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1. Why Packing Matters — Common Reasons Shipments Get Returned
In dangerous goods transport, poor packing isn't just a matter of damage. It leads to airline rejection, seizure at destination customs, or the entire shipment being returned. Here are the most common causes.
🚫 Common reasons shipments are returned for poor packing:
① Not using a UN-certified container (using a plain cardboard box instead)
② No UN number or warning label on the outer packaging
③ Insufficient insulation or waterproofing on the inner packaging
④ Lithium batteries packed above 30% state of charge
⑤ Mixing dangerous goods with general cargo in the same package
① Not using a UN-certified container (using a plain cardboard box instead)
② No UN number or warning label on the outer packaging
③ Insufficient insulation or waterproofing on the inner packaging
④ Lithium batteries packed above 30% state of charge
⑤ Mixing dangerous goods with general cargo in the same package
Packing standards vary by hazard class and packing group (PG). Always confirm the packing requirements for your specific item before shipping.
2. What Is a UN-Certified Container? — Types and How to Read the Codes
A UN-certified container is packaging that meets UN standards for safely containing dangerous goods. The UN certification mark and code are printed on the outer packaging so it can be verified.
| Container Code | Container Type | Material | Main Use |
|---|---|---|---|
| 1A1 | Closed-head drum | Steel | Liquid dangerous goods (Class 3, 8, etc.) |
| 1A2 | Open-head drum | Steel | Solid dangerous goods |
| 1H1 | Closed-head drum | Plastic (HDPE) | Liquid chemicals, corrosive substances |
| 3A1 | Closed-head can | Steel | Small quantities of flammable liquid |
| 4G | Fiberboard box | Corrugated board | Solid dangerous goods, small shipments |
| 4GV | Fiberboard box (special) | Corrugated board | Batteries, specialty dangerous goods |
| 6HA1 | Composite packaging (inner bottle + outer box) | Glass + corrugated board | Small quantities of liquid dangerous goods |
💡 How to read a UN code: example
4G = fiberboard box / X = highest packing group rating (approved for PG I) / 5 = maximum gross weight (kg) / S = for solids / 26 = year of manufacture / KR = country / AA1234 = manufacturer certification number
4G/X5/S/26/KR/AA12344G = fiberboard box / X = highest packing group rating (approved for PG I) / 5 = maximum gross weight (kg) / S = for solids / 26 = year of manufacture / KR = country / AA1234 = manufacturer certification number
3. Packing Group (PG I/II/III) Classification
Every dangerous good is assigned a Packing Group (PG) based on hazard level. The higher the PG, the stricter the packing requirements.
Highest hazard
PG I
High-hazard items. The strictest packing requirements apply. UN-certified X-grade containers required. Often requires cargo-only aircraft (CAO).
X-grade container
Medium hazard
PG II
Medium-hazard items. UN-certified Y-grade or higher containers used. The grade most dangerous goods fall under.
Y-grade or higher
Lower hazard
PG III
Low-hazard items. UN-certified Z-grade or higher containers are acceptable. Many items in this group qualify for the Limited Quantity (LQ) exemption.
Z-grade or higher
| PG | Hazard Level | Container Grade | Air Loading | Example Items |
|---|---|---|---|---|
| PG I | High | X grade | Often CAO only | Concentrated sulfuric acid, mercury, etc. |
| PG II | Medium | Y or higher | Both CAO and PAX possible (item-dependent) | Lithium batteries (per PI), flammable liquids, etc. |
| PG III | Low | Z or higher | Often PAX-eligible | Small-quantity paint, household chemical products, etc. |
4. Inner and Outer Packing Requirements — Air Transport Standards
Dangerous goods packing is composed of two layers: inner packaging (primary packaging) and outer packaging. Each layer has its own requirements.
01
Inner packaging — the container in direct contact
This is the first container in direct contact with the dangerous good. Chemical resistance of the material and leak-proof sealing are key.
Liquids: fill to 95% of container volume or below (headspace for thermal expansion)
Batteries: discharge to 30% SOC or below + individual insulation
Double-sealed caps/stoppers to prevent leaks — accounting for low cabin pressure
Wrap the inner container in absorbent material (vermiculite, absorbent paper, etc.)
02
Outer packaging — UN-certified containers
This is the final outer container holding the inner packaging. Depending on the PG, you must use a UN-certified X/Y/Z grade container or higher, as specified.
Confirm the UN certification mark and code are printed on the outer packaging
Fill empty space with cushioning material (bubble wrap, foam, etc.) to prevent shifting
Seal and reinforce joints with tape
03
No mixed packing of incompatible dangerous goods
Dangerous goods that could react with each other cannot go in the same outer package. Mixing dangerous goods with general cargo may also be restricted.
Oxidizers (Class 5) and flammable substances (Class 3) cannot be mixed
Avoid packing general cargo like documents or clothing in the same box
5. Dangerous Goods Label and Marking Requirements
The following labels and markings must be affixed to the outer packaging. Airline acceptance staff check these items on-site.
| Label/Marking Type | Content | Size | Required? |
|---|---|---|---|
| Hazard class label | Class number and pictogram (e.g. Class 3 flame) | 100×100mm minimum | Required |
| UN number marking | "UN" + 4-digit number (e.g. UN3480) | 12mm+ lettering | Required |
| Orientation arrow marking | "This side up" marking for liquid dangerous goods | On both sides | Required for liquids |
| Cargo Aircraft Only label | Cargo-only aircraft marking (red background) | Standard size | Required for CAO items |
| Lithium battery mark | Battery pictogram + UN number + Wh | 120×110mm | Required for battery items |
| Total weight marking | Total package weight (kg) | Legible size | Required |
| LQ diamond mark | Limited Quantity exemption marking | 100×100mm | Required when LQ applies |
⚠️ Damaged or missing labels cause shipments to be returned in transit. Use waterproof labels, and take care not to cover them with tape.
6. Limited Quantity Packing Exemption Conditions
A Limited Quantity (LQ) exemption applies relaxed packing and documentation rules once a dangerous good's inner packaging volume falls under a certain threshold. All conditions must be met precisely to qualify.
①
Meet the inner packaging volume threshold
IATA sets a maximum volume per inner package for each item under the LQ rules. Example: for Class 3 flammable liquid, PG II — inner packaging must be 1L or below.
②
Total weight of 30kg or below per package
If the total weight per outer package exceeds 30kg, it no longer qualifies for LQ treatment.
③
Attach the LQ diamond mark to the outer packaging
A white background, black-bordered diamond mark must be affixed to the outer packaging. Minimum size is 100×100mm.
④
Confirm items ineligible for LQ
Not every dangerous good qualifies for LQ treatment. Some items, such as Class 1 (explosives) and Class 7 (radioactive materials), cannot use the LQ exemption.
✅ Benefits of LQ eligibility: DGD (Dangerous Goods Declaration) preparation exempted / PAX loading possible (not just CAO) in many cases / simplified import declaration at some destination countries. Note that the MSDS and general documents (Invoice, Packing List) are still required.
7. Tosome Logis Dangerous Goods Packing Service
If the packing standards feel too complex to handle yourself, leave it to Tosome Logis. We review your MSDS, confirm the packing standard, and handle everything — UN-certified containers, inner packaging processing, labels and markings — in one package.
Tosome Logis Dangerous Goods Packing Service
📦Packing standard confirmation — PG and UN container type auto-determined from your MSDS
🧪Inner packing processing — liquid sealing, battery SOC discharge and insulation, absorbent packing
🏷️UN-certified outer packaging — sourcing the correct certified container for the PG
🔖Full label and marking application — class labels, UN number, orientation markings, battery marks
✅Free LQ eligibility check — when applicable, simplified documentation saves cost
⚡Same-day intake, same-day dispatch — shipped immediately once packing is complete
🔬Small samples welcome (10g) — we handle small shipments most competitors refuse
8. Frequently Asked Questions About Dangerous Goods Packing
Items in PG I/II must use UN-certified containers. Some PG III items and shipments meeting the Limited Quantity (LQ) exemption can use sturdy outer packaging without UN certification in some cases. Exact requirements vary by item, so confirm with a specialist forwarder.
The Packing Group (PG) is classified by hazard level: PG I (high hazard), PG II (medium), and PG III (low hazard). The higher the PG, the stricter the packing requirements and the higher the required UN container grade. This can be confirmed in Section 14 of the MSDS or in the IATA DGR.
Dangerous goods labels can be purchased online or from packing supply specialists. If Tosome Logis handles your packing, label application is included. Label size (minimum 100×100mm) and color standards must be followed.
Meeting LQ criteria exempts the DGD requirement and expands eligibility for passenger aircraft (PAX) loading. However, the outer packaging must carry the LQ diamond mark, and both the inner packaging volume and per-package weight thresholds must be met.
Tosome Logis handles the entire dangerous goods packing process — UN-certified container selection, inner packing processing, and label/marking application. Just send us your MSDS and we'll confirm the packing standard and handle dispatch. Contact us via KakaoTalk or at 0507-1399-4075.
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