Chapter 05 · UN / DOT marking decoder
Every character on that stamp is a legal claim.
The marking moulded or pressed into a tote's frame plate is not decoration. It states what the container is, what hazard class it may carry, when it was built or last reconditioned, who authorised that, and how much mass it may bear. Here is how to read it, field by field.
01 / DECODE
A worked example
Character-by-character breakdown
| Field | Example | Meaning |
|---|---|---|
| UN symbol | UN | Certified to the UN model regulations |
| IBC code, digit 1–2 | 31 | Type 31: IBC for liquids, filled or discharged by gravity or pressure |
| Material letter | H | Rigid plastics |
| Material letter 2 | A | With a steel outer frame (composite) |
| Structural digit | 1 | Fitted with structural equipment designed to bear stacking load |
| Packing group | Y | Approved for packing groups II and III |
| Date | 0326 | Month and year of manufacture or reconditioning — March 2026 |
| Country | USA | State authorising the mark |
| Maker / reconditioner code | TO-1184 | The registered code of whoever made or re-marked it |
| Stacking load | 2435 | Maximum permitted stacking load in kilograms |
| Maximum gross mass | 1041 | Maximum permitted gross mass in kilograms |
02 / TYPE CODES
The first characters
IBC type codes you will encounter
| Code | Container type | Typical use |
|---|---|---|
| 11 | Rigid IBC for solids, discharged by gravity | Powders, granules |
| 13 | Flexible IBC for solids | Bulk bags |
| 21 | Rigid IBC for solids, discharged by pressure | Pneumatic transfer |
| 31 | Rigid IBC for liquids | The caged composite tote we sell |
| HA1 | Rigid plastic with steel outer frame | Caged composite IBC |
| HB1 | Rigid plastic with aluminium outer frame | Lightweight variants |
| HZ2 | Composite with flexible inner receptacle | Specialist liquid |
| A | Steel | Steel IBCs and drums |
| B | Aluminium | Aluminium IBCs |
| N | Metal other than steel or aluminium | Rare |
03 / PACKING GROUPS
The letter
Packing group letters
| Letter | Packing groups | Hazard level | Note |
|---|---|---|---|
| X | I, II and III | High, medium and low | Not used for IBCs — IBCs are never PG I |
| Y | II and III | Medium and low | The normal marking on a composite IBC |
| Z | III only | Low | Seen on lighter-duty containers |
04 / WHEN A MARKING STOPS BEING VALID
Four ways a mark dies
- The date runs out of test cycle. Composite IBCs in regulated liquid service need periodic leak testing and inspection at intervals set by the regulation — generally a leak test every two and a half years and a full inspection every five. The date field tells you where you are.
- The container is modified. Cut a port, fit a manway, change the design type in any way, and the marking is void permanently. No test restores it. This is why our fabrication bay grinds marks off before the torch comes out.
- The marking becomes illegible. If a character cannot be read, the mark is not a mark. Faded, painted-over and gouged plates all fail.
- The cargo history is unknown. Not a regulatory rule but ours: we will not re-mark a container whose prior cargo we cannot document, even if it passes every test.
Who may apply a new marking
Only a registered reconditioner, after the container passes the applicable tests in 49 CFR 178.801. The new mark carries the reconditioner's code and the month and year of the work — which is why a re-marked tote shows a recent date on an obviously older container. That is correct and expected, not a red flag.
We perform this work in zone E. Details on testing & certification.
C / COMPATIBILITY
Will HDPE hold it?
Sixteen cargo families, rated
HDPE is brilliant at most things and hopeless at a few. Where the answer is C, we will point you at stainless rather than sell you a container that will craze.
| Cargo family | HDPE | Seat | Notes |
|---|---|---|---|
| Water, potable and non-potable | A | EPDM / silicone | Food-history units for potable |
| Acids and caustics, aqueous | A | EPDM / PTFE | Vent fuming cargo |
| Liquid fertiliser, UAN, NPK | A | EPDM | SG up to 1.32 — check your lift-gate |
| Brine and chloride de-icer | A | EPDM | Hard on galvanising, kind to HDPE |
| Food syrups, oils, concentrates | A | Silicone / Viton | Documented food history only |
| Glycols | A | EPDM | Very common; SG 1.04–1.11 |
| Alcohols | A | Viton / PTFE | Flammable — bond and vent |
| Diesel and gas oil | B | Viton / NBR | Permeates slowly over long storage |
| Mineral spirits | B | Viton | Swells HDPE slowly |
| Surfactants and detergents | B | EPDM | Odour fixation risk — dedicate units |
| Latex, adhesives, water-based paint | A | EPDM | Cures if left. Wash promptly. |
| Ketones, aromatics, chlorinated solvents | C | — | Crazes HDPE. Stainless only. |
| Gasoline and low-conductivity fuels | C | — | Static risk. Steel or stainless. |
| Essential oils, flavour concentrates | C | — | Fixes into the wall permanently. Never. |
| Hydrogen peroxide above 10% | C | — | Decomposition and pressure risk |
| Dairy and hot-fill above 140 °F | C | — | Needs CIP and steam. Stainless. |
Permeation
Small non-polar molecules pass slowly through HDPE rather than attacking it. The bottle looks perfect and your cargo quietly leaves. It is a storage-duration problem: diesel for a week is fine, diesel for a year is not.
Crazing
Ketones, aromatics and chlorinated solvents cause fine surface cracking that propagates under stress. It is invisible until you hold the wall against a raking light, and it is a critical grading failure.
Odour fixation
Terpenes and some surfactants dissolve into the polymer itself rather than sitting on the surface. No wash removes them. This is why a food-grade tote has to have been a food tote from new.
D / ORDERING
Commercial terms, up front
Lead times, minimums and what happens when it goes wrong
Discovering these at invoice stage is nobody's idea of a good relationship, so they are published.
| Item | Detail |
|---|---|
| Minimum order | One unit. No account minimum, no membership. |
| Stock lead time | Grade A and B 275 gal usually ship the same week |
| Rebottled lead time | 2–3 weeks, built to order in bay D |
| Food-grade lead time | 1–3 weeks when stock exists; supply-dependent |
| Full truckload | 45 on a 48 ft flat, 48 in a 53 ft van, 90 empties double-stacked |
| Payment, first order | Prepay by ACH or card |
| Payment, established | Net 30 on credit approval |
| Grade guarantee | Regrade or replace, our freight both ways, 14 days |
| Leak warranty | 30 days from delivery, normal atmospheric service |
| Cancellation | Free until the truck is loaded |
| Returns | 14 days on unused stock units, freight at your cost |
| Sales tax | Indiana resale certificates and out-of-state equivalents accepted |
F / END OF LIFE
Reuse first, recycle last
What happens when the container is finally finished
Every unit that arrives is assessed down this list, in this order. 99.4% of incoming mass avoided landfill in 2024, and reuse plus repair accounted for over three quarters of it.
| Step | Outcome | Share of mass | Cost to us |
|---|---|---|---|
| 01 | Reuse as is — wash and redeploy | 63.9% | 11 gal of mostly reclaimed water |
| 02 | Repair and reuse — valve, gasket, pallet, cage | 11.4% | Parts and bench time |
| 03 | Rebottle — new bottle, reclaimed steel | 9.6% | A new bottle, two thirds of mass retained |
| 04 | Upcycle — rain kits, grow beds, wash stations | 3.2% | Fabrication time |
| 05 | Material recovery — HDPE regrind, steel, wood | 11.3% | Grinding, washing, drying energy |
| 06 | Residual to licensed disposal | 0.6% | Sludge, gasket rubber, fasteners, laminates |
A / SPECIFICATION
Reference
Dimensions, fittings and seat materials
The three tables people actually need before ordering. Full versions, with pallet footprints, metric conversions and sixty-plus cargo entries, live in the size guide.
Fig. 1
Fig. 2| Capacity | Litres | Footprint | Height | Tare | Gross (water) | Stack loaded |
|---|---|---|---|---|---|---|
| 275 gal | 1,041 | 48 × 40 in | 46 in | ≈140 lb | ≈2,435 lb | 2 high |
| 330 gal | 1,249 | 48 × 40 in | 53 in | ≈155 lb | ≈2,905 lb | 2 high |
| 350 gal | 1,325 | 48 × 40 in | 56 in | ≈165 lb | ≈3,075 lb | 2 high |
| 120 gal | 454 | 40 × 32 in | 38 in | ≈95 lb | ≈1,095 lb | 2 high |
| 180 gal | 681 | 42 × 36 in | 42 in | ≈115 lb | ≈1,616 lb | 2 high |
| 550 gal | 2,082 | 60 × 48 in | 60 in | ≈240 lb | ≈4,830 lb | 1 high |
B / FITTINGS
What threads onto it
Fittings, threads and seat materials
| Fitting | Size | Seals by | Seat options | Typical service |
|---|---|---|---|---|
| S60x6 butterfly valve | 2 in | Flat gasket face | EPDM, Viton, PTFE | The standard IBC outlet |
| S70x6 butterfly valve | 2 in | Flat gasket face | EPDM, Viton | European and some 330 gal units |
| 2 in NPT ball valve, poly | 2 in | Thread flanks + tape | EPDM, Viton | Retrofits, metered dispensing |
| 2 in NPT ball valve, stainless | 2 in | Thread flanks + tape | PTFE | Solvents, pressure, hot cargo |
| 3 in butterfly valve | 3 in | Flat gasket face | EPDM, Viton | Viscous cargo, high flow |
| 6 in fill cap | 6 in | Gasketed lid | EPDM, silicone | Vented or solid — choose deliberately |
| Camlock adapter, type C | 1.5 / 2 in | Cam arms + gasket | Buna, Viton | Repeated connect / disconnect |
| Bulkhead tap | 3/4 in | Both-side gaskets | Brass, poly | Rain kits, site water |
| Material | Good with | Avoid with | Temperature | Cost |
|---|---|---|---|---|
| EPDM | Water, acids, caustics, brine, ag-chem | Oils, fuels, aromatics | -40 to 250 °F | Low |
| Viton (FKM) | Solvents, oils, fuels, aromatics | Ketones, amines, hot steam | -15 to 400 °F | High |
| Nitrile (NBR) | Oils, diesel, greases, hydraulics | Ozone, strong oxidisers | -30 to 250 °F | Low |
| PTFE envelope | Almost all chemistry, high purity | Needs very flat flange faces | -100 to 450 °F | High |
| Silicone | Food contact, wide temperature | Solvents, abrasion | -60 to 450 °F | Medium |
E / GRADING
A grade is a promise, not a mood
How every unit is scored
We publish the whole system because a grade without written criteria is just an opinion with a price tag. Nineteen points, fixed thresholds, one card per unit, seven years on file.
| # | Point | Critical? |
|---|---|---|
| 01 | Prior cargo declaration — present, written, specific | Yes |
| 02 | Residual liquid — any volume at all | Yes |
| 03 | Odour after wash — fixed odour by trained nose | Yes |
| 04 | Bottle corner stress whitening | No |
| 05 | Interior scoring you can feel | No |
| 06 | Interior crazing — fine surface cracking | Yes |
| 07 | Bottle bulge or deformation | Yes |
| 08 | Wall thickness at the thinnest point | Yes |
| 09 | Dome port condition and flange flatness | No |
| 10 | Outlet threads — cross-threading, chipping | Yes if crossed |
| 11 | Valve function, full open and close | No, replaceable |
| 12 | Gasket condition — compression set, bloom | No, replaceable |
| 13 | Cage squareness along the top rail | No, pressable |
| 14 | Cage weld integrity at tube intersections | Yes |
| 15 | Cage coating and galvanising loss | No |
| 16 | Pallet condition — cracked feet, rot, corrosion | No, replaceable |
| 17 | Forklift pocket integrity | No |
| 18 | UN marking legibility and date | No, re-markable |
| 19 | Leak test under our procedure | Yes |
G / PITFALLS
Learned the expensive way
Five mistakes that cost people money
Not hypothetical. Each of these has arrived in our inbox, usually more than once.
Ordering a 330 without measuring the ceiling
A 275 and a 330 share a footprint; the 330 is seven inches taller. Two 330s stacked is 110 inches against 96 for two 275s, and most sprinkler regimes want eighteen inches of clearance below the deflector. That seven inches is frequently the whole margin.
Forcing an NPT fitting into an S60x6 port
Both are roughly two inches, so it bites and feels tight. It is not sealing, it is chewing the buttress thread. The joint weeps two days later, usually in transit, and cross-threading is one of the few faults that condemns an otherwise perfect bottle.
Reusing a flange gasket
A gasket is a one-use part the moment it has taken a compression set. Reusing one is the cause of most 'the new valve still leaks' emails we get. They cost a couple of dollars. Keep a box at the fill point.
Specifying a solid lid on a tote that sees sun
Sealed container, rising temperature, nowhere for the expansion to go. The bottle bulges between the cage bars and does not fully return. A vented lid is the cheapest risk control in this industry.
Ignoring specific gravity
A full 275 of water is 2,435 lb. The same tote of UAN 32 is 3,168 lb, and a 330 is 3,785 lb. Plenty of lift-gates are rated at 2,500 or 3,000 lb, and the rating assumes a centred load.
Free decode
Paste the string. We will read it.
Send us the full marking from your tote and we will tell you what it permits and when it was last certified.