Having trouble soldering copper pipe

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I'm redoing my shower, all 1/2" copper pipes. I've done two couplers, 1 elbow, and 3 threaded connectors... and they all went fine. Just one other elbow had a small leak. I tried at least 10 times last night and continue to have leaks. Maybe I just need to try again tonight with a fresh mind, but...
One problem I've got now is that the two ends going in to the elbow have solder on them. I've sanded them until smooth (they are still solder color, but smooth, is that okay?) and used a new elbow, and did that a couple times last night, but still no go. Is it okay to sand off the old solder and keep trying this way, or do I really need to start with all new pipe? It is easy to keep using new elbows, I've got plenty to spare... but I can't really cut back the pipe, not without adding yet another fitting (another coupler) which just seems like even more work, and eventually I'll have it cut back to the slab and not be able to continue.
The elbow fits well, nice and tight, just like all the others I did, so I have no idea why this one connection is giving me so much trouble. I did only do one other elbow though, so maybe I just got lucky on that elbow. Is there anything special you need to do when doing elbows? I've tried doing one end at a time, and also tried heating in the middle of the elbow and running the solder around both ends, one right after the other (while still hot, so they both cool/ harden at the same time).
I've read a lot about soldering... but, how long do you need to wait before testing? The pipe seems to cool pretty fast, so I've been testing within 2 to 5 minutes, is that not long enough? I kind of wish I could find an elbow with about 6" of pipe on each end, so I wouldn't have to worry about messing up one end while working on the other.
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snipped-for-privacy@surfbest.net wrote:

At the risk of telling things you probably already know and are doing.......
Are you SURE there's no water left in the pipes which is somehow keeping the pipe from getting up to soldering temperature?
Are you cleaning the INSIDE of the part of the elbows which fit over the pipe ends, using a wire brush or abrasive cloth until they are bright and shiny copper?
Are you using a decent paste flux wiped onto the pipe ends and the inside the elbows?
Heating in the middle is not necessarily the best way to do it, you should probably move the flame from one side of the elbow to the other while heating if you're going to solder both ends "at once"
Other than that, I can't think of why you're having problems with one elbow unless someone's put a curse on your plumbing.
HTH,
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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That's okay, I should have explained what I was already doing better anyway.

Yes, at least on most of my attempts I've been removing the elbow completely (and replacing it with a new one) so I can see down the supply end of the pipe and no water is anywhere near the top. A couple times (I mentioned I made a LOT of attempts), when I tried to just fix the minor leak by adding more solder, there may have been some water those times... but I've tried both.

Yes, with a wire brush, that 4-in-1 tool made for the job. I don't spend a hole lot of time on the inside of the elbows though, because they are brand-new and already really shiny. I just insert the wire brush and maybe 6 or 8 twists... I then use toilet paper or paper towel (I've tried both because I'm not positive, but I don't think either have any "oils" or perfumes in them, which I know would be a bad thing) to remove any oil and/or dust.

Yes, "paste" flux. I do notice that it runs down the pipe most of the time, when I start to heat the elbow. Mostly on the end of the elbow pointing downwards, which I imagine isn't ideal, but I'm not sure how to avoid this. I was using too much flux at first, but now I just put a thin coat on.

I think I'll try doing one end at a time again. It wasn't working very well, I think, because I was applying the heat around the middle of the elbow. I was worried that applying the heat to close to the end of the elbow, may heat the pipe faster than the fitting, or not heat the fitting far enough inside so I may only get solder around the edge.

Thanks Jeff. Could be.
One other thing that is going to keep me up at night... is there any way to really know if you made a good solder? If it doesn't leak after a couple days, could it still be a "bad" connection and start to leak after a couple years? I know any connection could leak after a couple years for various reasons, so maybe the question doesn't really have the kind of answer I'm looking for.... what I really want to know, is how can anyone be sure that they did a good job. Unfortunately, based on past experiences, hiring a professional doesn't give me any more peice of mind, again, unless I had some way to check their work, but then I could just use that same method to check my work (and only call a pro if I couldn't get it right). I guess the only plus with hiring someone else, is that I have someone to sue, but I probably wouldn't bother sueing anyway, so guess that doesn't matter for me.
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snipped-for-privacy@surfbest.net wrote:

I'm leaning toward your not getting the elbow and pipe hot enough before you apply the solder. You should be anble to see the molten solder suck into the joint through capillary attraction and flow around the circumference of the end of the fitting if things are going right.
Is the elbow located in a restricted position where you can't get the torch flame very far "around it? If so, sticking a piece of sheet metal an inch or so behind the joint can help "reflect" some of the torch's heat to that side of the fitting.
Keep trying, it's not rocket surgery, and you can only succeed as far as you dare to fail.

Hydraulic (water) pressure testing of plumbing systems is done, but usually only on new construction. I've never heard of a plumber doing a "repair" job on something in a home doing that, but if you want to learn a little more about it look here:
http://tinyurl.com/yopt2w
The only time I ever experienced a soldered copper fitting "blow right off" was nearly 50 years ago a couple of months after I'd moved into a basement apartment in a brand new building. An elbow blew off in the kitchen of the apartment above mine in the middle of the night. My neighbor noticed water running out from under my entry door in the morning and woke me. What a MESS. Being a bachelor, my kitchen cabinets held more than just food, and I lost a few things I wish I still had, among them a 1940's Contax 35mm camera with "Geheime Staatspolizei" (Gestapo) engraved on its back, brought back from WWII by a returning GI. My tenant's insurance paid me a decent amount for it, with the condition that they got to keep it.
Jeff
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Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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Could very well be, I'm not sure how to tell what the right amount of heat is. I read that if it gets too hot, it will burn the flux, which I guess causes problems. I know it is hot enough to melt the solder, because on most attempts I've been removing the flame before applying the solder, just to be 100% sure I'm not melting the solder with the torch.
When I've removed the elbow, most of the time I'm seeing a nice coating of solder where the elbow was (inside), so it must be flowing to the inside like it should. However, I usually do need to run the solder around the pipe, not just touch it in one place and have it run around the pipe "magicly" like I've heard about. I've read different methods, and some say to just apply the solder in one place and it should run around all sides, and other people say to run the solder around in a circle. Which is best/better/correct? I can't really get to the far side very easy, so I guess just holding it in one place would be nice, if I can get that to work.
Should the solder just stay inside and all the way around the pipe? What I'm usually seeing is that some stays at the top, but more flows towards the "bottom" (whichever way gravity pulls it). So I usually do have solder all the way around, but a bit more in the direction that gravity was pulling it.
After reading the post by Heathcliff, I am starting to wonder if I'm getting solder in the right place, but maybe water or air is flowing through prematurely and creating narrow paths for the water to flow through when I turn the water back on. I'm 99.9% sure there is no water, but I hadn't thought about air.
The first thing I'll do when I try again tonight is to open the shower faucet, that way air can escape that way, and also water if it boils up that far (but again, I'm pretty positive there is no water).
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Could very well be, I'm not sure how to tell what the right amount of heat is. I read that if it gets too hot, it will burn the flux, which I guess causes problems. I know it is hot enough to melt the solder, because on most attempts I've been removing the flame before applying the solder, just to be 100% sure I'm not melting the solder with the torch.
CY: Heat the other side of the pipe. Keep the solder in contact with the crack between the fitting and the pipe. When it just barely flows, that's enough heat. If at all possible, make all fittings horizontal.
When I've removed the elbow, most of the time I'm seeing a nice coating of solder where the elbow was (inside), so it must be flowing to the inside like it should. However, I usually do need to run the solder around the pipe, not just touch it in one place and have it run around the pipe "magicly" like I've heard about.
CY: H eat the bottom of the pipe, and touch the solder to the top. Run the solder left and right, so it flows down both sides. For horizontal fittings, when the solder drips otu the bottom, that's enough.
I've read different methods, and some say to just apply the solder in one place and it should run around all sides, and other people say to run the solder around in a circle. Which is best/better/correct? I can't really get to the far side very easy, so I guess just holding it in one place would be nice, if I can get that to work.
CY: Ideally, it flows all around, but I usually apply solder all around, manually.
Should the solder just stay inside and all the way around the pipe?
CY: Yes, it should stay inside and all around. Does, if the fitting is bright clean, and very tight when you push it together. Sand the outside of the pipe, and wire brush inside the fitting.
What I'm usually seeing is that some stays at the top, but more flows towards the "bottom" (whichever way gravity pulls it). So I usually do have solder all the way around, but a bit more in the direction that gravity was pulling it.
CY: If the fitting is horizontal, apply enough solder so that it drips out the bottom.
After reading the post by Heathcliff, I am starting to wonder if I'm getting solder in the right place, but maybe water or air is flowing through prematurely and creating narrow paths for the water to flow through when I turn the water back on. I'm 99.9% sure there is no water, but I hadn't thought about air.
CY: Well, never know.
The first thing I'll do when I try again tonight is to open the shower faucet, that way air can escape that way, and also water if it boils up that far (but again, I'm pretty positive there is no water).
CY: Good to leave a faucet on, after (downstream from) the fitting. That way any pressure that builds up from the heating has an escape.
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As to "good" joints (lot of experience soldering all sorts of stuff here), I can tell a good joint generally just by inspection. This applies to electronics as well as pipe, etc.
You should see a meniscus of solder evenly flowing between the two items. There should be no "bare" spots, or clear inclusions of crud, excess solder, blogs, etc. Look at the joint with a magnifying glass, if possible. If the joint is in a hard to get at location, then observing the back side can often be done with a good flashlight and inspection mirror.
I've found, when teaching people to solder, that they should PRACTICE on some scrap stuff first to get good technique. In dealing with plumbing, most of the problems are due to much too much heat. You just want enough heat so that the solder just flows easily. Dirt is your enemy. Emery paper, wire brushes, and steel wool are your best friends. Flux simply serves to remove final bit of surface oxidation.
I really like rosin core solder, even for plumbing. The new lead free solders work at a slightly higher temperature, and in my experience are harder to get good joints with, especially if you have grown up on lead bearing solders. I am reluctant to use acid core solder, as the residue is hydroscopic, and corrosive, and will come back to haunt you later.
Also, I find it useful to "pre fabricate" as much stuff on the bench, then finish up with maybe two joints to be soldered in the final work.
Also, in working with OLD plumbing, you have to deal with corrosion. Sometimes I've used compression fittings instead of soldering. Of course, use TWO wrenches to tighten them up so as not to twist the pipe.
Hope this helps..
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O-boy, I may redo a couple of my other fittings after doing this. At least the first two couplings I did, which are now closed off already, looked really good. They didn't even leak the first time, but I redid them anyway because I wasn't happy with the way they looked, and I didn't want to open the wall again after I closed that part.

I think I started with an acid core solder, and those first two couplings were that kind (they are already closed off, so I sure hope I don't have problems with them). I got the one marked "premium" the 2nd time (I used a whole pound of solder doing the first two couplings, until I learned how it should really be done, then only needed the last few inches to do the job right). This "premium" says something like "solid wire", don't have it in front of me, but I do recall it didn't say "acid core" like the 1st one I had.

Yes, I started doing this after a while, and it is a great idea. Another plus is that I don't have as many burn marks on the sheetrock and studs =] Just kiddin, I'm being safe.

I was thinking about trying something else (I read about "Sharkbites" as well), but I think if I get to that point, I'll just call a professional instead. I'm putting $500 worth of tile over this job, and don't want to tear it out.
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Since your problem seems to be on one joint, it is possible that the end or that pipe is slightly out-of-round, causing the problem. Try replacing that one piece and see if the problem goes away.
Bob
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I'd cut the pipe back and add a coupling. You say you keep sanding the used pipe ends and get it to clean solder, but the problem may be beneath the solder. For example, if the pipe was not initially properly cleaned and fluxed, the problem may be under the thin solder coating that is left, where there is some contamination causing problems again each time it reflows.
The other choice is to sand off all the solder on the end of the pipe down to bright copper. Make sure you clean the inside of the new fitting too and then apply flux. Using the wire brushes that are made specifically for that is the best way. They also make them for use on the outside of the pipe and work much better than sandpaper. They look like a doughnut and you just rotate it around the end of the pipe.
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On Oct 23, 9:57 am, snipped-for-privacy@optonline.net wrote:

I'll have to do this if I can't get it after several more tries. At least then I can do the elbow part on my workbench, where I can easily get to all sides and rotate the part as well. Then do the coupling inside the wall, where it is harder to get around to the back side... but I've already done two couplings inside the wall, so hopefully this one would also go easily.

I'll try this. I just don't want to sand too much, and end up making the pipe weak. It does seem like I should be able to sand just a bit more though, until the solder color is gone. The solder only bonds to the surface of the pipe, right? So the pipe should stay the same thickness as long as I only sand until the solder is gone.

This is the tool I have, love it -- as much as one that is starting to hate plumbing can love any kind of plumbing tool. At least with the masonry and woodworking projects I do, they will not flood my house if done incorrectly.
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On Oct 23, 12:57 pm, snipped-for-privacy@optonline.net wrote:

Usually you can just flux and reheat the pipe that has some solder left on it and use steel wool to scrub and wipe it off while molten. Pre-tinned the joints go together even easier. Try warming the pipe with the torch before dry fitting the parts, you would be amazed how much steam some condensation can make and it will push molten solder out of it's path.
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its not hot enough or not clean enough.
http://www.minibite.com/america/malone.htm
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On Oct 23, 11:13 am, snipped-for-privacy@surfbest.net wrote:

Gee it sounds like what you are doing is right, and the responses have been good. One more dumb question: while you are soldering, one end of the pipe is open to the air, right? (So pressure doesn't build up inside) -- H
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wrote:

Uhh, no! And maybe that is why I'm having so much trouble with this "last one", since all of the others wouldn't have this issue since the pipe was still open. However, I did do 2 temporary end caps prior to this part of the job, and those went on fine without anything "open".
Unless the fact that I have all of the nearby faucets open counts? This is for a shower faucet, and I have the sink faucet open (both hot and cold), and also sink and tub in the bathroom that shares a wall with this one, plus I have the hose open at the water shut-off valve coming in to the house... I just open all of those up because I want to make sure water is out of the lines, so I just leave them open, plus the water shut-off at the house has a tiny leak, and leaving these other faucets open keeps the pipes I'm working with free of water.
I guess I'll open the shower faucet I'm installing, since it can't hurt (unless I forget to close before I turn the water back on, then my wife gets wet since she stand in front of it with a 2-way radio to let me know if I need to turn the water back off in a hurry).
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snipped-for-privacy@surfbest.net wrote:

Are you absatively certain that the leak is occurring through the solder joint(s)?
I know you said you tried more than one elbow, but have you eliminated all possibilities that a pinhole NOT covered by solder might be leaking in such a way as to make it appear that the leak is coming through the solder joint.
You sound like a thoughtful, careful and conciencious guy, and I'm getting a feeling from your descriptions that just maybe you ARE making good solder joints on that elbow but something else is snookering you into blaming your soldering.
Maybe it's YOU who should be standing there observing while the little lady turns the water supply back on. You might spot something else that way.
Keep us posted!
Jeff
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Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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You've gotten lots of good advise but I'll add one trick taught me by Master plumbers. If you have ANY risk of water seeping toward your joint, you need to stop it far enough back and long enough to complete the solder joint.
The trick? Get a slice of white bread -- the doughier the better. Wad it up so that you can shove a bunch of it far down the pipe; a pencil makes a good ramrod. Make sure it fills the entire diameter of the pipe. Pack it in both directions if necessary. While you're soldering, the bread will absorb the water. When you turn the water on, the water will dissolve the bread and flush the pipe clean.
I had been soldering copper for decades and running into all sort of problems getting the last traces of water out of the pipe until I learned this trick. Believe me -- it works!
Best of Luck!
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Anyone else think this could be a trapped air problem? The more I think about it, just because I had some other nearby faucets open, I don't think that would release the air, and I really think I may just need to open the shower faucet (the one I'm installing, and this last elbow is on the supply side of that faucet). The more I think about it, it sure seems like it could be air, because the solder often looks like lava rock, instead of a nice smooth finish. I probably should have mentioned that earlier, but it doesn't always look that way, just on some of my attempts, but now I'm thinking even on the attempts where I got the visible part smooth, there could still be rough parts that I can't see (i.e.-lines/bubbles where the air is trying to pass).
My wife just told me she "heard air" everytime I turned on the water. Not sure exactly what to make of that.
I'll open the shower faucet on my first attempt tonight, AND also I'll be the one standing by the pipes while she turns on the water. Most of the time the leak was slow enough that I left the water on and looked for myself, and the leaks were coming from the joint, usually on one side of the elbow or the other, not something silly like them coming from the threaded joint (at the shower valve) and running along the pipe down to that spot.

Good to know.... although we rarely have plain white bread in the house, but I'm sure I could borrow a slice from a neighbor (wouldn't taste very good when I returned it though).
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snipped-for-privacy@surfbest.net wrote:

Nope. Trapped *air* is never a problem when soldering pipes; it just doesn't expand enough to cause any trouble, and the pressure isn't high enough to force it past melted solder. Trapped *water* is a problem, though: when it turns to steam, it occupies a thousand times the volume it did as water, and the pressure can be enough to blow a joint completely apart.

That's not from air coming out -- that's from steam.

steam
is passing

Doubtless you have air in the lines. But that's not relevant here: it's the water, flashing to steam, that's causing your problem.

Let the joints cool off longer, too, before you run water into them.

It doesn't have to be white bread. Whole wheat works just fine.
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Regards,
Doug Miller (alphageek at milmac dot com)
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Air gets into the water lines when you work on the pipes, and when you turn the pressure back on it blows out the faucets etc for a few minutes.. No problem.
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