flange gasket sizing

rtv

I have a leaking flange on the main just coming up from the boiler.
the 4 bolt flange is for a 3" pipe. When shopping for a replacement gasket
I find that they are for a 6" bolt circle with 3/4" holes the existing bolts appear
to be in a 5.18" circle and 1/2" bolt size. not sure if the larger holes in the new gasket would allow it to work or not. another interesting thing is it appears that there is a
a gap in the gasket at each bolt location (and a couple other places). It wouldn't surprise
me if the yahoo that installed the boiler tried to reuse an old broken gasket but i don't if there is some kind of gasket that's made that way. I would appreciate and thoughts or insights! Thanks

JUGHNE

Are you sure that is 3" pipe?

What is the circumference of the pipe?

Easy to measure with a tailor/seamstress/sewing tape. Wrap around the pipe.

SlamDunk

This maybe what you need.

https://www.mcmaster.com/9472K638-9472K141

Or something like it

rtv

slamdunk
thats exactly what i was looking at but was worried about the bolt circle size.

and JUGHNE
the pipe OD Dia. is 3.5"

JUGHNE

I am curious on how to remove the old gasket and get the flange surfaces clean.

If the top flange can be pried up some to get a scraper between the flanges then it is possible.

Not easy in any case unless you can get a grinder/brush on the flats.

Let us know please.

rtv

JUGHNE
that is not an issue for me as i can easily separate the two flanges by raising the upper pipe. (i think)

EBEBRATT-Ed

@rtv

That is not a standard "companion flange". What you have is a "flanged union".


The flanged unions are sold as two flanges and a gasket and the bolts. Don't know if you can buy the gaskets separately.


If you can it would be at a real piping/plumbing supply that deals with steam......not a HD or Lowes.

You could also make a gasket. Use a "garlock" gasket material which will work on steam. Avoid red rubber which will dry out and crack. Maybe McMaster Carr would have some steam rated gasket material

see page 47 of the attached

If the pipe is 3 1/2 OD that is 3" pipe. The gaskets for those are "ring" gaskets the gasket fits between the bolts....the bolts don't go through the gasket. The outside diameter of the gasket is the inside diameter of the bolt circle. Use never seize on the bolts and gasket available at an autoparts store

JUGHNE

Ed, I was trying to remember the term for "flanged union".
You mentioned this in another thread.

Then the challenge of unscrewing the old parts.

Eliminates the work of cleaning the old flange surfaces.

One could grind/saw the flange to get a piece of the pie out then unscrew it.

That ring gasket probably explains why he has a jacked up gasket in there.

rtv

EBEBRATT-Ed

Thanks SO much! that explains everything and totally fits with the people who installed the boiler.
also thanks for the fittings catalog I'm sure it will come in handy in the future. I had already looked at
Mcmaster for gaskets and gasket material they have lots of both!
Thanks again!

EBEBRATT-Ed

If you can spread the pipes far enough apart I would make a gasket if you can't buy one. I don't think I have ever seen those gaskets sold separately.

Or you can cut most of the way through the flanges with a grinder with a cutting disk just short of the threads drive an old screwdriver in the joint and it will crack apart since it is CI

rtv

I think (hope) i will be able to get the space by raising the top pipe and 5 or 6 in below the flange is a union which might help as well. Thanks!