scope:

Recent advances in bounding techniques and simplified methods of analysis for components operated in the creep regime are used herein to obtain some very useful design guides. Bounds on stresses during periods of elevated temperature operation are used to evaluate creep rupture damage. Bounds on strain ranges are used to evaluate creep fatigue damage. Bounds on accumulated strains including creep ratcheting are used to evaluate margins against ductility limits. The effect of choosing different wall thicknesses on each of these damage mechanisms is determined for a wide range of dimensionless design parameters, operating pressures and cyclic thermal conditions, and material properties. The solutions are based on the uniaxial model.