Design Of Detecting Device For Metal Pipe Inner Diameter And Magnetic Permeability

In recent years,due to the increasingly wide application of petroleum products and the unparalleled advantages of pipeline transportation compared with other modes of transportation,the oil and gas pipeline in our country had made leaps and bounds.With the rapid development of oil and gas pipelines,the corresponding pipeline damage due to natural or man-made factors and the aging of the pipelines were also increasing.Therefore,the research and development of pipeline quality assessment related technologies was imminent.The design of metal pipe inner diameter and magnetic permeability testing device was detecting the pipe properties such as the inner diameter and magnetic permeability of the metal pipe and providing the data support for the subsequent pipeline quality assessment.In this thesis,based on the eddy current testing theory,the design and verification of the device were completed,and the design of the hardware circuit and the related inversion algorithm was completed.Finally,the pipe inner diameter and magnetic permeability were accurately inverted.Firstly,this thesis described the theory of the eddy current testing briefly,and the detection theory of the inner diameter and magnetic permeability of the metal pipe was expounds and analyzes.The metal pipe inner diameter and magnetic permeability detection model was established,the frequency of the excitation signal and the distance between the coils was analyzed and selected.Then the process of establishing the three-dimensional model of metal pipe inner diameter and magnetic permeability detection device and detection environment was introduced,and the influence of defects in the pipe,device detection speed and device eccentricity on the test results of the device was analyzed.The inversion database of the inner diameter and magnetic permeability of the metal pipe was established with ANSYS.Nextly,in the actual development of the detection device for the inner diameter and magnetic permeability of metal pipes,combined with theoretical and measured data,the instrument’s excitation signal and the received signal were processed,and the received signal was picked up and processed by DSP and FPGA-based digital signal processing accurately calculates the phase difference between the transmitted signal and the received signal.Finally,the extreme learning machine algorithm and the least squares support vector machinealgorithm were introduced and implemented in MATLAB.With the inversion database and verification database,according to two calculations comparison of metal pipes’ inner diameter and magnetic permeability value obtained and the inversion algorithm was selected.The feasibility of the device and the accuracy of the measurement were verified by the debugging of the device and the related measurement results.The actual measurement of the metal pipe by the device was used to verify the effect of the device on the pipe inner diameter measurement reached the design requirements.