When the Keebler Elves are done making cookies, they work nights supplying the world with triple flanged hoops. So elves make them. Really.
Probably starts out as a straight bar of steel. Then the flanges are imparted to the metal, then it's bent in a circle and joined. I totally made that up. I haven't the slightest clue how triple flanged hoops are made. They are probably stamped out by a 100 ton press because I never recall seeing any seams.
It is hard to see the welds, and most likely because there is a chrome or nickel plating over the flanged hoops, and they grind the welds smooth after they weld the ends together.
Looks closely on the inside of the hoop. You'll find evidence of welds that are ground down and then chromed.I have never noticed a joint on a triple flange hoop and don't think its roll forming.
More likely its stamped out of a sheet of metal.
It's not that much quicker, and it's A LOT cheaper to use dies and weld the joint than to press the whole thing and still need to roll the last bend in it.I'm going with the stamping process, but I'm still guessing. It's a lot quicker than welding each individual hoop.
Yup welded, could call it 'seamless' cuz you can't see the weld due to finishing.