油气管道杂散电流干扰的缓解措施与评价准则评析

Mitigating Measures and Evaluation Criterion of Direct Current(DC) Interference on Oil & Gas Pipelines

对比分析了国内外关于油气管道杂散电流干扰的几部标准中提到的杂散电流干扰的判断准则和缓解措施,介绍了阴极保护准则的最新研究结果。分析结果认为:各国标准对于杂散电流干扰的基本认识比较一致,但是其判断准则和缓解电干扰的具体方法有较大的差异。电位梯度法判断杂散电流干扰可能需要附加土壤电阻率数据,安装绝缘接头的缓解措施可能会产生不利影响,正电位平均值法评定准则并不能评价管道受到的电干扰腐蚀危险性。绝大多数情况下,当管地电位满足-850 mV on/off电位时,管道最大点蚀速率均可以降到0.3 mm/a以下。当管地电位不能满足-850 mV on/off电位时,需要防腐工程师根据现场测试数据评价管道遭受点蚀的危险性。

The DC stray current interference and determination criteria in several domestic and foreign standards （m I）C stray current interferenee on pipelines and mitigation measures are compared and analyzed, and the latest study achievements are described. Although the fundamental views on DC stray cun^nt interterence were consistent, specific measures and criteria on how to estimate and mitigate DC interference are very different between the standards. Soil resistivity is needed when potential gradient is used to evaluate the degree nf DC interference. Installation of insulation joint to mitigate DC interference may have a negative impact. The criterion of the average positive potential can not be used to evaluate the corrosion risk the pipeline is facing. Recent study indicates that the maximum pining corrosion rate can be reduced to lower than 0.3mn V/vr when the - 850 mV on/off potential is achieved and that more field test data is needed to estimate the pitting corrosion danger on pipeline when the - 850 mV on/off potential can not be achieved. It is necessary for corrosion engineer to access the risk of possible pitting corrosion of pipelines based upon fiebl testing data.