The defining characteristic of 7311 is that the container is specifically designed for compressed or liquefied gas, meaning it is pressure-rated and built to contain gas under pressure. Heading 7309 covers general-purpose tanks and reservoirs for liquids or non-pressurized storage. A standard atmospheric-pressure storage tank does not qualify under 7311 even if it occasionally holds gas.

Yes. Compressed gas cylinders intended for use in the US must generally comply with Department of Transportation (DOT) specifications or special permits governing cylinder design, testing, and marking. Importers should confirm that foreign-manufactured cylinders meet the applicable DOT specification or have an approved exemption before the goods enter commerce.