This specification covers one grade of martensitic stainless steel and several grades of ferritic steel castings for cylindrical (shells), valve chests, throttle valves, and other heavy-walled castings for steam turbine applications. The steel shall be made by the open-hearth or electric-furnace process. Deoxidation of the carbon and low-alloy steel grades shall be by manganese and silicon. The castings shall be heat treated in either the normalized, tempered, or stress-relieved conditions. Mechanical properties such as tensile strength, yield strength, and elongation shall be determined by subjecting the specimens to a tension test.

1.1 This specification covers one grade of martensitic stainless steel and several grades of ferritic steel castings for cylinders (shells), valve chests, throttle valves, and other heavy-walled castings for steam turbine applications.

1.2 Optional supplementary requirements (S1 through S5) shall apply as selected by and specified by the purchaser.

1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.