Pitch Fibre Pipes – Maddington

Project Summary Sheet

Customer: Water Corporation

Location: Maddington, WA

Delivered: May 2016

The Challenge

Pitch fibre pipes never achieved widespread use in Australia. Developed in the late 1800s, they were made from a matrix of wood fibre and coal tar pitch. With these materials being readily available, they were a cheap alternative, mainly used for ducting, although small quantities were used to convey sewage.

For the Water Corporation of Western Australia deterioration of pitch fibre pipes installed in the mid-1900s meant difficulties beyond those that normally apply to deteriorated sewers in built up areas.

Digging and replacing was not an option because of their location in a built up area and issues with the disposal of material classified as hazardous.

Pipebursting was not favoured because of the need for excavation of launch and winch pits as well as issues with fragmenting of the hazardous coal tar material.

Deformation in the pipes meant that some lining methods used with other types of sewers would not be possible.

The Solution

The Water Corporation and Interflow worked together to determine a practical solution. Interflow’s term contract with the Water Corporation (Perth Reticulation Sewer Relining 2015/16) gave the incentive to work on an innovative application.

First the unique properties of pitch fibre pipes needed to be investigated and understood. The pipe is flexible but becomes brittle with age. Interflow and the Water Corporation found that, while the pipe could be re-rounded, it reverted to its previous deformed shape in a short period of time.

The solution developed was to re-round the pipe using a specially made tool, then quickly install a spiral wound PVC SPR™ EX – Expanda Pipe liner while the pitch fibre pipe remained in its circular shape.

The Project

Rehabilitation commenced with excavation of a small collapsed section of pipe and using this excavation to insert the re-rounding tool.

The SPR™ EX – Expanda Pipe liner, installed in a rigid state, instantly provided sufficient stiffness to leave a permanent, strong, circular shape.

Applying this methodology meant overcoming numerous challenges due to the location of the works and the need for flow bypass. Interflow worked with the Water Corporation ensuring conditions were suitable for the complex, timecritical procedure.

Conclusion

The success of the project was due to the partnership between the Water Corporation and Interflow, which resulted from incentive for innovation provided by a long term contract.

Interflow is committed to offering its customers optimum solutions of the highest value for pipeline rehabilitation.