Fatigue assessment of vessels

During operation the shell, or components of the vessel, may be subjected to cyclic stresses. Stress cycling can arise from the following causes  

A detailed fatigue analysis is required if any of these conditions is likely to occur to any significant extent. Fatigue failure will occur during the service life of the vessel if the endurance limit (number of cycles for failure) at the particular value of the cyclic stress is exceeded. The codes and standards should be consulted to determine when a detailed fatigue analysis must be undertaken. 

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Division 1. Below the creep range, design stresses are based on one-fourth of the tensile strength or two-thkds of the yield, or 0.2% proof stress. Design procedures are given for typical vessel components under both internal pressure and external pressure. No specific requkements are given for the assessment of fatigue and thermal stresses. 

M. Ando, Y. Hirose, T. Karato, S. Watanabe, O. Inoue, N. Kawasaki, Y. Enuma, Comparison and assessment of the creep-fatigue evaluation methods with notched specimen made of Mod.9Cr-lMo steel, J. Pressure Vessel Technol. 136 (4) (2014) 041406-041406-10. 

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