Australian Stainless #66 by Australian Stainless Steel Development Association

AUSTRALIAN STAINLESS Specialising in stainless steel and its applications

Photo credit: A&G Engineering

ISSUE 66 2019

FEATURE

Stainless for winemaking success A growing demand for quality wines in China has seen its third-largest winemaker venture onto Australian soil with a new state-of-the-art winery incorporating over 800t of stainless steel. Weilong Wines’ winery in Red Cliffs, Northern Victoria is the first Australian winery development of its magnitude for many years, and the company’s investment in the Murray-Darling region is a testament to the strong reputation and quality of Australian wine. Grape crushing for the export-only wine has already commenced following the completion of the winery’s construction in March 2019 and is expected to have wine bottled before the year-end in time for the Chinese New Year celebration in January 2020. ASSDA Member and Accredited Fabricator A&G Engineering designed, manufactured, delivered and installed all stainless steel storage and processing vessels for the new winery. The project scope was to achieve a vintage intake of over 26,000t capacity of grapes, equating to 21 million litres of wine.

Stainless steel was selected as the material of choice for the wine production equipment because of its excellent corrosion resistant properties, durability and ease-of-cleaning. Furthermore, the use of stainless steel does not impart additional flavour to the wine, preserving the original palates offered in the grape. A total of 180 stainless steel tanks in grade 304/304L were delivered - 124 storage vessels ranging from 30kL to 1200kL, 42 fermentation vessels and 14 general processing tanks - plus associated stair towers, platforms, catwalks, support structures and connections. Over 700t of 2mm-6mm stainless steel coil was supplied for the project by ASSDA Member, Outokumpu. In addition, the A&G Stainless Steel Sales Department was engaged to supply over 15km of primarily 304 grade tube in sizes ranging from 20mm to 300mm, plus all associated fittings.

Two 1200kL storage vessels were manufactured by A&G on site, using their own fully automated Plasma TIG welding process for tank manufacture, Site PAM (Precision Automated Manufacturing). The unique system was designed with a focus on large-capacity stainless steel vessels being constructed in the field, giving A&G the capability to custom build vessels that hold in excess of 5 million litres. Site PAM’s automatic planishing system compresses the weld with high pressure to ensure there are no peaks inside or outside of the tank, providing an aesthetically pleasing finish and a flat surface for the automated polishing application. All vessels were passivated for added corrosion resistance.

Photo credit: A&G Engineering

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technologically-advanced, modern winery with state-of-the-art stainless steel equipment...built to last

Photo credit: A&G Engineering

With safety and logistical considerations managed, 24-hour shifts were undertaken to fabricate the two 1200kL tanks to minimise downtime and maximise the efficiency of the project planners and estimators’ time on site. The fabrication of the remaining 178 stainless steel storage vessels were spread across A&G’s three workshop premises, including Griffith in New South Wales, Mildura in Victoria and Angaston in South Australia. The extensive logistical challenges were managed with diligent project management, forward planning and transparency across the three sites and different production teams. Transportation of the larger storage vessels required National Heavy Vehicle

Regulator road permits, allowing only small pre-set time windows and significant planning to ensure loading and unloading occurred as planned to meet the scope of the permit. All vessels were delivered on A&G’s specialised tank trailers, and the larger vessels were transported on trailers specifically designed for the operation to comply with road regulations and permit requirements. A&G was also appointed as the WH&S Principal Contractor for its portion of the works, taking responsibility and liability for all safety aspects on those parts of the site under its control. With the complexity of works being undertaken day-to-day, including the use of cranes up to 100t, heavy materials, working at heights, hot

works, traffic management, job safety analysis requirements and standard operating procedures, the breadth of safety considerations were significant. Zero injuries or notifiable incidents were recorded over the duration of the tenmonth project on site, a fantastic result given the magnitude of the project. The end result is a technologicallyadvanced, modern winery with stateof-the-art stainless steel equipment and infrastructure built to last. With China continuing to drive growth and demand for wine imported from Australia, Weilong Wines plan to expand production each year, with the potential for future capacity to reach 168,000t per annum.

ASSDA MEMBER CONTACTS A&G Engineering \ Randall Collins, Business Development Manager \ +61 2 6964 3422 \ rcollins@agengineering.com.au \ agengineering.com.au Outokumpu \ George Miech, Business Development & Sales Manager – Australia & New Zealand \ +61 419 698 773 \ \ george.miech@outokumpu.com \ outokumpu.com

3 – Australian Stainless Issue 66

TECHNICAL

Shielding gases for welding AND THEIR EFFECTS ON STAINLESS STEEL PROPERTIES

Shielding gases form an integral part of all conventional welding processes. They serve multiple functions but are primarily there to shield the weld pool from the atmosphere and to provide a medium which can allow the flow of electricity from an electrode to a workpiece. Even processes that do not have an external gas supply such as Manual Metal Arc Welding (MMAW or MMA or SMAW) and Gasless Flux-cored Arc Welding (FCAW) all have a shielding gas which is generated by the decomposition of the flux in the presence of the welding arc. The shielding gas can also have an effect on arc stability, weld shape and depth of penetration as well as the mechanical properties and metallurgy of stainless steel weldments. The gas shielded processes such as Gas Tungsten Arc Welding (GTAW or TIG) and Gas Metal Arc Welding (GMAW or MIG) use shielding gases of a variety of compositions depending on the application. As the electrode in GTAW is made of tungsten, the shielding gas is typically argon or helium to prevent oxidation of the electrode. This restriction does not apply to GMAW and therefore the gas composition may include active gases such as carbon dioxide and oxygen. Small quantities of other gases such as nitrogen and hydrogen can be utilised with both of these processes as they are particularly advantageous for the welding of stainless steel. While neither gas is inert by definition, they can be used with GTAW as neither react with tungsten. There are three key properties of the shielding gas which control the way the weld pool behaves; the ionisation potential (how easily an atom will give up an electron), the thermal conductivity of the gas, and finally the surface tension between the weld pool and the shielding gas.

Ionisation potential

Thermal conductivity

The shielding gas allows transfer of electrons between the electrode and the workpiece. Upon arc initiation, electrons are emitted from either the workpiece or the electrode depending on which is positively charged. These electrons collide with gaseous atoms which results in these atoms liberating one of their electrons which results in a chain reaction that sustains the arc. The ionisation potential of the gas is the ease with which they will give up an electron. ‘Hotter’ gases are those which require more energy to ionise or release an electron. Helium has a higher ionisation potential than argon, so has a higher arc voltage and hence a higher heat input for the same current and arc length. A similar principle applies to molecular gases (H2, N2, O2, CO2) which dissociate in the arc into individual atoms and then recombine upon cooling, releasing energy in the process. Argon is often mixed with small amounts of other gases to improve weld penetration.

The thermal conductivity of a shielding gas affects its ability to transfer heat across the arc. It influences the radial heat loss from the centre to the periphery of the arc column as well as heat transfer from the arc to the molten weld pool. Gases with low thermal conductivity such as argon will tend to have a narrow hot core in the centre of the arc and a considerably cooler outer zone. The result is a weld with a narrow ‘finger’ at the root of the weld and a wider top. On the other hand, helium has a high thermal conductivity, so heat is more evenly distributed across the arc, but as a result the depth of penetration is lower. Mixing gases allows combination of the advantageous properties of each gas while limiting the drawbacks.

Ar-He

CO2

Figure 1: Influence on shielding gas properties on penetration profile. (Credit: TWI Ltd) 4 – Australian Stainless Issue 66

Surface tension Surface tension affects the bead profile of a weld. Picture how water beads up on a newly polished car. This is undesirable in welding as it creates a steep angle between the weld and the parent which could lead to defects such as undercut, lack of sidewall fusion and decreased fatigue performance. This is another reason why pure argon is not used as a shielding gas for the GMAW process.

Gas components Oxygen

Carbon Dioxide

Hydrogen

Nitrogen

Though seemingly counterintuitive as it is well known that hot metals oxidise, small amounts of oxygen are often added to shielding gasses for the GMAW process. Small amounts of oxygen reduce the surface tension between the molten weld pool and the surrounding atmosphere. Lower surface energy results in a flatter and smoother weld bead with less tendency to undercut the parent metal. To minimise alloy losses by oxidation, oxygen content is typically limited to 2%. The heat tint will be more severe than for a weld without oxygen additions to the shielding gas.

GMAW also utilises CO2 as a constituent of the shielding gas. A common concern with stainless steels is embrittlement and corrosion through sensitisation due to chromium carbide formation, but the carbon pickup from CO2 has been demonstrated to be low enough that the resultant weld metal still achieves the required (< _ 0.03%) carbon content for L grade designation. The chosen CO2 content is therefore more about penetration and wetting than it is about carbon pick-up. Carbon dioxide contents in GMAW are typically 2-5% while flux-cored wires utilise 20% mixtures with argon or even 100% CO2.

Unique to austenitic stainless steels is its immunity to hydrogen cracking – except possibly in very heavily cold-worked material. This allows the addition of hydrogen to the shielding gas in quantities from 2–15% providing more heat in the arc and better penetration. Hydrogen quantity for manual welding is usually restricted to 5%, with the higher concentrations limited to automated process such as orbital GTAW. Hydrogen cannot be used as a component of the shielding gas for ferritic, martensitic or duplex stainless steels due to a risk of cracking.

Nitrogen is a useful shielding gas additive for duplex stainless steels which contain dissolved nitrogen. It is added to increase pitting resistance and in acting as an austenite stabiliser to create a balanced ‘duplex’ microstructure in the weld, especially for thin materials which cool too rapidly to allow sufficient austenite to form. Nitrogen can be added to both the welding gas and the purge gas to prevent the loss of nitrogen during welding.

This article has dealt with gases for the active side of a weld. When welding tube or pipe, it is normal to feed an inert gas such as argon or nitrogen into the tube or pipe to maintain low oxygen levels and minimise heat tint formation to no more than pale straw. This usually requires a sensitive oxygen meter or possibly previously proven purging practices. In thick sections, purging must continue for all passes. Nitrogen purging of duplex root passes will improve the corrosion resistance but may also upset the phase balance. Hydrogen additions have been used in purge gases for both austenitic and duplex welds to minimise heat tints.

This article was written by Matthew Cole, International Welding Engineer and Metallurgist at GMC Welding Consultants.

GMC Welding Consultants provides welding engineering, management and inspection services to construction, pressure equipment, pipeline and associated industries. With vast experience and expert knowledge we are able to deliver comprehensive quality management of the welding process on behalf of our clients whilst acting as their representative. 0427 018 608 \ matthew.cole@gmcconsultants.com.au \ gmcconsultants.com.au

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DESIGN

Coastal living STAINLESS STEEL POOL FENCING Safety is the number one consideration when building a pool fence, and stainless steel delivers in compliance and material strength while fulfilling design and aesthetic needs. A stunning canal-front home on the Gold Coast features a streamlined stainless steel vertical balustrade system as supplied by ASSDA Member Miami Stainless.

Grade 316 stainless steel was specified for its aesthetic appeal, material strength and corrosion resistance, particularly with the homeâ&#x20AC;&#x2122;s waterfront location and close proximity to the coastline.

The custom-designed stainless steel pool fence features 50mm square mirrorpolished posts and upper and lower rails. Complying with Queensland pool fencing and safety barrier regulations, the vertical stainless steel wire balustrades were spaced 80mm apart and installed using Miami Stainlessâ&#x20AC;&#x2122; Nutsert Swage Stud System on the base with a ProRig Flip Toggle into the handrail.

In addition, stainless steel is a durable and long-lasting alternative to aluminium balustrades and offers reduced household maintenance when compared with glass. Glass fencing often requires frequent cleaning to remove chlorine or saltwater splashes and finger marks.

The stainless steel pool fence ticks all the boxes in combining safety, unobstructed views, durability, minimal maintenance and luxury style.

Grade 316 stainless steel was specified for its aesthetic appeal, material strength and corrosion resistance...

Photo credit: Miami Stainless

ASSDA MEMBER CONTACTS Miami Stainless \ Stuart Harris, Sales Manager \ 1800 022 122 \ info@miamistainless.com.au \ miamistainless.com.au

DESIGN

IMMERSE YOURSELF IN

Stainless luxury Setting the benchmark in boutique luxury and innovation using stainless steel is Brisbane’s Emporium Hotel. Developed by the Anthony John Group, The Emporium Hotel opened in July 2018. Nestled in the premier lifestyle and cultural precinct of South Bank, the 143-suite hotel is turning heads with its exquisite interior design, bespoke handcrafted features and luxurious facilities. Stainless steel was the material of choice for the five-star hotel and selected for its quality, opulent aesthetic and luxury appeal. Over 5.5 tonnes of grade 304 stainless steel sheet, 1.2mm thick in a No. 8 mirror finish was used throughout the five-star hotel and supplied by ASSDA Member Fagersta Steels. ASSDA Member and Accredited Fabricator, Langford Metal Industries, was engaged to laser cut the mirror finish material to bring the developer’s trademark design to life, which was installed by Thump Architectural. The frangipani inspired pattern represents the Queensland theme and character, and the laser cut stainless steel prevails throughout the hotel on mullions, sliding doors, external panels, columns, cabana suites surrounding the 23m infinity edge pool – almost anywhere and everywhere, serving both a functional and decorative purpose.

A remarkable feature of the hotel is its rooftop bar on the 21st floor, The Terrace. Presenting panoramic views of South Bank Parklands, the Brisbane River and the city skyline, The Terrace maximises the warm Queensland weather with two retractable roofs offering full, partial or no exposure. Measuring 7.5m long, 2.1m wide and 50mm thick, the ceiling of the first retractable roof features the impressive frangipani stainless steel design. The sliding panel is a composite structure incorporating insulation and structural members which are clad top and bottom with mirror polished stainless sheet. For structural purposes, the panel was shaped into a shallow moon profile to form the roof’s arch. When retracted, a second roof made of glass is revealed, which is also retractable for a complete outdoor rooftop experience. The stainless steel ceiling and surrounding elements complement the rooftop bar’s sub-tropical luxe vibe with ceiling-to-floor glass doors, lush greenery, and white backlit onyx floor tiles and bar. Photo credit: Emporium Hotel

ASSDA MEMBER CONTACTS Fagersta Steels \ Rob Robbins, QLD Branch Manager \ +61 7 3863 1300 \ qldsales@fagersta.com.au \ fagersta.com.au Langford Metal Industries \ Glen O’Shanesy \ +61 7 3606 9000 \ glen@langfordmetal.com.au \ langfordmetal.com.au

2019 ► Showcase products & services ► Promote global B2B ventures ► Strengthen existing relationships ► Initiate new partnerships

► Three day conference ► Application orientated

For more information:

► International Steering Committee ► Knowledge exchange

Stainless Steel World

.YEARS.

KCI Publishing Celebrates .1989 - 2019 .

Conference & Expo

26th - 28th November 2019 Maastricht, The Netherlands

► Meet more than 300 exhibitors ► Join over 6000 visitors

► Latest global market trends ► Material developments

► Exhibition Sales Manager: Mrs Elisa Hannan Email: e.hannan@kci-world.com Tel: +31 575 585 291

► Network with your peers ► Reach decision makers

► Technological innovations ► Future industry strategies

►Conference Manager: Mr John Butterfield Email: j.butterfield@kci-world.com Tel: +31 575 585 294

Australian Stainless #66

Articles inside

Stainless for winemaking success

Shielding gases for welding and their effects on stainless steel properties

Immerse yourself in stainless luxury

Coastal living: Stainless steel pool fencing