某埋地碳钢管道腐蚀失效分析

Corrosion Failure Analysis of a Buried Carbon Steel Pipeline

针对某气田L360管道外壁发生的局部腐蚀现象,通过对腐蚀管段理化性能分析、土壤成分分析和硫酸盐还原菌(SRB)腐蚀试验等,系统地研究了该管道失效的原因。结果显示,该管材的化学成分、力学特性和金相组织均符合标准要求。分析表明,管体周围土壤含水率较高同时含有大量的SRB是导致局部腐蚀的主要原因,且随着时间延长产物膜不具备保护性,其与基材形成的腐蚀原电池加快了腐蚀进程。

In view of the local corrosion phenomenon on the outer wall of a L360 pipeline,the failure reason of the pipeline was studied through the physical and chemical analysis of the corroded pipe section,soil composition analysis and sulphate-reducing bacteria corrosion test.The results show that the chemical composition,mechanical properties and metallographic structure of the pipe meet the standard requirements.The high moisture content and large amount of sulphate-reducing bacteria in the soil around the pipe are the main causes of local corrosion.The product film does not protect with the time on,and the corrosion galvanic cell formed between the product and base metal speeds up the corrosion process.