40 year old copper to new

[scratching my head]

I've really never had a problem with sweating joints before, but this one's kicking my tail. Short story - trying to repair leak in slab foundation. 3/4 inch copper. Cleaned old copper to "like new". Tried propane, and Mapp, but cannot get it to seal. I believe that all of the moisture is out, so don't think it's that. Someone told me to Silver solder it. Will mapp be hot enough? I saw a combo Mapp and oxygen system at Home Depot. Hot enough? HELP!!!!!!!!!!!!!!!!!!!

[SSN596]

An undergroung joint should be brazed rather than soft solder. MAPP + O2 should do it.

[scratching my head]

Thanks very much!

[LazyPup]

Copper joints made underslab within the confines of a structure are rquired to be made by means of wroght-copper fittings and brazed joints. The regular copper fittings may not be used.

Ref. IRC 2904.16.1 & UPC 316.2.1