Ultrasonic Questions Flashcards
The number of full, complete cycles in a given time (usually a second) is referred to as the:
Frequency
For most practical ultrasonic testing, the frequency is typically in what range?
0.5MHz-6MHz
Which of the following types of ultrasonic wave could be written as VL?
Compression waves
Longitudinal/Compression waves (VL)
Oscillate in same direction as the wave
Thickness and laminations
5940 m/s in steel
Which of the following waves would be suitable for sizing weld defects in underwater conditions?
Vt
Shear/Transverse waves (VT)
Particles oscillate at 90° to the wave propa
Which of the following velocities is correct for longitudinal waves within structural steels?
5940 m/s
A single probe that has a transmit and a receive crystal is known as a what
Twin crystal probe
The Cygnus DTM used for subsea applications uses what ultrasonic test system
Pulse Echo
An ultrasonic wave used subea that travels at 90 degrees to the direction of propagation is known as what?
Shear wave
Which of the following is a calibration block that contains a 23mm thick Perspex insert?
V1 block
What is displayed on the x-axis of an a-scan display unit?
Time base linearity (distance)
Note: The y-axis represents the amplitude
A diver is taking readings on the leg of a structure with a Cygnus DTM. Which of the following could prevent the diver from gaining an accurate thickness reading from the leg?
Answer: d. All of the above
a. Inclusions in the steel
b. The back wall is badly corroded
c. Poor probe contact due to localised surface pitting
d. All of the above
To accurately map out an area of thinning due to corrosion on a pipeline, which of the following instruments would be most appropriate?
A-scan ultrasonics
Fitting a lower frequency probe will?
Reduce sensitivity
Attenuation of an ultrasonic wave affects:
The amplitude of the echoed signal
The resistance to the passage of ultrasound is called:
Acoustic impedance
