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Transportation of Dangerous Goods (TDG): Overpack & Markings Legislation Changes

By Corie Doyle
Published: September 8, 2016 | Last updated: October 17, 2021
Presented by Danatec
Key Takeaways

SOR/2014-159 came into force January 15, 2015. This is what it means for you.

Source: JohnnyHabell/

Overpack Definition & TDG Regulations

Means an enclosure that is used by a single consignor to consolidate one or more small means of containment for ease of handling but that is not a minimum required means of containment. This definition does not include a large means of containment or a unit load devise (ULD), as defined in the ICAO Technical Instructions, which is intended for transport by Aircraft. Examples of overpacks include:

  • A pallet on which are placed or stacked one or more small means of containment that are secured by strap, shrink wrap, stretch wrap, nets or other similar means.
  • A disposable box, crate or bin in which one or more small means of containment are placed.
  • All modes of transport Air (IATA), Water (IMDG) and Ground (TDGR & 49CFR) have basically the same definition of an overpack.

Safety Marks TDG

Regulations section 4.10.1

A. When a safety mark is required by this Part to be displayed on a small means of containment and the small means of containment is inside an overpack, the person who prepares the overpack must display:

  1. The word “Overpack” or “Suremballage” on at least one side of the overpack;
  2. The information required by subsection (3) on one side of the overpack, if its capacity is less than 1.8 cubic metres (64 cubic feet); and
  3. The information required by subsection (3) on two opposite sides of the overpack, if its capacity is greater than or equal to 1.8 cubic metres (64 cubic feet).

B. Paragraphs (A)(2) and (3) do not apply if the safety mark on the small means of containment is visible through the overpack. (so you still have to put the word “overpack” on all overpacks even if all the safety marks are visible!)

C. The following information must be displayed on the overpack:

  1. The primary class label and each subsidiary class label for each of the dangerous goods contained in the overpack, except that only one label is required for dangerous goods that are included in the same class; and
  2. The shipping name and UN number of the dangerous goods.

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Regulation Differences

The wording of each set of regulations are different, so you must be careful with the interpretation. IATA regulations states in; Unless all markings representative of all dangerous goods in the overpack are clearly visible, the overpack must be marked with the word “overpack”.

I asked the question regarding the word REPRESENTATIVE to Brendan Sullivan, Head, Cargo Operations at IATA and this was his reply:

"The intention is that only one box and the relevant marks are required (assuming they are identical). However, it starts to get a little complicated with UN Specification Packages, it would be impossible to tell whether the UN Specification marking you can see is “representative” of the dangerous goods marking within the package. Previously we had packages inside comply with prescribed specifications, which was a clearer indication, but that is now gone. So I think that for an overpack of UN Specifications packages, you are either going to have to have all the UN Spec marks visible and the other package marks representative or you will need to show “overpack” on the outside."

49 CFR regulations and IMDG regulations are similar with this statement, the overpack is marked with the word “overpack”, the proper shipping name and UN number and is labeled as required for each dangerous goods contained therein, unless markings and labels representative of each hazardous material in the overpack are visible. Only the TDG Regulations requires the use of an “overpack” mark whenever an overpack is used, regardless of the visibility of the Dangerous Goods Marks.


The upright/orientations arrows are required on the overpack for liquids on all modes of transport except for the TDG Regulations. TDG and 49 CFR both require safety marks on two opposite sides if the overpack volume is 1.8 cubic meters or more, this is not applicable to IATA and IMDG regulations.

Free Webinar - Transportation of Dangerous Goods (TDG) Q&A with Live Discussion


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Written by Corie Doyle | Product Development Manager

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Corie is a mom, wife, daughter, sister, and friend, and keeping her family and friends safe is the foundation for her passion for safety.

She began her career as a Nuclear Medicine Technologist in British Columbia, then moved into radiochemical production and safety.

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