埋地燃气管道与钢质套管连接状态判定

Determination of Connection State between Buried Gas Pipeline and Steel Casing

针对钢质套管与穿越段燃气管道的连接状态判定进行研究,通过调研国内外标准,对判定方法进行总结,结合上海某现场,对国外标准中推荐方法进行测试检验。对于套管空间内有无电解质可通过安装水位监测装置确定;套管与内管之间是否发生金属接触,可通过电位测试、内阻测试及套管去极化测试进行判断。当电位差测试结果大于100 mV,内阻测试结果大于0.01Ω或者内管-参比电极电位不存在与套管-参比电极相同幅度的正偏时,可认为套管与内管之间未发生金属接触。相反,若确定存在金属接触,可进行4线IR降测试,以确定接触位置,从而准确分析出套管与内管的连接状态。

The determination of the connection status between steel casing and gas pipeline in the crossing section is studied.The determination method is summarized by investigating the domestic and foreign standards.Combined with a site in Shanghai,the recommended methods in foreign standards were tested and verified.The presence or absence of electrolyte in the casing space can be determined by installing a water level monitoring device.Whether metal contact occurs between the casing and the inner pipe can be judged by the potential test,internal resistance test and casing depolarization test.When the potential difference test result is greater than 100 mV,the internal resistance test result is greater than 0.01Ω,or the inner pipe-reference electrode potential does not have a positive deviation of the same amplitude as the casing-reference electrode,it can be considered that there is no metal contact between the casing and the inner pipe.On the contrary,if it is determined that there is metal contact,4-wire IR drop test can be performed to determine the contact position,thereby accurately analyzing the connection state between the casing and the inner pipe.