You are here

Interpretation Response #PI-99-0100

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

Interpretation Response Details

Response Publish Date: 02-08-1999
Company Name: California Public Utilities Commission    Individual Name: Mr. Mahendra Jhala
Location state: CA    Country: US

View the Interpretation Document

Response text:


U.S. Department of Transportation
Mr. Mahendra Jhala
Chief, Utilities Safety Branch
Consumer Services Division
California Public Utilities Commission
505 Van Ness Avenue, 2nd Floor
San Francisco, CA 94102

Dear Mr. Jhala:

This responds to your request for an official interpretation of 49 CFR 192.731, 192.739, and 192.743. You asked if these sections apply to compressor station relief devices that relieve natural gas in equipment and systems associated with operation of the compressor, such as fuel gas lines and instrument gas lines.

We previously said that these sections apply to all gas relief devices in compressor stations. Only relief devices on non-gas carrying equipment are exempt. Later on, Zach Barrett of the Western Region had several questions about this interpretation. So we are passing along our answers, which amplify our original statement.

Question: Does the interpretation mean any vessel or piping in a compressor station that contains natural gas for whatever purpose is jurisdictional?

Answer: At a minimum, the interpretation applies to gas relief devices on any vessel or piping in the compressor station that is used in the transportation of gas. It's unclear whether § 192.731 was intended to cover devices on vessels or piping that are unrelated to gas transportation by pipeline.

Question: Does the gas in the aforementioned vessels or piping have to be in transportation, i.e., passing through the vessel or piping en route to the consumer before the vessel or piping is considered jurisdictional?

Answer: Subpart M, and consequently § 192.731, applies to the maintenance of pipeline facilities, i.e, things used in gas transportation by pipeline. It doesn't matter whether the vessel or piping actually carries gas in transportation. Although there may be a question whether a fuel gas line carries gas in transportation, it's certainly used in transportation and, therefore, a pipeline facility.

Question: Would blanket gas injected over the top of a liquid such as glycol in a tank (with a relief device) make the tank and relief device subject to the regulations?

Answer: Yes, if the tank is used in gas transportation by pipeline. Please let me know if you would like any further assistance.


Richard D. Huriaux
Regulations Manager

Dear Mr. Kent:

This responds to your letter of November 10, 1976, in which you ask two questions regarding the Federal gas pipeline safety standards in 49 CFR Part 192.

First, you ask whether the requirements of Sections 192.731, 192.739, and 192.743 concerning the maintenance of pressure relief devices and limiting stations apply to devices and stations which are not part of a "pipeline" as that term is defined in Section 192.3. As examples, you refer to devices and regulators which are used in gas compressor stations for purposes other than to relieve or limit gas pressure, such as devices or regulators on compressed air or fuel systems.

The word "pressure" in Sections 192.731, 192.739, and 192.743 restricts the applicability of those sections to devices or stations which serve to relieve or limit gas pressure. The sections do not apply to devices or regulators which are part of non-gas carrying equipment inside gas compressor stations.

This interpretation is based on the relationship between the words "pressure" and "gas" occurring throughout Part 192 and in particular in the requirements of Section 192.192 for installation of pressure control devices. Since under Section 192.3 the term "pipeline" encompasses all the gas carrying parts of an operator's systems, the pressure relief devices and limiting stations subject to Sections 192.731, 192.739, and 192.743 are those on a pipeline.

Secondly, you ask whether, in an aquifer storage field, gas pipelines running from the gas injection system to certain water removal wells are transmission lines. Under 40 CFR 192.3, the term "transmission line" means a pipeline other than a gathering line that... "transports gas within a storage field." This definition is broad enough to apply to any pipeline carrying gas within the boundaries of a storage field. Therefore, since the lines in question are clearly not gathering lines, they are classified as transmission lines under Part 192.


Cesar DeLeon
Acting Director
Office of Pipeline Safety Operations

Regulation Sections

Section Subject
§ 192.743 Pressure limiting and regulating stations: Capacity of relief devices