1.1 This specification covers austenitic steel castings for valves, flanges, fittings, and other pressure-containing parts (Note 0). Note 0Carbon steel castings for pressure-containing parts are covered by Specification A 216/A 216M, low-alloy steel castings by Specification A 217/A 217M, and duplex stainless steel castings by Specification A 995/A 995M.
1.2 A number of grades of austenitic steel castings are included in this specification. Since these grades possess varying degrees of suitability for service at high temperatures or in corrosive environments, it is the responsibility of the purchaser to determine which grade shall be furnished. Selection will depend on design and service conditions, mechanical properties, and high-temperature or corrosion-resistant characteristics, or both.
1.2.1 Because of thermal instability, Grades CE20N, CF3A, CF3MA, and CF8A are not recommended for service at temperatures above 800F [425C].
1.2.2 Because of embrittlement phases, Grade CD4MCu is not recommended for service at temperatures above 600F [316C].
1.3 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The Supplementary requirements shall apply only when specified individually by the purchaser in the purchase order or contract.
1.4 This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract specifies the applicable M specification designation (SI units), the inch-pound units shall apply. 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 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.
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