weld neck flanges in between 2 butterfly valves
weld neck flanges in between 2 butterfly valves
(OP)
Is there anything wrong in having weldneck flanges welded back to back and placed in between 2 butterfly valves? the space in between the flanges ranges in between 3 to 5 inches.





RE: weld neck flanges in between 2 butterfly valves
RE: weld neck flanges in between 2 butterfly valves
RE: weld neck flanges in between 2 butterfly valves
I've done this with low- and high-pressure applications, with both liquids and gas and never had a problem.
RE: weld neck flanges in between 2 butterfly valves
RE: weld neck flanges in between 2 butterfly valves
I'm pretty sure that there is enough offset within a RFWN flange that the flappers wouldn't contact each other so that isn't a problem.
Welding two flanges back to back is not illegal, immoral, or counter to any code that I know of, but if I was doing it, I'd put a pup between the flanges to have a place for a vent/drain/sensing point, but that is just because you can't ever have too many vents/drains/sensing points.
David
RE: weld neck flanges in between 2 butterfly valves
RE: weld neck flanges in between 2 butterfly valves
tks!
legs
RE: weld neck flanges in between 2 butterfly valves
I presume that you have two butterfly valves as one is for control and one maintenance isolation or for dual isolation for safety reasons. More detail would help.
Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng
www.waterhammer.bigblog.com.au
RE: weld neck flanges in between 2 butterfly valves
If it's process-related and Geoff is right with his guess about isolation, you might need a vent/drain between the two depending on the fluid/temperature/fluid (or any combination). Does the control valve (if it exists) fail closed?
Paul
RE: weld neck flanges in between 2 butterfly valves
Good point about the vent and drain.
I just realized that I recently comnpleted a project which resulted in the very scenerio that you have mentioned which required a vent and drain between the valves