Experimental Investigation and Elastic-plastic Analysis on ConnectionStrength of Zirconium Tube-tubesheet Joints

摘要

Zirconium tube is widely used in heat exchanger equipments in petrochemical process forsignificant corrosion resistance.The connection joint of tube-tubesheet is the weakest parts in a heatexchanger.The experiment and numerical analysis of different materials (zirconium tubes,titaniumtubes and 16MnR tubesheets,316L tubesheet) joints were performed in this paper.The expansionjoints specimens were prepared at the pressure ranging from 28MPa to 38MPa.And pulling out testwas performed from 20°Cto 300°C.The finite element model of tube-tubesheet joint wasestablished.The effect of expansion pressure,temperature and groove on the pulling out strength ofjoints was analyzed.Both the experiments and the finite element analysis show that the pull-outstrength increases with the increasing expansion pressures.Working temperature also has a greateffect on the connection strength of tube-to-tubesheet joints,especially for the zirconium and 316Ljoints,which have the most significant difference of thermal expansion coefficient between tube andtubesheet.The residual contacting pressure on the contact surface between tubes and the tubesheet isnot uniformly distributed and two tightness bands are found near the surfaces of the tubesheet or atthe two brinks of the groove on the tubesheet hole.Compared with the ungrooved joint,the residualcontacting pressure on the tightness bands for the grooved joint is much higher,indicating a groovedjoint has better tightness.