Concentric Pipe Reduction Systems
Concentric Pipe Reduction Systems utilise the elastic nature of plastic pipes to form a tight fit lining system within a host pipe. The original external diameter of the liner is the same as the internal diameter of the host pipe, and to install the liner, the liner pipe has its diameter reduced to a size that will allow it to be pulled or pushed into the host pipe. However, unlike sliplining this is not the final liner position. Once in place the liner is allowed to expand to its original diameter thereby pushing it against the host pipe inner wall forming a ‘Close Fit’ lining with the host pipe, minimising diameter losses of the host pipe due to the lining operation. Both standard thickness plastic pipes (usually PE) and thinner walled liner pipe can be used depending on the desired structural requirements of the relined pipe. Thicker liners can add to the structural integrity of the host pipe if its deterioration is such that this is a requirement of the liner design. Thinner walled pipes can be used to provide a semi-structural lining capable of sealing minor leaks and other defects such as which may be particularly applicable to water mains.
There are two types of reduction option – tension reduction by pulling the liner through a reduction die (e.g. Swage lining) and external compression (e.g. Rolldown) whereby the liner is pushed through a set of rollers. Swage lining utilises a specially designed diameter reduction die through which the liner pipe is pulled by winch into the host pipe reducing the diameter to the necessary degree. . Once the reduced diameter liner pipe is in place in the host pipe the tension is released allowing the pipe to revert to its original diameter thereby lining the pipe. The compression method entails reducing the diameter of the liner pipe by pushing it through a set of rollers. The liner which retains the reduced diameter is then pulled through the host pipe by winch cable. Once it is in position internal pressure is applied to the liner to revert it to its original size thereby forming a tight fit against the host pipe inner wall.