Finite element study of remote field eddy current methods for inner diameter and outer diameter pipeline defect classification

Abstract

Remote field eddy current (RFEC) methods are widely applied for detecting pipeline defects. However, current RFEC methods cannot distinguish inner diameter (ID) defects from outer diameter (OD) defects. In addition, existing RFEC probes are usually driven by an extremely low-frequency signal, which reduces the detection efficiency. To address these issues, a novel external RFEC probe is designed to improve the detection performance. First, the probe structure is designed using a simulation tool. Second, the excitation and structural parameters are optimally selected. Finally, the relationships between the signal features and the defect dimensions are analysed. The results show that the probe can realise the RFEC effect without shield cages, the exciting frequency is significantly improved and the phase angle can be used to classify ID and OD defects.