The interaction of multiple magnetic circuits in magnetic flux leakage (MFL) inspection

In this paper, a multi-magnetizer comprise of three units was introduced, of this multi-magnetizer, permanent magnet, poke, brush, and pipeline form a closed magnetic circuit in each unit, and each unite can be adjusted relative angle to meet the requirement for detection of pipes with different size. The investigation focuses on the interaction due to the introduction of multiple magnetic circuits in magnetic flux leakage (MFL) inspection. Magnetic intensity and permeability of ferromagnetic materials along with characteristics of signal generated by defect were analyzed. Alteration of the intensity and distribution of magnetic field leakage caused by addition of multiple magnetic circuit were investigated via theoretical analysis and finite-element method (FEM) combined with the actual MFL test. Following this, a specially designed experimental platform, in which multi-magnetizer within the range of 1-3 circuit, was employed to... verify the probability of actual defect inspection and interaction of units. Preliminary results indicate that the MFL technique can achieve effective defect inspection; Characteristics of signal generated by pipeline defect is similar with plate; Because the addition of multiple magnetic circuit, Magnetization intensity and permeability were enhanced whether mediate or sideways, the increasing rate of mediate is greater than sideways, and two sideways have the same increasing rate.