Annual Gas Distribution Survey

Annual Gas Distribution Survey
February 2011, Vol. 66 No. 2

Plastic pipe
Polyethylene (PE) has been widely used in fuel gas distribution piping systems since the late 1950s. Today, polyethylene accounts for 97 percent of all new gas distribution piping installed each year.

These tough, durable piping products offer tremendous advantages to the gas piping engineer for the design and installation of a highly cost-effective, reliable and safe fuel gas distribution system. Highly flexible and light-weight, PE piping systems are chemical and corrosion resistant thereby reducing the need for cathodic protection of the underground piping infrastructure. The heat fusion method of joining these systems provides the potential of leak-free system performance. A full range of diameters from ½-inch CTS to 24-inch IPS is available in a variety of wall thicknesses or SDR's.

According to the Plastics Pipes Institute, a new thermoplastic piping material has been introduced to the fuel gas distribution industry. Polyamide (PA) piping systems offer a new range of performance capability. The PA piping systems possess a higher hydrostatic stress rating than the traditional PE piping systems, and, as such, provide a perfect complement for higher pressure operational needs. Like the PE piping systems, the PA systems are available in a broad array of sizes and with a full complement of fittings. Similarly, the PA piping systems are joined using heat fusion methods which provide, once again, for the potential for leak-free system performance.

While polyamide piping products have been used in various energy-related applications for over three decades they have only recently been introduced to the fuel gas distribution industry. Today, 4-inch IPS SDR 11 Polyamide 11 is the only plastic pipe that is approved for use in fuel gas distribution at pressures up to and including 200 psi by the Department of Transportation. The Plastics Pipe Institute says this illustrates the potential use of PA piping systems as a durable, corrosion-free, chemical-resistant and leak-free alternative in the operating ranges of steel pipe.

Pipeline incident prevention
According to the PHMSA, the vast majority of America’s pipeline network is underground making pipelines vulnerable to “dig-ins” by third-party excavators. While excavation damage is 100 percent preventable, it remains a leading cause of pipeline incidents involving fatalities and injuries. Three-quarters of all serious consequences from pipeline failures relate to distribution systems and more than one-third of these failures are caused by excavation damage.