Polyethylene (PE) pipe will expand and contract by approximately 250mm for every 100m of pipe over a 10°C change in pipe temperature. For below ground installations, no allowance for expansion is required provided the connection system has stabilised to service temperature before backfilling. With above ground installations, thermal contraction is allowed for by ‘snaking’ the pipe.
Metric PE pipe is manufactured in accordance to Australian Standard
AS/NZS 4130:2009 - Polyethylene (PE) pipe for pressure applications.
By convention, PE pipe is often designed on the basis of 50 year life. This is an established international practice but is not intended to imply the service life of pressure pipe is limited to 50 years.
For correctly manufactured and installed systems, the actual life cannot be predicted, but can be expected to be well in excess of 100 years before major rehabilitation is required.