Just want to give everyone a warning about bead blasting off galvanic coating. I took my little 4130 chromoly scuba tank to a powdercoater to have the zinc/galv blasted off. I had already cut the door out so the inside of the tank was exposed and blasted as well. Not sure if it was because he was using an enclosed recirculating media cabinet but what I thought was a clean surface was not! While prepping/grinding the areas where I would be welding I discovered that the galvy was still there. Either re-deposited into the metal from dirty media or the guy just did a poor job. It was deceiving as the tank "looked clean". I am now wet sanding the whole tank inside and out by hand.