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Thermowells Service

Pressure and Velocity Ratings
The factors required to provide increased thermowell strength reduces the accuracy and response time of temperature elements. Thermowell designs must carefully balance all factors so that accuracy effect is kept at a minimum while maintaining adequate strength.

Thermowell failure is caused by vibration, pressure and steady state flow. Separate evaluations are required to determine the suitability for any application in question. Failures are not normally due to pressure or temperature. Calculations are necessary in choosing proper diameters (wall thickness) and materials for a given application.

Vibrational effects are more likely to cause thermowell failure. Fluid flowing by the thermowell forms what is known as the Von Karman Trail. This is a turbulent wake that has a frequency based on the diameter of the thermowell and the velocity of the fluid or media. The thermowell must have sufficient stiffness so that the wake frequency will never equal the natural frequency of the thermowell. If the natural frequency and the wake frequency become equal, the thermowell will vibrate to destruction. Calculations can be utilized to determine if a thermowell is acceptable under given conditions for a particular service.

The sales staff at TMS is capable of offering assistance in selecting materials and/or thermowells for a given service. Suggestions can be offered based on information about the particular application.