Saturation/unsaturated magnetic field analysis and unit structure optimization of small-diameter pipeline

In small-diameter pipelines, where space is constrained, achieving a consistent magnetic flux is vital for enhancing the sensitivity and reliability of defect detection. This aspect is particularly crucial for applications involving small-diameter pipelines. The primary objective of this study is to identify the optimal dimensional parameters of the excitation unit for 4-inch small-diameter magnetic flux leakage (MFL) tools. The Finite Element Method (FEM) was employed to analyze the evolution patterns of the magnetic field at defect sites across various operational parameters. Additionally, the relationships between these influencing factors within the magnetic circuit and the induced magnetic field in the pipe wall were established. It is of great significance to promote the development of safety detection technology for small-diameter pipelines in oil field gathering and transportation.