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 #98-0251 ([National Tank Truck Carriers, Inc] [Mr. Clifford J. Harvison])

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

Interpretation Response Details

Response Publish Date:

Company Name: National Tank Truck Carriers, Inc

Individual Name: Mr. Clifford J. Harvison

Location State: VA Country: US

View the Interpretation Document

Response text:

OCT 8, 1998

 

Mr. Clifford J. Harvison                      Ref. No. 98-0251
President
National Tank Truck Carriers, Inc.
2200 Mill Road
Alexandria, VA 22314-4677

Dear Mr. Harvison:

This is in response to your letter dated August 25,1998, requesting clarification of repair and replacement requirements . for reclosing pressure relief valves on MC 306 cargo tank motor vehicles under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Your questions are answered as follows:

Q1. After August 31, 1998, we removed a reclosing pressure relief valve from a MC 306 cargo tank motor vehicle. The valve fails a "bench test" due to a faulty mechanical element within the valve. The mechanical element is repaired and the valve successfully passes the "bench test". May this valve be returned to service on an MC 306 cargo tank motor vehicle?

A1. Yes. The HMR permits the return of a refurbished (repaired) reclosing pressure relief valve to the cargo tank from which it was removed. However; if the repaired pressure relief valve no longer meets the performance requirements of the original specification (MC 306), the valve must be replaced. The replacement valve must meet the DOT 400-series pressure surge requirements under § 180.405(h) (2).

Q2. After August 31, 1998, we removed a reclosing pressure relief valve from a MC 306 cargo tank motor vehicle. The valve fails a "bench test" and the cause is determined to be the failure of a gasket, external to the valve assembly. We replace the gasket, and the valve successfully passes the "bench test". May this valve be returned to service on an MC 306 cargo tank motor vehicle?

A2. Yes. Regardless of whether the repair or refurbishment is internal or external to the valve assembly (for example, replacement of the valve seats, springs or gaskets), if the pressure relief valve meets the original specification performance criteria discussed in A1 above, it may be returned to service on the cargo tank motor vehicle from which it was removed.

I hope this satisfies your inquiry. If you need additional assistance, please do not hesitate to contact us.

Sincerely,

 

Hattie L. Mitchell, Chief
Regulatory Review and Reinvention
Office of Hazardous Material Standards

Regulation Sections

Section Subject
180.405 Qualification of cargo tanks
180.407 Requirements for test and inspection of specification cargo tanks