A Computational Approach for Assessing Coating Performance in Cathodically Protected Transmission Pipelines

Abstract

Abstract The paper presents an efficient and accurate 3D computational approach for assessing the quality of the coating of sub-surface underground transmission metallic pipelines under cathodic protection control. The CP system consists of a series of Impressed Current anode beds connected to the pipeline and distributed along its length. The computational approach addresses the problem of non-homogeneous electrolyte, by regarding the soil as a multi-layered region which may be thin in comparison with the characteristic length of the pipeline (typically tens of kilometres). The model considers the non linear electrode kinetics on the metal surfaces in the form of polarisation data and also considers the internal resistance of the pipeline and other electrical connections. The aim of the simulation is to predict the status of the coating in contact with the electrolyte, and to estimate the size and location of coating defects given a minimal number of field potential measurements taken from surveys.