Abstract DC stray currents may induce corrosion on buried carbon steel pipelines transporting methane even if in cathodic protection. According to international standard, anodic interference is unacceptable if the IR-free potential is more positive than the protection potential (−0.85 V CSE). But, duration and magnitude of the anodic peak is not defined. This paper describes results of laboratory tests performed in soil-simulating environment on cathodically protected carbon steel specimens suffering DC interference at varying peak current density, anodic potential and duration. Measured corrosion rate is always lower than the theoretical value predicted by Faraday Law. Consequently, it is possible to conclude that cathodic protection has a positive effect towards DC interference. A parameter Time Out of Protection has been defined as the period of time during interference where the potential is more positive than −0.85 V CSE; this factor has been correlated to the measured potential during DC interference.

中文翻译：

---

阴极保护和直流非稳态阳极干扰

摘要 直流杂散电流即使在阴极保护下，也会对输送甲烷的埋地碳钢管道产生腐蚀。根据国际标准，如果无 IR 电位比保护电位 (-0.85 V CSE) 更正，则阳极干扰是不可接受的。但是，阳极峰的持续时间和幅度没有定义。本文描述了在土壤模拟环境中对阴极保护碳钢试样在不同峰值电流密度、阳极电位和持续时间下遭受直流干扰的实验室测试结果。测量的腐蚀速率总是低于法拉第定律预测的理论值。因此，可以得出结论，阴极保护对直流干扰具有积极影响。参数超时保护被定义为干扰期间电位比 -0.85 V CSE 更正的时间段；该因素与直流干扰期间测得的电位相关。