One of our trade association members asked whether the materials that are placed into an overpack must be the same, or if they can be different? We received a related question about whether an overpack can consist of only one item.
An overpack. Image from Basic Crating & Packaging, Inc.
What is an Overpack?
When shipping hazardous materials, an overpack is an enclosure used for protection or convenience in the handling of packages. Examples of overpacks can include properly prepared packages assembled together under shrink-wrap on a wooden pallet, or a set of properly prepared packages placed together into a larger fiberboard box (used as a protective outer packaging). One key fact here is that there are properly prepared packages of hazardous material, and each such package stands on its own for purposes of compliance to the relevant hazardous materials/dangerous goods regulations. These properly prepared packages are then placed into another containment, and that other containment is the overpack.
Mixed Material Overpacks
The first member question was whether the materials in an overpack need to be the same substances. They do not. One may overpack different things in the same overpack, as long as no rule precludes them from being packed together. Examples of rules that would preclude certain materials from being packed together include:
- the overpack limitations on PG I materials in division 5.1 or class 8 found at 49 C.F.R. § 173.25(a)(5)
- the explosives mixed packaging rules found at 49 C.F.R. § 173.61,
- the rail segregation rules found at 49 C.F.R. § 174.81, and
- the highway segregation rules found at 49 C.F.R. § 177.848).
Mixing of materials is also permitted under international standards: there is an example of this in the IATA Dangerous Goods Regulations (61st Edition) at Figure 8.1.K – this figure is a sample Dangerous Good Declaration that shows motor spirits and aerosols being overpacked together.
The United States rules on overpacks are found at 49 C.F.R. § 173.25.
Single-Item Overpacks
The second question we received was about whether an overpack can consist of only one item. It may.
There is no requirement in the United States regulations nor in the ICAO (IATA) rules that an overpack must consist of more than one properly configured package. In fact, an overpack may contain one item, or more than one item and it may contain a combination of both properly packaged hazardous materials and also non-hazardous materials.
Examples of situations where you might want to create an overpack for a single properly packaged hazardous material include:
- Convenience: If one needs to use a forklift to place the item on a high shelf, then one might shrink-wrap the package onto a wooden pallet in order to make it easier to manipulate with a forklift.
- Protection: If one is expecting the package to be exposed to extreme weather, then one might place a package that is based on a fiberboard box into a plastic drum as an overpack to protect the box from getting wet.