API STD 594:2017 pdf free download.Check Valves: Flanged, Lug, Wafer, and Butt-welding
2 Normative References
The following referenced documents are indispensable for the application of this document. Unless otherwise cited
by specific revision or date, the latest edition of the referenced documents (including any amendments) applies.
API Standard 598, Valve Inspection and Testing ASME B1.1
1 , Unified Inch Screw Threads (UN and UNR Thread Form)
ASME B1.13M, Metric Screw Threads: M Profile
ASME B16.1, Gray Iron Pipe Flanges and Flanged Fittings Classes 25, 125, and 250
ASME B16.5, Pipe Flanges and Flanged Fittings
ASME B16.10, Face-to-Face and End-to-End Dimensions of Valves
ASME B16.11, Forged Fittings, Socket-Welding and Threaded
ASME B16.14, Ferrous Pipe Plugs, Bushings, and Locknuts with Pipe Threads
ASME B16.25, Buttwelding Ends
ASME B16.34, Valves—Flanged, Threaded, and Welding End
ASME B16.42, Ductile Iron Pipe Flanges and Flanged Fittings: Classes 150 and 300
ASME B16.47, Large Diameter Steel Flanges; NPS 26 Through NPS 60 Metric/Inch Standard
ASME BPVC, Section VIII
ASME BPVC, Section IX
MSS-SP-6 2 , Standard Finishes for Contact Faces of Pipe Flanges and Connecting-End Flanges of Valves and Fittings
3 Terms and Definitions
For the purposes of this document, the following definitions apply.
3.1
class
An alphanumeric designation that is used for reference purposes relating to valve pressure/temperature capability,taking into account valve material mechanical properties and valve dimensional characteristics. It comprises “Class”followed by a dimensionless whole number. The number following “Class” does not represent a measurable value and is not used for calculation purposes except where specified in this standard. The allowable pressure for a valve having a class number depends on the valve material and its application temperature and is to be found in tables of pressure/temperature ratings.
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).
4.2.2 The temperature for a corresponding pressure rating is the maximum temperature of the pressure-containing shell of the valve. In general, this temperature is the same as that of the contained fluid. The use of a pressure rating corresponding to a temperature other than that of the contained fluid is the responsibility of the user.
4.2.3 For temperatures below the lowest temperature listed in the pressure/temperature tables, the service pressure shall be no greater than the pressure for the lowest listed temperature. The use of valves at lower temperatures is the responsibility of the user. Consideration should be given to the loss of ductility and impact strength of many materials at low temperature.API STD 594 pdf download.API STD 594:2017 pdf free download
