Lang, Pinter, Balika, Haager
# 2006 Washington DC
The current discussion and future situation in the field of polyethylene (PE) pressure pipes for water and gas supply may be characterized by the following aspects and topics. Continuous developments by polymer suppliers in the last decades have resulted in improved PE material grades, which in turn led to a significant rise in maximum operating pressures for pipes, with further enhancements perhaps to be expected. Moreover, based on cost reasons an increase in minimum service life from currently 50 to possibly 100 years has been proposed most recently by some for the last generation PE materials of the PE 100 type. Simultaneously, and also due to increasing cost pressure, considerations have been put forth for the installation of buried PE pressure pipes without sand embedding, which have led to some controversy. A main problem in this regard concerns the reliability of such pressure pipes with significant additional local or regional loads, particularly the safety against the formation and slow growth of cracks which may induce ultimate pipe failure. The present paper describes the main elements of a novel concept for lifetime and safety assessment of PE pressure pipes for arbitrary installation conditions based on modern methods of fracture mechanics. At the core of the proposed concept is the accelerated generation of so-called „synthetic“ crack growth curves and corresponding material laws for crack growth initiation and slow crack growth for service-near temperature conditions without the use of stress cracking liquids.