Fatigue-strength-reduction factors for welds in pressure vessels and piping

Fatigue-strength-reduction factors (FSRFs) are used in the design of pressu re vessels and piping subjected to cyclic loading. This paper reviews the b ackground and basis of FSRFs that are used in the ASME Boiler and Pressure Vessel Code, focusing on weld joints in Class 1 nuclear pressure vessels an d piping. The ASME Code definition of FSRF is presented. Use of the stress concentration factor (SCF) and stress indices are discussed. The types of w elds used in ASME Code construction are reviewed. The effects of joint conf iguration, welding process, cyclic plasticity, dissimilar metal joints, res idual stress, post-weld heat treatment, the nondestructive inspection perfo rmed and metallurgical factors are discussed. The current status of weld FS RFs, including their development and application, are presented. Typical fa tigue data for weldments are presented and compared with the ASME Code fati gue curves and used to illustrate the development of FSRF values from exper imental information. Finally, a generic procedure for determining FSRFs is proposed and future work is recommended. The five objectives of this study were as follows: 1) to clarify the current procedures for determining value s of fatigue-strength-reduction factors (FSRFs); 2) to collect relevant pub lished data on weld-joint FSRFs; 3) to interpret existing data on weld-join t FSRFs; 4) to facilitate the development of a standard database of FSRFs f or weld joints; and 5) to facilitate the development of a standard procedur e for determining the values of FSRFs for weld joints. The main focus is on weld joints in Class 1 nuclear pressure vessels and piping. [S0094-9930(00 )02703-7].