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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 #23-0102

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

Interpretation Response Details

Response Publish Date:

Company Name: American Industrial Transport, Inc.

Individual Name: Roger Dalske

Location State: MO Country: US

View the Interpretation Document

Response text:

March 28, 2024

Roger Dalske
Vice President Engineering and Fleet Operations
American Industrial Transport, Inc.
100 Clark Street
St. Charles, MO  63301

Reference No. 23-0102

Dear Mr. Dalske:

This letter is in response to your November 28, 2023, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to thermal protection systems on rail tank cars. You ask whether thermal protection systems included among the Department’s list of thermal protection systems that comply with the requirements of Part 179, Appendix B—and no longer require test verification per § 179.18(c) —can be combined. Specifically, you ask whether a different thermal protection system on the list may be used to repair a thermal protection system on the list that has already be installed on a tank car if the list does not specifically identify the two systems in use together. It is your understanding that it would be permissible to use one listed thermal protection system to repair another listed thermal protection system provided the tank car still meets the required performance standards set forth in the HMR, and that further test verification of the combined system would be unnecessary because separately both systems no longer require test verification.

Based on the information in your letter and the included plans for repair of the thermal protection system, it is the opinion of this Office that your understanding is incorrect. The thermal protection systems that comply with Part 179, Appendix B and no longer require test verification per § 179.18(c), provide readily available options to be used wholly. Combining pieces of two or more systems from the thermal protection systems list will require test verification in accordance with the requirements of § 179.18(a)-(b), as the systems on the list were not tested in combination.

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


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

179.18(c), 179.18(a)-(b)

Regulation Sections

Section Subject
179.18 Thermal protection systems