Steam-Piping Design to Minimize Creep Concentrations

Abstract

Abstract Believing that steam-piping design for high-temperature service has heretofore been based largely upon elastic analysis of expansion stresses without adequate consideration of the importance of high-temperature creep, the author discusses the principles governing the relaxation of expansion stresses during service at high temperature and points out the possibility of creep concentrations in local spots of maximum stress. A number of specific examples are given to show that ordinary piping design usually can be made without such concentrations. Contrariwise, the type of expansion flexibility which invites excessive creep is illustrated. The desirability of cold springing pipe so as to minimize stress at high temperature is emphasized.