Tennessee Public Service Commission — Pipeline Safety Interpretation

Page 1January 30, 1976 Mr. John Searcy Engineering Division Tennessee Public Service Commission Cordell Hull Building Nashville, Tennessee 37219 Dear Mr. Searcy: This replies to your letter of July 28, 1975, requesting interpretations for various sections of 49 CFR 192. Question 1: Is any remedial action implied in §192.739 and §192.749? If so, would such action be subject to sections 192.195 thru 192.203 and 192.183 thru 192.189, since this would involve a change after November 12, 1970? Reply: Sections 192.739 and 192.749 govern the maintenance of pressure limiting station relief devices and pressure regulating stations and vaults used in the transportation of gas. Remedial action as appropriate, is implicit in the requirements of these sections. Any specific component which is replaced, relocated, or changed as a result of inspections or tests made under sections 192.739 and 192.749 must comply with all applicable requirements of 49 CFR 192, including those to which you refer. Question 2: Does the phrase "distribution system," relative to §192.741(a) and the Office of Pipeline Safety Operations' (OPSO) interpretation presented in Advisory Bulletin 74-11, apply to both high and low pressure distribution systems as defined in Part 192? Reply: Yes. Question 3: Define "district regulator" as used in §192.741(a). Reply: The term "district regulator" is not used in §192.741(a). we presume you are referring to the term "district pressure regulating station," which serves as a controlled source of gas supply to a district, or area, within a gas distribution system. Question 4: Does §192.741(a) mean that systems which are each served individually by one regulator, such as distribution systems 1, 2, and 3 as identified in Diagram A, would require telemetering or recording devices or that such recording devices would only be required on dal\192\739\76-01-30 1#

Page 2systems served by more than one regulator, such as distribution system 4 identified on Diagram A? Reply: Section 192.741(a) is not applicable to distribution systems served by only one district pressure regulating station, as is the case for distribution systems 1, 2, and 3 in Diagram A. However, telemetering or recording pressure gauges may be necessary for compliance with §192.741(b), which applies to a distribution system supplied by a single district pressure regulating station. As indicated by our letter to you, dated November 6, 1974, §192.741(a) only applies where two or more district pressure regulating stations supply a distribution system which is common to all such sources of supply, such as distribution system 4 in Diagram A. Question 5: You ask us to indicate on two diagrams (A and B) where telemetering or recording devices would be required. Diagram A shows three district, labeled 1, 2, and 3, each supplied by only one district pressure regulating station, and two district pressure regulating stations supplying a distribution system, labeled 4, which is integrally interconnected downstream from the two district pressure regulating stations. In distribution system 4, both stations are located on the same side of the geometric perimeter of the distribution system. Diagram B has essentially the same configuration as A, except that districts 1 and 4 have been combined so that the resulting integrated system is supplied by two district pressure regulating stations - one at a geometrically opposite extremity from the other. Reply: In accordance with §192.741(a), telemetering or recording gauges are required for distribution system 4 of Diagram A and distribution system 1/4 of Diagram B. Systems 1, 2, and 3 of Diagram A and 2 and 3 of Diagram B are supplied by single district pressure regulating stations and may need telemetering or recording gauges in accordance with the criteria of §192.741(b). Sincerely, Cesar DeLeon Acting Director Office of Pipeline Safety Operations dal\192\739\76-01-30 2#

Page 3July 28, 1975 Mr. Cesar DeLeon Department of Transportation Office of Pipeline Safety 2100 2nd Street, SW Washington, D.C. 20590 Dear Mr. DeLeon: 1. 2a. b. c. d. 192.739 requires inspections of pressure limiting and regulating stations, and 192.749 requires inspections of vaults of 200 cubic feet or more. These inspections are to determine that certain items, including capacities, pressure settings, and ventilation, are adequate and proper. However, if inadequate capacities or ventilation, or improper pressure settings are found, no remedial action is specifically required except in 192.743(c), which applies only to relief devices. Is any remedial action implied in 192.739 and 192.749 and, if so, is it a correct interpretation that such action would be subject to the requirements of 192.195 through 192.203 and 192.183 through 192.189, since this would involve a change after November 12, 1970? Relative to 192.741(a), and the related interpretation appearing in Advisory Bulletin 74- 11, is it a correct interpretation that the word "distribution system" covers both high and low pressure distribution systems as defined in Part 192? Please define "district regulator" as used in 192.741(a). Does 192.741(a) mean that separate sub-systems within a common major distribution system, each served individually by one regulator, such as sub-systems 1, 2, and 3 in the attached diagram, would require telemetering or recording devices; or, that such separate sub-systems would require telemetering or recording only when served by more than one regulator, such as sub-system 4 in the attached diagram? Please indicate on attached Diagram A where 192.741(a) would require telemetering or recording devices. dal\192\739\76-01-30 3#

Page 4e. If sub-systems 1 and 4 were combined and the combination supplied by 2 regulators, one at each extreme of the system, as shown in Attachment B, please indicate where 192.741(a) would require telemetering or recording devices. Sincerely, John Searcy Engineering Division Attachments dal\192\739\76-01-30 4#