If you're buying an IBC tote to move a regulated material, the most important thing on the tote isn't the tank or the cage — it's the UN marking stamped or molded onto it. That string of letters and numbers is a packaging certification. It tells a shipper, a carrier, and a regulator that this specific design was tested and is authorized to carry hazardous materials in commerce. Buy the wrong marking, or one whose retest date has lapsed, and the tote is not legal to ship hazmat in — regardless of how good it looks.
Key takeaways
- A compliant IBC for hazmat service carries the UN packaging symbol followed by an IBC code (for example, 31HA1), packing group, gross mass, and a sequence of test data.
- The first digit is the IBC type and the letter is the material: A = steel, B = aluminum, H = rigid plastic, and HZ = composite (the common plastic-bottle-in-cage tote).
- Hazmat IBCs require periodic inspection and retest — commonly a 2.5-year and 5-year cycle — and the most recent retest date is part of the marking.
- For non-regulated contents (water, many food-adjacent or industrial liquids), the UN marking is not a legal gate, so the used-IBC market is far more flexible.
What the UN marking actually is
Intermediate bulk containers used to transport dangerous goods are regulated in the United States under the U.S. DOT Hazardous Materials Regulations (49 CFR), which adopt the UN performance-packaging standard. Rather than dictating exactly how to build a tote, the standard requires each design type to pass a battery of tests — drop, stacking, leakproofness, hydraulic pressure, and (for some) vibration. A tote that passes earns a marking that encodes what it was certified to carry. The marking is the proof; without it, a tote is just a container.
Decoding the code, element by element
A typical marking reads as a UN symbol followed by something like 31HA1 / Y / 1500 / 100 / 24 / USA / +maker info. Each block is a separate piece of data. Read left to right:
Element | Example | What it means |
|---|---|---|
UN packaging symbol | the circled-u / “un” mark | Certifies the design meets the UN performance-packaging standard. Without it, the rest of the marking is meaningless. |
IBC code — type | 3… | First character is the kind of container. 3 designates an IBC (as opposed to other UN packaging types). |
IBC code — material | …1HA… | Letter gives the body material: A = steel, B = aluminum, H = rigid plastic, and HZ = composite (rigid plastic inner inside a metal cage — the familiar 275/330-gallon tote). |
IBC code — contents/design | …1 | Trailing digit indicates intended contents: 1 for liquids, 2 for solids. The middle digits/letters describe the design category. |
Packing group | X, Y, or Z | Highest hazard level the IBC is approved for. X = PG I/II/III (most hazardous), Y = PG II/III, Z = PG III only. An X tote can carry what a Z tote can, but not vice versa. |
Maximum gross mass | 1500 | Maximum permitted gross mass in kilograms (tote plus contents) for solids/stacking, where applicable. |
Test pressure / specific gravity | 100 | For liquids, the hydraulic test pressure in kPa and/or the maximum specific gravity the design was tested against. |
Year of manufacture | 24 | Last two digits of the year the IBC was made. Sets the clock for the periodic-retest schedule. |
Country of authorization | USA | State that authorized the marking (the ISO country code). |
Manufacturer / approval ID | maker code | Identifies the manufacturer and the design-type approval, so the certification can be traced. |
The UN marking on an IBC, decoded
So a tote stamped 31HA1 is an IBC (3), rigid-plastic bodied with a steel jacket/structure in the composite family — read the full code, but in plain terms the letters and digits together tell you material and that it is rated for liquids (the trailing 1). A pure composite plastic-in-cage tote is usually marked 31HZ1. Always read the actual characters on your tote rather than assuming.
Regulated vs. non-regulated service
Whether the marking is a hard requirement depends entirely on what you put in the tote:
Regulated (hazmat) service — flammables, corrosives, oxidizers, toxics, and other dangerous goods. The UN marking is mandatory, must match or exceed the material's packing group, and the retest date must be current. This is where the rules bite.
Non-regulated service — water, many cleaning concentrates, non-hazardous industrial liquids, and food-adjacent products that aren't dangerous goods. Here the UN marking isn't a legal gate, so condition, cleanliness, and prior contents drive your decision instead. (Food contact has its own separate rules — see the food-grade guide below.)
Periodic inspection and retest
A hazmat IBC isn't certified forever. Metal, rigid-plastic, and composite IBCs in regulated service must be inspected and tested on a recurring schedule, and the dates get recorded on the tote. The standard framework most operators work to:
Every 2.5 years — an external visual inspection plus a check of service equipment (valves, gaskets, fittings) and, for metal/composite IBCs intended for liquids, a leakproofness test.
Every 5 years — the full periodic test, including the internal/external inspection and the leakproofness test, after which the new retest date is marked.
Treat these intervals as the standard framework, not gospel for your exact situation — the applicable test, who may perform it, and the recordkeeping all live in 49 CFR, and they can change. Confirm the current rule for your material and IBC type with PHMSA or a qualified hazmat specialist before relying on a date stamped on the cage.
Reconditioned and remanufactured IBCs
Used IBCs are widely reconditioned (cleaned and restored to their original design type, keeping the same UN marking) or remanufactured (rebuilt — often a new inner bottle in a reused cage and pallet). When a composite IBC is remanufactured, it is re-marked to reflect the rebuild, and the remanufacturer's mark and date become part of the certification trail. A legitimately reconditioned or remanufactured tote can carry hazmat — but only if its marking is intact and its retest is current. A “rebottled” tote sold without proper re-marking is a red flag for regulated use.
Why a hazmat buyer must check the marking and retest date
For regulated freight, the marking and the retest date are the difference between a compliant shipment and a violation. A carrier can refuse the load; a regulator can fine the offeror; and in an incident, an out-of-test or wrongly-rated IBC undermines your entire dangerous-goods program. Before you buy a tote for hazmat service:
Confirm the packing group letter (X/Y/Z) covers your material.
Confirm the contents digit (1 for liquids) and the tested specific gravity / pressure suit your product.
Read the most recent retest date and make sure it won't lapse before you've used the tote.
Make sure the marking is legible and original — not painted over or ground off.
For a broader look at construction, sizes, and capacities, see the IBC tote guide. If your contents touch food, the marking rules are separate from food-safety rules — read food-grade packaging standards as well. And to gauge what used totes trade for, check the IBC tote price index.
Frequently asked questions
What does the IBC code 31HA1 mean?
Read left to right: 3 designates an IBC, the letter gives the body material (A = steel, B = aluminum, H = rigid plastic, HZ = composite), and the trailing 1 means it is rated for liquids (2 would be solids). The full marking around it adds the UN symbol, packing group, gross mass, test pressure, year, country, and manufacturer. Always read the actual characters stamped on your tote.
Do all IBC totes need a UN marking?
No. The UN marking is required only when the tote is used to ship a regulated (hazardous) material under 49 CFR. For non-regulated contents like water or many non-hazardous industrial liquids, there is no UN-marking requirement, so condition and prior contents matter more than the certification.
How often must a hazmat IBC be retested?
The standard framework is an inspection roughly every 2.5 years and a full periodic test roughly every 5 years, with the latest date marked on the tote. The exact required test, who may perform it, and the recordkeeping live in 49 CFR and can change — verify the current rule with PHMSA or a qualified hazmat advisor for your specific material and IBC type.
Can a reconditioned or remanufactured IBC still carry hazmat?
Yes, if it's done properly. A reconditioned IBC keeps its original UN marking; a remanufactured one (for example a new inner bottle in a reused cage) is re-marked to reflect the rebuild. Either can carry hazmat only when the marking is intact, the packing group covers your material, and the retest date is current. A rebottled tote sold without proper re-marking should not be used for regulated service.