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

1.2.1 Within the text, the SI units are shown in brackets.

1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.