API 594-2010 pdf free download

API 594-2010 pdf free download.Check Valves: Flanged, Lug, Wafer, and Butt-welding.
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 International 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 dimension number DN An alpha numeric 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 nominal pipe size NPS An alpha numeric 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 B16.1; b) ductile iron: the pressure-temperature rating for the applicable flange class as specified in ASME B16.42. — 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, Table 1. b)special materials: The pressure-temperature rating for materials not covered by ASME B16.34 shall be determined by the procedures in ASME B16.34, Appendix B. 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 identification plate (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. 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 Tables 1 and 2 for Class 125 and Class 250 only; b)ductile iron: as shown in Tables 1