Simulation of Pipeline Inner and Outer Defect Recognition Based on Saturated Low Frequency Eddy Current Technique

Eddy current testing (ECT) is a normally used nondestructive testing method. However, because of the skin effect, it is difficult to detect the deeper defects by ECT. Using saturated low frequency eddy current technique (SLFECT), the structure is magnetized to saturation by adding a direct magnetizing field; in addition, the relative permeability is decreased and the skin effect is reduced. In this paper, based on the thesis of SLFECT, the model of SLFECT is built by finite element method. The simulation results indicate that the crack in different depth, inner and outer corrosions can be detected obviously; moreover, using the impedance analysis method, the depth of crack and position of corrosion can be recognized.