Every new IBC sold for hazardous-materials transport carries a UN rating sticker on the cage. Most people glance at it and assume it's either valid or it isn't. There's more to it.
Decoding the code.
- UN — United Nations recommendation, the international packaging standard.
- 31 — IBC for liquids. (30 is solids; 31 is liquids; 32 is solids under pressure.)
- H — Material code: H is plastic. A would be steel; B aluminum; M paper; N other metal; D plywood; F reconstituted wood; G fiberboard.
- A — Rigid plastic with structural equipment (the cage). HZ is composite plastic; for a typical caged IBC you'll see "HA1" with subscripts.
- 1 — Design type identifier.
- Y — Packing group rating: X covers Groups I, II, III (highest); Y covers Groups II and III; Z covers Group III only.
- Year & country — Year of manufacture and country code (USA, DE, etc.) follow.
- Specific gravity — A trailing number indicates the maximum specific gravity of contents the IBC was tested for (e.g., "/1.9" means tested up to SG 1.9).
- Hydrostatic pressure — Another number indicates test pressure in kPa (often 100 kPa for liquids).
UN ratings expire functionally after 5 years from manufacture for liquid transport (some jurisdictions, longer). For static on-site storage they don't expire at all. If you're shipping product in IBCs and crossing state lines with regulated material, check that your IBCs are within the 5-year window.