Solder or brazing would be my first choice, but if you roughen up the opposing surfaces for a good "bite", JB weld would be a decent alternative. I used it on a diesel fuel return line fitting that came loose (it was pressed in place). I filed some grooves around the tube and also ran a tap a short distance into the fitting to give the JB something to grab on to. Cleaned it up with solvent and glued it back together. It's been hanging on for at least 5 years and possibly 10 years now.
