一起液化天然气罐车罐体脆裂事故分析

Research on the Brittle Fracture of a LNG Tanker

某单位一液化天然气罐车罐体发生泄漏,检查发现罐体后封头外壳局部脆裂。文中通过宏观检查、化学成分分析、金相检验、无损检测、气密性试验等技术手段进行分析,提出外壳局部脆裂是由于液位计气相管接管与管座接头连接焊缝处断裂,导致低温液化天然气泄漏所致,而接管断裂是在双向弯曲应力作用下产生疲劳裂纹并扩展所致。最后,提出了事故的有效预防措施。

A LNG tanker leaked because of the local brittle fracture in the rear head of tank was happened. In this paper, a lot of methods were used to analyze the cause, such as macro examination, metallographic test, nondestructive testing, gas-tightness test and so on. It was found that the fracture in the welded joint between the gasphase pipe of liquid-level gauge and the socket connection caused the fracture in the rear head, and the biaxial bending stress caused the fracture of the welded joint. The risk preventive measures were given at last.