I just wanted to share my soldering experience. After reading this thread I decided I would give it a shot. I used silver plumbing solder and liquid flux I picked up from the hardware store (Menards), so nothing fancy. I sanded the inside and outside of the keg and cleaned all pieces with acetone. Now I have soldered less than 4 times my entire life and using my Benzomatic propane torch I was able to solder in a 1/2 inch brass coupling with no leaks. I then picked up my keggle by the connection and swung it around my shed, it is not going anywhere. I want to thank all who posted advice. To anyone who wants to try this I cannot vouch for long term but my first observations would indicate an extremely strong bond.