Flange Globe Valve Structure

What is a flange globe valve?

A flange globe valve is a type of valve that uses linear motion to open and close fluid flow. It stops flow using a component known as disc. The valve is made from high-strength materials such as carbon steel and stainless steel, enhancing its strength for high pressure and temperature. This valve is connected to the fluid pipeline using bolts and nuts. It comes with flanges on both inlet and outlet ports. The flanges have holes to hold the bolts. This design makes the valve very strong for high-pressure and also helps prevent against impact damage from falling objects.

The design of these valves causes changes in the fluid flow direction, which leads to resistance and, thus, pressure drop. However, their design has the advantage that installation allows fluid flow through the seat and against the disc to prevent dirt and debris accumulation. Flange globe valve manufacturers recommend these valves for shut-off and throttling fluid flow, unlike other valves like gate valves designed for shutoff only. The valve uses a manual handwheel, pneumatic, electric, or hydraulic actuator.

Figure: Flange globe valve.

Components of a flange globe valve 

Valve body 

The valve body is the exterior component that covers the internal parts of the valve. It contains the inlet and outlet port flanges with holes for bolts to connect the valve to the pipe. The body is usually made of metallic material, and it is thick. The thick geometry enhances its ability to withstand internal fluid pressure and protect internal parts against impact damage.

Valve bonnet 

The valve bonnet is usually mounted on top of the valve body. The bonnet helps seal internal fluid pressure against the atmosphere and prevents the entrance of dirt into the valve. Both the body and bonnet are made from the same metallic material and mounted together using bolts and nuts.

Handwheel 

The handwheel is a manual actuator where the valve operator applies torque to start or stop the valve.

Stem 

Stem is a threaded shaft that connects the handwheel to the valve disc. It is responsible for transmitting power from the handwheel/actuator to the valve disc. It operates by converting rotary motion from the handwheel to linear motion on the disc allowing the disc to move up and down to open and close fluid flow respectively.

Valve disc 

The valve disc is the component that starts and stops the fluid flow. The handwheel powers the disc via the valve stem. There are three most common disc designs which are plug discs, ball discs, and composition discs.

Seat 

The seat is a component where the valve disc fits when it stops fluid flow. It helps to ensure a perfect seal of the disc and valve body to prevent fluid flow or leakage when the valve is closed. Flange globe valve manufacturers design the seats integrated into the valve body or screwed into the body as rings. Other valve designs have back seats on the bonnet to seal the stem and bonnet and thus prevent any leakage.

Packing 

Packing is a dynamic component that seals the stem to prevent fluid leakage from the valve. It also prevents contaminants and dirt entering the valve.

Figure: Components of a flange globe valve.