Ultrasonic
Testing
Ultrasonic Testing Formula
Commonly used UT Formula are provided for reference
| Featured | Formula | Remarks |
|---|---|---|
| Surface Distance & Depth (1st Leg) |
SD
=
Sound path * Sin θR
Depth (1st leg)
=
Sound Path * Cos θR
|
Image |
| Surface Distance & Depth (2nd Leg) |
SD
=
Sound path * Sin θR
Depth (1st leg)
=
2T - (Sound Path * Cos θR)
|
Image |
| Skip Distance for weld inspection |
Skip Distance
=
2T * tan θR
|
Image |
| Wavelength |
λ
=
V
f
|
Where, λ = Wavelength V = Velocity F = Frequency |
| Near‐field (circular) |
N
=
D2
4λ
N
=
D2F
4V
|
Where, N = Near Field D = Transducer Diameter λ = Wavelength V = Velocity |
| Snell’s law |
Sin θI
Sin θR
=
V1
V2
|
Where, θI = Angle of the Incident Wave θR = Angle of the Reflected Wave V1 = Velocity of Incident Wave V2 = Velocity of Reflected Wave |
| Decibel (dB)Gain or Loss |
dB
=
20 (LogA2A1)
|
Where, dB = Decibel A1 = Amplitude 1 A2 = Amplitude 2 |
| Near‐field (circular) |
Z
=
ρ x V
|
Where, Z = Acoustic Impedance ρ = Density V = Velocity |
| Reflection coefficient |
R
=
( Z2 - Z1 )2
( Z2 + Z1 )2
|
Where, R = Reflection Coefficient Z1 = Acoustic Impedance of Medium 1 Z2 = Acoustic Impedance of Medium 2 |
| Beam divergence- angle (circular) |
Sin θ
=
1.2
λ
D
Sin θ
=
1.2
V
DF
|
Where, λ = Wavelength D = Transducer Diameter V = Velocity F = Frequency |
| Longitudinal (Compression) velocity |
VL
=
√
E(1 - 𝝁)
ρ(1 + 𝝁)(1 - 2𝝁)
|
Where, N = Near Field D = Transducer Diameter λ = Wavelength V = Velocity |
| Transverse (shear) velocity |
Vs
=
√
E
2ρ(1 + 𝝁)
√
G
ρ
|
Where, λ = Wavelength D = Transducer Diameter F = Frequency |
| Angle Beam testing of Pipe |
t
=
d(1 - Sin θ)
2
Sin θ
=
1 - (2td)
|
Where, t = Maximum wall thickness d = O.D. of Pipe θ = Probe angle |
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