A Study on the Signal Correction for Multiple Defects in MFL Type Nondestructive Testing System
Dept. of Electrical and Computer Engineering, Pusan National University, Busan 46241, Korea(Received 15 January 2016, Received in final form 22 February 2016, Accepted 23 February 2016)MFL (Magnetic flux leakage) type nondestructive testing has been used for inspection of underground gas pipelines to find metaldefects by detecting magnetic leakage signal. Because the underground gas pipeline is exposed by environment such as high pressurewith great humidity, external defects are easily formed on the surface of pipelines and they are being grouped respectively. Theseadjacent defects cause the signal distortion of leakage flux so that it is hard to estimate the shape information of defects. In this paper,we performed to study of the signal distortion and compensating method for multiple defects in MFL type nondestructive testingsystem by using 3D FEM simulation. This paper proposes the basic algorithm of defect signal analysis on multiple defects on thesurface of 30 inch diameter pipeline.Keywords: magnetic flux leakage testing, nondestructive testing, pipeline, multiple defects, finite elements method