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I am trying to open up some solder joints on a 1/2" residential cold water line, and I am having trouble doing so. I am using a propane torch, and I confirmed that the pipe was evacuated. My brother says that some plumbers use solder with a higher melting point and MAPP gas. Is this true? The concept of this seems like a bad idea for so many reasons and I'm concerned about burning a hole in my pipe. I also don't like the idea of using a much dirtier gas indoors. Is MAPP gas the way to go, or should I try something else?

mreff555
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  • also be aware the torch head makes a huge difference. I was using a $15 basic click start head and it would take a minute to get a pipe hot enough to solder. It was difficult on pipes mounted in place. I switched to a nicer torch (TS4000) and it gets the pipe hot enough to solder in seconds. – rpmerf Jun 06 '16 at 13:23
  • I have no idea what kind of solder was in that joint but even mapp gas wouldn't melt it. I ended up just cutting that leg off and re-doing a small portion of it. – mreff555 Jun 06 '16 at 13:28

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If it is copper pipe and was indeed soldered (using a tin-lead alloy or a more modern lead-free solder), then propane should work okay. However, MAPP (originally methylacetylene-propadiene propane but now stabilized liquefied petroleum gas with propylene) will heat faster and, with a common sense caution, not melt the pipe. That is, don't heat the pipe until it is yellow hot; red or orange is fine.

If the pipe was brazed with silver solder, which is common in HVAC systems, propane is not enough: you have to use MAPP to get it hot enough to work.

Propane and MAPP both burn completely. You need not worry about the exhaust: in all cases the result is water vapor and carbon dioxide. Just like when animals exhale.

wallyk
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  • I'm still not buying the complete burn with MAPP, but then again I haven't used it in 10 years or so. If it's just LPG and propylene now, I guess that makes sense. Thanks for the advice. – mreff555 Jun 04 '16 at 19:19
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MAPP gas is the way to go. It burns hotter, so It will heat the pipe faster. It will even heat the pipe if there's a bit of water in the line, something that propane will not do.

If you're worried about burning surrounding materials, you can use a heat shield.

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There are all different types, sizes, and styles from many different manufacturers. This is just one example.

Tester101
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Contrary to a good friend's advice, who was a plumber, I've several times used oxy-acetyline (as in car body welding, etc.) even on pipes still containing water,and as long as I wait until the solder melts, that's as long as the heat needs to be there. MAPP seems to be close to that, so should do the job. But - I've been welding for many decades.

Tim
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i would say that regular propane gas,use flux,heat it evenly and the solder wil get to meltin and flow i have used it before and just make sure you stuff some light bread in the pipe to keep the water from dripping,since you already have the mapp dont get it to hot keep the flame a distance

jerry haney
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  • And be careful not to toast the bread inside the pipe. :-) – Michael Karas Jun 04 '16 at 15:40
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    ... surely you didn't mean "bread"? Sealing food into a water pipe seems like a many-splendored bad idea. – Daniel Griscom Jun 04 '16 at 18:49
  • @Daniel Yes. thats what recommended, its melting in the water thereafter – aofkj Jun 07 '16 at 16:16
  • @aofkj Boy, I hope that if my plumber does this he never tells me about it... – Daniel Griscom Jun 07 '16 at 17:38
  • @Daniel As long as your shower is still working you shouldn't be worried even if he tells it to you:-) – aofkj Jun 07 '16 at 21:15
  • @DanielGriscom - it's a time-honoured way to keep drips of water at bay, and can't have been a problem, otherwise we'd all know about that. – Tim May 31 '21 at 10:54
  • I just did some googling about this, and the critical comment I found was [here](https://www.ridgidforum.com/forum/mechanical-trades/ask-the-plumbing-experts/10750-help-bread-in-water-line): "The idea with the bread is to use just enough to soak up the drip while you quickly solder." So, we're in no way thinking the bread would block the pipe; it's just there to absorb a bit of water while you solder. – Daniel Griscom May 31 '21 at 15:20