Spiral wound lining is a trenchless technology that uses a continuous plastic strip to form liners in gravity pipelines. This unique rehabilitation method originated in Australia and Japan during the 1980s. With four decades of installation history, the spiral wound method has been used on millions of metres of pipe across the globe. Like CIPP or slip lining, spiral wound liners provide a structural lining solution for fully deteriorated pipelines with minimal site disruption.
When it comes to Australia, spiral wound pipe technology is the most used product in the pipe renewal market. It has been used in the majority of pipes lined across Australia. Interflow has become synonymous with the technology, having installed more than 95 per cent of all spiral wound liners across the country.
Expanda was developed in Australia by Rib Loc, Interflow’s technology partner and released worldwide in 1990. Expanda has been installed throughout North America, Europe, and Asia. Interflow has been installing Expanda to renew deteriorated sewers, storm drains, and culverts in Australia since 1991 and in New Zealand since 2005. To date, Interflow has lined over 1.5 million metres of pipe with the product.
Expanda produces a PVC liner in intimate contact with the host pipe. It restores the structural integrity, reliability and flow efficiency of ageing sewer and gravity pipelines. Expanda can provide communities with an additional 50 years or more of life out of their pipelines.
There is no need for heating or temporary softening of Expanda, which is installed with a mechanical process. This approach increases the range of applications where structural sewer lining can be implemented. The PVC liner is rigid, providing a smooth circular bore to restore the hydraulic efficiency of the pipe. The material of the pipe does not restrict Expanda.
Rotaloc is a Rib Loc development for larger sized pipes, released in 2000. It has been used to renew sewer and stormwater pipelines worldwide. Interflow has lined over 25,000m of pipeline with Rotaloc throughout Australia and New Zealand. It can provide a structural liner for deteriorated pipelines. Rotaloc has been installed under difficult site conditions with minimal community disruption.
It is designed to bring back larger diameter deteriorated pipes and culverts to full service. There is no need to rely on the strength of the host pipe.
Rotaloc is installed by winding a continuous strip of interlocked PVC through the pipe using a custom winding machine. The machine moves through the pipe between access chambers or culvert openings and can adjust the diameter of the liner as it moves along the pipeline. It ensures the liner sits tightly against the host pipe, even if the diameter changes along its length. Once the liner is in place, the void between the liner and the host pipe can be filled with cementitious grout. This is typical in culvert applications to secure the liner in place.
Why have spiral wound pipes become so successful in this market? What are the main benefits to the installer and client?
First, spiral wound lining is made from a ribbed structure, giving it a high strength-to-weight ratio. That means less material is needed, making it a more cost-effective and sustainable solution. Such strength saw the Victorian Department of Transport introduce steel reinforced Rotaloc for rehabilitating three road culverts under the Monash Freeway. Rotaloc was strong enough to rehabilitate the three culverts without relying on the integrity of the host pipe.
Spiral wound lining can be installed while liquids flow through pipes without bypassing the flow. It can be deployed in numerous situations without disrupting people’s lives. The installation of the Rotaloc lining meant that there were no road closures on one of the busiest roadways in Melbourne. This saved time for the Department of Transport and headaches for tens of thousands of commuters daily.
The other challenge of the Monash Freeway culvert example is that each had different diameters. The Rotaloc solution worked seamlessly. At its most fundamental, the technique remains the same, regardless of the diameter of the pipe.
By locking strips of lining together, the installation process is entirely mechanical. There is no need for any curing or heating to prepare the lining for the pipe. Given the variable nature of pipelines, this is an enormous advantage. This was a suitable solution in Paraburdoo in remote Western Australia, where Interflow installed more than two kilometres of sewers with Expanda spiral wound liners.
When looking at any infrastructure project, a key component is managing the community impacted by the works. Spiral wound lining installations tend to have small site footprints and minimise disruptions to residents. An example of this occurred as part of the Albert Street sewer relining, which was part of the Cross River Rail Project in Brisbane. Interflow utilised its Expanda product to reline trunk sewer mains while only operating during limited windows at night in the middle of the Brisbane CBD.
Over the past 25 years, advances have extended spiral wound linings’ capabilities to larger sizes and greater load-carrying capacities. It has repeatedly been proven capable of renewing deteriorated sewers, storm drains and culverts. It can be utilised in applications where rehabilitation by lining would otherwise have been impossible.
Latest advances have seen many of the limitations of these liners overcome. They continue to extend the possibilities for structural rehabilitation of an ever-widening range of deteriorated conduit configurations under a broad range of conditions.
Investment is being made in further research and development. These results should see the possibilities extend further for trenchless structural pipeline rehabilitation.
As with past advances, development is taking place with the support of Australian and New Zealand water authorities. They have always encouraged such development. It represents a willingness to incorporate innovative solutions that can be seen to offer mutual benefits.