Comparative analysis between internal and external inspection data for high temperature crude oil pipeline

This paper targets at identifying the pros and cons of the internal and external inspection in evaluating external corrosion pipeline. Taking a section of certain crude oil pipeline from station A to station B as the studying object, a comparative analysis between the external corrosion pipe identified through the inside inspection and the data evaluation results from external inspection is conducted. The results show that the corrosion pits outside the pipeline are far more than the defect points in the external coating. Due to cathodic protection, the pipe body at the defect points is good, without obvious corrosion. The corrosion risk points outside the pipeline are distributed in the disbonding coating area. The internal inspection data can be used to evaluate the coating disbonding degree, while existing external inspection techniques have some limitations. In view of the limitations, it is proposed that in the external inspection and daily management of pipeline, direct excavation should be done in larger scale to evaluate the effectiveness of external corrosion control measures of the pipeline to make sure safe operation.