The publication of a new ASTM International standard for nylon 12 (PA12) line pipe will extend and support its use in industrial pressure pipe applications like crude oil and gas gathering networks.
The standard was developed by ASTM's plastic piping systems committee to set requirements and test methods for PA12 materials, pipe and fittings.
The use of PA12, a specialty type of nylon with exceptional strength and durability, as pressure pipe for natural gas distribution networks was approved by the Pipeline and Hazardous Materials Safety Administration (PHMSA), which is part of the U.S. Department of Transportation, for regulated applications in 2019.
The standard was published as F3524 and took about a year to develop from start to finish.
PA12 resin has been produced commercially since the early 1960s. The material has been extensively used in automotive fuel systems and as the pressure barrier in flexible pipes used in offshore oil and gas production.
Now a standard covers practices and specifications for pressurized crude oil and gas gathering and industrial piping.
"The requirements of the applications are similar. The design engineer will apply appropriate design and service factors to suit the specific application," according to Jim Mason, secretary of the ASTM International's subcommittee F17.68 on energy piping systems and an active developer of the new ASTM standard.
Mason also is the founder of Mason Materials Development LLC, a consulting firm serving the plastics and engineered materials industries. PA12 pipe contributes to improved health, safety and environmental performance compared with steel pipes, Mason said in an email.
"PA12 is not subject to the corrosion mechanisms that affect steels," he explained. "This eliminates leaks and ruptures caused by corrosion and the attendant health, safety and environmental consequences."
PA12 also has a benefit over high density polyethylene when it comes to pipe. PA12 pipes can have smaller diameters and thinner walls, so less material is used.
"The long-term hydrostatic strength of PA12 is twice that of HDPE at temperatures up to 180° F," Mason said. "Higher strength means that thinner walls can be used to get the same strength. Thinner walls make the pipe [inner diameter] larger, increasing flow capacity, so engineers can often use smaller, nominal-diameter pipe to achieve the same flow rates as with larger-diameter pipe that has a thicker wall."
Another standard, ASTM F2785, which also addresses use of PA12, was initially published in 2009 and has been updated frequently since then, Mason said.
In response to some of the changes, Baraboo, Wis.-based Teel Plastics Inc. extruded the PA12 gas pipe used in the first installation under PHMSA's 2019 so-called Mega Rule, which allowed the innovative PA12 pipe to be installed in the U.S. without a special permit.
Teel provided more than 2,800 feet of 200 psi PA12 pipe for a municipal gas distribution project in Henderson, Ky.
Henderson officials said ease of installation gave nylon pipe the edge over steel pipe because the project was slated for an industrial section of the city. To minimize disruption, the pipe was installed under driveways and roads using horizontal drilling. Crews pulled the pipe through the bored holes and then fused the sections together.
Mason said PA12 also is considered an "excellent choice" as a pull-through liner material for steel pipe rehabilitation.
"Future applications may include biogas transport and hydrogen gas transport," Mason said.
In addition to the applications addressed by the new standard and the gas distribution application, Mason said PA12 is used in spoolable reinforced thermoplastic pipes standardized in API 15S, offshore platform flexible pipes standardized in API 17J and thermoplastic composite pipes standardized in DNV-ST-F-119.