- A Dangerous Goods Packaging Certificate (危包证 in Chinese) is official proof that packaging has passed UN performance tests for a specific hazard class and packing group. In China, it is a mandatory export document -- without it, customs will not release DG cargo.
- Every UN-certified package carries a specification marking that encodes the packaging type, performance level, test parameters, country, and manufacturer. You can read this marking to verify the packaging matches your cargo.
- Using the wrong packaging -- e.g., a Packing Group II drum for a Packing Group I substance -- is a compliance violation that carriers and customs both check for. The consequences range from shipment rejection to regulatory penalties.
You cannot ship dangerous goods in whatever box you have lying around. The packaging must pass performance tests -- drop tests, stack tests, hydraulic pressure tests, leakproofness tests. Those tests are calibrated to the hazard. Packing Group I (high danger) requires more severe testing than Packing Group III (low danger). The certificate proves the packaging passed.
In China, this is the 危包证 (full name: 出入境危险货物运输包装使用鉴定结果单). It is issued by China Customs (formerly the Entry-Exit Inspection and Quarantine authorities) after the packaging has been tested and found suitable for the specific dangerous goods it will contain. Exporters of chemicals and batteries from China deal with this document on every shipment. Without it, the cargo does not leave the port.
How to Read a UN Mark
Every UN-certified package has a permanent marking stamped or printed on it. The format follows a strict sequence. Once you know the code, you can verify packaging in seconds. Here is how to break it down:
| Position | Element | Meaning |
|---|---|---|
| 1 | UN symbol | The stylized "UN" in a circle (or embossed "UN" on metal) |
| 2 | Packaging code | Type + material + category (see below) |
| 3 | Performance letter | X = PG I, II, III; Y = PG II, III; Z = PG III only |
| 4 | Mass or SG | Max gross mass in kg (solids) or max specific gravity (liquids) |
| 5 | S or pressure | "S" for solids; hydrostatic test pressure in kPa for liquids |
| 6 | Year | Last two digits of manufacture year (e.g., "25" = 2025) |
| 7 | Country | Authorizing state (e.g., USA, CN, GB, D) |
| 8 | Manufacturer | Name, symbol, or certificate number of manufacturer |
The packaging code is the most information-dense element. It uses three characters:
- First digit -- type: 1 = drum, 3 = jerrican, 4 = box, 5 = bag, 6 = composite packaging
- Capital letter -- material: A = steel, B = aluminum, D = plywood, G = fibreboard, H = plastic, L = textile, M = paper, N = metal (not steel/aluminum)
- Third digit -- category: 1 = closed head (non-removable top), 2 = open head (removable top)
Real Examples
Steel drum for flammable liquid:
UN 1A1/X1.6/250/25/USA/M4567
Closed-head steel drum (1A1), tested for all packing groups (X), maximum specific gravity 1.6, hydrostatic test pressure 250 kPa, manufactured 2025 in the United States.
Fibreboard box for limited quantities:
UN 4G/Y30/S/24/CN/C23008
Fibreboard box (4G), tested for Packing Groups II and III (Y), maximum gross mass 30 kg, for solids (S), manufactured 2024 in China.
Plastic drum for corrosive liquid:
UN 1H1/Y1.9/100/25/GB/ABC789
Closed-head plastic drum (1H1), tested for PG II and III (Y), maximum specific gravity 1.9, test pressure 100 kPa, manufactured 2025 in the United Kingdom.
The Testing That Backs the Mark
The UN performance tests are not gentle. Drop test heights scale by packing group: 1.8 metres for PG I (X), 1.2 metres for PG II (Y), 0.8 metres for PG III (Z). Drops hit the package's weakest points: edges, corners, faces. After the drop: no leaks, inner packaging intact.
The stack test applies a load equivalent to packages stacked at least 3 metres high. Duration: 24 hours minimum, or 28 days for plastic packaging at controlled temperature. The hydrostatic pressure test (for liquid packaging) applies internal water pressure -- typically up to 250 kPa held for 5 minutes. The leakproofness test submerges the package under air pressure for 5 minutes. No bubbles permitted.
The test report goes to the competent authority, which issues the packaging certificate. The certificate and the marking together form the compliance evidence. Both must be present. Both must be consistent. Both must match the cargo.
The Trap: Packing Group Mismatches
The most common packaging compliance error is simple: using the wrong performance level. A shipper has a UN 4G/Y30/S box -- certified for Packing Groups II and III. They fill it with a Packing Group I substance. The carrier or customs checks, sees the Y where there should be an X, and rejects the shipment.
This happens because people remember the packaging code (4G) but forget the performance letter (Y vs X). A fibreboard box is a fibreboard box -- until you realize the Y-rated box cannot legally carry your PG I cargo. Always verify the performance letter against the packing group in the Dangerous Goods List for your UN Number.
Another trap: reused packaging. UN-certified drums can be reconditioned and retested, but the marking must reflect the retest. A 2019 drum that was retested in 2024 should carry updated markings. If the markings are worn, illegible, or inconsistent with the certificate, the packaging is non-compliant.
Frequently Asked Questions
How do I know if my dangerous goods packaging has the correct UN certification?
Check the UN specification marking on the outer surface. It must be permanent, legible, and follow the sequence: UN symbol, packaging code, performance letter (X/Y/Z), mass or specific gravity, S or test pressure, year, country, manufacturer. If the marking is missing, illegible, or the performance letter is lower than required for your substance's packing group, the packaging is not compliant. In China, also verify that the 危包证 certificate matches the marking and the goods.
What happens if I ship dangerous goods without a valid packaging certificate?
Carrier refusal is the first line. If the carrier accepts without checking, customs and port state control are the second line -- they can seize goods and impose fines. If packaging fails and causes damage, the consequences escalate to criminal liability for knowing violations and civil liability for all resulting damage. Insurance policies typically exclude coverage for losses caused by non-compliant packaging. In China, the 危包证 is a hard requirement for DG export -- without it, customs will not process the declaration.
Related Terms
- IMDG Code -- The primary regulatory framework governing dangerous goods transport by sea, incorporating the UN packaging certification system.
- IATA DGR -- The IATA Dangerous Goods Regulations for air transport, applying UN packaging standards to air cargo.
- UN3536 -- Lithium batteries installed in cargo transport units; these have specialized packaging and certification requirements distinct from conventional DG packaging.
- MSDS -- The document that identifies the hazardous properties of a substance and the required packing group, which determines the certification level needed for the packaging.
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