埋地天然气管道泄漏失效分析

Leakage Failure Analysis of Buried Natural Gas Pipeline

某采气厂天然气管道发生了穿孔泄漏失效,为了确定该管道泄漏失效原因,对泄漏钢管的外观形貌、化学成分、金相组织、开路电位、力学性能和微观形貌等进行了试验分析。结果表明,泄漏钢管材料的化学成分和拉伸性能均符合GB/T 8163—2018标准的要求。该管道泄漏是由于所输送天然气中的固体不溶物沉积后与管道钢管内壁裸露金属形成大阴极、小阳极腐蚀电池,使暴露金属发生了阳极溶解。另外,由于钢管内流体中的固体颗粒冲刷钢管内表面,钢管内表面金属阳极快速溶解,从而使钢管管壁逐渐减薄,最终导致该钢管管壁局部腐蚀穿孔失效。

A perforation leakage failure occurred in a natural gas pipeline in a gas production plant.In order to determine the cause of the pipeline leak failure,the appearance,chemical composition,metallographic structure,open circuit potential,mechanical properties and microscopic morphology of the leaked steel pipe were analyzed.The results show that the chemical composition of the leaked steel pipe material meets the requirements of GB/T 8163—2018 standard,and the tensile properties of the material meet the requirements of GB/T 8163—2018 standard.The leakage of the pipeline is caused by the formation of a large cathode and a small anode corrosion battery between the deposition of solid insoluble matter in the transported natural gas and the exposed metal on the inner wall of the pipeline steel pipe,which causes the anode dissolution of the exposed metal.In addition,because the solid particles in the fluid in the steel pipe erode the inner surface of the steel pipe,the metal anode on the inner surface of the steel pipe is quickly dissolved,so that the wall of the steel pipe is gradually thinned,and eventually the local corrosion perforation of the steel pipe wall occurs.