套管对埋地燃气管道阴极保护电位影响分析

Effects Analysis of Casing on the Cathodic Protection Potential in Underground Gas Pipelines

埋地燃气管道加装钢质套管若安装不合理,将影响套管内钢管的阴极保护电位,从而导致套管内主管道阴极保护失效。结合实际腐蚀检测案例,分析了套管内主管道腐蚀的影响因素,主要原因为钢质套产生的断路屏蔽和短路屏蔽效应。同时,给出了在套管中填充导电介质、套管内主管道加装镁阳极缠绕带,以及在套管内主管道加装保护电位检测装置等改造措施。实际应用结果表明,改造后的1 a运行期间未发现套管内主管道遭受电化学腐蚀。

If the steel casing on underground gas pipelines is not properly installed,it will affect the cathodic protection potential of the steel pipeline inside the casing and then it will lead to the failure of cathodic protection of the main pipeline inside the casing.According to the actual corrosion detection cases,the influencing factors of the main pipeline corrosion inside the casing are analyzed.The main reasons are open circuit shielding and short circuit shielding effect caused by the steel casing.At the same time,the reformation measures are given by filling conductive media in the casing,installing magnesium anode winding tape on the main pipeline inside the casing,installing a protective potential detection device on the main pipeline inside the casing and others.The actual application results indicate that no electrochemical corrosion was found on the main pipeline inside the casing during the 1 year operation period after the renovation.