Study on applicability of electromagnetic eddy current internal inspection for gas field gathering and transmission pipeline

The risk of internal corrosion failure of gathering and transmission pipeline in sour gas field is high, but due to small pipe diameter, low pressure and complex internal environment, the internal magnetic flux leakage detection is difficult to complete smoothly, and the corrosion condition of inner wall is unknown for a long time. In view of the above problems, two natural gas gathering and transmission pipelines are selected to carry out the field test of electromagnetic eddy current internal detection, and the effectiveness and detection accuracy of this technology in small-diameter, low pressure and complex internal environment pipelines are verified and analyzed through excavation. The test results show that due to the simple structure and small size of the equipment, the electromagnetic eddy current internal detector has superior trafficability and can be successfully implemented in natural gas gathering and transmission pipeline; Electromagnetic eddy current technology has high detection rate of internal corrosion defects, high detection accuracy of defect depth and width, but low detection accuracy of defect length and circumferential position; The electromagnetic eddy current internal detector is less affected by the moving speed of the equipment. Even under the condition of serious unstable speed, it can still ensure good defect detection rate and defect depth detection accuracy. The test results can provide data support for the popularization and application of electromagnetic eddy current internal inspection technology in gas field gathering and transmission pipeline in the next step.