High-density polyethylene (HDPE) pipe is now being used as an alternat
ive to medium-density polyethylene (MDPE) for gas, water, sewage and w
aste-water distribution systems. Laboratory tests appear to show that
HDPE is more able to suppress rapid crack propagation (RCP), whilst re
maining sufficient resistance under the operational circumstances that
lead to the type of slow crack growth observed in service failures. T
here have been many fractographic studies on MDPE pipe materials, actu
al pipe and fittings, but little on HDPE. A fractographic study of the
type of HDPE pipe in current production has been undertaken. For thes
e tests, whole pipe sections were subjected to either static or dynami
c internal (water) pressurization fatigue loading. Failure mechanisms
are discussed based on the fracture morphologies resulting from these
tests. A further argument for good resistance of HDPE pipe to RCP is s
uggested. (C) 1998 Chapman & Hall.