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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 #13-0003

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

Interpretation Response Details

Response Publish Date:

Company Name: Air Liquide USA LLC

Individual Name: Mr. Jerry W. Freeman

Location State: TX Country: US

View the Interpretation Document

Response text:

March 8, 2013

Mr. Jerry W. Freeman
Director, Transportation Compliance
Air Liquide USA LLC
2700 Post Oak Boulevard, Suite 1800
Houston, TX  77056

Reference No. 13-0003

Dear Mr. Freeman:

This is in response to your December 3, 2012 letter requesting clarification on the proper classification and shipping description of "Trisilylamine" (CAS No. 13862-16-3) under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). You state this chemical is a liquid developed for use in the semiconductor industry. You also state the material was tested in conformance with the hazardous material classification criteria prescribed in the HMR and determined to meet the following four hazard classes in order of precedence:

  • Division 6.1 (poisonous), Packing Group (PG) I, Hazard Zone B;
  • Division 4.3 (dangerous when wet), PG I;
  • Class 8 (corrosive, dermal), PG I;
  • Class 3 (flammable liquid), PG II.

You ask if the proper shipping description "UN 3491, Toxic by inhalation, liquid, water-reactive, flammable, n.o.s. (Trisilylamine), 6.1, (4.3, 3), PG I, Zone B" is the most appropriate selection for shipping this material throughout the United States and internationally.

The answer is yes. However, for transport within the United States in accordance with the HMR, § 172.402(a)(2) requires all hazardous materials with a Class 8, PG I, subsidiary hazard to be labeled with a subsidiary CORROSIVE hazard warning label in all modes of transport. Therefore, the subsidiary hazard class must be entered in the proper shipping description as well (see § 172.202(a)(3)).

I hope this satisfies your request.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

172.202, 172.402

Regulation Sections

Section Subject
172.202 Description of hazardous material on shipping papers
172.402 Additional labeling requirements