Pipeline Safety Interpretation PI-78-0109

Page 1PI-78-0109 November 27, 1978 Mr. Richard Sanders Chief, Pipeline Safety Mississippi Public Service Commission Walter Sitters State Office Building P.O. Box 1174 Jackson, Mississippi 39205 Dear Mr. Sanders: We apologize for the delay in answering your letter of August 1, 1978, regarding Section 192.199(h). With your letter, you included a sketch which shows a schematic of a regulator installation, including valves on the inlet and outlet of a regulator and a bypass valve. A relief valve is shown on the piping at the outlet of the regulator with valve ahead of it which is marked "locked." You asked: 1. "Should an inspector cite this system under Part 192.199(h)?" 2. "Should an inspector cite this system under any other portion of the code?" 3. "Should an inspector accept this as meeting the law - and if he liked, recommend to the operator that locking the valve would be good practice?" Since Section 192.199 is in Subpart D - Design, it only applies to facilities that were readied for service after March 12, 1971, or replaced, relocated, or otherwise changed after November 12, 1970. If the facilities illustrated by your diagram were built or changed prior to these dates, Section 192.199(h) would not apply. Assuming this to be so, and the relief valve does not have sufficient capacity as you illustrate, then, should the system be over pressured, Section 192.619(b) or Sec 192.621(b) could be applied. If your diagram describes facilities built or changed after the above date(s), Section 192.199(h) would apply to the regulator installation. However, paragraph only applies to gas line valves installed between the system to be protected and Relieving or limiting device. It does not apply to valves in bypass lines because such valves do not make the relieving or limiting device inoperative. With regard to your third question, the Materials Transportation Bureau normally does not recommend pipeline safety practices that are not required by the regulations. We trust that this response will enable you to resolve these items of concern. Sincerely, Cesar DeLeon Associate Director for Pipeline Safety Regulation Materials Transportation Bureau#

Page 2Mississippi Public Service Commission P.O. Box 1174 Jackson, Mississippi 39205 August 1, 1978 Dear Mr. Pollen: A question has risen as to whether or not operators should be cited under Part 192.199 (h). Please note attachment "A" that I have prepared to enlighten you as to some of the findings our personnel have experienced during inspections of operators. It is my contention that the by-pass valve should be locked, since it would allow pressures to exceed the maximum allowable operating pressure of the downstream distribution system. I am not sure whether or not 192.199, Part (h), would cover or any other portion of the code covers such a situation. Your assistance in answering the questions that I have prepared on attachment "A" would be of assistance to our operations in the State of Mississippi. Respectfully yours, Richard Sanders Chief, Pipeline Safety#