The ball is mounted on trunnions supported in body bearings above and below the ball. Sealing is achieved by spring loaded piston type seats which shut off flow when the line pressure acts on the upstream seat. This design provides automatic relief of cavity overpressure. The standard design cannot be used for double block and bleed isolation duty but "twin seal" designs are available which can, although they would seldom be first choice for such a service.
In this case, automatic cavity relief is forfeited and an external relief valve must be provided if this ia a requirement.
|Valve Design||Side entry, Top entry|
|Trim Design||Trunnion ball|
|Size||2" - 36"|
|Pressure Range||150# - 2500#|
|Design||ASME VIII or B 16.34|
|Bore||Full or Reduced|
|Materials||Carbon Steel, Stainless Steel, Duplex, Super Duplex|
Conform To NACE MR 01-75
|Material Status||Forged or Cast|
|Seats||Soft or Metal|
|Seals||O-Rings or Lip-Seals|
|Testing||API 598 - API 6D|
|Operator||Wrench, Gear, Actuated|