Research On Pipeline Crack Detection And Recognition Method Based On Pipeline Magnetic Flux Leakage Internal Detection

The world's most important fossil energy oil and natural gas transportation method still relies on ferromagnetic pipelines.Factors such as environment and age will cause corrosion defects,rectangular defects,pipe explosions,etc.of the pipeline.Once an accident occurs,it will not only cause significant national economic losses,but also cause serious social environmental pollution.The pipeline magnetic flux leakage internal detection has the advantages of precision,convenience,high efficiency and safety,and it is an important means to ensure the safe operation of the pipeline at present.The geometric size of the pipeline defect is related to the service capability of the pipeline.Establishing an accurate description between the geometric size of the pipeline defect and the corresponding leakage magnetic field is crucial to the identification of the pipeline defect.In this paper,for the mathematical relationship between the geometric size of the defect and the magnetic leakage field in the internal magnetic flux leakage detection,based on the internal magnetic leakage detection technology of the pipeline,the magnetic field of the rectangular defect is analyzed according to the magnetic dipole theory,and the magnetic field of the rectangular defect of different pipelines is studied.Characteristics,to explore the mathematical relationship between the leakage magnetic field of the inner and outer rectangular defects of the pipeline and the size of the defect,to establish a three-dimensional magnetic dipole model of the inner and outer rectangular defects of the pipeline,and to use the software to solve the inner and outer rectangular defects of different sizes of the pipeline Leakage magnetic field model,to study the spatial distribution of inner and outer wall defects of pipes with different wall thickness and the spatial distribution of inner and outer wall defects of the same geometric size.Experiments were carried out using pipeline magnetic flux leakage internal inspection equipment to detect rectangular defects of different widths and depths.The results obtained by analyzing model calculation data and experimental data were compared with the model and engineering inspection results.The distribution characteristics of the leakage magnetic field verify the accuracy of the three-dimensional magnetic dipole model of rectangular flaw leakage magnetic field.The results show that the amplitude of the leakage magnetic field of the inner wall of the pipeline of the same size based on the internal magnetic flux leakage detection of the pipeline is larger than the leakage magnetic field of the outer wall of the pipeline in the triaxial direction.Within a certain range,as the wall thickness of the pipeline increases,the outer wall of the pipeline wall The shielding amount of the defect leakage magnetic field is gradually increasing;a series of laws obtained by the three-dimensional magnetic leakage dipole model of the defect leakage magnetic field of the inner and outer walls of the pipeline are consistent with the experimental results and the laws obtained by engineering experience,which verifies that the proposed model describes the pipeline leakage magnetic field The effectiveness of the spatial distribution;the model calculation data and the experimental data have a linear proportional relationship so that an accurate three-dimensional analytical model of the leakage magnetic field of the inner and outer wall defects of the pipeline based on the internal magnetic flux leakage detection of the pipeline can be established.