Aluminum cylinders are preferred in weight-sensitive applications such as medical, diving, and aerospace uses because they offer comparable pressure ratings at lower mass. For customs classification purposes, material (aluminum vs. steel) determines the heading — aluminum pressure vessels fall under 69244 while steel equivalents fall under 69243 — so the bill of materials must clearly identify the alloy.

Yes. The US Department of Transportation requires that cylinders used for compressed or liquefied gas bear specific markings indicating the applicable DOT specification, test date, and manufacturer identification. Importers should verify that foreign manufacturers are authorized to produce DOT-spec cylinders and that all required markings are present before the goods enter commerce.