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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 #18-0130

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

Interpretation Response Details

Response Publish Date:

Company Name: Hogan Lovells US LLP.

Individual Name: Emily Kimball

Location State: CO Country: US

View the Interpretation Document

Response text:

May 09, 2019

Emily Kimball
Senior Associate
Hogan Lovells US LLP
1601 Wenwatta Street, Suite 900
Denver, CO  80202

Reference No. 18-0130

Dear Ms. Kimball:

This letter is in response to your October 11, 2018 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the thermal analysis requirements for certain tank cars. Specifically, you ask what documentation must accompany an application for approval by the American Association of Railroads for a tank car owner seeking to convert a legacy DOT-111 specification tank car equipped with a thermal protection system consisting of a jacket, fiberglass insulation, and pressure relief valve to a DOT-117R specification tank car. You state that it is your understanding that a 2016 AFFTAC study of tank cars equipped with this configuration, and which shows survival times for ethanol and most common crude oil commodities, demonstrates the tank cars are compliant with the thermal protection system performance standard of § 179.18(a). Furthermore, the Railway Supply Institute (RSI) provided this study to the Federal Railroad Administration (FRA) and whom, in consultation with PHMSA, responded in a November 23, 2016 letter with a determination that the study addressed the thermal analysis requirements.

Your understanding is correct. The AFFTAC study provided to FRA/PHMSA is an acceptable manner of documentation of thermal analysis for approval of DOT-111 tank car conversion to DOT-117R specification tank cars, provided it is representative of the owner's tank cars. Additionally, the tank cars equipped with the thermal protection system should otherwise comply with all specification requirements for a DOT-117R in § 179.202-13. Section 179.18(b) sets forth the requirements for verifying that a tank car meets the performance standard in § 179.18(a). Further, § 179.18(b)(1) states that each tank car owner must retain and make available for inspection and copying by an authorized representative of the Department a complete record of each analysis. 

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


Shane C. Kelley
Standards and Rulemaking Division
Office of Hazardous Materials Safety

179.18(a), 179.18(b), 179.18(b)(1)

Regulation Sections

Section Subject
179.18 Thermal protection systems
179.202-13 Retrofit standard requirements (DOT-117R)