API St 608-2012 pdf download.Metal Ball Valves—Flanged, Threaded, and Welding Ends.
1 Scope 1.1 This standard specifies the requirements for metal ball valves suitable for petroleum, petrochemical, and industrial applications that have: — flanged ends in sizes DN 1 5 through DN 600 (NPS 1 / 2 through NPS 24); — butt-welding ends in sizes DN 1 5 through DN 600 (NPS 1 / 2 through NPS 24); — socket-welding ends in sizes DN 8 through DN 50 (NPS 1 / 4 through NPS 2); — threaded ends in sizes DN 8 through DN 50 (NPS 1 / 4 through NPS 2). Corresponding to the nominal pipe sizes in ASME B36.10M. 1.2 This standard applies to metal ball valves with pressure classes as follows: — flanged ends in Classes 1 50, 300, and 600; — butt-welding ends in Classes 150, 300, and 600; — socket-welding ends in Classes 1 50, 300, 600, and 800; — threaded ends in Classes 150, 300, 600, and 800. 1.3 This standard establishes requirements for bore sizes described as: — full bore; — single reduced bore; — double reduced bore. 1.4 This standard applies to floating (seat-supported) ball (Figure B.1) and trunnion ball valve designs (Figure B.2). These figures are to be used only for the purpose of establishing standard nomenclature for valve components— other floating and trunnion designs also exist. 1.5 This standard establishes additional requirements for ball valves that are otherwise in full conformance to the requirements of ASME B1 6.34, Standard Class. 2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. API Standard 598, Valve Inspection and Testing API Standard 607, Fire Test for Quarter-turn Valves and Valves Equipped with Non-metallic Seats ASME B1.1 1 , Unified Inch Screw Threads (UN and UNR Thread Form)
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 the letters Class followed by a dimensionless whole number. The number following the letters 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 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 in this standard. 3.3 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 The valve pressure-temperature rating shall be the lesser of the shell rating or the seat rating. 4.2 Shell Rating The valve shell pressure-temperature rating shall be the rating for the shell material as listed for Standard Class in ASME B1 6.34 (see 6.1 for definition of shell and description of shell materials). 4.3 Seat and Seal Rating 4.3.1 Seat Ratings for PTFE and R-PTFE Valves employing polytetrafluoroethylene (PTFE) or modified PTFE seats and valves employing reinforced polytetrafluoroethylene (R-PTFE) or modified R-PTFE seats shall have pressure-temperature ratings equal or higher than the values shown in Table 1 and Table 2.