Stefan Dreckötter, Hugo Hammar
Papers # 2014 Chicago
Plastic Materials have been used in the hot and cold water segment for many years. Cross linked materials in different pipe designs can be used for these applications e.g. under floor heating and sanitary installations. Due to the cross-linked polyethylene network, long-term properties like creep resistance, high temperature resistance and resistance to crack propagation are greatly improved.
Various tests, like “the determination of the long-term hydrostatic strength of thermoplastic materials (ISO 9080)” 1.) have been developed and implemented into standardization in order to simulate the service life and to ensure a reliable product for the end user.
PE-Xc materials have been tested in accordance to ISO 9080. Usually ISO 9080 tests can be stopped after 8760h (1 year), and the lifetime extrapolated to 50 years. For this study however, the pipe samples were kept on test and continued until failure. At temperatures clearly above application temperatures very long lifetimes were achieved – thus proving the outstanding long-term performance of PE-X materials.
Also, the stress crack resistance of cross-linked PE materials was investigated using methods normally applied for non-cross-linked PE pipe materials, and even after years of testing no failures were observed for cross-linked pipes.