Research Of Tri-Axial Pipeline Magnetic Flux Leakage In-line Inspection Technology

Pipeline has been increasingly used to the transportation of the oil, natural gas and other energy source as one of the main methods of all kinds of energy transport nowadays, especially for the advantages of economy, safety and efficacy etc. With the large area of pipeline laying and operation time extension, the situation that the energy transportation was influenced because of the pipeline problems also occur frequently. In order to guarantee the pipeline for oil and natural gas and other energy transport security, the pipeline inspection is necessary. At present, pipeline magnetic flux leakage (MFL) in-line inspection technology is widely used in pipeline inspection. After years of research improved and the combination of the practical application, the technology in pipeline inspection has been more perfect. But with the rapid development of the society, the oil and natural gas pipeline inspection level requirements are also getting higher and higher. So a higher level pipeline inspection technology is badly needed.This task is aimed at the pipeline in-line inspection technology. And with the method of tri-axial pipeline MFL in-line inspection advanced, the tri-axial pipeline MFL in-line inspection technology is studied. Applying ANSYS simulation software and finite element analyse method to build the simulation model of pipeline tri-axial MFL in-line inspection to perform 3-D simulation analysis. Through the selection of defect size change, the defect leakage magnetic field simulation of pipeline tri-axial MFL in-line inspection model with defect size parameters change is performed. The three components of leakage magnetic field axial, radial and circumferential can be achieved, and the pipeline defects' existence and the effect of the changes of defect size, defect size parameters change and the defect position and lift-off value on leakage magnetic field can be estimated by the three components' graph and the data obtained from simulation. The analysis of the pipeline defect leakage magnetic field circumference MFL signals is the point.Through ANSYS simulation and the results comparison, it is obtained that the pipeline defects' existence judgment, the effect of the changes of defect size parameters, the defect position and lift-off value on leakage magnetic field, circumferential MFL signals in the axial defects leakage magnetic field and the effect of defect size parameters, the defect position and lift-off value variations on the defects leakage magnetic field circumferential MFL signals. Comprehensively analyzing MFL signals of defects leakage magnetic field, the relationship of defects characterization and MFL signals is proved, and the level of traditional pipeline MFL in-line inspection is improved.