A gate valve is an isolation valve that controls flow by raising or lowering a gate (wedge) between two seats. It is designed to operate either fully open or fully closed, providing tight shut-off and very low flow resistance. Luna Flow Control supplies gate valves in a wide range of materials, nominal diameters and pressure classes, suitable for service temperatures from -200 °C to +700 °C.
What Is a Gate Valve?
A gate valve regulates the passage of fluid by means of a gate inside the valve body. When it is correctly selected for the pipeline and the medium, it provides full sealing and protects the safety of the installation. Gate valves are suitable for both liquids and gases and allow flow in both directions.
Working Principle
The gate moves vertically, perpendicular to the flow, and seals against two seat rings. It can be of one-piece or multi-piece design. When the gate is lifted, the fluid starts to pass; when it is lowered, the passage is closed. Because the valve is intended for on/off service, it should not be operated partially open or used for fine flow regulation. In the fully open position the bore is unobstructed, so the pressure loss is minimal.
Types of Gate Valves
By connection
- Flanged gate valves
- Socket-weld and butt-weld (SW/BW) gate valves
- Threaded gate valves
By actuation
- Handwheel and gearbox operated
- Electric actuated
- Pneumatic actuated
- Hydraulic actuated
Common versions
- API gate valves – built to American Petroleum Institute standards for the oil and gas industry, with low flow resistance and minimal pressure loss.
- Bronze gate valves – handwheel-operated valves for hot and cold water, steam and various gases; durable and easy to maintain.
- Stainless steel gate valves – corrosion-resistant and leak-tight, widely used in the chemical industry.
- Flanged gate valves – a common choice for isolation duty, including lines carrying dense media.
- Forged steel gate valves – compact, robust valves for chemicals, hot water and compressed air.
- Electric and pneumatic actuated gate valves – for automated and remotely controlled systems.
Materials and Size Ranges
| Body material | Pressure rating | Size range |
|---|---|---|
| Stainless cast steel | PN 16 – 400 / CL150 – CL2500 | DN 50 – 1200 / 2″ – 64″ |
| Cast steel | PN 16 – 400 / CL150 – CL2500 | DN 40 – 1200 / 2″ – 64″ |
| Stainless forged steel | PN 16 – 400 / CL150 – CL2500 | DN 15 – 50 / 1/2″ – 2″ |
| Forged steel | PN 16 – 400 / CL150 – CL2500 | DN 50 – 350 |
| Alloy steel (F1, F11, F12, F9, F91) | PN 16 – 400 / CL150 – CL2500 | DN 40 – 600 |
| Duplex / Super Duplex | PN 16 – 400 / CL150 – CL2500 | DN 40 – 500 |
| Cast / ductile iron, non-rising stem | PN 10 – 25 / 125LB – 300LB | DN 40 – 300 / 2″ – 12″ |
| Cast / ductile iron, soft wedge | PN 10 – 25 | DN 40 – 300 |
Application Areas
Gate valves are used in oil and gas, petrochemical, chemical, pharmaceutical, manufacturing, automotive and marine industries, as well as in sewage and potable water networks, textile, metallurgy, energy pipelines and food processing. Typical duties include CO boiler outlets and electrostatic precipitator lines.
Advantages
- Tight shut-off with flow in both directions
- Very low pressure drop when fully open
- Wide temperature range from -200 °C to +700 °C
- Manual, gear, electric, pneumatic or hydraulic operation
Selection and Maintenance Tips
Select the body material, connection type, nominal diameter and pressure class according to the medium, temperature and pressure of the line; a valve that is not suited to the fluid will deteriorate over time. Use gate valves for isolation only – for throttling duty a globe valve is the better choice. Keeping the valve fully open or fully closed protects the gate and seats from erosion and extends service life.
