Evaluation of transient eddy current oscillations response for thickness measurement of stainless steel plate

Detection of a wall thickness change in pipelines is extremely important to avoid unwanted leakages and accident reduction in industrial structures. In the present study, transient eddy current oscillation (TECO) nondestructive testing (NDT) method has been used to detect the thickness of stainless specimen. Damped free running oscillations that are generated by cyclic exchange of energy between a capacitor and an induction coil in the TECO probe, are used to induce the eddy currents into the test specimen. The resultant magnetic field is detected by using a Hall sensor in the vicinity of the test specimen. The experimental results are analyzed in the frequency domain by calculating the power spectral density (PSD) of the detected decay of oscillations response from the probe. Two features, peak frequency and −3 dB bandwidth of the PSD, are used to interpret the thickness variation in test specimen. The TECO method has been successfully applied to measure the thickness of stainless steel plates.