When I am soldering copper fittings sometime I run into a problem when I am doing some of the connections and I am looking for a solution. The problem occurs when the joint is in a closed system. I open all the valves closest to the area I am soldering but it seems that the solder does not get sucked into the joint. I get the joint definitely hot enough and am using flux of course. Most of my connections are not a problem but sometimes I run into this problem. I think it is because it is a closed system and maybe not enough air flow inside the pipe to create that suction. How do I solve this? I open the valves and taps in the areas but this does not seem to help. Eventually I get the job done but it does not come easy. How can I make this easier?

Thanks in advance.
Steve

Since none of the plumbing experts have answered this post as yet, I'll give it my best shot. I think your problem is the presence of water in the pipe which keeps the joint from getting hot enough. Try blowing compressed air into a nearby faucet to expel any remaining water. The flow of the solder is due to capillary action, not air flow. I have heard of plumbers shoving bread into the pipe to hold back the water to allow soldering of the joint.

Dr. D has made a good suggestion but we need to know a bit more about your skills. Do you understand that the flux is applied to both the male and female fitting before they slide together? It is also very important to sand or brush both pieces prior to flux. We used to use bread to stop up a dribble of water but now we use pellets that look like a vitamin C tablet.

Yes I flux both end of the pipe and steel wool all the connections.

Both ends is good but you did not mention the inside of the fittings, was that just an omission when you typed your answer?

I have soldered a lot of copper pipes -- other posters are 100% correct -- when you do it for a living you learn

I like applying heat on one side and solder on other -- and use damp rag to wipe off excess solder

I would recommend any of these sites -- last one is a good video

Copper in Your Home: Do It Yourself - Soldering School

http://www.rd.com/18276/article18276.htmlal

Soldering Copper Pipes Tutorial

Please rate my answer -- Thank You

Thanks for the advice. I clean all the fittings where ever they are joining (inside and outside of pipe) I almost always have not problems, it just seems once in a while the I run into this problem. The next time it happens I will look and see if water inside the pipe is an issue or not. Thanks for all your time.
Steve

Thanks for the advice. I clean all the fittings where ever they are joining (inside and outside of pipe) I almost always have not problems, it just seems once in a while the I run into this problem. The next time it happens I will look and see if water inside the pipe is an issue or not. Thanks for all your time.
Steve

Quote:

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Originally Posted by redjames

I get the joint definatly hot enough

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This is a pretty hard question to answer unless you can observe the methods being used. Noting the above quote, you can get the joint too hot and burn the flux. Heat the fitting and put you solder to the joint when the flux begins to run. Even a small amount of water will kill the joint of course. The last joint is often the most difficult because you have more pipe absorbing the heat. The last time I had a problem soldering I was there until 3 AM. It was in the basement of a 3 story home. I was inadvertently using an oily rag to wipe the pipe off and each time I tried and failed, it took an hour for the pipe to fully drain. We all have problems once and a while.

Red James:

There is no closed system when it comes to soldering... let me explain.

I know what you are talking about here... you set up to solder, open a couple valves, drain water, install pipes/fittings, and begin to solder... first few joints are good, then on last joint or two you go to close it up and solder just won't suck into joint... right?

I won't go into detail about what I think it is... what I will do is tell you how to prevent it from ever occurring again.. ok?

I tell all my apprentices... until they get all kinds of experience soldering I want them to do the following FOR MOST SOLDERING JOBS:

Shut off water main shutoff, then open up ALL faucets in the house and flush all toilets... open outside faucets, drain to laundry sink in basement or remove washing machine hoses and drain them into bucket.

Once all water is confirmed drained... all work can then be performed and will have NO ISSUES soldering.

If closed system for some reason... let's say between a shutoff and a check valve... then need to make sure the shutoff has a petcock (drain hole with cap on side of shutoff) so can release the pressure that builds as soldering.

That's the point here... if you are having trouble with those last joints or so, there is a problem releasing pressure either from heating excess water in system or from fact that air is being heated and cannot expand out of system (CLOSED) as joints get heated.

If you open all pipes, if you allow places for air to expand when soldering (shutoffs with petcocks), then soldering should not be an issue at those last couple joints.

Hope that helped some... Mark
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Thanks Mark, that explains a lot and was what I was thinking was happening. I did not think it had anything to do with cleaning the fittings etc. etc. because this only seemed to heppen on the last joint or so exactly what you are talking about. Next time I will take more time draining the system fully.
Thanks again,
Steve

Not an expert here. Just a diy'er.

Water has killed my joints before, even when I think I've drained enough out.

Oatey no.95 tinning flux with solder premixed into the flux, or the home depot presoldered fittings aren't bad. I've used both when I knew I had one shot to get it right and the space was confined. I don't usually buy the HD fittings, as id rather save money, but when I've used them some time back, they seemed to work nicely. I tend to still use oatey's 95... doesn't mean I don't also push some solder into the joint, but on one early home repair job where I just kept getting pinhole after pinhole, I used oatey's based on a plumbers recommendation and it worked like a charm.

Now... it obviously was my technique that was wrong... and I've since gotten better... but it was a nice crutch when I needed it.

All that said, I'm guessing water will be the death to all work if you aren't draining enough out.

Massplumber you are the great