The Research Of Defect Detecting Technology Of Pipe Head

Magnetic Flux Leakage (MFL) detecting technology is widely used for its high speed, high sensitivity and low requirement for surfacing cleanness. Because the equipment is not effective for detecting defects of pipe head, a large blind zone lies in the pipe head. The traditional magnetic particle testing (MT) technology has the disadvantage of slow speed, narrow range and easy influence by man's activity; so that it is not available for testing a large mount of pipe heads.In this paper we establish a two dimensional static model by ANSYS software, analyze the lines of magnetic induction of defects in the model, and find out a high-speed method for detecting the defects of pipe head.In the paper we firstly introduce the mechanism of MFL detecting, of which the formation and extraction of MFL are the key points. Then we discuss how the factors including mode of magnetization, shape and size of defect, materials of sensor, Lift-off value impact the defect detecting. We mainly analyze the reason of formation of pipe head's detecting blind zone during the detecting process and the impact of scattering of magnetic field lines. By introducing the thought of FEA (finite element analysis) and ANSYS software, we model and solve the defect detecting problem, and demonstrate the impact of lead tube to solve the problem of scattering and disturbance of magnetic field lines and eliminate the blind zone of detecting, by discussing the two different distributions of magnetic field lines whether lead tube is attached to pipe head or not.the paper we put emphasis on modular components of defect detecting system for pipe end, make a detailed explanation of crucial parts which includes detecting device, circuit of main signal capturing and process, HY6070C A/D DAQ (Data-Acquisition Boards) and intelligent detecting of computer system. We also make a discussion of virtual -drive of system, and application of detecting database which has a friendly user interface and overall functions to meet the operation requirement.