While Fusible PVC (F-PVC) commands a substantial share of the North American trenchless pipeline rehabilitation market, until now it has not been attempted in Australia, despite the promise of significant cost benefits to asset owners and trenchless pipeline installers.
Iplex National Technical Services Manager Rodger Connolly said “There are technical barriers to conventional PVC being used in trenchless applications.
“Firstly, PVC compound formulations are unstable at the very high temperatures required to weld strings of pipe. This has resulted in unreliable weld quality and secondly, the processes for welding pipe were based on incompatible polyethylene fusion techniques.
“The people at Underground Solutions discovered ways of overcoming both of these issues and patented the solutions.”
Without discounting the significant cost benefits of using the standard PVC range of couplings, valves and service connections, the largest savings provided by F-PVC result from the thinner walls of F-PVC compared to polyethylene pipes.
“This usually results in pipe diameters at least one size smaller in PVC. For example, a 560 mm diameter F-PVC pipe is hydraulically equivalent to a 630 mm diameter polyethylene pipe of the same pressure class.
“This means a 20 per cent smaller hole needs to be bored and when the costs associated with spoil disposal, drilling mud and time are accounted for, F-PVC will win out almost every time on these large diameter jobs,” said Mr Connolly.
The higher tensile strength and lower elasticity of PVC pipes permit longer shot lengths to be pulled with a horizontal directional drill rig than has been traditionally possible in polyethylene.
Iplex’s trenchless specialist Peter Klouda said “We’re not suggesting that F-PVC will be the solution in every instance, but it opens up a whole new range of trenchless opportunities.
It expands our suite of trenchless pipe products that includes Meyer polymer concrete jacking pipe, Restrain threaded joint drainage pipe and of course, our high density polyethylene pipe in diameters up to 2 m.”
As urban density increases and the redevelopment of brown-field former service station and car park sites becomes increasingly common in cities, problems are encountered where potable water pipes pass through contaminated soil.
In 2008 the American Water Works Association’s Research Foundation published findings indicating that PVC pipe was impermeable by petrol. This fact has assisted F-PVC to become one of the dominant pipe materials used in brown-field site redevelopment.