For a true sanitary set-up, you will need at least one welded tri-clamp fitting.
Something like this:
http://www.mcmaster.com/#quick-clamp-tube-fittings/=d66uil
You can always put a threaded tri-clamp adapter through the kettle wall and build something bulkhead-like (which is what I did) but you kind of eliminate the real point of a tri-clamp system, because threads are not sanitary. However, you do have a heat tolerant QD system available to you, which is a really nice thing.
Here is the threaded adapter I used.
http://www.mcmaster.com/#quick-clamp-tube-fittings/=d66yy0
I like having SS tri-clamp fittings on my kettle because like I said, I use them like QD's. I can swap between hoses for transfers (with a tri-clamp x barb fitting) and tri-clamp 90's (to drain wort directly from kettle to carboy). I can also remove the valve very easily after brewing and clean and sanitize the whole thing.
Just be aware that tri-clamps are insanely expensive. I got the 1/2" BV on my kettle through my company, and it was still almost $70. I also bought the barbed adapter wholesale, and I think it was about $25. In addition, for just an adapter, and a valve, you will need a minimum of 2 clamps, and a small supply of gaskets - and that is just for the kettle. Like I said, it adds up quickly.
Joe
EDIT- And yes, there is steel tubing specific for tri-clamp fittings. However, you can use silicone hose with barb x tri-clamp adapters, but again, it will add up quickly. I'll take some pictures of my gear and post them tonight - it might help you understand the system and options if you had a good visual.