Seismic vulnerability assessment and design of pipelines

Pipelines are vulnerable to earthquake shaking (ground motion) and permanent ground deformation (PGD) resulting from liquefaction landslide and fault movement. Pipe performance during an earthquake depends on four parameters: ruggedness, resistance to bending, joint flexibility, and joint restraint. Pipe materials are rated in this article for each of these parameters to help utilities select the appropriate pipe for the job. New pipelines installed in regions with high seismic activity should use continuous or restrained-joint pipe, including steel pipe with welded joints, high-density polyethylene pipe with fused joints, or ductile-iron pipe with restrained joints. These guidelines are applicable to pipelines installed in both competent soils (i.e., those capable of providing competent foundation performance) and soils subject to PGD. Additional mitigation measures are recommended for critical pipelines. In regions with moderate seismic activity, pipe with segmented joints such as ductile iron and polyvinyl chloride, can be used in competent soils, but in soils subject to PGD continuous or restrained-joint pipe similar to that used in areas of high seismicity should be used. For existing systems, replacement of existing pipe is not cost-effective based on earthquake vulnerability alone, unless the pipe is critical for maintaining system operation. Vulnerable pipe should be replaced over the long term, with prioritization based on both seismic vulnerability and other asset management parameters. In the short term, system owners should focus on system control and emergency response mitigation approaches.