I've never tried. I have, however, soldered a few connections together, including many in my hydronic heating system and quite a few in the plumbing.
Just clean the surfaces to be joined, with a wire brush or steel wool, put the flux on them and stick them together, then heat them up with a torch to well beyond ouch-hot and allow the solder to wick its way into the space between the metal of the two parts being joined.
The solder will even flow up against gravity through capillary attraction. If your metal is clean you should get good coverage and no leaks.
I did mean solder, but you need to use a torch for that as well and was what I meant. I don’t play with fire well.