U.S. Department of the Army — Pipeline Safety Interpretation

Page 1Mr. J. E. Pate, Jr. Chief, Permit Branch Galveston District, Corps of Engineers U.S. Department of the Army P.O. Box 1229 Galveston, TX 77553 Attention: SWGCO, Permit Application 11432 Dear Mr. Pate: Your letter of July 28, 1976, requests comment on the information provided by Transcontinental Gas Pipe Line Corporation (Transco) in their permit application number 11432. This application proposes to install an addition to a pipeline system to transport natural gas from existing wells in the Gulf od Mexico, Galveston, and High Island areas. All pipelines subject to the jurisdiction of this Office must comply with the requirements of 49 CFR Part 192, "Transportation of Natural and Other Gas by Pipeline," or 49 CFR Part 195, "Transportation of Liquids by Pipeline." Amendments 192-27 and 195-11 were recently issued to these minimum Federal safety standards to provide more comprehensive standards for offshore facilities. Sections 192.327 for gas pipelines and 195.248 for liquid pipelines require that all pipe installed in any offshore location under water less than 12 feet deep must have a minimum cover of 36 inches in soil or 18 inches in consolidated rock between the top of the pipe and the natural bottom. Sections 192.319 and 195.246 require offshore pipe in water at least 12 feet deep but not more than 200 feet deep to be installed so that the top of the pipe is below the natural bottom unless it is supported by stanchions, held in place by anchors or heavy concrete coating, or protected by an equivalent means. These are minimum requirements intended to be used in normal situations and do not necessarily provide the protection needed from special hazards that may be encountered in shipping lanes or anchorages. Part 192, Section 192.103, General, requires that pipe must be designed with sufficient wall thickness, or must be installed with adequate protection, to withstand anticipated external pressures and loads that will be imposed on the pipe after installation. Part 195, Section 195.110, External loads, requires that anticipated external loads (e.g., earthquakes, vibration, thermal expansion and contraction) must be provided for in designing a pipeline system. DB C:\WP51\INTERPRT\192\327\76-10-14 1#

Page 2the information provided in your letter does not include the characteristics of the sea bottom nor any description of external stresses from ship anchors or other causes that might be anticipated for the pipelines in this area. The regulations require adequate protection for the pipeline; however, they do not specify the type of protection. Additional depth of burial is one way of providing that protection if the additional depth is sufficient for the anticipated stresses or loads. It is hoped that these comments will be helpful in your consideration of the Transco permit. Thank you for you interest in pipeline safety. Sincerely, Cesar DeLeon Acting Director Office of Pipeline Safety Operations DB C:\WP51\INTERPRT\192\327\76-10-14 2#