The tool calculates a thermowell’s ability to withstand stresses under given process conditions, enabling users to properly size their tubular fittings for protecting temperature sensors. Because a thermowell is subjected to a variety of stresses, typically because of in-line and transverse vibrations, it is necessary to run calculations on the thermowell design to make sure the stresses do not exceed the maximum allowable limit.
PTC 19.3 TW-2010 establishes the practical design considerations for thermowell installations in power and process piping. This code is an expanded version of the thermowell section contained in the PTC 19.3-1974, and incorporates the latest theory in the areas of natural frequency, Strouhal frequency, in-line resonance, and stress evaluation.
■ Expanded coverage for thermowell geometry
■ Natural frequency (resonance) correction factors for mounting compliance, added fluid mass, and sensor mass
■ Consideration for partial shielding from flow
■ Intrinsic thermowell damping
■ Steady state and dynamic stress evaluations
■ Improved allowable fatigue limit definition.
The standard is Intended for:
■ Pipging designers
■ Instrument engineers
■ Instrument designers and plant IC engineers and designers
■ Plant engineers
■ Plant safety engineers
■ Process engineers
■ Thermowell manufacturers
■ Instrument manufacturers.
The thermowell sizing calculator, Endress+Hauser says, helps users avoid thermowell failure, loss of measurement, damage to expensive equipment, and safety risks to plant personnel. Enrichments in the tool include a larger variety of thermowell geometries, such as stepped thermowells, and resonant frequency calculations allowing the maximum thermowell length to be determined based upon the process conditions.
The thermowell calculation tool is available on-line via the Endress+Hauser Applicator tool, a program that provides step-by-step assistance with product selection, sizing, and configuration. Users can try out the tool at http://www.us.endress.com/temp_manufacturing.