Conversion. Beverage containers to aviation oxygen cylinders. Before completion of the fourth and final welding operation in the manufacture of shatterproof oxygen cylinders for high altitude flying, all straps are subjected to physical tests to determine the strength of the weld. Occasional radiographic inspections are made to insure the quality of workmanship after the two halves of the cylinder are brought together in this atomic welding machine and made one unit. Here, the operator has just completed the union and is about to remove the whole cylinder. Firestone, Akron, Ohio. Sourced from the Library of Congress.