某石化设备316L不锈钢材料失效原因分析及解决办法

Failure Cause Analysis and Solution of 316L Stainless Steel Material in a Petrochemical Equipment

某石油化工厂设备运行期间泄漏,紧急停车后对失效部位316L材料进行材质分析、金相检查等理化检验,结合腐蚀产物离子色谱分析结果及工艺条件,分析是氯离子混入工艺流程在滞流区沉积浓缩引发的316L不锈钢材料点蚀,在有拉应力存在的部位则有应力腐蚀开裂裂纹,点蚀穿孔及裂纹贯穿会导致泄漏。为使装置尽快开车,通过对设备材料及服役环境的分析,决定采用超支化聚合物涂料对设备内表面氯离子沉积区域涂敷保护,完工后经过约3年周期观察,涂层完好如初,保护区域内再没有出现腐蚀,由此证明将316L材料涂敷超支化聚合物涂料是一种及时有效的防护氯离子腐蚀的方法。

After an emergency shutdown,material analysis,metallographic inspection and other physical and chemical inspection were carried out on the 316L material at the failure site.Combined with the results of ion chromatography analysis of corrosion products and process conditions,the analysis showed that the pitting corrosion of 316L stainless steel material was caused by the deposition and concentration of chloride ions in the stagnant area when mixed with the process flow.Where there is tensile stress,there are stress corrosion cracking cracks,pitting perforation and crack penetration will lead to leakage.In order to enable the device to start operation as soon as possible,through the analysis of equipment materials and service environment,it was decided to use hyperplastic polymer coating to protect the chloride ion deposition area on the inner surface of the equipment.After about 3 years of periodic observation after completion,the coating was intact and no corrosion occurred in the protection area.It is proved that 316L material coated with hyperbranched polymer coating is a timely and effective method to protect against chloride ion corrosion.