Interpretation Response #PI-19-0008
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Mr. Karl H. Baker
Public Utilities Supervisor of Technical Analysis
Connecticut Public Utilities Regulatory Authority
10 Franklin Square
New Britain, CT 06051
Dear Mr. Baker:
In a July 24, 2019, letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA), the Gas Pipeline Safety Unit (GPSU) of the State of Connecticut Public Utilities Regulatory Authority requested an interpretation of the 49 CFR Part 192 requirements for maximum allowable operating pressure (MAOP) for gas distribution pipelines during maintenance operations.
You stated that PHMSA's interpretation letter dated April 21, 2015, sent to Mr. Christopher LeBlanc of Northern Utilities, Inc., doing business as Unitil, discussed MAOP under normal and emergency operations; however, it was not clear to you whether activities during maintenance are included in this interpretation. Specifically, you asked that "since the maintenance requirements contained in 49 CFR 192.739(a)(3) require operators to set overpressure protective devices at pressures consistent with the pressure limits of 49 CFR 192.201(a), is it permissible for an operator to exceed the MAOP when setting the overpressure protective device at a pressure limiting station?"
The overpressure protective device, pressure limiting or regulator station that limits overpressure beyond the MAOP must be isolated from the system prior to any testing of buildup and set points. Operators can exceed the MAOP during maintenance of the isolated overpressure protection equipment as specified under § 192.739(a) consistent with the pressure limits of § 192.201(a), if the MAOP limits are met during a system maintenance and the pipeline meets all Subpart D requirements of 49 CFR Part 192. The overpressure protective device (pressure limiting or regulator station) that limits overpressure beyond the MAOP must be isolated from the system prior to any testing.
Maintenance operations that may result in overpressure conditions are only allowed for the time interval required under § 192.739(a) to activate the overpressure protection device and are not meant for long term or frequently-occurring normal operating or maintenance conditions.
If we can be of further assistance, please contact Tewabe Asebe at 202-366-5523.
John A. Gale
Director, Office of Standards
|§ 192.739||Pressure limiting and regulating stations: Inspection and testing|