THE EVALUATION OF FACTORS GOVERNING LONG TERM PERFORMANCE OF POLYETHYLENE ELECTROFUSION FITTINGS

摘要

It is widely accepted that in testing, the long term fracture mode for Electrofusion (EF) socket fittings is via Slow Crack Growth (SCG), initiating from the first wire turn from the centre cold zone of the fitting. This study examines the injection moulding process and the EF welding process and their potential to affect the SCG resistance of EF fittings. A range of commercially available PE 80 and PE 100 resins were selected for evaluation. EF fittings were injection moulded and welded under a variety of conditions. Testing via hydrostatic pressure methods at elevated temperature and the Full Notch Creep Test (FNCT) were used to assess SCG resistance of the fittings. The results from these tests on the chosen resins are analysed and conclusions made on the effects on SCG resistance, if any, of using a range of processing and EF welding conditions.