The Use of AC and DC Potential Mapping in the Evaluation of the Effectiveness of Cathodic Protection on Buried Coated Steel Pipelines with Holidays

Abstract

Potential fields formed by the alternating and direct currents flowing into a coating holiday on a buried steel pipeline were analyzed by means of the multi-electrode mapping method. Simulated field experiments demonstrated that the AC potential field analysis permits an accurate trenchless estimation of the location and the size of coating holidays, whereas the DC potential field analysis permits a correct trenchless assessment of the true level of cathodic protection at respective holidays. The effectiveness of the method was also demonstrated on the existing pipelines. Theoretical background and the results of field experiments are given.