ASSESSING FLANGED JOINT LEAKAGE AND TUBE-TO-TUBESHEET JOINT FAILURE DUE TO FLUID TEMPERATURE DIFFERENTIALS IN A FLOATING HEAD HEAT EXCHANGER USING FINITE ELEMENT ANALYSIS

摘要

This paper uses three dimensional (3D) finite element analysis (FEA) to investigate the likelihood of leakage at the head-to-tubesheet joint and the possibility of failure at the tube-to-tubesheet joints due to temperature differentials between the shell-side and tube-side process fluid in a four-pass, floating head heat exchanger. The gasket at the floating head-to-tubesheet joint is explicitly modeled and the flange bolts are included with the appropriate amount of preload. Steady-state heat transfer analysis is performed on the 3D model to obtain realistic temperature gradients that are used to evaluate the system behavior in the ensuing structural analyses. Furthermore, different methods of approximating the stiffness of the tube bundle and the corresponding gasket stresses and tubesheet deflections are investigated in detail and compared. These comparisons indicate that simplified methods of modeling the tube bundle permit efficient thermal-mechanical evaluation of complex, multi-pass heat exchangers while achieving reasonable tubesheet and flanged joint behavior.