MSc. J. Weller, R.J.M. Hermkens
5 minute posters # 2014 Chicago
More than 75,000 km of PVC pipes are currently in use for the distribution of natural gas in The Netherlands, which make up over 60% of the distribution grid. To gain insight in the factors that influence the quality of those pipes a so called Exit Assessment programme was started in 2004. Part of this programme investigates how the handling of these pipes is influencing their quality. It is shown that PVC pipes wrapped in plastic sheet material are efficiently protected against UV-degradation.
In this research PVC (PVC-U, PVC-A and PVC-CPE) pipes have been exposed to direct sunlight with periods varying from 1 month to a year. Half of these pipes were wrapped in standard packaging sheets. Using a further improved test method  the ductility of these pipes was measured. Field failure studies have shown that the lack of ductile behaviour is the most important reason for incidents involving PVC gas pipes. With the further improved test method the ductility of the PVC pipes was determined at temperatures ranging from -25°C to +50°C. With this method it is possible to determine small changes in the ductile-brittle transition temperature of PVC. The influence of direct sunlight was shown by comparing the side of the pipe that was exposed to direct sunlight with the side that had been in the shadow. It also enabled us to measure the influence of using protective plastic sheet material.
Influence of direct sunlight on PVC without sheet material was measurable and visible after 3 months. The plastic sheet material proved to be an excellent protection against UV-degradation and preserved its function during the test period of one year. This also underlines the importance of using the plastic sheet material.