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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 #17-0020

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

Interpretation Response Details

Response Publish Date:

Company Name: Keehn Service Corporation

Individual Name: Stephen Kovacic

Location State: PA Country: US

View the Interpretation Document

Response text:

Stephen Kovacic
Keehn Service Corporation
99 N. 11th Avenue
Coatesville, PA  19320

Reference No. 17-0020

Dear Mr. Kovacic:

This letter is in response to your February 13, 2017, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the marking requirements for a Department of Transportation (DOT) Specification MC 331 cargo tank. Specifically, you ask if § 178.337-9(c) allows the inlet/outlet marking to be placed on guarding, supports, or interlock paddles on an MC 331 cargo tank as it relates to guidance offered in a previously-issued letter of interpretation. You also provide photographs illustrating the placement of your markings on an MC 331 cargo tank motor vehicle.

The answer is yes. In accordance with § 178.337-9(c), each cargo tank inlet and outlet, with the exception of gauging devices, thermometer wells, and pressure relief devices, must be marked "liquid" or "vapor" to designate whether it communicates with liquid or vapor when the cargo tank is filled to the maximum permitted filling density. Provided the marking is readily visible, legible, durable to withstand transport conditions, and clearly associated with the corresponding inlet/outlet, the marking would satisfy the requirements of the HMR.

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


Shane Kelley
Standards and Rulemaking Division

Regulation Sections

Section Subject
178.337-9 Pressure relief devices, piping, valves, hoses, and fittings