Dear all; please I want a clear ex

[Nemara]

Dear all;
please I want a clear explanation for the difference between Wafer, Lugged & double flanged butterfly valves & in what operating conditions to chose between these three types.
Thanks in advance for your feedback

 

[LittleInch]

Is this clear enough (Fange should read "flange"). Really didn't take long to find it....

Lugged tend to be used where they are quite heavy and where you don't want the valve to rotate, flanged where you want to isolate one side and remove the flanged pipe while the valve is closed.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Danlap]

Hi

In terms of internal design, not much different.
the question should be revised, what could go wrong if Wafer and Lug type are selected.
In oil and gas industry, and probably most industries try to imagine worst case scenario. What will happened in case pool of fire occurs? or what can go worng when valve about to be dismantled from the line? etc.

Wafer: a compact valve squeeze between two (Pipe) flanges with (normally) exposed bolts

https://en.wikipedia.org/wiki/Buncefield_fire

due to bolts elongated in the case of pool of fire

Lug: More or less same like Wafer type however the bolts covered by the body.
some design have tapped / threaded through hole. Imagine big size, under ground and bolts are corroded. it would take sometime to dismantle the bolts in places hard to reach by hands/cutting machine.
Unlike double flange, normally only one bolt used, there is also some risk attached to it.

I would say if the service inside the valve is not fire proof and prone for contributing larger fire, then aside from Water and Nitrogen services not suggested to use Wafer and sometime Lug type.

Regards,
MR

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[Nemara]

Hi Danlap,
Thanks for your feedback I really appreciate that's what I was looking for

 

[pennpiper]

LittleInch,
I think you switched the captions on the "Butt Weld Connection" and the "Lug Wafer Connection" images. Please consider editing your post

Sometimes its possible to do all the right things and still get bad results

 

[Danlap]

Hi Nemara,

You're welcome. Btw, just realize that I was using a very poor grammatical wordings and cannot edit my post (error on eng-tips forum?). Shame on me and for that, my apology.

Regards,
MR

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[LittleInch]

Ha, that's what I get for a crap photo from the web - not my drawing or picture sop can't edit, but a picture and 1,000 words etc...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.