How To Apply UN Number Marking On Packages: Placement, Durability, And Examples

UN Number Marking A package marking displaying the applicable four-digit UN identification number for a dangerous good. Applying it correctly requires matching the UN number to the material, placing it where it is legible, and using durable materials compatible with the transport mode.

Correct application of a UN Number Marking reduces rejections, inspection holds, and safety risks. The following sections provide a practical step-by-step approach, layout guidance, and common pitfalls to avoid when marking packages for hazardous materials shipments.

Step-By-Step Marking Process

Start by identifying the proper shipping name and UN number from the Hazardous Materials Table or applicable modal code. Confirm packing group, any subsidiary hazards, and whether a limited quantity, excepted quantity, or ORM-D (where applicable) provision applies. Apply the UN number that corresponds to the final shipped form (e.g., solution concentration or mixture listing) — not an ingredient unless the mixture is regulated by that ingredient's UN number.

Placement And Legibility Guidance

• Outside placement: Mark the UN number on the outside of the package or overpack so it is clearly visible without moving the load.
• Contrast: Use contrasting colors or a label with a white/dark background so the alphanumeric code is readable at a glance.
• Size: Ensure lettering is large enough to be read from a normal working distance; follow modal specs when applicable.

Durability And Materials

Use materials that withstand the expected handling and environmental conditions. Permanent printed labels, weatherproof tags, or direct printing on the package are preferred over temporary tape or handwritten marks that can smear. For ocean or air shipments where exposure to moisture or abrasion is likely, select labels and inks rated for those conditions.

Special Cases: Overpacks, Inner Packages, And Repacking

If items are packed in inner packages within an outer package, the outer package (or overpack) must display the UN number unless each small package is required to be marked. When repacking occurs at a consolidation facility, the repacker becomes responsible for ensuring the UN number and other required markings are present and match the shipping papers.

Common Mistakes

• Mismatched information: UN number does not match the proper shipping name or SDS — this causes immediate noncompliance and safety risk.
• Illegible marks: Faded ink, poor contrast, or small fonts that cannot be read without close inspection.
• Temporary application: Handwritten numbers on tape that rub off in handling.

Practical Example

A 3PL consolidates multiple small packages containing aerosols. Each inner box shows the flammable gas label and the UN number UN1950 on the overpack. The consolidation facility prints a durable, weatherproof label marked "UN1950" and affixes it to two opposing sides of the pallet overpack. Shipping papers and the air waybill reference UN1950; the carrier confirms marking during pickup.

Tips For Implementation

• Standardize Templates: Use pre-printed label templates for each UN number you commonly ship to ensure consistency.
• Quality Control: Implement a final check that compares UN number, shipping name, and SDS before tender to carrier.
• Train Staff: Train packers and check-in staff on identifying the correct UN number for mixtures and on how to apply durable markings.
• Review Modal Rules: Check IATA or IMDG requirements for specific size and placement rules when shipping by air or sea to avoid modal rework.

In short, the UN Number Marking must be accurate, legible, and durable; match the shipping papers; and be placed so responders and carriers can readily identify the dangerous good. Use standardized labels, durable materials, and cross-checks to keep shipments moving and compliant across modes.