In order to avoid any damage to the thermowell during operation due to mechanical loads, a thermowell calculation per ASME PTC 19.3 TW-2016 is recommended for critical process conditions. In case of a calculation with negative results, the only constructive solution so far was to shorten the thermowell stem or to increase the root and tip diameter, accepting a longer response time of the thermometer.
The new ScrutonWell ® design reduces the amplitude of oscillation by more than 90 % and allows an easy and fast installation of the thermowell without support collar, and thus without expensive and time-consuming rework on site.
This helical design has been used successfully for decades in a wide variety of industrial applications to effectively suppress vortex-induced shrinkage excitation.
Functional principle
Standard thermowell
In certain flow conditions, a Kármán vortex street can form behind the thermowell stem when it is subjected to a flow within a pipeline. This vortex street consists of two rows of vortices with opposite directions of rotation, which detach themselves to the left and the right of the thermowell out of phase, and this can instigate the thermowell to vibrate.
NEW ScrutonWell ® design
The helical strakes, arranged around the thermowell stem of the ScrutonWell ® design, break up the flow and thus impede the formation of a clearly defined Kármán vortex street. Through the reduced amplitudes of the diffused vortices, vibrational excitation of the thermowell is avoided.
The NEW ScrutonWell ® design can be used for all kind of solid machined thermowells with flange connection, in Vanstone design or for weld-in or screwed process connection.
Note
Further information on our thermowells can be found on the WIKA website.
Learn more about the new ScrutonWell® design in the following video: