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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 #21-0115

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

Interpretation Response Details

Response Publish Date:

Company Name: Intermodal Tank Transport

Individual Name: Jasmine Builes

Location State: TX Country: US

View the Interpretation Document

Response text:

March 9, 2022

Jasmine Builes
Intermodal Tank Transport
10720 West Sam Houston Parkway North Suite 250
Houston, TX  77064

Reference No. 21-0115

Dear Ms. Builes:

This letter is in response to your December 7, 2021, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the use of NA identification (ID) numbers outside of the United States. Specifically, you ask about the international shipment of a specific diacetone alcohol material, which has a flashpoint above 140 °F and below 200 °F, making it subject to regulation in the United States as a combustible liquid, yet unregulated when shipped internationally by vessel, according to the International Maritime Dangerous (IMDG) Code. Moreover, you state that this material was transported internationally with placards and labels using the ID number "NA1993".

You state that the shipper experienced frustration of shipment when transporting to Belgium because the material was described as a hazardous material. You seek confirmation that this specific diacetone alcohol material is regulated domestically within the United States and not regulated in accordance with the IMDG Code.

Your understanding is correct. ID numbers preceded by the letters "NA"—such as "NA1993"—are associated with proper shipping names not recognized for transportation outside of the United States, and therefore, would not be recognized by international competent authorities such as those in Belgium. This material is classified as a "combustible liquid" subject to regulation under the HMR.

The Dangerous Goods List of the IMDG Code, section, specifically excludes liquids with a flashpoint above 60 °C (140 °F) from the definition of a flammable liquid; therefore, this material is excepted from classification as a Class 3 hazardous material and is not subject to regulation under the IMDG Code.

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


Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division

171.23, 173.120, 172.101 (b)(3)

Regulation Sections

Section Subject
171.23 Requirements for specific materials and packagings transported under the ICAO Technical Instructions, IMDG Code, Transport Canada TDG Regulations, or the IAEA Regulations
172.101 Purpose and use of hazardous materials table
173.120 Class 3-Definitions