Connecticut Public Utilities Regulatory Authority — Pipeline Safety Interpretation

Page 1U.S. Department ofTransportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue SE Washington DC 20590 OCT 2 2 2019 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. The Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations (49 CFR Parts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the specific facts presented by the person requesting the clarification. Interpretations do not create legally-enforceable rights or obligations and are provided to help the public understand how to comply with the regulations.#

Page 22 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. Ifwe can be of further assistance, please contact Tewabe Asebe at 202-366-5523. Sincerely, Jo . Gale Oirector, Office of Standards and Rulemaking The Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety provides written clarifications of the Regulations (49 CPR Parts 190-199) in the form of interpretation letters. These letters reflect the agency's current application of the regulations to the specific facts presented by the person requesting the clarification. Interpretations do not create legally-enforceable rights or obligations and are provided to help the public understand how to comply with the regulations.#

Page 3STATE OF CONNECTICUT PUBLIC UTILITIES REGULATORY AUTHORITY July 24, 2019 Mr. John Gale Director, Standards and Rulemaking Division Office of Pipeline Safety (PHP-30) Pipeline and Hazardous Materials Safety Administration U.S. Department of Transportation 1200 New Jersey Avenue SE Washington, DC. 20590 Dear Mr. Gale, The Gas Pipeline Safety Unit (GPSU) of the State of Connecticut Public Utilities Regulatory Authority seeks clarification on exceeding the maximum allowable operating pressure (MAOP) during maintenance operations. Your interpretation letter dated April 21, 2015, sent to Mr. Christopher LeBlanc of Unitil Corporation, clearly discusses MAOP under normal and emergency operations; however, it is not clear whether maintenance operations are included in this interpretation. Therefore, the GPSU requests an answer to the following question: Since the maintenance requirements contained in 49 CFR 192.739(a)(3) require operators to set to 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? Thank you for your consideration in this matter. Please do not hesitate to contact me at 860-827-2661 or by email at karl.baker@ct.gov if there are any questions or if you require any additional information. Sincerely, Karl H. Baker Public Utilities Supervisor of Technical Analysis 10 Franklin Square, New Britain, CT 06051 An Equal Opportunity Employer www.ct.gov/pura#