Severe Service Valve


This is a 3D model of a Choke Valve.

3D Model Annotations

Choke Control Valve

This valve is a type of choke valve used in high pressure and high velocity systems. The unique design of the valve plate stack reduces erosion of valve trim, reduces the risk of cavitation, reduces vibration, reduces the pressure drop across the valve, and reduces noise (due to vibration reduction).


The body forms the main pressure boundary of all valves and must be constructed from suitable materials to withstand the service pressure to which it will be subjected. It is often cast as a single piece, although it is possible to construct the body from several pieces.


Valves are often named after the type of disc they employ e.g. ball valve, plug valve etc. Discs may be linearly actuated (gate, and globe valves etc.), or rotary actuated (ball and plug valves etc.). This valve is linearly actuated.

Plate Stack

The plate stack consists of a series of plates pressed together to form a cylinder. Each plate is designed to provide a torturous flow path as the fluid flows from the inner to outer diameter of the plate. The torturous flow path reduces the velocity of the fluid as it passes through the plate, which reduces erosion of valve parts, and reduces the pressure drop across the valve.


The valve disc presses against the valve seat. It is imperative that the disc and seat surfaces remain clean. If the seat or disc surfaces are damaged, or not clean, it will not be possible to obtain a seal between the seat and disc; this will lead to the valve passing (leaking) when in the closed position.


The stem connects the actuator to the disc. Stems must be strong enough to withstand the mechanical actuation stresses they are subjected to during operation. Note that the stem for this valve is thin because smaller penetrations through the bonnet are desired; smaller penetrations are desired due to the large service pressure at which the valve operates.


Many valves require a bonnet. A valve bonnet allows personnel to access a valve’s internals (known as ‘valve trim’) without needing to dismount the valve. The bonnet is attached to the valve body using nuts and bolts (or studs). Gaskets are used to seal the space between the bonnet and body.


Flanges are attached to the valve body; they allow for associated piping to be attached.


Packing is installed between the stem and bonnet to ensure the valve does not leak. The packing gland can be periodically adjusted so that a constant pressure is maintained on the packing, which reduces the likelihood of leakage. Overtightening the packing gland makes the valve difficult to operate and may also lead to damage of the valve stem.

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