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Feasibility Study of Replacement Procedures and Earthquake Perforrmance of Gas Transmission Pipelines

T.D.O'Rourke, M.C.Palmer

NCEER-94-0012 | 5/25/1994 | 188 pages

About the Report:

TOC: The table of contents is provided.

Keywords: Buried Pipelines, Welded Steel Pipelines, Gas Transmission Systems, Welds, Wave Propagation Effects, Seismic Risk Assessment, Southern California Gas Company, Replacement Procedures, and Earthquake Engineering.

Abstract: A general procedure for evaluating the relative risks from earthquake hazards to steel pipelines is developed. The procedure accounts for the influence of traveling ground waves, surface faulting, landslides, and soil liquefaction. The procedure utilizes information, acquired primarily through reconnaissance studies, on regional geology, groundwater conditions, aerial photos, and site-specific soil borings obtained principally through public agencies. Two transmission pipelines in Southern California, Lines 121 and 123, were selected for a feasibility study. Both lines were constructed in 1930, and therefore represent older, more vulnerable portions of the system which are joined with oxy-acetylene welds. Emphasis in this work is placed on characterizing the geotechnical and earthquake hazards to these pipelines, especially the potential for surface faulting and large ground deformation caused by liquefaction. A general replacement procedure is recommended. It involves a three-step process in which a system planning assessment is made, followed by a repair record cost assessment, with a risk assessment completing the evaluation. At each stage in the evaluation, a decision to replace or retain is made.