Generally, one can assume that the use of the Identification Number in association with the placard for a shipment of a hazardous material is limited to those shipments that are or contain a bulk packaging.

The identification number marking included on the placard affixed to a bulk packaging (Tank Truck) of a hazardous material

Such as:

• The transport vehicle itself is a bulk packaging of greater than 1,000 gallons (eg. tank truck or railroad tank car).
• A bulk packaging of any volume (eg. intermediate bulk packaging or IBC) is loaded into a transport vehicle where its identification number is no longer visible.

In either of the above, the Hazardous Material Regulations of the USDOT/PHMSA require that the transport vehicle be marked on both sides and each end with the identification number of the hazardous material.  The identification number used must be determined from the Hazardous Materials Table and be displayed in association with the hazardous materials placard as required by §172.332 or §172.336 (either on an orange panel or a white square-on-point configuration).

You may wish to read this earlier article for an exception to this marking requirement for certain shipments of bulk packagings.

Often overlooked by shippers and carriers alike, however, is the requirement in 49 CFR 172.301(a)(3) to mark a transport vehicle or freight container containing only a single hazardous material in non-bulk packages, on each side and each end with the identification number specified for the hazardous material in the § 172.101 Table, as long as the following requirements are met:

•  Each package is marked with the same proper shipping name and identification number;
• The aggregate gross weight of the hazardous material is 4,000 kg (8,820 pounds) or more;
• All of the hazardous material is loaded at one loading facility;
• The transport vehicle or freight container contains no other material, hazardous or otherwise; and
• The identification number marking requirement of this paragraph (a)(3) does not apply to Class 1, Class 7, or to non-bulk packagings for which identification numbers are not required.

Example:

Company A offers for shipment 20 x 55 gallon drums of Chromic Acid Solution weighing 11,009 pounds.  The carrier makes the pickup of the Chromic Acid Solution and nothing else, and has no other material (hazardous or otherwise) loaded on the vehicle.  In this situation, it is necessary to include the identification number for Chromic Acid Solution (UN1755) either on the placard or nearby as required by §172.332 or §172.336 (either on an orange panel or a white square-on-point configuration).

As you can see, the Hazardous Materials Regulations of the USDOT/PHMSA can be very complicated.  Even the seemingly simple regulations pertaining to the use of the identification number marking on a transport vehicle or freight container can become difficult to comply with when certain situations arise.  Training your HazMat Employees on the requirements of the HMR is a good way to ensure the transportation of hazardous materials to and from your facility is done safely and in compliance with the regulations.