LAUSR

Abstract This paper demonstrates a method of measuring the permeability of a pipe based on the magnetic shielding effect via simulations and experiments. Short pipe specimens are directly cut from a long industrial pipe instead of machining the pipe into strip, rod, or ring specimens. During measurement, the pipe specimen immersed in the geomagnetic fields rotates around a vertical axis and the magnetic fields inside are simultaneously recorded. It is found that original magnetizations can induce magnetic bias inside the pipe, which can be calculated and removed by using the recorded fields as a function of rotation angle. The magnetic fields without bias are used to calculate the shielding factor and then uniquely determine the pipe permeability based on the pipe shielding model. Since employing a pipe itself as the specimen can avoid additional magnetization generated during re-manufacturing, the measured permeabilities by the proposed method can be used as permeability samples and references for an on-site pipeline during magnetic abnormity inspections.