CWB 2 Module 19 questions with verified solutions 2023/2024 passed

CWB 2 Module 19 The upper limit of human hearing is approximately: A) 20Hz B) 20kHz C) 20MHZ - correct answer B) 20kHz A typical frequency used for ultrasonic testing of welds is: A) 2.25MHZ B) 2.25kHz C) 2.25Hz - correct answer A) 2.25MHZ Do transverse (shear) waves in a solid travel faster or slower than longitudinal (Compressional) waves? - correct answer Slower True or False? The energy carried by a wave is proportional to the square of the amplitude. - correct answer True The decrease in energy of an ultrasonic wave as it travels through a material is known as: A) Amplitude B) Amplification C) Attenuation - correct answer C) Attenuation Piezoelectric crystals can: A) Change mechanical pulses into electrical pulses B) Change electrical pulses into mechanical pulses C) Both A and B - correct answer C) Both A and B The natural frequency of a given piezoelectric transducer is determined by: A) The amplitude of the voltage applied B) The transducer thickness C) Neither of the above. The frequency is set by the material being inspected and cannot be changed. - correct answer B) The transducer thickness Name one piezoelectric material: - correct answer Quartz and lead metaniobate In conventional ultrasonics the wave is injected into the specimen as a: A) Continuous wave that the natural frequency of the transducer. B) Short pulse containing several oscillations at the natural frequency - correct answer B) Short pulse containing several oscillations at the natural frequency Why is good acoustic contact between the transducer and the test specimen needed? - correct answer Ultrasonic waves of the frequency used in inspection do not travel far in air, so good coupling between the transducer and the specimen is needed True or false? A couplant is only needed if the surface is rough - correct answer False In A-scan display the vertical displacement of the trace is calibrated to represent: A) The amplitude of the reflected wave B) The size of the reflector C) Distance - correct answer A) The amplitude of the reflected wave In A-scan display the horizontal displacement of the trace is calibrated to represent: A) The amplitude of the reflected wave B) The size of the reflector C) Distance - correct answer C) Distance In what unit is the gain control (or attenuator) marked? - correct answer dB (decibels) Which type of display gives a cross-sectional view showing the length and depth of discontinuities? - correct answer B-Scan Give an example of a system where the entire specimen is immersed in water, which acts as the couplant. - correct answer On-line examination of plate defects such as laminations in a steel mill True or False? Acoustic emission relies on detecting very small amounts of mechanical energy released from such things as growing cracks or structural discontinuities under load. - correct answer True True or False? The plate and weld surface must always be ground smooth prior to ultrasonic examination. - correct answer False Why should most ultrasonic examinations of welds begin with a search of the place with a normal probe? - correct answer To identify plate defects such as laminations that could interfere with examination of the weld with an angle probe. When using an angle probe, when should it be necessary to bounce the beam off the back wall? - correct answer Allows inspection of the upper part of weld True or False? Difficulties with UT can arise when welds have backing bars due to reflections from corners, internal reflections in the bars, etc. - correct answer True A material that may require a special technique for UT examination is: A) Carbon steel used in a pressure vessel B) Austentic stainless steel C) Structural steel for bridges - correct answer B) Austentic stainless steel True or False? The transducer in the probe always acts as both the transmitter and the receiver of the ultrasonic pulse. - correct answer False, Two separate probes could be used as the transmitter and receiver. When working to CSA W59, to what must the ultrasonic operator be certified? - correct answer CAN/CGSB-48.9712, Certification of Nondectructive Testing Personnel What two features of an angle probe can be calibrated or checked using the IIW block? - correct answer Exit point (index point) and angle Distance calibration using an IIW block for a normal (longitudinal mode) probe requires the probe to be placed on the: A) Top of the block such that the beam reflects from the 1.5mm hole B) Other edge to reflect off the curved end C) Side to reflect off the back wall - correct answer C) Side to reflect off the back wall For the transverse mode, what reflector in the IIW block is used to calibrate sensitivity according to CSA W59 - correct answer 1.5mm side hole True or False? Resolution cannot be checked because it is a function of the design of the equipment. - correct answer False What is a DAC curve? - correct answer Distance Amplitude Correction Curve. it is used to correct for the effects of attenuation. If possible one inspects most of a weld using an angle probe by: A) Using a very large probe B) Placing the probe on the weld reinforcement C) Scanning from adjacent to the weld moving in and out and along the weld. - correct answer C) Scanning from adjacent to the weld moving in and out and along the weld. As the direction of approach of the beam is changed, the amplitude of the wave reflected from a spherical probe can be expected to: A) Rise to a maximum then decrease B) Rise to a peak only if the probe were moved in the place of the plate C) Not vary significantly - correct answer C) Not vary significantly Planar discontinuities include: A) Porostiy B) Incomplete fusion