Adaptive optimization of cathodic protection for pipelines under AC-induced interference: integrated electrochemical–electromagnetic analysis

Purpose This study aims to develop an integrated methodology to assess and optimize cathodic protection (CP) for buried pipelines exposed to alternating current (AC) interference from high-voltage transmission lines, ensuring protection efficiency while minimizing energy output. Design/methodology/approach A model of a 400 kV transmission line parallel to an X70 steel pipeline was used to compute induced AC current densities. Electrochemical impedance spectroscopy and polarization tests were performed on X70 steel under AC densities of 0, 100 and 200A/m² to determine corrosion kinetics. These parameters were integrated into a finite element CP model. A spline-based optimization algorithm was then applied to identify the minimum CP current required to achieve = 99.9% protection efficiency. Findings Increasing AC interference significantly reduces CP efficiency, evidenced by increased corrosion current densities, reduced charge transfer resistance and localized depolarization zones. The optimization algorithm revealed a nonlinear relationship between induced AC density, CP current and protection index, enabling adaptive current adjustment. This dynamic method offers a more accurate and energy-efficient approach compared to static CP criteria. Originality/value Unlike conventional static approaches, this work dynamically integrates exvperimentally derived electrochemical parameters with electromagnetic modeling and numerical optimization. The outcome is a validated framework for site-specific, energy-efficient CP management under variable AC interference, providing a practical decision-support tool for pipeline operators.