Simulation Research Of The Influence Of Detection State On Steel Pipe Circumferential MFL

As an important transportation and supporting material, steel pipe is widely used in petrochemical industry and infrastructure construction. With the rapid development of modem industry, the quantity demanded of steel pipe increased quickly and the client made more application for the quality of steel pipes. According to the American Petroleum Association(API)and China’s national standard requirements,all steel pipe before the factory must be 100% quality inspection. At present, there are many kinds of methods to detect the steel pipe,the common methods are Eddy current inspection, Ultrasonic inspection and Magnetic flux leakage inspection. Magnetic particle inspection,In addition,there are PT、RT、MT. These detection methods, from the detection speed and detection costs on the comprehensive consideration, each have their own advantages and disadvantages. Magnetic flux leakage testing method (MFL) as an effective detection method can effectively detect the internal and external defects in steel pipe,and the specimen surface requirement is low,without coupling agent, the detection process has been widely used in various kinds of ferromagnetic materials,online quality detection is especially suitable for slender ferromagnetic components, such as steel pipe.Based on the electromagnetic fundamental theorem and Maxwell equation, the paper discusses the basic principles of speed effect on the high-speed magnetic flux leakage testing.In the system modeling, the paper introduces Ansoft Maxwell software. During the transient simulation, the paper divided simulation into geometric modeling, material selection, exciting loading,boundary condition choosing, dynamic simulation realize, meshing and post-processing analysis several steps to build the steel pipe circumferential magnetic flux leakage model, and analyzed the influence of the magnetic flux leakage testing to steel pipe caused by factors like steering, rotational speed, wall thickness using stimulation.When the speed did not change, just change the direction of rotation of the steel tube,will not only influence the eddy size is detected,but also affect the distribution of eddy current direction, thereby affecting the consistency of the circumferential MFL inspection assessment, the actual testing process, should try to ensure the consistency of the direction of rotation; Setting the different rotating speed of the steel tube, the size of the circumferential eddy is not the same, the greater the speed, the greater the detection sensitivity of magnetic flux leakage testing, the stronger the ability to detect the smallest defect; Similarly, different steel (i.e. different wall thickness) in the same magnetic field magnetization effect is different,steel tube wall is thicker, the magnetization effect is poor, the detection sensitivity is low,namely the ability to detect defects is weak. Therefore, in the actual detection process, we need to take into account the three factors of the steel pipe circumferential magnetic flux leakage detection, in order to achieve the best detection effect, to ensure the quality of the product, for the product escort.