The Research Of Stress Concentration Area Of Pipes Ground Detection Technology Based On Metal Magnetic Memory

Currently, the main mode of transport of oil and gas through the pipeline to achieve,occupies a very important position in the oil industry. In recent years, with the increase inpipeline service time, our country has been largely close to the maximum number of pipes age,accidents, in order to ensure safe use of oil and gas pipelines, need to be testing andmaintenance. Metal magnetic memory technology in the diagnosis of early fatigue and injuryferromagnetic materials with great potential, MMM ferromagnetic material testing equipmentcan detect the position of the stress concentration area. So far, there are no such non-contactmagnetic diagnostic technology and equipment, the cost of providing such non-contactmagnetic diagnostic technology abroad is very high, and the technical implementation of theblockade and monopoly.The metal magnetic memory technology can detect stress concentration area of aferromagnetic material under the effect of the geomagnetic field, to determine the stressconcentration area to the pipe component and its gradient value is detected by the analysismethod of the pipe surface. This paper studies the causes of metal magnetic memorytechnology produces and the detection mechanism. Metal magnetic memory technology can beapplied at a ferromagnetic material, non-contact stress concentration area detection, analysisand detection methods for non-contact detection of their on field stress concentration area offerromagnetic material will be discussed, the use of magnetic dipole its sub-model analysis.Studied the magnetic dipole far-field model, and has been deduced calculated the magneticfield distribution formula far-field magnetic dipole model. According to the magnetic fielddistribution formula far-field magnetic dipole model, its inversion calculation, inversionmethod requires the use of magnetic induction points were calculated the magnetic momentvalue of the magnetic field. Application of this method for buried metal pipe surface magneticfield of ferromagnetic material for analysis, can effectively address the impact of differentheights due to the lift-off brought on detection. Non-contact detection method MMM singleprobe lift-off height because some impact on the test. The stress concentration area equivalentto magnetic iron magnet magnetic material, the use of magnetic intensity meter Menci Themagnetic dipole far-field inversion calculation model, at different distances be detected by calculating the magnetic field magnetic moment value. When calculated using themeasurement results of different heights to give a substantially uniform magnetic momentvalue of the result.Experimental results show that the inversion of magnetic dipole far-field model canaccurately calculate the magnetic moment value of the magnetic field. This analysis methodcan be applied to prove the analysis of ferromagnetic materials magnetic stress concentrationarea, and applied to a non-contact detection of metal magnetic memory.