ScrutonWell® : Designed to minimize thermowell vibration

Thermowell design and vortices

Thermowells are an ideal solution for protecting industrial temperature sensors when they’re inserted into corrosive or abrasive process media. However, when a long, narrow object encounters a rapid-flow condition, whether the medium is air or a fluid, it leaves behind, or sheds, a series of vortices swirling in opposite directions. Depending on the velocity of the flow, the vortices could be strong enough to cause significant shocks and vibrations that lead to mechanical fatigue throughout the instrument.

There are several ways to solve this problem, but they might not be sufficient to pass the wake frequency calculation (WFC) of a thermowell per ASME PTC 19.3 TW-2016:

  • Shorten the stem, which could make the thermowell too short to reach the process medium
  • Increase the root diameter, which could make the thermowell too wide to fit into the flange nozzle
  • Increase the tip diameter, which could increase the response time of the temperature sensor
  • Retrofit a support collar to stabilize the stem, which requires extensive on-site machining

A thermowell design proven to break up vortice

By breaking up the shed vortices so they’re smaller and weaker, helical strakes are extremely effective in dampening the effects of vibrational excitation in pipelines and other applications. The ScrutonWell® design, named after Christopher Scruton (one of the innovators of this solution), reduces the amplitude of oscillation by more than 90%*, and allows a fast and easy installation of a thermowell without the time and expense of on-site reworking. It can be used for all types of solid-machined thermowells with flange connection, in Vanstone design, or for weld-in or threaded process connection.

WIKA thermowells with ScrutonWell® design have been thoroughly tested and approved by the independent laboratory TÜV SÜD in Glasgow and the Institute for Mechanics and Fluid Dynamics at the Technical University of Freiberg.

Applications of the ScrutonWell® design

For many decades, helical strakes have been used successfully in a variety of industrial applications to suppress vortex-induced excitation. Our ScrutonWell® design is ideal for:

  • Chemical and petrochemical industries
  • Onshore and offshore refineries
  • Plant construction
  • The highest process loads
  • Applications in critical measuring points

Thermowells with ScrutonWell® design by WIKA

Our patented ScrutonWell design for reduced thermowell vibration is an option on all the following products.

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