What are Ball Valves?
A ball valve is a valve that opens by turning a handle, gearbox or other actuation methods attached to a ball inside the valve. The ball has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends of the valve, and flow is blocked. The handle or lever will be inline with the port position letting you "see" the valve's position, position indicators will be applied to gearbox or actuators when required. Ball valves are durable and usually work to achieve perfect shutoff even after years of disuse. They are therefore an excellent choice for shutoff applications. There are two type of ball valve based on the ball type, floating ball valve and trunnion mounted ball valve. Depends on the bore size, ball valve is separated into full port ball valve and reduced port ball valve. There are three type of body styles of ball valve: one-piece, two piece split, three piece split, top entry and welded, FBV ball valves are available in two piece split, three piece split and welded.
The blow-out proof design has been adopted for the stem to ensure that even if the pressure in the body cavity is raised accidentally and the packing flange breaks, but the stem may not be blown out by medium. The stem features the design with a backseat, being assembled from underneath. The sealing force against the backseat gets higher as the medium pressure becomes higher. So the reliable seal of the stem can be assured under variable medium pressure.
V type packing structure has been employed to effectively transform the pushing force of the gland flange and the medium pressure into the sealing force against the stem.
Based on customers' requirement, a packing tightening design may be employed to obtain more reliable stem packing seal, which is loaded by bevelling spring.
Blowout Proof Stem
Blow-out proof structure is designed to avoid stem blow-out due to accidental medium pressure rise. The stem is positioned by screwed up-end cap.


Locking Mechanism
To prevent mis-operation, the fully opened or closed position of the valve can be locked up, especially when the valves are mounted outdoors or when valves are not allowed to be opened or closed by unauthorized person. A lock hole on the pad is designed for the lock purpose.


Mounting Bracket Provided
FBV has provided for ball valve with a mounting bracket, through which it is easy to mount a operation device like worm gear, pneumatic and electric actuator etc.


Trunnion Ball Valve

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.


Floating Ball Valve


A floating ball valve is a valve with its ball floating (not fixed by a trunnion) inside the valve body, it drifts toward to the downstream side and tightly pushes against the seat under the medium pressure to ensure sealing reliability. The floating ball valve has simple structure, good sealing performance but the seat material is required to withstand the workload since the sealing pressure is bared by the seat ring. Due to unavailability of high performance seat material, floating ball valve is mainly used in middle or low pressure application.

Design Features
Reliable Seat Seal


برای دیدن این تصویر بر روی آن کلیک کنید The structure design of double-beveled sealing ring has been adopted to reduce the friction between the ball and the sealing ring to achieve lower operation torque. When the medium pressure is low, the ball has smaller contacting surface with sealing ring, which introduces higher sealing pressure to ensure the sealing reliability. When the medium pressure gets higher, the contacting area between ball and sealing ring increases accordingly. Larger contact area reduces the sealing pressure to avoid the deformation of sealing ring.

Fire Safe Design

In case of fire, non-fireproof material for packing and seat will be burnt-out and considerable medium leakage may possibly cause fire spread. FBV adopted metal to metal seal as auxiliary structure to prevent medium leakage in case of fire as shown in figures. The fire safe design confirms to the requirements of API607, API 6FA and BS 6755.



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