Reading a UN mark
31HA1 decoded character by character.
29 terms
The words
of the trade
Container people use a private vocabulary and then wonder why buyers order the wrong thing. Here it is in plain English, with the practical consequence attached to each definition rather than left implied.
Order desk
Term missing?
If something we said on a quote made no sense, tell us the word and we will both define it here and stop using it without explanation.
The five words that matter most
Bottle and cage are the two halves of a composite IBC and they age at completely different rates, which is the whole basis of rebottling. Tare is the empty weight and it decides your truckload. Prior contents is the fact that determines grade, price and legal use. Stacking load is on the data plate and is not the same number as gross mass — confusing the two is how stacks fail.
A–VDefinitions
Glossary
- Bottle
- The blow-moulded HDPE inner receptacle of a composite IBC. It is the part that touches your product, the part that carries prior contents, and the part that retires first — typically after one to three service lives against the cage's four to eight.
See also: Cage, Rebottling
- Buttress thread
- The coarse, asymmetric thread form used on IBC outlets, designated S60×6 (60 mm nominal, 6 mm pitch) or S100×8 for large outlets. Designed to seal under load with a flat gasket rather than by thread interference.
- Cage
- The welded galvanised steel tubular frame surrounding the bottle. It carries all stacking and handling load, and it is essentially inert — cages die from forklift strikes, not from age.
- Camlock
- A cam-and-groove quick-connect coupling, types A through F. The standard way to get from an IBC outlet to a hose without threading anything. Type C (female coupler with hose shank) and type F (male adapter with male NPT) cover most IBC work.
- CIP
- Clean-in-place. Cleaning a vessel by recirculating hot detergent or caustic through a spray device without dismantling it. The only practical way to properly clean an IBC, given that a 6-inch lid offers no arm access.
- Creep
- The slow permanent deformation of a polymer under sustained load. In HDPE the rate roughly doubles for every 20 °F rise in temperature, which is why a tote stack that is stable in the morning can be spreading by mid-afternoon on a hot slab.
- Data plate
- The metal or moulded plate on the cage carrying the UN packaging code, manufacture date, stacking load, maximum gross mass and hydraulic test pressure. The closest thing an IBC has to a birth certificate.
See also: UN 31HA1
- First flush
- The initial runoff from a roof at the start of a rain event, carrying the accumulated dust, pollen, bird droppings and grit. A first-flush diverter captures and discards roughly the first two gallons before storage — the single highest-value component in a rainwater system.
- Food grade
- A provenance claim, not a cleanliness claim: one prior fill, that fill was an edible product, and there is documentation naming it. No cleaning process converts an industrial tote into a food grade one, because absorbed contaminants live inside the polymer rather than on it.
- Gasket
- The elastomeric seal between the valve and the bottle outlet, and the seal in the lid. Available in EPDM (water, caustics, alcohols), Viton/FKM (fuels, oils, solvents), silicone (food, heat) and Buna-N (petroleum oils). The most common cause of a 'leaking tote' is the wrong gasket material, and it is a four dollar fix.
- GMA pallet
- The 48 × 40 inch pallet footprint standard in North American grocery and general distribution. IBC totes from 110 to 350 gallons all share it, which is why a 330 drops straight into a 275's rack position.
- Gross mass
- The maximum permitted total weight of a filled container, stated on the data plate. Distinct from — and routinely confused with — the stacking load, which is what may be placed on top of it.
See also: Stacking load
- HDPE
- High-density polyethylene, resin identification code 2. The material of every IBC bottle. Excellent with water, caustics, acids, alcohols and detergents; poor with aromatic solvents, chlorinated solvents and strong oxidisers. Semi-crystalline and slightly permeable, which is why absorbed odours never fully leave.
- IBC
- Intermediate bulk container. A reusable container sized between a drum and a bulk tank, typically 275 or 330 gallons, designed for forklift handling and stacking. 'Tote' is the same thing in North American usage.
- LTL
- Less-than-truckload freight, priced per pallet position rather than by weight. Because totes cube out long before they weigh out, LTL is expensive per unit and rarely economic below six containers.
- Nominal capacity
- The rated working volume of a tote, distinct from brimful capacity. A '275 gallon' tote physically holds about 290 gallons; the difference is headspace for thermal expansion and it should not be filled into.
- Packing group
- The hazard tier a packaging design was tested against, marked on the data plate as Y (covers packing groups II and III) or Z (III only). Relevant to regulated transport, irrelevant to on-site storage.
- Rebottling
- Fitting a new virgin HDPE bottle into a reclaimed, straightened steel cage. Produces a container with no prior contents at roughly 60 percent of a new tote's price and 45 percent of its embodied carbon. The old bottle is granulated rather than discarded.
See also: Bottle, Regrind
- Reconditioning
- Returning a used container to service: interior and exterior wash, cage straightening, valve rebuild or replacement, new gasket, leak test and re-grading. An unregulated term in the trade, which is why any serious yard publishes its actual process.
- Regrind
- Granulated post-industrial plastic, typically produced to 3/8-inch particle size, sold as feedstock for pipe, pallet and drainage manufacture. Carries roughly a quarter of the embodied carbon of virgin resin — good, but far worse than not granulating the container at all.
- RTP
- Rigid tote pallet — the integrated pallet base of an IBC, available in composite, all-plastic or steel. Composite is standard; plastic suits wash-down and no-metal environments; steel takes forklift abuse and heat.
- Spray ball
- A fixed or rotating nozzle lowered through the lid to distribute cleaning solution across the interior wall. The correct tool for interior cleaning — as opposed to a turbo pressure-washer nozzle, which permanently scores the wall.
- Stacking load
- The maximum weight that may be placed on top of a filled container, stated in kilograms on the data plate. A rating of zero means the container is not designed to be stacked at all. Not the same as gross mass.
See also: Gross mass
- Tare
- The weight of the empty container. About 127 lb for a 275 gallon composite tote and 136 lb for a 330. Subtract from gross to get net product weight, and remember it when calculating a truckload.
- Tote
- North American usage for an IBC. Interchangeable in every practical sense, though 'tote' tends to imply the 275/330 gallon composite type specifically.
- Triple rinse
- Three separate fills of roughly ten percent volume, agitated and fully drained between each, with the valve open during at least one so the outlet dead leg is flushed. The baseline wash level, adequate for water-soluble residues.
- UN 31HA1
- The UN packaging code for a composite IBC with a rigid plastic inner receptacle and a steel outer casing, intended for liquids filled and discharged by gravity. 3 = IBC, 1 = composite, H = plastic inner, A = steel outer, 1 = liquids by gravity.
See also: Data plate
- UV embrittlement
- Degradation of HDPE by ultraviolet light, visible as a chalky white surface bloom and a loss of impact strength. Three uncovered Texas summers will do it. Shade, a cover or a black pigmented bottle prevents it; nothing reverses it.
- Valve, restricted flow
- A ball valve with a reduced bore, used where full-bore discharge would be unsafe or where dosing accuracy matters more than speed. Costs a few dollars more and prevents a specific category of accident.
?Common questions
Questions people actually ask
What is the difference between a bottle and a cage?
They are the two halves of a composite IBC. The bottle is the blow-moulded polyethylene inner vessel and the cage is the welded steel frame around it. They age at completely different rates, which is the entire basis of rebottling.
What does the UN marking 31HA1 actually mean?
Reading it in order: 31 is a composite IBC for liquids, H is plastics, A is steel outer, 1 means suitable for liquids. The rest of the string carries the test date, country of approval and stacking and gross mass figures.
Why does prior contents matter so much?
It is the single fact that determines grade, price and legal use. Contaminants absorb into the polymer wall rather than sitting on it, so no wash cycle converts an industrial container into a food one. No label means we refuse the container.
Is stacking load the same as gross mass?
No, and confusing the two is how stacks fail. Stacking load is what the container can carry on top of it; gross mass is what it may weigh when filled. Both are stamped on the data plate and neither substitutes for the other.
What is regrind and is it worth anything?
Granulated end-of-life polyethylene, sold by the pound back into non-food moulding. It is the least profitable material that leaves this yard, which is exactly why we would rather rebottle a cage than feed it to the granulator.
◆On the yard
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