the Standard when it is judged that the environmental conditions prescribed in the Standard have been exceeded; however, there is relatively little judgment required since the environmental conditions for SSC are tightly defined with sample calculations provided in Appendix A. In MR0103 the user is also obligated to determine whether the equipment falls within the scope of the standard; however, more judgment of the environmental conditions is permitted, and the user may supplement the environmental guidelines in the Standard with actual plant experience and risk based analysis to make a determination on applicability (API Publication 581 provides a methodology for such an analysis). However, when making this judgment the MR0103 user is expected to consider all plant operating scenarios including operational upsets, start-up/shutdown conditions etc. MATERIALS OF CONSTRUCTION

As applicable for sour service.

Carbon Steels Carbon steels are the workhorse materials in refineries, and as such they have received a great deal of attention in previous NACE activities. For the most part, refineries use carbon steels classified as P-No. 1 Group 1 or 2 in Section IX of the ASME Boiler and Pressure Vessel Code11 (grades such as ASTM A10512 forgings, ASTM A21613 WCC and A35214 LCC castings, ASTM A51615 Grade 70 plate, ASTM A106 Grade B pipe) for piping and vessels. Unlike MR0175-2002 and MR0175-2003, MR0103 imposes no base metal hardness requirements on these materials due to the fact that these grades have maximum tensile strength requirements that effectively limit their bulk hardness. Other carbon steels are required to meet a 22 HRC maximum requirement.

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MR0103 shares the following requirements with MR0175-2002 and MR0175-2003: •

Carbon steels must be in one of the following heat treatment conditions: (a) hot-rolled (b) annealed (c) normalized (d) normalized and tempered (e) normalized, austenitized, quenched, and tempered (f) austenitized, quenched, and tempered

•

Carbon steel materials that are cold worked to produce outer fiber deformation greater than 5%, must be stress relieved to ensure that the material is below 22 HRC.

Welding of Carbon Steels Welding introduces the potential for creation of hard regions in carbon steels. As such, controls must be imposed to ensure that weldments will be soft enough to resist sulfide stress cracking in service. MR0103 requires that welds in P-No. 1 carbon steel materials be performed per the methods outlined in NACE Standard RP0472 “Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments”16. RP0472 is a recommended practice document that was issued by the T-8 Unit Committee on Refinery Corrosion in 1972. Note that this document actually pre-dates MR0175, although the scope and requirements have changed somewhat since its initial release. RP0472 requires that the weld deposit meet a hardness limit of 200 HBW maximum. It allows control of heat-affected zone (HAZ) hardness by several different methods. Those methods include: Post-weld heat treatment (PWHT): PWHT serves two purposes. As a tempering process, it reduces the hardness of the weld deposit and the heat affected zone (HAZ). As a stress relieving process, it reduces residual stresses in the weldment through stress relaxation. Both of these effects tend to reduce the probability of failure due to SSC. Although some of the ASME codes allow the option of using lower temperatures for longer times, this option is not recommended. Using lower temperatures for longer times may provide reduction in residual stresses, the primary concern of the ASME codes, but is less likely to reduce HAZ hardness, which is the primary factor in reducing susceptibility to SSC. Base metal chemistry controls: This technique involves controlling of carbon content and/or carbon equivalent and levels of micro-alloying elements in base metals to such low levels that low hardness is virtually guaranteed in the weld deposit and HAZ regardless of welding process parameters. The carbon equivalent of a particular heat of material is calculated from the heat chemistry using the following equation: CE = %C +

%Mn 6

(%Ni + %Cu) 15

(%Cr + %Mo + %V) 5

NACE Committee Report 8X194 states that a maximum carbon equivalent of 0.43 is commonly specified for base materials when this technique is employed. Deliberate additions of micro-alloying elements (greater than 0.01% each of Cb, V, and Ti, or greater than 0.0005% B) are usually prohibited to ensure that hardenability will remain low.

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HAZ hardness testing during welding procedure qualification: When this method is used, a procedure qualification record (PQR) specimen is created using either actual production material or a coupon of representative material with an actual carbon equivalent corresponding to the maximum carbon equivalent value that is to be applied to production base material. Welding variables (such as filler metal, preheat, current, voltage, travel speed, interpass temperature, etc.) are controlled and documented during the creation of the PQR specimen. The PQR tests include a hardness traverse performed using the 5-kgf or 10-kgf Vickers scale or the Rockwell 15N scale to demonstrate that the weldment hardness does not exceed 248 HV or 70.5 HR15N in the weld metal, HAZ and base metal. The resulting welding procedure specification (WPS) is written to contain restrictions to ensure that the PQR specimen is actually representative of production weldments. Those restrictions include the following: •

The procedure may only be used to weld a base metal of the same specification, grade, and class as that of the PQR specimen. In other words, a procedure qualified on ASTM A516 Grade 70 plate material could not be used to weld ASTM A516 Grade 60 plate material, ASTM A105 forgings, or ASTM A216 Grade WCC castings, even though all are within the same ASME Section IX P-No. 1 category.

•

The maximum CE and micro-alloying element contents of production material must be controlled to values less than or equal to those of the PQR specimen.

•

The heat input used during production welding must not deviate from the heat input used during creation of the PQR specimen by more than 10% lower or 25% higher. For the shielded metal arc welding (SMAW) process, the maximum bead size and the minimum length of weld bead per unit length of electrode used in creation of the PQR specimen can be imposed as an alternate requirement in the WPS.

•

Preheat and interpass temperatures must be at least as high as those utilized in production of the PQR specimen.

•

If preheat was not utilized for the PQR specimen, the maximum base metal thickness of production weldments must not be allowed to exceed the thickness of the PQR specimen.

Other restrictions apply to fillet welds, submerged-arc welding (SAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW) processes, welding procedures involving bead-tempering techniques and other techniques that are sensitive to weld-bead sequence, and materials containing intentional additions of microalloying elements such as Nb (Cb), V, Ti, and B. This method may not be suitable for certain applications such as repair welding of castings. It is generally utilized for establishment of an acceptable welding procedure for a particular heat of material for a large job. An example would be the fabrication of a large vessel from a single heat of plate material which doesn't have chemistry restrictions that are adequate to guarantee low weldment hardness. The wording regarding welding of carbon steels in MR0175-2002 and previous versions has always been somewhat subject to misinterpretation. Paragraph 5.3.1.2 from MR0175-2002 reads as follows: “5.3.1.2 Welding procedure qualifications on carbon steels that use controls other than thermal stress relieving to control the hardness of the weldment shall also include a hardness traverse across the weld, HAZ, and base metal to ensure that the procedure is capable of producing a hardness of 22 HRC maximum in the condition in which it is used.”

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This paragraph has often been misinterpreted to mean that if a welding procedure qualification performed on a P-No. 1 carbon steel included a hardness traverse with results meeting the 22 HRC maximum requirement, that the resulting procedure was acceptable for producing welds meeting MR0175 requirements in all P-No. 1 materials. Unfortunately, this is not the case, since the hardenability of P-No. 1 carbon steels varies quite widely depending upon the actual carbon and manganese contents as well as the levels of residual elements such as chromium, nickel, molybdenum, copper, and vanadium. The phrase “controls other than thermal stress relieving” in paragraph 5.3.1.2 is a vague reference to the need for control of chemistry and/or welding parameters that are above and beyond those required by the parent material specification and/or the ASME Section IX welding requirements. These extra controls ensure that as-welded hardness values will be acceptable. The wording in the 2003 version of MR0175 has been modified to be somewhat more specific: “5.3.1.2 Welding procedures for carbon steels and low-alloy steels may control welding variables to achieve a hardness of 22 HRC maximum in the weldment. The controls generally involve restricted base and filler metal chemical composition and welding parameters. The procedure qualification shall verify that the 22 HRC maximum hardness requirement is achieved in the weld deposit, HAZ, and base metal in the aswelded condition. The resulting welding procedure specification shall document the required controls to assure that the 22 HRC maximum hardness requirement will be achieved in production weldments. 5.3.1.3

Carbon steel and low-alloy steel weldments produced without restrictions on base and filler metal chemical compositions and welding parameters in accordance with Paragraph 5.3.1.2 shall be post-weld heat treated at a minimum temperature of 621°C (1,150°F) to produce a hardness of 22 HRC maximum.”

Although the intent has not changed, the paragraphs in MR0175-2003 now state the intended requirements much less ambiguously than in previous versions of MR0175. Alloy Steels MR0103 defines alloy steels as steels with a chromium content of less than 10%. Total alloying element content can exceed 10%. In practical terms, alloy steels in MR0103 are those steels that contain alloying elements greater than the amounts allowed in carbon steels but which do not contain MR-0175,criteria enough chromium to be considered stainless steels.

for alloy steels. MR0175 has always limited the nickel content in carbon and alloy steel base metals and weld filler materials to 1% maximum. The main intent of the restriction was to limit the use of nickel in highstrength casing and tubular materials and in high-strength wellhead equipment. There has been a great deal of discussion over the years regarding the validity of the "nickel effect" concept - i.e., the theory that a nickel content above 1% reduces the resistance of a steel to SSC. Some tests have indicated that such steels are susceptible to SSC at bulk hardness levels below 22 HRC. Others have suggested that the reduced SSC resistance in these examples is due to the presence of a mixed microstructure containing untempered martensite caused by tempering above the lower critical temperature, which is relatively low in nickel-alloy steels17. Attempts to add alloy steels with more than 1% nickel to the general section by letter ballot have been unsuccessful.

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The refinery industry has no need for the high-strength nickel-containing alloy steels. On the other hand, there is a need in some locations for materials with good impact toughness at low temperatures. Discussions at TG 231 meetings indicate that the 3½% nickel steels such as ASTM A33318 Grade 3, A35019 LF3, and A352 LC3 have been used for this purpose, and have demonstrated reliable performence in sour refinery environments for many years. As such, the nickel restriction was not included in MR0103. Alloy steels with assigned P-Numbers in Section IX of the ASME Boiler and Pressure Vessel Code are required to meet the hardness requirements shown in Table 1:

MR-0103, requirements.

Table 1: Low Alloy Steel Hardness Requirements P-Number 3 4 5A 5B (except 9Cr-1Mo-V grades) 5B 9Cr-1Mo-V grades (F91, P91, T91, WP91, Grade 91, C12A) 5C 6 7 10A 10B 10C P-No. 10F P-No. 11

Maximum Hardness (HBW) 225 225 235 235 248 235 235 235 225 225 225 225 225

Alloy steels without P-Number assignments must meet a 22 HRC maximum hardness requirement, the same as required in the various MR0175 revisions. In MR0175 (2002 and 2003), low alloy steels are defined as a “steels with a total alloying element content of less than about 5%, but more than specified for carbon steel”. Low alloy steels are also restricted to a maximum nickel content of 1%. Note that according to these definitions, the 5 Cr-½ Mo steels are borderline, and the 9 Cr-1 Mo steels are unacceptable, as are the impact-tested nickel steels commonly used for low temperature service (such as LC3 and LF3). Welding of Alloy Steels MR0103 includes very specific information about welding of alloy steels. It allows welding of PNumber 3 and 4 materials without PWHT in cases where the practice is allowed per ANSI/NB-2320. In other cases, PWHT is required. In all cases, with or without PWHT, a hardness traverse is required on the PQR specimen to demonstrate that the procedure will produce weldments with hardness values below 248 HV. MR0175-2002 required low-alloy steels to be PWHT at 1150°F (620°C) minimum to produce a maximum hardness of 22 HRC.

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MR0175-2003 includes the same requirements for low-alloy steel weldments as for carbon steel weldments (requirements for both are covered in the same paragraph). Welding without PWHT is allowed. However, there are only certain circumstances where the construction codes will allow welding of particular alloy steels without PWHT, so the construction code restrictions would also need to be considered prior to utilizing this allowance. Martensitic Stainless Steels The requirements for martensitic stainless steel base metals are essentially the same in the two versions of MR0175 and in MR0103. Only specific alloys are listed as acceptable, with specific heat treatment and maximum hardness requirements. The martensitic stainless steel alloys most commonly used in sour applications are S41000, its cast equivalent, CA15, and CA6NM. These alloys are required to be double-tempered and meet maximum hardness requirements of 22 HRC, 22HRC, and 23 HRC, respectively. Welding of Martensitic Stainless Steels Descriptions of welding requirements for martensitic stainless steels differ somewhat among MR0175-2002, MR0175-2003, and MR0103, although it appears that the intent is the same in all of the documents. In all cases for S41000, CA15, and CA6NM, the base material is required to be in the double-tempered condition prior to welding. Weldments in S41000 or CA15 must be PWHT at 1150Â°F (620Â°C) minimum to produce a maximum weldment hardness of 22 HRC. Weldments in CA6NM must be double-tempered per the same requirements as the base metal to produce a maximum weldment hardness of 23 HRC. Precipitation-Hardenable Martensitic Stainless Steels MR0103 includes wrought S17400, S15500, and cast CB7Cu-1 and CB7Cu-2 in the general section. These materials are all acceptable in either the double-H1150 or H1150M conditions. The maximum hardness requirements are the same as those specified in the MR0175 documents - 33 HRC maximum for the wrought grades, and 310 HBW (30 HRC) for the castings. S17400 or S15500 pressure-retaining bolting is required to be in the H1150M condition with a maximum hardness limit of 29 HRC. S45000 is allowed with a single-step precipitation-hardening treatment and a maximum hardness limit of 31 HRC. MR0175-2002 included wrought S17400 in the general section in both the double-H1150 and H1150M conditions, with a hardness limit of 33 HRC maximum. Wrought S45000 was also listed in this section, with a single-step precipitation-hardening treatment and a maximum hardness limit of 31 HRC. The cast version of S17400, CB7Cu-1, was listed in section 9 in the double-H1150 condition with a maximum hardness limit of 310 HBW (30 HRC) for use only in non-pressure-containing, internal valve, and pressure regulator components. In MR0175-2003, there are no precipitation-hardenable martensitic stainless steels listed in the general section. Wrought S17400, S15500, and S45000, as well as cast CB7Cu-1 and CB7Cu-2 are listed only in section 9 for certain uses in wellheads, christmas trees, valves, chokes, and level controllers. Heat treatment requirements and hardness limits are the same as those in MR0175-2002.

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Austenitic Stainless Steels The material requirements for the austenitic stainless steels in MR0103 are nearly identical to those in MR0175-2003. The acceptable alloys are defined by a general composition requirement as shown in Table 2: Table 2: Composition Requirements for Austenitic Stainless Steels Element C Cr Ni Mn Si P S

Weight Percent 0.10 max. 16.0 min. 8.0 min. 2.0 max. 2.0 max. 0.045 max. 0.04 max.

The use of general composition requirements allows the use of many grades of stainless steel which are covered under non-US standards and as such were technically unacceptable under MR01752002 and previous versions. Austenitic stainless steel materials are required to be in the solutionannealed or solution-annealed and thermally stabilized condition, must be free from cold work intended to enhance mechanical properties, and must meet a maximum hardness requirement of 22 HRC. Freemachining alloys containing lead or selenium are not acceptable. The compositional requirements in MR0103 vary slightly from those in MR0175-2003. MR0103 allows a maximum carbon content of 0.10%, which allows the use of the "H-grade" stainless steels. MR0175-2003 has a maximum carbon content requirement of 0.08% except for S30900 and S31000, which may contain up to 0.10% carbon. In addition, MR0175-2003 is somewhat ambiguous regarding sulfur content. In the compositional definition, sulfur is allowed up to 0.04%, but the statement "Freemachining austenitic stainless steel products (containing alloying elements such as lead, selenium, or sulfur to improve machinability) are not acceptable" gives the impression that no sulfur is allowed. MR0175-2002 and previous versions listed specific grades of austenitic stainless steels, all of which were grades covered by UNS21 numbers. This essentially precluded the use of materials covered by non-US standards even though they were equivalent or very similar to the materials listed in the standard. Specific Austenitic Stainless Steel Grades MR0103 contains only one specific grade of austenitic stainless steel that doesn't fit into the standard austenitic stainless steel definition - S20910. This material is allowed in the solutionannealed, hot-rolled, or cold-worked condition at 35 HRC maximum hardness. All of these conditions are listed in the general section, indicating that all of these conditions are acceptable for general use. MR0175-2002 and MR0175-2003 list solution-annealed and hot-rolled material in the general section, but only allow the cold-worked material to be used for valve shafts, stems, and pins.

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Highly Alloyed Austenitic (Superaustenitic) Stainless Steels The highly alloyed austenitic stainless steels (commonly called superaustenitic stainless steels) are defined in MR0103 and MR0175-2003 as follows: %Ni + (2 x %Mo) >30 and Mo >2% or Pitting Resistance Equivalent Number (PREN) >40% where PREN is determined as follows:

PREN = %Cr + 3.3 × (%Mo + 0.5 × %W) + 16 × %N These materials are acceptable per MR0103 in the solution-annealed or solution-annealed and cold-worked conditions with a hardness requirement of 35 HRC maximum. MR0175-2003 lists these materials in the general section in the solution-annealed condition only. Cold-worked material is allowed only for downhole tubular components, where the hardness requirement is 35 HRC maximum. MR0175-2002 and previous revisions only listed specific alloys in this category. The maximum hardness limits on the various alloys and forms ranged from 94 HRB to 38 HRC. Duplex Stainless Steels

MR0103 allows wrought and cast duplex stainless steels in the solution-annealed and liquidquenched condition to 28 HRC maximum. The material must have a ferrite content of 35-65%, and heat treatments to increase strength or hardness are not allowed. The requirements listed in MR0175-2003 are similar, except there are no hardness requirements listed for solution-annealed and liquid-quenched materials. A hardness requirement of 25 HRC maximum is imposed on hot isostatic pressure-produced S31803. Solution-annealed, quenched, and cold-worked duplex stainless steels are allowed for down-hole tubular components to 36 HRC maximum. MR0175-2002 listed only specific grades of duplex stainless steels, some of which were only acceptable in the solution annealed condition, and others which were allowed in the cold-worked condition. Maximum hardness requirements ranged from 17 HRC to 36 HRC. Welding of Duplex Stainless Steel

In order to ensure that production welds in duplex stainless steels possess the correct microstructure and hardness, MR0103 requires that the PQR and resulting WPS include the following: •

The PQR must include a hardness traverse conducted using 10 kgf Vickers encompassing the base metal, HAZ, and filler metal at the top and bottom of the weldment. The hardness may not exceed an average value of 310 HV 10, and no individual reading may exceed 320 HV 10.

•

The PQR must include an analysis of the ferrite content of the weld deposit and HAZ conducted in accordance with ASTM E562. The measured ferrite content must be 35 to 65 vol%.

•

The PQR must indicate the heat input used during creation of the PQR specimen. The WPS must restrict the heat input to the same value ±10%.

•

The PQR must list the thickness of the PQR specimen, and the WPS must restrict welding in production to components with wall thicknesses which do not deviate by more than 20% from that of the PQR specimen thickness.

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The only requirement provided for welding of duplex stainless steels in MR0175-2003 is that the PQR must assure that all regions of the weldment contain 30-70% ferrite. MR0175-2002 and previous versions did not address welding of duplex stainless steels. Nickel Alloys

MR0103 covers the wrought solid-solution nickel alloys in much the same manner as MR01752003. Most of the acceptable alloys are covered by two compositional definitions as follows: 9.0% Cr minimum, 29.5% Ni + Co minimum, and 2.5% Mo minimum.

14.5% Cr minimum, 52% Ni + Co minimum, and 12% Mo minimum.

These alloys are acceptable in the solution-annealed condition without any maximum hardness requirement. This set of compositional ranges covers many of the materials which were included in MR0175-2002 and previous revisions. However, the molybdenum requirements precluded N06600 and N08800, which are sometimes utilized in refineries and have demonstrated acceptable sulfide stress cracking resistance. As such, MR0103 also includes N06600 and N08800 with a maximum hardness requirement of 35 HRC, which matches the requirements for these materials in MR0175-2002. In addition, the wrought nickel-copper alloys N04400 and N04405, and ASTM A49422 cast grades M35-1, M35-2, and M30C are included with a maximum hardness requirement of 35 HRC. MR0103 allows the use of a number of cold-worked nickel-chromium-molybdenum alloys for general use. These alloys are listed specifically by UNS number as follows: N06002 (35 HRC max.), N06022 (40 HRC max.), N06625 (35 HRC max.), N06686 (40 HRC max.), N06985 (39 HRC max), N08825 (35 HRC max.), and N10276 (35 HRC max.). MR0175-2002 also included cold-worked nickel-chromium-molybdenum alloys in the general use section. MR0175-2003 only allows the use of the cold-worked grades for down-hole tubulars. Precipitation-Hardenable Nickel Alloys

MR0103 includes all of the precipitation-hardenable nickel alloys that are listed in MR0175-2003 with the same material condition and maximum hardness requirements. In addition, MR0103 added N05500 and N07750, both of which were acceptable according to MR0175-2002 and previous revisions, but were intentionally omitted from MR0175-2003. The conditions and hardness limits for N05500 and N07750 are the same as those listed in MR0175-2002. Other Alloys

The requirements for cobalt-nickel-chromium-molybdenum alloys, cobalt-nickel-chromiumtungsten alloys, and titanium alloys are identical to those in MR0175-2002 and MR0175-2003 with one exception. Laboratory test data for solution annealed R31233 material indicates it has SSC resistance at hardness levels up to and including 33 HRC, so its hardness limit in MR0103 was set at 33 HRC maximum. The hardness limit for R31233 in all versions of MR0175 is 22 HRC maximum. MR0103 does not address the use of copper alloys or tantalum. Aluminum is only addressed for use in pistons and gaskets in Section 9 on Compressors and Pumps.

NACE CORROSION/2004 Paper 04649

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Fabrication

The fabrication section covers overlays; welding; cladding on carbon steels, alloy steels, and martensitic stainless steels; identification stamping; threading; and cold-deformation processes. With the exception of the coverage of cladding on carbon steels, alloy steels, and martensitic stainless steels, which is unique to the MR0103 document, these sections are essentially identical to, or very similar to, the corresponding sections in MR0175-2003. In MR0103, some of the information regarding welding and weld overlays in specific alloy groups has been incorporated into general sections covering those alloy groups. The cladding section was included because many refineries use cladding to prevent corrosion and SSC in less-resistant base materials. In order to meet MR0103, cladding materials must be selected from sections 2 or 3 of MR0103, and must be applied by hot rolling, explosion bonding, or weld overlaying. Some of the factors that influence the SSC resistance of clad components are listed for consideration by the end user. Because the evaluation of all of the relevant factors is outside the scope of MR0103, the end user is responsible for specifying whether the base metal must meet the requirements of MR0103. Bolting

The bolting requirements in MR0103 are only slightly modified from those listed in MR01752002 and MR0175-2003. There are a few editorial differences that provide clarification, but don't change the technical content. Two differences are the reference to special requirements for S17400 and S15500 when used for pressure bolting, and a warning statement indicating that zinc and cadmium coatings should not be used in sour environments because they enhance the generation of hydrogen on the surface, which can contribute to hydrogen cracking. Bolting was the subject of some good discussions during the generation and balloting of the document, especially regarding the subject of bolting that is under insulation. A number of refineries do not use special bolting grades (such as B7M) under insulation, and have not experienced problems even when gasket leaks have occurred. It is assumed that the lack of problems in these cases is due to the fact that insulation will not maintain enough pressure surrounding the bolting to result in the H2S partial pressure reaching a level that will promote SSC. Consensus was never reached on this topic during discussions, and the paragraphs were balloted and passed with wording that is essentially identical to that in the MR0175 documents. Plating, Coatings, and Diffusion Processes

The requirements listed in this section are identical to those in the MR0175 documents. In essence, these types of coatings are acceptable provided they are not utilized in an attempt to protect an otherwise unacceptable base metal.

NACE CORROSION/2004 Paper 04649

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Special Components

This section covers special requirements for certain types of components which often cannot be made from materials listed in the general materials sections of the document, such as bearings, springs, instrumentation and control devices, seal rings and gaskets, snap rings, and special process parts. The requirements listed in this section are identical to those in the corresponding sections of MR0175-2002 and MR0175-2003. Valves

The valves section simply states that new and reconditioned valves, including internal components, must be manufactured from materials meeting the requirements of section 2 or 3. Compressors and Pumps

In general, compressors and pumps must be manufactured from materials meeting the requirements of section 2 or 3. However, this section provides a few alternative materials for cylinders, liners, pistons, valves, gaskets, and impellers. ASTM A27823 Class 35 or 40 gray cast iron and ASTM A39524 ductile iron may be used for compressor cylinders, liners, pistons, and valves. Cast aluminum alloy ASTM B2625 A03550-T7 may be used for pistons. Gaskets may be made from aluminum, soft carbon steel, and soft, low-carbon iron. Impellers may be produced from UNS G43200 and a modified version of UNS G43200 that contains 0.28 to 0.33% carbon provided it is double-tempered at 621Â°C (1,150Â°F) minimum to produce a maximum yield strength of 620 MPa (90 ksi). CONCLUSIONS

From a practical standpoint it is expected that for downstream applications a broad range of users and authors of equipment standards will adopt the new MR0103 standard, in many cases replacing the current application of MR0175. It is expected that use of the environmental guidelines and material requirements of MR0103, together with NACE RP0472 for weld hardness control of P-No. 1 carbon steels, will be broadly applied to piping, valves, process contacted bolting, pumps, and compressors used in the sour service areas of the refinery process units listed in Table 3 in order to prevent SSC. MR-0103, applies for sour-service,

downstream/refining environments.

NACE CORROSION/2004 Paper 04649

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Table 3: Typical Refinery Equipment Susceptible to Sulfide Stress Cracking (Note: this list is not all-inclusive) Crude Unit â&#x20AC;&#x201C; Atmospheric Atmospheric Tower Coolers and Vacuum Overhead System Accumulators Vacuum Tower Overhead Coolers System Accumulators Debutanizers Light Ends Recovery Section Waste Gas Scrubbers Sour Water Collection System Catalytic Cracking Units Main Fractionator Overhead line Overhead System Coolers/Condensers Accumulators Coalescers Absorbers Wet Gas system Compressor Suction Drum Accumulators Coolers Deethanizers Light Ends Recovery Section Debutanizers Accumulators Hydro-Processing Units Feed System Feed Surge Drums Reactor Effluent Section High Pressure/Low Pressure Separators Trim Coolers Fractionation Section Stripper Towers Reflux Drums Gas Treating Section Amine Absorbers Off Gas Absorber Flash Tower Recycle Gas Systems Knock Out Pots Condensers Coker Units Coker Fractionator Similar to FCCU Overhead system Similar to FCCU Coker Light Ends Recovery Section Other Sour Water Recovery Units Sour Water Stripper Column Overhead system Amine Regenerator Amine Regenerator Tower Systems Accumulator Drum Quench Tower Gas Recovery Plants Similar to Light Ends Recovery above Sulfur Recovery Units Acid Gas Knock Out Drums Condensers Blow Down Drums

NACE CORROSION/2004 Paper 04649

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REFERENCES 1

NACE Standard MR0103-2003, “Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments” (Houston, TX: NACE). 2 NACE Standard MR0175-2002, “Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment” (Houston, TX: NACE). 3 NACE Standard MR0175-2003, “Metals for Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments” (Houston, TX: NACE). 4 API Standard 610, "Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries" (Washington, DC: American Petroleum Institute) 5 API Standard 617, "Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services" (Washington, DC: American Petroleum Institute) 6 API Standard 618, "Reciprocating Compressors for Petroleum, Chemical and Gas Industry Services" (Washington, DC: American Petroleum Institute) 7 NACE Standard RP0296 (latest revision), “Guidelines for Detection, Repair, and Mitigation of Cracking of Existing Petroleum Refinery Pressure Vessels in Wet H2S Environments” (Houston, TX: NACE) 8 NACE Publication 8X194 (latest revision), “Materials and Fabrication Practices for New Pressure Vessels Used in Wet H2S Refinery Service” (Houston, TX: NACE) 9 NACE Publication 8X294 (latest revision), “Review of Published Literature on Wet H2S Cracking of Steels Through 1989” (Houston, TX: NACE) 10 API Publication 581 (latest revision), "Base Resource Document - Risk-based Inspection" (Washington, DC: American Petroleum Institute) 11 ASME Boiler and Pressure Vessel Code, Section IX, Division I (latest revision), “Welding and Brazing Qualifications” (New York, NY: ASME) 12 ASTM A105/A105M (latest revision), “Standard Specification for Carbon Steel Forgings for Piping Applications” (West Conshohocken, PA: ASTM). 13 ASTM A216/A216M (latest revision) "Standard Specification for Steel Castings, Carbon, Suitable for Fusion Welding, for High- Temperature Service” (West Conshohocken, PA: ASTM). 14 ASTM A352/A352M (latest revision) "Standard Specification for Steel Castings, Ferritic and Martensitic, for Pressure-Containing Parts, Suitable for Low-Temperature Service" (West Conshohocken, PA: ASTM). 15 ASTM A516/A516M (latest revision) "Standard Specification for Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service" (West Conshohocken, PA: ASTM). 16 NACE Standard RP0472 (latest revision), “Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments” (Houston, TX: NACE) 17 R. N. Tuttle, "Selection of materials designed for use in a sour gas environment", in H2S Corrosion in Oil and Gas Production ~ A Compilation of Classic Papers, eds. R. N. Tuttle, R. D. Kane, (Houston, TX: NACE, 1981), p. 161. 18 ASTM A333/A333M (latest revision), "Standard Specification for Seamless and Welded Steel Pipe for Low-Temperature Service" (West Conshohocken, PA: ASTM). 19 ASTM A350/A350M (latest revision), “Standard Specification for Carbon and Low-Alloy Steel Forgings, Requiring Notch Toughness Testing for Piping Components” (West Conshohocken, PA: ASTM). 20 ANSI/NB-23, “National Board Inspection Code” (Columbus, Ohio: The National Board of Boiler and Pressure Vessel Inspectors). 21 Metals and Alloys in the Unified Numbering System (latest revision), a joint publication of ASTM International (ASTM) and the Society of Automotive Engineers Inc. (SAE), 400 Commonwealth Drive, Warrendale, PA 15096 22 ASTM A494/A494M (latest revision), “Standard Specifications for Castings, Nickel and Nickel Alloy” (West Conshohocken, PA: ASTM). 23 ASTM A278/A278M (latest revision), “Standard Specification for Gray Iron Castings for PressureContaining Parts for Temperatures Up to 650°F” (West Conshohocken, PA: ASTM). 24 ASTM A395/A395M (latest revision), “Standard Specification for Ferritic Ductile Iron PressureRetaining Castings for Use at Elevated Temperatures” (West Conshohocken, PA: ASTM). 25 ASTM B26/B26M (latest revision), “Standard Specification for Aluminum-Alloy Sand Castings” (West Conshohocken, PA: ASTM). NACE CORROSION/2004 Paper 04649

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NACE MR0103 & MR0175: A Brief History and Latest Requirements Ken Sundberg Metso VMA Technical Seminar San Antonio, TX March 5-6, 2015

NACE MR0175 & MR0103

INTERNAL

Overview

• NACE – A Look Back • Benefits to end-user • MR0103 & MR0175 Material Requirements, Limitations & Service Restrictions

Date Author Title

Current NACE Specifications

INTERNAL

• NACE MR0175/ISO 15156 – 2009 Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas Production - PART 1 - General principles for selection of cracking-resistant materials - PART 2 - Cracking-resistant carbon and low-alloy steels, and the use of cast irons - PART 3 - Cracking-resistant CRAs (corrosion resistant alloys) and other alloys - currently set to be revised again (2014 version)

• NACE MR0103 – 2012 Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments

Date Author Title

NACE – A Look Back

INTERNAL

Highlights

1930’s  Focus was on cathodic protection for underground pipes  The Mid-Continent Cathodic Protection Association (MCPA) held its first meeting on March 9, 1936 and met again on April 27, 1938

 Up until 1939, the MCPA operated separately, when they joined API as the Cathodic Protection Subcommittee

Date Author Title

NACE – A Look Back Highlights

1940’s  In 1940 the MCPA became affiliated with the Petroleum Industry Electronic Association (PIEA)

 In 1942, MCPA attempted to revise the bylaws, which were rejected by PIEA. This drove members of MCPA to consider forming an independent group, specifically addressing corrosion.

 Several meetings over the summer of 1943 were held and on October 10 & 11, 1943 the National Association of Corrosion Engineers (NACE) was formed.

 Sour gas and affects of the gas were experienced in the oil & gas industries starting in West Texas, Ginger Field in the late 1940’s to early 1950’s. 5

Date Author Title

INTERNAL

NACE – A Look Back

INTERNAL

Highlights, Con’t

Early 1950’s  The Canadian Jumping Pound and Pincher Fields came on experiencing similar issues with sour gas

 The Canadian failures were attributed to Sulfide Stress Cracking (SSC). o Considerable effort was put forth to understand and solve the Canadian failures, which would ultimately lead to safe and reliable production

 NACE formed the T-1G committee  The purpose of the committee was to gather data and attempt to solve the H2S cracking failures

o NOTE: Many on the committee feared that if there was a disastrous event that the government would step in and require its own controls. The government standard could also hinder discussions and developments which encouraged fluid and technical discussions.

Date Author Title

NACE – A Look Back

INTERNAL

Highlights, Con’t

1952  The T-1G committee held a SSC Symposium  Multiple papers were presented discussing ten (10) failures seen in the field.  They concluded that the failures resulted from improper material selection and how the material was processed, both of which made the materials vulnerable to H2S.

1962  The early committee work occurred in a Canada industry group that became T-1B  The T-1B section released a report that addressed material recommendations for sour gas service in well equipment



1963  NACE formed task group T-1F, which combined the activities of other task group activities

 They began to write valve document 1F166

Date Author Title

NACE – A Look Back

INTERNAL

Highlights, Con’t

1966  T-1F issued 1F166 – “Sulfide Cracking Resistant Materials for Valves for Production and Pipeline Service”

 1F166 consisted of o Production and pipeline valve document for wellhead valves up to 15,000 psi service

o Consistent manufacturing methods o Gate valve materials

1975  1F166 was transitioned into a Materials Requirement for Valves and issued as MR0175, which became an industry standard for Christmas tree valves

Date Author Title

NACE – A Look Back

INTERNAL

Highlights, Con’t

Between 1975 and 1978  Several SSC failures were experienced by the Texas Railroad Commission, which lead them to require MR0175 for all production equipment

 This became common throughout the refining industry up until MR0103 was issued

1978  Scope of MR0175 was expanded to include all equipment 1984  MR0175 stopped using material trade names and referenced UNS or SAE numbers (concerned with liable action if they limited the approved materials to the trade names)

Late 1990’s The scope of MR0175 was expanded to include SSC cracking caused by chlorides NACE approached ISO to create a global standard addressing sour environments combining the work done by NACE and European Federation of Corrosion (EFC)

Date Author Title

NACE – A Look Back Highlights, Con’t

2000  NACE task group 231 was formed to create a refinery standard for sour gas o Would later become MR0103

2002  By this time issues with MR0175 had accumulated since 1975 o High temperature SSC of the corrosion resistant alloy o Inconsistent alloy requirements o Unclear rules for alloys o Differing interpretations

Date Author Title

INTERNAL

NACE – A Look Back

INTERNAL

Highlights, Con’t

Early 2003 MR0175 splits into MR0175 & MR0103  MR0175-2003 o Intended for oilfield production where H2S and saltwater/brine was present o Many materials previously allowed were either discontinued or heavily restricted – Updated austenitic stainless steel requirements, which meant 300 series stainless steels may not meet the environmental requirements it once may have met

o Clarified welding requirements for carbon steels

 MR0103-2003 o Intended for sour refinery applications or other sour services but without saltwater/brine

o Very similar to MR0175 pre-2003

Date Author Title

NACE – A Look Back

INTERNAL

Highlights, Con’t

December 2003  NACE MR0175/ISO 15156 1ST Edition is issued  2004 to Present  Updates to MR0103 & MR0175/ISO15156 have consisted of adding or removing material requirements

Date Author Title

INTERNAL

NACE – A Look Back Highlights, Con’t: MR0175-2003 vs MR0103-2003 MR0175 2003 Addressed fact that oilfield applications tend to contain both Hydrogen Sulfide & Chlorides Old materials either removed or severely restricted

MR0103 2003 Refinery applications do not need protection from Chlorides

MR0175 Prior to 2003 Recommended materials for Hydrogen Sulfide services

Date Author Title

No change in allowed materials from old MR0175

NACE MR0175 & MR0103

INTERNAL

Benefit to the end-user

• Per MR0175/ISO 15156 the purpose is to provide “general principles and gives requirements and recommendations for the selection and qualification of metallic materials for service in equipment used in oil and gas production and in natural-gas sweetening plants in H2S-containing environments….” • Per MR0103, the purpose is to “establishes material requirements for resistance to SSC in sour petroleum refining and related processing environments containing H2S either as a gas or dissolved in an aqueous (liquid water) phase with or without the presence of hydrocarbon.” • In short, these standards reduce the risk of H2S related cracking failures in equipment • Benefits - Material requirements and recommendations for intended service - Minimizes health and safety accidents - Avoids equipment failures - Can extend the life of equipment that could have been subjected to H2S cracking 14

Date Author Title

INTERNAL

NACE MR0103 & MR0175 Material Requirements, Limitations & Service Restrictions Requirements & Limitations (general overview)

Material Requirements

Service Restrictions

ÂŠ Metso

NACE NACE MR0175 MR0103

Acceptable Materials

Hardness Limits

Heat Treatment Limitations

Material Condition Limitations

Chemical Compositions

Welding (Fabrication)

Exposed Bolting

Special Component Material Requirements

Environment Exposure Restrictions

Date Author Title

NACE MR0103 & MR0175

INTERNAL

Material Requirements, Limitations & Service Restrictions

• Not all of the requirements and limitations listed on the previous page are required for every material in every standard

• These standards only address material cracking in H2S environments • All other types of failure modes need to be addressed separately by end-user

• Allowable environmental conditions for approved uses -

MR0175 – environmental conditions are well defined MR0103 – as compared to MR0175 environmental conditions are not as well defined for the end-user. End-user judgment on conditions may be required. As an example, field experience of an unlisted alloy may be used as justification for its use

• End-user is responsible to determine: -

Operating conditions If their application falls within MR0175 or MR0103 If the material is satisfactory for a given service

Date Author Title

NACE MR0103 & MR0175

INTERNAL

Material Requirements, Limitations & Service Restrictions

• To fully specify valve compliant to NACE MR0175-2003 or newer version, the end-user must define the following environmental restrictions: - Max temperature - Max system pressure - Existence of elemental sulfur - Max chloride content - pH - Partial pressure of H2S - Will the valve be buried or insulated? • Manufacturer is responsible to comply with requirements set forth by end-user & to ensure the materials supplied to the end-user metallurgically comply with NACE standards • Purchasing a NACE compliant product only means the materials conform to NACE. It does not mean that the selected material is acceptable for all NACE MR0175 services. 17

Date Author Title

References

INTERNAL

• References:

•

D.H. Patrick, “MR0175 – A HISTORY AND DEVELOPMENT STUDY”, Paper No. 418, 1999

•

D. Bush, J. Brown & K. Lewis, “AN OVERVIEW OF NACE INTERNATIONAL MR0103 AND COMPARISON WITH MR0175”, Paper No. 04649, 2004

•

NACE, “NACE MR0175/ISO 15156 2009 2ND Edition”, NACE International Seminar, February 13, 2013

•

W. Brian Holtsbaum & Pierre Crevolin, “The History of NACE International The Corrosion Society, 1943-2013, 70 Years of Progress”, 2013

•

NACE MR0103, Multiple Versions

•

NACE MR0175, Multiple Versions

Date Author Title

www.metso.com

company/metso

metsoworld

metsogroup

metsoworld

metsogroup

Raising the Acceptance Level for Nickel in C-Mn steel Welds for Sour Service

PUBLISHABLE SUMMARY 16721

Background For C-Mn steel components requiring good low temperature toughness in the weld metal, nickel containing consumables are usually utilised. Presently, ISO 15156-2:2003 (MR0175) requires experimental demonstration of resistance to sulphide stress cracking (SSC) for C-Mn steel welds with more than 1%Ni in the deposit, despite work carried out in the 1980s which has been taken on board by DNV OS-F101. This standard allows up to 2.2%Ni. This work addressed the testing of weld metals containing more than 1%Ni in order to raise the relevant acceptance limits in ISO 15156.

TWI Ltd, Granta Park, Great Abington, Cambridge CB21 6AL, UK. Tel: +44 (0)1223 899000

Raising the Acceptance Level for Nickel in C-Mn steel Welds for Sour Service

Objectives 

Definition of the acceptability for sour service of C-Mn steel welding consumables with nickel contents in excess of 1%, but less than 2.5%.



Exploration of sour service performance of C-Mn steel consumables with nickel contents in excess of 2.5%, eg 3.5%Ni, which may be used for low temperature service

Project Outcome A number of reports were generated, including the test results and the findings relating to the suitability of higher Ni content weld metals in sour service.

Benefits 

Avoid design and fabrication restrictions related to overly conservative limitations on Ni content up to 2.5%, without compromising safety.



Savings will be obtained through avoidance of repeat testing for each individual project and by reducing the weld qualification time required for sour service applications.



Extension of acceptance to high Ni content 2.5-3.5% consumables will provide a wider range of options to allow optimised design, fabrication and repair.

Participants The Sponsor Group comprised: 

ENI S.p.A



Technip USA Inc



Shell UK Ltd

Scope of Work The work undertaken comprised metallographic examination and hardness testing of the welds, determination of retained austenite, chemical analysis, plain four point bend testing in the NACE Solution A environment and KISSC testing in the NACE Solution A environment and in a milder sour environment.

Price and Duration The project had a duration of 2 years and a budget of £180,000. It was funded by 3 Sponsors each making a contribution of £60,000. The fee for additional companies buying-back into the project results is £60,000

Further Information For further information on Joint Industry Projects (JIP) and their operation, please visit: http://www.twi.co.uk/services/research-and-consultancy/joint-industry-projects/ JIP Co-ordinator: Tracey Stocks

Ref: 16721/10-1/15

Email: jip@twi.co.uk Project Leader: Joanna Nicholas Email: Joanna.nicholas@twi.co.uk

TWI Ltd, Granta Park, Great Abington, Cambridge CB21 6AL, UK. Tel: +44 (0)1223 899000

THE HEAT TREAT DOCTOR •

•

rial H

Daniel H. Herring | 630.834.3017 | dherring@heat-treat-doctor.com

A Discussion of Retained Austenite hat is retained austenite and how does it affect the properties of a component? How much, if any, retained austenite should be present in a particular component microstructure? Is the presence of retained austenite in a microstructure a good thing or a concern? These are questions that metallurgists have spent countless hours debating. What do we as heat treaters need to know about retained austenite and how is retained austenite viewed by various industries? Let's learn more. What is retained austenite? Austenite that does not transform to martensite upon quenching is called retained austenite (RA). Thus, retained austenite occurs when steel is not quenched to the Mf, or martensite finish,

Fig. 1. RA present in a case carburized component [1]. Photomicrograph courtesy of Alan Stone, Aston Metallurgical Services (www.astonmet.com). Etchant: 2% nital. 1,000×

14 March 2005 – IndustrialHeating.com

temperature; that is, low enough to form 100% martensite. Because the Mf is below room temperature in alloys containing more than 0.30% carbon, significant amounts of untransformed, or retained austenite, may be present, intermingled with martensite at room temperature (Fig. 1). Retained austenite is a specific crystalline form of iron and steel. The dark-colored needles shown are tempered martensite crystals and the light-colored areas are retained austenite crystals. The amount of retained austenite is a function of the carbon content, alloy content (especially nickel and manganese), quenchant temperature and subsequent thermal and/or mechanical treatments. Depending on the steel chemistry and specific heat treatment, the retained austenite level in the case can vary from over 50% of the structure to nearly zero. While large amounts of retained austenite (>15%) can be detected and estimated by optical microscopy, specialized equipment and techniques, such as x-ray diffraction methods, are required to accurately measure the amount of retained austenite to as low as 0.5%. Why is retained austenite problematic? The very characteristics that give retained austenite many of its unique properties are those responsible for significant problems in most applications. We know that austenite is the normal phase of steel at high temperatures, but not at room temperature. Because retained austenite exists outside of its normal temperature range, it is metastable. This means that when given the opportunity, it will change or transform from austenite into martensite. In addition, a volume change (increase) accompanies this transformation and induces a great deal of internal stress in a component, often manifesting itself as cracks.

How does RA behave? Martensite is hard, strong and brittle while austenite is soft and tough. In some instances, when combined, the mixture of austenite and martensite creates a composite material that has some of the benefits of each, while compensating for the shortcomings of both. For any given application, mechanical properties are affected by a high percentage of retained austenite content. For example, retained austenite affects the following properties of bearing steels: • Dimensional stability: Retained austenite will transform to martensite if the temperature drops significantly below the lowest temperature to which it was quenched, or if the room temperature austenite is subjected to high levels of mechanical stress. Martensite, a body centered tetragonal crystal structure, has a larger volume than the face centered cubic austenite that it replaces. Where transformation occurs, there will be a localized 4-5% increase in the volume of the microstructure at room temperature and a resulting dimensional change in the geometry of the component. If great enough, this dimensional change could lead to growth and in severe instances, crack initiation. • Fatigue: Low retained austenite content and fine austenitic grain sizes, which create a microstructure of finely dispersed retained austenite and tempered martensite, prevent nucleation of fatigue cracks, or retard fatigue crack initiation until very high stress levels are reached. In contrast, low-stress applications that fracture at low cycles are related to high retained austenite levels and coarse austenite grain sizes. For example, one type of fatigue strength of interest

rial H

•

Dimensional Stability Higher Fatigue Lower strength Impact Lower strength 0%

B A L A N C E

Lower

Higher

20% 40% Increasing retained austenite content

to many users is rolling contact fatigue. Two aspects of retained austenite can improve rolling contact fatigue life. First, the inherent ductility of retained austenite helps to delay crack growth by blunting the tips of cracks as they form. Second, as retained austenite transforms during service, compressive residual stresses increase in the case. These compressive stresses delay crack growth by functioning like a vise and clamping cracks closed. These benefits are not present in a part with insufficient retained austenite. • Impact: Impact strength is the measure of the ability of a steel to resist fracture when subjected to a sharp blow. Austenite is not only very tough, but also it has higher impact strength than martensite. The steel's impact strength increases with increasing austenite content. Higher impact strength can provide extra protection against cracking, which, in turn, helps prevent such problems as spalling. It is important to recognize that a balance must be created between the mechanical properties of a component and the optimum percentage of retained austenite for a given application (Fig. 2). How some industries view retained austenite Retained austenite is highly undesirable in components for the tool and die industry. RA is recognized as a major cause for premature failure. The low hardness of RA is also incompatible with most applications that require the maximum attainable hard16 March 2005 – IndustrialHeating.com

Fig. 2. (left) Balancing properties and RA content [2] Fig. 3. (above) Gear tooth failure due to spalling (macropitting)

ness to resist wear. The bearing and gear industries have a more favorable view toward having some retained austenite (5 to 30% determined by optical metallography, usually by comparison to known standards). While some of the same mechanisms that affect tooling applications also affect gears, there are some major differences. Gears are typically made of case-hardened steel, which has high impact strength. While most tools fail by wear or fracture, many gear failures are the result of spalling in the tooth area. Spalling is progressive macropitting that occurs when pits coalesce and form irregular craters, which cover a significant area of the tooth surface (Fig. 3). Spalling occurs when the surface of a metal component is subjected to repeated cyclic loads. A crack forms and grows until a small portion of the surface breaks loose, damaging the surface and adding debris to the system. The gear industry balances the amount of retained austenite in a gear tooth to delay the onset of spalling by suppressing crack growth. How is the percentage of RA reduced? Tempering is one method used to transform retained austenite. A key is to hold for an adequate amount of time at temperature. Multiple tempers are often performed to ensure the maximum amount of retained austenite has been transformed. Other popular methods include cold treatment at 120ºF (-85ºC) or cryogenic treatment to 320ºF (-195ºC). It is well documented that as the temperature is lowered the degree of transformation increases.

Conclusion By controlling the level of retained austenite, its beneficial effects can be realized without suffering from its negative influences, such as excessive dimensional growth. Many industries have found a “sweet spot” exists for retained austenite content to achieve a balance of fatigue/impact strength and dimensional stability. To obtain the optimum level of retained austenite requires a delicate balance of controls and must take into account such items as material chemistry and heat treatment process variables. These variables include steel chemistry, carbon content, austenitizing temperature, quenching rate and tempering temperature. IH References • Private correspondence, Technical Forum 00-1 Retained Austenite: It's Impact on Bearing Performance, BRENCO Inc. (www.brencoqbs.com) • Krauss, G., Steels: Heat Treatment and Processing Principles, ASM International, 1990 • Private correspondence, Dr. Jeff Levine, Applied Cryogenics (781-270-1180)

Additional related information may be found by searching for these (and other) key words/terms via BNP Media LINX at www.industrialheating.com: retained austenite, metastable, untransformed austenite, martensite finish temperature, dimensional stability, rolling contact fatigue, impact strength, spalling, macropitting, tempering, cryogenic treatment.

Retained Austenite Stabilization Case-hardened components made of low-alloy steels often have retained austenite in the case after quenching, which can be transformed to martensite by further cooling of the component, even if the austenite stabilizes during aging at room temperature.

he phenomenon of retained austenite stabilization in tool steels is well documented [1,2]. When a steel with a martensite finish temperature (Mf) below room temperature is quenched, some austenite is retained in the microstructure. If cooling is immediately continued to a temperature below the Mf, virtually all the austenite present at room temperature can be transformed to martensite. However, if there is a delay between quenching to room temperature and the further cooling, the austenite can stabilize and cannot then be transformed by subsequent cooling [3]. It is important to know if this phenomenon also applies to carburized low alloy steels used to make gears. As well as reducing hardness and wear resistance, retained austenite in the case of such components

can later be transformed by applied stress, causing distortion during service. Retained austenite has also been reported to lead to cracking during grinding after heat treatment. There is no agreement in the literature on the occurrence of stabilization, with some reports suggesting that it does not occur in carburized low alloy steels [4]. Others, however, report that it does occur [5, 6]; and some even suggest that its onset is very rapid [7]. Where stabilization is reported, it is generally associated with high alloy content, particularly nickel, and with the presence of nitrogen in the case. The work reported here set out to show the effects of stabilization on a typical carburizing steel (SAE 8620) after carburizing in a typical industrial cycle without any added nitrogen.

By Paul Stratton and Cord Henrik Surberg

juLY 2009

Fig. 1: Hardness profiles after cold treatment with different time delays.

Table 1 — Properties of the case before and after cold treatment Treatment As quenched Cold after 2 min Cold after 1h Cold after 12 h Cold after 24 h Cold after 168 h

Case depth at 550 HV, mm 0.93 1.01 1.07 0.97 1.02 0.88

Surface hardness, HV1 @ 0.1 mm 827 951 997 901 956 953

Retained austenite, % 27.4 10.4 8.8 11.3 11.6 9.4

Experimental Conditions The SAE 8620 material for the tests was in the form of gear teeth. They were carburized in an industrial sealed quench furnace with the following cycle: •H eat to 930°C with a carbon potential of 0.4 percent and soak for more than 190 minutes. • C arburize at 930°C for 345 minutes at a carbon potential of 0.9 percent. • D iffuse at 850°C for 150 min at a carbon potential of 0.75 percent. • O il quench until the samples reach 70°C. • C old treat at -120°C for 1 hour, after delays of 2 minutes, 1 hour, 12 hours, 24 hours, and 168 hours. After treatment, each sample was examined for microstructure, retained austenite (by x-ray diffraction) and hardness profile.

Testing Results

Fig. 2: Microstructure of the near-surface case before and after cold treatment; (top) as-quenched; (middle) cold treated after 2 min; (bottom) cold treated after 168 h.

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The hardness profiles for the different delay times are shown in fig. l. Photomicrographs of the case for one of the as-quenched samples that was cold treated within two minutes of quench and one cold treated after a delay of l68 hours are shown in fig. 2. The structure within 20 µm of the surface has been affected by the migration of alloying elements through

internal oxidation, which is normal for carburizing treatments carried out in endothermically generated atmospheres. There is no visible difference between the sample cold treated after two minutes and that cold treated after l68 hours. The case depths obtained from the hardness traverses, the surface hardness, and the retained austenite levels obtained by x-ray diffraction are summarized in table 1.

Discussion of Test Results Retained austenite is thought to be stabilized by a pinning mechanism. During aging, carbon is redistributed by diffusion out of the martensite. The structure is then stabilized by interstitial carbon atoms pinning the austenitemartensite interface [5]. As pinning increases with the length of time after quenching, more energy is needed to restart the transformation to martensite; i.e., a lower cold treatment temperature is needed [8]. In general terms, some alloying additions are known to promote stabilization, particularly nickel, carbon, and nitrogen [5, 9]. Thus, the austenite in the cases of higher alloy carburizing steel with high carbon or carbonitrided cases will have a greater tendency to stabilize. In industrial practice, the transformation temperature available is fixed and the stabilization effect is usually characterized by the time until the available cold treatment temperature will be able to restart the transformation. Assessing reports on the stabilization time must therefore take into account not only the composition of the austenite, but the cold treatment temperature used. In the case of SAE 8620, under the experimental conditions using cold treatment at -120°C, this temperature was sufficient to restart transformation after all the stabilization times tested. This effect probably explains the disparity in the results found in the literature. It is likely that for low alloy carburizing steel, -120°C will always be sufficient to restart transformation, but any higher temperature may not be.

References:

Fig. 3: The effect of various cold treatment temperatures on the retained austenite in the case of SAE 8620 after l,680 h of stabilization. To test this theory, a second as-quenched sample gear was allowed to stabilize for 1,680 hours, and was then subjected to cold treatment at temperatures in the range -40 to -120°C for one hour. The results are shown in fig. 3. Although not completely conclusive, as the same effect might have been found in samples immediately after quench, the results suggest that a cold treatment temperature of between -40 and -70°C was needed to restart transformation in this steel. The quantity of retained austenite in this second sample gear in the as- quenched condition was found to be significantly lower than in the original sample gear, when it was tested shortly after quenching. To check if the retained austenite could have been reduced as a result of the time that elapsed between the two measurements, a second sample from this gear was checked. This sample was also found to contain less retained austenite (15.8 percent). To confirm that this was not simply a difference between the two gears, a sample from the first gear was retested and was found to contain 19 percent retained austenite, significantly less than when it was originally tested. The microstructure (fig. 4) appears to contain some small bainite laths that could have formed during extended aging at room temperature. This suggests that the effect is real and is probably caused by isothermally reaching the bainite start condition after protracted aging at room temperature.

Conclusions For carburized SAE 8620, cold treatment at -120°C is sufficient to restart the transformation of retained austenite to martensite after any stabilization period. The temperature necessary to restart the transformation after stabilization is probably in the range -40 to -70°C.

Fig. 4: Microstructure of the case of a sample aged for 1,680 h at room temperature.

Recommendations The results of this study were combined with a review of the available literature to develop a number of recommendations for best industrial practice for the cold treatment of case carburized components to remove retained austenite. It is obviously impractical to test every carburizing steel over a range of case compositions and available cold treatment temperatures, so the following guidelines can be used: •T he higher the alloy content (particularly nickel), the shorter the stabilization time and the lower the cold treatment temperature that should be used. • T he higher the case carbon content, the shorter the stabilization time and the lower the cold treatment temperature that should be used. Preemptive treatment of all components is preferable to attempting to recover components after over carburizing is discovered. • T he shorter the delay between quenching and cold treatment the better. • T he colder the treatment temperature the better.

1) H eat Treaters Guide, Practices & Procedures for Irons and Steels, ASM International, 1995. 2) Totten G.E., Xie L., and Funatani K., Handbook of Mechanical Alloy Design, CRC Press, p 236, 2004. 3) S mallman R.E., Modern Physical Metallurgy, London, Butterworth, p 329, 1962. 4) Moore C., Development of the BOC Ellenite process (cold treatment of metals with liquid nitrogen). Heat Treatment ‘73, The Metals Society, Book No. 163, p 157-161, 1975. 5) Abudaia F.B., On the Stabilisation of Retained Austenite, Journal of Engineering Research, Issue 5, 6, March 2006. 6) S urberg C.H., Stratton P., and Lingenhöle K., The effect of deep cold treatment on two case hardening steels, Acta Metallurgia Sinica, 21 (1),1-7, 2008. 7) Lynwander P., Gear Drive Systems: Design and Application, CRC Press, p 255, 1983. 8) Xie Z.L., Liu Y., and Haenninen H., Stabilization of retained austenite due to partial martensitic transformations, Acta Metallurgica et Materialia, 42(12): 4117-4133, 1994. 9) Kim S-J, Lee CJ, Lee T-H, and Oh C-S, Effect of Cu, Cr and Ni on mechanical properties of 0.15 wt% C TRIP-aided cold rolled steels, Scripta Materialia, 48(5), p 539544, 2003.

About the authors: Paul Stratton is with The Linde Group and can be reached at paul.stratton@boc.com. to

Also

[www.boc-gases.com].

go Cord

Henrik Surberg is at the V-Research Center of Competence for Tribology and Technical Logistics GmbH in Dornbirn, Austria.

juLY 2009

By Don Bush

Welding of Carbon Steel Materials for Use in Sour Service

Valve manufacturers often are required to provide valves for use in wet H2S, or â&#x20AC;&#x153;sourâ&#x20AC;? environments. While NACE MR0175 is commonly specified for valve constructions destined for sour oil or gas production applications, there are several other industry standards that document appropriate materials and processing practices for sour services. In the case of carbon steels, these documents provide much more detailed information than MR0175.

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Valve manufacturers are commonly required to provide valves for use in environments containing hydrogen sulfide (H2S) and water, environments that are often referred to as “sour”. NACE MR0175, Material Requirement - Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment, is usually specified for valve constructions destined for sour oil or gas production applications. However, there are several other industry standards and reports that document appropriate materials and processing practices for materials for sour services. In the case of carbon steels, these documents provide much more detailed information than MR0175. This article provides a brief background on sulfide stress cracking, summarizes metallurgical considerations related to carbon steel weldments, and provides an overview of some of the key points in NACE RP0472 and NACE Committee Report 8F192.

Sulfide Stress Cracking and Wet H2S Cracking Mechanism In essence, steels above a certain hardness are susceptible to a phenomenon known as hydrogen embrittlement. Hydrogen embrittlement is defined as “a condition of low ductility in metals resulting from the absorption of hydrogen.”1 Hydrogen embrittlement is mainly a problem in steels with ultimate tensile strength greater than 90 ksi, and is usually manifested by delayed, catastrophic, brittle fracture at tensile stresses well below the ultimate tensile strength of the material. When steel corrodes in an environment containing water and H2S, the H2S breaks down to form H+ ions and S- ions. Since H+ ions are much smaller than H2 molecules, they can easily diffuse into steels at ambient temperatures. The S- ions react with the steel surface to form a porous iron sulfide layer. This iron sulfide layer catalyzes the absorption of H+ ions into the steel, resulting in a higher degree of hydrogen charging than would occur in an environment with H+ ions and no catalyst. Cracking in the presence of H2S corrosion is usually called “sulfide stress cracking” in the oil and gas production industry, and “wet H2S cracking” in the oil refining industry. The term “wet H2S cracking” is more descriptive of the actual mechanism and will be used throughout the remainder of this article. In order for wet H2S cracking to occur, three conditions must be met: 1. The hardness/strength of the material must be above a threshold value; 2. The hydrogen concentration in the steel must achieve a threshold value; and 3. The material must be subjected to a tensile stress above a threshold value. In all cases, all of these factors are interrelated. In other words, as the value of one factor increases, the threshold value 2

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of the other factors decreases. There are no well-established rules regarding these interrelationships. However, guidelines have been developed with respect to H2S content in the process fluid. If the H2S content and certain other factors are met (such as the presence of liquid water), the application is deemed to be “sour”. Guidelines have also been developed for materials and material conditions that are acceptable for sour applications. The most widely known guideline document is NACE MR0175. NACE MR0175 restricts carbon steels to a maximum hardness of 22 Rockwell “C” (HRC), and to the following heat treat conditions: (a) hot-rolled (b) annealed (c) normalized (d) normalized and tempered (e) normalized, austenitized, quenched, and tempered (f) austenitized, quenched, and tempered. The standard mechanical property requirements for the typical carbon steel pressure vessel materials, such as ASME SA216 WCB, WCC, LCB, and LCC castings, SA105 and SA350 LF2 forgings, SA515 Grade 70 and SA516 Grade 70 plate, etc., essentially ensure that the bulk properties will meet MR0175 requirements.

Why Weldments Are a Concern Carbon steels are all hardenable by heat treatment to some degree. Carbon steels are hardened by a two-step heat treating process known as austenitizing and quenching. The austenitizing phase involves heating the steel to above a critical temperature, which changes it from its ambienttemperature equilibrium structure (ferrite and pearlite in the case of carbon steels) to an austenitic structure. Quenching involves cooling the steel at a rate that is rapid enough to prevent the formation of the ferrite and pearlite equilibrium microstructure. The structure that is formed is a metastable atomic arrangement called martensite. Martensite is very hard and strong, but is generally somewhat brittle. A further operation, called tempering, is often performed after austenitizing and quenching. Tempering involves heating the steel to a temperature below the critical temperature, which causes the formation of a softer, tougher microstructure that is weaker than the untempered martensite, but stronger than the equilibrium ferrite and pearlite structure. The maximum hardness that can be achieved by a particular steel, referred to here as the hardness potential, is strongly dependent upon the carbon content. Alloying elements, such as chromium, nickel, molybdenum, manganese, etc., generally serve to increase the hardness potential, but to a much lesser degree than the carbon content.

On the other hand, the ease with which the hardness potential is realized upon quenching, known as hardenability, is heavily influenced by alloying elements other than carbon. For example, a steel with 0.22% carbon has a hardness potential of well over 50 HRC. However, only very thin sections of strip or small wire can be quenched in water rapidly enough to form 100% martensite and achieve the hardness potential in a plain carbon steel. The addition of small amounts of manganese, chromium, nickel, molybdenum, and other elements increases hardenability tremendously. The effects of alloying elements are so dramatic that steels with only two percent alloying elements can form fully martensitic structures when air-cooled from the austenitizing temperature. The reason that heat treatment of steels is pertinent to welding is that the deposited weld filler metal, and the heataffected zone (HAZ) in the base metal, undergo this same type of “heat treatment” during the welding process. As a weld deposit is produced, the deposit starts as a molten puddle. The puddle quickly solidifies as heat is transferred to the surrounding base metal. Immediately after solidification, the weld deposit is well above the critical temperature. In addition, the base metal immediately adjacent is also heated to above the critical temperature. As the weldment cools by heat transfer into the surrounding base metal and atmosphere, the weldment is being “quenched”. The actual cooling rate is dependent upon a number of factors, including: • The size of the weld deposit (smaller size = faster cooling); • The mass of the base metal (larger/heavier = faster cooling); and • The temperature of the base metal (cooler = faster cooling). Because of this built-in quenching process, weldments can potentially contain localized hard regions in the weld deposit, the HAZ, or both.

Chemistry Controls vs. Weldment Hardness The as-welded hardness achieved in the weld deposit and the HAZ is dependent upon three factors: 1. The hardness potential of the material (weld filler and base metal); 2. The hardenability of the material (weld filler and base metal); and 3. The cooling rate. If the right (or wrong) combination of hardness potential, hardenability, and cooling rate exist, high hardness can occur in as-welded deposits and/or in the HAZ. Restricting the maximum carbon content to a lower value than that normally allowed for the material (example: 0.22% maximum carbon vs. the normal 0.25% maximum carbon for WCC) reduces the hardness potential for the material. In

other words, the maximum hardness the weldment could possibly achieve in the as-welded condition is lower. The carbon equivalent (CE) is defined by the following equation: CE = %C +

%Mn (%Ni + %Cu) (%Cr + %Mo + %V) + + 6 15 5

The carbon equivalent attempts to account for both hardness potential and hardenability in one parameter that can be used to assess weldability of steels. Thus, controlling the CE to a lower value reduces the likelihood of hard regions in the as-welded condition under a given set of welding conditions. The cooling rate is affected by part configuration and welding parameters. Carbon content restriction and CE limits do not affect cooling rate.

Industry Standards for Wet H2S Cracking Prevention in Carbon Steels The potential for hard zones in weldments has been recognized in both the oil and gas production industry and the oil refining industry. The production industry’s document, NACE MR0175, contains the following paragraph pertaining to this issue: “5.3.1.2 Welding procedure qualifications on carbon steels that use controls other than thermal stress relieving to control the hardness of the weldment shall also include a hardness traverse across the weld, HAZ, and base metal to ensure that the procedure is capable of producing a hardness of 22 HRC maximum in the condition in which it is used.” Some manufacturers and users interpret this paragraph to mean that any procedure qualification that includes hardness readings in the weld deposit, HAZ, and base metal meets the intent of the paragraph above. However, the important words in the above paragraph are not those regarding the hardness traverse, but rather the words “use controls other than stress relieving”. Whereas the specific controls that may be required are left up to the manufacturer, some type of extra control measures are implied. The ASME construction codes (ASME Boiler and Pressure Vessel Code, ASME B31.1 Power Piping, ASME B31.3 Process Piping, and ASME B31.5 Refrigeration Piping) provide rules that govern PWHT of carbon steel weldments based upon the section thickness being welded. Thinner sections may be welded without PWHT, whereas thicker sections (actual limits vary by specific code) require PWHT. Unfortunately, the ASME codes don’t require any correlation between the carbon content or CE level of the PQR specimen and that of the production base metal. In other words, it is SUMMER 2000

perfectly acceptable within the ASME codes to utilize a PQR specimen with 0.12% carbon and a CE of 0.35 to qualify a non-PWHT procedure for welding any P-1 material. This is in spite of the fact that some P-1 materials have maximum carbon contents of 0.35% and can produce CE values exceeding 0.60. Thus, it is logical that the “controls other than stress relieving” mentioned in MR0175 would likely need to include some type of correlation between the carbon content or CE level of the PQR specimen and that of the production base metal. In addition, the term “hardness traverse” is not defined in MR0175. In general, a hardness traverse consists of a series of hardness indentations regularly spaced along a line. In weldments, hardness traverses are generally run along lines that are parallel to the surface of the base metal. Lines are generally located just below the surface (common values are 1 mm or 0.060" below the base metal surface), through root passes, and/or through the weldment at the centerline of the base metal thickness. Hardness measurements at random locations in the three zones do not constitute a hardness traverse, but rather represent a “hardness survey”. Finally, most user specifications that actually define the hardness traverse require that reading be taken using 10kg Vickers or Rockwell 15N scale so the readings will be more sensitive to local hard spots than if Rockwell “C” or Brinell scales were utilized. The refinery industry’s document, “NACE RP0472, Recommended Practice - Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments,” contains various alternative methods that can be followed to assure that carbon steel weldments will be soft enough to resist cracking.2 To summarize briefly, the document deals with two separate issues—weld deposit hardness and base metal heataffected zone hardness. Weld deposit hardness is addressed as follows: —The accepted method is to perform portable Brinell tests on weld deposits to ensure that they meet a 200 HB maximum requirement. The weld deposit hardness testing requirement is waived when the SMAW welding process is used with E60XX or E70XX fillers or when the GTAW welding process is used with ER70S-X fillers (other than -6, -7, or -G grades). Although RP0472 does not specifically address postweld heat treatment (PWHT) as a means for controlling weld deposit hardness, it is generally recognized as an effective method. The PWHT method involves tempering at a temperature high enough to reduce hardness and relieve residual welding stresses via high-temperature stress relaxation. Thus, PWHT has a positive effect on two of the three factors influencing wet H2S cracking. PWHT is effective at reducing the hardness of nearly any carbon steel weld deposit 4

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to well below the hardness levels recommended to prevent wet H2S cracking.3 However, RP0472 cautions that the practice of postweld heat treating at lower temperatures for longer times, as allowed by some of the ASME Codes, should not be followed when the heat treatment is being performed to reduce the hardness of the weld deposit or the heat-affected zone. There are three methods listed in RP0472 for control of base metal heat-affected zone hardness: • Chemistry control (specifically, control of the maximum carbon equivalent); • Weld procedure qualification hardness testing, including less-restrictive chemistry control in conjunction with special welding process controls; and • Postweld heat treatment (PWHT), also commonly called stress relieving. The chemistry control method involves selection of filler metal chemistry in conjunction with control of the base metal carbon equivalent to such a low level that low weld deposit hardness and HAZ hardness is virtually guaranteed regardless of welding process parameters. NACE Committee Report 8X1944 states that a CE of 0.43 is commonly specified for base materials when this technique is employed. The weld procedure qualification hardness testing method is a variant of the chemistry control method. In this method, a less restrictive maximum CE value may be chosen for production base metal. A welding procedure qualification record (PQR) test specimen is then created using actual production material or a coupon of representative material with an actual CE corresponding to the maximum CE value that is to be applied to the production base material. Welding variables (such as preheat, current, voltage, travel speed, interpass temperature, etc.) are controlled and monitored closely during the creation of the procedure qualification specimen. The PQR tests include a hardness traverse using either 10kg Vickers or Rockwell 15N scale. Predefined hardness traverse diagrams are provided for several weld geometries (See Figure 1). The resulting welding procedure specification (WPS) then must contain certain restrictions to ensure that the PQR specimen is actually representative of production weldments. Those restrictions include: • The procedure may only be used with the same base metal grade and class. In other words, a procedure qualified on A516 Grade 60 plate material could not be used to weld A516 Grade 70 plate material or A216 Grade WCC castings, even though all are within the same ASME Section IX P-Number group. • The actual CE of production material must be controlled to a value less than or equal to that of the PQR specimen. • The heat input used during production welding must not

deviate from the heat input used during creation of the PQR specimen by more than 10% lower or 25% higher (alternatively, for the shielded metal arc welding (SMAW) process, the maximum bead size and the minimum length of weld bead per unit length of electrode used in creation of the PQR specimen can be imposed as a requirement in the WPS). • Preheat and interpass temperatures must be at least as high as those utilized in production of the PQR specimen. • If preheat was not utilized for the PQR specimen, the maximum base metal thickness of production weldments must not be allowed to exceed the thickness of the PQR specimen. • Other restrictions apply to fillet welds, submerged-arc welding (SAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW) processes, welding procedures involving bead-tempering techniques and other techniques that are sensitive to weld-bead sequence, and materials containing intentional additions of microalloying elements such as Nb (Cb), V, Ti, and B. The postweld heat treatment (PWHT) method involves tempering at a temperature high enough to reduce hardness and relieve residual welding stresses via high-temperature stress relaxation. Thus, PWHT has a positive effect on two of the three factors influencing wet H2S cracking. Furthermore, except in cases where carbon steel base metals are intentionally micro-alloyed with certain strengthening elements, PWHT is effective at reducing the hardness of any welded carbon steel pressure vessel material to well below the hardness levels recommended to prevent wet H2S cracking. Again, RP0472 cautions that the practice of postweld heat treating at lower temperatures for longer times, as allowed by some of the ASME Codes, should not be followed when the heat treatment is being performed to reduce the hardness of the weld deposit or the heat-affected zone.

Discussion and Comparison of Methods Products procured for new oil and gas facilities, expansions, and/or repairs often are governed by customer or contractor piping specifications. These specifications may contain stipulations requiring maximum CE values for all components in the piping system, and these requirements are often imposed on valves. The use of these special chemistry controls allows the company and/or its contractors to perform welding on components without PWHT and be reasonably sure that weld heat affected zones will be soft enough to resist wet H2S cracking. This is especially useful for components that will be actually welded into the system, although it is also beneficial for non-welding-end components that may eventually require welding to repair erosion or corrosion damage. The special chemistry control approach works very well for pipe and for vessels fabricated from plate materials, where it is

Butt Weld

Fillet Weld Figure 1: Schematics from NACE RP0472 showing suggested locations for hardness traverse indentations. Copyright 1995 by NACE International. All rights reserved by NACE: reprinted by permission. NACE standards are revised periodically. Users are cautioned to obtain the latest edition; information in an outdated version of the standard may not be accurate.

often difficult to perform postweld heat treatment. Economically, it is often not that expensive to use special materials for these applications because entire mill runs of material will be specifically produced to satisfy the order for raw material. On the other hand, most valves are made from castings. In most cases, a special order for controlled CE does not comprise an entire heat of material. This increases the cost and lead time of the castings significantly, since a special heat must be prepared. In addition, it is difficult to procure custom forgings and other wrought products often used in valve fabrications with special CE limits because most vendors supplying these materials to valve companies don’t make their own raw materials. Rather, must search for raw materials that meet the special requirements. In addition, most valves are designed to be used in a multitude of applications in a wide variety of industries—oil and gas, electric power, chemical, pulp and paper, etc. Weldment hardness is not as critical an issue in general applications as it is in wet H2S applications. Therefore, it isn’t SUMMER 2000

Hardness Control Method

Low CE Controls on Base Metal (eg.: 0.43 max CE)

Weld Procedure Qualification Hardness Testing + Intermediate CE Control on Base Metal + Welding Process Controls

Postweld Heat Treatment

Material cost

Highest cost

Higher cost

Standard cost

Lead time

Longest lead time

Longer lead time

Standard lead time

Welding controls

Standard welding controls

Very restrictive welding controls. Heat input control requirements may be very difficult to maintain with manual welding processes.

Standard welding controls

PWHT

Not required

Required

Resulting weld deposit hardness

Acceptable, provided proper filler metals are utilized

Lower than other methods

Weld deposit hardness tests

Required except for some SMAW and GTAW welds

Not necessary

Resulting HAZ hardness

Acceptable, intermediate hardnesses

Acceptable, likely higher Acceptable, lowest hardnesses than other methods hardnesses of all methods

Residual stress level

Higher

Lower

Weld repairs to correct erosion or corrosion damage

Require no PWHT or special welding process controls

Require postweld heat treatment(a)

Require postweld heat treatment

Weld deposit hardness tests on weld repairs

Should be performed except for some SMAW and GTAW welds(b)

Not necessary (assuming PWHT is performed)

Not necessary

Residual stress level adjacent to repairs

Higher

Lower

( a)

Assumes weld repairs performed by refinery or contract welders will not be performed with special welding procedures developed for intermediate carbon and/or CE controlled chemistry

(b)

Since PWHT will not be performed, hardness testing would be prudent when utilizing fillers which would normally be tested. However, hardness testing of erosion or corrosion repair welds is often difficult or impossible because they are usually located internally.

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economically attractive to standardize on a special, more expensive casting chemistry to accommodate the small percentage of valves that are destined for sour service. With respect to valves that are not weld-end products (such as flanged, wafer, and screwed-end valves), special compositional restrictions are only beneficial if the valves ever require welding. During manufacture of the valve, welding may be performed either for fabrication purposes or to repair casting or machining defects. In most cases, it is probably less expensive to postweld heat treat welded valves destined for sour service than to purchase special chemistries that would allow welding without PWHT. After the valves have been in service, welding may be utilized to repair erosion or corrosion damage. Again, in many cases, it may actually be more economical to postweld heat treat repairs or, in the case of smaller valves, simply replace the valves, than to purchase special chemistry controls in the original valves. Finally, postweld heat treatment provides the additional benefit of reducing residual stresses in the weld deposit, the heat-affected zone, and the adjacent base metal. Therefore, in addition to providing lower hardnesses than the other methods, it also reduces overall stresses in the weldment, which further enhances its wet H2S cracking resistance. Whereas CE controls minimize the probability that weld heataffected zones will contain hard spots, residual welding stresses are not reduced whatsoever by CE controls. There is a widespread belief that postweld heat treatment is often not practical on finished carbon steel valve bodies. Whereas this may be true in specific cases, postweld heat treatment is actually performed on a routine basis on finished carbon steel bodies with excellent success. Prior heat history of the body castings usually results in a low enough stress state that distortion beyond design drawing tolerances does not occur. The table to the left briefly summarizes the major advantages and disadvantages of the three approaches.

Summary Carbon steel valves are commonly used in oil and gas production and refinery applications where they must be resistant to cracking in environments containing water and H2S. There are several industry standards and documents available that contain requirements and/or recommendations for welding of carbon steels destined for sour service, including NACE MR0175, NACE RP0472, and NACE Committee Report 8X194. The requirements listed in NACE MR0175 for carbon steels welded without subsequent PWHT are not very specific. NACE RP0472, in conjunction with Committee Report 8X194, documents several methods that can be used to ensure carbon steel weldments will be soft enough to resist cracking

in wet H2S environments. Those methods include hardness testing of weld deposits, postweld heat treatment, control of base metal CE to levels low enough to ensure low HAZ hardness, and weld procedure qualification hardness testing in conjunction with control of CE to intermediate levels and detailed welding process controls to ensure low HAZ hardness.

Conclusions Each of the hardness control methods has advantages and disadvantages. The selection of the most robust and economically attractive method depends upon several factors, including the available equipment, available welding procedure specifications, product forms (castings, plate, pipe, forgings, etc), and availability of heat treating equipment. In the case of valves, postweld heat treatment is an attractive method for preventing hard spots in weldments. It provides the secondary benefit of reducing residual stresses which can contribute to wet H2S cracking. Low CE requirements are an effective method for preventing hard spots in welds. However, low CE requirements increase raw material costs and lead time significantly, and have no beneficial effect on residual stresses generated by welding. Weld procedure qualification hardness testing, utilized in conjunction with intermediate CE requirements and restrictive welding process controls, does not appear to be a generally effective solution. Based upon the cost and lead time factors and the very restrictive welding process control requirements, this approach would probably be optimum only in very specific situations. If not for the cost and lead time issues surrounding the low CE control method, this approach would obviously be very popular and effective. A possible solution to this dilemma would be the development of ASTM standard carbon steel materials with a low carbon equivalent value (such as 0.43 maximum) as a requirement. For example, if a grade “WCD” were added to ASTM A216 (and ASME SA216) with this maximum CE requirement, and if valve companies were to adopt this new material their “standard” valve body material, it would eventually be no more expensive than a standard carbon steel body today. VM T he author is a Senior Engineering Specialist in the Materials Engineering Group at Fisher Controls International, Inc., Marshalltown, IA; 515.754.3011; www.froc.com.

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Footnotes 1

NACE Standard MR0175-2000, “Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment”, NACE International, Houston, TX, 2000. 2

NACE Standard RP0472-1995, “Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments”, NACE International, Houston, TX, 1995. 3

Shargay, C., “Overview of NACE International Standard RP0472”, Paper No. 417, NACE Corrosion/ 99, NACE International, Houston TX, 1999. 4

NACE Technical Committee Report 8X194, “Materials and Fabrication Practices for New Pressure Vessels Used in Wet H2S Refinery Service”, NACE International, Houston, TX, 1994.

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Rosafendi/ Charlie Chong

a permanent .

Rosafendi/ Charlie Chong