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Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

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Attenuation of couplants varies with material composition as would be<br />

expected. Published attenuation values are available <strong>for</strong> many materials as<br />

indicated in the table below. Attenuation coefficients are often quoted in<br />

Neper which allow <strong>for</strong> frequency dependence. 1 Np = 8.686 dB.<br />

Attenuation per unit length= Attenuation Coefficient x f 2 x 8.686 dB/cm.<br />

Table 8-1 indicates Attenuation Coefficient of some common liquids.<br />

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