2017 Volume 58 Issue 4 Pages 641-645
Subjected to hoop stress and land movement load, the orientation of cracks on the surface of pipeline may be axial direction, circumferential direction or the others. In this paper, an electromagnetic Helmholtz-coil probe is presented to detect the oriented cracks on the surface of pipeline. A structure of equal-spaced TMR sensor array of the Helmholtz-coil probe is applied to scan the full circumference of the pipeline simultaneously in a single pass. The simulation and experiment results indicate that using the combination effect of the electric current perturbation and the magnetic flux leakage, the oriented crack can be mapped clearly.