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对一段发生泄漏的天然气长输管道进行失效分析。在排除机械损伤和外部因素基础上,通过防腐层实验、化学成分分析、金相组织观察、天然气组分检测、腐蚀产物XRD谱,分析了管道内腐蚀穿孔形成的原因。结果表明,管道内腐蚀穿孔是由氧腐蚀、CO_2腐蚀、硫酸盐还原菌腐蚀共同造成的。管道敷设后与投产前内部的空气、投产后天然气中的CO_2、管道中的水和泥土在管道腐蚀中起到了关键作用。提出了需要采取开挖检测、更换腐蚀管段、外加电流法阴极保护、进行管道清管与内检测、选择缓蚀剂等措施。
Failure analysis of a long-distance natural gas pipeline that leaked. On the basis of eliminating the mechanical damage and external factors, the causes of corrosion and perforation in the pipeline were analyzed through the experiments of anticorrosive layer, chemical composition analysis, microstructure observation, natural gas composition and XRD patterns of corrosion products. The results show that the corrosion perforation in the pipe is caused by the combination of oxygen corrosion, CO 2 corrosion and sulfate reduction bacteria corrosion. The air inside the pipeline after it is put into operation and before it is put into production, the CO_2 in the natural gas after it is put into production, and the water and soil in the pipeline play a key role in pipeline corrosion. Proposed the need to take excavation testing, replacement of corrosion pipe, plus the current cathodic protection, pipe cleaning and internal testing, corrosion inhibitor selection and other measures.