SIGNAL PROCESSING OF MAGNETIC FLUX LEAKAGE SURFACE FLAW INSPECT IN PIPELINE STEEL

摘要

The magnetic flux leakage (MFL) method has established itself as the most widely used in-line inspection technique for the evaluation of pipelines. The MFL signal is usually contaminated by various noise sources This paper presents the empirical mode decomposition(EMD) for enhancing signal-to-noise ratio. Experiments are conducted on the pipeline steel samples with different depth artificial defects. The MFL signal is decomposed into several intrinsic mode functions by EMD. Some modes are selected to reconstruct a new signal considering their frequencies and energy. The reconstructed signal has a better signal-to-noise ration. The results show that EMD technology is efficient in eliminating noise in the MFL signal.