Likelihood, causes, and consequences of focused leakage and rupture of U.S. natural gas transmission pipelines

• Failure probabilities of natural gas transmission pipelines are analyzed.
• Possible effects of pipeline age, wall thickness, and pipeline diameter on failure probability are examined.
• Consequences of significant incidents, including property damage and the human impact are studied.

The safety of pipelines that transport energy (particularly natural gas transmission pipelines) has become an important and controversial issue with the general public. This study provides strong evidence that the US transmission pipeline network is safer than many believe. Published estimates of risk of pipeline failure are typically in the range 1.2 × 10−4 to 6.1 × 10−4 per km yr. Risk of pipeline failure differs significantly with diameter, with fatality rates of 4.6 × 10−6 per km yr for larger pipelines and 2.4 × 10−6 per km yr for smaller transmission pipelines. The average injury rate was 1.9 × 10−5 per km yr for smaller pipelines, compared to 5.9 × 10−6 per km yr for larger transmission pipelines. The failure rate for large diameter transmission pipelines is larger, the older the pipeline segment. The joint impact of pipeline diameter and wall thickness on failure rate reveals that increased wall thickness is effective in mitigating risks. Overall, natural gas transmission pipelines have significantly lower fatality rates than do truck or railway transport of hazardous materials. For larger transmission pipelines, the estimated rates for serious injuries (3.0 × 10−6 per km yr) and fatalities (6.3 × 10−7 per km yr) for the public, are at a level generally considered acceptable by most countries.