Replies

1. 
   mike4244 | Dec 27, 2005 08:46pm | #1

   I am not a plumber, I have done a lot plumbing though. Unions should not need anything on the face or the threads. The only time I had a union leak was from a bad union. The face apparently was not flat. If all your unions that leak come from the same supplier, try another brand.I do not use dope or teflon tape on the threads of unions, is it possible that the tape ,if you are using it is folding over on  the face?

   mike

1. 
   junkhound | Dec 27, 2005 09:04pm | #2

   One nice thing about copper unions is that I've never had one leak, surprised to hear any do. 

   The comment about having gotten tape or some such onto the mating surfaces is one possibility.

   Also: re -  I have tried to tighten them without ruining the sealing face, you DO need to tighten them enough so that the face deforms slightly, typically about 70 ft-# (50N-m) on a 3/4 copper union is what I use,  a limp 5 ft-# = leak. 

1. 
   Porsche998 | Dec 27, 2005 09:24pm | #4

   Will check the mating surfaces and try again

2. 
   Porsche998 | Dec 27, 2005 09:24pm | #3

   Thanks - Will check

2. 
   wookie | Dec 27, 2005 10:15pm | #5

   I use Laco slictite ( paste teflon ) on water unions. A very small amount, just a light coat. It just helps lubricate and seal I think its just the quality of fittings, I just automaticlly do it on all unions anymore no leaks. Also works great on under sink drain slip nut fittings a light coat around tube drain slide bevel washer down and tighten nut works 99.99% of time on problem connection.

1. 
   Porsche998 | Dec 27, 2005 10:53pm | #6

   This wasthe approach that I was planning on taking - I think that there is enough variation in the seating surface to allow some weepage.

1. 
   wookie | Dec 28, 2005 10:00am | #12

   Slic tite will work with variations on seating surfaces not defects such as a burr as mentioned. Just torque it properly the lubed surfaces will mate up no problem.

3. 
   Shacko | Dec 28, 2005 12:18am | #7

   The problem with unions is that they are not made that good anymore.Most come from overseas. What I do is put a little pipe dope on the threads and the face. Works.

4. 
   efix2 | Dec 28, 2005 03:15am | #8

   Just to add to the confusion:    LOL

   Whenever I install a union I take it apart first and check for dings on the mating surfaces.  If in doubt I hit it with a swipe of sandpaper (which I have out anyways).  Only takes a sec.

5. 
   xxPaulCPxx | Dec 28, 2005 04:11am | #9

   I just repiped my garage, and used 8 unions - 5 were 3/4" and 3 were 1/2".  I used the yellow Rector thread sealent, and only one leaked.  The leaking one was a very slow drip, and was fixed by tightening it a little more.

   It is very important to lubricate any fastener that has two theaded parts, like a bolt and nut or a pipe union.  The lubrication ensures that the metals don't gall and they achieve a more uniform torque.

   Rebuilding my home in Cypress, CA

   Also a CRX fanatic!

6. 
   4Lorn1 | Dec 28, 2005 04:15am | #10

   Re: " I have tried to tighten them without ruining the sealing face."

   Seems to me, based on what little I have gathered from plumbers, that you may not have them tight enough. These units take a whole lot of torque to make up permanently. Especially as they get larger. IMHO much more than most other fittings and more than most people think. Two long wrenches applied like you had OBL by the nuts.

   Yelling 'I want to hear you scream.' while you work the wrenches helps. Also helps eliminate unnecessary interruptions and complaints. 'I love my job. I am well paid' is also an option. Whatever works for you.

   I wouldn't worry too much about over tightening as long as the wrenches are properly adjusted and don't slip or distort the fitting. Make sure you get a good three-point contact on a pipe wrench to prevent excessive distortion. Up side if they fail they needed replacing anyway.

7. 
   plumbbill | Dec 28, 2005 07:03am | #11

   OK are they copper to copper unions?

   Or are they die electric unions?

   copper to copper is not a test of strength putting them together a small bur can drip really easy. Yes use a dope of some sort on the threads to lubricate (not seal) when assembling.

   Some emery cloth on face is a good idea but don't go overboard.

   If everything is right you should not have any leaks. Then again this is not a perfect world.

   Putting dope on mating surface will usually seal it -------but when the dope eventually washes out it will leak again.