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Facts at your Fingertips: UN Codes for Packaging Dangerous Goods

By Scott Jenkins, Chemical Engineering magazine |

Shipping and transport of chemicals require specialized packaging to mitigate the hazards that the chemicals may present. Only packages that are certified to have met testing standards issued by the United Nations (UN) Economic and Social Council (New York, N.Y.; can be used to transport dangerous goods, which include most chemicals. The UN has developed a code system for classifying packaging and containers for dangerous materials. This one-page reference explains the UN packaging code designations and provides information on the categories for each.

UN codes

All packages and containers manufactured to be “UN-approved” for holiding potentially dangerous materials are marked with a code that indicates the properties of the container and the physical nature of the product it contains. The UN packaging codes begin with a either a capital “UN” or symbol with a lowercase “u” above a lowercase “n” inside a circle (Figure 1). The codes consist of a series of numbers and letters usually stamped into metal or plastic drums and intermediate bulk containers (IBCs), and are printed on boxes and bags. Packages without the UN certification mark should not be used for dangerous goods.

Figure 1. Each position in the UN packaging code signifies specific information

Figure 1. Each position in the UN packaging code signifies specific information

The “UN” at the beginning of the code states that the package meets the performance standards set forth in the UN Recommendations on the Transport of Dangerous Goods Model Regulations (Orange book) [1]. The code’s numbers and letters each provide information about categories into which the contained substance falls. Information on what each component of the code means is provided in Table 1 and Refs. 2–4.

The code also includes a year and country, indicating the date and location of the manufacture of the packaging container.


Packing groups

Dangerous goods are classified into one of three UN Packing Groups: I, II and III, according to the degree of danger they present. Packing group I represents high danger, while Group II is medium danger and Group III presents low danger.

A key point for shippers with regard to UN packaging ratings is that “overpackaging” is appropriate, but “underpackaging” is not. That is, shippers can use containers that are rated for higher than the properties of the material within, but not lower. For example, for materials in packing Group II, either a X- or Y-rated container is acceptable, but a Z-rated container cannot be used. Packages for Packing Group I will be built to a higher standard and therefore will be more expensive than packages of the same type built for a lower packing group.


1. United Nations Economic and Social Council’s Committee of Experts on the Transport of Dangerous Goods, UN Model Regulations: UN Recommendations on the Transport of Dangerous Goods, 19th Revision, Parts 4 and 6. United Nations, New York, 2015.

2. New Pig Corp., Cracking the Code: Explaining UN Ratings, New Pig Blog,, Post accessed June 2018.

3. Tasker, Simon, A guide to chemical packaging, posted to ReAgent Blog (, February 2012.

4. Label Master, UN Markings Guide, Resources,; accessed June 2018.

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