Fast weld field trials - high productivity butt jointing of polyethylene pipes

This research work took place up to and during 1997 and the results hereafter are from that research. However, since then there has been additional research work. For the purposes oF this paper the principles remain fundamenlally consistent; however, the rea.der should recognise the concept has been relined since the paper was initially published. The butt fusion procedures used in the UK water and gas industries, which determine the total time taken lo complete a successful joint, have remained largely unchanged since their harmonisalion in 1990. The parameters evolved to suit ma.nually operated butt fusion machines and reflected the fact that the minimum achievable heater plate removal time, for up to 250mm diameter. was between 6 and 8 s, during which the operator had to manually operate a hand pump to remove the healer. With standardisation of automatic butt fusion, and typical healer plate removal times of 2 s, the potential exists to reduce considerably the on site jointing time and thus enable substantial tinancial savings. Trials to date have been exclusive to second genera.lion medium density polyethylene PK80, due to its known tolerance to variances in jointing parameters, which can occur with manual machines working in site conditions. Further work to determine the fast weld parameters of third generation high density polyethylene PEIOO is planned for the future.