某集气管线穿孔失效原因分析

Cause analysis of perforation failure of a gas gathering pipeline

摘要:
目的确定四川某集气管线腐蚀穿孔的原因。
方法采用直读光谱仪、金相显微镜、X-射线衍射仪和扫描电镜及EDS能谱对失效样品进行检测，并对腐蚀环境进行了分析。
结果 ① 管体内壁存在大量腐蚀凹坑，管体金相组织为铁素体+珠光体，焊缝组织为针状铁素体，管基体的冶金质量、化学成分和力学性能符合标准; ②腐蚀产物为FeS和少量FeCO₃; ③气田水中存在硫酸盐还原菌(SRB)。
结论管线穿孔是SRB、H₂S、CO₂等因素共同作用的结果。

Abstract:
Objective The perforated corrosion sample of a natural gas gathering pipeline in Sichuan was studied to determine its failure reason.
Methods The failure samples were tested by direct-reading spectrometer, optical microscope, X-ray diffractometer, scanning electron microscope and EDS, and the corrosion condition was analyzed.
Results (1) A large number of corrosion pits can be seen on the inner surface of the pipeline. The matrix of the pipeline was ferrite plus pearlite, and the weld seam was acicular ferrite. Its metallurgical quality, chemical composition and mechanical properties meet the national standard requirements. (2) The corrosion products were FeS and FeCO₃. (3) SRB existed in the gas field water.
Conclusions The cause of pipeline perforation is the
result of SRB, H₂S, CO₂ and other factors.