Publication: Publication Date: 1 March 2010Testing Method:

Many factors cause degeneration of the measured signal in magnetic flux leakage (MFL). One of these factors is non-uniformity of the magnetic flux inside the sample under test. Uniformity of the magnetic flux results in smoother and more predictable signals from various discontinuity types and also a reduction in the eddy current distortions induced because of the movement of the magnetizing yoke. The goal of this research is to find a near-optimal length for the magnetizing yoke. Toward this end, yokes with different lengths are simulated with the finite element method and the quality of the distribution of the flux lines inside the sample is studied. In this way a criterion for optimization of the length of the yoke is presented. Lest the optimization process deteriorate the discontinuity detection performance, simulating various discontinuities, the sensitivity of the system was studied for three different yoke lengths: optimal length; shorter length; and longer length.

References

Atherton, D.L. and M.G. Daly, “Finite Element Calculation of Magnetic Flux
Leakage Detector Signals,” NDT International, Vol. 20, 1987, pp. 235–238.
Jansen, H.J.M., P.B.J. Van De Camp and M. Geerdink, “Magnetisation as a
Key Parameter of Magnetic Flux Leakage Pigs for Pipeline Inspection,”
Insight, Vol. 36, 1994, pp. 672–677.
Li, Y., G.Y. Tian and S. Ward, “Numerical Simulation on Magnetic Flux
Leakage Evaluation at High Speed,” NDT&E International, Vol. 39, 2006,
pp. 367–373.
Mandal, K. and D.L. Atherton, “A Study of Magnetic Flux-Leakage Signals,”
Journal of Physics D: Applied Physics, Vol. 31, 1998, pp. 3211–3217.
Nestleroth, J.B. and T.A. Bubenik, Magnetic Flux Leakage (MFL) Technology
for Natural Gas Pipeline Inspection, Battelle for the Gas Research
Institute, February 1999.
Park, G.S. and E.S. Park, “Improvement of the Sensor System in Magnetic
Flux Leakage-Type Nondestructive Testing (NDT),” IEEE Transactions on
Magnetics, Vol. 38, 2002, pp. 1277–1280.
Park, G.S. and S.H. Park, “Analysis of the Velocity-Induced Eddy Current
in MFL Type NDT,” IEEE Transactions on Magnetics, Vol. 40, 2004, pp.
663–666.
Tiratsoo, J., Pipeline Pigging and Integrity Technology, third edition,
Beaconsfield, UK, Scientific Surveys, 2003.

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