Replacement/Upgrades Remain Priority For Gas Distribution Market

February 2013, Vol. 68 No. 2

A recently released report Gas Distribution Infrastructure: Pipeline Replacement and Upgrades prepared for The American Gas Foundation by Yardley Associates provides insight into the need for Local Distribution Companies (LDCs) to replace or upgrade existing pipeline infrastructure.

As noted in the report, natural gas provides 25 percent of the nation’s primary energy, serving more than 71 million customers and is used to generate 21 percent of U.S. electricity supplies. Competitive pricing, environmental benefits and supportive public policies contribute to the widespread use of natural gas for heating, cooking, industrial process applications, and growing electric generation and transportation needs. Of course, this would not have been possible without public confidence in the safety and reliability of interstate transmission and local distribution pipeline delivery networks.

The report also points out that the overwhelming majority of the nation’s natural gas is produced within North America and transported to U.S. market areas by more than 300,000 miles of large-diameter, high-pressure pipelines. Local distribution companies (LDCs) deliver gas supply within market areas to customers using 1.2 million miles of smaller diameter, low-pressure mains and 880,000 miles of customer -service lines that deliver gas from a street connection to the customer’s meter.

One challenge facing LDCs, regulators and other industry stakeholders is the impact of leak-prone infrastructure installed using materials that are susceptible to corrosion or other material failure.

Prior to 1940, the primary materials used for distribution pipe were wrought and cast iron. Just as the 1940s and 1950s saw a transition to steel materials, which were relied upon exclusively for a few decades, the 1970s brought a transition from steel to plastic facilities, except for large-diameter installations that continued to rely on steel.

Although plastic pipe materials have evolved over time and LDCs rely predominantly on medium- and high-density PE materials, a number of iron, steel and certain categories of plastic pipe pose distinct concerns as they age.

As indicated in Table 1, more than 112,000 miles of distribution mains in service at the end of 2011 are constructed of materials and techniques that are the most susceptible to corrosion and leaks, requiring eventual replacement.