Verification experiments for high-precision Above Ground Marking system

Magnetic Flux Leakage Detector is typically used in pipeline applications involving the use of a device that passes through the pipeline to collect various data with respect to the condition of the pipeline, such as crack, corrosion, and deformation. As a crucial part of the Magnetic Flux Leakage Detector, Above Ground Marking system eliminates accumulated errors caused mechanical construction, turning or slippage of the miles round of magnetic flux leakage detector. In this paper, high-resolution clock is used as common time base of the master clock and above ground marker (AGM) to improve the accuracy of defects location. Experiments were performed to test (1) influence on inspection data when AGMs were put along the pipe with different angles; (2) specification and stability of above ground marker and master clock system. Results showed that location error will occur when AGM was angular placed along the pipe.