低温储罐三通切换阀管件失效分析

Failure Analysis on Three Switching Valve Fittings of Cryogenic Tank

在低温储罐定期检验中,发现储罐底部一个三通切换阀管件上存在多处裂纹及泄漏现象。通过对失效件进行宏观检验、化学成分、电镜扫描、金相组织、腐蚀产物能谱、非金属夹杂物含量、显微硬度等进行测试,结果表明:管件材质低于设计要求,管件承受载荷及应力作用,存在Cl-等奥氏体不锈钢腐蚀敏感介质,造成该处奥氏体不锈钢管件应力腐蚀失效。

Cracks and leaks were found on the switching valve during a periodic inspection on a cryogenic tank. The test results showed the material of the tube didn＇t match the requirement of the standard through macroscopic examination, chemical composition, SEM, metallurgical analysis, EDS Analysis and micro-hardness test. It was concluded that the stress corrosion lead to the failure on the co-effect of load and stress, chemical composition and the corrosion of CI-.