(84c) Avoiding Water Hammer and Other Hydraulic Transients

This presentation focuses on water hammer, sometimes termed “hammer blow”, that occurs when a liquid pipeline valve is closed too quickly. Closing too quickly can cause “water hammer” on one side of the valve and “cavitation hammer” on the other. Oscillating pressure waves on both sides of the valve can cause damage to the equipment including pipe rupture. Similar phenomena may occur when starting and stopping pumps. As various situations can cause potentially damaging pressure waves, water hammer and related phenomena are grouped as “hydraulic transients”. These phenomena are not limited to water pipes and may occur in any liquid piping system including condensed gases such as chlorine, ammonia, and LNG. Various mitigation options will be discussed. These need to be evaluated during the design process rather than being added retroactively once a problem becomes evident.