Detection Method of Leakage Holes in Long-Distance Natural Gas Pipelines Based on Permanent Magnetic Perturbation

A detection method based on permanent magnetic perturbation is proposed to solve the problem of leakage hole detection in long-distance natural gas pipelines. The spatial field changes caused by defects are analyzed by combining the magnetic perturbation equation with Faraday's law of electromagnetic induction. Simulation calculation of the coil cascade flux and the magnetic induction intensity under the permanent magnet is carried out by the finite element method, and the change rule of magnetic perturbation in the permanent magnet is further analyzed. The permanent magnetic perturbation detection system of pipeline leakage holes is designed and developed, and the experimental platform of leakage hole detection is built. The experiments verify the detection ability of permanent magnetic perturbation technology on hole defects. The results show that, when the sensor is located directly above the defects, the magnetic perturbation generated is the most intense, and the detection voltage signal is the largest; with the increase of the hole diameter, the amplitude of the detection voltage signal gradually increases. The method provides a reference for further engineering applications of pipeline leakage hole detection.