How do you seal up a copper union (water plumbing)

[rbattelle]

So I've got a union I'm using in my house water system as part of an attachment for a water softener. This is an all copper sweat fitting with a cast bronze nut.



What's the best way to get it to stop leaking? I've been trying teflon tape wrapped over the threads and over the nipple to no avail (so far).



I've had success getting them to stop leaking on other jobs, but this one has me frustrated.



I know they're "supposed" to seal at the copper seat, not at the threads, but I've never had one seal up without some kind of sealant. [I've plumbed in about 1/2 a dozen in my "career"]. The seat and nipple are polished clean with fine steel wool until they shine.



What do you guys do?



Ryan

 

[GHarman]

So I've got a union I'm using in my house water system as part of an attachment for a water softener. This is an all copper sweat fitting with a cast bronze nut.



What's the best way to get it to stop leaking? I've been trying teflon tape wrapped over the threads and over the nipple to no avail (so far).



I've had success getting them to stop leaking on other jobs, but this one has me frustrated.



I know they're "supposed" to seal at the copper seat, not at the threads, but I've never had one seal up without some kind of sealant. [I've plumbed in about 1/2 a dozen in my "career"]. The seat and nipple are polished clean with fine steel wool until they shine.



What do you guys do?



Ryan

I dope the sealing, mating surfaces with teflon pipe thread sealant, the gooey, stinky stuffOo. . Havent had one leak, yet. Its good to use it on the threads just to keep 'em from gauling. GregH

 

[GHarman]

PS when you put one of these together. Use Two wrenches and back up the male side of the union. That way the torque is concentrated on/in the work zone. GregH

 

[p-Bar]

Ryan most this stuff is made in China so we know what the Q. C. is like. Has this been mated before with no leaks? If it's new I would go buy a new one and use some valve lapping compound on it before you solder it up. Just my . 02

 

[HOBrian]

Ryan, tell me about it!!!

I had a water heater poop the bed not to long ago and had one heck of a time getting the union to stop leaking! I got it to only drip once every 5 minutes. The next day it had stopped all by itself. I cranked the **** out of the fitting, it just kept on turning which to me tells me that I crushed it and was lucky it stopped leaking.

 

[AClayton]

If tightened to the normal specs and it did not seal,you should just change the union and be done with it. Over-tightening rarely works and when it does,it doesn't last long before leaking again. The threads are merely for tightening... . the seal is through the mechanical connection between the similar metals. If sanded clean and polished as you stated... . it is the mechanical connection that is out of round or scored to some extent,causing your leak.



Alan

 

[rbattelle]

Well guys, I think I got her stopped up. Didn't change unions (it was a brand new one, by the way, but I'm not sure of the country of origin).

I used my old standby - plumber's putty. My goodness, that stuff has got me out of more jams than I can count. A small bit of it applied across the center of the union, then tighten it up with 2 wrenches.

I think I've used that same method on every other union I've plumbed, and they've held solid for over 3 years now.

Keep that in mind, Brian - plumber's putty. I know it's supposed to be for setting sinks and faucets, but it's just clay. Non-toxic.

A few years ago I too installed a new water heater. Couldn't make the fittings stop leaking. On that job, I ended up using BOTH plumbers putty (smeared into the threads) and Teflon tape (over top of the putty).

I HATE leaks. They keep me up at night. Literally. I've diagnosed myself with "Plumbing Phobia". Ever since my entire house (literally) was destroyed (almost a total loss) by a leak that occurred while no one was home.

Ryan

 

[HOBrian]

Ryan, I never would have even thought of using plumbers puddy on it. Thanks!!!

I had trouble sleeping at night with it dripping too!



Short story... My parents house has a well and one fitting was leaking and Dad being cheap let it drip into a bucket. (one drip ever 5 minutes) We went on vacation for a week in VT. I brought the cooler in from the garage down into the basement where I was met by TWO feet of water. That drip got so bad it broke the pipe and the well pump just kept running!!:{ Fitting $4. 10 making fun of Dad being cheap priceless!!:-laf

 

[rbattelle]

Best bit of advice I know - when you're leaving your house for more than a day, shut off the water main (or unplug the well pump).

Ryan

 

[nickleinonen]

i usually now lap all the unions i use. the hard ones for me to get to seal are the solid steel ones with no brass seat that are rated at +3,000psi. they frustrate me. last one i could not get the drip to stop so i found a proper sized o-ring and put it around the seat. so the mechanical joint is holding the pressure and the o-ring is holding back the 1 drop/10 min it had. i spend half a shift yesterday lapping and grinding valves, checks and unions so i can fix up the leaks on the 300hp cleaver-brooks boiler so i can get it online and shut down the noisy volcano boilers. . yeah plumbing can be a nightmare at times. and back in feb i was called to work to fix a 1" water line that broke at just after 2:00am. . 1" @ 80psi it a lot of water. fixing it at 3:00am on 2 hours of sleep is no fun

 

[rbattelle]

I've got a leak now at a threaded fitting (not a union - a 3/4 NPT fitting into the water softener) that is "sweating". It gets a single wet spot (not even enough to actually drip) over a period of 24-48 hours.

I keep hoping it'll stop on it's own. Not sure when to decide to dismantle and reseal.

Ryan

 

[GHarman]

Ryan, Is it sweating from the high humidity and 90+ degree temperature air coming in contact with a cold water valve? If there is an orifice (Valve) where pressure of the transfer of a liquid is changed even slightly, the temperature on the low pressure side will be colder. If that valve seems colder especially after using water for a dishwasher or clothes washer (lots of volume) you should notice sweating at any reduction of size of your cold water piping system. Dry it, then run the washing machine. Observe! IMHO. Something to consider, Remember K. I. S. S. . Identify the leak before dissassembly. GregH

 

[GHarman]

Ryan, Did you determine, for sure, wether or not you have a leak? GregH

 

[rbattelle]

Yeah, it's a leak. The world's slowest leak. A TINY drop of water forms every 24 hours or so.

I'm going to leave it alone.

Ryan

 

[GHarman]

Good IdeaOo. ! Just keep an eye on it. Things like that are a real Pain. GregH

 

[Dieselnut59]

Best bit of advice I know - when you're leaving your house for more than a day, shut off the water main (or unplug the well pump).



Ryan

I have animals in the barn with automatic drinkers, so I cannot shut off the well pump, but if I am gone for more than a couple days, I do turn off the supply to the house. When we installed my well, we set up a "distribution manifold" at the outlet of the bladder tank. There are separate shut off valves for the house, barn and shop, plus a faucet and long hose in case I have to shut one of the above sites off for repair. It is a lifesaver, as long as the well pump does not kick the bucket! It is 400 feet down!

I learned this lesson when we went on vacation when I was a child. Came back and a water pipe had broken, flooding the entire basement in almost a foot of water. Turn off your water supply when you leave for more than a day or so... and turn down your water heater.