The use of Swagelining, a trenchless technology for lining new or existing pressure pipes with polyethylene (PE), has been quietly growing in North America for the last three years.
The Swagelining process was developed by BG Plc (formerly British Gas) as a rehabilitation process for its own gas lines. Since then the technology has been used to renew or protect more than 600 miles of pressure pipe ranging from 3 to 36 inches in diameter. These applications include water, forced sewer, gas, oil, and a wide range of industrial production lines all over the world.
The Swagelining process uses polyethylene pipe which has an outside diameter slightly larger than the inside diameter of the pipe. During installation, the PE pipe is pulled through a die to reduce its outside diameter. This reduction allows the PE to be pulled through the host pipe with a winch. When the pulling force has been disconnected, the PE returns to its original diameter. As it relaxes, the PE presses against the inside of the host pipe, eliminating all annular space.
The PE materials used in the process are manufactured to ISO, AGA, ASTM, and API standards, and have known physical properties and an established service life. No curing or field chemistry is involved. BG Plc has carried out extensive research to ensure that the long-term stability of the PE is not affected by the die compression and winching. ISO/TC138-SC4 Notch Test Group tests also show no measurable loss of performance as a result of the process.
Individual joints of PE pipe are butt-fused together at the job site to form a jointless pipe slightly longer than the section of original pipe being lined. When PE pipe is butt-fused, the molecules of the two pipe sections flow together and become one. As a result, the finished pipe is truly jointless. Typically, pulls are about 500 feet long, but single pulls up to 1500 feet have been made.
"Swagelining is a process with a solid track record," said Syd Parkes, Commercial Manager, BG Technology, a part of BG Plc. "Swagelining was developed by BG for its own use, and it has served extremely well in that capacity for many years. However, in recent years other key industries have discovered Swagelinings usefulness and employed it in a wide range of applications."
Conoco and BP-Amoco have used the process to line new, high-pressure water injection pipelines used in North Sea oil fields. In those situations, the pipelines must withstand extremely corrosive water at internal pressures of over 4,000 psi and remain maintenance free for at least 25 years.
The Swagelining technology is licensed to contractors who have now carried the process into Europe, the Middle East, North and South America, and China. BG Technology maintains an office in Houston to serve clients and contractor licensees in the United States.
Jim Hopwood, manager of Swagelining operations in North America, is working on seven projects in the United States. Most inquiries have been about forced sewers and potable water mains. Swagelining rehabilitation projects have been completed in California, Colorado, New Jersey, New Mexico, New York, and Texas in the United States, as well as some projects in Canada.
Hopwood said that he had made a success of licensing Pipebursting, a pipeline replacement process owned by BG. Pipebursting is a trenchless process which is used to replace or up-size existing pipelines. It has been used to replace well over 1,000,000 feet of pipeline in the U.S. during the last two years.
