某平台天然气出口管线法兰螺栓断裂失效分析

针对某平台天然气接触塔出口管线隔离球阀法兰螺栓断裂失效问题，通过宏观分析、理化性能检测、微观及能谱分析等方法，对断裂螺栓和未断裂螺栓进行对比分析。同时，综合现场作业工况，得出螺栓断裂失效原因。结果表明，螺栓材料脆性大，在海洋大气环境长期服役过程中表面涂层逐渐失效，在腐蚀和应力集中的双重作用下，局部发生应力腐蚀开裂，最终导致断裂失效。

Fracture Failure Analysis of Flange Bolt of Natural Gas Outlet Pipeline of a Platform

In view of the fracture failure of the flange bolt of the isolation ball valve at the outlet of the natural gas contact tower of a platform, the fracture bolt and the unbroken bolt were compared and analyzed by the methods of macro analysis, physical and chemical performance testing, micro analysis and energy spectrum analysis. At the same time, the reason of bolt fracture failure is obtained by considering the working condition on site. The results show that the bolt material is brittle, and the surface coating gradually fails in the long-term service in the marine atmospheric environment. Under the dual action of the corrosion and stress concentration, local stress corrosion cracking occurs, which eventually leads to fracture failure.