Effect of Magnetic Excitation Intensity on Stress Recognition and Quantitative Evaluation in Ferromagnetic Pipelines

Stress detection is an effective way to prevent pipeline failure, but stress recognition alone can hardly meet the safety and maintenance requirements of pipelines. Rather, improving the accuracy of stress detection and quantification has long been a top priority in the engineering sector. In the present study, stress detection models for pipelines were developed under varying magnetic excitation intensities, and the influence of a changing magnetic excitation field on stress recognition capacity was investigated. The variation law of the accuracy of stress detection under different excitation intensities was determined and validated experimentally. The results showed that at an excitation intensity of 2.5 of kA/m, the polarity of weak magnetic signals flipped when used to detect stress below 40 MPa, making the stress quantification difficult. The stress recognition capacity was the greatest under an excitation intensity of 7.5 kA/m for the stress below 40 MPa and the greatest under an excitation intensity of 5 kA/m for the stress of 40–160 MPa. Our research findings offer theoretical clues for choosing an appropriate excitation intensity for stress detection. The findings provide technical support for pipeline integrity assessment and risk warning, playing an important role in ensuring the safe operation of oil and gas transportation systems.