A UN/DOT marking such as 31HA1/Y describes the container type, materials and the hazard packing groups it is certified for. The leading 31 means a rigid composite IBC for liquids; HA1 identifies an HDPE bottle in a steel frame; and the Y indicates approval for Packing Groups II and III.
Read on for the full breakdown.
Why the marking exists
When a tote carries a regulated substance, transport law requires proof the container was tested to hold it safely. The UN marking is that proof, stamped or plated onto the cage. It is not marketing — it is a certification with a testing regime behind it.
Reading the code
Take a common example, 31HA1/Y/… and break it into pieces:
- 31 — rigid IBC intended for liquids (11 would be for solids discharged by gravity)
- H — plastic material for the inner receptacle
- A — steel for the outer frame (the cage)
- 1 — a composite IBC with a rigid inner container
- Y — approved for Packing Groups II and III (medium and low hazard)
Packing groups in plain terms
Packing Group I is high hazard, II is medium, III is low. An X-rated container covers all three; a Y covers II and III; a Z covers III only. Match the rating to your product’s classification — never above it.
The date matters
UN-marked IBCs carry a manufacture date, and for regulated transport they require periodic inspection and retesting (typically every 2.5 and 5 years). An expired test date can ground a shipment even if the tank looks perfect. Always check the date plate before relying on a rating.
When you do not need a rating
Storing non-regulated liquids on your own site — water, many detergents, food products — usually does not require a UN rating at all. Reserve rated (and pricier) tanks for the shipments that legally demand them.
Published August 30, 2023 · By IBC Solutions Illinois