49 CFR 178.33a-6 - Manufacture.
(a) By appliances and methods that will assure uniformity of completed containers; dirt and scale to be removed as necessary; no defect acceptable that is likely to weaken the finished container appreciably; reasonably smooth and uniform surface finish required.
(b) Seams when used must be as follows:
(1) Circumferential seams. By welding, swedging, brazing, soldering, or double seaming.
(2) Side seams. By welding, brazing or soldering.
(c) Ends. The ends shall be of pressure design.