Design of Steam Piping and Valves for 1100 F

Abstract Results are available from extended research on the behavior of austenitic and ferritic steels in a steam atmosphere at 1100 F. Allowable stresses at temperatures up to 1110 F and higher have been assigned by code committees with respect to long-time strength as determined from creep and stress-to-rupture tests. Two large boiler-turbine units employing austenitic piping for 1100 F throttle steam temperature are being installed in 1953. Austenitic steels are definitely expensive, however, and alloying elements, particularly nickel and columbium, are in short supply. The present paper reviews existing data and speculates on whether low-alloy-content ferritic steels could be made to serve the purpose. Spot comparisons are made of the relative cost of austenitic and ferritic steel pipe of equivalent carrying capacity. (See Table 1 for identification of the austenitic and ferritic steels considered.)