API 594:2004 pdf download.Check Valves: Flanged, Lug, Wafer and Butt-welding
1.3 VALVE NOMENCLATURE
The standard nomenclature for valve parts is shown in Fig- ures 1, 2, 3, 4 and 5. Figures 1, 2, 3 and 4 illustrate typical Type ‘A’ check valves and Figure 5 illustrates a typical Type ‘B’ check valve. These figures show typical designs only and are not to be construed as precluding other available designs that comply with the requirements of this standard. The only purpose of these figures is to identify part names. The con- struction of a valve is acceptable only when it complies with this standard in all respects.
4 Design
4.1 BODY AND COVER
4.1.1 The minimum body wall thickness for various mate- rials shall be as follows: Type ‘A’ valves only: a. Gray iron: as shown in Tables 1A and 1B for Class 125 and Class 250 only. b. Ductile iron: as shown in Tables 1A and 1B for Class 150 and Class 300 only. Type ‘A’ and Type ‘B’ valves: c. Steel and chrome-moly steels per ASME B16.34, Table 1, Group 1: as shown in Tables 1A and 1B, for Classes 150, 300, 600, 900, 1500 and 2500 d. Nickel-base alloys per ASME B16.34, Table 1, Group 2 and other alloys per ASME B16.34, Table 1, Group 3: 1. For Classes 150, 300 and 600 only: as shown in ASME B16.34, Table 3. 2. For Classes 900, 1500 and 2500: as shown in Tables 1A and 1B. e. Special materials: The minimum body wall thickness for materials not covered by ASME B16.34 shall be as agreed between the purchaser and manufacturer.
4.1.2 The face-to-face dimensions shall be as follows: Type ‘A’ valves (including valves with ring-joint facings) shall con- form to those shown in Tables 2A and 2B. Type ‘B’ valves shall conform to ASME B16.10. Short pattern or special lengths are not permitted unless by agreement between pur- chaser and manufacturer.
4.1.3 The purchase order shall specify for Type ‘A’ valves whether the body type shall be wafer, lug or double flanged and for Type ‘B’ valves whether the body type shall be flanged or butt-welding. Type ‘A’ double-flanged valves will only be supplied where nut space between flanges is ade- quate. End and cover flanges of steel, nickel alloy and other alloy valves shall be integrally cast or forged with the body. However, flanges may be attached by full penetration butt- welding if agreed to by the purchaser. Flanges shall conform to ASME B16.5 and have butt-welding ends for use without backing rings. Welding and examination shall conform to ASME B31.3 for Normal Fluid Service, unless otherwise specified, including qualifications for the weld procedure and welder or welding operator.