Frequency Characteristics Analysis of Remote Field Eddy Current Testing on Ferromagnetic Pipes

Eddy current testing (ECT) method is widely used for defect detection in heat exchangers in steel and petrochemical plants. In practical usages, the remote ECT method is effective on external defect detection of ferromagnetic pipes. To clarify the detailed detection mechanism of the remote field ECT method, the frequency characteristics of the remote field ECT method on detecting an artificial external defect made on a ferromagnetic pipe specimen are measured and analyzed in detail by using the nonlinear eddy current analysis. Peak occurs directly under the defect under the same optimal frequency range in both analysis and measurement.