Development of Magnetic Eddy Current Testing for Opposite-Side Defect Detection in Ferromagnetic Steel Pipeline Inspection

Conventional Magnetic Flux Leakage Testing (MFL) and Eddy Current Testing (ECT) have the limitation that they cannot detect and distinguish both side defects in ferromagnetic pipe inspection. To overcome this limitation, Magnetic Eddy Current Testing (MEC) has developed. it can detect both side defects and distinguish between surface and opposite side defects. In this paper, MEC system was introduced, and field and coil impedance perturbation due to opposite defects and surface defects were analyzed for distinguishing two defects. The principle of distinguishing two defects was explained through the transformer circuit. Simulation and experiment were conducted, and results showed that MEC can distinguish far-side and near-side defect through measurement of phase variation in signal.