Evaluation Methods of Aging of Corrosion Resistant Layer on In-service Oil and Gas Pipeline

Mathematical model reflecting the quality change of coating was built to study and evaluate the quality of corrosion resistant layer on in-service long-distance oil and gas pipeline, the relationship between the transition resistance of corrosion resistant layer and cathodic protection potential distribution of long-distance oil and gas pipeline was analyzed, the dropout situation of corrosion resistant layer was understood theoretically. At the same time, potential-distance curve was drawn according to standard pipe ground potential (P/S) testing and measured data from the project site, special parameters of the corrosion resistant layer and attenuation coefficient of the potential along the pipeline were calculated. Condition of the corrosion resistant layer on in-service pipeline was assessed, so as to provide an appropriate basis for the pipe network maintenance and safe operation guidance of the pipeline.