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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 #18-0036

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

Interpretation Response Details

Response Publish Date:

Company Name: Association of American Railroads

Individual Name: Kenneth B. Dorsey

Location State: DC Country: US

View the Interpretation Document

Response text:

September 18, 2018

Kenneth B. Dorsey
Association of American Railroads
425 Third Street, SW
Washington, DC  20024

Reference No. 18-0036

Dear Mr. Dorsey:

This letter is in response to your March 13, 2018, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to specifications for DOT-111 and DOT-117 series tank cars.

We have paraphrased and answered your questions as follows:

Q1. You ask whether a DOT-111 tank car manufactured after October 1, 2015, is eligible to be retrofitted to DOT-117R or DOT-117P specification.

A1. The answer is no.  In accordance with § 174.310(a)(4), a newly manufactured tank car used to transport flammable liquids must be built to the new DOT-117 or DOT 117P specifications.

Q2. Certain jacketed DOT-111 tank cars are equipped with fiberglass insulation, which is not an approved thermal protection system, in accordance with § 179.18(c).  You ask whether these tank cars being retrofitted to the DOT-117 specification require documentation of a worst-case thermal analysis for crude oil and ethanol to show that they are capable of achieving the performance standard in § 179.18(a).

A2. The answer is yes.  When converting jacketed DOT-111 tank cars equipped with a thermal protection system not on the verification list, a thermal analysis must be provided that demonstrates the tank car can achieve the performance standard in § 179.18(a).  In accordance with § 179.202-12(a), only cars that show they can meet this performance standard will be eligible for conversion to DOT-117P specification and need additional approval from Associate Administrator for Railroad Safety/Chief Safety Officer, Federal Railroad Administration (FRA).

Q3. You ask if the minimum plate thickness requirements for DOT-117R specification can be based on the minimum plate thickness requirement at the time of original construction.
 
A3. The answer is yes.  In accordance with § 179.202-13(c), the minimum plate thickness for all tank cars manufactured to the DOT-117R is 7/16 of an inch.  However, DOT-111 tank cars manufactured to the Association of American Railroads CPC-1232 standard have a minimum plate thickness of ½ an inch.  Additionally, when calculating minimum allowable tank shell thickness in accordance with § 180.509(f), the original plate thickness at time of construction must be used for these calculations.

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

Sincerely,

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

174.310(a)(4), 179.18(c), 179.18(a), 179.202-12(a), 179.202-13(c), 180.509(f)

Regulation Sections

Section Subject
179.18 Thermal protection systems
179.202-12 Performance standard requirements (DOT-117P)
179.202-13 Retrofit standard requirements (DOT-117R)
180.509 Requirements for inspection and test of specification tank cars