FURTHER INVESTIGATIONS IN TUBESHEET DESIGN FOR A U-TUBE HEAT-EXCHANGER

A tubesheet for U-tubesheet heat exchanger is analyzed as an equivalen t solid circular plate having complete isotropy in the plane of the tu besheet with usual effective elastic constants. However, the tubesheet is expected to have different values of modulus of elasticity modulus of rigidity, and Poisson's ratio in the thickness direction. This ani sotropic behavior of the tubesheet in thickness direction is taken int o account by using the anisotropic theory of plates. When performing t heoretical analysis, normal stress in thickness direction is also not assumed equal to zero. Hence, the resulting expressions for deflection and bending stresses are closer to those of a thick plate. Expression for radial stress is compared with that of an isotropic thin circular plate. Based on this comparison, certain modifications in the existin g code formulas are proposed. Some design aspects related to ligament efficiency, effective elastic constants, and tubesheet edge conditions are also discussed, Proposed modifications in the design procedure ma y lead to six to ten percent saving in the material cost.