Api570 chapter 6

Sec~6 6 Interval/Frequency and Extent of Inspection 检验间隔时间/频率和程度

6 Interval / Frequency and Extent of Inspection 检验间隔时间/频率和程度 6.1 General 概要 6.2 Inspection During Installation and Service Changes 检查在安装和服务过程中的变化 6.3 Piping Inspection Planning 管道检测规划 6.4 Extent of Visual External and CUI Inspections 外观与CUI 查程度 6.5 Extent of Thickness Measurement Inspection 厚度测量检验程度 6.6 Extent of Small-bore, Auxiliary Piping, and Threaded-connections Inspection 小口径,辅助管道和螺纹连接的检查程度 6.7 Inspection and Maintenance of Pressure-relieving Devices (PRD) 泄压装置的检查和维护

6.1 General 大纲

6.1 General 大纲 意图: API 570 是根据监察代表性的抽样选定管道检验点; 刻意,带意图,合理,准确的评 估管道的状况以确保设备的完整性. 检验间隔: 所有的管路系统和泄压装置应按照本节中提供的时间间隔/频率检查.在到期日 或之前应进行定期检查或被视为“逾期检查”. 根据API 580风险评估的结果,这时 间间隔可延长检验日期,在这期限结束之前不视为“逾期检查” 目的: 设备检验后,应当能提供足够的信息以确定所有设备的重要部分或组件是安全的, 直到下一次的定期检查工作. 内部检验负面影响: 计划进行内部检查时,应当对设备关机和启动带来的增加腐蚀的可能性(启动/关 机过程中对空气和水接触等) 进行评估.

设备关机和启动带来的内壁增加腐蚀 (启动/关机过程中对空气和水接触等)

6.2 Inspection During Installation and Service Changes 安装和服务的变化过程中的检验

6.2.1 Piping Installation 管道施工 在管道施工安装时,管道应按照施工要求的规范 (ASME B31.3) 检查. 安装检查应包括以下项目: 1. 验证管道是否正确安,管托/支撑/附属结构件等正确安装, 保温层正确安装, 法兰和其他机械连接正确组装管, 道清洁和干燥; 2. 验证泄压装置满足设计要求和正确安装 在改造管线施工,创建一个准确的腐蚀速率计算基础点 CML/TML: 舍弃规格标称和最小厚度数据, 记录实际管线壁厚作为厚度基线用来作为初 始厚度的厚度测量腐蚀速率计算.

6.2.2 Piping Service Change 管道服务变化 如果管道系统的 (1) 服务条件改变 (工艺参数例如容液变化,最大工作压力, 最高 和最低工作温度) ,新的检查间隔时间应重新建立, 符合服务条件的更改. 如果管道 (2) 所有权和管道的 (3) 位置有所改变时,设备在重新使用之前,应检查 服务条件(工艺参数)是否有所变动.检查间隔应依照需求重新建立.

6.3 Piping Inspection Planning 管道检测规划

6.3.1 General 大纲 管道系统上进行检查的频率和程度取决于：  损坏机理(表-1)  发生故障可能会影响的结果 API 571对各种形式影响工艺管道更详细地描述.

Section 6.3.4 中定义基于故障的后果的管道的简化的分类,用于建立检的频率和程度. 业主/用户可能会制定一个更广泛的分类方案更准确的评估某些管道系统故障的后果. 后果评估考虑潜在的 (1) 爆炸 (2) 火灾 (3) 中毒 (4) 对环境的影响 (5) 其他相关的潜 在影响失效的后果.

RBI 基于风险分析检验-是基于(1) 故障概率检和 (2) 失败的后果验策略

在一个有效的评价的结果可以被用来建立一个管道检验策略和定义如下：    

利用相应的检验方法,范围,工具和技术的基础上的预期损伤机理 相应的检验频率 压力测试要求-修理, 修改,损坏后复位. 减少管道发生故障的概率和后果的预防和减缓行动

6.3.2 RBI for Inspection Planning 运用RBI作为检验计划因素 An RBI assessment may be used to increase or decrease the inspection limits described in Table 2. Similarly, the extent of inspection may be increased or decreased beyond the targets in Table 3, by an RBI assessment.

When used to increase inspection interval limits or the extent of inspection, RBI assessments shall be conducted at intervals not to exceed the respective limits in Table 2, or more often if warranted by process, equipment, or consequence changes. These RBI assessments shall be reviewed and approved by a piping engineer and authorized piping inspector at intervals not to exceed the respective limits in Table 2, or more often if warranted by process, equipment or consequence changes.

RBI 可以被用来增加或减少表2中所述的检验限制, RBI评估应当在不超过表2中的各自的限制间隔内执行或如果必要因工艺,设备, 或后果变化在更短的时间,重估.

RBI 基于风险分析检验-是基于 (1) 故障概率检和 (2) 故障后果 验验策略

6.3.3 Inspection Intervals 检验时间间隔 如果RBI不启用的情况： 检验时间间隔不超过(最小值) :  法定要求  从腐蚀速率确定一半厚度测量的剩余寿命  表-2允许的最大时间隔. 在有必要时适当的调整检验时间隔,考虑范围有: 腐蚀机理, 生产与工艺条件, 以前的检查历史,当前检查结果.

6.3.4 Piping Service Classes 管道级别 6.3.4.1 General 总则 基于发生泄漏潜在的安全和环境影响, 所有工艺管道系统分为不同的管道 分类. 这样的分类系统允许额外的检查力度, 重点在较高的分类系统需要在 更短的间隔,更广泛的检查以确认其完整性-持续安全运行. 小编: 上述考虑项为: “基于发生泄漏潜在的安全和环境影响” – RBI里的故障模式 (failure scenario)项的一小节, 故障概率(probability)这里没有描述.

Damage mechanism → failure mode → failure Scenario → Consequence

小编: 上述考虑项为: “基于发生泄漏潜在的安全和环境影响” – 受压”溶液特征”是影响RBI COF里的故 障模式(failure scenario)项的一小节, 故障概率(probability) 这里没有描述. 例如:失效概率很低的 一类管系检验间隔和失效概率很高的一类管系是一样的. 失效情景一般上; Damage mechanism (广义腐蚀) → failure mode (蚀孔)→ failure Scenario (小量泄漏x溶液特征) → Consequence (后果其一:局部火灾)

所有工艺管系系统应 分为不同的检验分类; Class 1,2,3,4 + +

所有工艺管道系统应分为 不同的管道分类 +,+

管道分类: S/A , CUI, +++

6.3.4.2 Class 1 Services with the highest potential of resulting in an immediate emergency if a leak were to occur are in Class 1. Such an emergency may be safety or environmental in nature.

Class 1 如果泄漏发生, 最有潜力导致即时的的安全或环境本质上紧急状况.

Class 1 如果泄漏发生，最有潜力导致即时的的安全或环境本质上紧急: 考虑条件 (a, b, c) 服务因素: 易燃服务,迅速蒸发加压服务,脆性断裂, 3%硫化氢硫化氢,无水氯化氢,氢氟 酸

+ plus

温度因素: 自燃温度,常压沸点温度, 操作温度高于沸点温,释放时自冷低于延脆转变温 度

+ plus

国家法规环境要求(美国运输和美国海岸卫队法规）

1. Flammable services that can auto-refrigerate and lead to brittle fracture. 易燃服务: 释放时自冷(低于延脆转变温度),并导致脆性断裂, 2. Pressurized services that can rapidly vaporize during release, creating vapors that can collect and form an explosive mixture, such as C2, C3, and C4 streams.

Fluids that can rapidly vaporize are those with atmospheric boiling temperatures o o below 50 F (10 C) or where the atmospheric boiling point is below the operating temperature (typically a concern with high-temperature services). 加压服务: 在释放过程中迅速蒸发,形成或集合为爆炸性混合物与常压沸点温度低 o o 于50 F(10 C)或 低于操作温度(高温系统), 3. Hydrogen sulfide (greater than 3% weight) in a gaseous stream.

3%硫化氢硫化氢, 4. Anhydrous hydrogen chloride 无水氯化氢, 5. Hydrofluoric acid 氢氟酸, 6. Piping over or adjacent to water and piping over public throughways (refer to Department of Transportation and U.S. Coast Guard regulations for inspection of over water piping). 相邻公共水资源和公共通道上的管路, 7. Flammable services operating above their auto-ignition temperature. 易燃服务: 工作温度高于其自燃温度.

6.3.4.3 Class 2 二类管系 Services not included in other classes are in Class 2. This classification includes the majority of unit process piping and selected off-site piping.

Typical examples of these services include but are not necessarily limited to those containing the following: a) on-site hydrocarbons that will slowly vaporize during release such as those operating below the flash point, 内场低于闪点服务;在释放过程中慢慢蒸发 b) hydrogen, fuel gas, and natural gas, 氢,燃料气体,天然气, c) on-site strong acids and caustics. 场区内强酸和碱液. 二类基本上包括大多数的场内,与小部分的场外工艺管系. 那些不归于在其他类别管系(1,3,4)的是归于第2类管系.

Class 2: 此分类包括大多数的处理单元工艺管道和一些场外管道.

6.3.4.4 Class 3 Services that are flammable but do not significantly vaporize when they leak and are not located in high-activity areas are in Class 3. Services that are potentially harmful to human tissue but are located in remote areas may be included in this class.

Class 3

可燃物服务,在释放过程中不显着蒸发, 泄漏并非位于高活性区. 位于偏远地区对人体组织有潜在伤害的(蒸汽?,热水?,微害性小?)管系,也可 以归于三类服务.

Services that are potentially harmful to human tissue but are located in remote areas may be included in this class. (???)

1. on-site hydrocarbons that will not significantly vaporize during release such as those operating below the flash point; 低于闪点服务: 在释放过程中不会显着蒸发的厂区碳氢化合物, 2. distillate and product lines to and from storage and loading; 馏分物和产品,储存和装载管道, 3. tank farm piping; 罐区管道, 4. off-site acids and caustics. 场区外酸液碱溶液管道.

6.3.4.5 Class 4 / 4 类 Services that are “essentially nonflammable -基本上是不可燃的” and nontoxic are in Class 4, as are most utility services. Inspection of Class 4 piping is optional and usually based on reliability needs and business impacts as opposed to safety or environmental impact. Examples of Class 4 service include, but are not necessarily limited to those containing the following:

a) b) c) d) e) f) g)

steam and steam condensate; 蒸汽和蒸汽冷凝水 air; 空气 nitrogen; 氮气 water, including boiler feed water, stripped sour water; 水,包括;锅炉补给水,剥离酸水 lube oil, seal oil; 润滑油,密封油 plumbing and sewers: 生活共用管道和污水管道 ASME B31.3, Category D services; D类服务

Class 4 基本上都是不可燃，无毒的服务

Class 4

蒸汽和蒸汽冷凝水

润滑油, 密封油

ASME B31.3, Category D services

ASME B31.3 Category D Fluid Service: a fluid service in which all the following apply: 1. the fluid handled is nonflammable, nontoxic, and not damaging to human tissues as defined in para. 300.2 处理的流体是不易燃的,无毒的,不损害人体组织 2. the design gage pressure does not exceed 1035 kPa (150 psi) 设计不超过10公斤表压 3. the design temperature is from -29oC (-20oF) through 186oC (366oF) 设 计温度范围为-29oC ~ +186oC

6.4 Extent of Visual External & CUI Inspections 外观 & CUI 检查程度

http://www.ndt.net/article/wcndt00/papers/idn751/idn751.htm http://www.ndt.net/article/0298/twomey/twomey.htm

Guided Wave Ultrasonic Testing (GWUT) http://www.tmqc.com.tw/motion.asp?siteid=1002958&menuid=17737&postid=16895 &csw=1

External visual inspections, including inspections for CUI, should be conducted at maximum intervals listed in Table 2 to evaluate items such as those in API 574. Alternatively, external visual inspection intervals can be established by using a valid RBI assessment conducted in accordance with API 580.

应当在表2中列出的最大间隔,或者可以通过使用有效的 RBI 建立间隔

Corrosion under insulation 保温层下的腐蚀

API574, 7.4.4.1 Insulated Piping Systems Susceptible to CUI 易受影响管道系统

7.4.4 CUI External inspection of insulated piping systems should include a review of the insulation system integrity for conditions that could lead to CUI and signs of ongoing CUI. API 570 documents the requirements of a CUI inspection program. Sources of moisture can include rain, water leaks, condensation, deluge systems, and cooling towers. The two forms of CUI are localized corrosion of carbon steel and chloride SCC of austenitic stainless steels. See API 571 for additional details on CUI mechanisms. This section provides guidelines for identifying potential CUI areas for inspection. The extent of a CUI inspection program may vary depending on the local climate. Marine locations in warmer areas may require a very active program, whereas cooler, drier, mid-continent locations may not need as extensive a program.

7.4.4.1 Insulated Piping Systems Susceptible to CUI Certain areas of piping systems are potentially more susceptible to CUI, including: a) b) c) d) e)

f) g) h) i) j) k) l)

those exposed to mist over-spray from cooling water towers; those exposed to steam vents; those exposed to deluge systems; those subject to process spills or ingress of moisture or acid vapors; carbon steel piping systems, including ones insulated for personnel protection, operating between 10°F (–12°C) and 350°F (175°C); CUI is particularly aggressive where operating temperatures cause frequent or continuous condensation and reevaporation of atmospheric moisture; carbon steel piping systems which normally operate in service above 350°F (175°C), but are in intermittent service; dead-legs and attachments that protrude from insulated piping and operate at a different temperature than the operating temperature of the active line; austenitic stainless steel piping systems operating between 120°F (60°C) and 400°F (205°C) (susceptible to chloride SCC); vibrating piping systems that have a tendency to inflict damage to insulation jacketing providing a path for water ingress; steam traced piping systems that can experience tracing leaks, especially at tubing fittings beneath the insulation; piping systems with deteriorated insulation, coatings, and/or wrappings; bulges or staining of the insulation or jacketing system or missing bands (bulges can indicate corrosion product buildup); piping systems susceptible to physical damage of the coating or insulation, thereby, exposing the piping to the environment.

API RECOMMENDED PRACTICE 574 THIRD EDITION, NOVEMBER 2009

7.4.4.2 Typical Locations on Piping Circuits Susceptible to CUI The above noted areas of piping systems can have specific locations within them that are more susceptible to CUI. These areas include the following. a)

All penetrations or breaches in the insulation jacketing systems, such as:

— dead-legs (vents, drains, etc.); — pipe hangers and other supports; — valves and fittings (irregular insulation surfaces); — bolt-on pipe shoes; and — steam and electric tracer tubing penetrations. b) c) d) e) f) g) h)

Termination of insulation at flanges and other piping components.

Damaged or missing insulation jacketing.

Insulation jacketing seams located on the top of horizontal piping or improperly lapped or sealed insulation jacketing.

Termination of insulation in a vertical pipe.

Caulking which has hardened, separated, or is missing.

Low points in piping systems that have a known breach in the insulation system, including low points in long unsupported piping runs.

Carbon or low-alloy steel flanges, bolting, and other components under insulation in high-alloy piping systems.

Particular attention should be given to locations where insulation plugs have been removed to permit piping thickness measurements on insulated piping. These plugs should be promptly replaced and sealed. Several types of removable plugs are commercially available that permit inspection and identification of inspection points for future reference.

API RECOMMENDED PRACTICE 574 THIRD EDITION, NOVEMBER 2009

API574, 7.4.4.1 Insulated Piping Systems Susceptible to CUI 易受影响管道系统 以下为易受保温层腐蚀的管道系统: 1. those exposed to mist over-spray from cooling water towers; 那些接触过喷雾冷却水塔 2. those exposed to steam vents; 那些暴露在蒸汽喷口 3. those exposed to deluge systems; 那些暴露在雨淋系统 4. those subject to process spills or ingress of moisture or acid vapors; 易被工艺媒介溢出或酸性气体/水分渗入 5. carbon steel piping systems, including ones insulated for personnel protection, operating between 10o F (–12oC) and 350oF (175oC); CUI is particularly aggressive where operating temperatures cause frequent or continuous condensation and re-evaporation of atmospheric moisture; 工作温度波动易引起连续凝结和蒸发大气中的水分的工艺管路

API RECOMMENDED PRACTICE 574 THIRD EDITION, NOVEMBER 2009

6. carbon steel piping systems which normally operate in service above 350oF (175oC), but are in intermittent service; 在高温工作的但间歇服务(这会引起重 复的凝结与蒸发-导致一般腐蚀与环境开裂) 7. dead-legs and attachments that protrude from insulated piping and operate at a different temperature than the operating temperature of the active line; 死角和附件绝缘管道伸出，并在不同的温度下运作 8. austenitic stainless steel piping systems operating between 120oF (60oC) and 400oF (205oC) (susceptible to chloride SCC);奥氏体不锈钢管道系统在以上温度波动 工作,引起重复的凝结与蒸发-导致环境开裂 9. vibrating piping systems that have a tendency to inflict damage to insulation jacketing providing a path for water ingress; 震动管道(引起保温层破坏) 10. steam traced piping systems that can experience tracing leaks, especially at tubing fittings beneath the insulation; 带蒸汽伴管管道-可能泄露导致保温层潮湿 11. piping systems with deteriorated insulation, coatings, and/or wrappings; bulges or staining of the insulation or jacketing system or missing bands (bulges can indicate corrosion product buildup);管道系统的涂层,保温层,缠绕带劣化的管道 12. piping systems susceptible to physical damage of the coating or insulation, thereby, exposing the piping to the environment. 容易受到物理伤害管道系统 API RECOMMENDED PRACTICE 574 THIRD EDITION, NOVEMBER 2009

API 574 7.4.4.1-表示易受保温层下的腐蚀温度范围 1. 碳钢管道系统(包括人员保护绝缘): 频繁服务温度波动管系 10°F ~ 350°F (-12°C~175 °C) CUI 活跃/积极波动服务温度.因这工作温度 段会导致频繁或连续大气中的水分冷凝/蒸发和再冷凝循环.

2. 碳钢通常服务超过 350°F (175°C ), 但在间歇服务.

3. 奥氏体不锈钢管道系统120°F~400°F( 60°C~ 205°C) 之间 (SCC 应力腐蚀开裂)

API RECOMMENDED PRACTICE 574 THIRD EDITION, NOVEMBER 2009

API 574 7.4.4.1-表示易受保温层下的 腐蚀温度范围 1. 碳钢管道系统(包括人员保护绝 缘): 频繁服务温度波动管系 10°F ~ 350°F (-12°C~175 °C) 2. 碳钢通常服务超过 350°F (175°C ), 但在间歇服务.

3. 奥氏体不锈钢管道系统 120°F~400°F( 60°C~ 205°C) 之间 (SCC 应力腐蚀开裂)

API 574 7.4.4.1-表示易受保温层下的腐蚀温度范围  铁素体/碳钢/低合金钢点状腐蚀  奥氏体不锈钢管道系统应力腐蚀开裂

铁素体/碳钢/低合金钢点状腐蚀

铁素体/碳钢/低合金钢点状腐蚀

铁素体/碳钢/低合金钢点状腐蚀

铁素体/碳钢/低合金钢点状腐蚀

铁素体/碳钢/低合金钢点状腐蚀

Piping systems that are known to have a remaining life of over 10 years or that are adequately protected against external corrosion need not be included for the NDE inspection recommended in Table 3. However, the condition of the insulating system or the outer jacketing, such as a cold-box shell, should be observed periodically by operating or other personnel. If deterioration is noted, it should be reported to the inspector. The following are examples of these systems: 已知有剩余年期为10年以上,或得到充分保护免受外部腐蚀的管道系统可以不 需要按照表-3所建议进行无损探伤 NDE检验.然而, 操作员或其相关人员应当经 常检查保温系统,保温层外护套.任何的衰败应当及时通知授权检验员

上述说的不受 CUI 影响的工艺管线例子有; 1. piping systems insulated effectively to preclude the entrance of moisture,有效地阻止水分渗入的绝缘管道系统 2. jacketed cryogenic piping systems,冷冻低温管道系统 3. piping systems installed in a cold box in which the atmosphere is purged with an inert gas, 用惰性气体吹扫绝缘护套的管道系统 4. piping systems in which the temperature being maintained is sufficiently low or sufficiently high to preclude the presence of water. 温度保持足够低或足够高以阻止液态水的存在管道系统

充分保护免受外部腐蚀的管道系统

23) Certain areas and types of piping systems are potentially more susceptible to corrosion under insulation. Which of the items listed is not susceptible to CUI? a) Areas exposed to mist over-spray from cooling water towers. b) Carbon steel piping systems that normally operate in-service above 250 degrees but are in intermittent service. c) Deadlegs and attachments that protrude from insulated piping and operate at a different temperature than the temperature of the active line. d) Carbon steel piping systems, operating between 250 degrees F and 600 degrees F. 22) What climatic area may require a very active program for corrosion under insulation? a) b) c) d)

Cooler northern continent locations.

Cooler direr, mid-continent locations Warmer, marine locations Warmer drier, desert locations

21) What are the most common forms of corrosion under insulation (CUI). a) Localised corrosion of non-ferrous metals and chloride stress corrosion cracking of carbon steel. b) Localised corrosion of chrome-moly steel and chloride stress corrosion cracking of ferritic stainless steel. c) Localised corrosion of carbon steel and chloride stress corrosion cracking of austenitic stainless steel d) Localised corrosion of nickel-silicon alloy and caustic stress corrosion of austenitic stainless steel 24) What location is subject to corrosion under insulation and inspection contributes to it? a) Locations where pipe hangers and other supports exist. b) Locations where insulator has been stripped to permit inspection of the piping. c) Locations where insulation plugs have been removed to permit piping thickness measurements. d) Locations where there is damaged or missing insulation jacketing.

6.5 Extent of Thickness Measurement Inspection 厚度测量检验范围

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厚度测量检查应获得足够有代表性的TML采样厚度读数, 应包括所有不同组件和 方向(水平和垂直)数据.有效的厚度测量有助于策划将来的检验间隔与范围

6.6 Extent of Small-bore, Auxiliary Piping, and Threaded-connections Inspections. 小口径, 辅助管道, 螺纹 连接检查范围

6.6.1 SBP Inspection 小口径检查范围 小口径主要工艺管道 主要工艺管道应按照本文件(同等主要工艺大管线) 要求的检查. 小口径次要工艺管道 次要工艺管道有不同的最低要求，这取决于服务分类:  一类应按照主要工艺管道相同的要求检查。  二/三类为可选性。  经历或预期有潜在腐蚀的死角(列如:液位抑制器)应该策划检查.

API570, 3.1.72 primary process piping 主要管线 Process piping in normal, active service that cannot be valved off or, if it were valved off, would significantly affect unit operability. Primary process piping normally includes most process piping greater than NPS 2, and typically does not include small bore or auxiliary process piping (see also secondary process piping). 工艺管道正常,主流服务, 不能关闭阀或, 如果它被关闭阀，将显着影响单元可 操作性。一般大于2寸口径管道。通常不包括小口径或辅助工艺管道

API570, 3.1.85 secondary process piping 次要管线 Process piping, often SBP downstream of block valves that can be closed without significantly affecting the process unit operability. 工艺管线通常为小口径管线,如隔断阀的下游,可以关闭而不会显着影响该单 元过程的生产可操作性

Deadlegs with CMLs should be tracked in a separate piping circuit from the mainline piping. These deadlegs or low points are typically identified and documented in the inspection record by the inspector. Deadlegs may be combined into one circuit if their anticipated corrosion rates are similar.

Inspections should include profile radiography on small diameter deadlegs, such as vents and drains, and UT or RT on larger diameter deadlegs. 死角应当作为独立于主流管线跟踪, 如果他们预期的腐蚀速率是相似的,死角可以 组合成一个同一检验单元. 厚度测量探伤法有:  小口径管路可能需要剖面射线法,  大口径管路使用超声或射线探伤法.

6.6.2 Auxiliary Piping Inspection 辅助管道检验 Inspection of auxiliary SBP associated with instruments and machinery is optional and the need for which would typically be determined by risk assessment. Criteria to consider in determining whether auxiliary SBP will need some form of inspection include the following: 仪器及机械相关的辅助小口径管线检查是可选的, 如有需要检验,通常是通过 风险评估来确定,考虑确定标准有： 1. classification,分类 2. potential for environmental or fatigue cracking, 潜在的环境或疲劳开裂 3. potential for corrosion based on experience with adjacent primary systems, 与相邻的主系统经验的基础上考虑潜在的腐蚀性, 4. potential for CUI. 保温层腐蚀

6.6.3 Threaded-connections Inspection 螺纹连接检验 Inspection of threaded connections will be according to the requirements listed above for small-bore and auxiliary piping. When selecting CMLs on threaded connections, include only those that can be radiographed during scheduled inspections. 小口径和辅助管道检验要求适用于带螺纹连接检验.

CML位置选择: 仅包括那些可以在预定的检查时运用射线探伤的位置. 可能会因机械或疲劳导致损伤的螺纹连接,应 (1) 定期评估和考虑 (2)用较厚的壁代 替或 (3) 升级到焊接构件.

6.7 Inspection and Maintenance of Pressurerelieving Devices (PRDs) 泄压装置的检查和维护

6.7.1 General 总则 PRDs shall be tested and repaired by a repair organization experienced in relief valve maintenance. PRDs should be inspected, tested, and maintained in accordance with API 576 泄压装置应当由有维修经验的维修机构按照API 576测试和修复

6.7.2 Quality Assurance Process for PRDs 质量保证过程 Each equipment repair organization shall have a fully documented quality assurance system. As a minimum, the following shall be included in the quality assurance manual: 设备维修机构应具有充分质量保证体系.

Each repair organization shall also have a fully documented training program that shall ensure that repair personnel are qualified within the scope of the repairs. 设备维修机构应具有充分质量保证体系.也有完善的培训计划,确保维修人 员在合格资质范围内进行相关维修校准.

6.7.3 PRD Testing and Inspection Intervals 测试和检验的时间间隔 6.7.3.1 General Pressure-relieving devices shall be tested and inspected at intervals that are frequent enough to verify that the valves perform reliably in the particular service conditions. 测试和检查的时间间隔足够确保能在特定服务的条件下 可靠地运行.

6.7.3.2 Unless documented experience and/or an RBI assessment indicates that a longer interval is acceptable, test and inspection intervals for pressure-relieving devices in typical process services should not exceed: 除非考虑经验证明/或RBI评估要求,一般检验间隔不大于:  five years for typical process services, 典型的流程服务-5年  ten years for clean (non-fouling) and noncorrosive services. 清洁和非腐 蚀性的服务-10年

82)All process piping systems must be categorised into different classes. On what are the classifications selection based? a) b) c) d)

Requirements of jurisdiction and the proximity of population areas Potential safety and environmental effects should a leak occur Liability to the owner-user and the requirements of the jurisdiction Access to the systems for inspection and closeness to population areas

83)Listed below are several examples of a CLASS 1 piping system. Which one does not belong? a) b) c) d)

Anhydrous hydrogen chloride; Hydrofluoric acid Piping over or adjacent to water and piping over public throughways Distillate and product lines to and from storage and loading

84)Of the three classification of piping systems, which includes the majority of unit processes and selected off-site piping? a) b) c) d)

Class 3 Combination of classes 1 and 2 Class 1 Class 2

85)Class 3 piping is described as being in services: a) With the highest potential of resulting in an immediate emergency if a leak occurs. b) That are flammable but do not significantly vaporise when they leak and are not located in high-activity areas c) That are not flammable and pose no significant risk to populated areas d) That are not in classes 1 and 2.

85)Class 3 piping is described as being in services: a) With the highest potential of resulting in an immediate emergency if a leak occurs. b) That are flammable but do not significantly vaporize when they leak and are not located in high-activity areas c) That are not flammable and pose no significant risk to populated areas d) That are not in classes 1 and 2.

86)Who establishes inspection interval for thickness measurements, external visual inspections and for internal and supplemental inspections? a) b) c) d)

Piping engineer Owner-user or the inspector Chemical Engineer Piping engineer and the jurisdiction

87)Thickness measurement inspection should be scheduled based on the calculation of not more than a) One half the remaining life determined from corrosion rates or the maximum interval of 5 years whichever is shorter. b) One half the remaining life determined from corrosion rates or the maximum interval allowed by API 570 in Table 1, whichever is shorter c) One fourth the remaining life determined from corrosion rates or the maximum interval of 10 years whichever is shorter. d) One quarter the remaining life determined from corrosion rates or the maximum interval allowed by API 570 in Table 1, whichever is shorter.

88)For external inspections for potential corrosion under insulation (CUI) on Class 1 systems, the examination should include at least __________ percent of all suspect areas and __________ percent of all areas of damaged insulation. a) b) c) d)

50, 75 50, 33 75, 50 25, 10

89)Piping systems that are known to have a remaining life of over __________ years or that are protected against external corrosion need not have insulation removed for the periodic external inspection. (2013 June) a) b) c) d)

10 15 5 20

90)For Class 3 piping systems, the examination for corrosion under insulation (CUI) should include at least __________ percent of all suspect areas. a) b) c) d)

50 30 10 0

91)For Class 2 piping, the extent of CUI inspections on a system operating at – 45oF will be: a) b) c) d)

75% of damaged areas, 50% of suspect areas 50% of suspect areas, 33% of damaged areas 33% of damaged areas, 50% of suspect areas None of the above

92)Small bore piping (SBP) that is Class I shall be inspected (2013 June) a) b) c) d)

Where corrosion has been experienced At the option of the inspector To the same requirements as primary process piping Only if it has dead legs

94)If an inspector finds threaded small bore piping (SBP) associated with machinery and subject to fatigue damage, he should: (2013 June) a) Plan periodically to assess it and consider it for possible renewal with a thicker wall or upgrade it to welded components. b) Inspect it only if it is corroded and the class of service requires an inspection. c) Call for dismantling the threaded joints for close inspection to determine if any cracks are in the roots of the threads. d) Have all the threaded piping renewed at each inspection period.

93)Inspection of small bore piping (SBP) that is secondary and auxiliary (associated with instruments and machinery) is a) b) c) d)

Only required where corrosion has been experienced Optional Only if it has dead legs Only if it is threaded