API510/570-Ex A PI510/570-Exam am
Figure Figure 4-74 – Close-up Close-up of Tee Tee CUI of a Tee in Figure Figure 4-73 after insulation removal.
API510/570-Ex A PI510/570-Exam am
Figure 4-75 – CUI of a 30 inch CS Butadiene Butadiene line showing showing highly localized corrosion which could only only be found by stripping the entire entire line. Note the 0.25 in (6.5 mm) mm) diameter hole at arrow
API510/570-Exam
Figure 4-76 – CUI of nozzle on a bottom head.
API510/570-Exam
Figure 4-77 – CUI of nozzle on a top head.
API510/570-Exam
Figure 4-78 – CUI of vessel wall. Note leak at arrow.
API510/570-Exam
Figure 4-79 – CUI at attachment supports and vessel head.
API510/570-Exam
Figure 4-80 – CUI of CS level bridle.
API510/570-Exam
保温层下腐蚀学习重点: 1. 温度: 操作温度 2. 受影响材料:碳钢,低合金钢,奥氏体不锈钢,双相不锈钢, 3. 损伤原理: 潮湿腐蚀(碳钢,低合金钢)/氯化物应力腐蚀开裂(奥氏体不锈钢/双 相不锈钢). 4. 关键因素: 易感温度(碳钢 -10oF~350oF) / (奥氏体不锈钢 140oF~400oF), 损 坏保温层,保温层突漏点(T点,垂直高点,阀门突漏点) 5. 预防/缓解:表面处理和适当的涂料应用,低氯绝缘应使用在300系列不锈钢, 6. API 510/570 考试学习项.
API510-Exam
4.3.4 Cooling Water Corrosion 冷却水的腐蚀 4.3.4.1 Description of Damage General or localized corrosion of carbon steels and other metals caused by dissolved salts, gases, organic compounds or microbiological activity. 溶解的盐, 气体, 有机化合物的, 或微生物的活动引起的均匀与局部腐蚀. 4.3.4.2 Affected Materials Carbon steel, all grades of stainless steel, copper, aluminum, titanium and nickel base alloys.
API510-Exam
4.3.4.3 Critical Factors a) Cooling water corrosion and fouling are closely related and should be considered together. Fluid temperature, type of water (fresh, brackish, salt water) and the type of cooling system (once-through, open circulating, closed circulating), oxygen content, and fluid velocities are critical factors. b) Increasing cooling water outlet temperatures and or process side inlet temperatures tend to increase corrosion rates as well as fouling tendency. c) Increasing oxygen content tends to increase carbon steel corrosion rates. d) If the process side temperature is above 140 F (60 C), a scaling potential exists with fresh water and becomes more likely as process temperatures increase and as cooling water inlet temperatures rise. Brackish and salt water outlet temperatures above about 115 F (46 C) may cause serious scaling. e) Fouling may occur from mineral deposits (hardness), silt, suspended organic materials, corrosion products, mill scale, marine and microbiological growth. °
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API510-Exam
f) Velocities should be high enough to minimize fouling and drop out of deposits but not so high as to cause erosion. Velocity limits depend on the tube material and water quality. g) Low velocities can promote increased corrosion. Velocities below about 3 fps (1 m/s) are likely to result in fouling, sedimentation and increased corrosion in fresh and brackish water systems. Accelerated corrosion can also result from dead spots or stagnant areas if cooling water is used on the shell side of condensers/coolers rather than the preferred tube side. h) 300 Series SS can suffer pitting corrosion, crevice corrosion and SCC in fresh, brackish and salt water systems.
API510-Exam
i) Copper/zinc alloys can suffer dezincification in fresh, brackish and salt water systems. The copper/zinc alloys can suffer SCC if any ammonia or ammonium compounds are present in the water or on the process side. j) ERW carbon steel may suffer severe weld and/or heated affected zone corrosion in fresh and/or brackish water. k) When connected to a more anodic material, titanium may suffer severe hydriding embrittlement. Generally, the problem occurs at temperatures above 180 F (82 C) but can occur at lower temperatures. °
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API510-Exam
Copper/zinc alloys can suffer dezincification
API510-Exam
4.3.4.4 Affected Units or Equipment Cooling water corrosion is a concern with water-cooled heat exchangers and cooling towers in all applications across all industries. 4.3.4.5 Appearance or Morphology of Damage a) Cooling water corrosion can result in many different forms of damage including general corrosion, pitting corrosion (Figure 4-81), MIC, stress corrosion cracking and fouling. b) General or uniform corrosion of carbon steel occurs when dissolved oxygen is present. c) Localized corrosion may result from under-deposit corrosion, crevice corrosion or microbiological corrosion. d) Deposits or crevices can lead to under-deposit or crevice corrosion of any of the affected materials.
API510-Exam
e) Wavy or smooth corrosion at nozzle inlets/outlets and tube inlets may be due to flow induced corrosion, erosion or abrasion. f) Corrosion at ERW weld areas will appear as grooving along the weld fusion lines. g) Metallurgical analysis of tube samples may be required to confirm the mode of failure.
API510-Exam
Crevice corrosion
API510-Exam
Crevice corrosion
API510-Exam
microbiological corrosion / MIC
API510-Exam
microbiological corrosion / MIC
API510-Exam
microbiological corrosion / MIC