A valve is a device used to regulate, control, or direct the flow of fluid within a system or process by opening, closing, or partially obstructing it. In piping, many different types of valves are used in varying applications. Valves have an important role within piping systems and often account for up to 30% of the overall piping system costs. However, choosing the wrong type of valve for your system can increase costs markedly, making valve selection as essential to the economics of your system as it is to the operation.
The first and most common type of valve is the gate valve. These are linear motion valves used to start or stop fluid flow. During operation, the gate valve is either fully open or fully closed. They are used in nearly all fluid services including air, fuel gas, feedwater, steam, lubricant oil, hydrocarbon, and more.
The globe valve is a type of valve used to stop, start, or regulate fluid flow. These are frequently used in systems where flow control is required but leak prevention is also critical. They provide better shut off than gate valves, but are also more expensive.
Check valves are used to prevent backflow of fluid in a piping system. The pressure of the fluid passing through a pipe opens the valve, while any reverse flow closes the valve.
A plug valve is a quarter-turn rotary motion valve that utilizes a tapered or cylindrical plug to stop and start fluid flow. They are used as on-off stop valves and are capable of providing bubble-tight shut off. As such, they can be used in vacuum and other high-pressure and high-temperature applications.
Ball valves are another type of quarter-turn rotary motion valve, but these use a ball-shaped disk to control the flow. Most ball valves are of the quick-acting type, which require a 90° turn to operate the valve. Ball valves operate similarly to gate valves, but are smaller and lighter.
A butterfly valve is a quarter-turn rotary motion valve that can stop, start, or regulate flow. This valve features a short, circular body and a compact lightweight design, making it ideal for large valve applications due to the fact it takes up very little space.
Needle valves have a similar design to that of globe valves, but feature a needle-like disk. They are designed to provide accurate flow control within piping systems with small diameters. Their name is derived from their pointed conical disc and corresponding seat.
Also known as clamp valves, pinch valves are linear motion valves used to start, regulate, and stop fluid flow. They utilize a rubber tube known as a pinch tube, and a pinch mechanism that regulates flow. Pinch valves are frequently used to handle liquids with significant amounts of suspended solids or in systems that pneumatically convey solid materials.
Pressure Relief Valves
These valves, also known as pressure safety valves, are used to protect equipment or systems from overpressure events or vacuums. They are designed to release pressure at a predetermined setting to prevent these from occurring.