High-density polyethylene (HDPE) lake pressure pipeline: Remaining service life after 47 years of operation in Lake Ossiach
In 1971, a high-density polyethylene (HDPE) pressure pipeline was installed in Lake Ossiach to efficiently discharge wastewater. Investigations and tests indicate that this pipeline can continue to operate for at least another 50 years, even though it has already reached its 50-year service life. Advances in HDPE materials and improved design standards could potentially extend its lifespan even further.
The stress crack and thermal aging investigations revealed a minimum remaining service life of 50 years for the tested sample. However, it’s important to note that local stress concentrations, such as those at the concrete support rings, were not taken into account. These findings support the service life predictions made in the 1960s, based on the creep tests conducted at that time.
The material used in those early years is considered "1st generation" HDPE pipe material. In contrast, modern materials like PE 100 and PE 100-RC not only provide higher design stresses but also significantly enhance resistance to slow crack growth. Additionally, advancements in additives have improved protection against thermal aging.
We would like to thank Mr. Dipl.-Ing. Norbert Schwarz and his colleagues from the Water Association Ossiacher See in Carinthia, Austria, for providing the samples and collaborating on this publication.
3R international - Issue 09, 2019, pages 74-80
