A methodology to estimate remaining service life of grey cast iron water mains

The decision to repair, renew, or replace existing old grey cast iron mains is typically based on performance indicators such as structural integrity, hydraulic efficiency, system reliability, and water quality. Structural integrity (often quantified as the number of main breaks per kilometre or mile per year) is the most common performance indicator. However, these indicators represent past performance, rather than expected future performance. Decisions based on performance indicators may not, therefore, accurately meet the real needs of the utility owner of the water distribution system. A preferred approach to make decisions on pipe repair and replacement is to determine the expected remaining service (residual) life of each pipe segment and ensure that the necessary work is performed before failure occurs. Past efforts to estimate remaining service life of water mains have been based on corrosion pit depth and estimated corrosion rate with no regard to the influence of corrosion on the structural resi...