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During water hammering, moving fluids experience a sudden and powerful change in momentum, either changing direction or completely stopping, causing a high-pressure shockwave that spreads through a piping system, wreaking havoc on subsequent systems. This shockwave produces a banging or knocking sound that can be heard immediately after the shutoff takes place.
This sudden change in direction or complete stop occurs when an open steam trap or valve is abruptly closed. When the valve is closed, the water no longer has an open route to take, and it either slams mercilessly into the valve or reverses direction and flows back into the pump.

The Effects

While it may not seem like much of a threat on the surface, as the water travels through the piping, it continues to build up momentum, and when this force is suddenly halted, it creates pressure spikes that can reach an excess of 10 times the operating pressure of the system.

Water hammer requires swift and immediate action to prevent damage; failing to take action can have serious repercussions, including:

• Pump and flow system damage: Recurring water hammer and the resulting force that it generates can cause considerable damage to other parts of the entire system, including pumps, steam traps, and valves.
• Leaks: Over time, water hammer can damage and degrade the integrity of parts such as fittings and joints, leading to leaks.
• Risk of Accidents: The resulting ruptured pipelines caused by water hammer can pose a serious threat to the health and safety of your employees. Uncontrolled leaks increase the risk of slips, falls, and electrocution.
• Unscheduled Downtime: Water hammer and its damaging effects can lead to costly repairs and equipment replacement.

Prevention & Inspection

Several other effective measures for preventing water hammer include:

• Flushing old systems
• Reducing the operating pressure
• Adding pressure reducers and regulators in the supply line
• Investing in air chambers for piping systems
• Installing silent check valves to reduce the pressure

Investments can also be made into acquiring inspection instruments: ultrasound is usually the most suited technology to inspect steam traps & valves, as these instruments can be used in any type of steam traps and inspection can be carried on while the system is in operation. Inspecting steam traps and valves with ultrasound is a simple method that can help quickly identify failing or defective steam traps and valves.

Text: Peter Boon – Product Specialist at UE Systems Europe
Images: UE Systems Europe