Analysis Of Pipeline Notch Characteristics Based On Metal Magnetic Memory

Pipeline is an important part of oil and gas development and transportation.With the widespread use of oil and gas pipelines,the structural discontinuity and stress concentration caused by notch need to be paid more attention.Metal magnetic memory testing is a relatively new nondestructive testing technology.There is no need to pretreat the measured material,and it can detect the early stress concentration and invisible damage of ferromagnetic materials,which is very suitable for the oil and gas pipeline detection process.This paper takes X70 oil and gas pipeline as the research object,uses numerical simulation method to analyze the magnetic memory signal characteristics of different pipeline notches,and establishes V-notch inversion model.It provides reference for the application of metal magnetic memory in oil and gas pipeline.The main contents and conclusions are as follows:(1)Firstly,the current research status of metal magnetic memory detection is introduced,and the basic characteristics of ferromagnetic materials,magnetic field line distribution in notch region,notch magnetic memory signal characteristics,forcemagnetic coupling model is briefly summarized,and the current mainstream metal magnetic memory detection mechanism is introduced.(2)The influence of notch shape on magnetic memory signal was studied.Based on the above theory,the prefabricated V-shaped,slot and arc-shaped notch pipeline models were established by numerical simulation method,and the force-magnetic coupling simulation analysis was carried out.The law between notch size and magnetic memory signal was summarized,and the magnetic memory signal characteristics of notch with different morphology were analyzed.(3)The V-shaped double notch magnetic memory signal is analyzed.Based on the analysis of V-type single notch,the numerical simulation analysis of the prefabricated Vtype double notch pipeline is carried out to compare and analyze the magnetic memory signals of V-type single notch and double notch,and the influence of the distance between the notch and the size of the notch on the magnetic memory signals of double notch is studied.(4)The V-notch inversion model is established.Based on the above numerical simulation analysis,taking the common V-notch as the research object,by extracting the magnetic memory signal characteristics of 48 groups of V-notch,the BP neural network model was established to realize the dimensional inversion of V-notch.The final results show that the BP neural network model can be used for quantitative inversion analysis of notch size and provide reference for the practical application of magnetic memory detection.