Remote Field Eddy Current NDT in Tubes Using Anisotropic Magneto-Resistors

Abstrac t This paper presents a measuring system capable of detecting longitudinal and circumferential defects using remote field eddy current in stainless steel tubes with an AMR sensor. An excitation coil is required with a time varying current to produce a magnetic field that penetrates the material on test. The experimental results from both defects are compared with other results for the same material without any defect. The obtained results represent the AMR output magnetic field amplitude and the phase difference between the magnetic field produced by the excitation coil and the magnetic field measured by the AMR sensor. The paper also presents the defect signature for each defect.