Abstract: Based on the equivalence of tension and bendingstiffness, the tube bundle in the fixed tube-sheet kettle-type re-boilerwith slant conical shell was considered as an equivalent cylinder.According to the equivalence of axial load and Poission' effect, thepressures acting respectively on the circular tubing area of the sheet and on tubeswere converted into corresponding equivalent pressures.A simplified model was thus established for the slant conical shellstress analysis in which the tube-sheet and tube bundle was expected to beconsidered. Finite element analysis indicates that a considerable bending stressoccurs at the knuckle region of the big side.Based on the design analysis, SIFs(Stress Intensity Factors) are worked out and SIF curves are given for the knuckle region of the bigside.