Seismic risk assessment for oil and gas pipelines - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 683

Permanent ground displacement

Subsurface soil characterization for soil restraint

Pipeline strain capacity

Pipeline strain associated with ground displacement

Increasing uncertainty

25.1 Qualitative depiction of relative uncertainty in key vulnerability
assessment parameters.

and thermal exposure from the ignition of a gas cloud. For oil pipelines, the
effects of oil release typically include thermal radiation from pool fi res,
property damage from inundation with oil, and environmental contamina-
tion. The assessment of consequences involves many uncertain parameters,
such as those listed below:

• size of the pipe opening;

• location of the pipe opening around the pipe circumference;

• availability of ignition source;

• duration of leakage;

• vapor cloud dispersion parameters (e.g., wind speed, wind direction, and

terrain roughness);

• number and location of persons near the pipe opening;

• number and location of structures near the pipe opening.

The measure of risk is defi ned both in terms of vulnerability and conse-
quences (e.g., 0.01% chance per year for a fatality from thermal radiation).
This risk measure is reviewed for acceptability and to identify possible
actions to reduce unacceptable risk. This is normally an iterative process as
the potential reduction in risk is measured by re-evaluating changes pro-
duced by the identifi ed actions on the likelihood of a hazard occurrence,
the consequences of the hazard, and combined risk.

25.4 Types of seismic hazard
In addition to the loadings under operational conditions, potential loads on
buried pipelines from seismically induced hazards are of importance to
assessing the performance of pipeline systems.