In international shipping, a packing group (PG) determines the level of danger a substance poses and the type of packaging required to ensure safe transport. Selecting the wrong packing group can result in shipment delays, fines, or even accidents. Read on to learn how to find the correct hazmat packing group for smooth delivery.
Table of Contents:
What are hazardous materials in air shipping?
A packing group is a classification system used to indicate the level of hazard a substance presents during transportation. Hazardous materials are categorized into Packing Group I, II, or III, with:
- Packing Group I (High Danger): Substances with a high level of risk. Requires the most robust packaging.
- Packing Group II (Medium Danger): Moderate risk materials. Packaging must meet specific regulatory requirements.
- Packing Group III (Low Danger): Low-risk materials. Standard packaging is acceptable.
Packing groups of hazardous materials helps logistics professionals choose the correct container, cushioning, and labeling, minimizing accidents during transit.
How to determine your packing group
Determining the correct packing group requires knowing your cargo’s UN number, chemical properties, and regulatory classification. Follow these steps:
- Identify the UN Number: Each hazardous material has a unique UN number used worldwide.
- Check the Material Safety Data Sheet (MSDS): MSDS provides critical info about flammability, reactivity, and toxicity.
Once you identify the UN number and material classification, the packing group assignment adheres to international standards. DOT, IATA, and IMDG codes specify the packaging requirements for each group.
Here’s a breakdown by hazard class:
Class 3 – Flammable Liquids
| PG | Flash Point | Boiling Point |
|---|---|---|
| I | — | ≤ 95°F |
| II | ≤ 73°F | > 95°F |
| III | ≥ 73°F but ≤ 141°F | > 95°F |
Class 4 – Flammable Solids
Division 4.1 – Flammable Solids
| PG | Substance | Parameters |
|---|---|---|
| II | Readily combustible solids | Burning time < 45 s; flame passes wetted zone |
| II | Powders of metal or alloys | Reaction spreads over whole sample length ≤ 5 min |
| III | Readily combustible solids | Burning time < 45 s; wetted zone stops flame propagation ≥ 4 min |
| III | Powders of metal | Reaction spreads over whole sample in > 5 min but < 10 min |
Division 4.2 – Spontaneously Combustible
- PG I: Pyrophoric solids and liquids
- PG II: Self-heating materials, positive result with 25 mm cube at 284°F
- PG III: Self-heating materials, positive result with 100 mm cube at 284°F
Division 4.3 – Dangerous When Wet
- PG I: Vigorous reaction with water at ambient temperatures; ≥ 10 L flammable gas/kg material
- PG II: Readily reacts with water; produces 20 L flammable gas/kg, but does not meet PG I
- PG III: Reacts slowly with water at ambient temperatures
Class 5 – Oxidizers
Division 5.1 – Oxidizing Substances
- PG I: Burning time faster than a 3:2 potassium bromate + cellulose mixture
- PG II: Burning time faster than 2:3 potassium bromate + cellulose mixture
- PG III: Burning time faster than 3:7 potassium bromate + cellulose mixture
Class 6 – Toxic Substances
| Packing Group | Oral Toxicity (LD50, mg/kg) | Dermal Toxicity (mg/kg) | Inhalation Toxicity (mg/L) |
|---|---|---|---|
| I | < 5 | < 50 | < 0.2 |
| II | 5–50 | 50–200 | 0.2–2 |
| III | 50–300 | 200–1,000 | 2–4 |
Class 8 – Corrosive Substances
- PG I: Destroys full thickness of intact skin tissue within 60 minutes after ≤ 3 min exposure.
- PG II: Destroys full skin thickness within 14 days after ≥ 3 min but < 60 min exposure.
- PG III: Corrodes steel or aluminum at a rate > ¼ inch per year.
Class 9 – Miscellaneous Dangerous Goods
Lithium-ion batteries fall under Class 9 because of their fire risk.
- Small consumer batteries usually belong to Packing Group III.
- Large industrial batteries often require Packing Group II or higher.
- Always follow IATA, DOT, and IMDG guidelines.
For other Class 9 materials, check the Hazardous Materials Table or consult a qualified hazmat specialist.
Key takeaway
Each packing group assignment depends on measurable parameters such as flash point, reaction time, burning time, or toxicity levels. Your inspection partner should carefully test and document these criteria to prevent misclassification, delays, or compliance issues. At ASLG, we review test reports and recommend enhanced packaging to ensure secure loading and safe shipping.
How Airsupply supports your hazardous materials shipping
Proper packing not only ensures regulatory compliance but also guarantees the safety and smooth delivery of your cargo across borders.
At ASLG, we apply our extensive expertise in hazardous materials shipping to provide fast, seamless customs clearance and international shipment services.
Every month, we handle over 90 metric tons of battery shipments and regularly manage full-container shipments of e-cigarettes. We guide you through every step and ensure your cargo reaches its destination safely and on time.
