Case study 5 Experience with plastic sewers and drainage pipes

The first pipes made from PVC were pressure pipes and came into ye, on a small scale, shortly before the second world war. It was not until the early 1950s that the big growth in this application really began, and it took a further ten years or so for the excellent experience gained in pressure-pipe applications to motivate tests on pipelines of a very different character; that is, non-pressure applications in buried sewers and drains. 

At this time, a great deal was known and had been written about the behaviour of rigid pipes in the soil; we were however, rather ignorant about ground effects on flexible pipes, and very little usefull information can be found in the technical literature of'the period. 

It is significant that thin-walled pipes were chosen for the first installations because of the belief that this type of pipe was only required to act as a liner to protect a waterway from ingress resulting in collapse, as happens with tracks of moles. 

On visual inspection, many of these first non-pressure pipelines appeared to be satisfactory and aroused little comment or criticism. Others, however, indicated that deformation was taking place and drew attention to the need to measure exact deformation in existing pipelines, and, further, to devise means of predicting deformation in advance.