Copper Union Leaking

[Rick Richardson]

This is my plumbing project from hell. I'm hooking up a
water softener and I need to use a union to allow me
to disconnect the softener from the rest of the plumbing.

I got a 3/4" copper union from Home Depot. The female side is
brass and the male side is copper. It appears to seal itself
by the compression of the metal against the metal. Both sides are
sweated onto 3/4" copper pipe. There are actually two of these,
one for the goes-into, and one for the goes-outta on the softener.

I've tried twice now, and I can't get the either union to make
a perfect seal. I've gotten out my really big wrench and
tightened those puppies down as tight as is humanly possible
and it still leaks. About 1 drop every 10 seconds or so.

On the second attempt, I put TFE pipe dope on the threads themselves
(but not the mating surfaces). But they still leak out the
top ring on the female side of things.

So whats the secret with these puppies? Does anybody have
any magic tips for making these seal perfectly? Should I
try pipe dope on the mating surfaces??? Is there some other
type of union I should get other than the copper unions they
sell at Home Depot???

Thanks in advance for any advice you might have.

-Rick

[Jim Mais]

Rick Richardson wrote:
>
> snip

>
> I got a 3/4" copper union from Home Depot. The female side is
> brass and the male side is copper. It appears to seal itself
> by the compression of the metal against the metal. Both sides are
> sweated onto 3/4" copper pipe. There are actually two of these,
> one for the goes-into, and one for the goes-outta on the softener.
>
> I've tried twice now, and I can't get the either union to make
> a perfect seal.

The leak occurs at the sealing surface, not the threads. Coat the
sealing surface (ground joint) with a little pipe dope or silicone
sealer. You don't need more than a little smear.
Speedy jim

[JBOBST]

Unions should seal with only normal tightening. You can't use them to pull
misaligned pipes into line or compensate for too short sections. The purpose
of a union is to connect two straight pipes of the correct length.
Overtightening will distort the softer part and it will never seal. Forcing
the fitting together will often scratch the sealing surface and promote leaks.
You may also have a little chunk of solder hiding somewhere (a mistake I have
to confess I have made). At any rate, be brave, do it over, and maybe you
might have beter luck with fittings from a real plumbing distributor. I have
noted a difference in DIY products and trade products in several instances.
JBO...@AOL.COM

[Phil Munro]

Rick Richardson wrote:
>
> This is my plumbing project from hell. I'm hooking up a
> water softener and I need to use a union to allow me
> to disconnect the softener from the rest of the plumbing.
>

> I got a 3/4" copper union from Home Depot. The female side is
> brass and the male side is copper. It appears to seal itself
> by the compression of the metal against the metal. Both sides are
> sweated onto 3/4" copper pipe. There are actually two of these,
> one for the goes-into, and one for the goes-outta on the softener.
>
> I've tried twice now, and I can't get the either union to make

> a perfect seal. I've gotten out my really big wrench and
> tightened those puppies down as tight as is humanly possible
> and it still leaks. About 1 drop every 10 seconds or so.
>
> On the second attempt, I put TFE pipe dope on the threads themselves
> (but not the mating surfaces). But they still leak out the
> top ring on the female side of things.
>
> So whats the secret with these puppies? Does anybody have
> any magic tips for making these seal perfectly? Should I
> try pipe dope on the mating surfaces??? Is there some other
> type of union I should get other than the copper unions they
> sell at Home Depot???
>
> Thanks in advance for any advice you might have.
>
> -Rick

I was not aware that pipe dope was ever good with unions. Be sure you
have a proper set of the pieces for the unions, and be sure there are no
scratches on the mating surfaces. They are intended to be a metal-to-
metal seal, but you need *TWO* appropriate wrenches to adequately torque
the union. Are you using two wrenches? If not, that may be the
problem -- insufficient tightness. Also, unions need good alignment.
If you do use dope, for it to help it would have to go on the mating
surfaces, not the threads. --Phil
--
Phil Munro Dept of Electrical Engineering
mailto:pcm...@cc.ysu.edu Youngstown State University
Youngstown, Ohio 44555