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Guide · Compliance
31HA1/Y/0326/USA/M1234 — every character, decoded.
The plate on the side of a rated IBC is the container's legal identity. It says what the container is, what class of danger it may carry, when it was built and who approved the design. Read it correctly and you can assess a container's regulatory status in about ten seconds. Read it wrong and you ship regulated cargo in something that is not approved to carry it.
Short answer
31 = liquid IBC · HA = rigid plastic inner with metal frame · 1 = design category · Y = packing groups II and III · 0326 = March 2026 · USA = approval country · M1234 = manufacturer reference.
- Type code
- 31
- Composite
- HA1
- PG letters
- X / Y / Z
- Test
- 2.5 & 5 yr
Form 01 · Spec request
Photograph a plate, send it over.
We read design-type markings daily. Describe what you can see in the message field and we will tell you what the container is approved to carry and what testing is due.
Segment by segment
The marking, taken apart.
| Code | Meaning | Common on |
|---|---|---|
| 11 | IBC for solids, filled or discharged by gravity | Bulk powder and granule containers |
| 13 | IBC for solids, filled or discharged under pressure | Pneumatic transfer units |
| 21 | IBC for solids, filled or discharged under pressure | Specialist solids handling |
| 31 | IBC for liquids | Every liquid tote on this site |
| Code | Construction | Notes |
|---|---|---|
| A | Steel | 31A is an all-steel IBC, including most stainless vessels |
| B | Aluminium | Uncommon in general industry |
| H | Rigid plastic | 31H1 is a plastic IBC with structural equipment |
| HA1 | Composite: rigid plastic inner, outer steel frame | The standard composite tote |
| HZ2 | Composite: flexible inner, outer casing | Less common |
| N | Metal other than steel or aluminium | Rare |
| Letter | Approved for | Danger level | Practical meaning |
|---|---|---|---|
| X | Packing groups I, II and III | High, medium and low | Highest approval; may carry anything the type allows |
| Y | Packing groups II and III | Medium and low | The most common rating on composite IBCs |
| Z | Packing group III only | Low | Limited approval |
| Segment | Example | Meaning |
|---|---|---|
| Date | 0326 | Month and year of manufacture — March 2026 |
| Country | USA | State that issued the design-type approval |
| Manufacturer reference | M1234 | Approval holder or manufacturer code |
| Stacking test load | e.g. 2500 kg | Load the design was tested to when stacked |
| Maximum permitted gross mass | e.g. 1135 kg | The rating you must not exceed when filling |
| Test pressure | e.g. 100 kPa | Where applicable to the design |
What the marking does not tell you
A design-type marking records what the container was approved as when it was built. It does not tell you whether the container is currently fit for regulated service. That depends on two further things: whether the periodic testing is current, and whether the container has been damaged or repaired in a way that departs from the approved design.
This is the distinction that trips people up. A tote can carry a perfectly legible 31HA1/Y plate from 2014 and be entirely unusable for regulated cargo because its periodic test lapsed a decade ago. The plate is necessary but nowhere near sufficient.
Testing intervals
For composite IBCs carrying regulated liquids, the general requirement is a leakproofness test together with an external inspection at intervals not exceeding two and a half years, and a full periodic inspection — which includes that test plus internal and functional checks — at intervals not exceeding five years from the date of manufacture and from each subsequent periodic inspection.
Specific requirements vary by jurisdiction, transport mode and cargo. Treat the above as orientation and verify against the current regulation that applies to you. We carry out testing and re-marking in house and issue records against each serial number.
Protect the plate
The single most avoidable way to destroy a rated container is to make its marking unreadable. Painting over it, applying a label across it, or aiming a pressure washer at it at close range will all do the job. Once the marking is gone, the container is permanently out of regulated service — a $200 asset reduced to a water tank by a careless afternoon.
Inspection
Reading a plate in the field
- Find the plate — usually on the cage frame near a corner, sometimes moulded into the bottle
- Photograph it square-on in good light before you touch anything
- Transcribe the full string, including the gross mass and stacking figures
- Check the manufacture date against the five-year periodic clock
- Look for a separate test date marking applied at the last periodic inspection
- Check the cage and bottle for repairs that would depart from the design type
Questions
Markings, answered
01What does 31HA1 mean?
31 means an IBC for liquids filled or discharged by gravity or pressure. H means rigid plastic. A means an outer metal frame. 1 identifies the specific design category. Together: a composite IBC for liquids with a plastic inner receptacle and a metal outer casing — the standard tote.
02What does the Y mean?
It is the packing group letter. X approves the design for packing groups I, II and III; Y for II and III; Z for III only. A Y-rated container may carry medium and low danger cargo but not high.
03How do I find the manufacture date?
It appears as month and year within the marking, usually as four digits such as 0326 for March 2026. That date starts the five-year periodic inspection clock.
04What if the plate is unreadable?
The container cannot be recertified for regulated service. It can still be sold, reconditioned and used for non-regulated cargo, but its rated life is over. This is why painting over or pressure-blasting a plate is such an expensive mistake.
05How often must a rated IBC be tested?
A leakproofness test and external inspection at intervals not exceeding two and a half years, and a full periodic inspection including that test at intervals not exceeding five years. Verify against the current regulation applicable to your jurisdiction and cargo.
This page is general guidance, not regulatory advice. Requirements differ by jurisdiction, transport mode and cargo. Always verify against the current applicable regulation before shipping regulated material.
Keep reading
Full code reference
Every segment, every value.
Enough to decode any IBC marking you are handed, and to know immediately what you are allowed to do with the container.
| Code | Contents | Fill and discharge | Where you meet it |
|---|---|---|---|
| 11 | Solids | Gravity | Bulk powder and granule |
| 13 | Solids | Under pressure | Pneumatic transfer |
| 21 | Solids | Under pressure | Specialist handling |
| 31 | Liquids | Gravity or pressure | Every liquid tote |
| Code | Construction | Full example | Repairability |
|---|---|---|---|
| A | Steel | 31A | Weld repair by a competent welder |
| B | Aluminium | 31B | Uncommon |
| H1 | Rigid plastic, with structural equipment | 31H1 | Limited |
| H2 | Rigid plastic, freestanding | 31H2 | Limited |
| HA1 | Composite: plastic inner, steel outer | 31HA1 | Cage repair routine, bottle replaceable |
| HZ1 | Composite: flexible inner, rigid outer | 31HZ1 | Varies |
| HZ2 | Composite: flexible inner, flexible outer | 31HZ2 | Varies |
| N | Metal other than steel or aluminium | 31N | Rare |
| Letter | Packing groups | Danger level | What it permits |
|---|---|---|---|
| X | I, II and III | High, medium and low | Anything the type allows |
| Y | II and III | Medium and low | The most common IBC rating |
| Z | III only | Low | Limited approval |
| Test | Interval | What it involves | Marked? |
|---|---|---|---|
| Leakproofness with external inspection | Not exceeding 2.5 years | Sealed, pressurised, held and checked | Date marked on the unit |
| Full periodic inspection | Not exceeding 5 years | The above plus internal and functional checks | Date marked on the unit |
| From date of manufacture | Both clocks start here | The plate date | On the plate |
| From each subsequent periodic | Both clocks reset | The last test date | Marked on the unit |
Intervals and requirements vary by jurisdiction, transport mode and cargo, and they change. This page is orientation for assessing a container quickly, not a substitute for the current regulation applicable to your shipment.
Next step
Send a photo of one plate.
Design type and date are enough for us to tell you what an entire fleet is approved to carry and what testing is due.