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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 #24-0007

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

Interpretation Response Details

Response Publish Date:

Company Name: ABC Nitrogen Service Corp

Individual Name: Aimee Fontenot

Location State: TX Country: US

View the Interpretation Document

Response text:

March 27, 2024

Aimee Fontenot
DOT Coordinator
ABC Nitrogen Service Corp
11425 I-10 East
Baytown, TX  77523

Reference No. 24-0007

Dear Ms. Fontenot:

This letter is in response to your January 26, 2024, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to placarding requirements for transportation of nitrogen, refrigerated liquid (cryogenic liquid). You state that your company transports nitrogen in insulated cargo tanks designed and constructed so that the pressure in such packagings will not exceed 25.3 psig under ambient temperature conditions during transportation in accordance with § 173.320(a). It is your understanding that this transportation is excepted from certain requirements of the HMR. Specifically, you ask whether hazard placards are required on insulated cargo tanks that transport "UN1977, Nitrogen, refrigerated liquid cryogenic liquid, 2.2" in this manner.

The answer is no. Placards are not required on the insulated cargo tanks used for carriage of "UN1977, Nitrogen, refrigerated liquid cryogenic liquid, 2.2" when transported in accordance with the conditions of § 173.320(a). The exceptions contained in § 173.320 are applicable to the transportation by motor vehicle and railcar of "atmospheric gases" such as nitrogen—see § 171.8—and helium, cryogenic liquids, in select packagings, including insulated cargo tanks, designed and constructed so that the pressure in such packagings will not exceed 25.3 psig under ambient temperature conditions during transportation. This includes exception from the Subpart F of Part 172 placarding requirements of the HMR.

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

Sincerely,

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

173.320(a), 173.320, 171.8

Regulation Sections

Section Subject
171.8 Definitions and abbreviations
173.320 Cryogenic liquids; exceptions