Monitoring and prevention of AC stray current corrosion in a natural gas pipeline

A long-distance buried steel natural gas pipeline runs parallel to and intersects high-speed railways and high-voltage power lines multiple times, creating a complex electromagnetic environment with severe AC stray current interference. This significantly raises the risk of electrochemical corrosion, making it urgent to quantify corrosion interference intensity and develop targeted protection strategies. In this study, data loggers were employed to continuously monitor the AC current density of the pipeline to assess the corrosion risk induced by AC current in the buried steel pipeline. For segments identified with high corrosion risk, a combined drainage system of "solid-state decouplers + deep-well grounding electrodes" was designed and implemented. The effectiveness of this strategy in mitigating AC corrosion was confirmed by comparing monitoring data before and after remediation. The peak AC current density at high-risk monitoring points reached 566.84 A/m², 5.7 times the 100 A/m² safety threshold specified in"Standard for AC interference mitigation of buried steel pipelines" (GB/T 50698—2020). After remediation, the average AC corrosion current density at all test posts dropped below 30 A/m², fully meeting the standard requirements. The combined drainage system of"solid-state decouplers + deep-well grounding electrodes"effectively suppresses severe AC stray current interference, achieving pipeline corrosion protection.