VALVE TYPE SPECIFICATIONS
1 BALL VALVES
Ball valves shall be provided with the following:
• Lockable device (opened and closed).
• Blow-out proof stem.
• Split body design.
• Anti static device tested in accordance with ISO 17292 or API 6D as applicable.
• Trunnion mounted ball valves shall have a cavity relief seat.
• Suitable for bi-directional use.
• Ball shall be solid. Hollow ball is subject to MISC/MMHE approval.
• Ball position indicator.
Floating ball valves are acceptable up to 6” in class 150 and 300, 3” in class 600.
Larger sizes shall be trunnion mounted, as indicated in the VDS.
Where soft-seating material is specified in the VDS the SUPPLIER/VENDOR shall confirm suitability for the specified pressure, temperature and service conditions and give advice on any aging and/or service limitations.
2.1 Gate Valves
All gate valves shall be of outside screw and yoke design, bolted bonnet and gland, rising stem with back seat. Wedge shall be one-piece flexible type with the exception of valves NPS 2 and smaller where solid wedge is acceptable. Packing gland shall be of two-piece self-aligning design consisting of gland follower and a separate gland flange.
All gate valves NPS 4 and larger in pressure class 150 and 300, and NPS 3 and larger in pressure class 600 and above, shall be supplied with NPS 3/4 NPT stem seal injection fittings and body drain connections.
2.2 Globe Valves
All globe valves shall be of outside screw and yoke design, bolted bonnet and gland, rising stem with back seat. Disc shall be swivel type design. Packing gland shall be of two-piece selfaligning design consisting of gland follower and a separate gland flange.
All globe valves NPS 4 and larger in pressure class 150 and 300, and NPS 3 and larger in pressure class 600 and above, shall be supplied with NPS 3/4 NPT stem seal injection fittings and body drain connections.
2.3 Check Valves
Swing check valves shall be regular type, straight-through port with metal to metal seating surfaces unless specified otherwise.
Dual-plate check valves shall be retainer less design, spring loaded, metal to metal seating and suitable for vertical and horizontal installation.
Piston check valves shall be of non-slam, metal to metal seating surfaces and spring loaded.
3 BUTTERFLY VALVES
Butterfly valves shall be bi-directional. Where there is a preferred sealing direction this shall be indicated on the valve body. Butterfly valves shall be furnished with the following features:
Suitable for dead-end service
Through drilling bolt holes
Lockable device (opened and closed)
Valve disks shall be positively secured to the shaft. Threaded fasteners shall be locked or tack welded. The disk shall not interfere with the connecting piping at any shaft rotation.
Wrench operators shall be capable of holding the disc in at least five equally spaced intermediate positions between fully opened and fully closed.
QUARTER TURN VALVES
Maximum torque for hand operated quarter turn valves shall be 150Nm at maximum
ASME/API rated differential pressure (334 N of force on a maximum 500 mm lever, with 450 mm lever length used for calculating torque). Valves requiring a breakout torque greater than 150Nm shall be provided with a gearbox and hand wheel. Gear shall be sized such that output torque is minimum 150% of maximum required operating torque of the valve.
For valves with breakout torque exceeding 150Nm, SUPPLIER/VENDOR shall confirm the necessity of a gearbox according to above requirement. Torque test shall be conducted as following:
pressurize valve to design press. in closed position and allow 1 minute to stabilize
operate valve and record torque required to open and close the valve, repeat 3 times
for bi-directional valves, repeat test in reverse direction
Generally following sizes shall be provided with a gearbox, smaller sizes shall be provided with a lever, unless torque exceeds the values specified above:
for 150, 300 and 600# : Full bore above 4”, reduced bore above 6”
Levers shall be maximum 500 mm long and hand wheels shall not exceed 750 mm diameter. Levers and hand wheels shall be suitable for furnishing a locking facility
(pad-lock with chain).
Gearboxes shall be provided with a position indicator. Gearboxes shall be fully resistant to saline marine atmosphere and shall permit lubrication and maintenance.
Components shall not be manufactured from gray or malleable cast iron. The use of aluminum or aluminum alloys is not permitted.
Gear ratios shall be max. 1:60 for valve size 8” and smaller, and max. 1:120 for 10” and above.
RISING STEM VALVES
Gear Operator Requirements for rising stem valve shall be provided as follows: