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Thermowell Wake Frequency Check
ASME PTC 19.3 TW Preliminary Screening
Flow & Fluid Properties
Flow Velocity (V)
m/s
ft/s
Fluid Density (ρ)
kg/m³
lb/ft³
Viscosity (μ)
Pa·s
cP
Thermowell Geometry
Tip OD (B)
mm
in
U Length (L)
mm
in
Stem Style
Straight (K≈1.0)
Tapered (K≈1.15)
Stepped (K≈1.05)
Added Mass (C
m
)
Material Properties
Material Preset
SS 316 / 316L
SS 304 / 304L
Carbon Steel
Monel 400
Inconel 600
Hastelloy C-276
Custom (Edit below)
Modulus (E)
GPa
ksi
Density (ρ
m
)
kg/m³
lb/ft³
Validation & Check
Frequency Analysis
Natural Freq (f
n
)
—
—
Strouhal Freq (f
s
)
—
—
In-line Freq (2·f
s
)
—
—
Detailed Parameters
Reynolds Number (Re)
—
Strouhal Number (St)
—
Ratio f
n
/ f
s
(Transverse)
—
Ratio f
n
/ 2f
s
(In-line)
—
Reduced Velocity (Vr)
—
Eff. Mass (kg/m)
—
Moment of Inertia
—
📄 Export Report
🔄 Reset Defaults
Technical Notes & Engineering Logic
Variable Definitions
f
n
(Natural Freq):
The frequency at which the thermowell naturally vibrates.
f
s
(Strouhal Freq):
The frequency of vortex shedding caused by fluid flow.
r (Ratio):
Safety ratio. Standard requires f
n
≥ 1.25 × Excitation Frequency.
Formulas
Strouhal Freq:
f
s
= (St × V) / B
Natural Freq:
f
n
= (K / L²) × √(EI / m
eff
)
Pass Criteria:
Avoid resonance zones. Typically r > 1.25 is safe.
Assumptions
Calculated as a cantilever beam with uniform load.
Does not account for fluid pressure limits or stress calculations (bending/steady-state).
ASME PTC 19.3 TW requires checking both Transverse (f
s
) and In-Line (2f
s
) resonance.