Corrosion Reason for a Buried Gas Pipeline with 3PE Coating

The corrosion reasons of a gas pipeline with 3PE coating were analyzed by macro observation, soil environment testing, evaluation of cathodic protection and interference of alternating current (AC)/direct current (DC), and corrosion product analyzing. Results indicated that AC corrosion was most likely to be the cause of corrosion because of similar corrosion morphology, and the biggest AC current density was as high as 100 A/m2 induced by nearby electrified railway.