The different types of valves used in the petrochemical industry suit any of the following applications:
1. Start/stop the flow of the fluid (hydrocarbons, oil & gas, steam, water, acids) through the pipeline (example: gate valve, ball valve, butterfly valve, knife gate valve, or plug valve)
2. Modulate the flow of the fluid through the pipeline (example: globe valve)
3. Control the flow of the fluid (control valve)
4. Change the direction of the flow (for example a 3-way ball valve)
5. Regulate the pressure of a process (pressure reducing valve)
6. Protect a piping system or a device (pump, motor, tank) from overpressures (safety or pressure relief) or back-pressures (check valve)
7. Filter debris flowing through a pipeline, to protect equipment that may be damaged by solid parts (y and basket strainers)
knife gate valve
3 way ball valve
pressure reducing valve
basket strainers valve
VALVE BY DESIGN
GATE VALVE:This type is the most used in piping and pipeline applications. Gate valves are linear motion devices used open and close the flow of the fluid (shutoff valve). Gate valves cannot be used for throttling applications, i.e. to regulate the flow of the fluid (globe or ball valves should be used in this case). A gate valve is, therefore, either fully opened or closed (by manual wheels, gears or electric, pneumatic and hydraulic actuators)
GLOBE VALVE:This type of valve is used to throttle (regulate) the fluid flow. Globe valves can also shut off the flow, but for this function, gate valves are preferred. A globe valve creates a pressure drop in the pipeline, as the fluid has to pass through a non-linear passageway.
CHECK VALVE:this type of valve is used to avoid backflow in the piping system or the pipeline that could damage downstream apparatus as pumps, compressors, etc. When the fluid has enough pressure, it opens the valve; when it comes back (reverse flow) at a design pressure, it closes the valve – preventing unwanted flows.
BALL VALVE: A Ball valve is a quarter-turn valve used for shut-off application. The valve opens and closes the flow of the fluid via a built-in ball, that rotates inside the valve body. Ball valves are industry standard for on-off applications and are lighter and more compact than gate valves, which serve similar purposes. The two main designs are floating and trunnion (side or top entry)
BUTTERFLY VALVE:This is a versatile, cost-effective, valve to modulate or open/close the flow of the fluid. Butterfly valves are available in concentric or eccentric design (double/triple), have a compact shape and are becoming more and more competitive vs. ball valves, due to their simpler construction and cost.
PLUG VALVE: Plug valve is classified as a quarter-turn valve for shut-off applications. The first plug valves were introduced by the Romans to control water pipelines.
SAFETY VALVEA safety valve is used to protect a piping arrangement from dangerous overpressures that may threaten human life or other assets. Essentially, a safety valve releases the pressure as a set-value is exceeded.
Y-STRAINERS while not properly a valve, Y-strainers have the important function of filtering debris and protect downstream equipment that may be otherwise damaged