USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #17-0083

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

Interpretation Response Details

Response Publish Date:

Company Name: Gold Tank Inspection Service Inc.

Individual Name: Aris Antoniou

Location State: TX Country: US

View the Interpretation Document

Response text:

January 19, 2018

Aris Antoniou
Gold Tank Inspection Service Inc.
P.O. Box 5638
Kingwood, TX 77325

Reference No. 17-0083

Dear Mr. Antoniou:

This letter is in response to your July 14, 2017, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to United Nations (UN) portable tanks. Specifically, you ask whether it was the Pipeline and Hazardous Materials Safety Administration's (PHMSA) intent to reduce the design margin (safety factor) for UN portable tanks when it incorporated by reference (IBR) the 2015 Edition of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) into the HMR on May 31, 2016, in the final rule titled "Incorporation by Reference Edition Update for the American Society of Mechanical Engineers Boiler and Pressure Vessel Code and Transportation Systems for Liquids and Slurries: Pressure Piping Code" [Docket No. PHMSA-2015-0271 (HM-261)]. You cite a letter of interpretation issued by this Office to Mr. Mike Pitts on July 1, 2016, that acknowledges the reduced design margin allowed in the 2015 ASME Code (3.5:1) was not applicable to U.S. Department of Transportation (DOT) specification cargo tanks unless under the terms of a special permit.

As prescribed in § 178.273 of the HMR, UN portable tanks must be designed, constructed, certified, and stamped in accordance with the requirements in Division I, Section VIII, of the ASME Code IBR in § 171.7. Further, the reduced design margin prescribed in Division I, Section VIII, of the 2015 ASME Code (3.5:1) is authorized for UN portable tanks. Thus, the reduced design margin restriction applicable to DOT specification cargo tanks does not apply to UN portable tanks manufactured in accordance with Division I, Section VIII, of the 2015 ASME Code. The IBR, however, does not include changes to currently adopted ASME Boiler and Pressure Vessel Code rules (i.e., code cases). Any variation from the HMR would require a special permit from PHMSA.

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


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

§ 178.273, 171.7

Regulation Sections

Section Subject
171.1 Applicability of Hazardous Materials Regulations (HMR) to persons and functions
178.273 Approval of Specification UN portable tanks