Typically High Density Polyethylene (HDPE) or Polypropylene (PP) are used as liners in steel pipes for natural gas distribution. However both the materials are prone to failures due to high temperatures and aggressive hydrocarbon environment.

Atofina - a producer of Polyamide 11 has recently conducted a research project to replace HDPE by a Polyamide 11 liner. This new liner is being tested in gas pipe mains in different American towns of Choctaux and Salt Lake City.

Polyamide 11 (PA11) piping - can allow gas distribution companies to operate plastic pipes at higher pressures and temperatures than possible with current plastic materials. With regulatory changes expected to permit the use of plastic piping at higher than the currently allowed 100 psig limit, GTI and Atofina Chemicals have performed comprehensive evaluations on PA11 (designed to operate at pressures between 100 to 300 psig) to validate its use at higher pressures. Additional evaluations are underway to address the effects of various climate and geographic environments.

The objective of this project was to characterize the material, physical and chemical properties of Polyamide 11 (PA11) in both laboratory and field environments. Additional research has focused on economic and institutional factors critical to the successful deployment of PA11 piping systems for the distribution of high-pressure natural gas in North America. Tests were also conducted on field-applied tools and techniques to shut off gas flow in PA11 pipe; PA11-compatible fittings; pipe coiling; and rapid crack propagation.

In today's utility environment, there is a growing interest on the part of those distributing natural gas to optimize the value of their assets, and to operate their distribution systems in a more flexible manner for enhanced energy service options. Gas companies could enhance their system operations throughput if lower cost plastic piping systems could be used at higher pressures.

At present, use of steel pipe is the only accepted alternative for the distribution of natural gas at pressures of 100 psi or more. With steel pipe, companies must use straight sticks of pipe and adjacent sections must be welded and/or mechanically coupled. This not only adds to the cost of installation, but also creates potential leak sources. The cost of corrosion protection and maintenance for steel mains can be as high as US$700 per mile pa. In comparison, PA11 offers most of the benefits of polyethylene (PE) plastics pipe while extending the range of operating pressures and temperatures. Because of its lower expected life-cycle cost, PA11 provides an ability to also capture new markets that otherwise would be lost to competing energy sources.