Flange Adapter

[Chris73]

Hi Eng's!
Just a practical question: on a 10" line with meter and valves I want to use a Flange Adapter (UNIFLANGE) as provision for disassembling the items. So there is a short pipe spool with flanged ends - one flange would be a welding neck flange and one would be a flange adapter. Does that one adapter flange is good enough to provide a sufficient gap for taking the pipe spool piece out and back in, with the both gaskets for both flange ends? I have seen people using adapter flanges at both ends - is that necessary? Thanks!

 

[electricsub]

Hi Chris,
If you follow Uniflange installation instructions, you will be able to remove your inline valves & meter and replace with a spool piece. Check that the spool piece length is just short of the neck of the flange adapter, makes it easier to fit and remove.
By neck distance i mean the length inside the fl. adatper to the neck, which is just in front of the gasket.
If the valves etc have been in a long time and on say a sewage/wasterwater application it can be difficult dismantle, takes time and a bit of cursing but eventually the fl. adapter will come off.
Clean it up and you may be able re-use it, although manufactures may not agree, but we have many many times.

Good Luck
Bob

 

[BobPE]

Chris:

I have used them but prefer to put a smith-blair coupler in line somewhere, it give the maint people a lot more room to work with.

BobPE

 

[bhwtam]

Chris73,

Putting one flange adaptor will surely give you enough clearance to remove the valves and the meter. I didn't get the catalogue with me but I think a 10" flange adaptor will give you a clearance of at least 38mm.

Why sometimes we put two flange adaptors? Not because for the clearance, but is for pipeline alignment. Other than offering clearances, flange adaptors also offers an angle displacement (~15 deg), so if your pipeline is misaligned a bit, you can use the flange adaptors to make the adjustment. This can be found easily in valve/meters pit where the two puddle pipes are always misaligned.

Just another note: Flange adaptors are fixed to the pipe (spool) with its wedged rubber ring. Try to avoid asking it to withstand any thrust or it will comeout. Use "tie-rods" if necessary.

 

[Chris73]

bhwtam;
I think you have a flange adapter like Smith-Blair 912 mind. In order to save some room I would like to use the Uniflange version, which is slimmer. Further the flange is fixed with set bolts to the pipes outside. At least Uniflange promises a 'built in thrust restraint' with that. I don't know if I would rely on that (any experience with that out there?) but in my case I won't apply much thrust to the flange. Uniflange gives a max. distance of 6 mm to the mating flange - so I am not quite sure if that gives me enough play for disassembling the 10" flanged pipe spool (concerned about the re-installation of the flange gaskets!)

 

[bhwtam]

I think 6mm clearance is not enough for your re-installation as the gasket will not be totally flat when you put it in and once it touches the side of the flange, it won't go in any more.

 

[dicksewerrat]

On one side of the spool piece use a mech. joint coupling. cut the pipe an 20-25 mm shorter than it should be. Then you can loosen the other end of the flange piece and move it for clearance. Your joint config. will be downstream flange, upstream flange and mech joint. you should put in tie rods for stability under working pressures.