Trunnion Mounted Ball Valve

Trunnion mounted ball valves are generally manufactured with the features of double block and bleed (DBB), cavity relief, bi-directional, fire safe and secondary metal to metal seated etc.

Trunnion mounted ball valves are made of carbon steel, stainless steel and low temperature carbon steel and duplex steel for oil & gas, and power generation industries.

As one of the reliable trunnion mounted ball valve manufacturers in China, Relia supplies Trunnion mounted ball valves wchich are designed and manufactured as API 6D, API 608 or other international Standard as client request. All the Trunnion mounted ball valves are 100% under hydrualic and penumatic test before leave the factory.

Standard Specifications

Product Range

Design Features

Fire Safe

Fire safe design is as per API 607/API F6A, to ensure the valve leakage test meet the standard request even after fire test.

Double block and bleed (DBB)

Double Block: When the ball is in the closed position, each seat seals off the process medium independently at the same time between the up/down stream.

Bleed: When the ball is in the closed position, any trapped liquid that might vaporize and expand can then do so at no greater than upstream line pressure. In a trunnion mounted ball valve, if the cavity pressure gets much above the line pressure, the spring-loaded seats should relieve the pressure before the valve is damaged.

Typical application: Pipeline ball valves in liquid services, to prevent pressure buildup in body cavity due to change in temperatures.

Self Cavity Relief (Self Relieving Seat)

Trunnion mounted ball valves constrain the ball by bearings. It is only allowed to rotate, but the seat can move. It also traps the media in the cavity when the operator closes the valve. It isolates the pipeline and the body cavity in the open and closed position. Thus, the pressure caught in the body cavity might be different from that in the line. The pressure increases in the cavity when heated. It pushes the ball seat of the downstream side away from the ball by rising pressure against the spring load. When this happens, the pressure gets released.

Secondary Metal to Metal Seat Design

Standard seat design is primary soft seal, and secondary metal to metal seal. Seat insert is designed as pressed-in type which is easy for maintenance. Optional design with primary metal to metal seal and secondary soft seal seat design is also available upon request.

Double Piston Effect Seats-(DPE*DPE) Optional

DPE seats are designed to be pushed against the ball in both cases, whether pressure comes from body cavity or from upstream/ downstream side. Ball valve with DPE seats cannot perform cavity relief. For such reason -in liquid services- the use of a relief valve is recommended.

Typical application: Whenever it is necessary to create an additional safe barrier between the upstream and the downstream sides. Recommended in welded body valves, where seats maintenance is notforeseen.

Combined SPE-DPE (Optional)

Upstream SPE seat ensures self relieving capability, while downstream DPE seat grants the double barrier in case of upstream seat damage. This configuration involves a preferred direction of installation with SPE seat facing upstream. With SPE-DPE configurations, cavity relief always takes place through SPE seat.

Typical application: Riser valves, pig launchers/receivers. DPE seat gives double isolation to the pig trap, allowing automaticrelief of body cavity at the same time in case of pressure build up.

Emergency Sealant Injection System

Each ball valve of size 6” and larger (or smaller size on request), is equipped with sealant injection located at stem and seats area. The injection is integrated with check valve to provide backup sealing, also a check valve is equipped at front of seat sealant injection to avoid blowing out in case wrong operation. When the soft sealing materials (seat inserts and o-rings) are damaged and leakage happened by fire or other accident, the sealant can be injected through the injection fittings.

Blow-out Proof Stem

The stem is made separately from the ball with integral T-type round shoulder, retained by gland.

Anti-static Device

Spring plus graphite type anti-static device are applied between the ball, stem, gland flange and body, to keep the electrical continuity between all the metallic components, and ensure the resistance lower than the most severe service requirement.

Typical Drawings

Material Specifications