TNO Research: Lifetime expectation PVC pipes

TNO Research: Quality of PVC sewage pipes in the Netherlands

Original text in English

The residual lifetime of existing PVC (polyvinyl chloride) tap water pipe systems in the Netherlands was studied within the project “Expected lifetime of existing PVC water distribution systems”; 007.63549. The probable degradation processes, which can occur in PVC materials, were evaluated and quantified. It was concluded that mechanical loadings leading to crack initiation and growth will dominate the premature failures. The expected residual lifetime of most of the PVC water pipes studied was calculated to be at least 100 years, provided that the pipes are properly installed and operated and that damages in the PVC pipe walls are less than 1 mm in depth.

Another application of PVC pipes in the Netherlands is in sewage systems. BureauLeiding asked TNO Science and Industry to study the quality of some excavated PVC sewage pipes. One excavated PVC sewage pipe from the Dyka location and 6 PVC sewage pipe parts from the “BIS” (pipe collecting system) for old pipes were selected. The selection of the 6 parts was performed based on visual characteristics, remainders from the sewage sediment, and the presence of a readable print on the pipe stating its origin.

The PVC parts were assessed visually and microscopically by TNO Science and Industry after cleaning by soaking and rinsing. Special attention was paid to the surface roughness, the wall thickness and the permanent deformation. Moreover, the degree of degradation of the inner surface as a result of the contact with the sewage flow was determined.

The experimental results of this study are presented in chapter 2. A discussion on the expected lifetime of the PVC non-pressurised sewage pipes is presented in chapter 3 based on the experimental results and the crack growth resistance quantified in the former project on the existing PVC tap water pipes. The summary and the conclusions are given in chapter 4.