A remote field eddy current probe for outside inspection of pipe defects

A remote field eddy current (RFEC) probe for in-service inspection of pipe defects is presented. Firstly, based on finite element analysis, the probe is designed with an external and circumferentially aligned structure. Afterwards, the simulation model of RFEC testing for defect detection is established, and the quantitative relations of the inner diameter (ID) and outer diameter (OD) defect depth to the signal features are analysed. Finally, experimental verification is performed. The results show that: (i) the probe signal phase decreases almost linearly with the increase of ID or OD defect depth, which can be used to quantify defect depth; (ii) the ID or OD defect depth can be quantified respectively, but, due to the different sensitivity to ID and OD defects, it is still hard to quantify the depth when two types of defect exist simultaneously; and (iii) the defect orientation has little effect on the signal phase.