Research On X-ray Digital Imaging Detection Technology For Steel Pipeline Defects

In the nondestructive testing of industrial pipelines,X-ray detection technology is an important means to detect inner defects of pipeline.It can visually detect potential defects in the welding,so as to facilitate the management and control of welding quality,and its qualitative and quantitative analysis of defects is accurate.X-ray digital imaging is a new nondestructive testing method,which has the advantages of fast detection speed,high detection efficiency,high sensitivity and resolution,wide dynamic range and so on.X-ray digital imaging inspection technology is the development direction of nondestructive testing technology.But the current digital detectors are flat hard screen,which will cause geometric distortion of the defect image in the pipeline inspection.Based on X-ray digital imaging detection technology,the principle and correction method of image distortion of pipeline defects are studied.The main research contents are divided into the following three parts:1.Research on image preprocessing based on X-ray digital image.X-ray digital image processing methods,including noise reduction,image enhancement,edge detection and defect extraction,etc.are studied.The effects of several commonly used image processing algorithms in X-ray digital image processing are analyzed and compared,and a better algorithm is selected to preprocess images obtained by experiments.2.Research on pipeline defect reduction algorithm based on back projection method.In the paper,the traditional X-ray detection technology and X-ray digital detection technology are discussed.Moreover,the distortion mechanism of the defect image is studied.First,the distortion geometric model is established by theoretical analysis to determine the distortion law of the defect image.Secondly,the back calculation relation is deduced,and the pipeline defect reduction algorithm based on back projection method is given,so the pipeline defect reduction software based on X-ray digital image is designed.3.Design experiments to verify the accuracy and feasibility of the algorithm.The X-ray digital imaging experiment includes-the following steps:to preset defects in the test pipeline,determine the relevant process requirements,select advanced DR system to conduct the experiment,obtain clear image of defects,verify the algorithm,discuss and analyze the experimental results,contrast before and after the reduction of defect size and found that the relative error less than 4%,and verify the feasibility and practicability of the algorithm.Based on the mechanism of DR image distortion in pipeline,a geometric distortion model is established and a distortion reduction algorithm is proposed.The application effects of various algorithms such as image noise reduction,image enhancement and image edge detection in X-ray digital image processing are studied,so that a defect reduction algorithm based on MATLAB is designed,and the corresponding GUI(graphical user interface)is established to simulate the algorithm.Through comparison,simulation and experimental verification,it is proved that the proposed image reconstruction algorithm is effective and has high accuracy and feasibility.