pex connection in air line leaking..

vanguard machine · Aug 21, 2020

I added a few extra short runs into my air system last week and as it's 'situationally temporary' i went with pex. I have two joints that are leaking fairly well at 100 psi. of course as it happens the two joints are the most pain in the ass ones to get to and really difficult to work around and 25' up in the rafters where it's about 120 degrees. I can cut them apart if I need to and redo but I'll have to redo a bunch of stuff up to and after, so trying to avoid going that route if i can out of shear frustration and laziness. so...Does anyone know of any tricks to seal up an existing pex connection? safety wire? heavy duty hose clamp behind the pex collar? i used the 'pro' collars with the nub and I made sure that I homed the crimper all the way.
luckily the other 20 or so are good.

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Milland · Aug 21, 2020

You might try something like this self-adhering butyl tape as a sealing overwrap, then back it up by splitting a copper sweat reducer of appropriate size to go over the wrapped fitting and compress it down using hose clamps.

1 in. wide X 1/8 X 50 ft. High-Temp. Butyl Rubber Sealant Tape (1)

Some guessing may be needed to build up the layers of tape to a level that gives the right compression to stop new leaks, but with that figured out it should hold pressure.

This is the same sort of conformal double-sided tape as used to seal some machine enclosures.

vanguard machine · Aug 21, 2020

Milland said:
You might try something like this self-adhering butyl tape as a sealing overwrap, then back it up by splitting a copper sweat reducer of appropriate size to go over the wrapped fitting and compress it down using hose clamps.

1 in. wide X 1/8 X 50 ft. High-Temp. Butyl Rubber Sealant Tape (1)

Some guessing may be needed to build up the layers of tape to a level that gives the right compression to stop new leaks, but with that figured out it should hold pressure.

This is the same sort of conformal double-sided tape as used to seal some machine enclosures.

i actually have some of that.. used it once for an emergency tig torch repair (coolant shooting 10' across the fab table haha)
only problem is wrapping my hands 360 degrees, or close, will be nearly if not entirely impossible on these two. both 90's, outside and inside corners with zero room around them other than whatever stretch i can massage out of the 1/2" pex

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Milland · Aug 21, 2020

When stuff goes wrong, it always does so in the least convenient manner...

Maybe Loctite makes a miracle wicking goop that you can drip over the fitting, and have it set up firm. Hell, it might be worth talking with their applications engineers to see if anything could work.

Would be best to pull a mild vacuum on those lines until the stuff sets up...

Rob F. · Aug 21, 2020

Did you use copper crimp collars to crimp the pex to brass fittings? If so just get some thin metal and to line the crimper with so it will squeeze a little more and recrimp. Aluminum can might be right thickness, SS shim stock would last longer, grinding the edges of the dies so they crimp more would be more permanent...

eKretz · Aug 21, 2020

You could try one of those methods above, and here's another idea:

I've used this method on airlines plenty, works great. They sell these tools, I made this particular one myself. You could set up the wire so it straddles the crimp fitting for a little extra bite. I just use stainless MIG wire of suitable size. Stainless wire works better when it's annealed first, easy to do by running a little current through it until it's red hot, then letting it cool.

Joe Rogers · Aug 22, 2020

Additional sealing bandaids all sound like last resort after a recrimp try fails. I’d recrimp but index the tool at 90 degrees rotation to the original tool position.
Joe

Lewie · Aug 22, 2020

Sounds that it was so hard to get at the right way that it "probably" is the reason it isn't quite done right. :-)
...lewie...

vanguard machine · Aug 22, 2020

Lewie said:
Sounds that it was so hard to get at the right way that it "probably" is the reason it isn't quite done right. :-)
...lewie...

re-read my initial post.
it wasn't done the 'right way' because it's temporary. i have over 300' of 3/4 sch 40 black pipe and about 25' of pex.
doesn't mean i did shit half assed. still planned everything, took my time, etc.
cost vs benefit

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vanguard machine · Aug 22, 2020

eKretz said:
You could try one of those methods above, and here's another idea:

View attachment 297424

I've used this method on airlines plenty, works great. They sell these tools, I made this particular one myself. You could set up the wire so it straddles the crimp fitting for a little extra bite. I just use stainless MIG wire of suitable size. Stainless wire works better when it's annealed first, easy to do by running a little current through it until it's red hot, then letting it cool.

trying this now with regular safety wire pliers and 1/16 316 tig wire that i annealed with the torch. fingers crossed

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Bill D · Aug 22, 2020

All the bad pex joints I have made, out of under 50 total, the clamp was cockeyed. 5-15 degrees off square and it will not seal. If I had to redo it up there I might replace the coupling with a ball valve, just in case.

When I redid the supply lines under hte house I used a lot of valves so I could do it over several days and still have water in the house at most fixtures.
Bill
Only 120 F I thought it would be hotter there. It was almost that hot outside this week.
Bill D.

vanguard machine · Aug 22, 2020

so i tried the annealed ss wire and of course it snapped at the pliers end before getting much pressure on the fitting. still it bit a little, which has to help some. probably wishful thinking.
i then mixed up some prosumer 5 minute epoxy and completely covered the joint then came back and did it again. also prob just more wishful thinking.
gonna eat some lunch then pressurize to maybe 50 psi at first and see how it looks.
if all else fails i'll go to home depot for more fittings, drag the extension ladder back in and just redo that entire section.

will report back in a few hours

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vanguard machine · Aug 22, 2020

Bill D said:
All the bad pex joints I have made, out of under 50 total, the clamp was cockeyed. 5-15 degrees off square and it will not seal. If I had to redo it up there I might replace the coupling with a ball valve, just in case.

When I redid the supply lines under hte house I used a lot of valves so I could do it over several days and still have water in the house at most fixtures.
Bill
Only 120 F/ I thought it would be hotter there. It was lamost that hot outside this week.
Bil lD.

only 120 lolol
i'm miserable with anything over 75

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dkmc · Aug 22, 2020

I used JB weld on a cracked alu. dump valve once. I thought it would be a joke, but it never has leaked since, 120 PSI.

dian · Aug 22, 2020

wrap it heavily with a strong thread/string and wick instant glue into it.

vanguard machine · Aug 22, 2020

dian said:
wrap it heavily with a strong thread/string and wick instant glue into it.

interesting.
even for non-threaded connections?

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ferrretcatcher · Aug 22, 2020

Do they make a sharkbite that will fit over Pex? maybe that would work, it seals 80psi water.

dian · Aug 22, 2020

vanguard machine said:
interesting.
even for non-threaded connections?

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not sure what the geometry of those joint is, but this tends to fix almost anything. e.g. obsolete, leaking automotive injectors. no leak after 10 years.

vanguard machine · Aug 23, 2020

i applied a generous amount of super glue to every new joint and read that it takes 24 hours to cure so about to go pressure up and run around with a bottle of soapy water... hopefully not chasing my tail lol.

here we go... fingers crossed [emoji1696]

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aliva · Aug 23, 2020

Cut the offending joint out and reconnect with Sharkbite fittings. I've used them for years never had a leak. There are also removable if needed. They work on PEX, Copper, PVC, and CPVC. They also have a special fitting to connect PVC to CPVC

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