Weld Residual Stress in Tube to Tube Sheet Joints of a Heat Exchanger by Experimental and Finite Element Simulation

Shell-and-tube heat exchangers are widely used in petrol and petro-chemical industries. But weld residual stresses are generated in the tube-to-tube sheet joint and have a great effect on stress corrosion cracking. Therefore, a good prediction and an efficient evaluation of the weld residual stress are necessary to assure the structure integrity. In this work, X-ray diffraction measurement and finite element method have been used to study the residual stress distribution. The results show that the large tensile residual stresses, which have exceeded the yield stress, are generated in the tube to tube sheet joints, leading that the joints become the weakest parts of the heat exchanger. In the central surface part, a wave shape stress distribution is generated along the centerline of tube 1 and tube 3.