Finite Element Modelling of Circumferential Magnetic Flux Leakage Inspection in Pipeline

The axial magnetic flux leakage(MFL) inspection tools cannot reliably detect or size axially aligned cracks, such as SCC, longitudinal corrosion, long seam defects, and axially oriented mechanical damage. To focus on this problem, the circumferential MFL inspection tool is introduced. The finite element (FE) model is established by adopting ANSYS software to simulate magnetostatics. The results show that the amount of flux that is diverted out of the pipe depends on the geometry of the defect, the primary variables that affect the flux leakage are the ones that define the volume of the defect. The defect location can significantly affect flux leakage, the magnetic field magnitude arising due to the presence of the defect is immersed in the high field close to the permanent magnets. These results demonstrate the feasibility of detecting narrow axial defects and the practicality of developing a circumferential MFL tool.