# 1988 Bath
Elevated teqerature fatigue of MDPE pipe system showed socket and electrofusion fittings had similar fatigue lifetimes, while butt jointed pipes failed at repmducibly lower lifetimes. Extrapolatims to 2O'C preserved the raking in joint performance, although combined creep ad fatigre tests showed pure fatigue over-states total sustainable fatigue d-ge. Thee extrapolated fatigue lifetimes for MDPE systems, and published data on uPVC pipes, ere cocpared with fatigue damage fmm diurnal ad surge fatigue loading. uPVC pipes and MDPE pipe systems can sustain fatigue damge from diurnal pressure charges. Surge fatigue induces prenature failure in norm1 uPVC pipes and socket ard electrofusion jointed MDPE system. Oriented uPVC and butt jointed MDPE pipes exceed the desired 100 year life.