| After nearly fifty years of development,the natural gas pipe network in sichuan and chongqing areas has formed a ring pipe network structure with variable pipe diameters and multiple multiple lines,which has the characteristics of multiple gas sources and users.Due to the time of the construction of gas pipeline is differ,uneven pressure ability,at the same time due to the change of gas source and transmission distance is growing,the pipe network pressure fluctuations are frequent,produce alternating load will be passed to the pipe itself is relatively weak,lead to pipeline coating spalling,fatigue failure and ductile fracture events,eventually cause pipeline failure.Therefore,it is of great significance to study the influence of pressure fluctuation of natural gas pipeline network on pipelines in sichuan and chongqing areas.Based on the part of each regional gas pipeline as the research object,from the pipe material mechanical performance test,dynamic response of pipeline,the fatigue life and fatigue crack propagation study:(1)on the gas pipeline pressure fluctuation analysis,the main reason for the collect of instantaneous pressure data types of piping material,production and parameters of pipeline pigging are basic data such as records.Through research and analysis,three kinds of target pipe materials and five target pipes were determined,and instantaneous pressure data of the target pipe in the past five years were collected,and the pressure fluctuation range and frequency of the target pipe were statistically analyzed by rain flow counting statistical method.(2)Adina finite element software was selected to establish a model of gas pipeline(spiral welded pipe,elbow pipe and tee)without weld defects under the action of periodic pressure fluctuation;The finite element model of target pipeline containing weld defects was established and the influence of periodic pressure fluctuation on fatigue life of pipeline was analyzed theoretically.According to the data collected at the same time,combined with a pipeline gas even head project,selecting the parent metal and weld in section of pipeline of uniaxial tensile test,high cycle fatigue test,analysis of pipes,mechanical properties and fatigue life test results with the standard found basic mechanics performance parameters of pipes,in comparison with the finite element model,the calculation results by periodic pressure fluctuations affect the outcome of pipeline.(3)establish the finite element model of pigging pushing ball in the pipeline,study and analyze the ultimate load of pigging pushing ball,determine the differential pressure of pigging pushing ball,and verify the model with an accident case of a pipeline pigging bursting during pressure test.Therefore,the influence of pressure fluctuation on gas transmission pipeline is determined,and the control measures of pressure fluctuation in gas transmission pipeline are proposed.This article through to each region of natural gas pipe network pressure fluctuations on the impact study,confinn that the effect of pressure fluctuations of gas pipeline as a result,the control measures are put forward,to prevent failure accidents,to ensure safe and smooth operation of pipeline,put forward each region of the natural gas pipe network of thirty-six key pipeline pigging pushed the ball differential pressure limit value for the pipeline pigging provides reference Suggestions. |
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