Making hard line - fittings needed

[Farmerford]

JB:
Tommu56 has a good suggestion with one change. I used the Discound Hydraulics flareless fittings on 3/8" and 1/2" tube with great success. As you know from the Swage-Lok two ferrule fittings, the ferrules slip down around the tube and part way into the end fitting. The nut then pushes the ferrule down further into the fitting to swage it onto the tube. If you leave out the ferrule there will be a pretty big gap between the inside of the fitting and the outside wall of the tube. Melted silver solder or brass will pool in that space and probably leak into the fitting around the end of the tube.

But if you use the ferrule and nut, and then braze the nut/thread interface and nut/tube interface you will have a "double seal" that should solve your problems. Brass or silver solder should wick into the joints well enough to make everything tight.

And think of the looks you will get from your friends when they try to figure out why you welded the screw on fittings.