Pipelines transport a wide range of toxic and flammable gases and liquids in close proximity to population centers. The most familiar examples are natural gas transmission lines that can be 3 feet in diameter and operate at pressures of 1000 pounds per square inch. Lines carrying gasoline, jet fuel, crude oil and liquefied petroleum gas (LPG) can also pose risks to individuals and as well as[W1] structures. It is less well known that pipelines also carry other hazardous chemicals such ammonia and carbon dioxide. In contrast to fixed facilities, the distance to potential populated areas can be much smaller for a pipeline, so that the precision and accuracy of the analysis technique can have a large effect on the projected risk. In addition, a pipeline risk assessment needs to address the probability of a breach at various locations along the route. Specialized methods are required to properly quantify the risk and consequences of a pipeline rupture, whether it is due to an accident or malicious intent. The specific hazards to be addressed can vary widely depending on the substance being transported. For example, the rupture of a natural gas transmission line can cause a dangerous radiant heat flux at substantial distances. Due to its high vapor pressure, a gasoline spill can represent an even greater hazard because flammable vapor can move beyond the margins of the liquid to encounter potential sources of ignition. In other instances, the liquid itself can also migrate significant distances beyond the point of the release. Because it disperses as a heavierthan- air gas, a release of LPG from a pipeline rupture poses both a vapor cloud explosion and radiant heat hazard. This paper describes a general methodology to address both individual and population-risk from pipelines and provides examples of the consequences and risks of pipeline failures for specific flammable and toxic materials.
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