Copper and Brass Unions leaking, could use sanity check.

[AirOp]

What can I do to fix a leaky tapered union? (copper or brass) On dielectrics I know I can use a new washer...
UPDATE: Bigger Wrenches seems to have worked! (_way_ more that 50ftlbs)

Here are things I tried:
1: lap with toothpaste? (spun) didn't help
2: evaluate mating surface with bluing or marker? (very little rubbed off)
3:tighten righteously? (tried, but heard I shouldn't have to)
4:tap wiggle to ensure alignment (tried)
5: search youtube I'm at wits end, and youtube only shows some guy using shark bite couplings, and the internet searches only have people doing goofy things with teflon tape.
6: Replace union (only replaced once, the second one was much better, but still leaks about a drip every 5 minutes)

Things I have not tried:
teflon tape (seems wrong)
pipe dope (seems wrong)
annealing the copper (perhaps I overheated the fitting and cooled it quickly?) ( would I have to disassemble a bunch of stuff? and then deal with resoldering fittings? )

I confirmed that my solder joints are not the leak.. But I may have changed the copper properties in error.

7. (What worked) Bigger Wrenches! I bought 2 15in adjustable wrenches that could get the 1.5in nut (rather than my pipe wrenches that were marking the nut) It was in an awkward position, but I still had enough space, I didn't quite go to the point where I was scared, but it was much tighter than I expected to go.

more details:

I switched from a propane torch to map and a bernzomatic 8000.


My use is to attach a heat exchanger in a closed loop system. the heat exchanger has 4 male 3/4in threaded attachment points all facing the same direction. I plan to use flexible copper for most connections, but the connection from the circulation pump will be rigid.


Babbling story below, I'm sad about unions.


I installed 2 used 3/4in copper unions just fine.. they were older. (someone else soldered it)

I thought I could install a new half inch one just fine... Maybe I heated it up too mich and cooled it too quickly?
I was shocked by how hard I had to tighten it to stop it from leaking.

I had some new 3/4 unions and got some solder on the mating face.. I took it off and put on another one.

When I attached it, it leaked like a sieve.. I am sure I had it in line because the other side was not locked down yet.. I was going to fasten it based on the union alignment... I jiggled it, I wiggled it, (I couldn't beat it because the heat exchanger seems fragile).

I then tried to see where it was touching by using sharpie and seeing if anything rubbed off. only a tiny bit rubbed off.

I then tried using toothpaste to lap it, but nothing touched.

I found a union with female threads on one side... that seemed better than trying to align a pipe.. The wrench faces/(nut) are larger, so it had trade-offs I got it installed... and... there is a drip every 2 minutes or so, so it's not good.


I did make a mistake with a dielectric union by leaving it in water (for a short time) (thought I was getting flux off) and it rusted and leaked, but put a new one on and it was fine...

 

[Jamesplumbing06]

So your a novice? Using a 2000 degree flame in a nice dry wood house ?

6-8” of pex and 2 - 1/2” sharkbite coupling.

Go do it. Don’t overthink it anymore.

shhhhhhhh. You can him haul around after it’s fixed.

got it fixed?

Now. Sleep well. No more fuss no more instructions needed.

I am a service tech/plumbing service business owner. I use sharkbite. They are not permanent but will out last the copper. I warranty every job and stand behind it.

Somebody is gonna call me non professional. But I work for my customers. If those bosses say get it fixed as fast as possible and make sure it outlasts the current pipe. Then I sharkbite and gone in 5 minutes.

I will not take an open flame inside a seasoned wood frame house. With spider webs catching dryer lint. 1 wrong position of flame And your in the biggest flash fire you ever seen. Then just as quick as it lit. It’s out and all the oxygen is suddenly sucked from area. So your gagging for air as you emerge from smoking crawlspace. Your a professional that nearly burnt down a house. Is that professional? Just to weigh your wooo wooos? Leaving a house fully intact upon completion is professional. And sharkbite never burned down a house.

you still reading? Go fix the leak. Lol

good luck.

 

[AirOp]

It's summer and we're not using the system right now. I've done most of the soldering outside. I've got a fire extinguisher and the flame resistant cloth for the couple of joints I have to do in my house.

I thought sharkbite connecters were expensive until I saw the price of the copper fittings.. I've got the tools to do pex, but oxygen barrier pex (OMG, this Macintosh won't let me write PEX) isn't sold in the small quantities I need.

I really do want to know how to make the copper union work. With the geometry of how everything goes together, I'm pretty sure it makes sense to use a union here.

(The heat exchanger is stainless steel, and I was assured that I don't need a dielectric union by the sales guy, but I might just use one anyway)

I'll be using copper flexible tubing with dielectric connectors for most of the connections anyway..

Also, they are 3/4in

 

[Mitchell-DIY-Guy]

@AirOp I once owned a car wash, and trust me when I say I had more plumbing and fittings than you would believe. Miles of ¼" PE tubing, copper tubing in all sizes up to 2". I used 100,000 gallons of water a month. I had 25KVA of power to the building and pumps up to 3-phase, 25HP.

I never had a problem with unions. However one thing I discovered is that not all unions are alike and you have to have the mating set. Even if the two pieces fit together doesn't mean they are made to work together; the mating surfaces are different.

I always used, for costly parts like a brass union (they are not copper by the way) THREADED varieties as opposed to solder on styles. Yes, you needed male adapters on the ends of your copper tubing, but things were always being fixed and reconfigured and a threaded fitting can be reused.

While I did a lot or most of the work maintaining this car wash beast myself, I often called upon my car wash supplier for his best tech, Patrick. Pat had decades of experience and taught me a lot. On any threaded fittings we always used a good quality teflon tape; LA-CO if you can find it. We always used a thread sealant in addition to the PTFE tape. Pat also always put a slight coating of thread sealant on the mating surfaces of the union. I don't recall every having a union leak.

Buy a good quality union.

 

[CT18]

Yes we would also add some to the union connection to prevent it from galling and help it seat. That is what the old timers would tell me so i went with it. It may just be a poorly cast fitting and needs to be replaced.

 

[AirOp]

Where do you get your fittings /what brand?
I found that home depot's fittings seem worse than Lowes, and the plumbing supply shop actually had the worst.
The ones I got from amazon seemed nice.with female thread on one side and sweat on the other. they're brass. What else do you look for?

There is a chance that the one that was leaking so bad was a missmatched pair, from the same manufacturer / I had goobered one mating surface and could have borrowed that part from another one in set.

I always used, for costly parts like a brass union (they are not copper by the way) THREADED varieties as opposed to solder on styles. Yes, you needed male adapters on the ends of your copper tubing, but things were always being fixed and reconfigured and a threaded fitting can be reused.

While I did a lot or most of the work maintaining this car wash beast myself, I often called upon my car wash supplier for his best tech, Patrick. Pat had decades of experience and taught me a lot. On any threaded fittings we always used a good quality teflon tape; LA-CO if you can find it. We always used a thread sealant in addition to the PTFE tape. Pat also always put a slight coating of thread sealant on the mating surfaces

Buy a good quality union.

 

[Pat the Plumber CIL]

Modern Unions suck , most come from Korea , China , Indonesia etc, etc . Back in the good old days American made stuff sealed and worked muck better . Now it all sucks . If all else fails wrap male mating surface with high quality Teflon tape . Preferably Blue Monster 1/2 inch heavy duty . Wipe tape and threads with dope (Megaloc) and tighten with large cresent wrenches ( 12 inch or larger)

 

[AirOp]

I have a few older unions from the previous assembly... I just had so much trouble reusing fittings because of solder being on the pipes (and I didn't have a good enough torch before)

I also found my file file so I can get enough solder off so I can get the fittings to dry fit before fluxing and soldering...

So putting teflon tape on the mating surface... may be required?

How do I know what "high quality" tape is?

I used to install dishwashers for a big box store, and I'm pretty good at applying the white stuff cleanly and evenly... never had one of those leak.. but this is like a compression fitting... I'm not happy with the thought of it.

I think I might have screwed it up by heating it too much.

 

[AirOp]

Ok, I should change the title to Brass Union leaking. (I should have known the difference, but I figured I was working with copper pipe)

My Uncle's house is all PVC from the pressure tank thru the water filters, then copper to the house... PVC unions I've not had a problem with