Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | MAY 2015 | 33 In the know Getting to grips with... electrofusion jointing The right fi t? Electrofusion pipe jointing has received a bad press, but any problems that are present usually stem from poor fi tting practices P olyethylene (PE) plastic pipes are widely installed throughout the water and wastewater treatment industry as the material of choice for conveying water, yet certain methods of jointing the pipelines are beginning to develop a poor reputation. Electrofusion jointing has come under much criticism over recent years, not least because of a UK Water Industry Research Limited (UKWIR) report claiming that up to 20% of PE electrofusion joints fail before they reach their design life, due to poor site practice. As a result, this method of jointing plastic pipes has come under severe scrutiny, leading to several water companies questioning the use of electrofusion ‚ ttings to join their pipelines. Why have some water companies banned the use of these fi ttings? There has been a lot of publicity surrounding the integrity of electrofusion ‚ ttings. In the report published by UKWIR, the industry focused on the headline stating that 1 in 5 electrofusion joints would fail before their expected lifetime. UKWIR later published a statement saying that its report had been misinterpreted, and reinforced the message that PE pipes have the lowest failure rate among di‡ erent materials used in the construction of water BOB WARREN TECHNICAL SUPPORT ENGINEER GPS PE PIPE SYSTEMS mains. However, the damage had already been done, and the report led to some water companies banning the use of these ‚ ttings without properly understanding the real issues. In contrast to industry beliefs, analysis of products that have been returned, reveals that less than 1 in 10,000 ‚ ttings are returned to manufacturers due to product failure. How does electrofusion jointing work? Electrofusion is a method of joining plastic pipes by using ‚ ttings with built-in electric heating elements, which are used to weld the joint together. The pipes to be joined are cleaned, inserted into the electrofusion ‚ tting and a voltage, typically 40V, is applied for a ‚ xed time depending on the size of the pipe and ‚ tting being installed. The built-in heater coils then melt the inside of the ‚ tting and the outside of the pipe wall, which melts together to produce a very strong homogeneous joint. What applications can electrofusion fi ttings be used for? Electrofusion jointing can be used to join new pipelines which are conveying water for a wide variety of applications. The exception is with projects in which plastic pipe is inserted into existing iron pipes as a cost e‡ ective way for water companies to upgrade their pipe networks. For insertion applications, butt fusion welding is preferred as this method of jointing results in one continuous pipe, o‡ ering easier maintenance. How long will an electrofusion joint last? If the pipe has been prepared in accordance with guidelines and the jointing process has been carried out correctly, by a competent installer, the ‚ tting is expected to last as long as the lifetime of the pipe system, and a minimum of 50 years. What can be done to ensure joints don't fail? The majority of ‚ ttings that leak do so because of poor quality workmanship or incorrect installation practices of the ‚ tting. The three main causes of joint failure when using electrofusion ‚ ttings are: - Poor joint preparation - Contamination of the joint caused during the jointing process - Misalignment of the pipe within the ‚ tting These failings occur due to poor site practice and poorly skilled installers of the pipe systems. In order to reduce the number of joint failures, and subsequent water leakage, the whole industry needs to adopt a cultural change to work together to address the issues of installation, best practice and electrofusion skills. An electrofusion coupler

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