A bulk packaging is a packaging, other than a vessel or a barge, with (1) a maximum capacity greater than 450 liters (119 gallons) as a receptacle for a liquid; (2) a maximum net mass greater than 400 kilograms (882 pounds) and a maximum capacity greater than 450 liters (119 gallons) as a receptacle for a solid; or (3) a water capacity greater than 454 kilograms (1000 pounds) as a receptacle for a gas.

The distinction between bulk and non-bulk packagings is important in determining whether the placarding requirements apply (click here to see a summary of the placarding requirements). All shipments that require placarding also require registration. Hazardous materials (particularly Class 9 hazardous wastes) that do not require placarding but are transported in bulk packagings with capacities greater than 3,500 gallons or 468 cubic feet require registration under category D. However, shipments of hazardous materials that do not require placarding (for example, Class 9 materials), placed in bulk packagings with capacities less than 3,500 gallons or 468 cubic feet, do not require registration.

It is important to note that the use of bulk packagings requires registration no matter how small the quantity of hazardous materials actually offered or transported. For example, persons who have hazardous waste picked up in tank trucks, and persons who return unpurged tank trucks or rail tank cars from which they have unloaded hazardous materials so that the tanks still contain residues of hazardous materials when returned, must register under the provisions of Category F (or Category D if the material is a Division 6.2 or Class 9 material).