Find the plate first. It is a metal or durable plastic tag attached to the steel cage, usually on an upper horizontal member of one of the long faces. It is not moulded into the bottle — the bottle carries capacity, date and manufacturer markings only, which is a distinction worth holding onto because the two can tell you different things about the same unit.
The design type: four characters
Everything before the first slash is the design type code. It is read left to right and each position means something specific.
| Position | Example | Meaning | Other values |
|---|---|---|---|
| 1–2 | 31 | Rigid IBC for liquids | 11 = solids, gravity discharge; 21 = solids, pressure discharge |
| 3 | H | Plastic inner receptacle | A steel, B aluminium, N other metal, G fibreboard, L textile, M paper, D plywood |
| 4 | A | Steel outer frame | Z other outer material; omitted if no outer |
| 5 | 1 | Non-pressurised design | 2 = pressurised design type |
So 31HA1 is a rigid composite IBC for liquids, with a plastic inner receptacle and a steel outer frame, of non-pressurised design. That is the standard caged tote everybody pictures. The variants you will actually meet in a reclaimed population are a short list.
| Code | Contents | Inner | Outer | Typical unit |
|---|---|---|---|---|
| 31HA1 | Liquids | Plastic | Steel | Standard composite IBC |
| 31HZ1 | Liquids | Plastic | Other | Composite with non-steel outer |
| 31HZ2 | Liquids | Plastic | Other | Pressurised composite variant |
| 31H1 | Liquids | Plastic | None | Rigid plastic IBC, no cage |
| 31A | Liquids | Steel | — | All-steel, including stainless |
| 31B | Liquids | Aluminium | — | Aluminium IBC |
| 11HA1 | Solids | Plastic | Steel | Composite IBC for powders |
The packing group letter
A single character after the design type, and the one most worth checking against your own material.
- X — approved for packing groups I, II and III. The highest hazard approval.
- Y — approved for packing groups II and III. This is what almost every composite IBC carries.
- Z — approved for packing group III only.
If your material is packing group I and the plate says Y, that unit is not approved for it, regardless of its physical condition. An X-rated composite IBC is unusual; those materials are more commonly shipped in steel.
Date, state and manufacturer
- 01Manufacture date, as month and year — often shown as two pairs of digits, for example 03 25 for March 2025.
- 02State of approval, as a country code. This is the competent authority that approved the design type, not necessarily where the unit was assembled.
- 03Manufacturer mark and approval reference, which identifies the moulder and the specific design-type approval.
The numerical block
| Element | Example | What it limits |
|---|---|---|
| Stacking test load | 1800 | Permitted superimposed load during stacking |
| Maximum gross mass | 2418 | Your filled weight must not exceed this |
| Capacity | 1040 | Nominal capacity, usually in litres |
| Tare mass | 125 | Empty weight of the assembly as supplied |
Units vary between manufacturers — check whether the plate is in kilograms or pounds before doing arithmetic with these figures.
The maximum gross mass is the element most often overlooked and the easiest to breach. Multiply your capacity by 8.34 pounds per gallon, multiply by your product's specific gravity, add the tare, and compare. A dense product can exceed the marked gross mass well before the tote is physically full.
Reconditioning and periodic inspection markings
On used stock, this is the part that matters most and the part most often missing. A properly reconditioned unit carries additional marking identifying the reconditioner and the date of the most recent periodic inspection.
| Interval | Scope | What it covers |
|---|---|---|
| Every 30 months | External | Visual inspection, leakproofness test, service equipment, markings |
| Every 60 months | Full | Internal examination, leakproofness, structural assessment |
| After repair | As required | Inspection and test before return to regulated service |
An IBC used for hazardous materials transport whose periodic inspection has lapsed is not legally usable for that purpose, however good it looks. It remains perfectly usable for non-regulated liquids and for storage. Checking that date takes five seconds and is the single most useful thing on the plate.
The four things the plate does not tell you
This is where buyers get into trouble, because a valid marking feels like a complete answer and is not. A marking certifies that the design type passed drop, leakproofness, hydraulic pressure, stacking and vibration testing, and that this unit conforms to that design type. It says nothing about:
- 01Chemical compatibility with your product. This is always the filler's assessment and requires your product data, not the container's paperwork.
- 02Suitability for food contact. That is an entirely separate evidence chain — compliant resin, clean fill history, segregated handling and documentation.
- 03What was in it previously. The plate is silent on fill history. You need a previous-contents declaration, per unit.
- 04Whether it has been washed, or how. Again, a separate record — ask for the wash programme code.
A valid marking is necessary, not sufficient. Treat it as one of four documents you need, not as the answer to all four questions.
A thirty-second field check
- Design type matches the contents category — liquids versus solids
- Packing group letter covers your material's packing group
- Periodic inspection date has not lapsed
- Maximum gross mass exceeds your filled weight, calculated with your specific gravity
- A reconditioner mark is present if the unit is used and intended for regulated service
- The bottle's own date wheel is consistent with the story you have been told about the unit
Six checks, half a minute, and it will catch nearly every container-specification problem before it reaches a filling line. Photograph the plate while you are there — it is the fastest way to get a straight answer from a supplier about any unit.