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Author Topic: Leaky sweat joint  (Read 96 times)

Roger2561

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Leaky sweat joint
« on: May 24, 2018, 02:41:53 PM »

Does anyone know if there is a compound available that will stop a leaky sweat joint on a copper pipe?  It's on the domestic water line coming into the house.  My sweat skills have a lot to be desired so I'm a bit reluctant to try but I will if there is no compound that I can simply apply to stop the leak. 
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coolidge

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Re: Leaky sweat joint
« Reply #1 on: May 24, 2018, 06:25:01 PM »

Sometimes if you can drain the water out of it, heat it up again with a torch it will seal  itself, let cool before refilling.
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RSI

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Re: Leaky sweat joint
« Reply #2 on: May 24, 2018, 07:49:23 PM »

I have seen doing that turn the water in the joint turn to steam and blast the liquid solder out.

If you so try soldering, I would plan on having to take it apart and re-sweat.

I am not sure they still make the stuff but they used to make some putty stuff that was for that purpose. I tried some many years ago and it worth of worked.
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greasemonkoid

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Re: Leaky sweat joint
« Reply #3 on: May 24, 2018, 11:25:20 PM »

There are alloys that melt in boiling water, not sure if they adhere to copper though. I've got a chunk, have yet to find a good use for it after 20 years.


Soldering seems like a sort of black magic to me. Filling a gap without it running out remains a mystery. I just finished hooking up my heat exchangers and out of a dozen joints 4 leaked. It only happens when it's copper to brass. Copper to copper seems foolproof.
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Roger2561

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Re: Leaky sweat joint
« Reply #4 on: May 25, 2018, 02:58:05 AM »

There are alloys that melt in boiling water, not sure if they adhere to copper though. I've got a chunk, have yet to find a good use for it after 20 years.


Soldering seems like a sort of black magic to me. Filling a gap without it running out remains a mystery. I just finished hooking up my heat exchangers and out of a dozen joints 4 leaked. It only happens when it's copper to brass. Copper to copper seems foolproof.

greasemonkoid - The leak is exactly where you describe, at a copper to brass fitting.  Looks like I'll be draining the water and drying it the best I can to make an attempt to resolder it myself.  Thanks.  Roger
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wreckit87

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Re: Leaky sweat joint
« Reply #5 on: May 25, 2018, 07:19:21 AM »

Blue Monster makes a compression seal tape I saw on the shelf at the supply house a couple months ago. Never tried it myself, but the guy at the counter said it works well and the label was pretty encouraging as well. Those copper to brass joints can be troublesome sometimes, the best I've found is to clean and flux the heck out of the "face" of the brass cup (perpendicular to the pipe) as it's quite a bit thicker than the cup on a copper fitting and tough to feed solder into otherwise. I've had my fair share of leaks over the years and it's kind of a crapshoot on getting those to seal without taking the joint apart. Is this in a position that you are able to disassemble the joint without cutting?
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Roger2561

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Re: Leaky sweat joint
« Reply #6 on: May 25, 2018, 08:20:02 AM »

Blue Monster makes a compression seal tape I saw on the shelf at the supply house a couple months ago. Never tried it myself, but the guy at the counter said it works well and the label was pretty encouraging as well. Those copper to brass joints can be troublesome sometimes, the best I've found is to clean and flux the heck out of the "face" of the brass cup (perpendicular to the pipe) as it's quite a bit thicker than the cup on a copper fitting and tough to feed solder into otherwise. I've had my fair share of leaks over the years and it's kind of a crapshoot on getting those to seal without taking the joint apart. Is this in a position that you are able to disassemble the joint without cutting?

wreckit - I'll have to look up the Blue Monster stuff, I've never heard of it.  No, I'll have to cut it out, it'll be easier to fix on my workbench as opposed to me being tied into a pretzel trying to get to it.  I'm thinking that I can install a copper coupler once the leak has been fixed.  None of the copper to copper joints leak, only the copper to brass.  Thanks for the tip.  Roger
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