Reduce Flow-Induced Thermowell Mechanical Stress

Jim Cahill

Chief Blogger, Editor

Thermowells, as tubular fittings in pipes and vessels, provide protection for temperature measurement devices. As we highlighted in a post from several years back, New Thermowell Calculations Help Avoid Damaging Resonance, they are subject to the stresses and strains from the fluid flowing by.

In a LinkedIn article by Emerson’s Timchan Bonkat, Rosemount Twisted Square Thermowell A New Twist in Thermowell Design, he describes this innovative technology:

The Rosemount Twisted Square thermowell is a revolutionary patented design manufactured specifically to eliminate the concern of vortex induced vibration that can lead to thermowell stem failure. It damps the vibrations by over 90%, drastically reducing the dynamic stresses experienced by the thermowell.

This 3-minute YouTube video, Twisted Square™ – A New Twist on Thermowell Design, shows a cutaway view of a traditional thermowell and a Rosemount Twisted Square thermowell at increasing flow rate conditions. The setup for this comparison are two 19-inch thermowells—a traditional straight type and a Twisted Square type.

A test lab flow loop is used with a 6-inch pipe and water flowing at rates from 0 to 28 feet per second. An accelerometer is placed on the tip of each thermowell to measure the vibration at changing flow rates.

A clear display into the piping shows the actual vibration and the accelerometers record and chart these vibration levels. The chart shows two “keep out” flow regions where the traditional thermowell experiences significant resonance—up to the point of failure for the upper flow rate end of the traverse vibration region.

Watch the video to see the huge difference in mechanical stress placed on traditional thermowell versus the Twisted Square design. The video closes by highlighting the following advantages:

  • Suppresses over 90% of dynamic stresses
  • Has NO frequency keep out zones
  • Peace of mind for applications with changing flow conditions
  • Simplifies and reduces complexity of thermowell design
  • Improves temperature accuracy without compromising safety

You can connect and interact with other temperature measurement experts in the Temperature group of the Emerson Exchange 365 community.

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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.