Research On The Experiment System Of Electro-Magnetic Ultrasonic In Pipelines' Cracks Detection

Quality inspection of pipeline plays an important role in the security of pipeline transportation. At present, in the main method of pipeline non-destructive detection, electro-magnetic ultrasonic inspection is emerging. Electro-magnetic ultrasonic inspection has many advantages such as untouched, dispense with couplant, and dispense with pretreatment. It has application prospects unparalleled in the field of non-destructive detection.This paper researches on detecting cracks of metal pipeline with electro-magnetic ultrasonic inspection technique. Key steps including the design of experiment system, which could realize exciting and receiving of ultrasonic using electro-magnetic technique. Build the environment for experiment to accomplish installation and debugging of experiment system. Data acquisition and analysis, which could make inspecting and locating cracks of pipeline come ture.This paper introduces the detection principle of the system, analyses scopes of application of all kinds of wave mode, designs electro-magnetic ultrasonic transducers separately based on the pipe thickness, the drive circuit, signal processing circuit and software of system. This paper also analyses outcomes of experiement. The design of transducers could excite and receive Lamb ultrasonic. Hardware design including exciting module based on the seires of EPM1270 CPLD and receiving module. Sofeware design including timing control program based on CPLD and MATLAB algorithm program. During the experiment, pipeline which is scale marked with cracks for the testing is made firstly. Then install the system to excite and receive the signal of electro-magnetic ultrasonic. Process the data with MATLAB algorithm program. Tell the axial direction of crack in the pipe wall by the principle of decay of receive signal's value. Rotate two transducers in radial direction at one time for acquiring the signal and make curve graph for every group, tell the radial direction of crack by minimal value which is sharply shifted. By compared with the actual crack position and numbers of experiments, this method can be validated the feasibility.