Metal Ball Valves - Flanged Threaded and Butt-Welding Ends
API STANDARD 608-2002
1 Scope
1.1
This standard covers metal ball valves used in on-off service that have butt-welding or flanged ends for nominal pipe size 1/2 through NPS 12 and threaded or socket-welding ends for sizes NPS 1/2 through NPS 2, corresponding to the nominal pipe sizes in ASME B36.10M.
1.2
This standard covers additional requirements for ball valves that are otherwise in full conformance to the requirements of ASME B16.34, Standard Class.
1.3
This standard covers flanged and butt-welding end valves in Standard Classes 150 and 300 and threaded and socket-welding end valves in Standard Classes 150, 300, and 600.
1.4
Figure 1 illustrates a floating ball valve and Figure 2 illustrates a trunnion-mounted ball valve. Both Þgures are to be used only for the purpose of establishing standard nomenclature for valve parts.
2 References
The most recent edition or revision of the following standards and codes shall, to the extent speciÞed herein, form a part of this standard:
API Std 598 Valve Inspection and Testing
API Std 607 Fire Test for Soft-Seated Quarter-Turn Valves
ASME B1.1 Unified Inch Screw Threads(UN and UNR Thread Form)
ASME B1.20.1 Pipe Threads, General Purpose (Inch)
ASME B16.5 Pipe Flanges and Flanged Fittings
ASME B16.10 Face-to-Face and End-to-End Dimensions
ASME B16.11 Forged Fittings, Socket Welding and Threaded
ASME B16.20 Metallic Gaskets for Pipe Flanges-Ring-Joint, Spiral-wound and Jacketed
ASME B16.25 Butt-welding Ends
ASME B16.34 Valves-Flanged, Threaded, and Welding End
ASME B18.2.2 Square and Hex Nuts
ASME B31.3 Process Piping
ASME B36.10M Welded and Seamless Wrought Steel Pipe
MSS SP-45 Bypass and Drain Connections
The ball valve products range: API ball valve, floating ball valve, trunnion ball valve, pipeline ball valve, pneumatic ball valve, soft seal ball valve, Three way ball valve, High pressure ball valve, Metal to metal sealed ball valve.
3 Pressure-temperature Ratings
3.1 VALVE RATING
API Standard 608 The valve pressure-temperature rating shall be the lesser of the shell rating or the seat rating.
3.2 SHELL RATING
The valve shell pressure-temperature rating shall be the rating for the shell material as listed for Standard Class in ASME B16.34. (See 5.1 for definition of shell and description of shell materials.)
3.3 SEAL
3.3.1 Seat Ratings for PTFE
The design shall be such that, when either polytetrafluoroethylene (PTFE) or reinforced PTFE is used for seats, the valve service pressure-temperature ratings shall equal or exceed those specified in Table 1.
3.3.2 Seat Ratings—Other Materials
Seat ratings for other seat materials shall be the manufacturer 's standard; however, the assigned value service pressuretemperature rating shall not exceed that of the valve shell.
4 Design
4.1 GENERAL
Valves manufactured in accordance with this standard shall meet the requirements of Standard Class valves per ASME B16.34 and additional requirements as specified in this standard.
4.2 BODY
4.2.1
The thickness of the valve body shall be in accordance with the requirements of ASME B16.34.
4.2.2
Face-to-face dimensions of ßanged valves and endto-end dimensions of butt-welding end valves shall conform to ASME B.16.10 long or short pattern.
4.2.3
End-to-end dimensions of threaded and socket weld end valves shall be per the manufacturer's standard.
4.2.4
The dimensions and facing finish of end flanges shall conform to ASME B16.5.
4.2.5
Butt-welding ends shall conform to the requirements of ASME B16.25.
4.2.6
Dimensions of socket weld ends shall be in accordance with ASME B16.11 except that the minimum end wall thickness shall be in accordance with Table 4 of ASME B16.34.
4.2.7
Threaded end connections shall have taper threads in accordance with ASME B1.20.1 and the minimum end wall thickness shall be in accordance with Table 4 of ASME B16.34.
4.2.8
Upstream sealing trunnion mounted valves shall have a test plug to test seats as specified in API Std 598. Additional tapped test openings are permitted only if specified in the purchase order. Tapped openings shall be tapered pipe thread per ASME B1.20.1.
4.2.9
If drain or bypass connections are specified by the purchaser, they shall conform to ASME B16.34 or MSS SP-45, as applicable.
4.3 VALVE PORT SIZES
Full-port, regular-port, and reduced-port valves shall have a flow passage through which a cylinder with the diameter shown in Table 2 can be passed when valve handle is moved to the full open limit stop.
4.4 ELECTRICAL CONTINUITY
When specified in the purchase order, valves shall incorporate an antistatic feature that ensures electrical continuity between the stem and the body, or stem, body, and ball. The gate valve shall have electrical continuity across the discharge path with a resistance of not more than 10 ohms. To test for continuity, a new, dry valve shall be cycled at least five times, and the resistance shall then be measured using a DC power source not exceeding 12 volts.
4.5 OPERATION
4.5.1
Unless otherwise speciÞed in the purchase order, manually operated valves shall be equipped with lever-type handles.
4.5.2
Gear operators are recommended for NPS 6 and larger valves. Gear-operated valves shall be provided with handwheels.
