The Corrosion Detection Methods of External Coating for Buried Pipe and Its Application

Three fault-location survey methods to external coating of buried steel pipe, first being PCM(pipeline current method), second being DCVG survey and TEM (temporary electromagnetic method), are introduced.These methods introduced in the paper can be used without field excavation. The survey results from PCM can be used to evaluate overall conditions of pipeline coating; DCVG can locate accurately coating faults; TEM can survey the metal weight loss and evaluate the corrosion conditions of the pipeline. The application cases with these three survey methods are given.