Temperature Measurement
Daily Helix Thermowell (DHTW™)
- Daily Thermetrics is the exclusive supplier of the Daily Helix Thermowell (DHTW™) utilizing the patented VE Technology®.
- VE technology® combines helical strakes with a hemispherical tip which results in a special geometry that change the characteristics of the vortices created and prevents vibration induced failures.
- Multiple industries utilize the helical strake design and have proven its effectiveness in preventing vibrational failure through thousands of hours of service life.
Flow past cylindrical thermowells creates alternating vortices which induce thermowell vibration at the vortex shedding frequency. Mechanical resonance occurs when the vortex shedding frequency reaches the natural frequency of the thermowell and causes a dramatic increase in dynamic stress. ASME PTC 19.3 TW recommends standards based upon calculated results to prevent several different thermowell failure modes. Often, the conservative formulas and assumptions in the ASME code tend to be very prohibitive for high velocity applications. Traditional measures to mitigate these effects include using a collar, creating a bulkier thermowell, or shortening the nozzle length. Although these methods can prevent thermowell failure, they also have significant shortcomings. Larger diameter thermowells reduce temperature sensing accuracy, delay response times, and transfers a larger drag force to the nozzle. Collars require an interference fit which is difficult to achieve and is not recommended by the ASME PTC code due to the inconsistent nature of installation. The clear solution to high velocity applications is the Daily Helix Thermowell (DHTW™) utilizing VE technology®
