Study On The Influence Of External Magnetic Field On The Weak Magnetic Stress Detection Signal

Pipeline transportation is one of the main methods of modern energy transportation.Oil,natural gas and other energy sources are called industrial blood due to their important industrial status.Compared with other modes of transportation,pipeline transport costs,and safety performance has irreplaceable advantages of pipeline buried in the ground all the year round,but the ground environment change,the crustal movement,and the long time operation of the pipeline pipe will cause loss,aging,defects such as stress concentration,and the defects in the process of pipeline operation is difficult to detect,eventually cause safety accidents.At the same time,a large number of stress concentration areas will be generated in the process of pipe making and construction.Some stress concentration areas have reached the critical yield point,leading to sudden accidents after the pipeline is put into operation.Conventional magnetic eddy current nondestructive testing techniques such as magnetic powder leakage and penetration,in such aspects as the defects of pipeline monitoring and accident prevention play an important role,but only found the macroscopic volume defects,could not be on the construction of foundation settlement within the medium pressure welding thermal expansion has not yet been forming factors such as volume defects of effective evaluation of stress concentration area,which is inevitable due to stress damage caused sudden accident.In this paper,a mathematical model of magnetics was established based on the JA theory,and the characteristics of the detection signal in the weak magnetic stress under the action of different external magnetic field intensities were quantitatively studied.The corresponding relationship between the stress concentration area and the weak magnetic signal is calculated and analyzed.Under the action of different external magnetic field intensity,the change characteristics of the three-dimensional weak magnetic signal in the stress concentration area are analyzed;The mathematical model of magnetic inspection in long distance oil and gas pipeline is established,and the magnetic characteristics of stress concentration area under different external magnetic field intensity are systematically studied;The influence law of the external magnetic field on the detection signal in the pipeline weak magnetic field is clarified,which provides a scientific basis for the interpretation and recognition of the detection signalin the pipeline weak magnetic field.In addition,in order to verify the effectiveness of simulation and theory,the variation trend of weak magnetic signal under the change of external magnetic field was designed,and the relationship between stress and magnetism was clarified.At the same time,the influence rule of external magnetic field under the weak magnetic detection environment was determined.