Interpretation Response #98-0116 ([Fort Vale] [Mr. Don Kilgore])

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

Interpretation Response Details

Response Publish Date: 10/14/1998

Company Name: Fort Vale

Individual Name: Mr. Don Kilgore

Location State: TX Country: US

View the Interpretation Document

Response text:

OCT 14, 1998

Mr. Don Kilgore                      Ref. No: 98-0116
Sales Manager
Fort Vale
8560 Katy Freeway, Suite 160
Houston, Texas 77024

Dear Mr. Kilgore:

This is in response to your letter dated June 1, 1998, requesting clarification on reclosing pressure relief valves on MC 307 cargo tanks under § 180.405 (h) of the Hazardous Materials Regulations (HMR.; 49 CFR Parts 171-180).

A "properly functioning" reclosing pressure relief valve is one that functions according to the specification in the Hlv:1R. There is a difference between repair, refurbishment and replacement. Internal parts such as o-rings or valve seats may be replaced. If external threads are galled or stripped to an extent that the pressure relief valve can no longer meet the performance requirements in the original specification (e.g., MC 307), the valve must be replaced. Until August 31, 1998, a replaced valve could be in conformance either with the requirements for the pressure relief valve at the time the specification became superceded (see § 178.342), or with the requirements for the pressure relief valve for the DOT 407 cargo tank motor vehicle (see § 178.347). After August 31, 1998, replacement valves must meet the requirements in § 180.405 (h)(2). A frangible and/or fusible cap may be used in conjunction with the reclosing pressure relief valve after August 31, 1998, as long as the original air flow requirements for the specification are met.

In response to your question on calculating air flow, the pressure relief device system must limit the internal pressure of the cargo tank to 130% of the MA WP as per the original specification requirements. The pressure relief device must be rated at a pressure no less than 130% of the MA WP and no more than the test pressure of the cargo tank.

I hope this satisfies your request.

Sincerely,

Delmer F. Billings
Chief, Standards Development
Office of Hazardous Materials Standards

Regulation Sections