What are Plug Valves (w/ special guest Joe Exotic)

Today we are going to talk about the plug valve. The plug valve like a ball valve and butterfly valve is a quarter turn ball valve. So what does that mean?
it means to open or close the plug valve you only need to turn it 1 quarter of a full revolution. A fun fact with the plug valve, when open its called “full on” when closed its called “full off”
The head marks to the operator if the valve is open or shut with the port openings. If parallel it is open if opposite then closed.
Plug valves are made up of a stopper across a passage way.
The stopper is a plug with a hole through it. The hole is called the port. That can be rotated to align with the pipe openings. When the port is in alignment with the passage way the media can go through. When it is moved 90 degrees or as we mentioned a “quarter turn” , the passage way is closed.
There are two types of plugs in these valves that we will discuss. They are called either Cylindrical or tapered and have 2 different applications. So let’s compare the 2
the cylindrical plug has a Larger port opening, including the full pipe area. Will not bind due to pressure lock. However, they do have a shorter life span, as the plug received wear and tear the gap between the plug and body eventually leading to leakage. So cylindrical plugs are great for lower torque for a good seat seal.
The tapered has a restricted opening. Which can bind under large pressure differential. They do have a longer life with the tapered design helps the wear for the tapered plug can go in the body further and prevent the formation of a gap. The tapered plug has higher torque and better seat seal then the Cylindrical.
The two main types of Plug valves that we deal with in the industrial world are Lubricated and sleeved plug valves
Lubricated Plug Valves utilize an engineered sealant to lubricate and to aid in sealing. The lubricant in effect becomes a structural part of the Valve, as it provides a flexible and renewable seat.
the plug valve will need sealant made for the valve. This is not something you can roll over tot eh home depot and just buy the needed grease.
The sealant is injected into the cavity, and a Check Valve below the injection fitting prevents the sealant from flowing in the reverse direction.
Sleeved Plug Valves contain an elastomeric body liner or a sleeve (typically Teflon), which is installed in the body cavityThe sleeved plug acts like a floating ball valve and presses the plug against the sleeve and body forming a seal.
the plug valve like it’s quarter turn brethren is not recommended for throttling services.
did you know, that the first plug valves were used by the ancient Romans and made of wood. They were used to regulate water in rivers and streams for public use. During the Renaissance, Leonardo Da Vinci sketched how they could be a more sophisticated valve. And in 1705 the valve that we are now most common with was developed by Thomas newcomb to help regulate the first steam machine.
Joe exotic explains that Because of its large sealing area, these valves are great for tight shutoff applications and for highly corrosive or erosive and Gas line services.
advantages of using a Plug valve Quick quarter turn on-off operation, Minimal resistance to flow, Lubricated plug valves seat problems are easily repaired in line with the addition of grease.
Disadvantages are Requires a higher torque to open and close, due to high friction, Most have a reduced port, due to space constraints.

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