API St 608-2012 pdf free download

API St 608-2012 pdf free download.Metal Ball Valves—Flanged, Threaded, and Welding Ends.
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. 4.3.2 Seat Ratings—Other Materials Seat pressure-temperature ratings for seat materials other than PTFE or R-PTFE shall be the manufacturer’s standard. Seats made from hard materials such as solid cobalt chrome alloy, ceramics, or metal seats coated with hard materials such as carbide coatings are also acceptable and shall have seat pressure-temperature ratings per the manufacturer’s standard. The published seat pressure-temperature ratings shall not exceed the manufacturer’s published shell ratings.
5.3 Body 5.3.1 The wall thicknesses of the valve body (see note) shall be in accordance with the requirements of ASME B1 6.34 for the applicable Standard Class. ASME wall thicknesses are based on the Standard Class of valve and not the pressure-temperature ratings of 4.1. NOTE Body may be comprised of multiple components, such as body, body cap, etc. 5.3.2 Face-to-face dimensions of flanged valves and end-to-end dimensions of butt-welding end valves shall conform to ASME B16.1 0 ball valves—long or short pattern. 5.3.3 End-to-end dimensions for threaded and socket-welding end valves shall be per the manufacturer’s standard. 5.3.4 The dimensions and facing finish of end flanges shall conform to ASME B1 6.5. 5.3.5 Butt-welding ends shall conform to the requirements of ASME B1 6.25 with an inside diameter (denoted as B in ASME B16.25) tolerance per ASME B1 6.34. DN 50 (NPS 2) and smaller butt-weld end valves shall conform to API 602. 5.3.6 Socket-welding ends shall conform to the requirements of ASME B1 6.11 , except minimum wall thicknesses shall conform to Table 4 of ASME B16.34. 5.3.7 Threaded ends shall have taper pipe threads in accordance with ASME B1.20.1 , and the minimum wall thicknesses shall conform to Table 4 of ASME B1 6.34. 5.3.8 End flanges and bonnet flanges shall be cast or forged integral with the body; except that cast or forged flanges attached by full penetration butt-welding may be used if agreed to by the purchaser. Valves having flanges attached by welding shall meet the requirements of Paragraph 2.1 .6 of ASME B16.34.