Lifetime of Pipes # 1992 Eindhoven
When plastics pipes are installed in water reticulation or pumped sewer systems they are normally subjected to installation damage, the level of which can vary enormously depending on the care taken during installation. Cyclic pressure testing of uPVC pipes with various levels of simulated installation damage, according to a representative pressure cycle such as that prescribed in Australian Standard AS 3707 (1). has shown that there is a direct relationship between the level of damage and the lifetime that can be expected from the pipe. Theoretical modelling of this experimental damagellifetime relationship, using a fracture mechanics approach that incorporates several novel features, has shown that we can predict the lifetimes of uPVC pipes subjected to cyclic pressures of different amplitude and frequency. This model incorporates the effects of time and test conditions on a range of factors, such as crack growth rate, stress intensity geometric factor, frequency, fracture toughness, mean stress, residual stress, and crack tip ductility.