Investigation on pulsed eddy current testing of metal corrosions based on focusing probe

The insulated pressure pipeline is prone to local corrosions (CUI). Pulsed eddy current testing (PECT) can detect the insulated pipes with a metal cladding layer, which has been widely concerned. In this paper, a focusing probe is designed by numerical simulation, and the sensitivity of the probe is studied by experiment. In the simulation, the positions of the detection coils are determined by the distribution of magnetic flux density around the probe and the eddy current density on the specimens. The experimental results show that the designed focusing probe can effectively detect the local corrosions and thin stainless-steel plates under insulation. Also, the fitting curve between the varying thickness of stainless-steel plates and the amplitude of the induced voltage, and to quantitatively evaluate the thickness of steel plates, the imaging detection of the thickness is obtained.