| Under the improvment of rapid economic growth,the transportation pattern of China’s oil and gas pipeline has been formed which consists of West-East Gas Pipeline Project and North-South Oil Transport ect.But more and more accidents are caused by pipeline corrosion and urban line change.Casing the big-caliber welding is a key link in the process of pipelaying and piperepairs operation,its operation quality directly affects the pipe life and the repair efficiency of oil and gas pipeline.The traditional pipe external interfacing tools has the disadvantages of low operation efficiency and high security risk.At the same time,it is rarely reported that the deformation of the tube and the distance between the weld seams are too large at home and abroad.To this end,the following in-depth study is carried out in this paper:(1)Based on the domestic and overseas large diameter pipe external interfacing tools investigation existing situation,the casing operation functional demand,operation process and working principle has been cleared.External aligning devices、External aligning workbench and pipeline plug mechanical system structure design has been completed.(2)Based on CREO frame concept,three dimensional numerical model has also been established in this paper.The principle of Large bore pipeline-External aligning devices function is described in detail.At the same time,mechanical analysis and strength checking of key mechanism in its working condition has been completed,and the parameters of each structure are calculated.(3)Based on elastic,plastict theory and applying ABAQUS into the pipe orifice reshaping research.The results show that:The stress changes in the pipe mouth are divided into four stages:stress growth,stress constant,stress drop and stress rebound.For the local arch deformation of the pipe in 5mm,10mm and 20mm,the rate of pipeline recovery is 89.8%,87.6%and 85.6%after reshaped.So the reshaping ability is good.But for holistic elliptical deformation,the reshaping ability is bad.(4)In order to realize the distance adjustment of the weld seam,the tensile properties of large bore buried pipeline are studied.An equivalent and infinite pipeline length pipeline-soli coupling numerical model was built and fitting out the tensile force and the formula of each parameter.The results show that:the influence of all factors on the size of tensile force is tensile displacement,radius-thickness ratio of pipeline,excavation length,burial depth,friction coefficient,elastic modulus of backfill soil in turn.The small displacement stretching of the pipe is a feasible method to solve the large distance between the welding seam and the weld.(5)According to the working principle and structural parameters of Large bore pipeline-External aligning devices,its hydraulic system is designed and hydraulic components are selected.The design of mathematical modeling and feedback control strategy for valve controlled cylinder have been done.Applying AMESim into the hydraulic system research.ζ=1 and K=200 are the optimization of control parameters.The results show that:The design of hydraulic system and control strategy can realize the large bore pipe external aligning device of synchronous and precise control of welding seam spacing etc.(6)According to the replacement condition of the large bore pipe of Sulige,this paper detailedly design replacement process of large bore pipeline.It provides a basis for guiding the design of large bore pipeline and it’s supporting tools in the field. |
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