Oil And Gas Pipeline Leakage Finite Element Analysis Of The Magnetic Detection Signal Processing

With the widespread application and fast development of gas and oil pipeline networks, the pipeline inspection technology has been used more extensively. Over the years, many different non-destructive testing (NDT) techniques have been investigated for evaluating the condition of pipelines. The magnetic flux leakage (MFL) method can be used to measure the defects, which is the most effective for defects monitoring.This paper first introduce pipeline MFL method research situationanf of domestic, and give a brief introduction to the basic principle of MFL, then introduce the common sensors that are used in MFL, because MFL testing equipment walks slowly and complex work environment, so Hall sensors and excitation coils is shoseing in NDT of oil and gas pipelines, and achieved good results.Introduceing the common MFL model, including experimental model, analytical model and numerical model, and analyses the advantages and disadvantages of the models .And learn of the MFL magnetic dipole method. This dissertation researchs the magnetic dipole theory and applied it to analyze three kinds of common defects.Introducing the finite element analysis (FEA) theory and modeling about the MFL. Firstly introduce the theoretical of Maxwell equations and the problem of nonlinear magnetic control equation. Then use ANSYS simulation analysis the MFL. For the 2D FEA mode set different lift-off value and different size of the flaw, and set in and out defects, inord to learn about the distribution characteristics of MFL signals. The 3D FEA mode would be measured by the axial the radial and the circumferential components of the MFL.The MFL signal is usually contaminated by various noise sources.we propose that the MFL signal extract using the empirical mode decomposition (EMD) in order to get nice SNR. Introduce EMD method. Then use the EMD to processing the practical MFL signals.The results show that the EMD is an efficient method for the MFL singals.