Trenchless Rehabilitation on Pressure Pipes
Fold and form pipe liners are premanufactured liners which are inserted into pipes for rehabilitation processes. The folded form, usually an H or C shape, allows for easier insertion into pipes. Fold and form liners are custom made to fit the inside diameter of the pipe. The outer diameter of the liner is approx. 5% lesser than the bore diameter of the pipe. Once inserted, heat and pressure are applied to the liner such that it expands and forms a close fit with the host pipeline. Once the process is complete, the ends are trimmed off. The connections are restored using CCTV camera and robotic cutters. The materials used for these liners are environment friendly and do not pose any risk even when used for rehabilitating pipes carrying potable water.
Plastic pipe has been around for decades and has been one of the dominant piping materials. The upstream of a fold-and-form pipeliner production line is identical to most plastic pipe extrusion lines. Differences are in the downstream. A normal plastic pipe needs to be in circular shape and cut into short sections, Fold-and-form pipeliners are intentionally flattened or folded. The pipeliners are then coiled on reels into much longer sections, normally several hundred linear meters. Polyvinyl chloride (PVC) has been selected as a preferred fold-and-form pipeliner material for more than 25 years.
Fold-and-Form Pipeliners Provide Superior Quality Assurance
The industry consensus ASTM product standards (ASTM F1871 and ASTM F1504) were established in the late 1990s. The ability to confirm compliance with the quality and physical properties of a fold-and-form pipeliner before and after installation permitted the creation of such product standards. The pipeliner is manufactured in environmentally controlled facilities where the design properties are established under ASTM required QA/QC protocols.
Besides the raw material standard, Fold-and-form pipeliners have to comply with their product standards, ASTM F1871 and ASTM F1504. The product standard defines the requirements of materials, size, wall thickness and marking. Furthermore, these ASTM standards cover quality assurance/control (QA/QC) test methods and requirements.
Fold-and-Form Pipeliners Are Environmentally Benign
The environmental impact during and after pipeliner installation has become a rising concern in the pipe rehabilitation industry. Thermoformed pipeliners have no noxious or caustic chemicals and do not contain volatile organic compounds (VOCs), such as styrene, that are human and environmental health concerns. In fact, the compounds used within thermoformed pipeliners are all recognized as safe for use in potable water applications. Current research at the University of Virginia stated that pre-manufactured fold-and-form pipeliners “are not expected to have any significant adverse environmental impact” and “are environmentally benign.”
Application
For trenchless rehabilitation on gravity pipeline.