DC Interference Mitigation Project for Meishi Branch Pipeline & AC Interference Mitigation Projects for Huizhou, Guangzhou and Foshan

Based on data from cathodic protection remote monitoring equipment, special stray current surveys and quarterly cathodic protection inspections, Guangdong Dapeng LNG Co., Ltd. found three under-protected sections with substandard cathodic protection potential on the Meishi Branch Pipeline. Four segments of the Huizhou Branch Pipeline had induced AC voltage exceeding 15 V, with a maximum value of 17.35 V. Three pipeline sections in Guangzhou and Shenzhen showed excessive AC current density. A 1 cm² corrosion coupon was buried for long-term monitoring (more than 15 days), followed by 24-hour continuous measurement. The average interference current density was 527 A/m², and the peak value reached 636 A/m². After on-site verification, construction works for DC interference mitigation on the Meishi Branch Pipeline and AC drainage remediation in Huizhou, Guangzhou and Shenzhen are required to reduce pipeline corrosion risks.