Water & Wastewater Treatment

34 | MAY 2015 | WWT | www.wwtonline.co.uk In the know Getting to grips with... electrofusion jointing There are three areas of improvement that need to be addressed: Site Practice: With support from manufacturers, contractors and installers need to be ensuring the highest standards of installation. Manufacturer guidance on the installation of their systems needs to be to be enforced, while pipelines should only be tted by knowledgeable, skilled and quali ed professionals. Robust equipment: from torque spanners and hot plates to pipe alignment clamps, the installation equipment must be robust, reliable and t for purpose. It is also imperative that the correct equipment is used and not bypassed with the aim of completing the installation more quickly. Quality control: con rming that a genuine, leak-free joint has been made is critical and so a clear quality control procedure needs to be implemented, including on-site pressure testing and regular auditing and feedback to facilitate improvement. What other jointing methods can be used? The other commonly used method of jointing PE pipe in the UK is Butt Fusion welding, which involves heating two planed surfaces against a heated surface. A† er a speci ed amount of time the heating plate is removed and the two pieces are pressed together and allowed to cool under pressure, "The majority of fi ttings that leak do so because of poor quality workmanship or incorrect installation practices of the fi tting." forming the desired joint. As with electrofusion jointing, it creates a homogenous joint and is comparable in terms of cost and speed of installation, so it o† en comes down to application. Butt Fusion jointing requires more equipment so can sometimes be more costly on smaller pipe diameters, but can work out more economical on sizes above 90mm. The semi-automated process of Butt Fusion welding also reduces the risk of human error, and as such, failure rates are signi cantly lower. The other jointing technique that can be used is socket fusion, which uses custom-shaped and sized heating plates rather than a basic Š at surface. These heads allow for more surface contact, reducing the time needed to heat and fuse the pipe. Socket fusion requires less pressure than butt- welding and is more commonly used on smaller sizes of pipe 90mm or less. Other European countries seem to have strict regulations controlling pipeline joints. What is in place in the UK? Water utilities in countries across Europe take far greater responsibility for the jointing of pipelines, compared with those in the UK, with many requiring welders to be trained and third party certi ed before they are allowed to undertake such work. In the UK, there has been a relevant training and certi cation standard available since 2003 ('BS EN 13067: 2012 – Plastics welding personnel: Quali cation testing of welders and thermoplastic welded assemblies.) However, this standard has not been adopted by the UK water industry, which has led to poor workmanship and ongoing problems with the quality of electrofusion jointing. The UK water industry also has its own standard for product speci cation (WIS 4-32-08 'Fusion Jointing of Polyethylene Pressure Pipeline Systems'). Yet this standard is just advisory, not mandatory. European countries have adopted a diŸ erent set of standards to the UK and training bodies provide certi cation in accordance with DVS standards, with DVS 2207-1 and DVS 2212-1 being the relevant standards that are used. Both of these standards cover electrofusion, Butt Fusion and Socket Fusion jointing methods. The process descriptions of these standards are no diŸ erent to those available in the UK, but they include some speci c requirements in relation to quality and training, such as: 'every trainer has to be trained and in possession of a valid quali cation certi cate', and 'the welding work must be monitored'. These standards, along with the existing WIS guidance, need to be adopted and made mandatory in the UK. The entire water industry needs to take responsibility and work together towards achieving zero leakage by 2050. About the Author: Bob Warren is Technical Support Engineer at GPS PE Pipe Systems, a leading manufacturer of piping products for gas, water, sewerage and industrial applications. An electrofusion fi tting

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