Sweat 3" Copper With Mapp Gas Torch?
You might have luck using two brazing torches, like these. My concerns usually aren't about making a mess; it's getting it to work without burning holes in it and physically getting it back together after a de-solder. I'd start over, but it's worth a shot on a $20 fitting. I'd say my re-solder success rate is 50\50 without doing more work than just using new, clean fittings. I've never done 3" and I wouldn't without a wrap-around torch head for an acetylene kit.

These brazing heads really are nice and make quick work out of plan old soldering.


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