Earthquake Protection for Pipelines

Dear Joe:
Is any extra support or safety equipment used to protect the gas pipeline in places like California (where there are lots of earthquakes)?

Angelo E. Polanco,
Connecticut Natural Gas

Answer: Earthquakes don’t occur only in the West; they can strike any location (e.g., Virginia and Alabama). California has a state law that requires natural gas operators to prepare for – and minimize damage to -pipelines from earthquakes.

For example, Pacific Gas and Electric (PG&E) has an earthquake fault crossings program that compiles geological survey data and analyzes/identifies areas susceptible to seismic activity. These studies provide critical information on how best to implement mitigation measures to improve safety at each fault crossing.

Mitigation measures may include modifying trench designs and/or adjustments, stabilizing unstable ground, making pipes more resilient, using larger pipe supports, replacing cast iron and steel pipe with polyethylene pipe, using rupture control valves, installing earthquake (seismic) actuated gas shut-off valves, and using remote controlled valves. Also, seismic vulnerability may be offset with flexible couplings or expansion joints and above ground fault crossings.

Tip: Part 192 represents the Minimum Federal Safety Standards, but each U.S. state may have additional regulations above those of the Federal requirements.

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