Unsaturated Magnetization Stress Detection Technology for Oil and Gas Pipelines
Stress concentration is a key cause for damage and failure of in-service oil and gas pipelines,lay-ing a huge hidden danger for the safety of energy transportation.In this paper,a new method for stress detection in unsaturated magnetized pipelines was proposed.The stress detection mechanism of unsaturated magnetized oil and gas pipelines was analyzed,and an equivalent magnetic circuit model for stress detection was derived.The influ-ence of shielding layer on stress response signals was investigated using finite element method;and tensile stress de-tection tests were conducted on X52 pipeline steel test specimens in the range of 0-140 MPa to verify the sensing a-bility of the unsaturated magnetization detection probe on the stress state of the test specimens.The research results show that as the length of the magnetic shielding layer increases,the signal distortion degree continues to increase,but the gradient value decreases.As the thickness of the magnetic shielding layer increases,the signal distortion degree first increases and then decreases.The tensile stress shows a linear variation trend of negative correlation with the response signal,and the sensitivity of the developed detection probe for the perception of stress state rea-ches 18.48 mV/MPa.The research results provide reference for the development of online detection probe and e-quipment for pipeline stress concentration.
oil and gas pipelinestress detectionunsaturated magnetizationequivalent magnetic circuitshielding
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