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goop for unions?

Joe_119
Joe_119 Member Posts: 2
I bought a pair of 2" stainless unions from an internet business last year, and a pair of 1-1/4" brass unions from PexSupply. Used the brass unions to connect my munchkin to the primary loop of my heating system, and the stainless unions to connect the loop to my big heat exchanger for my wood fired outdoor unit. I used teflon paste pipe dope on all threaded connections.
When I started the heating season this year, the unit ran good for about a month. One morning, no heat. Upon inspection, it had a low water pressure fault. Got to looking and both unions had developed leaks. One brass unit leaked at the sealing face, and one stainless unit was leaking at the threaded connection and the face, also.
I undid the brass union (plenty tight) and ended up putting pipe dope on the sealing faces, which stopped that leak, but a new one started at it's threaded end. I am letting that one go for a bit until I can get some rector seal and a warm day to where the house doesn't cool down so much while I disassemble the plumbing to fix these two leaks.
As far as the stainless fittings- they are of foreign manufacture. I can get a real good grip on the offending union with big wrenches, but it just don't want to seal.
I think sealant on the face is going to have to be the way to fix it, although I don't believe it is right. I think poor quality is the problem.

Comments

  • Royboy
    Royboy Member Posts: 220
    array of solar collectors that won't hold pressure

    just finished getting eight 4x10 solar collectors flush mounted on a 45 degree metal roof in northern WI winter conditions. slow process but it all went well. until I pressure tested the array and found every union is leaking air through the mating surfaces!

    1" sweat Nibco unions, factory installed on the collectors. a call to the factory resulted in them telling me that Nibco recommends either "silicone spray" or beeswax on the mating surfaces prior to asembly. one of the people at the manufacturer, who's worked in the HVAC trade, told me he always smears pipe dope on union faces. I've always installed them as is, and occasionally put some pipe dope on one if I had problems getting a seal.

    so question 1 is: do you goop union surfaces prior to assembly or not?

    question #2 is what product might I be able to get to flow into these unions to give me some help in sealing. its possible but a definite last resort to imagine loosening/moving the collectors to open up the unions. as they are, I can spread the two halves maybe a 32nd or a 16th. getting pipe dope in there seems unlikely unless it was something pretty liquid. I tried a silicone lubricating spray as per Nibco's recommendation on a couple of them and I think it flowed in fine but it didn't stop the leakage. a lithium gease is one suggestion that's been offered. anybody know how to thin down thick-bodied pipe dopes?

    ideas???

    thanks - Roy

  • Couderay
    Couderay Member Posts: 314
    Unions

    The only thing I ever use on unions is never seize and the copper style is just the ticket for them copper unions. Make sure surfaces are clean and a little seize on the threads and face and it should do the trick.Also a whack with a hammer can and does help on them stubborn unions while putting them together. Where are ya in northern Wisconsin if I may ask.
  • jeff_25
    jeff_25 Member Posts: 110


    i put pipe dope or antisezzis on the threads and on the shoulder under the nut so it not a dry metal to metal it always helps me. you can get to go little tighter that way.. were in wisconsin are you i'm in west allis jeff
  • Royboy
    Royboy Member Posts: 220
    second question first

    probably should have listed my second question first as it is my main concern - what sort of stuff will be liquid enough to get into the very thin gap on these unions and still have enough body to aid in sealing?

    so far, spray-type lithium grease is the only candidate I've come up with.

    locationwise, I'm on Chequamegon Bay of Lake Superior, in Washburn. great place to live!

  • hot_rod
    hot_rod Member Posts: 14,552
    crummy unions

    those copper to copper types. Mis-alignment can be an issue with them. Often times the piping coming out of solar panels is crooked.

    Next time get the unions with the O-ring seals. That type works great even hand tight.

    This time, if you can get them dried off I would try that Permatex Aviation Form-a-Gasket sealant liquid # 3H. The type with the brush on applicator. Liquid enough to flow in but thick enough to do some good. Works fine on glycoled systems, up to 400F.

    hot rod

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 14,552
    Or...

    apply some solder flux on that face along with the threaded union and heat away with some solder in hand. I've done it more than once ;)

    In all honesty my last ADP 8 panel install, I used sweat couplings due to the bad match up. I have a can of "Hot Dam" to protect the panels from getting too hot as I soldered close to the panel. I used my B tank with a small Turbo Torch tip for a quick concentrated heat.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Kevin Pulver
    Kevin Pulver Member Posts: 67
    Automotive RTV silicone

    It won't flow, but if you have to open them up, it will do the trick for sure. Handles heat and pressure cycles and antifreeze every day in mobile applications around the world.Kevin
  • realolman
    realolman Member Posts: 513
    I often

    put pipe dope on the threads and shoulder for lubrication to let you crank them easier, and get them back open again, but I think if you have to put something on the sealing surfaces , there's something wrong with the union.... Nibco you say... remind me not to buy any of them.
  • Royboy
    Royboy Member Posts: 220
    silicone

    in one form or another has been my fall-back for tough unions and its always worked well. keep a little hardware store tube of the "pure" stuff in my bucket for all sorts of sealing situations.

    problem here is the difficulty of opening the gap in the union. will probably give the permatex hot rod suggested a try.
  • Royboy
    Royboy Member Posts: 220
    solder

    would not be my first choice, both cuz of the uncertainty of getting faces clean and since, in theory, at least, it would be nice to be able to dissemble the array should it ever be needed (hope I'm not the one to do it!). that's why I like ground mounts, but this needed to be on the roof to see over trees.

    the permatex sounds like a possible fix. wondering what the implications are going to be on the two unions where I tried Nibco's suggestion of silicone lubricant. might be able to get in and "floss" them with a thin rag.

    it'll be after christmas in any case so the suggestion box remains open for a while ... :-)

    crooked pipe stubs are really a drag, on collectors, on boilers, wherever. makes you wonder what the manufacturers are thinking (or not!). this was my first install with these particular collectors - AET units from Solar Skies out of the Twin Cities - and the unions are the only issue I had. otherwise fit & finish, detailing, alignment, & crating all excellent.

    thanks!
  • Royboy
    Royboy Member Posts: 220
    who makes

    O-ringed unions?
  • hot_rod
    hot_rod Member Posts: 14,552
    I buy the O-ring unions from

    Watts Radiant # 81000443 for 1" sweat.

    Heliodyne out of Calicfornia sends their panels with these unions also.

    One of Watts Industries companies in the south makes them, as far as i know.

    I reinstalled some old Lennox panels this summer for a friend. He bought some high temperature silicone rubber hose from an auto parts store 1-1/8" id. Two clamps per side with about 2" slid onto the 1" copper stub outs. Same hose Lennox sold with the panels 20 years ago. Expensive but it sure handles that mis alignment well.

    If I were a panel manufacturer I send them with that corrugated stainless steel flex sticking out the side. Very easy to use and union together.

    Whatever you end up doing, be assured glycol will find a path to leak through most any threaded assembly :)

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Scott Kneeland
    Scott Kneeland Member Posts: 158
    dope on unions

    I was taught that unions and flare joints are mechanical seals and DONOT put dope on mating surfaces. I have had problems with Nibco 1/2" copper unions. As of yet I have not been able to find another brand in my area.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • hot_rod
    hot_rod Member Posts: 14,552
    look at this copper union

    that I removed from a job a while back. Looks like someone added a homeade gasket to help it seal. It worked, as yet another option.

    I think the quality of workmanship has slipped with all imported fittings. Without a nice machined surface and perfect match up, there is not a great seal area in copper unions.

    It is also tricky to solder next to a union surface without getting any solder run-off into that seal area. You almost need to grease the surfaces to keep flux and solder out.

    The nicely machined union on the left is the Watts version.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Ron Gillen
    Ron Gillen Member Posts: 124
    A little heat and dope

    For that tight gap a little heat should get most dopes to flow like water just warm the union with your torch. I put a very small amount of dope on the face and male threads of all unions, always worked well. Jet Lube #60 comes to mind,on start up, if you use too much it drips pretty well.
  • realolman
    realolman Member Posts: 513
    Amen

    hot rod - "I think the quality of workmanship has slipped with all imported fittings."

    amen to that.
  • PeterGriffin
    PeterGriffin Member Posts: 79
    NIBCO



    Is an American brand is it not?

    We did 26 reheat coils on a high school job and my only leaks were on NIBCO 3/4 sweat unions, not all of them, probably half. They all sealed up when I took a bigger wrench to them, though.
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,081
    Another trick...

    ... that's worked for me is to put two turns of teflon tape on the union threads, but done so it hangs over the mating surface. This helps the union tighten down better and puts a skinny gasket between faces. This trick has not failed me when putting collectors together.

    Yours, Larry
  • Douglas Hicks
    Douglas Hicks Member Posts: 69


    And sometimes if you tighten the union to much, it leaks. try backing off the pressure. Try to adjust the tightnes factor while the union is under pressure. I seem to have better luck w/a bit of good pipe dope on the face of the union.
  • hot_rod
    hot_rod Member Posts: 14,552
    Best one yet, Larry

    Have you used any of that thick Mill-Rose "Three Wrap" teflon tape? It really seals well with two or three wraps, much thicker stuff.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,081
    Yes!

    Hot Rod, you're right on. I like their gas line tape particularly. I'd never noticed the one and a half inch maximum on pipe size though. My eyes must be getting older ;~)

    Yours, Larry

    ps. Looking forward to Wetstock!
  • Rob Blair
    Rob Blair Member Posts: 227


    I tried the milrose 3 wrap after two recommendations within two days. Out of 10 fittings, 3 were leakers/seepers. Still sold on the wrap and dope combination. One leaker can really throw a wrench into the job.

    Rob
  • I've never...

    put anything on the mating surfaces of unions but ALWAYS put a dab or two of Rectorseal (my personal favorite) on the threads and shoulder. I avoid the mating services to prevent getting any contaminants in my system.
  • Royboy
    Royboy Member Posts: 220


  • Royboy
    Royboy Member Posts: 220
    I'm smiling tonight

    after trying hot rod's suggestion of Permatex 3 on 4 (of 16 unions). didn't want to goop them all up if it wasn't going to work, but those four didn't leak when I was done.

    here's what I did. backed the nut off the unions. opened up the unions the best I could - in the case of the between collector unions (all but 2 of the 16) I drove a wooden wedge between collectors and opened them maybe 1/32 at best. it being 20 degrees on the roof, I heated the unions with a torch, let them cool til I could touch them, then pulled the permatex can out of my pocket (where I was trying to keep it warm) and did my best to get permatex into the gap with the brush from the can without getting brush fibers caught in there. I was pleased to see the permatex thin out on warm metal and drip off the low part of the union. tightened the nut down quite snug. waited 4 hours - as per specs for permatex 3. fired up the compressor and voila! - no air bubbles when hit with the leak testing fluid at 100 psi.

    thanks all & thanks HR! - even though your final message said you thought Larry's teflon tape idea was your favorite. I was a little unsure of being able to tuck the tape into the mating surfaces without being able to open the unions wider.

    expect to be sleeping much better tonight and will go back and do the rest tomorrow now that the 4 test unions worked.

    Roy
  • Canuck_3
    Canuck_3 Member Posts: 38
    I think its all been answered but

    doesn't anyone use Heat-Pruf grease anymore. I find it takes the 'sin' out of most connections. You can use it on any 'poly', latex or resin material, unlike dope. It's compatible with potable water systems.... and it's not bad, spread on a bagel either,(just kidding).

    http://www.statesupply.com/displayCategory.do?cuid=MS2172A
  • hvac used nylog

    it's a snot-like goo that comes in a small-tipped squeeze bottle, and it's perfect for union faces
  • Al Corelli_2
    Al Corelli_2 Member Posts: 395
    Teflon

    Whenever faced with a leaking union, I do as Larry does and I've been very successful.

    I was brought up (Dad rapped my hands with a 10" wrench)to NEVER put dope on unions or flare nuts. I was also reprimanded (same 10" wrench flying across the boiler room towards me)many times whilst trying to put some sort of sealant on coil gaskets.

    To this day (winces from past pain), I put coils in dry and they never leak, and 99.99 percent of unions and flares don't either.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
    Al Corelli, NY



    914-804-2234
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