Next to rudimentary sluice gates, plug valves are the oldest valve technology known to modern times, dating back to Roman water systems. They have stood the test of time due to their simplicity and reliable service.
Plug valves are a rotary style valve similar in motion to a ball or butterfly valve (typically 90 degree rotation). There are several different types of plug designs including:
- Tapered sleeve plug valves (the closure member is a solid tapered plug with a rectangular hole through it. The tapered plug is wedged into the seating surface in the plug.)
- Eccentric plug (the closure member moves eccentrically in the body, where the plug does not contact the sealing surface until it moves into the closed position)
- Expanding plug double block and bleed (covered in a separate section)
- Lubricated plug valve (similar to tapered sleeve but with a grease lubrication to facilitate sealing, typically used only on natural gas service)
Plug valves typically have higher operating torques when compared to ball or butterfly valves, making them a great selection for manual applications, but perhaps less economical when automating.
The various plug valve designs exist to serve very specific industry needs and Spartan’s experiences technicians can help decide which technology may be best for you.