Abstract
Tie-Da crude oil pipeline, which is located in the north east corner of China, was put into operation in September 10, 1975, with long-term operation of low throughput, and never has run tools for internal inspection. Tie-Da crude oil pipeline is closely parallel with An-Da crude oil pipeline and is severely affected by dynamic stray currents from the operation of nearby Ha-Da electrified railway system between Anshan and Dashiqiao. According to NACE SP0502, an applicability research was carried out in Tie-Da pipeline to assess and reduce the impact of external corrosion on pipeline integrity. During combined CIPS + DCVG survey, surveyors installed three GPS synchronized current interrupters at three CP current sources, simultaneously the stationary loggers were installed at the test station no more than 5km to record the effect of stray current on the pipe-to-soil potential. By utilizing this information to correct the recorded CIPS data, surveyors obtain more accurate polarization potential to evaluate the level of cathodic protection and effectively identify and address corrosion activity. The assessment result indicates that accurate location coating corrosion activity of indirect inspection, there is no obviously thinning of pipeline wall caused by external corrosion, and ECDA is effective. Attention should be paid to quality control in the constructing process, and give some advices for attention in ECDA usage.
