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How Water Hammer Happens In Steam Applications

Nov 15, 2017

innovamass water hammer Sierra

Many of us have heard the sound of pipes banging as we turn a faucet on or off. This sound is the water in the pipe being forced to stop or suddenly change direction and is called “water hammer.”

Did you know that water hammer is not just limited to water pipes? In fact, water hammer, more generally called  “fluid hammer” or “hydraulic shock,” is possible with any gas, liquid, or steam.

The Main Cause of Fluid Hammer in Steam Pipes

How does fluid hammer in steam piping occur? In many steam plants, steam under high pressure is held behind an isolation valve (also called a “steam stop”). If you open that valve too fast, the steam enters the cold downstream piping and condenses into water.

In some cases, this slug of condensed water can act like a bullet. This hydraulic shock happens because steam flow velocity can be ten times faster than water flow.

Pushed by the steam behind it, the water bullet can break and shear off anything in its way, like gate valves, orifices, and insertion meters. Think of shooting a drop of water through a straw. The picture below is a Sierra InnovaMass® vortex meter that was damaged by fluid hammer. You can see that the temperature sensor has been sheared away!

Reducing the Likelihood of Fluid Hammers In Steam Applications

innovamass water pipe sierra

Steam fluid hammers can be damaging, but fortunately, they are preventable. Here are some ways you can avoid fluid hammers in your steam pipes:

  • Warm up the downstream piping to minimize condensation. This is why most steam plants have a bypass valve around all their big stop valves so they can bleed steam into the pipe.

  • Install steam traps to collect any condensation that does form.

  • Monitor temperature, pressure, and steam velocity. These metrics should be watched closely, especially during s startup. Having the ability to monitor and adjust your flow meters in the plant with apps is crucial to not only preventing water hammer, but ensuring optimal energy flow management.

Check out our InnovaMass Vortex Flow Meters for your steam application >

Charlotte Chapman, Sr. Graphic Designer
Written By:
Charlotte Chapman, Sr. Graphic Designer
Sierra Instruments

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