Design Of Magnetic Flux Leakage Testing System For Iron Pipeline And Study On Defects Of Iron Pipeline

Pipeline transportation,as one of the most commonly used transportation modes in the world,has been widely used in social life due to its advantages such as large transportation volume,relatively good transportation safety,high reliability and low price.According to the statistics of relevant research institutions,the domestic pipeline transportation mileage is more than one million kilometers,and the vast majority of oil and gas pipelines are hidden underground.Under the action of the complex environment around the pipeline and the internal fluid transport medium,it is easy to lead to corrosion,perforation,cracks and other defects,which seriously affect the transportation safety of the corresponding pipeline.According to the relevant statistics in recent years,the majority of pipeline leakage accidents occurred in the deep-buried small and mediumsized iron pipelines installed in the 1980 s and 1990 s,while the current magnetic flux leakage detection and acquisition devices are mostly used for defect detection of large iron pipelines.Therefore,this paper mainly aims at different defect detection problems of small and medium-sized iron pipelines.This paper analyzes different detection technologies and different types of pipeline detection carrying devices,summarizes the advantages and disadvantages of various pipeline detection technologies and the characteristics of various pipeline carrying devices,and conducts corresponding research on the detection problems of different defects of small and medium-sized iron pipelines.The specific research of this paper is as follows:Firstly,the basic concept of magnetic field,its formation reason,formation mechanism,magnetic leakage detection principle,magnetic dipole theory and finite element analysis are introduced,which provide theoretical basis for the design and research of magnetic leakage detection system of small and medium-sized iron pipes.Then,in order to solve the defect detection and loading problem of small and medium diameter iron pipelines,the composition of the corresponding system is analyzed by using module analysis method,and the excitation part,magnetic leakage detection part and magnetic accumulation part of the corresponding core part are designed.Then design the hardware and software system of the information acquisition and control part of magnetic leakage.In order to verify the passing performance of the magnetic flux leakage detection carrier,the theoretical analysis of the passing performance of the magnetic flux leakage detection carrier was carried out,and the corresponding passing simulation was carried out by ADAMS to verify its passing performance.In addition to solving the corresponding loading problem of magnetic leakage device,in order to further analyze the defect problem of iron pipeline,the advantages and disadvantages of the commonly used rectangular defect model are analyzed,and the principle and characteristics of pipeline defects are used to classify the defects and summarize their typical characteristics.In addition,COMSOL software is used to analyze the magnetic field distribution of different defects and the influence of different factors on the magnetic field of pipeline defects under the permanent magnet excitation mode,so as to provide help for the classification of defects in the case of magnetic leakage detection and the specific situation of defects in the case of determining the type of defects.Finally,in order to verify the influence of different factors on different defects,experiments were conducted to verify the influence of corrosion layer thickness,crack depth and strike,hole diameter and depth,and deformation height and thickness ratio on magnetic field intensity.