Author	[Modern View]
Steve-Maine 11-30-2012 01:55:56 24.31.137.183 Report to Moderator	I have been running a 3/4" copper air line in my shop. I can"t seem to get the 3/4" copper unions to stop leaking. They are leaking around threads not solder joints.I bought Nico brand at HD made in USA. Would teflon tape and paste help?? Thanks for any help.. [Reply]   [No Email]
Dean Olson 12-01-2012 06:23:28 98.196.66.64 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Steve-Maine, 11-30-2012 01:55:56   I was taught to use pipe dope on mating surfaces and threads of unions as an apprentice plumber 30 years ago. We tested all systems with air before turning water or gas on. I remember very few leaks and never a problem with unions other than not getting them tight enough. Nico or did you mean Nibco. Nibco is the preferred brand of copper fittings. [Reply]  [No Email]
Mike (WA) 11-30-2012 08:15:00 69.10.199.107 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Steve-Maine, 11-30-2012 01:55:56   You don't really need unions with sweated copper- just "unsolder" a joint if you need to take it apart. [Reply]  [No Email]
showcrop 11-30-2012 15:45:24 75.67.231.80 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Mike (WA), 11-30-2012 08:15:00   Quoting Removed, click Modern View to see Ever work with copper? [Reply]  [No Email]
circus 11-30-2012 07:06:02 72.251.63.108 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Steve-Maine, 11-30-2012 01:55:56   "Would teflon tape and paste help??" Yes [Reply]  [No Email]
showcrop 11-30-2012 05:08:57 75.67.231.80 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Steve-Maine, 11-30-2012 01:55:56   I would have a problem with a union seating once in a great while. I always had silicone grease in my box so I would smear a dab on one side of the mating surface, which enabled it to seat a little better, and almost always stopped the leak. [Reply]  [No Email]
glennster 11-30-2012 10:00:57 75.57.134.154 Report to Moderator	Re: Problem with 3/4 copper unions in reply to showcrop, 11-30-2012 05:08:57   if you are going to use the airlines for spray painting, i would not use silicone. it will cause fish eyes in the paint. [Reply]  [No Email]
Ken Macfarlane 11-30-2012 04:57:31 142.166.168.2 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Steve-Maine, 11-30-2012 01:55:56   The threads on a union don't hold in the pressure, they just draw the mating surfaces together. Don't put paste or tape on them. You can lube the threads to make it easier to tighten. Open up the union, see if there are burrs on the bell or boot (right terms? the convex and concave mating surfaces). They also can't have misalignment. You need to crank them down tight for air service. In my old shop I replaced them with straight couplers. No leaks after that, could leave the compressor valve open. [Reply]  [No Email]
Brian G. NY 11-30-2012 08:43:29 64.22.46.132 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Ken Macfarlane, 11-30-2012 04:57:31   Ken is correct.......I have noticed that the China made plumbing "fittings" just don"t "fit" like the old USA fittings. [Reply]  [No Email]
Steve-Maine 11-30-2012 11:06:23 24.31.137.183 Report to Moderator	Re: Problem with 3/4 copper unions in reply to Brian G. NY, 11-30-2012 08:43:29   To Mike, I should have used connectors in the beginning. Everyone of the unions leaked. I'm now in process of cutting them out. Thanks Steve [Reply]  [No Email]