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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 #22-0046

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

Interpretation Response Details

Response Publish Date:

Company Name: Entegris Inc.

Individual Name: Jim McManus

Location State: CT Country: US

View the Interpretation Document

Response text:

August 22, 2022

Jim McManus
Entegris Inc.
7 Commerce Drive
Danbury, CT  06810

Reference No. 22-0046

Dear Mr. McManus:

This letter is in response to your April 21, 2022, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to shipping paper and hazard communication requirements. You describe a package that is intended for transport by cargo only aircraft containing a Division 4.2 hazardous material, "UN2881, Metal catalyst, dry, 4.2, PG II," covered under DOT Special Permit (DOT-SP) 11447 and Competent Authority Approval (CA1995070006). You further describe the package as a gas purification system that consists of two non-DOT specification stainless steel pressure vessels—though the contents are not under pressure subject to the HMR—with component parts (e.g., piping), and a welded steel frame to secure the pressure vessels. You seek clarification on how to properly describe on the shipping paper the type of package and the quantity of material contained in the pressure vessels, and how to properly mark and label the assembled package.

It is the shipper's responsibility to properly classify and describe a hazardous material and provide the required hazard communication, such as shipping paper information, in accordance with Part 172 of the HMR, to alert emergency response personnel to the presence, form and manner of hazardous materials offered into transportation. For instance, the HMR require the total net mass per package and the number and type of package(s) be indicated on the shipping paper. However, the unique circumstances of the containment device in DOT-SP 11447 —i.e., a gas purification system—makes it more difficult to describe than a standalone package (e.g., a drum). PHMSA notes that both DOT-SP 11447 and CA1995070006 provide details about the hazardous material, the package, and the transport requirements—and that the special permit is required to accompany the shipment and be given to the air carrier. Finally, PHMSA also notes that for purposes of hazard communication, the HMR require that packages placed in overpacks have markings and labels displayed on the overpack unless otherwise visible. See §§ 172.202(a)(6) and (7), and 173.25(a)(2), respectively.

Given this information, it is the opinion of this Office that all three examples that you provided regarding the description of the quantity and type of package are acceptable under the HMR. However, the indication of "pressure vessels" when described on a shipping document may be misunderstood as containing contents under pressure subject to specific HMR requirements. Further, it is acceptable to place the required marking and labeling on the exterior of the gas purification system—such as an access panel door—with the understanding that this will be obscured by the wooden crate overpack, thus requiring the overpack to also have the required marking and labeling displayed.

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


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

173.25(a)(2), 172.202(a)(6), 172.202(a)(7)

Regulation Sections

Section Subject
173.202 Non-bulk packagings for liquid hazardous materials in Packing Group II
173.25 Authorized packagings and overpacks