James Mason, John Chen and Gregory O’Brien
Development in Plastic Materials # 2004 Milan
This paper presents an overview of the first high pressure polyamide-11 (PA-11) natural gas plastic pipe field installations with operating pressures of 150 to 200 psi. We describe the layout and operating pressures, the local soil and environment conditions, as well as the installation methods employed to complete the trials. Installation experiences from trial installations in Choctaux, Louisiana; Nashville, Tennessee; and Salt Lake City, Utah; are described. We also review results of studies completed in conjunction with the Gas Technology Institute on the effects of coiling and straightening of PA-11 piping as well as the validation testing of fittings, valves and other components to confirm their ability to operate at higher pressures. As part of the field trials, pipe samples were evaluated after removal from the trial installations after 12 and 24 months to confirm the durability of a PA-11 piping system over time. The testing protocol is discussed, along with the results and conclusions to date. Finally, the application of PA-11 piping to replace steel piping in contaminated soils will be discussed. Due to the higher resistance of PA-11 to hydrocarbons, this use of PA-11 pipe could eliminate corrosion concerns that come with installing metal sections in current lower pressure plastic gas pipe installations.
