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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 #09-0046 ([Honeywell] [Ms. Claire Matlon Leader])

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

Interpretation Response Details

Response Publish Date:

Company Name: Honeywell

Individual Name: Ms. Claire Matlon Leader

Location State: NJ Country: US

View the Interpretation Document

Response text:

September 21, 2009




Ms. Claire Matlon

Leader, Transportation Regulatory Compliance


101 Columbia Road

Morristown, NJ 07962-1057

Ref. No.: 09-0046

Dear Ms. Matlon:

This responds to your February 12, 2009 letter requesting clarification of the packaging requirements for a shipment of UN 1790, Hydrofluoric acid with more than 60% strength in an unlined class DOT 111 tank car in accordance with 49 CFR 173.243, and Special provisions B15 and B23 in §172.102. Your questions are paraphrased and answered below:

Q1. If a pressure DOT 112S340W tank car tank is re-rated to a non-pressure DOT 111A100W2 tank car, may the tank car be used to transport Hydrofluoric acid with more than 60% strength?

A1. Yes. Section 173.243(a) authorizes class DOT 111 tanks for Hydrofluoric acid with more than 60% strength. Special provision B15 requires an unlined tank used to transport this material to have a suitable corrosion allowance. The determination of whether the DOT 112S340W tank will provide suitable corrosion allowance as well as an appropriate inspection interval based on the known corrosion rate must be made using the requirements of § 180.509.

Q2. May a 70% concentration by weight of hydrofluoric acid that does not exceed the corrosion rate of hydrofluoric acid of 65% concentration, be shipped in the described class DOT 111 tank?

A2. Yes, as stated above. Special provision B23 requires the lading in an unlined tank to be inhibited so that the corrosive effect on steel is not greater than that of a 65 percent concentration of hydrofluoric acid. Therefore, if, as you state, the corrosive effect on steel of your 70% concentration of hydrofluoric acid is not greater than that of a 65% concentration of hydrofluoric acid, the lading may be transported in the unlined class DOT 111 tank. Note that Special provision B23 requires an unlined tank to be passivated before being placed in service and re-passivated each time after being washed out with water.

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


Hattie L. Mitchell

Chief, Regulatory Review and Reinvention

Office of Hazardous Materials Standards

172.102, 173.243(a)

Regulation Sections

Section Subject
172.102 Special provisions
173.243 Bulk packaging for certain high hazard liquids and dual hazard materials which pose a moderate hazard
180.509 Requirements for inspection and test of specification tank cars