[Phil]

Adam
Awesome craftsmanship on those pipes, your welding and repeatability on the tubes is definitely on the money. If you are having some trouble with what you called "dirty" on the outside of the tubes I would suggest you try a complete purge during the process...an example would be a box similar to a glass bead cabinet, except for welding. We used this on titanium parts and it gave a good weld. Also you may have a little oxidation on those tubes which will also come to the top on stainless, looks like a floating skin as you weld. I can tell you that you have a superior product there and have taken pains in the details.
I would like to ask what method you use to cut the tubing to size as your join-ups look very good.
cheers
Phil