This research studies the effect of abnormal operation conditions on water hammer phenomenon in
water supply pipe network in order to provide an acceptable level of protection against system
failure due to pipes collapse or bursting. Water Hammer and Mass Oscillation WHAMO software is
used in the analysis which uses the implicit finite difference scheme for solving the momentum and
continuity equations at unsteady state case. Assiut city water supply network is used in the analysis.
Flow of pipe network is studied due to; firstly, the sudden change in water demand at one or more
junctions, secondly, the closing of some pipes of the network on the transient pressure and flow
rates, and finally the failure in some network pipelines on intrusion or leakage due to transient
pressure head fluctuations. The previous cases are studied in steady normal case, without any
protection, and under different protection device(s) such as non-return valve and open surge tank.
The results showed that rapidly change in demand increases the pressure head and flow rate
fluctuations. Closing some pipelines increases pressure in a region and decreases it at another and
also changes the direction of flow in the network. Also, failure of some pipelines can cause
intrusion and leakage from outside the network to inside and inversely, which affects the values of
minimum pressure heads more than the maximum ones