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 Assessing the Fitness for Service of Distribution Pipelines 

Natural gas is a clean burning and abundant energy source that cleanly fuels the life of 177 million Americans nationwide.  Natural gas is delivered through pipeline systems of varying size and material type to customers for residential, commercial and industrial use. Natural gas pipelines, which transport approximately one-fourth of the energy consumed in the United States, are an essential part of the nation’s infrastructure. The distribution piping systems that comprise the natural gas infrastructure of this country have evolved primarily over the past century and continue to improve to help ensure that natural gas is delivered safely, reliably and efficiently.  Natural gas utilities continually maintain, monitor and assess system performance to help ensure safe pipeline operations.

The term “fit for service” indicates that a pipeline facility performs as expected and carries an acceptable safety and reliability risk in its continued use. All companies are required to adhere to federal codes that address pipeline design, construction and maintenance activities to help ensure the safe and reliable delivery of natural gas to customers. Furthermore, most states, some municipal governments and the gas companies themselves require operating standards to be met that correspond with, and often exceed, federal codes.  Over time, these governmental actions and standards have led to a steady decline in leaks and reportable incidents on the distribution pipeline system.

Operators continually work to identify and address pipeline facilities that need improvements. Natural gas utilities conduct engineering studies to define, prioritize and develop mitigation strategies to help reduce risks.  In light of pipeline incidents that have occurred in recent years, companies are redoubling their focus to further improve data analysis.

The 2006 Pipeline Safety Act required the development of the distribution integrity management rule (DIMP), a far-reaching performance-based regulation that builds upon the infrastructure safety improvements previously achieved. DIMP,  effective in August of 2011, requires operators to develop and implement a plan to formally document data gathering, analysis, risk ranking and mitigation activities associated with fitness for service studies. In conjunction with existing regulations, DIMP will help formalize and document distribution pipeline systems’ fitness for service and will help improve the safety and reliability of the nation’s natural gas distribution systems.

May 2012


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