Evaluation on Cathodic Protection Effect of Long-Distance Pipeline in Xinjiang Oil Field

On the basis of the investigation on the operating conditions of the pipeline and the operating environment of the cathodic protection system，the typical pipelines and test points were selected according to the principles of universality，representativeness and pertinence，and the corrosion rate and cathodic protection degree of the pipeline were measured by the on-site coupon hanging to evaluate the cathodic protection effect.Results showed that the corrosion rate of the pipeline was significantly lower than 0.01 mm/a and the protection degree was above 85%after applying cathodic protection in accordance with the minimum protection potential and cathode potential negative offset criteria specified in GB/T 21448-2017.The overall cathodic protection effect was good.For pipelines with high resistivity to soil，100 mV cathode potential negative offset criterion was recommended.In the actual operation process of pipeline cathodic protection，soil microorganism amount and types，stray current and the maximum protection potential needed to be heavily monitored for timely adjustment of the cathodic protection potential of the pipeline for the purpose of avoiding relatively serious uniform corrosion，local corrosion，hydrogen damage and unnecessary waste of resources.