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 #18-0125

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

Interpretation Response Details

Response Publish Date:

Company Name: Truck Trailer Manufacturers Association

Individual Name: John Freiler

Location State: VA Country: US

View the Interpretation Document

Response text:

April 16, 2019

John Freiler
Truck Trailer Manufacturers Association
7001 Heritage Village Plaza, Suite 220
Gainesville, VA  20155

Reference No. 18-0125

Dear Mr. Freiler:

This letter is in response to your October 5, 2018, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the design of MC-331 cargo tanks. Specifically, you ask about the requirements for shear sections on valves.

We have paraphrased and answered your questions as follows:

Q1. You ask if § 178.337-10(f) applies to valves located within a recessed well that meet the accident damage protection requirements on top of an MC-331 cargo tank.

A1. The answer is yes.  Section 178.337-10(f) still applies to valves located on the top of an MC‑331 cargo tank that meet the requirements for accident damage protection.

Q2. You ask if a ball valve without a shear section may be used for liquid and vapor connections within a recessed well on top of an MC-331 cargo tank.

A2. The answer is no.  A shear section is still required. The ball valve and recessed well do not except the cargo tank from the requirements for shear sections on valves.

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


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

Regulation Sections

Section Subject
178.337-10 Accident damage protection