Ball Valve

Ball valves are typically quarter turn valves. By rotating the ball by the operator, via the stem, through 90 Degrees rotation, either an on or off flow condition can be achieved within the process...

The seat to seal interface in a ball valve is made between a highly polished ball and a similarly smooth surfaced seat, retained in the seat pocket of the body and / or the adaptor. Energisation of the seat to seal interface in a floating ball type, is assisted by the pressure in the process. When the valve is closed the process pressure pushes the ball slightly towards the downstream seat, creating a mechanical force against the downstream seat. The process pressure therefore assists the existing mechanical forces inherent in the valve design in creating the seal. In the trunnion mounted ball valve, the ball cannot move. In this design, the process pressure pushes the upstream seat against the upstream side of the ball. In trunnion mounted ball valves it is common to have mechanical assistance for the seal by using either Beleville washer springs or spiral wound springs in behind the seat holder. Ball Valves are generally either 2 or 3 piece bolted construction, however, in the pipeline industry, valves are very often all welded for safety reasons.

The primary function of a ball valve is for creating isolation i.e. on or off. Secondary function can be flow reduction which is restricted by a reduced bore in the ball and tapered profile in the adaptors. Ball valves must never be used for throttling (i.e. using the ball in any semi open / closed position) as this can result in erosion of the sealing surface. Ball valves which have been used for throttling will generally show a wear pattern on the leading edge of the ball bore.
Read More

Ball Valve Specification

Click for more Ball Valves - General Design Criteria  
  • Floating Ball / Trunnion Mounted
  • Full or Reduced Bore
  • Manual Lever, Gear or Actuator Operated
  • 2 or 3 Piece Bolted Construction
  • All-welded Construction
  • Special Seat Design Options - Self Relieving / Double Piston Effect
  • Operating temperature and fluids suitability - further information on request
  • Firesafe / Cryogenic / Gas Service certified options
  • Modification service available for all stock options
Click for more Standard Pressure Class Ratings / End Connections
  • ANSI 800, 1500 & 2500lb - Threaded, Socket Weld and Butt-Weld ends
  • ANSI 150, 300, 600, 800, 1500 & 2500lb - Flanged RF, RTJ, Butt-Weld and Hub ends
  • PN, API and other Pressure Class Valves available on request

Common Materials of Construction Material Specifications
Standard Carbon Steel ASTM A105
A216 WCB
WCC
Low temperature Carbon Steel ASTM LF2
A352 LCC
LCB
Stainless Steel ASTM A182 F316
ASTM A182 F316L
ASTM A182 F304
ASTM A182 F304L
ASTM A182 F321
ASTM A182 F347
ASTM A351 CF8M
ASTM A351 CF3M
Specials F44
SMO
F51
Duplex
Super Duplex
Monel
Hastelloy
Titanium
Inconel
Bronze
Alu. Bronze
Other Actuated
Soft Seated
Metal-to-Metal Seated
Ball Valve