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Research on MFL PIG Design for the Inspection of Underground Gas Pipeline  

Park, Sang-Ho (Department of Electrical Engineering, Korea Maritime University)
Park, Gwan-Soo (Department of Electrical Engineering, Korea Maritime University)
Publication Information
Journal of the Korean Society for Nondestructive Testing / v.22, no.2, 2002 , pp. 177-186 More about this Journal
Abstract
This paper describes the magnetic flux leakage(MFL) type non-destructive testing(NDT) system to detect the 3D defects in underground gas pipe. Magnetic systems with permanent magnets and yokes are analyzed by 3D non-lineal finite element method(FEM) with optimum design. In case of under-saturation of gas pipe, sensing signals are too weak to detect. In case of over-saturation, the changes of the sensing signals are too low to detect the defects sensitively. So, the operating points of the magnetic system are optimized to increase the changes of the MFL signals. The effects of the depth and size of the defects on the sensing signals are analyzed to define the range and resolution of the MFL sensors. To increase the sensor's sensitivity, the back-yoke sensors are introduced and tested.
Keywords
MFL(magnetic flux leakage); MFL PIG; operating point; FEM(finte element analysis);
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