Predicting the residual life of PVC sewer pipes

Ipswich Water commenced reviewing the service lives of different pipe materials in its gravity sewer system. Unlike other pipe materials, PVC sewers had no failure histories nor deterioration revealed in CCTV inspections, even after 25 years of service. Therefore, establishing a realistic predicted life was not possible using statistical analysis of historical field failure data. The approach taken was to exhume a number of elastomeric seal jointed PVC sewer pipes that had been in service for periods of up to 25 years. The samples were tested for selected mechanical properties and joint performance characteristics which might be considered age dependent. The results indicated there had been no deterioration in the material and the joints continued to meet current performance specifications. Two methods of quantifying the condition of PVC sewer pipelines and predicting the residual life are suggested. Based on this analysis, the pipelines examined have not exhibited any significant deterioration and should provide many more years of service.