De Rosa, Spence
# 2004 Milan
The cost benefits of thin walled MDPE pipe systems for the rehabilitation of gas and water mains are significant. However, the key short-term factor in making decisions about rehabilitation and replacement choices is often the initial cost of the work, rather than the total cost of ownership. The various spray-applied internal coating options that have previously found favour in the UK for water mains rehabilitation have been used primarily to tackle water quality problems. Their attraction has been the low initial cost, which is due to the fact that they do not normally require the accessing of the service connection. They do not, however, address the issue and consequences of leakage or burst mains. The performance of medium density polyethylene (MDPE) is now backed up by a substantial platform of historical data generated over 20 years, which indicates that lifetimes of pipeline products made from modern PE resins are likely to be well in excess of 100 years. Thinwalled linings using PE or reinforced PE are now used to renovate mains and, designed correctly, will ensure their subsequent long-term performance. Examples are given of the costs and savings that can be achieved using PE liners, together with examples of the successful commercial application of thin-walled liners in both the water and gas industries.