Research On Deformation Caused By Interference Contact And Stress Analysis Of Cup On Petroleum Pipe Inspection Gauge

Pipeline inspection gauge(PIG)is one of the most significant supporting gauges in the field of oil-gas storage and transportation,which undertakes the important task of cleaning and detecting petroleum pipeline.During pigging process,the cup and sealing disc are used to isolate the fluid and clean the pipe wall.The friction contact between the cup and wall directly affects the working efficiency of the PIG.Therefore,the analysis of the deformation and stress distribution of the cup and sealing disc in the process of friction contact with the pipe can provide theoretical guidance for pigging operation and the design of PIG.In order to measure the deformation of the cup accurately,this paper measured the deformation of the cup based on reverse measurement.In addition,3D FE model of cup and sealing disc running in the straight pipe and tee retaining strip were established to study the deformation and stress distribution.The main research contents are as follows:(1)According to the pigging principle of PIG,the force analysis of the cup when running in the pipe was analyzed.The deformation of the cup was divided into circumferential deformation and axial deformation.The 3D point cloud date before and after deformation of the cup were obtained by 3D laser scanner.After the boundary circle fitting and comparison analysis of the obtained point cloud date,the circumferential deformation and axial deformation of the cup can be obtained with the interference of 1.15%,2.14%,3.14% and 4.16%,which solves the problem that the deformation of the cup in pipe can’t be measured at present.(2)The 3D FE model of the cup when running in the straight pipe with the interference of 1.15%,2.14%,3.14%,and 4.16% were established respectively.The explicit dynamic solver was used for simulation,and the circumferential deformation and axial deformation of the cup with the above interference were obtained.The rationality of the 3D FE model was verified by comparing the experimental value of reverse measurement with calculated value of simulation.At the same time,a new FE model verification method was proposed in the field of pigging.(3)The 3D FE model of cup and sealing disc when running in the straight pipe and tee retaining strip with eight interferences were established respectively.The cleaning ability and anti-blocking ability of the cup and sealing disc were comprehensively analyzed from two aspects of deformation and equivalent stress.In the process of analyzing the operation of the cup and sealing disc in the tee retaining strip,the theory of “height difference” was proposed to analyze the deformation of the cup and sealing disc.Through analysis,it is found that the cleaning ability of the sealing disc is better than cup,while the anti-blocking ability of cup is stronger than sealing disc.Whether it is the cup or the sealing disc,the blocking risk at the junction of tee retaining strip and the straight pipe is greater.In the straight pipe,the interference of the cup should be kept between 3.14%-6.26%,and that of the straight plate should be kept between 4.16%-5.20%.If there are many tees in petroleum pipeline,the interference of the cup should be less than5.20%,and that of the straight plate should be kept around 4.16%.