Stress Evaluation of a Three-Point Supported Heat Exchanger

Abstract

Abstract This paper focuses on developing formula-based method to predict shell stresses in a high-pressure heat exchanger with three-point supports. It compares the results with Finite Element Analysis (FEA) based design procedure. High pressure heat exchanger is supported with two saddles on shell (fixed and sliding saddles) and one lug support on channel due to heavy thk. tubesheet and channel flanges. Heat exchanger vessel part is considered as a hollow circular beam and closed form solutions are derived using continuous beam theory. Three-dimensional (3D) Finite Element model is developed using Ansys® and three types of meshing options are considered i.e., tetrahedron mesh, hex dominant mesh, and shell element mesh. Linear static structural analysis is performed, and shell membrane plus bending stresses are extracted by linearizing the axial stresses along the Stress Classification Lines at four shell locations using PVRC 3D stress criteria (Bulletin WRC 429). Longitudinal membrane plus bending stresses are calculated for the severe most design load case: Internal pressure, superimposed tubesheet weight and ship motion acceleration loads. Stress values which are obtained by formula-based approach and FEA are compared at four shell locations and conclusions are drawn.