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Interpretation Response #13-0233 ([Began Tank Truck] [Mr. Bob Berry])

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

Interpretation Response Details

Response Publish Date:

Company Name: Began Tank Truck

Individual Name: Mr. Bob Berry

Location State: OR Country: US

View the Interpretation Document

Response text:

May 28, 2014

Mr. Bob Berry
President
Began Tank Truck
7605 NE 21st Avenue
Portland, OR 97211

Ref. No.: 13-0233

Dear Mr. Berry:

This is in response to your email dated November 26, 2013, requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to external visual inspection and testing of pressure relief valves on DOT specification cargo tanks.  

As provided in § 180.407(d)(3), all reclosing pressure relief valves must be externally inspected for any corrosion or damage which might prevent safe operation. Additionally, all reclosing pressure relief valves on cargo tanks carrying lading corrosive to the valve must be removed from the cargo tank for inspection and testing. Finally, each reclosing pressure relief valve required to be removed and tested must open at no less than the required set pressure and no more than 110 percent of the required set pressure, and must reseat to a leak-tight condition at no less than 90 percent of the start-to-discharge pressure or the pressure prescribed for the applicable cargo tank specification.

In your letter you describe a scenario in which two cargo tank pressure relief valves with a set pressure of 30 psig are tested in accordance with § 180.407(d)(3).  The first relief valve opens at 30 psig and reseats at 90 percent of the start-to-discharge pressure or 27 psig.  The second relief valve opens at 33 psig or 110 percent of the set pressure and reseats at 27 psig.  You ask if the second valve may remain in service or if it would need to reseat at no less than 29.7 psig or 90 percent of the start-to-discharge pressure.

The answer is yes, the second valve may remain in service.  In a final rule issued under Docket No. PHMSA-2006-25910 (HM-218E; 74 FR 16135) PHMSA revised
§ 180.407(d)(3).  In making the revision, the text “open at the required set pressure and reseat to a leak-tight condition at 90 percent of the set-to-discharge pressure” was replaced with “open at no less than the required set pressure and no more than 110 percent of the required set pressure, and must reseat to a leak-tight condition at no less than 90 percent of the start-to-discharge pressure.”  As provided in the preamble to the final rule, and based on comments provided by the National Propane Gas Association, the intent was to replace the term “open” with the phrase “start-to-discharge” and maintain the phrase “set-to-discharge” for the reseating pressure.  This was not correctly implemented in the regulatory text.  Therefore, the

second valve in the scenario described could remain in service as it reseated at 27 psig or 90 percent of the 30 psig set-to-discharge pressure.

We have received a petition for rulemaking concerning this topic and it will be addressed in a future rulemaking.

I trust this information is helpful.  If you have further questions, please do not hesitate to contact this office.

Sincerely,

Shane C. Kelley
Acting International Standards Coordinator
Standards and Rulemaking Division

180.407(d)(3)

Regulation Sections

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