High Performance Fusion Jointing of PE-X Pipes [PEX]

Fusion jointing of cross-linked polyethylene (PE-X) pipe systems can be achieved by the use of conventional electrofusion (EF) couplers. The body of these couplers are manufactured from thermoplastic polyethylene, hence the performance of the joint is limited by the response of the body of the EF coupler. We report on a new form of fusion joining for PE-X pipe that utilises a PE-X bodied coupler capable of operating at pressure at temperatures up to and beyond 60°C. With this technology a bimetallic cage is contained within the coupler, and a current induced to flow within the cage. The temperature of the cage increases up to a set limit and is maintained at that fixed temperature for the required time to form the fusion joint. It will be shown that joints formed between these new PE-X bodied couplers and PE-X pipes pass those tests specified for conventional EF couplers. However, and uniquely, this PE-X coupler has exhibited lifetimes in excess of one year when pressure tested at a temperature of 110°C. These results show it is possible to create a fusion jointed PE-X based pipe system capable of operating at PE-X pipe performance levels. This allows the system to be used with reduced design factors or high pressures, and to be used over a wide temperature window.