Measuring instruments supplier Wika Instruments offers its ScrutonWell as an alternative to a standard thermowell.
The ScrutonWell, manufactured by Wika, is typically used in applications commonly found in the chemicals and petrochemicals industry, where high flow velocity and aggressive process media can compromise the mechanical integrity of standard thermowell designs.
The ScrutonWell is used as an alternative to a standard thermowell, when a standard thermowell is exposed to vortex induced vibration that can lead to mechanical fatigue and failure of a standard thermowell.
The main purpose of a thermowell, or in this case the ScrutonWell, is to protect the temperature sensor from direct exposure to the process, as well as to ensure safe dismounting of the temperature sensor from the process without exposing plant personnel or the environment to the process media.
The ScrutonWell design conforms to American Society of Mechanical Engineers (ASME) Performance Test Code (PTC) 19.3 TW 2016 standards.
The company explains that this standard applies to thermowells machined from bar stock and includes those welded to or threaded into a flange as well as those welded into a process vessel or pipe with or without a weld adaptor.
Notably, thermowells manufactured from pipe are outside the scope of this standard.
Additionally, it is best practice that end-users verify existing thermowells using the wake frequency calculation as per ASME PTC 19.3 TW – 2016 during a debottlenecking project, to ensure that the thermowell will operate safely with the new process parameters – if any – before start-up.
Debottlenecking is desirable for many large operations, as minor percentage increases in output capacity by means of optimisation of existing equipment will result in significant profit returns.
During debottlenecking, reconfiguration of existing process equipment, and control loops are performed with the aim of optimising the process for an increased output/product yield without necessarily increasing the size of the plant.
Process parameters are often changed to allow for improved optimisation, which, in turn, results in the operating ranges of measurement instrumentation needing to be re-evaluated and often this equipment is recommissioned.
Thermowells, although not classified as measuring equipment, are also affected by this change, as high flow velocities can result in vortex-induced vibration on a thermowell.
With the ScrutonWell design from Wika, no further mechanical enhancements to the existing thermowell installation are required whilst the vortex-induced vibration is almost completely eliminated.