DOT reportable incident data review - natural gas transmission and gathering systems. Final report, 1985--1995

Our review of the DOT reportable incident data continues to show that external corrosion and third party damage still account for over 50% of the incidents for onshore pipeline systems. A majority of the external corrosion incidents resulted in a pipeline rupture. Five groups have been identified (e.g., farmers/landowners, pipeline operators, road crews, utility companies, and barges) that contribute to a majority of the third party incidents. These results may assist operators in identifying areas where further public education may be helpful in preventing future incidents. A review of the data showed that nearly 59% of the third party incidents occurred on pipe diameters less than 12 inches. Only 22 third party incidents have occurred on pipes with diameters greater than 24 inches. This suggests that large diameter pipes have less exposure to third party damage than is generally perceived. Nearly one-half of the reported fatalities and injuries have occurred in areas with limited access for the general public (e.g., compressor stations, metering facilities). Many of these fatalities and injuries are attributed to incorrect operations. These results may be helpful in developing scenario-based risk assessments within pipeline facilities. This report has shown that additional classification of the causes of failuremore » and further development of classification systems to better summarize the results are useful for analyzing the DOT reportable incident data. With enhanced classification systems, one can begin to make good use of the data for risk assessments although it is clear that a better breakdown of mileage data will be needed for proper normalization of the failure rates. Lastly, a broad overview of these data suggests that enhanced analysis of the data could lead to much greater efficiency in terms of the money spent to achieve safety objectives. Three particular issues discussed herein illustrate why this may be the case.« less