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Other methods

There are a number of different lining methods that can be used to rehabilitate pipes. Some of them are mostly used for sewage and wastewater. When rehabilitation of a potable pipe is needed, the options become limited. The most widely used method is the cement mortar lining, but it is not the only technique available for potable water pipe rehabilitation. In order to fully understand the advantages of the Aqua-Pipe cured-in-place liner, it is necessary to compare those methods.

Here is a description of the available methods to help you make an informed decision

Cement mortar lining is the application of a cement mortar (typically about 4mm thick) to the inside of pipelines to protect against corrosion.

Sprayed cement mortar lining is a proven technique for the renovation of deteriorated cast iron, ductile iron and steel pipelines. The first step is the cleaning of the pipe in order to remove all the corrosion debris prior to lining. The liner can then be applied using different methods depending on the size of the pipe. For smaller pipe diameters, the mortar is applied by a robot and is pumped directly to a rapidly revolving dispensing head from which it is thrown by centrifugal force onto the pipe wall. For larger diameters, the mortar is applied centrifugally as with small diameter lining, but the equipment used is very different. The mixed mortar is dispensed into a speed buggy, which travels back and forth from the access hole to the intermediate loader.

The popularity of the cement mortar lining is based on the number of years this method has been available and the savings that can be made when compared to the open-cut method used to replace pipes. Although it is well known and can be an option to rehabilitate pipes, it is not a lasting solution than can resolve future pipe bursting or leaking. Ultimately, it is a method that lacks durability and that cannot be used when there is deterioration of the exterior pipe.

These are methods of lining pipes with a thin lining of resin (typically 1mm thick), which is 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.

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 technique, which has the disadvantage of reduction of bore.

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.

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 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.

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 Mains 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.” While primarily used on low pressure mains, the technique can also be used where the PE is to be tied into a new medium pressure system.

Some of these methods are mostly used for sewage and wastewater. When rehabilitation of a potable pipe is needed, the options become limited. The most widely used method is the cement mortar lining, but it is not the only technique available for potable water pipe rehabilitation. In order to fully understand the advantages of the Aqua-Pipe^® cured-in-place liner, it is necessary to compare both methods.