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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #19-0116

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name:

Individual Name: Robert Lewis

Country: US

View the Interpretation Document

Response text:

May 26, 2020

Mr. Robert L. Lewis, Jr.

Reference No. 19-0116

Dear Mr. Lewis:

This letter is in response to your October 3, 2019, and October 8, 2019, emails requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to hazardous material marking requirements for portable tanks. Specifically, you ask whether an IM 101 portable tank with a capacity greater than 1,000 gallons, but containing less than 1,000 gallons, can be marked with the UN identification number "2651" on a POISON placard (Division 6.1) on all four sides and with this same UN identification number on an orange panel on two opposing sides. You state that you encountered an IM 101 portable tank marked and placarded in this manner and enclosed a drawing representing the type and location of signage that you saw.

The HMR require an IM 101 portable tank that contains "UN2651, 4, 4"-Diaminodiphenyl methane, 6.1, Packing Group (PG) III," to be marked and placarded on each side and each end, as prescribed in §§ 172.326(c), 172.332, 172.503, and 172.504(a). However, a portable tank with a capacity less than 3,785 liters (1,000 gallons) may, alternatively, be placarded or labeled on only two opposing side sides as prescribed in § 172.514(c).

You also note that the portable tank is marked on two opposing sides with an additional orange panel that has the number "60" printed on it. The HMR requires orange panels be marked with a UN identification number only (see § 172.332(a) and (b)). The stacked orange panels with the top panel displaying two, three, or four characters is a European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) requirement (see ADR §§,, and 49 CFR Part 171, Subpart C (international regulations), permits marking in conformance with the International Civil Aviation Organization (ICAO) Technical Instructions, International Maritime Dangerous Goods or (IMDG) Code, or Canadian Transportation of Dangerous Goods (TDG) Regulations if a material is hazardous or a dangerous good under any of these regulations. The HMR do not recognize the ADR.

When a portable tank of hazardous material imported into the United States in conformance with the ICAO Technical Instructions, IMDG Code, or TDG Regulations is permitted to display ADR markings under these regulations, it may be offered for transportation and transported in the United States to its final destination under the regulatory structure to which it was prepared and offered, but within the limits set forth in the HMR. However, when reoffered for transportation wholly within the United States, to comply with the HMR, the orange panels you describe that contain the number "60" must be obscured or removed.

I hope this information is helpful. Please contact us if we can be of further assistance.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

172.326(c), 172.332, 172.332(a) and (b), 172.503, 172.504(a), 172.514(c),

Regulation Sections

Section Subject
172.326 Portable tanks
172.332 Identification number markings
172.503 Identification number display on placards
172.504 General placarding requirements
172.514 Bulk packagings