PVC反应器三通接管法兰泄漏原因分析

Leakage Failure Analysis on Tee Pipe Flange in PVC Reactor

针对PVC反应器三通接管法兰泄漏失效,进行了宏观、微观形貌及化学成分分析;力学性能测试以及应力校核,结果表明,法兰的失效模式为应力腐蚀开裂。由于法兰含碳量偏高,含铬偏低,硬度偏高,热影响区晶粒粗大,导致材料抗应力腐蚀能力下降,最终法兰在氯离子和局部应力共同作用下发生应力腐蚀开裂。

The cause of the leakage of tee pipe flange was studied by macro-morphology, chemical analysis, SEM, metallographic and stress analysis. The results indicate that the failure of the flange is due to the stress corrosion cracking. The poor mechanical properties and stress corrosion resistance can contribute to higher carbon content and hardness, lower chromium, and coarse grain size in HAZ. Finally, the stress corrosion cracks occur under chloride ion and higher local stress concentration.