A Study on Welding Residual Stress in Elliptical Tube to Tube Sheet Joint of a Phthalic Anhydride Switch Condenser

Abstract Switch condenser is widely used in petroleum and chemical industries, especially in phthalic anhydride plants. The tube to tube sheet joint is an important element for the switch condenser. The welding residual stress in the tube to tube sheet joint is critical to the safety and reliability of the switch condenser. In this paper, FEM was used to predict the welding residual stress in the elliptical tube to tube sheet weld of a phthalic anhydride switch condenser. In order to validate the simulated results, a test sample with circular-shaped tube to tube sheet joint was prepared. And then the welding residual stresses in the circular tube to tube sheet weld were simulated by the FEM and studied experimentally by the X-ray diffraction method. The simulated results were compared with the test results to verify the finite element analysis. The simulated results show that the residual stress initially decreased sharply and then decreased gradually with the increase of the distance along the direction of the long axis of the elliptical weld. It is found that the maximum welding residual stress in the elliptical tube to tube sheet joint appeared at the location of 180° in the region of the elliptical weld and reached its peak value. Experimental results are in good agreement with the numerical simulation results.