Magnetic Flux Leakage (MFL) method is commonly used to test the integrity of ferro-magnetic materials such as natural gas transmission pipelines. The inspection tool comprises of permanent or electromagnets that magnetize the pipe-wall axially and an array of Hall sensors that detect the presence of leakage flux in the vicinity of a corrosion or crack. Noise due the variation in magnetic properties of pipe and sensor lift-off, affect the signals and their subsequent interpretation. Traditionally, MFL inspection probes measure a single component of the leakage flux (generally axial component) to detect structural flaws in the pipe. However, more recently, the industry is moving towards building inspection tools with 3-axis sensors that measure all 3 components of the leakage flux density. This paper presents a novel procedure for combining all three components of the field to enhance the detection probability of smaller defects without increase in the false calls.
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