• Some dangerous goods are further categorized into packing groups, which indicates the level of danger (high to low) that the dangerous goods present.

Some dangerous goods are further subdivided into packing groups. The packing group indicates the degree of danger presented by the dangerous goods.

• Packing Group I — high danger
• Packing Group II — medium danger
• Packing Group III — low danger

Packing groups have been developed for dangerous goods in Class 3, Class 4, Division 5.1, Division 6.1 and Class 8 materials. Some hazardous materials are assigned more than one packing group. Because packing groups impact the type of packaging that can be used, it is critical that each material is assigned to the correct one. The criteria for determining packing groups are included in the IMDG Code as follows:

• Chapter 2.3 — Class 3 (flammable liquid) materials
• Chapter 2.4 — Class 4 (flammable solid) materials
• Chapter 2.5 — Division 5.1 (oxidizing) materials
• Chapter 2.6 — Division 6.1 (poisonous) materials
• Chapter 2.8 — Class 8 (corrosive) materials

Some substances in Class 9, liquids in Division 5.1, and waste in Division 6.2 have been assigned packing groups according to the Dangerous Goods List in IMDG Code Chapter 3.2. Requirements for a specific packaging performance level can be found in the applicable packing instruction.

Marine pollutants

The IMDG Code requires shippers to also classify dangerous goods as a marine pollutant if:

• A “P” is listed in column 4 of the Dangerous Goods List,
• A “P” is listed in a column titled “MP” in the Index, or
• It meets the requirements of a marine pollutant listed in Chapter 2.9.3.

UN numbers and proper shipping names

Once the hazard class and packing group have been determined, the shipper must select an appropriate UN number and proper shipping name from the Dangerous Goods List in Chapter 3.2. If the dangerous good is listed by name, that name must be used. If the dangerous good is not listed by name a generic or not otherwise specified (n.o.s.) name must be used.