Risk Assessment Techniques in the Pipeline Industry

During the past two decades, emphasis on pipeline safety has shifted from response to prevention of accidents. Preventive actions have included greater levels of inspection, involvement of the public through communications, and prospective analysis of the dangers presented by pipelines. Pipeline companies also began to use various risk assessment techniques, including hazard and operability (HAZOP) analysis, fault tree analysis, scenario-based analysis, and indexing methods. Most analyses focus on specific factors affecting the probability of pipeline failure (e.g., internal corrosion, external corrosion, pipeline loading) or on the consequences of rupture (such as heat intensity, thermal impact radius, depth of cover). Some of these analyses focus on specific pipeline system components, while a few attempt to take component interdependencies into account. Some of the more commonly used techniques are described below.

The pipeline risk assessment and management approaches that have been published to date, regardless of the methodology used to obtain the probabilities and consequences of processes and events leading to risk, emphasize the calculation of a risk number (i.e., a mathematical product of probability and consequence). Although this calculation allows a quantitative comparison of the effect of different factors on pipeline safety, it is not adequate to define risk to the public.

Recently, the U.S. Department of Transportation’s Office of Pipeline Safety (OPS) implemented a new regulatory approach—the Integrity Management Program—that establishes new testing, repair, and mitigation requirements for transmission pipelines and requires pipeline companies to use a risk-based approach for pipeline safety. Under the program, liquid and natural gas pipeline operators, as a first step, will be required to perform risk assessments on each of their pipeline segments in high-consequence areas. Inspections will be performed by the use of in-line inspection tools, analysis of operating and maintenance records, and direct examination of pipe in selected areas. Risk criteria have been considered in other countries, including societal risk due to land use near pipelines (IGE 2001; Committee for the Prevention of Disasters 1999).

Source :

http://www.nap.edu/read/11046/chapter/10