Category
Instrumentation & Control
Subcategory
Temperature
Applicable standards
2
Issuing bodies
2
Description
Thermocouple temperature sensor (type K, J, T, N, etc.) per IEC 60584.
Applicable Standards (2)
ASME — 1 standard
ASME PTC 19.3 TW
Thermowells — Performance Test Codes
Strength and stability calculation of thermowells (vortex shedding, frequency, stress).
Key requirements (8)
- Thermowells — design and stress analysis (also as ASME PTC 19.3 TW).
- Velocity-induced vibration: avoid resonance (natural frequency ≥ 80% of vortex shedding frequency × scale factor).
- Strouhal number: 0.22 typical for cylinder in cross flow.
- Stress check: bending + drag + axial — combined < material allowable.
- Wake frequency formula (Strouhal): fw = St·V/D where D = thermowell tip diameter.
- Frequency ratio limit: scaling factor 0.4 (lock-in zone) to 0.8 (resonance).
- Mounting: threaded, flanged, socket-weld, welded.
- Insertion length (U): immersion depth into pipe; balance of response time vs vibration.
IEC — 1 standard
IEC 60584 (series)
Thermocouples
Thermocouple reference tables, tolerances, color coding (Types K, J, T, E, N, R, S, B).