Finite Element Analysis and Stress Intensification Factor Determination for Core to Jacket Joints

In this study Stress Intensification Factor (“SIF”) and stress analysis for core to jacket joints are investigated. The three-dimensional finite element shell model consists of two shells: the jacket and the core. The effect of the welded joint discontinuity is taken into account by applying a stress concentration factor. It is presumed that the core and shell are ASTM A-106 GR B [1]. The joint is modeled for different pipe-outside diameters and wall-thicknesses and SIF is calculated for different Head shapes, which are discussed further in this paper. The model is examined with different mesh types and the results are discussed. Temperature gradient in pipe wall-thickness causes thermal stress. The thermal stress, combined with operating, sustained and differential expansion stress are considered in the stress analysis of core and jacket shell. The results for different temperature gradients are compared. The imposed displacement loads caused by global temperature difference between core and the jacket are taken from a beam model run of a typical discontinuous steam jacketed piping system.