Waht is Wedge Gate Valve and Its Structure

What is a wedge gate valve?

A wedge gate valve is a type of gate valve that uses a wedge-shaped gate to control fluid flow. The valve body is designed with a tapered hole so that the wedge-shaped gate can perfectly mate the edges leading to a perfect closure against fluid flow. The valve moves the wedge gate up and down to open and close fluid flow. The gate’s motion is linear and best suited for open and closed fluid flow applications. Wedge gate valves are widespread in the market due to their low-pressure drop in various industrial applications. These valves are not used in throttling applications because the gate can get damaged if partially opened. Also, high fluid flow velocity causes erosion on the gate surfaces and seats, leading to vibration and noise when the valve is partially open. Wedge gate valve manufacturers design these valves to be operated either manually or using electrical, hydraulic, or pneumatic actuators. The manually operated valves use a handwheel to open/close.

Figure:  Wedge gate valve.

Components of a wedge gate valve

Actuator

The actuator is the component that operates the valve. It is usually a manual handwheel or electric, hydraulic, or pneumatic actuator. For the manual actuator, the valve operator applies rotary force on the handwheel to either start or stop fluid flow.

Stem

Stem is a threaded component that connects the actuator to the wedge disc. The stem is meant to transmit power from the actuator to the valve disc to open or close fluid flow. When the stem moves upwards, it opens fluid flow; when it moves downwards, it stops the fluid flow. Wedge gate valve manufacturers produce the stem from high-strength metals such as stainless steel and carbon steel to ensure the high strength needed to operate the valve, especially for high-pressure applications.

Disc

The disc is the component that is connected by the stem. It can start or stop the fluid flow from the actuator via the stem.

Seat

Wedge gate valve manufacturers design the valve with two seats. The seat is a component that seals the valve disc to the valve body. The seats are made as rings or integrated into the valve body. They are either resilient or metallic. The resilient seats are made from soft materials like rubber or plastic and used where the valve is meant for low temperatures below 65o C. The metallic seats can withstand high temperatures, and thus they are suitable for temperatures above 65oC.

Valve body

The valve body is an outer part of the valve that houses the valve disc and the seats. Wedge gate valve manufacturers design the body from high-strength materials like stainless steel and carbon steel to ensure the body is strong enough to withstand high pressure and impact damage. The valve inlet and exit ports are made on the valve body.

Bonnet

The valve bonnet is usually mounted on top of the valve body. It is meant to cover the opening of the valve body and internal parts such as the stem and the valve packing. The use of welding, bolts, threads, or pressure seals connects the body and bonnet. Wedge gate valve manufacturers produce the bonnet and the body from the same material to enhance uniformity and also to ensure that the valve withstands high fluid pressure.

Packing 

Packing is a string sealant that prevents fluid leakage between the valve stem and bonnet. It also helps to control the entrance of contaminants and solids into the gate valve.

Figure: Components of a wedge gate valve.