How to correctly seal UN‑approved packaging – a practical guide from Emballator

When hazardous goods are transported, the packaging must perform exactly as intended. Correct sealing is essential for safety and for meeting international requirements. To help you feel confident when working with our UN‑approved metal packaging, we’ve put together a straightforward guide based on our own product range.

Understanding the UN certificate

A UN certificate confirms that the complete packaging — the container, the lid and all components used together — meets the UN requirements for dangerous goods. This means each part must be used in the approved combination. Even if components are manufactured to specification, they must be assembled exactly as tested for the certificate to remain valid.

Proper sealing after filling is therefore critical. The following sections summarise what to keep in mind to ensure your packaging meets the requirements in ADR‑S part 6.1.1.5.

Cans with press lids

Our UN cans with press‑down lids are available in Ø 99, 105 and 153 mm. They use TT‑type (Triple Tight) lids and rings. Glue is applied inside the ring and must make direct contact with the lid during sealing. Together with friction, this ensures the lid stays securely in place — even if the packaging is exposed to impact, such as a fall.

To achieve a proper seal:

• Use a minimum force of 2200 N for Ø 99 and Ø 105
• Use a minimum force of 3000 N for Ø 153
• After sealing, the lid should sit level with the seam edge of the can
• If needed, a special pressure plate can be used to press the lid slightly below edge level.

Press lid with ring latch (UN)

This design consists of a pail, a UN press lid and a UN ring latch with lock pin. Together, they ensure the lid remains secure if the packaging is exposed to internal pressure or external force.

Sealing process:

1. Assemble the pail and the UN press lid using a standard lid‑press with a plate and air cylinder.Recommended pressing force: approximately 2000 N
2. Close the UN ring latch around the lid and the pail’s profile.
3. Make sure the ring latch fully encloses both the lid and the pail edge.
4. Insert the correct locking pin so the ring latch cannot be opened unintentionally.

Pails with lug lids

Our UN pails with lug lids are available in Ø 180 and 285 mm.

The lid includes metal lugs that must be pressed under the top rolled edge of the pail to hold the lid firmly in place.

Important points:

• A dedicated sealing tool is required.
• Ensure each lug is pressed correctly under the rolled edge.
• Perform a visual check — or measure the roll height — to confirm proper sealing.

If sealing quality decreases, the tool may be worn or damaged. It may also indicate insufficient air pressure, meaning the tool cannot reach the required force.

EasyOpen UN

The EasyOpen UN system consists of a pail and a lid with a plastic safety ring. The ring ensures the lid stays in place when exposed to internal pressure or external impact. The lid is assembled using a conventional lid‑press with plate and air cylinder.

Key guidelines:

Place the lid centred on the pail.

Required sealing force:

• Approx. 4000 N for EasyOpen 180 UN
• Approx. 6000 N for EasyOpen 285 UN
• For easy assembly, the lid should be at least 20°C.
• If stored cold, move lids to room temperature 24 hours before use.