Water & Wastewater Treatment Magazine
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32 | NOVEMBER 2017 | WWT | www.wwtonline.co.uk The Knowledge: plastic pipes SUMMARY • Choose well: The inherent corrosion resistance of plastic pipes means that they retain the same performance throughout their lifetime. • Design well: Use the method given in BS EN 1295-1:1997, but don't spend time in more complex calculations. • Install well: To achieve the best results at the outset – but plastic pipes are very tolerant of less than perfect site conditions. • Rest easy: The composite nature of pipe and ground is future-proof to increased traffic loads and volumes. What about traffic loading? The loads from traffic and surface loads are taken up by the ground sur- rounding the plastic pipe. The TEPPFA buried pipe study has shown that when pipes are more rigid than the soil that sur- rounds them, the pipe itself has to resist all the loading from above. Plastic pipes, correctly installed with well-compacted backfill material, spread the load to the ground itself – meaning they are subject to lower loads than traffic and weight of soil exert. Once the backfill and soil have settled a er installation, traffic loads have no further impact on pipe deflection. Is designing thermoplastic struc- tured wall pipe installations com- plicated? The accepted UK method for the de- sign of non-pressure pipelines is included in BS EN 1295-1: 1997 Annex A. Clear and well-presented supplementary guidance is included in BS 9295: 2010 Guide to the structural design of buried pipelines. This guidance is easily accessible to pipeline engineers and ensures that a good design can be carried out without the need for complex calculations. Much of the background research has been carried out using complex design and evaluation methods such as Finite Element Analysis. BPF Pipes Group members are active in the UK and European Standards committees which translate the experience developed over the last 30–40 years into practical design methods and guidance. What about large diameter pipes? Structured wall thermoplastic pipes in diameters ranging from 400mm to 2200mm have been in use in Europe since 1985 and in the UK since 1995. The size range was extended to 3000mm in 1999 and to 3500mm in 2008. BPF Pipes Group members who supply these large diameter pipes can help with scheme designs where calculations can be performed to the latest Eurocodes. Experience has shown that using large diameter pipes can equal other more tra- ditional solutions in performance and can offer a range of added benefits as well. Dr Vasilios Samaras of BPF Pipes Group member Asset International says: "Through extensive and sound research, the benefits of using thermoplastic pipes have been proven. The evidence is irrefu- table and by using best practice tech- niques, excellent long-term performance, asset life and protection of the entire pipe network can be achieved." Info: www.discover-plasticpipes.com/uk WATER NORTHERN IRELAND CONFERENCE 22 FEBRUARY 2018 | BELFAST ● Assess the strategic priorities for PC21 and long-term investment ● Gain insight into Northern Ireland Water's capital delivery plans ● Hear from industry leaders on the keys to success with digital transformation EXPERT SPEAKERS INCLUDE: BOOK NOW events.wwtonline.co.uk/ni SUPPORTED BY Linda MacHugh Director of water policy & shareholder division Department for Infrastructure Jenny Pyper Chief executive offi cer Utility Regulator Sara Venning Chief executive offi cer Northern Ireland Water Chris Jones Research and development manager Northumbrian Water Catriona Davis Chief inspector of drinking water Drinking Water Inspectorate Jane Mellor Head of operational procurement Northern Ireland Water Nick Mills Head of wastewater innovation Thames Water INVESTING IN HEALTH, THE ECONOMY & THE ENVIRONMENT This is the only event that brings together the leaders of the major stakeholder groups to address the current and future challenges facing the Northern Ireland water sector. WWT-WaterNI2017-HPHad.indd 1 12/10/2017 12:20