A Boundary Condition Model for Numerical Simulation for Cathodic Protection of an Underground Pipeline With Coating Defects

ABSTRACT Cathodic protection effectiveness is usually evaluated by protection potential, which can be calculated by a numerical simulation method. Its accuracy depends on the accuracy of the boundary condition description of the coated pipeline. This paper proposes an equivalent description model (equivalent method 2) for buried pipelines with coating defects. Through example comparison, the calculated results of directly constructing actual coating defects and the equivalent method based on uniform protection efficiency boundary conditions (equivalent method 1) are compared. The research results show that the widely used equivalent method 1 in the literature is only applicable to the calculation of pipe‐to‐soil potential of pipelines under constant anode output conditions. However, the equivalent method 2 proposed maintains highly consistent results with the actual coating defect model in the calculation of parameters such as pipe‐to‐soil potential, potential at ground surface, and sacrificial anode output current, with an error of less than 0.13%.