Three-axis magnetic flux leakage in-line inspection simulation based on finite-element analysis

With the increasing of pipelines, the corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage (MFL) in-line inspection system is introduced firstly. Besides, a mathematic model of the system according to ampere circuit rule, flux continuity theorem, and column coordinate transform is built. And the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and designe the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time. So we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhance the detection ability to different types of defects but also improve the precision and reliability of the inspection system.