Investigating the Characteristic of Weak Magnetic Stress Internal Detection Signals of Long-Distance Oil and Gas Pipeline Under Demagnetization Effect

Studies show that the demagnetization effect of the pipeline wall affects the detection accuracy and detection range of the pipelines’ weak magnetic stress internal detection (WMSID). The present study deals with mathematical modeling of the WMSID under the demagnetization effect. Moreover, the interference characteristics of the demagnetization effect on the weak magnetic signal (WMS) are analytically calculated and the transfer features of WMSs are studied. Obtained results show that in the transmission medium, the demagnetization effect produces an interfering magnetic field. It is found that performing the demagnetization effect calculation can reduce the calculation error of the mathematical model by 27.6%. Moreover, the demagnetization impact in the pipeline wall material complicates detecting the stress concentration zone (SCZ) on the pipeline’s outer wall. Normal component WMS has high stability in the pipeline wall material so that it is an appropriate choice for detecting the SCZ on the pipeline’s outer wall. Finally, the BiHill function is introduced to fit the excitation curve of the WMS.