Research On Computer-Aided Radiographic Testing Technology For Pressure Storage Tanks

The pressure storage tank is a closed container used to store a certain medium.Due to the particularity of its use,it is placed under high pressure,high temperature,corrosion,and other environmental conditions all year round.Because most of the storage is flammable and explosive or contains highly toxic harmful substances,the safety of the pressure storage tank is the top priority.Welding is the main processing method of the pressure storage tank.Welding quality is one of the main factors affecting the manufacturing quality and performance of pressure storage tanks.As one of the common methods of welding quality inspection,radiographic testing plays an important role in the evaluation of the safety performance of pressure storage tanks.Therefore,efficient and accurate radiographic testing and result evaluation of pressure storage tanks is a major focus to ensure the safe operation of pressure storage tanks.In this thesis,the influence of defects on the performance of pressure storage tanks and the means of computer-aided ray detection technology is studied by computer finite element simulation and programming technology.The influence of defects on the safety performance of pressure storage tanks is analyzed and two computer-aided ray detection systems are designed.The main research contents are as follows :(1)The regulations,main methods and evaluation specifications of weld inspection for pressure storage tanks are summarized.The theory of fracture mechanics is expounded,and the concepts and calculation methods of crack classification,stress intensity factor,crack propagation and fatigue life are analyzed.The definition and calculation methods of the three pattern recognition methods used in this thesis are sorted out.(2)Through ANSYS software,the stress intensity factor calculation and fatigue life analysis of pressure storage tanks with crack defects are carried out,and the stress analysis and comparison of elliptical pits with different ratios of short and long axes on pressure storage tanks are carried out.The influence of weld crack defects on the stress distribution and fatigue life of pressure storage tanks is obtained.(3)Based on the principle of radiographic inspection,a computer-aided inspection process preparation system was designed through Python programming to obtain the data required for the optimized radiographic inspection process and automatically generate radiographic inspection process files;the operation process of the computer-aided inspection process preparation system programmed in Python was given as an example of the actual inspection requirements for in-use pressure storage tanks.(4)Through image retrieval technology and eigenvalue extraction method,adaptive filtering and adaptive histogram equalization are selected as the methods of image denoising and image enhancement respectively through experimental comparison.Hu invariant moment and color moment are used to extract the eigenvalues of different defects respectively,and the eigenvalue library of the image library is established.The computer-aided radiographic testing and evaluation system is designed in a MATLAB environment,and the detailed structure and operation flow of the evaluation system are given.By simulating the crack defects of the stress tank welded welding seam,the effect of the crack on the stress distribution and fatigue life of the crack on the stress tank,and provide a certain reference for the design and use of the defective stress storage tank;according to the principle of radio detection principle The image processing technology has designed a computer-aided ray detection process compilation system and film evaluation system,which effectively improves the efficiency and accuracy of the ray detection of pressure storage tanks,and provides staff with great convenience.