Peoples Natural Gas — Pipeline Safety Interpretation

Page 1February 24, 1972 Mr. Joseph A. Wager Measurement Superintendent Peoples Natural Gas 2223 Dodge Street Omaha, Nebraska, 68102 Dear Mr. Wager: This is in further reply to your letter of October 1, 1971, to Mr. Barry Sweedler of the National Transportation Safety Board, that was referred to this office for reply. With regard to your first question regarding Subparagraph 192.197(a)(1), which states: "A regulator capable of reducing distribution line pressure to pressures recommended for household appliances." Your interpretation is correct. This refers to a pressure regulator capable of reducing distribution line pressure (pounds per square inch) to pressures recommended for household appliances (inches of water column). With regard to your second question regarding Paragraph 192.199(g), which states: "Where installed at a district regulator station to protect a pipeline system from overpressuring, be designed and installed to prevent any single incident such as an explosion in a vault or damage by vehicle from affecting the operation of both the overpressure district regulator." protective device and You indicated that you are interested in knowing whether a modified regulator being used for commercial and industrial loads and delivering pressures of 5 to 25 pounds can be equipped with a monitor or a shut-off device in the same body. You interpret that a combination regulator and monitor in the same body will not meet the DOT specifications. Your interpretation is correct that the regulator you described would not meet our requirements if it were used as a district regulator. This would not exclude such a regulator from being used as a service regulator to an industrial or commercial customer as long as you comply with the requirements in Section 192.197. dal\192\199\72-02-24 1#

Page 2With regard to your series of questions regarding Section 192.623 which states: "No person may operate a low pressure distribution system at a pressure lower than the minimum pressure at which the safe and continuing operation of any connected and properly adjusted low pressure gas burning equipment can be assured." Your questions were: (1) Does this mean that devices must be installed where feeding gas into a low pressure distribution system so that the system cannot continue to operate if the pressure falls below a given amount? (2) Would this indicate that a low pressure distribution system being fed from one regulator station must have a station which protects against overpressure as well as underpressure? (3) Could one place the regulators in series using one as a monitor, or could one interpret this as meaning that another regulator or two regulators must be placed in parallel to protect against underpressure? All the methods that you described would be appropriate under certain operating conditions. It is the operator's responsibility to assure that whatever method that is selected will meet the requirements of Section 192.623 for the operating conditions of the particular system. We trust that this will answer your particular questions. If you need further assistance, please let me know. Sincerely, /signed/ Joseph C. Caldwell Acting Director Office of Pipeline Safety dal\192\199\72-02-24 2#