ABSTRACT
The objective of the study was to analyse dents in PVC-U sewer pipes observed in the initial phase of the operation called the “burn in” period. It is a part of the “bath curve” that shows the whole service life of pipes, and which also includes two further subsequent phases, namely normal operation and “wear out” period. CCTV investigations were conducted in eleven cities. The analysis focused on quantitative data concerning size and frequency of dents observed in the walls of PVC-U sewers. Classification of dents was proposed, based on the dent size defined as the dent depth to the pipe diameter ratio. The reasons for dent occurrence were indicated. It was explained why trenchless rehabilitation of PVC-U pipes with dents cannot be performed using close-fit methods.
