Any hope in re-sweating copper tubing?


In doing some recent plumbing work, I had to sweat a particularly difficult and oddly shaped joint in the bathroom wall. I was surprised when I turned on the water valve and it actually held! (I've never been good at soldering copper tubing,)
Anyway, a week later, it developed a pinprick leak. In the past, I've tried to re-sweat joints to no avail. But maybe I'm overlooking a special technique or product.
Any help would be appreciated. I used tin/antimony solder. For now it looks like I will have to disassemble the whole thing and that will be a real mess because I will have to tear part of the wall apart.
Thanks.
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Try cleaning and redoing as you shouldn,t go over solder sounds like you didn,t have it really clean and enough flux
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Have to agree it's unlikely to get a better joint after the water has been on and it developed a leak.

Or, even more likely if it was new work, I'd suspect not evenly or enough heat to get full solder flow into the joint. What are you using for the heat source and how do you apply heat to the joint? Need enough heat _above_ the joint itself (back into the fitting direction) to melt the solder all-way-'round the joint w/o the flame itself being the heating source. Then, apply the solder so it wicks in--if it's hot enough, it will almost magically just seem to suck it up into the joint.
If it's an enclosed location, a heat shield behind to avoid direct flame on flammable is a good idea and can alleviate some of the concern. Key is to have enough heat to heat the joint quickly and then get it hot enough before oxidize the flux and it loses its effectiveness and to get even heat. If access is limited, may need a longer torch or other aid to get to location. Sometimes it is more effective to make this difficult joint in the open, then do the final connection at some other location that is more accessible.
On rework like this, be sure to get all water out to make it simpler. If there's a problem, there's always the bread sopper trick if all else fails in getting the last few drops from continuing to get in the way...
HTH.
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I had a pinhole leak clog and stop once; you might get as lucky. Otherwise, do it all again!
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Make sure there is NO water in the pipe. Sometimes it will sit right at the joint after you take the connector off. The water will act like a heat sink and make it a lot harder to sweat together. Find the lowest point in the home to drain the water back.
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To help remove the water either use a shop vac with a jury rigged collection of tubes taped together to get the size needed to fit over the copper fittings, sometimes it can take 15 to 20 minutes to remove trickles of water from a line, open a tap on a far away upper floor to aid in the airflow. Sometimes a compressor can be used to blast the water from a higher level down to where you are working.
The old lead/tin solder was much more forgiving in its use with a wide temperature range where it was "mushy" and could be worked into a joint and form a fillet. The lead free versions are difficult to get a tight joint. Overheating can cause it all to flow right out a joint leaving pinholes. Sometimes it pays to just add a little lead/tin solder over difficult lead free joint just to build a fillet to plug those pesky pinholes.
wrote:

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bdeditch wrote:

Or, easier still, go to the local Ace hardware store & get some of those pellets that you put in the pipe to plug it. The pellet, jelly bean or whatever you want to call it gets pushed into the pipe at least 6" thereby plugging it, then when the joint is all done, heat the area where the pellet is and it will dissolve.
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46erjoe wrote:

If you can see where the leak emerges, before you start messing with a torch, try peening the solder down with a hammer and small punch, use something like a nail set maybe.
I've "got lucky" that way a couple of times. If you get it to stop leaking it will probably stay that way forever.
Jeff
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USE MAPP gas, its a little hotter and helps in more challenging locations.
Completely redo the joint, replace any cheap fittings, it will be easier that way!
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Using new fittings is naturally best. But I have been lucky to have a glass bead blaster to use for cleaning fittings. The routine that works best is to heat the fitting, wipe out as much old solder as possible with something (I used a paper towel, quickly) and while still hot, brush it with flux, wipe again and cool, then clean it in the blaster. Use the fitting before the copper oxidizes again and you get perfect joints, even with the new lead free solder. I built my glass beader for less than $100 and that doesn't qualify as an expensive tool IMO.
Joe
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Well, I tried re-soldering. Leak returned. Took it all apart and created a new routing system. Did as many joints away from the site as possible then put it together, this time ending up with five sweats. So far it's holding.
I think I need to find a website with helpful info on sweating copper. I learned by trial and error and I probably need to UNleard some things. I also learned that different fluxes go with different kinds of solder. I thought they were all the same! Hey lead is lead, right? Wrong.
Thanks everybody. Keep your finders crossed.
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46erjoe wrote:

Wrong. Lead is lead, but what you solder together and it's purpose is different. Course you aren't suppose to be using lead solder for water pipes anyway.
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Well, there's no lead in plumbing solder any more. It's now almost all tin, with a little bit of antimony or something else (but definitely not lead).
Having said that, I've always had good results using decades-old acid paste flux with the new lead-free solder as long as the surfaces being soldered are clean.
It would be useful to know *why* you got that pinhole leak (yeah, I know, probably too late now). If you just didn't get it hot enough or apply enough solder to get sucked into the joint, but it's otherwise clean and adequately fluxed, reheating might work. But if it's dirty inside the joint, no amount of reheating is likely to help.
    Dave
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The problem I had one time, I was waiting too long to apply the solder. The fitting would all dry out, and by the time I applied the solder, it was dried and oxidized. Got to put the solder to the joint while you are heating. At some point, it sucks the solder in, and then you stop heating immediately at that moment.
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replying to 46erjoe, Sid in Sacramento wrote:

I have seen even the Pros have difficulty sweating some copper joints, you might look into using ' Sharkbites ' for the joints, they sell them at your local home depot or lowes, and are rated for behind the wall placement !
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On Wed, 24 Jun 2015 00:44:04 +0000, Sid in Sacramento

boiling water, and use a good high heat torch - a turbo-torch on MAP or an air/acetylene plumber's torch will do the job. With the old standard Bernz0Matic propane torch you can pretty well forget about it. With a turbo torch on Propane you have a fighting chance.
If there is water in the pipe, you might manage in a week as long as the water is turned off and one eng is open.
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