The fatigue performance of electrofusion tapping tees subject to contamination

Electrofusion jointing is a common joint process used to weld polyethylene (PE) water pipe in the UK. For many years, the UK Water Industry has experienced a small number of premature failures of electrofusion fittings; this inevitably causes leakage. The common causes of critical failures have been highlighted and as a result of this, a testing programme was designed and implemented to assess the fatigue performance of electrofusion tapping tees if they were to be installed by ‘bad practice’. A fine china talc was used to replicate contamination in the field. The results suggest that failures associated with fatigue are possible in a relatively short space of time on tapping tees when they are subject to contamination. The pressure ranges used in the fatigue regime aimed to replicate the potential magnitude of surge pressures that can be experienced in water distribution mains.