API STD 594-2017 pdf free download
API STD 594-2017 pdf free download.Check Valves: Flanged, Lug, Wafer, and Butt-welding.
3.2 DN An alphanumeric designation of size that is common for components used in a piping system, used for reference purposes, comprising the letters “DN” followed by a dimensionless number indirectly related to the physical size of the bore or outside diameter of the end connection as appropriate. The dimensionless number following “DN” does not represent a measurable value and is not used for calculation purposes except where specified. 3.3 NPS An alphanumeric designation of size that is common for components used in a piping system, used for reference purposes, comprising the letters “NPS” followed by a dimensionless number indirectly related to the physical size of the bore or outside diameter of the end connection as appropriate. The dimensionless number may be used as a valve size identifier without the prefix “NPS.” The dimensionless size identification number does not represent a measurable value and is not used for calculation purposes. 4 Pressure-temperature Ratings 4.1 Valve Rating 4.1.1 The pressure-temperature rating of the valve for various body materials shall be as follows: — Type “A” valves only: a) gray iron: the pressure-temperature rating for the applicable flange class as specified in ASME B1 6.1 ; b) ductile iron: the pressure-temperature rating for the applicable flange class as specified in ASME B1 6.42. — Type “A” and Type “B” valves: a) Steel, nickel alloy, and other alloy: The pressure-temperature rating shall be in accordance with Standard Class ratings of ASME B16.34, Table 2, for the applicable Group 1, 2, or 3 material of ASME B16.34. b) Special materials: The pressure-temperature rating for materials not covered by ASME B1 6.34 shall be de- termined by the procedures in ASME B1 6.34. 4.2 Temperature Restrictions 4.2.1 Restrictions of temperature and concurrent pressure, or pressure and concurrent temperature (e.g. those imposed by special soft seals or special trim materials), shall be marked on the valve nameplate (see Section 8).
5 Design 5.1 Body and Cover 5.1.1 The minimum body wall thickness for various materials shall be as follows: — Type “A” valves only: a) gray iron: as shown in Table 1 for Class 1 25 and Class 250 only; b) ductile iron: as shown in Table 1 for Class 150 and Class 300 only. — Type “A” and Type “B” valves: a) steel and chrome-moly steels per ASME B16.34, as shown in Table 1, for Classes 150, 300, 600, 900, 1500, and 2500; b) corrosion-resistant steels per ASME B16.34, Table 1 , Group 2, and nickel-based alloys per ASME B16.34, Table 1 , Group 3, as shown in ASME B16.34, Table 3. Other wall thicknesses shall be as agreed be- tween purchaser and manufacturer. c) special materials: The minimum body wall thickness for materials not covered by ASME B16.34 shall be as agreed between the purchaser and manufacturer. 5.1.2 The face-to-face dimensions shall be as follows: — Type “A” valves (including valves with ring-joint facings) shall conform to those shown in Table 2 and Table 3. — Type “B” valves shall conform to ASME B16.10 long pattern. — For Type A or Type B valves, special lengths are only permitted by agreement between purchaser and manufacturer. 5.1.3 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 adequate. 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 or ASME B16.47, and have butt-welding ends for use without backing rings. Flanges for iron valves shall only be the integral type.
