Ball of trunnion ball valve is fixed, it does not move with medium pressure. Trunnion ball valve has floating seats.  The seats move with the medium pressure to tight the ball and seal ring to ensure sealing reliability. Bearings could be mounted in top shaft and bottom shaft, which reduces operation torque. This is widely used in valves with high pressure and big sizes. To decrease the operation torque and increase sealing reliability, lubricated ball valves are adopted in recent years. A special sealant is injected between sealing faces of lubricated ball valve to create a layer. This increase the sealing reliability while decreasing the operation torque, which is better for high pressure, big sized ball valves.

Sealant Injection Device

Trunnion mounted ball valves are provided with devices for Sealant injection, which are on both the stem and seat for the trunnion ball valves of DN>150mm (NPS6), and in the body cavity for the valve of DN<125mm. When the O ring of stem or the body seat ring is damaged due to accident, the medium leakage between body and stem can be prevented by injecting the Sealant through the device.

Double Block and Bleed

Trunnion ball valve features the front ball sealing design structure. Each seat of the ball valve can separately cut off the medium at both upstream and downstream to achieve double block function. When the ball valve is closed, body cavity is segregated from both upstream and downstream even there is pressure at both ends. The medium left in the body cavity could increase the pressure to propel the seats. The medium could be bled out through the relief valve to ensure valve safety.

Anti-static Design

Except for the anti-static features floating ball valve has, the trunnion ball valve has more. The ball of the trunnion ball valve gets close contact with each other through the trunnion, adjusting cushion, and down-end cap, the passage of static electricity thus forms together with the valve, which may lead the static electricity caused by sparks generated by friction between the ball and seat during on and off performance to the ground to prevent the possible  risk of fire or explosion. 

Fire Safe Design

With the valve heated in a fire application, the nonmetal material parts such as seat sealing ring of PTFE,O ring for the stem, and sealing gasket for body and bonnet, might be damaged due to high temperature. FBV's special design of auxiliary metal to metal or the graphite seal is designed for the trunnion ball valve to effectively prevent both internal and external leakage of the valve in case of fire As required by customers, FBV's fire safe design for the trunnion ball valve meets the requirement of API 607, API 6Fa and BS 6755.