Surge and Water Hammer

This mostly directed at Geoff but all advice is welcomed,

We have a large closed network utilising insulated steel pipe and I am trying to understand the likelihood or risk associated with a pressure surge.

This network is entirely buried and we have not been commissioned to undertake the pumping plant design- so we have little control of valve selection and/or control within the plants.

There will be 3 pumping stations each pump is variable flow and all valves in the network are manually operated large diameter butterfly valves. Roughly there will be 20 pumps in each pumping station.

My limited understanding of surge and water hammer is that it relies on a fast change in pressure (by valve closure or loss of pumps etc) in the network which propogates through out the system causing if not catastrophic failure then fatigue.

The overall system pressure will modulate in accordance with demand but this will be controlled by VSD's on the pumps, also given that the entire network is completely restrained by the soil and that there is no real risk that a valve can be shut quickly...Is surge and water hammer still a potential risk on the system and why?

The size of the network dictates that any ramping up or down of pumps will not induce a rapid change in the network pressure. And even if one pumping station goes down because of power failure the other two will be designed to pick up the slack. My thoughts are that this still may induce a rapid change in pressure??

Can managing the operation (including the event of a failure) of the network in such a way as to avoid any rapid pressure variations be used to eliminate the risk or surge and water hammer?

Any ideas or comments?? Received on Thu Jan 12 18:02:00 2006