Lining techniques involve various systems including: cement mortar lining systems, epoxy spray lining systems, cure in place pipe lining, sliplining, swage & die draw lining, deformed pipe lining, spirally wound lining, live insertion and service pipe renovation methods.
Cement Mortar Lining Systems
Cement mortar lining is the application of a cement mortar (typically about 4mm thick) to the inside of pipelines to protect against corrosion.
Epoxy Spray Lining Systems
These are methods of lining pipes with a thin lining of resin (typically 1mm thick), which are sprayed onto the surface of a cleaned main. The aim of these techniques is to isolate the host pipe from the conveyed medium. There may be some potential for these techniques to be used to reinforce the structural capabilities of the host main.
Cure In Place Pipe Lining
Method of lining with a flexible tube impregnated with a thermosetting resin, which produces a pipe after resin cure. The lining may be set by the use of heat or UV light. Widely used in sewer applications less used in drinking water applications.
Techniques by which continuous or discreet pipes are inserted within existing pipes: examples include the pulling in of long lengths of PE pipes within water mains or the insertion of individual pipes within sewers. This is generally a low cost technique, which has the disadvantage of reduction of bore.
Swage & Die Draw Lining
Close-fit thermoplastic pipe lining systems, which are achieved by stretching a liner pipe by pulling it through one or more dies, to produce a temporary reduction in its diameter. This enables the liner pipe to enter the host pipe and then expand to give a tight fit against the inside of the host.
Close-fit thermoplastic pipe lining systems, which are achieved by pushing a liner pipe by pulling it through one or more sets of rollers, to produce a temporary reduction in its diameter. This enables the liner pipe to enter the host pipe. It is then expanded to give a tight fit against the inside of the host.
Deformed Pipe Lining
Compact Pipe- In this system PE pipe is factory extruded in a "C" shape and coiled onto a drum. This shape creates a clearance for the installation of the PE pipe into the host pipe. The folded pipe is then pressurized with steam, which rounds the liner, to form a close fit within the host pipe, sealing leakage and preventing corrosion. The system is designed for distribution and small trunk mains.
Subline- The Subline system involves the folding of thin walled polyethylene (PE) into a U shape to enable it to be installed within an existing pipe. The shape is held by a series of bands. This creates a clearance for the installation of the PE pipe into the host pipe, which is to be renovated. The folded pipe is then pressurized. This snaps the bands allowing the liner to revert back to its original shape, to form a close fit within the host pipe, sealing leakage and preventing corrosion. The system is designed for trunk mains.
Subcoil- In the Subcoil system PE pipe is factory folded into a "U" shape, which is held by a continuous sleeve. The product is then coiled onto a drum. The folding creates a reduction in diameter, which gives clearance for the installation of the liner into the host. The folded pipe is then cold pressurized which snaps the sleeve allowing the liner to revert back to its original shape, to form a close fit within the host pipe, sealing leakage and preventing corrosion. The system is designed for the renovation of distribution and small trunk mains.
Thermopipe- Thermopipe is a circular woven, high tensile polyester reinforced, polyethylene lining system. It is ideally suited for the renovation of water distribution mains and other pressurized piping systems. Supplied as a factory folded 'C' shaped liner, Thermopipe is semi-rigid when cool. Once pulled into the pipe, inflated and heated it becomes flexible and expands. This enables it to achieve a close fit to the host pipe, providing structural lining.
Spirally Wound Lining
In this system a plastic strip is spirally or helically wound to form a continuous lining. This is held in place initially by the expansion of the helix. A grout layer may be injected between the liner and the host pipe wall. The system is typically used in sewers.
Live Insertion is a method of sliplining a cast iron pipe with new PE whilst maintaining gas supplies to consumers. The old cast iron pipe is kept live during the insertion process. Once insertion is complete, the old main is again kept live to supply customers via the annular space. When operationally convenient, services can be transferred to the new PE which has also been 'gassed up'. Whilst primarily used on low pressure mains, the technique can also be used where the PE is tied into a new medium pressure system.