Protective Effect of 3PE Anti-corrosion Coating Associated with Cathodic Protection on Pipelines

Buried steel pipelines were protected by the method of 3PE anti-corrosive coating associated with cathodic protection. Different conditions, such as that 3PE anti-corrosive coating primer existsed, metal substrate exposed, metal exposed holes did not contact or contact completely with soil, were simulated. The relationship between cathodic current and potential was discussed, the influence of coating potential moved to negative analyzed too. The results show that the variation of cathodic protection current of the samples was bound up with the defect of the 3PE anti-corrosion coating of the samples, the ways contacted with soil and the impressed current. When the potential is higher that -0.85 V(CSE), it is difficult to prevent the samples from corrosion. When the potential moved to negative direction excessively, the protection of 3PE anti-corrosion coating was early invalidatied.