Bitumen is not a flammable liquid in the way petrol is. It is not toxic, not corrosive, and not an oxidiser. Yet moving it at 160°C makes it one of the more demanding cargoes in bulk logistics, and the regulations reflect that.
The reason is heat. Under international dangerous goods regulations, a substance that would otherwise be unregulated becomes a Class 9 dangerous good purely because of the temperature it is carried at. That is the logic behind UN 3257, and it is the number most operators shipping hot bitumen will see on their paperwork.
This guide explains what Class 9 covers, why UN 3257 exists, when bitumen falls under UN 1999 instead, and what each classification requires in practice. It is a companion to our broader overview of hazardous material codes and the IMDG framework.
What are Class 9 dangerous goods?
Class 9 dangerous goods are substances and articles that present a hazard during transport but do not meet the criteria of any of the other eight classes. It is the miscellaneous category, defined by exclusion rather than by a single shared property.
The nine classes under the UN Model Regulations are grouped by hazard type. Class 1 is explosives, Class 3 is flammable liquids, Class 8 is corrosives, and so on. Each has a test-based definition. Class 9 catches everything that is genuinely hazardous in transit but does not fit those definitions.
That makes Class 9 unusually broad. A lithium battery, a bag of dry ice, an environmentally hazardous substance and a tank of hot bitumen are all Class 9, and they have very little in common beyond the classification.
Examples of Class 9 dangerous goods
Common Class 9 entries include:
- Lithium batteries (UN 3480, UN 3481 and related entries)
- Elevated temperature substances (UN 3257 for liquids at or above 100°C, UN 3258 for solids at or above 240°C)
- Environmentally hazardous substances (UN 3077 solid, UN 3082 liquid)
- Dry ice, listed as carbon dioxide solid (UN 1845)
- Asbestos (UN 2212 amphibole, UN 2590 chrysotile)
- Genetically modified organisms and micro-organisms (UN 3245)
- Dangerous goods in apparatus or machinery (UN 3363)
- Magnetised material carried by air
Two of those come with significant qualifications. Dry ice is largely exempt from ADR road carriage under special provision 593, while remaining fully regulated by sea and air. Lithium batteries have had their own label, Model No. 9A, since ADR 2023, so they no longer carry the plain Class 9 label described below.
The practical consequence is that “Class 9” on its own tells you very little. The UN number is what carries the meaning, and it is the UN number that determines packaging, tank specification, marking and documentation.
What is UN 3257?
UN 3257 is the entry for ELEVATED TEMPERATURE LIQUID, N.O.S., at or above 100°C and below its flash point (including molten metals, molten salts, etc.). It is assigned to Class 9, Packing Group III, with classification code M9.
Two conditions have to be met. The substance must be at or above 100°C when offered for carriage, and it must be below its flash point at that temperature. If it were at or above its flash point it would be classified as a flammable liquid instead, under UN 3256.
“N.O.S.” means not otherwise specified. It is a generic entry, used where a substance has no dedicated UN number of its own and is hazardous only because of how hot it is.
Under ADR the entry is split across two rows of Table A according to filling temperature, one for loads filled at not more than 190°C and one for loads filled above 190°C. Both are Class 9, Packing Group III, and both carry tank code LGAV. The higher temperature row adds further provisions covering thermal insulation and the design of the tank’s safety devices. The hazard identification number displayed on the orange plate is 99.
Why hot bitumen ships under UN 3257
Penetration grade bitumen is handled at roughly 140°C to 180°C depending on grade and application. At those temperatures it sits comfortably below its flash point, which is typically well above 230°C. It is not flammable at handling temperature, not toxic and not corrosive. Stationary and cool, it would not be regulated as a dangerous good at all.
What makes it hazardous in transit is thermal energy. A release of bitumen at 160°C causes immediate and severe burns, and it carries enough stored heat to ignite surrounding material. The regulations respond to that risk by classifying the heat itself, which is what UN 3257 does.
The same entry covers other hot cargoes handled in the same way, including molten sulphur, certain heavy fuel oils carried hot, and molten salts and metals.
Our guide to how bitumen reaches the road covers the temperature control side of this in more detail, including what goes wrong when heat is lost in transit.
When bitumen is not Class 9: UN 1999 and cutbacks
Not every bituminous product travels under UN 3257. The classification depends on the product, not the material family.
UN 1999 is the entry for TARS, LIQUID, including road oils, and cutback bitumens. It is assigned to Class 3, flammable liquids, and carries Packing Group II or III depending on the properties of the specific blend.
The distinction is flash point. Cutback bitumen has been blended with a petroleum solvent to reduce its viscosity so it can be applied at lower temperatures. That solvent lowers the flash point, often to 60°C or below, which brings the product within the Class 3 definition. Class 3 is defined by a closed cup flash point of not more than 60°C. At that point the product is a flammable liquid and is regulated as one, regardless of the temperature it is carried at.
A common error worth correcting. Because UN 1999 has “bitumens” in its name, it is sometimes applied to penetration grade bitumen carried hot. That is wrong. Penetration grade bitumen does not meet the Class 3 flash point criterion, and the correct entry for it when carried at or above 100°C is UN 3257. Using UN 1999 for hot penetration grade product misdeclares the consignment and, more practically, puts the wrong markings on the tank.
Three rules of thumb, each of which should be confirmed against the product’s own safety data sheet:
| Product | Typical classification | Driver |
|---|---|---|
| Penetration grade bitumen carried hot | UN 3257, Class 9, Packing Group III | Carried at or above 100°C and below its flash point |
| Cutback bitumen | UN 1999, Class 3, Packing Group II or III | Solvent content lowers the flash point to 60°C or below |
| Bitumen emulsion | Frequently not regulated for transport | Water continuous phase, handled at ambient temperature |
Polymer modified binders follow the hot bitumen route in most cases, because modification changes rheology rather than flash point. We cover the handling implications of PMBs separately in storing and handling polymer modified bitumen.
One point worth stating plainly. Classification is a shipper responsibility, determined from the actual product’s safety data sheet and the conditions of carriage. A supplier can tell you how a product is normally classified, but the consignor is accountable for getting it right on a specific consignment.
What Class 9 requires in practice
The Class 9 label and the elevated temperature mark
UN 3257 consignments carry two separate markings, and operators new to the entry frequently miss the second one.
The first is the Class 9 label (Model No. 9), a white square set at 45 degrees with seven vertical black stripes across the upper half and the figure 9 underlined in the lower corner.
The second is the elevated temperature mark, set out in ADR 5.3.3. It is a red equilateral triangle containing a thermometer symbol, with a minimum side length of 250 mm, reducible to 100 mm on tank containers and portable tanks of 3,000 litres or less where surface area does not allow the full size.
The mark is required where a substance is carried in a liquid state at or above 100°C, or in a solid state at or above 240°C. It must appear on both sides and at the rear of a vehicle, or on both sides and at each end of a container, tank container or portable tank. It is a separate requirement from the Class 9 label, not an alternative to it.
A tank carrying hot bitumen by road in Europe therefore displays orange plates showing hazard identification number 99 over UN number 3257, the Class 9 label, and the elevated temperature mark.
Documentation
A UN 3257 movement requires a dangerous goods transport document identifying the consignment in the standard sequence: UN number, proper shipping name, class, packing group. For hot bitumen this reads as UN 3257, ELEVATED TEMPERATURE LIQUID, N.O.S., 9, III, followed by the technical name of the substance in brackets.
Movements by sea additionally require a Dangerous Goods Declaration and, for containerised cargo, a Container Packing Certificate.
Under ADR 1.8.3, undertakings involved in the carriage of dangerous goods by road must appoint a Dangerous Goods Safety Adviser. The scope is wider than many operators assume. It covers carriers, packers, fillers, loaders and unloaders, and since 1 January 2023 it expressly covers consigning as well. Exemption is not simply a matter of staying under a tonnage figure: it applies where quantities fall within the small load, limited quantity or excepted quantity provisions, or where the carriage of dangerous goods is not the undertaking’s main or secondary activity. A business shipping hot bitumen as a core part of what it does will not meet the second test.
How the rules change by transport mode
The UN number stays constant. The regulatory framework around it does not.
| Mode | Framework | Issuing body |
|---|---|---|
| Road | ADR | UNECE |
| Rail | RID | OTIF |
| Sea | IMDG Code | IMO |
| Inland waterway | ADN | UNECE, with the CCNR |
| Air | ICAO Technical Instructions and IATA Dangerous Goods Regulations | ICAO |
Each sets its own requirements for tank construction, marking, segregation and documentation. A tank approved for road carriage under ADR is not automatically acceptable for a sea leg under the IMDG Code, which is the single most common compliance gap on multimodal bitumen movements.
Air is the exception that removes the question entirely. UN 3257 is forbidden on both passenger and cargo aircraft, and there is no air packing instruction for it. The same bitumen shipped cold is not a dangerous good at all and is unrestricted, which is a useful illustration of how much of this framework is about temperature rather than the material itself.
Our guide to regulations for bitumen transport goes through the mode-by-mode requirements in more depth.
What this means for equipment
Classification determines the tank, not just the paperwork. Two specifications matter.
ADR and RID tank codes. Road and rail tanks carry a four-character code describing what the tank is approved to carry. ADR Table A specifies tank code LGAV for UN 3257, and that is the code TEC’s ADR/RID Bitutainer™ is approved to. It reads as follows:
| Character | Meaning |
|---|---|
| L | Tank for substances in the liquid state, including solids handed over for carriage in the molten state |
| G | Minimum calculation pressure according to the general requirements of ADR 6.8.2.1.14 |
| A | Tank with bottom filling or bottom discharge openings fitted with two mutually independent closures in series |
| V | Tank with a venting system to ADR 6.8.2.2.6 but no flame trap, or a tank that is not explosion pressure proof |
The V is worth understanding rather than skimming. It does not mean the tank is loosely closed. It means the venting system is not fitted with a flame trap, which is acceptable for UN 3257 precisely because the substance is carried below its flash point and so is not generating a flammable atmosphere in the ullage space. A product that did generate one would need an F coded tank instead. This is the clearest illustration of why classification drives equipment: the same vessel geometry with different venting hardware serves a different UN entry.
IMDG portable tank instructions. Sea movements use a T-code rather than a tank code. The IMDG Bitutainer™ holds a T3 rated internal pressure vessel, placing it within the portable tank instruction framework used across containerised liquid shipping. Readers already familiar with T-codes from ISO tank specification will recognise the same system applied to a purpose-built bitumen unit.
A useful detail for anyone planning multimodal routes: the IMDG Bitutainer™ carries ADR and RID approval in addition to CSC, TIR, ISO 1496-3, US DOT and Transport Canada. It is specified for sea but is not restricted to it.
Not every bitumen movement needs a dangerous goods approved tank. Where bitumen is shipped cold and reheated on arrival, the consignment may fall outside the elevated temperature entry entirely. That is the operating model the Shipper Bitutainer™ is built around, and it changes the regulatory position of the movement rather than simply the cost of it.
The full range is set out on our bitumen containers page.
Frequently asked questions
What are Class 9 dangerous goods?
Class 9 dangerous goods are substances and articles that pose a hazard during transport but do not meet the criteria for any of the other eight classes. Examples include lithium batteries, dry ice, asbestos, environmentally hazardous substances and elevated temperature substances such as hot bitumen.
What is UN 3257?
UN 3257 is the UN number for elevated temperature liquid, not otherwise specified, at or above 100°C and below its flash point. It is a Class 9 dangerous good in Packing Group III with classification code M9, and it is the entry used for hot bitumen.
What is the UN number for bitumen?
It depends on the product and how it is carried. Penetration grade bitumen transported at or above 100°C is UN 3257 under Class 9. Cutback bitumen, which contains solvent and has a flash point of 60°C or below, is UN 1999 under Class 3. Bitumen emulsions are frequently not regulated for transport. Always confirm against the product’s safety data sheet.
Is hot bitumen a flammable liquid?
No. At normal handling temperatures of 140°C to 180°C, penetration grade bitumen is well below its flash point. EN 12591 paving grade bitumens specify a minimum flash point of around 230°C and actual values are often higher. Hot bitumen is classified under Class 9 because of its temperature, not its flammability. Cutback grades containing solvent are a different case and are classified as flammable liquids.
What markings are required for UN 3257?
Both the Class 9 label and the elevated temperature mark. The elevated temperature mark is a red equilateral triangle containing a thermometer symbol, minimum 250 mm per side. Under ADR 5.3.3 it is required on both sides and the rear of a vehicle, or on both sides and each end of a container or tank container, in addition to orange plates showing hazard identification number 99 over UN number 3257.
Can UN 3257 be shipped by air?
No. Elevated temperature liquids under UN 3257 are forbidden on both passenger and cargo aircraft. The same material shipped at ambient temperature, where it is not a dangerous good at all, is unrestricted.
Does Class 9 apply to storage as well as transport?
The UN classification system governs transport only. Static storage falls under separate national health, safety and environmental legislation. In the UK the principal regimes include DSEAR for fire and explosion risk, COSHH, the Health and Safety at Work etc. Act, and COMAH where an establishment holds qualifying substances above the lower or upper tier thresholds. A tank compliant for transport is not automatically compliant as a storage installation.
Getting the classification right
Most of the cost of getting dangerous goods classification wrong is not the fine. It is a consignment held at a port, a vehicle turned back at a border, or an insurance position that does not hold when it is tested.
The three questions worth asking before any bitumen movement are straightforward. What is the actual product and what does its safety data sheet say. What temperature will it be at when it is offered for carriage. Which modes will it travel by, and is the tank approved for all of them.
TEC designs and builds bitumen containers for operators moving product across all three of those variables. If you are working through a route and want to discuss the equipment side, get in touch with the team.