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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 #18-0154

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

Interpretation Response Details

Response Publish Date:

Company Name: Commercial Vehicle Safety Alliance

Individual Name: Collin B. Mooney

Location State: MD Country: US

View the Interpretation Document

Response text:

August 7, 2019

Collin B. Mooney, MPA, CAE
Executive Director
Commercial Vehicle Safety Alliance
6303 Ivy Lane, Suite 310
Greenbelt, MD 20770-6319

Reference No. 18-0154

Dear Mr. Mooney,

This letter is in response to your December 4, 2018, emails and letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the requalification testing of cargo tanks. Specifically, you ask four questions concerning the 10-year internal visual inspection and the 10-year pressure test required for MC 331 cargo tanks in dedicated propane service prescribed in § 180.407(c).

We have paraphrased and answered your questions as follows:

Q1. You ask whether the 10-year internal visual inspection and pressure retest intervals in the § 180.407(c) Table only apply to MC 331 bobtail tank trucks (i.e., the cargo tank is permanently mounted on a truck chassis), with a capacity less than 3,500 gallons in dedicated propane service, or if they also apply to MC 331 cargo tanks mounted on trailers.

A1. The 10-year retest exception in § 180.407(c) applies to all MC 331 cargo tanks of 3,500 gallons or less, constructed of the specified non-quenched and tempered (NQT) steel(s), and used in dedicated propane service. In addition, the 10-year retest requirement applies to all MC 331 cargo tanks meeting the exception whether the cargo tank is permanently mounted on a truck chassis, trailer, or other structure.

Q2. You ask whether a motor carrier may fill a cargo tank with "UN1978, Propane, 2.1 (flammable gas)" and use the exception provided in § 172.102(c)(1), Special Provision 19, to qualify the cargo tank for the 10-year pressure retest and internal visual inspection.

A2. Provided the cargo tank is in dedicated propane service, the answer is yes. Special Provision 19 permits the identification number "UN1075" to be used in place of the identification number specified for the hazardous material in column 4 of the § 172.101 Hazardous Materials Table (HMT) (e.g., "1978"). Further, when one proper shipping name entry in column 2 of the HMT references another entry by use of the word "see," any entry in Roman type that follows may be used as the proper shipping name for that hazardous material (e.g., Propane, see Petroleum gases, liquefied or Liquefied petroleum gas). Thus, propane may be described as "UN1978, Propane," "UN1075, Propane," "UN1075, Petroleum gases, liquefied," or "UN1075, Liquefied petroleum gas."

Please note the 10-year pressure retest exception does not apply to other gases with Special Provision 19 assigned to them in column 7 of the HMT (e.g., Butane or Propylene). Special Provision 19 requires that the identification number "1075" be used consistently in all places the identification number appears (e.g., shipping papers, package marking, and/or emergency response information).

Q3. You ask whether the product must be 100 percent propane, or if it can be described as propane and be a mix of propane and other liquefied petroleum gases if propane is the primary gas in the mixture and the material is shipped as propane, consistent with industry standards.

A3. The propane transported does not need to be 100 percent pure propane to meet the requirements of the 10-year retest exception. The propane may be in a gas mixture provided the proper shipping name is "Propane" when not using one of the alternate proper shipping names or identification number permitted under Special Provision 19.

Q4. You ask whether carriers must keep a copy of the full-size equivalent (FSE) Charpy V-notch (CVN) energy test data required for cargo tanks in dedicated propane service, made of the required NQT steel(s), in the vehicle to take advantage of the 10-year retest in § 180.407(c).

A4. The answer is no; the HMR do not require carriers to maintain a copy of the test data on the transport vehicle. The HMR do not specify, or limit, the location(s) where such test data may be kept. However, in accordance with § 180.417(b)(3) of the HMR, each owner of a cargo tank and, except for a motor carrier who leases a cargo tank for less than 30 days, each motor carrier who uses a cargo tank must retain copies of the test data to be eligible for the 10-year retest in § 180.407(c). In other words, if the cargo tank owner and motor carrier, when the cargo tank is leased for 30 days or more, does not retain a copy of the test report, the cargo tank must be retested every 5 years in accordance with § 180.407(c).

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

180.407(c), 172.102(c)(1), 172.101, 180.417(b)(3)

Regulation Sections

Section Subject
172.101 Purpose and use of hazardous materials table
172.102 Special provisions
180.407 Requirements for test and inspection of specification cargo tanks