Overpack Label
“OVERPACK” Markings – Overdone?

The Issue

The formalization of the overpack concept into the Canadian TDG regulations has been the subject of concern for domestic shippers of dangerous goods due to the wording for fully regulated (TDGR 4.10.1) products. The wording implies that even when the DG safety marks for packages within the overpack are visible, the overpack must still have an “OVERPACK” mark displayed. This leads to some additional labelling requirements, particularly for shippers of stretch-wrapped pallet loads.


We’ll pause to review the concept of an overpack, consistent among the various regulations (e.g. TDG, UN Model Recommendations, IMDG, IATA, & 49 CFR).
An overpack is non-standardized packaging that:

  1. Is used for handling convenience (e.g. to reduce multiple handling- I.e. 4 drums on a skid, allowing loading 4 at once rather than 4 trips, or 6 small containers in a “non-spec” master carton, or 48 small boxes stretch wrapped on a skid; a keg (small drum) in a non-spec box for stability, etc. )
  2. Cannot be used as a replacement for inadequate, required “standardized” packaging
  3. Is to be unopened between consignor and receiver
  4. Cannot interfere with the integrity of the standardized packaging (e.g. banding cutting into boxes on a pallet)

The common principle requires that the description of DG that cannot be seen once the overpack is in place will be reproduced on the outside of the overpack.

However, this could be misleading in that someone seeing the DG markings may assume “non-compliance” when there is no package certification mark on the overpack. Although the situation should be fairly obvious with, for example, a stretch wrapped pallet; a master carton situation could be confusing.

Thus we have the application of the “overpack” mark to signal that the specification package is inside.

Different Strokes

The system starts to get sticky when the wording used in the different regulations is phrased differently.

TDGR speaks of “the marks on the small means of containment”- which implies that each package’s markings must be visible to avoid the need to reproduce them on the overpack.

Other regulations (49 CFR, IATA, IMDG, UN Recommendations) insert the words “representative of…” (all DG or each HazMat) in the overpack. Thus, as long as safety marks representing the individual packages can be seen at least once, there should be no need to reproduce any on the outside of the overpack.

Furthermore, the sequence of the clauses in TDGR 4.10.1 requires the use of an “overpack” mark whenever an overpack is used, regardless of the visibility of the standard safety marks.

Part 4.10.1 says that (1) (b) & (c) “do not apply if the safety mark… is visible through the overpack”; but the overpack mark requirement is in 1(a) which isn’t included in the exemption. This is in the spirit of the UN Recommendations where the placement of commas in implies that the lead-in requirement for an “overpack” mark applies even when the DG marks are visible.*

Neither IATA, DGR, nor the IMDG Code requires the word “overpack” to be applied if the DG safety marks are not required on the outside.

49 CFR puts a slightly different spin on things and requires an overpack mark only when packages in the overpack which require UN specification packaging do not have the UN specification marks visible.

Size Matters – Sometimes

The TDGR and 49 CFR both require safety marks on 2 opposite sides if the overpack volume is 1.8 cubic metres (approximately 64 cu.ft.) or more. IATA ans IMDG are silent on this aspect.

All except TDGR recommend “overpack” letters to be at least 12 mm high, warning that this will be mandatory January 1, 2016. Transport Canada has not yet commented on size of lettering.

Other Markings

Orientation arrows, as required by all but TDGR, must also be included for liquids.

IATA adds a requirement to assign a unique number to each overpack in a consignment when there is more than one. This numbering system is at the shipper’s discretion, but must be referenced on the Shipper’s Declaration for the consignment.

Limited/Excepted Quantities

All agree on waiving the need for any mark on an overpack consisting only of “limited” or “excepted” quantities when the DG marks are visible.

This would seem to be in accord with the concept that an “overpack” mark signals that, despite the safety marks on the outside, these materials by their classification do not require UN specification packaging.

Thus an observer/inspector trained to handle dangerous goods should not be confused when presented with these safety marks without the UN packaging markings.

*The UN Committee of experts was (as reported in the May edition of HCB) asked by Spain & Sweden to consider simplifying the wording of the model regulations. The CACD (Canadian Association of Chemical Distributers) has recommended that its members take a conservative approach to overpack labeling. The latter are hoping for a possible clarifying amendment to the TDGR later this year.

The “overpack” marking may be facilitated by the use of tape with repeating wording.



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