Study On Magnetic Flux Leakage Testing And Typical Defect Recognition Of Forging Pipe Of Oil Pipeline

Petroleum and gas pipeline failure will result in heavy casualties, environmental pollution and other catastrophic accidents. In order to ensure the safety and reliability of pipeline operation, regular nondestructive detection of the pipes has a very important significance. By comparing the pipe nondestructive methods, this paper selects magnetic flux leakage detection technology to detect the pipeline. When detecting the pipelines, the magnetizing devices magnetize the detected pipeline, and the ferromagnetic material pipe fittings such as weld pipe, partner, flange, and tee can also produce leakage magnetic field, which will affect the pipeline defect detection and estimate the location of defects. These problems will bring unnecessary troubles for the pipeline detection, in order to address this problem, this paper will study pipe fittings and defects leakage magnetic field from the following three aspects.Firstly, based on the basic principle of pipeline magnetic flux leakage detection and the factors affecting pipeline magnetic flux leakage detecting, design and optimize the magnetic circuit of the magnetic flux leakage detector. The researched pipeline is X52steel tubes straight seam steel pipe, specifications is0377mm×7mm. From optimizing the magnetic circuit, to get specific parameters of the detection mechanism, which meet the measured pipeline magnetization testing requirements.Secondly, based on the ANSYS finite element analysis theory, using three-dimensional finite element dynamic analysis model to study the leakage magnetic field distribution of the pipeline defects (a single defect, adjacent defects), and the pipe fittings. By comparing the leakage magnetic field of magnetic flux density distribution, obtain the characteristic parameters to distinguish pipeline defects and the pipe fittings leakage magnetic field. These studies can lay the foundation for the post-processing of pipeline defects.Finally, through the analysis of leakage magnetic field of magnetic flux density distribution, the relationships between the size of defects and the flux density component peak, peak spacing is obtained. And by using the SY/T6151-1995standard, the residual strength of pipeline containing defects is evaluated. On residual strength did not meet the requirements of pipeline safe operation of the corrosion defect area some repair measures are put forward, to ensure the reliable operation of the pipeline. In summary, through detecting and analyzing magnetic field of the pipe fittings and pipe defects, getting the characteristic parameters to distinguish these leakage magnetic field. And we also identified the pipeline defect size. These play a guiding significance in engineering for the pipeline magnetic flux leakage testing.