Testing Experiments And ANSYS Simulation For Underground Pipelines Based On Non-contact Magnetic Memory Effect

Buried pipes play an extremely important role in national economic operation and people's daily lives,but they face a very serious aging problem,coupled with the complexity of the operating environment,in the event of leakage,explosion,often resulting in huge casualties and economic losses,While bringing serious environmental pollution,has become a major hazard to public safety risks.It is unrealistic to carry out comprehensive excavation testing and often require non-contact detection in the case of non-excavation.Non-contact magnetic memory detection technology it can determine the stress concentration area-the main source of equipment damage development for the buried pipeline on-line non-contact magnetic memory detection provides a theoretical basis.Based on the field test,this paper analyzes and evaluates the buried pipes with different burial depth,internal pressure and material.In the defective position,the magnetic memory signal behaves as follows: the tangential component and the normal component appear to decrease or rise substantially,and the gradient appears to have obvious reciprocating fluctuation.It has an abnormal magnetic memory signal of the pipeline part of the excavation,detection that in the abnormal location will appear leakage,external corrosion,internal corrosion.The finite element simulation and analysis of buried pipelines with different depths and pressures are carried out by simulation software.The transformation rules of magnetic memory signals at different depths and different pressures are obtained.When the residual stress is not taken into account,The peak-to-peak intensity of the tangential magnetic field and the peak-to-peak intensity of the normal magnetic field are decreasing.As the buried depth increases,the peak pressure of the buried magnetic field decreases The effect of the contact magnetic memory signal is much less than the depth of the buried.When the welding residual stress is considered,the multi-field coupling simulation of the weld defect is further carried out.As a result,it can be seen that,compared with the absence of defects,both the buried part of the tube,the tube,the pipe,The peak-to-peak intensity of the tangential magnetic field and the peak-to-peak value of the normal magnetic field are increased,and the normal magnetic field intensity signal on the tube and tube is reversed.Finally,the finite element simulation results are compared with the experimental results of magnetic memory test.In the defective position,the peak-to-peak intensity of the tangential magnetic field and the normal magnetic field are increasing,and the gradient is changed greatly.The simulated magnetic memory signal And to provide the basic theoretical research and method basis for the practical engineering application of the non-contact magnetic memory detection and evaluation of buried pipeline.