Cylindrical shells, stress concentration factors

For Stress Concentration Factors see Stresses in Cylindrical Shells from External Local Loads, Procedure 5-4. 

The cylinder/cylinder geometry (for nozzles in cylindrical vessels) is much more difficult to analyze than the nozzle sphere, which can be treated as an axisymmetric structure. To obtain a suitable stress concentration factor for a nozzle in a cylindrical vessel, an approximate axisymmetric model is sometimes used. A popular approximation used is where the equivalent sphere has twice the diameter of the shell. The general trend of the experimental results is shown in Figure 7.8, which is for a flush nozzle in a cylindrical shell. 

Figure 7.8 Stress concentration factors (SCFs) for a nozzle in a cylindrical shell (approximate). 

Example 11.14. A cylindrical shell that is 36-in. ID by 2.5-in. thick contains a perpendicular nozzle th is 4-in. ID by 0.75-in. thick. The design pressure is 1900 psi at a design temperature of 450°F. The vessel is subjected to cyclic operation and a fatigue analysis is required. Peak stresses and stress concentration factors are not known for the specific geometry to be used. What method can be used to evaluate the peak stresses for a fatigue analysis ... 

Example 11.15. A cylindrical shell that is 84-in. ID by 1.0-in. nominal thickness contains a nozzle 8-in. ID by 1.0-in. nominal thickness. The design pressure is 400 psi and the allowable stress of the material is 17.5 ksi. The nozzle is subjected to an inward radial loading of 12,000 lb and an applied moment in the longitudinal direction of 150,000 in.-lb. What are the combined stresses on the longitudinal axis due to these two external loadings using the Mershon method and the curves in Appendix K The vessel is not subjected to cyclic loading, and therefore no stress concentration factors need be considered. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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