In this paper, a case study on AC interference measurement and mitigation was introduced. A buried pipeline was running in parallel with 500 kV high-voltage alternating current (HVAC) transmission line for about 10 km. The distance between them was about 25~600 m. Field test showed that the maximum AC voltage was 44.3 V and AC current density was 1248 A/m2 at cathodic protection (CP) polarized potential of -0.90 VCSE ~ -0.95 VCSE. Overall, these results indicated that the buried pipeline suffered serious AC interference. Therefore, corrosion coupons were buried and electrically connected with the pipeline to investigate AC corrosion, which was analyzed according to weight loss test results and corrosion morphology analyses. Based on the collected information, numerical simulation model was established and adjusted to meet field test results. And then, mitigation schemes were designed and optimized with the help of the numerical simulation. The final mitigation scheme was got to reach the mitigation target.

Subject
Ribbons, CP coupons, Voltage, Cathodic protection, Pipelines, HVAC, Corrosion products, Transmission lines, Current densities, Alternating current corrosion, Below ground pipelines, AC interference, Corrosion coupons
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2021
Association for Materials Protection and Performance (AMPP)
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