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.
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
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.
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.
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.
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.
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.
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?
Thanks everybody. Keep your finders crossed.
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
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.
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.
Christopher A. Young
You can\'t shout down a troll.
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 !
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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