UN 1H2 Certification for HDPE Pails

Every UN-marked pail carries a string of characters that looks like a license plate. That string is not marketing — it is a compact encoding of what the pail is, how it was tested, and what it is certified to carry. This page decodes the format.

The full format

A UN packaging marking looks like this:

1H2/Y27/S/[year]/USA/[registration]

Each segment carries specific information:

  • 1 — Container type (1 = single packaging, no inner receptacles)
  • H2 — Material and design (H = plastic; 2 = non-removable head, open-head configuration)
  • Y — Performance level (X = Packing Group I, Y = Packing Group II, Z = Packing Group III)
  • 27 — Rated gross mass in kilograms (for solids) OR density in kg/L (for liquids)
  • S — Contents type (S = solid; a hydrostatic pressure value here indicates liquid rating)
  • year — Year of manufacture
  • USA — Country of certification
  • registration — Manufacturer's UN registration code

Read that way, 1H2/Y27/S/2024/USA/M#### decodes as: single plastic pail, non-removable head, tested to Packing Group II performance for solid contents up to 27 kg gross mass, manufactured in 2024 in the United States by the registered manufacturer whose UN code follows the "M".

Why "1H2" is the pail category

The "1H2" prefix specifically identifies open-head plastic pails. Other codes exist for other container types — 1H1 is closed-head plastic (the drum-style with a small bung opening, not a pail), 1A2 is open-head steel, 3H2 is a plastic jerrican with non-removable head. When someone says "1H2 certification," they mean the certification specifically for open-head plastic pails like the ones we sell.

What Y vs X vs Z means

The performance level letter is often what compliance teams focus on:

  • X — Tested to Packing Group I standards. Suitable for PG I, II, and III materials (highest hazard tier).
  • Y — Tested to Packing Group II standards. Suitable for PG II and PG III materials.
  • Z — Tested to Packing Group III standards. Suitable only for PG III materials (lowest hazard tier).

A "Y" pail is not "lower quality" than an "X" pail — it means the manufacturer tested and certified it to Packing Group II performance, which is what the market needs for most solid hazmats. Testing to PG I performance is more expensive and unnecessary if you are never shipping PG I materials.

Solid rating vs liquid rating

The character after the gross mass number tells you what contents the pail was tested with:

  • S — Tested with solid contents. Not certified for liquids.
  • A hydrostatic pressure value (typically 30 kPa or higher) — Tested with liquid contents at that pressure. Certified for liquids of appropriate density and Packing Group.

This distinction matters because the test protocols are different. Solid testing verifies structural integrity against drop and stack loads. Liquid testing adds hydrostatic pressure to verify seal integrity under fluid pressure. A pail marked with "S" was not subjected to liquid testing, so it does not carry a liquid claim.

Our M2 pail is 1H2/Y27/S — solid-rated. Our M4 pail carries three liquid-rated markings (1H2/Y1.5/30, 1H2/X40/S, 1H2/Y40/S) depending on configuration.

What the marking does NOT tell you

The UN marking is a structural and packaging-performance claim. It does not tell you:

  • Whether the pail's material is chemically compatible with your specific contents (check the chemical compatibility guide)
  • Whether the pail satisfies IATA air transport requirements (it does not, for liquids at this size)
  • Whether the pail satisfies any specific customer or regulatory approval beyond UN certification itself
  • Anything about the pail's food-contact suitability, resin type, or manufacturing origin beyond what the country code implies

These require separate certifications, letters, or documentation.

When the marking is invalid

A UN marking on the pail body only certifies the closed container when the closure has been correctly installed per the manufacturer's published closure instructions. If the lid is not fully seated, if it has been reused after removal, or if the pail has been damaged, the UN certification no longer applies to that specific container even though the marking is still embossed on it.

This is not a paperwork technicality — it is the reason UN certification exists in the first place. The marking backs a specific tested condition. If your container is not in that condition, the marking's guarantee does not apply.

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