Types of butterfly Valve

[sks4338]

There are several types of butterfly valve, lug type, single flanged type, double flanged type, wafer type.

The questions are as follows.
1. When do you use lug type?
2. When do you use wafer type?
3. When do you use single flanged type?
4. When do you use double flanged type?

 

[StoneCold]

I will give this a shot.
I choose lug type when I want to be able to loosen one side of the valve and maintain a seal on the other side.

I choose wafer style if I don't need the option to be able to remove one side, or if budget demands it.

I have never used single or double flanged butterfly valves.

Regards
StoneCold

 

[Ashereng]

We use wafer or double flanged only.

We use wafer when trying to reduce costs, and when the client allows.

We use double flanged on all other applications. It is our norm to flange all valves.

I have yet to specify a lug type, or single flange.

 

[JStephen]

What's the application?

In waterworks service, they have butterfly valves with long or short body. The difference being that the short body can't be opened when bolted up to a blind flange- it extends beyond the flange faces when opened.

 

[Oldliar]

Normally, a butterfly valve is wafer and then either lugged or flanged. If fully lugged (not only the two/four lugs for centering), it can either be bolt-through or double bolted, ie bolting from each side; this will give the same effect as a flanged valve. So, in a normal case, a single flange will be a fully lugged valve.

Just wondering, what's the case with the blind flange downstream a butterfly valve - and why do you need to open the disc towards a blind flange? (thus using long body) -I'm no waterworker, so it may be something here.

 

[JLSeagull]

Consider lugged and flanged butterfly for hazardous fluids such as hydrocarbons and chemicals. Wafer valves are normally installed with through bolts. In the event of a fire, the bolts can expand and the fluid can leak around the valve and feeds the fire. Thus, a prudent person avoids wafer valves in such service. As others suggest, the bolts and cap screws for flanged and lugged valves may permit disconnecting piping from one-side without removing the valve.

 

[11echo]

We use threaded lug type on tank nozzles. We put a hex. hd. bolt on the backside of nozzle with the bolt length just long enough to engage 1/2 of the lug, same for the front side. That way we can disassemble the piping, but keep the butterfly vlv. in place and holding back the commodity in the tank. You could use a stud to do this, but if you use bolts the mating piping portion can be slid off the vlv. as apposed to pulled off. OF COURSE we only do this on commodities that don't pose a hazard!!! Good luck

 

[Jankog]

Use flanges whenever there is a chance that a threaded connection can get damaged and forces you to throw away the equipment with the damaged thread.

It is very painfull to have to throw away a million dollar vessel because the thread the valves was supposed to attach to was damaged by a grain of sand or a stupid worker and now you can no longer seal it.

 

[Ashereng]

Jankog,

I would try to replace the damaged nozzle, or add another nozzle to the million dollar vessel, before throwing it away.

Threads get stripped, seize up, damaged.