DIPOLAR MAGNETIC FLUX LEAKAGES FOR PIPELINE RECTANGULAR DEFECT CHARACTERIZATION: ANALYTIC APPROACH

Magnetic Flux Leakages (MFL) find its application in non-invasive of Non-Destructive Testing and Evaluation (NDT&E) to detect and characterizeddefect in pipelines made from ferromagnetic materials. Various improvementsof MFL models have been investigated for defect quantification but still couldnot achieve higher precision due to technical errors. We, therefore, proposemodels that minimize the error generated by inverse MFL model for defectquantification. Depth and width polynomial expressions were generated fromthe peak values of the two MFL profile using polyfit function for their errors’evaluation by varying depth at constant width and varying width at a constantdepth. The model gives a prediction of a rectangular defect quantificationbased on dipolar magnetic charge model from the nature of the axial and radialflux leakages profile. The proposed model used analytic expressions tocharacterize the defect from the MFL signal. Among the three axes of the MFLprofile, only radial and axial profiles were used in this paper to quantify thedefect. The model improved the error margin and proved that the radial MFLprofile is best for the estimation of defect length along the scan axis directionwith nearly zero percent error while the axial MFL profile provides best resultsfor the evaluation of width and depth with 2.20% and 2.18%as maximumpercentage error. The proposed Radial and axial leakage profile analyticalmodels are simple and can be used for reconstruction of defect in inverse MFLproblem.