Electromagnetic field analysis for outer orientation problems in in-line pipeline inspection

In-line pipeline inspection is one of the most important ways to inspect pipeline safety. It is necessary to locate the corrosion from the ground after the detection is completed. The four-step comprehensive method, which contains course wheel orientation, welding lines modification, outer orientation modification and revolving angle orientation, is proposed in this paper. At the same time, outer orientation modification usually use the way of low-frequency electromagnetic wave to modify the course wheel's count, for improving the precision. This article establishes the outer orientation model, deduces the formula of the magnetic strength in the pipeline, and uses ANSYS software to simulate the model. The simulation not only accords with the experiment, but also shows that different parameters would affect the magnetic strength in the pipeline. It is significant to understand the outer orientation technology with low-frequency electromagnetic waves.