Thermowells Reducing Fatigue Failure in Challenging Process Conditions
Rosemount Twisted Square Thermowells eliminate over 90 per cent of dynamic stress, a leading cause of thermowell failures.
Emerson has released the Rosemount Twisted Square Thermowell line, a solution that reduces dynamic stress, simplifies process calculations and provides more accurate temperature measurements. This new design was developed to address these issues while meeting demanding production requirements, increasing output and ensuring high product quality.
The solution improves reliability and reduces the risk of fatigue failure through their ability to dampen dynamic stresses caused by oscillating vortex pressures, opines the firm. These dynamic stresses can result in vortex-induced vibration (VIV), which is the primary source of thermowell stress failures.
The new design reduces VIV by over 90 per cent. According to the company, this helps to simplify process calculations by eliminating the need to size thermowells to reduce dynamic and frequency limits. This also helps to save engineering time and lower costs without requiring design changes. It is ideal for use where conventional thermowells fail to meet the globally-accepted ASME PTC 19.3 TW standard for safe and reliable thermowell design.
Twisted Square Thermowells solve these challenges at a time when manufacturers are relying more on applications that require thermowells to withstand harsh or changing process conditions.
Typically, conventional thermowells are shortened and/or the outer diameter is increased to avoid VIV. The firm explains that these changes can result in decreased accuracy and/or slower response times for the measurement point. The dimensional adjustments recommended by the ASME PTC 19.3 TW calculations are often acceptable to maintain an appropriate measurement point, but in some cases, they may compromise temperature accuracy, making it difficult to implement.