Assessing and Implementing New Materials for Replacement and Rehabilitation of Piping Systems

Polyamide 11 and 12 (PA11 and 12), thermoplastic materials, are excellent alternatives to steel pipe in high-pressure applications up to 250 psig. It is easier to install than steel and eliminates the need for costly long-term corrosion control measures.

Two 2010 field trials coordinated by GTI—at Energy West in Montana and Atmos Energy in Mississippi—demonstrated the benefits of PA12 piping for two very different applications. At Energy West, PA12 piping was installed to run new high-pressure gas lines in order to provide gas service to a new area. Several 1” PA12 gas services were also installed using electrofusion fittings.

The Atmos Energy installation was designed to demonstrate the benefits of using PA12 piping for the rehabilitation of older high-pressure steel lines. These installations helped to advance the adoption of plastic piping systems by validating the use of PA12 at higher operating pressures (increasing 125 psi to 250 psig) and helping to change federal code (49 CFR Part 192) to allow the permanent use of PA12 piping systems.

Under sponsorship of OTD, GTI is also looking at ways to rehabilitate transmission, distribution and gathering lines with composite materials and cured-in-place liners. Research has provided operators with a product selection guide to help determine the best option for a specific application. The guide includes currently available reinforced thermoplastic pipe (RTP) products and compares composite/RTP piping products with each other as well as with other steel replacement options.GTI has also collected data to help pipeline operators select a composite pipeline repair system based on its ability to restore serviceability of damaged pipe. Based on testing full-scale sections of pipes with composites and evaluating the long-term performance of their associated adhesives, their use as allowed by CFR 29 Part 192 codes is justified.