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.
Keywords: reverse simulation, cathodic protection system, CP, ICCP, impressed current, coating
defects, BEM