某油管自墩粗端,距管端头螺纹约211 mm处发生断裂。通过宏观观察、化学成分分析、断口分析、金相检验等方法对油管断裂原因进行了分析。结果表明:操作环境中存在H₂S和CO₂,油管显微组织中存在非金属夹杂物,油管上由工具和卡具造成的机械损伤产生局部硬化和应力集中,使油管在湿H₂S环境下产生了应力腐蚀开裂。

A tubing fractured at about 211 mm away from the end thread of the pipe from the thick end of the pier. The fracture causes of tubing was analyzed by macroscopic observation, chemical composition analysis, fracture analysis and metallographic examination. The results show that there were H₂S and CO₂ in the operating environment, non-metallic inclusions in the microstructure of the tubing, mechanical damage caused by tools and fixtures on the tubing produces local hardening and stress concentration, resulting in stress corrosion cracking of the tubing under wet H₂S environment.