The Finite Element Analysis Of Stress About Directly Buried Heating Stamped Tee

The tee as a very important local part of directly buried heating pipeling,chich is used frequently and also is a vulnerable spot.It plays a vital role in the field of safe and stable operation of pipeline.In addition,the research of tee in this field is obviously lag behind the elbow and reducer.In particular,the using of stamped tee is more and more widely,research results are very few.In order to solve this situation,reference research methods of tee in the field of petroleum chemical industry and machinery,this paper analyses the change rule of stress about tee especially stamped tee under the action of an internal pressure alone and under the action of internal pressure and temperature load together using the ANSYS finite element simulation method.The main content of this paper includes six parts.First chapter elaborates selected topic background and research status from central heating to directly buried pipeline and tee,briefly expounds the research methods and contents of the paper with the significance of the topic.The second chapter theory analyzes directly buried heating pipe load types and different stress produced by the different load,classifies modes of pipeline failure which may be led by stress,points out clearly the modes of pipeline failure are plastic deformation and low cycle fatigue damage.The third chapter illustrates the processing technology of stamped tee and welded tee with the brief introduction of tee,then point out that stamped tee is better than welded tee through the eomparion of them.In the end,Presents a new type about tee proeessing technology.The fourth chapter analyses and compares the calculation methods of infinite plastic deformation and low eycle fatigue damage stress for tee at home and abroad,introduces calculation methods of straight pipe and the wall thickness for welded tee at home and abroad,mainly aiming at the two failure modes of tee.Calculate the critical stress based on the Parr’s green-minas formula and S-N curve in Europe code in order to determine whether the tee under the different requirements and levels meets the requirements of the safety of the low cycle fatigue damage.Then analyzes of the reinforcement method and theory of tee through the introducion of tee construction method.In the fifth chapter,using ANS YS finite element software abtains results of the study of tee model especially stamped tee under the loads of pressure and temperature:(1)Under pressure load,gets the stress distribution rile of three critical path in high stress area,finds the maximum equivalent stress points of welded tee in the shoulder lining,while with the increase of corner radius the maximum equivalent stress points of stamped tee has a trend to move from the shoulder to the abdomen on both sides;finds that the main factors of stress concentration is tangential stress,and the effect of axial stress is small;obtains the stress of welded tee maximum minimum equivalent stress ratio and the ratio of the maximum equivalent stress values with stamped tee and welded tee;gets the change rule of equivalent stress values of stamped tee with the variation of comer radius,local wall thickness.(2)Under pressure and temperature loads,gets the stress distribution rile of three critical path in high stress area,finds the maximum equivalent stress points of welded tee in the abdomen lining,while with the increase of coner radius the maximum equivalent stress points of stamped tee has a trend to move from the abdomen to the abdomen on shoulder both sides;finds that the main factors of stress concentration is axial stress,and the effect of radial stress is small;obtains the ratio of the maximum equivalent stress values with stamped tee and welded tee;gets the change rule of equivalent stress values of stamped tee with the variation of corner radius,local wall thickness and branch pipe length.(3)Finds the simulated value of pressure and temperature load can well satisfy the superposition principle;compares to pressure load and temperature loads,temperature load is the main factor,pressure load is very minor factors.(4)Under pressure and temperature loads,tee abdomen happens to bulge deformation,while shoulder happens to collapse deformation.(5)Finds that 90° tee is superior to the parallel branch and 45° tee;analysis the effect of the shawl reinforce and floor reinforce of welded tee and floor reinforce of stamped tee.(6)Gets different conclusions of elastic-plastic analysis with elastic analysis.In sixth chapter,summarize the research achievements of this paper,point out the deficiency of this article,and put forward the research direction of stamped tee in the future.