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Interpretation Response #PI-74-0133

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

Interpretation Response Details

Response Publish Date: 08-13-1974
Company Name: Tennessee Public Service Commission    Individual Name: Mr. John Searcy
Location state: TN    Country: US

View the Interpretation Document

Request text:

Tennessee Public Service Commission
Cordell Hull Building
Nashville, Tennessee 37219

July 26, 1974

Mr. Joseph C. Caldwell, Director
Office of Pipeline Safety
Department of Transportation
2100 Second Street, SW
Washington, D.C. 20590

Dear Mr. Caldwell:

Both 192.197(a) and (b) intend the same end result, which is prevention of unsafe appliance pressure. (b) must be complied with when (a) is not. However, in (a), the conditions under which unsafe appliance pressure must be prevented are normal operating conditions, and in (b), the condition is regulator failure.

This appears to be inconsistent, since compliance with (a) does not provide for regulator failure, yet is the first of two alternatives " prevent a pressure that would cause the unsafe operation of any...gas utilization equipment."

Is it correct that the intent of 192.197(a) is to also provide for regulator failure?


John Searcy
Engineering Division

Response text:

Mr. John Searcy
Tennessee Public Service Commission
Cordell Hull Building
Nashville, TN 37219

Dear Mr. Searcy:

Thank you for your letter of July 26, 1974, asking whether 49 CFR 192.197 (a) provides for protection against overpressure due to failure of a regulator.

Sections 192.197(a) and (b) protect against unsafe operation of gas utilization equipment due to overpressuring by a distribution system. Paragraph (a) sets forth criteria for a service regulator to provide this protection. Under paragraph (b), where a regulator does not meet that criteria, the operator must install suitable devices to protect against overpressure when the regulator fails. The problem of providing protection against overpressure due to failure of a regulator which meets the criteria of paragraph (a) is not addressed by the regulation.

We trust our response is helpful to you.


Joseph C. Caldwell
Office of Pipeline Safety

Regulation Sections

Section Subject
§ 192.197 Control of the pressure of gas delivered from high-pressure distribution systems