1. Scope 1.1 This specification covers two general classes, WP and CR, of wrought austenitic stainless steel fittings of seamless and welded construction covered by the latest revision of ANSI B16.9, ANSI B16.11, ANSI B16.28, MSS Standard Practice SP-79, MSS Standard Practice SP-43 and MSS SP-95. Fittings differing from these standards may be furnished in accordance with Supplementary Requirement S9. 1.1.1 Class WP fittings are subdivided into four subclasses: Classes WP-S, WP-W, WP-WX and WP-WU. They are manufactured to the requirements of ANSI B16.9, B16.11, B16.28, or MSS Standard Practice SP-79, and they shall have pressure ratings compatible with 9.2. Class WP-S fittings are those manufactured from seamless product by a seamless method of manufacture (marked with class symbol WP-S); Class WP-W fittings contain welds made with or without filler metal. Pipe or fitting fabrications made with filler metal have been radiographed (marked with Class symbol WP-W); Class WP-WX fittings are those which contain welds where all welds have been radiographed (marked with class symbol WP-WX); and Class WP-WU fittings are those which contain welds where all welds have been ultrasonically tested (marked with class symbol WPWU). 1.1.2 Class CR fittings are those manufactured to the requirements of MSS SP-43, and they shall have pressure ratings compatible with 9.3. 1.2 This specification does not apply to cast fittings. Cast austenitic-steel piping fittings are covered by Specifications A351/A351M, A743/A743M, and A744/A744M. 1.3 Optional supplementary requirements are provided. When desired, one or more may be specified in the order. 1.4 This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable "M" specification designation (SI units), the material shall be furnished to inch-pound units. 1.5 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.