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I have 3/4" copper pipe outdoors (backyard, above ground), and I am adding a couple tee fittings to branch to a different area. I am having a hell of a time getting the solder to melt. My next move is to skip solder and use sharkbite (expensive). Any ideas on why this is so difficult? Even if the pipe I'm working is removed from the system (thus, absolutely no water inside) still no luck.

  • I don't know the age of the pipe.
  • I'm using
    • Benzomatic propane (not mapp).
    • Benzomatic lead free plumbing silver bearing solid wire solder
    • Benzomatic lead free plumbing water soluble plumbing flux
  • The old pipes are green (oxidation), but I clean the joints with wire brush.
  • Fittings are brand new.

Edit: Yes, I'm heating the pipe joint and (trying) to apply solder on opposite side of heat. My first solder attempt a year ago was successful, main difference is indoor vs outdoor.

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    Are you heating the pipe up with the torch? "I am having a hell of a time getting the solder to melt" You heat the copper up to the point of being hot enough to melt the solder. Explain what you are doing. – Alaska Man Nov 28 '20 at 22:00
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    You need to heat the copper to point where it is hot enough to melt the solder. I've had problems using propane torches for this purpose, so bought a Mapp torch. Makes all the difference. Another thing that will impede the heating of the copper pipe is any kind of moisture in the pipe. Liquid water, even a little bit - forget about getting the copper hot enough. – SteveSh Nov 28 '20 at 22:25
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    The new lead free solder melts at a higher temp than the old lead based solder. MAPP gas (sometimes referred to as Map-Pro), burns hotter than propane and like SteveSh said, it makes all the difference in the world. Also, be sure your area to be soldered is clean (I think you mentioned that) and one thing a lot of people don't know is flux gets old and ineffective after a year or to of being opened. So make sure you have new flux as well. And like others have said, you heat the pipe enough so IT MELTS the solder, not the torch. It should be drawn into the joint. – George Anderson Nov 28 '20 at 22:37
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    You are not getting it hot enough. – blacksmith37 Nov 28 '20 at 22:56
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    @JimStewart it was a solder/flux kit with big blue letters that says PLUMBING – dabi Nov 29 '20 at 4:17
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The pipe must be cleaned until it is bright. A wire brush may not do the job well enough; I use a cloth-backed sand paper (aka emery cloth) for the job. It is about 1.5 inches wide and comes on a roll several feet long. I'm not a plumber but I use it routinely -- for your occasional or one-time use regular paper-backed sand paper would be fine as well. Maybe 80 grit or so.

Overheating the pipe is every bit as troublesome as underheating the pipe. If it gets overheated you may need to let it cool, then sand it and attempt again.

Make sure the socket of the fitting is clean too (and also not previously overheated). These are harder to clean well!

Open the gas valve on the torch so there's plenty of flame. It should make a good bit of noise and throw a tight blue cone of flame maybe 3-4 inches long.

I like to straighten out about 4 inches of solder from the roll, apply flux to both parts of the joint, assemble, and then hold the flame steady on one side of the pipe while occasionally touching the tip of the solder to the opposite side of the pipe. In other words, keep the solder away from direct exposure to the flame. When the pipe is hot enough to melt the solder remove the flame and continue applying droplets of solder into the joint. Add more heat only if the solder stops flowing before it has wicked all the way around the joint.

The truth is I've never used MAPP. Propane has always worked just fine for me. The torch head may make a difference though. I use a Victor TurboTorch similar to below. Been a long time since I watched a Bernzomatic torch burning but I think the TurboTorch makes a wider/larger flame. (image credit: manufacturer, www.esabna.com)

Victor TurboTorch

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    For cleaning pipe I use green scotch bright - like the kitchen cleaning things also for stubborn pipes I get the steel pan cleaners - not the very fine ones with soap in them but the ones tgat look like a ball of steel shavings. Both work well as they don’t leave gritty bits. – Solar Mike Nov 29 '20 at 5:29
  • Be careful not to overdo abrasion cleaning. A guy I knew told me he once removed so much copper that the solder could not fill the space. – Jim Stewart Nov 29 '20 at 16:56
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4 tips to soldering success.

  1. Physically clean - for copper, that's a bright shiny light-pink color, achieved through abrasive means. Even new fittings need to be cleaned - they are not shipped in oxygen-proof packaging.
  2. Chemically clean - flux.
  3. Hot enough to melt solder (the pipe, never apply the flame directly to the solder) - apply the flame to the joint and the solder to the joint away from the direct flame. When it starts to smear it's close.
  4. But not too hot or you'll burn the flux and oxidize the copper, at which point you need to take it apart and start over from point 1.

You're almost certainly at point 4 now, if you were trying and failing to melt solder for a while.

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  • Way better answer than my comment. Agree completely with your process! +1 – George Anderson Nov 29 '20 at 12:31

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