Published On 15/09/2020
A research project to examine the long-term performance of plastic pipes used to supply the nation’s drinking water has finally unearthed its performance secrets.
In an UKWIR and Severn Trent Water funded project, Severn Trent Water has exhumed the plastic pipes installed in special testbeds at two of its Midlands’ pumping stations in the early 1980s and 1990s.
Up until then the pipes and joints have been kept live and “in-service” and, latterly, subjected to specific chemical and mechanical testing to determine changes in performance – in particular to predict when the pipes degrade and fail i.e. they begin to leak or burst.
That information is crucial as around 95,000km of the UK’s drinking water pipe network is made of polyethylene (PE) and is currently used for 90% of new water mains being laid.
The most recent project – to exhume some sections of the pipes to assess their condition and combine that with analysis of their performance – has now been completed.
That’s revealed that PE pipes with similar characteristics to the ones exhumed will last for longer than the current 50-year design life – and more recent high-pressure pipes such as PE100 could have a useable life of as much as 160 years.
Additionally, the project has confirmed that installation issues cause most of the joint failures on PE pipe, underlining the need to monitor and improve workmanship.
Jo Claronino, Technical Lead at Severn Trent Water, said: “The exhumation of these pipes from our testbeds has all the excitement of an archaeological dig and the discoveries we have made are ground-breaking for the water industry.
“It’s thanks to the foresight made by engineers 40 years ago that today’s water industry engineers have a valuable asset in its own right – robust data. The hope is that this can be used to create a national database of companies’ analysis showing the life expectancy of water supply networks across the UK and Ireland.”
Rebecca Haylock, UKWIR Project Manager, said: “A lot of work has been done to limit the impacts of supply interruptions on customers but, working with the water sector, we’ve recognised more research is needed on how to protect these vital assets, assess new pipe materials and more accurately predict when they might fail.
“As a result of this innovative project, water companies now have a methodology to apply to their asset databases to better understand the ageing process of PE pipes and predict their remaining service life. They can then use this information to plan and target future investment in their water supply networks.”
The research also informs a number UKWIR’s Big Questions to help address the industry’s biggest challenges – namely “How do we achieve zero interruptions to water supplies by 2050?” and “How will we achieve zero leakage in a sustainable way by 2050?
UKWIR and Severn Trent Water has each funded the project with both organisations teaming up to present the findings to the wider industry. The pipes themselves were exhumed and tested in the winter of 2019/20.
And what of the testbeds themselves? One has been decommissioned but the other lives on with Jo Claronino adding: “The remaining testbed still has a significant amount of information to give to future engineers and so we will continue to maintain and re-test it.”