A Study on the Estimation of the Shapes of Axially Oriented Cracks in CMFL Type NDT System

Axially oriented small crack, which is the most dangerous defect in the underground pipeline, is hard to detect by conventional system. In this paper, a circumferential magnetic flux leakage-type non-destructive testing is adopted to detect axial cracks. Because the measured signal contains the size and shape information simultaneously, it is necessary to decompose the size and shapes of cracks for the maintenance of underground pipelines. This paper focused on the decomposing method of the sizing and shaping of the axial cracks using measured defect signals. Estimated shapes in this paper agreed well with measuring ones.