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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 #12-0188 ([Enservco] [Mr. Don Custer])

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

Interpretation Response Details

Response Publish Date:

Company Name: Enservco

Individual Name: Mr. Don Custer

Location State: CO Country: US

View the Interpretation Document

Response text:

January 22, 2013

Mr. Don Custer
Safety Coordinator
501 S. Cherry Street, Suite 320
Denver, CO 80246

Ref. No.: 12-0188

Dear Mr. Custer:

This responds to your August 14, 2012 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to truck- or trailer-mounted oilfield water heating units with integral burners fueled by propane gas.  The propane gas is transported in MC 331 specification tanks constructed in accordance with the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code).  The tanks are mounted to the same trailer as the heating units.  You ask whether the water heating units you describe in your letter are subject to the HMR and, if not, if you can voluntarily communicate the hazards posed by transporting such units on a public highway without being penalized for not complying with additional requirements in the HMR.

As defined in 49 CFR § 171.8, a fuel tank means "a tank, other than a cargo tank, used to transport flammable or combustible liquid, or compressed gas for the purpose of supplying fuel for propulsion of the transport vehicle to which it is attached, or for the operation of other equipment on the transport vehicle."  Fuel systems that meet the requirements under 49 CFR §§ 393.65 and 393.67 of the Federal Motor Carrier Safety Regulations (FMCSRs) and are not used as packaging for hazardous materials are subject only to the FMCSRs.  As prescribed in 49 CFR § 393.69(a), a fuel system that uses liquefied petroleum gas as a fuel for the operation of a motor vehicle or for the operation of auxiliary equipment installed on, or used in connection with, a motor vehicle must conform to the "Standards for the Storage and Handling of Liquefied Petroleum Gases" of the National Fire Protection Association (NFPA), Battery March Park, Quincy, MA 02269. 

It should be noted that, while MC 331 specification tanks may be used to package a material not subject to the HMR, no person may represent or offer a packaging as meeting the requirements of the HMR unless the packaging is maintained, marked, and retested in accordance with the applicable requirements of the HMR.  These requirements are applicable whether or not the packaging is used for the transportation of a hazardous material.  Therefore, if the tank is not maintained in accordance with the HMR, we recommend you securely cover any identifying marks or specification plates representing it as such.

With respect to your question regarding placarding, the HMR do not prohibit placarding, provided you meet the requirements in § 172.502.  However, you should be aware that placarding a package or fuel tank that does not otherwise comply with the HMR may frustrate your shipment.

I hope this information is helpful.  If you have further questions, please do not hesitate to contact this office.


Delmer Billings
Senior Regulatory Advisor
Standards and Rulemaking Division

171.8, 172.502

Regulation Sections

Section Subject
171.8 Definitions and abbreviations
172.502 Prohibited and permissive placarding