B3 uses 18 gauge (.065"w) on their frames. I used 16 gauge (.083"w) on my 3 tier. If you are going to have your frame on casters it can't hurt to go a little on the heavy side. Less chance of burning through with the welder too.
Heros are made 10 gallons at a time.
Kegged/On Tap - Double IPA Conditioning - Orange Ale
I used a mix of 18 gauge stainless and 18 & 16 gauge steel on my stand. It was my first welding project also and found the 18 gauge material more forgiving to my newbie welding skills. It's also 1" square tube and I think it's more than strong enough and a lot lighter than 2" or 2.5" tube frame systems.
Iechyd Da Brewery www.mega-brew.com
Kegged & Drinking: Abbess Blonde, Irish Red, American Amber, Apfelwein, Liberty Pale, Belgian Wit, Barleywine
Upcoming: Black Pepper Pale Ale, Bleached Blonde Ale