What are pressure limiting and regulating stations? See §192.739?

Inspection of pressure limiting and regulating stations is required by “§192.739  Pressure limiting and regulating stations:  Inspection and  testing.”  These inspections must be conducted at intervals not exceeding 15 months but at least once each calendar year.

An examination of the enforcement letters over the past years shows that this is a very active code section for various types of action, from warning letters to actual violations.  Inspections may not have been conducted in a timely manner, procedures may be inadequate or missing, or stations may not have been inspected at all.

Operators must be diligent in identifying all such stations.  However they must also be cautious in not including additional stations that are not on regulated piping, such as end-use equipment.

The following interpretation from 2004 addresses the types of stations that must be inspected under Part 192 regulations.  Interestingly enough, while there is no definition of what these stations consist of, this interpretation states “the definition of “pressure limiting station” or “pressure regulatory station” as these terms are defined in the ASME B31.8 standard.”

These definitions are displayed with the interpretation.

From ASME B31.8, 2003 edition, current at the time of the interpretation: (Copyright © ASME International)

803.323 Pressure regulating station consists of equipment installed for automatically reducing and regulating the pressure in the downstream pipeline or main to which it is connected. Included are piping and auxiliary devices such as valves, control instruments, control lines, the enclosure, and ventilation equipment.

803.324 Pressure limiting station consists of equipment that under abnormal conditions will act to reduce, restrict, or shut off the supply of gas flowing into a system to prevent the gas pressure from exceeding a predetermined value. While normal pressure conditions prevail, the pressure limiting station may exercise some degree of control of the flow of the gas or may remain in the wide open position. Included in the station are piping and auxiliary devices, such as valves, control instruments, control lines, the enclosure, and ventilating equipment, installed in accordance with the pertinent requirements of this Code.

 

Interpretation 192.739  19
January 22, 2004

U.S. Department of Transportation
Research and Special Programs Administration
400 Seventh Street, S.W.
Washington, D.C 20590

Mr. Martin C. Schwoeble
Pipeline Integrity Compliance Specialist
Dominion Transmission, Inc.
445 West Main Street
Clarksburg, WV 26301

Dear Mr. Schwoeble:

This is in response to your letter of November 3, 2003, in which you request an interpretation of the Federal gas pipeline safety regulation at 49 CFR 192.739, Pressure Limiting and Regulating Stations: Inspections and Testing. The question arises from small regulators on the Dominion Transmission, Inc. (DTI) system that provides protection for operating, or end-use, equipment. These types of regulators are installed by the manufacturer of the equipment and are not intended to be inspectible by pipeline operators.

Section 192.701, Scope, notes the Subpart M “prescribes minimum requirements for maintenance of pipeline facilities.” Section 192.739 must be read in cognizance of this scope statement. It is clear that § 192.739 is intended to address inspection and testing of pressure limiting and regulating stations that are necessary to maintain safe pressures on the pipeline facility, not on end-use equipment.
This is consistent with the June 28, 1988, interpretation letter cited in your letter. In that interpretation, we note that a regulator subject to § 192.739 would have to fall within the definition of “pressure limiting station” or “pressure regulatory station” as these terms are defined in the ASME B31.8 standard. Under these definitions, it is clear that any regulator serving a downstream piping is a pressure regulating station and is subject to inspection and testing in accordance with § 192.739. Conversely, a regulator that is NOT intended to protect a downstream piping, but rather serves only to protect end-use equipment, such as a compressor, would not be subject to § 192.739.

If you have any further questions about the pipeline safety regulations, please contact me at (202) 366-4565.

Sincerely,

Richard D. Huriaux, P.E.
Manager, Regulations
Office of Pipeline Safety

*****************************************************
Dominion Transmission inc.
445 West main Street
Clarksburg, WV 26301

Richard D. Huriaux
Department Of Transportation, Office Of Pipeline Safety
400 7th Street
Southwest, Room 7128
Washington D.C., 20590
November 3, 2003

RE: Interpretation Request

Dear Mr. Huriaux,

This letter’s purpose is to ask for an interpretation of CFR Part 192.739, “Pressure Limiting and Regulating Stations: Inspections and Testing” for Dominion Transmission Incorporated (DTI).
DTI is currently inspecting numerous small regulators downstream of the first initial regulators (first or second main pressure cut) on fuel gas lines that feed various types of equipment such as main compressor units, pipeline heaters and dehydration systems, etc. Typically, these types of fuel regulators consist of 1″ or smaller. They are not intended to protect a transmission pipelines maximum operating pressure. Their sole purpose is to provide protection for the operating equipment. These types of small regulators are usually installed by the manufacturer of the equipment and would require major piping changes to conduct an inspection of them.

Part 192.739 states that “Each pressure limiting station, relief device (except rupture discs), and pressure regulating station and its equipment must be subjected…” to inspection annually, not to exceed 15 months. What is the proper definition of a pressure limiting or regulating “station”? An interpretation found in WinDOT, dated 06/28/88, states that a pressure regulating station is any regulator serving a downstream “main”. This is not the case regarding the aforementioned equipment examples.

It is DTI’s stance that the jurisdictional transition point should be the first valve downstream of the last regulator and/or relief valve associated with the first pressure cut from the transmission pipeline, including any regulator within the by-pass. If a measurement device used for consumption exists beyond this point, then the measurement device becomes the jurisdictional transition point. All downstream pressure limiting and regulating devices from this jurisdictional transition point would then be exempt from Part 192.739.

DTI has a vast amount of these types of small fuel line regulators throughout our operating system and the inspection of them is a burdensome task that is costly and has been found to be of no benefit. DTI thereby requests that the Office of Pipeline Safety please grant these types of small fuel regulators be exempt from Part 192.739.
We appreciate any input you may have regarding this matter. If you have any questions, please feel free to contact me via the following phone numbers:

Office: xxx
Cell Phone: xxx

Respectfully,

Martin C. Schwoeble
DTI Pipeline Integrity Compliance Specialist

All this and more including new interpretations never before published, in WinDOT, The Pipeline Safety Encyclopedia.

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