Pipeline Safety Interpretation PI-78-0108

Page 1PI-78-0108 November 09, 1978 Mr. Roy R. Die Exxon Pipeline Company Post Office Box 2220 Houston, Texas 77001 Dear Mr. Die: Thank you for your October 13, 1978, letter to Secretary Adams notifying us of your intent to place in service your pipelines from South Pass Block 93A and Mississippi Canyon Block 268. Section 195.6 does not require notice in the case of multi-phase gas and oil flow because, as stated in Section 195.1(b)(1), Part 195 does not apply to a commodity transported in a gaseous state. However, as your letter indicates, since the pipelines will be carrying natural gas and crude oil they will be subject to 49 CFR Part 192 as well as Part 195. Thus, they must comply with the applicable requirements of both Parts and, in the event of conflict, the more stringent requirement of either Part. Sincerely, Cesar De Leon Associate Director for Pipeline Safety Regulation Materials Transportation Bureau#

Page 2October 13, 1978 Exxon Pipeline Company Post Office Box 2220 Houston, Texas 77001 Mr. Brock Adams Secretary, Department of Transportation Washington, D. C. 20590 This letter is Exxon Pipeline Company's notice of its intention to include natural gas as a transported commodity along with crude oil in the captioned offshore pipelines located in the Gulf of Mexico. The purpose of this notification is compliance with the requirements of DOT section 195.6, Transportation of Certain Commodities. These pipelines were recently constructed in conformance with Title 49 CFR Part 195, Minimum Federal Safety Standards for Liquid Lines. During construction it was learned that natural gas transportation in multiphase flow would be required from both South Pass Blk. 93A and Mississippi Canyon Blk. 268. These offshore lines are in federal waters and do not impact in a safety sense on the general public, or to a significant degree on Exxon employees. The most pertinent aspect of the operation of these pipelines is the potential impact on the environment. Thus, the containment, repair, and clean up of the crude oil constituent of the multiphase mixtures should be the principle concern of both the DOT and the EPA. In addition, even though the projected (gas/oil) ratios are high the pipelines are extensions of an extensive existing crude oil pipeline system and from a practical sense they should be operated and managed as liquid pipelines. Based on the above considerations, these multiphase pipelines will be operated and reported in accordance with Title 49 CFR Part 195. Operation of the South Pass line is scheduled to begin about November 1, 1978 and the Mississippi Canyon line should begin operation in April, 1979. As the design, II-testing and operating conditions for these lines meet the most stringent regulatory requirements of both the gas and liquid regulations, we assume the 90 day notice set forth in Paragraph 195.6(a) does not apply. Roy Die#