This guide specifies standard specification for alloy steel castings, which have been subjected to special heat treatment, for valves, flanges, fittings, and other pressure-containing parts intended primarily for high-temperature service. All castings shall receive a heat treatment proper to their design and chemical composition. Heat treatment shall be performed before machining except in instances when reheat treating is necessary. The steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, chromium, molybdenum, and vanadium. Steel used for the castings shall conform to the required tensile properties such as tensile strength, yield strength, and elongation. When methods involving high temperature are used in the removal of discontinuities, casting shall be preheated to at least the minimum temperatures.

1.1 This specification covers alloy steel castings, which have been subjected to special heat treatment, for valves, flanges, fittings, and other pressure-containing parts (Note 1) intended primarily for high-temperature service.

1.2 The high-temperature properties of the materials covered in this specification are dependent upon special heat treatment that is required. Although the high-temperature properties are not specified, they are implied by control of chemistry, heat treatment, and room-temperature properties.

1.3 Two grades of ferritic alloy steel are covered (Note 2). Selection will depend on the design and service conditions, mechanical properties, and high-temperature characteristics.

1.4 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 non-conformance with the standard.