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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 #20-0059

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:

December 10, 2020

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

Reference No. 20-0059

Dear Mr. Antoniou:

This is in response to your July 29, 2020, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to United Nations (UN) portable tanks. Specifically, you describe a scenario in which an internal stop-valve on a UN portable tank has no spring and the valve must be closed by manually turning a lever.

We have paraphrased and answered your questions as follows:

Q1. You ask whether the internal stop-valve on the bottom discharge outlet of a UN portable tank must be self-closing or if it may be manually operated by turning a lever.

A1. Except as provided in 49 CFR § 178.275(d)(2), every bottom discharge outlet on a UN portable tank must be equipped with three serially fitted and mutually independent shut-off devices. The design of the equipment must include a self‑closing internal stop-valve, among other requirements. While a spring‑loaded valve is the most common type of self‑closing internal stop-valve, this design type is not specified in 49 CFR § 178.275(d)(3). However, any valve which closes independently without human operation, such as turning a lever, is considered "self‑closing."

Q2. You ask whether the presence of a lining changes the applicability of the requirements in 49 CFR § 178.275(d)(3).

A2. No. The requirements for bottom discharge outlets are the same for lined and unlined UN portable tanks.

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

178.275(d)(2), 178.275(d)(3)

Regulation Sections

Section Subject
178.275 Specification for UN Portable Tanks intended for the transportation of liquid and solid hazardous materials