The pipeline pipe-to-soil potential at Hayilian is up to-2 290 mV(CES)and above, which is much higher than the relevant standard.The cause of the high protective potential is analyzed to prevent to prevent the damage to the pipeline due to the hydrogen evolution.Combined with the environment of export pipeline at Hayilian, the external disturbance voltage and current to pipelines are tested and analyzed.At the same time, the potential test is carried out by using the near-reference electrode method combined with current interruption method, and the influence of high soil resistance which leads IR drop on the negative potential is analyzed.The results show that the export pipeline at Hayilian is not affected by stray current.On the contrary, high resistance of the test circuit is the main cause of the ultrahigh potential;if no power failure occurred to the near-reference coupon, the potential caused by loop resistance R can be reduced by about 500 mV, while in case of power failure, the potential will be further reduced by 550 Mv, which proves that the pipe-to-soil protective potential shall be measured by combination of near-reference electrode method with coupon current interruption method.%哈一联外输管线管地电位达到-2 290 mV(CES)以上,远高于相关标准要求值.为分析哈一联外输管线保护电位超高原因,防止析氢作用对管线的损害,结合哈一联外输管线所处的环境,对管线外界干扰电压电流进行测试分析;同时采用近参比电极法与试片断电法相结合进行电位测试,分析高土壤电阻带来的IR降对管地电位偏负的影响.结果表明:哈一联外输管线基本不受外界杂散电流干扰,测试回路的高电阻降是导致电位超高的主要原因;近参比试片不断电情况下,可以降低由回路电阻R造成的电位500 mV左右,试片断电时,电位进一步降低550 mV,证明需要用近参比电极法与试片断电法结合测量本管线的管地保护电位.
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