Rarely does the engineer or metallurgist have an opportunity to evaluate design considerations and laboratory data in terms of creep in service. Carbon-molybdenum steam pipe, carefully measured for service creep during 100,000 hr of operation at 900 F, was subjected to laboratory examination after removal from service. The purpose was to check calculated service creep rates, assess creep damage, and to compare long-time performance prediction based on short-time laboratory data. Remarkable correlation was observed between calculated service creep rates and those established by subsequent laboratory creep testing. Full agreement with average values used by the Subgroup on Allowable Stresses for Ferrous Materials of the ASME Boiler Code Committee in setting allowable stresses for this material was established for both creep and stress-rupture properties.