Remote-field eddy current responses to axial and circumferential slots in ferromagnetic pipe

Remote-field eddy current (RFEC) responses to axial and circumferential slots of various widths and depths cut in a sample of 2 percent Mn steel line pipe are reported. Responses are approximately linear with depth, except for through-wall axial slits, which give significantly greater signals. Although circumferential slots should perturb the eddy current less, they give greater RFEC responses