Influence of Material Quality on the Performance of Thermoplastic Piping Systems

摘要

From various research work it is well known that a high resistance of polyethylene (PE) to slow crack growth (SCG) is decisive for the long-term behavior of heated tool butt welds. However, far less information is available about the extent to which this knowledge is transferable to other welding methods (e.g.: electro fusion welding) or to other materials. Therefore, electro fusion sockets and tapping saddles made of PE as well as heated tool butt welds made of polypropylene (PP) and polyvinylidenefluoride (PVDF) were investigated in the presented research work. Using fatigue testing and tensile creep tests the long-term performance of the welds was determined and compared with the slow crack growth resistance of the material. All results showed that the crack growth resistance of the utilized materials exerted a crucial influence on the long-term behavior of the welded joints. Thus, thorough material selection is of utmost importance to ensure long life-times.