Dynamic demagnetization experiment on China-Russia Eastern Gas Pipeline

The residual magnetism produced during the construction and inspection of long-distance oil and gas pipelines can cause the magnetic blow of welding arc, which may affect the welding progress and quality of pipelines and even threaten their intrinsic safety. The high residual magnetism of China–Russia Eastern Gas Pipeline Project using largediameter and high-grade pipes brought a greater challenge to the available demagnetization technology and the service ability of demagnetization equipment. For this reason, the permanent magnet demagnetization technology was introduced, and the permanent demagnetization was realized through the dynamic demagnetization tests designed based on the response surface method. In addition, the accuracy of experiment results was verified by the electromagnetic field simulation of pipelines. The results show that the magnetic field intensity of demagnetization equipment is an important factor influencing the demagnetization effect of pipelines. Specifically, the demagnetization rate increases with the demagnetization intensity increasing. However, the operation velocity of demagnetization equipment does not affect the demagnetization effect significantly. The research results could provide a new research direction and idea in terms of the demagnetization technology for pipelines.