1. What is the main function of a calibration block in ultrasonic testing?
a) To amplify the signal strength
b) To provide standard reflectors for setting sensitivity and range
c) To minimize sound wave scattering
d) To replace the need for a coupling medium
Answer: b) To provide standard reflectors for setting sensitivity and range
Explanation: Calibration blocks contain known reflectors (e.g., side-drilled holes) to adjust the UT system for accurate distance and sensitivity measurements.
2. The near-field distance of a round UT transducer is influenced by:
a) The density of the test material
b) The transducer’s size, frequency, and the material’s sound velocity
c) The thickness of the couplant layer
d) The angle of the sound beam
Answer: b) The transducer’s size, frequency, and the material’s sound velocity
Explanation: The near-field length is determined by the formula N = D²f / (4v), where D is the transducer diameter, f is frequency, and v is velocity.
3. Where is the focal point of a focused ultrasonic transducer typically located?
a) In the far-field region
b) At the transducer’s surface
c) Within the near-field zone
d) Past the test material’s thickness
Answer: c) Within the near-field zone
Explanation: A focused transducer concentrates the beam at a specific point, usually in the near field, to improve resolution at that depth.
4. The bending of ultrasonic waves at a boundary due to a velocity change is known as:
a) Diffraction
b) Refraction
c) Dispersion
d) Absorption
Answer: b) Refraction
Explanation: Refraction occurs when sound waves cross a boundary between materials with different velocities, governed by Snell’s law.
5. Per SNT-TC-1A, what is a primary duty of a UT Level III professional?
a) Conducting all on-site inspections
b) Creating and validating inspection procedures
c) Managing equipment maintenance logs
d) Performing routine gain adjustments
Answer: b) Creating and validating inspection procedures
Explanation: A Level III is tasked with developing, reviewing, and approving procedures to ensure compliance with applicable standards.
6. Increasing the frequency of a UT transducer typically results in:
a) Greater penetration depth
b) Enhanced resolution with less penetration
c) No change in resolution or depth
d) Wider beam spread
Answer: b) Enhanced resolution with less penetration
Explanation: Higher frequencies produce shorter wavelengths for better resolution but increase attenuation, reducing penetration.
7. In angle-beam weld testing, mode conversion occurs when:
a) The beam reflects off the opposite surface
b) A shear wave partially transforms into a longitudinal wave at a boundary
c) The beam scatters within the material
d) The couplant is unevenly applied
Answer: b) A shear wave partially transforms into a longitudinal wave at a boundary
Explanation: Mode conversion happens when an angled shear wave hits an interface, generating a longitudinal wave component.
8. How can the signal-to-noise ratio be improved in ultrasonic testing?
a) Lowering the receiver gain
b) Using a lower-frequency transducer
c) Adjusting the receiver bandwidth and applying filters
d) Increasing the pulse repetition frequency
Answer: c) Adjusting the receiver bandwidth and applying filters
Explanation: Optimizing bandwidth and filtering reduces background noise while preserving the defect signal.
9. What is the purpose of a Distance Amplitude Correction (DAC) curve in UT?
a) To correct for material attenuation and beam divergence
b) To filter out non-relevant indications
c) To set the transducer’s angle
d) To stabilize the pulser output
Answer: a) To correct for material attenuation and beam divergence
Explanation: A DAC curve adjusts gain to ensure consistent sensitivity for reflectors at varying depths.
10. In phased array ultrasonic testing, what controls the direction of the sound beam?
a) The size of the transducer array
b) Time delays applied to individual elements
c) The test material’s acoustic properties
d) The type of couplant used
Answer: b) Time delays applied to individual elements
Explanation: Beam steering in phased array systems is achieved by varying the timing of element activation.
11. A major challenge when inspecting coarse-grained materials is:
a) Weak initial pulse signals
b) Strong backwall reflections
c) Increased scattering and sound loss
d) Absence of shear wave generation
Answer: c) Increased scattering and sound loss
Explanation: Coarse grains cause scattering, which increases attenuation and obscures defect signals.
12. The critical angle for a shear wave in steel (velocity ~3,200 m/s) at a water (velocity ~1,480 m/s) interface is approximately:
a) 27.5°
b) 35.0°
c) 45.0°
d) 55.0°
Answer: a) 27.5°
Explanation: Using Snell’s law (sin θc = v1/v2), θc = arcsin(1,480/3,200) ≈ 27.5°.
13. What is a key benefit of the Time of Flight Diffraction (TOFD) technique?
a) High sensitivity to near-surface flaws
b) Precise defect sizing regardless of orientation
c) No need for a coupling medium
d) Faster scans for thick sections
Answer: b) Precise defect sizing regardless of orientation
Explanation: TOFD uses diffracted waves to accurately size defects, independent of their alignment.
14. A UT calibration block should:
a) Be made from a different material than the test object
b) Have acoustic properties similar to the test material
c) Avoid any machined surfaces
d) Be larger than the test object
Answer: b) Have acoustic properties similar to the test material
Explanation: Matching acoustic properties ensures the calibration reflects the test material’s behavior.
15. The 6 dB drop technique is primarily used to:
a) Measure the depth of a flaw
b) Estimate the size of a planar defect
c) Determine the material’s sound velocity
d) Fine-tune the system gain
Answer: b) Estimate the size of a planar defect
Explanation: The 6 dB drop method involves scanning to map a defect’s boundaries based on signal amplitude reduction.
16. When performing immersion testing, the water path distance affects:
a) The transducer’s frequency
b) The time-of-flight to the test surface
c) The material’s attenuation
d) The beam’s angle in the material
Answer: b) The time-of-flight to the test surface
Explanation: The water path adds to the total time-of-flight, requiring adjustment in calibration.
17. In a UT procedure, the minimum number of calibration reflectors is determined by:
a) The transducer’s diameter
b) The required depth range and accuracy
c) The couplant viscosity
d) The test material’s thickness only
Answer: b) The required depth range and accuracy
Explanation: Reflectors are chosen to cover the inspection depth range and ensure precise calibration.
18. A high damping setting on a transducer is used to:
a) Increase the pulse energy
b) Shorten the pulse duration for better resolution
c) Reduce the beam’s focus
d) Enhance penetration in thick materials
Answer: b) Shorten the pulse duration for better resolution
Explanation: High damping reduces ringing, producing a shorter pulse for improved near-surface resolution.
19. What factor most affects the beam spread of a UT transducer?
a) The material’s density
b) The transducer’s frequency and diameter
c) The pulser voltage
d) The test surface curvature
Answer: b) The transducer’s frequency and diameter
Explanation: Beam spread is governed by the wavelength (frequency) and transducer size, with higher frequencies reducing divergence.
20. In a pitch-catch UT setup, the primary advantage is:
a) Reduced need for calibration
b) Improved detection of planar defects perpendicular to the beam
c) Elimination of backwall echoes
d) Increased penetration depth
Answer: b) Improved detection of planar defects perpendicular to the beam
Explanation: Pitch-catch uses separate transmitter and receiver, enhancing sensitivity to defects aligned with the beam path.
21. The primary source of attenuation in ultrasonic testing is:
a) Beam reflection
b) Scattering, absorption, and beam spread
c) Couplant mismatch
d) Transducer wear
Answer: b) Scattering, absorption, and beam spread
Explanation: Attenuation results from energy loss due to scattering, absorption in the material, and beam divergence.
22. When qualifying a UT procedure, what is essential?
a) Using the smallest available transducer
b) Demonstrating the ability to detect specified flaws
c) Testing only the thinnest material section
d) Avoiding reference blocks
Answer: b) Demonstrating the ability to detect specified flaws
Explanation: Qualification requires proving the procedure can reliably detect and size defects per the standard.
23. In phased array UT, a sectorial scan refers to:
a) A fixed-angle scan at maximum gain
b) A sweep of the beam through a range of angles
c) A linear scan along the transducer axis
d) A scan with reduced pulse repetition
Answer: b) A sweep of the beam through a range of angles
Explanation: Sectorial scans sweep the beam across an angular range to cover a broader inspection area.
24. The purpose of a couplant in UT is to:
a) Amplify the ultrasonic signal
b) Reduce transducer wear
c) Facilitate sound transfer between transducer and material
d) Cool the test surface
Answer: c) Facilitate sound transfer between transducer and material
Explanation: Couplant minimizes air gaps, allowing efficient sound transmission into the test material.
25. When inspecting a curved surface, what adjustment may be needed?
a) Increase the transducer frequency
b) Use a contoured wedge or shoe
c) Decrease the pulser voltage
d) Eliminate the DAC curve
Answer: b) Use a contoured wedge or shoe
Explanation: A contoured wedge ensures proper contact and sound coupling on curved surfaces.
26. In UT, a dead zone is caused by:
a) Low-frequency transducers
b) The initial pulse and transducer ringing
c) Excessive couplant thickness
d) High material attenuation
Answer: b) The initial pulse and transducer ringing
Explanation: The dead zone is the region near the surface where defect detection is obscured by the initial pulse.
27. What is a limitation of using a dual-element transducer?
a) Inability to detect near-surface flaws
b) Reduced sensitivity to deep flaws
c) Increased beam spread
d) Requirement for immersion testing
Answer: b) Reduced sensitivity to deep flaws
Explanation: Dual-element transducers are optimized for near-surface detection but lose sensitivity at greater depths.
28. The acceptance criteria for a UT inspection are typically based on:
a) The transducer’s frequency
b) The applicable code or standard
c) The operator’s experience
d) The couplant type
Answer: b) The applicable code or standard
Explanation: Acceptance criteria are defined by standards (e.g., ASME, API) specific to the application.
29. When setting up a TOFD inspection, the probe separation is critical because it:
a) Determines the transducer frequency
b) Affects the coverage and depth resolution
c) Eliminates the need for a DAC curve
d) Reduces the water path distance
Answer: b) Affects the coverage and depth resolution
Explanation: Proper probe separation ensures optimal detection of diffracted signals across the inspection volume.
30. In a UT report, what must be documented?
a) Only the transducer serial number
b) Inspection parameters, results, and calibration details
c) The operator’s training records
d) The test material’s chemical composition
Answer: b) Inspection parameters, results, and calibration details
Explanation: A complete report includes all relevant data, such as equipment settings, findings, and calibration records, per standard requirements.
1. What is the primary role of a standardization block in ultrasonic testing?
a) To enhance signal clarity
b) To establish reference points for calibration of range and sensitivity
c) To reduce material attenuation
d) To eliminate surface reflections
Answer: b) To establish reference points for calibration of range and sensitivity
Explanation: Standardization blocks provide known reflectors to set up the UT system for accurate depth and amplitude measurements.
2. The length of the near field for a flat transducer is determined by:
a) The material’s grain structure
b) The transducer’s diameter, frequency, and the material’s acoustic velocity
c) The type of couplant applied
d) The test piece’s surface finish
Answer: b) The transducer’s diameter, frequency, and the material’s acoustic velocity
Explanation: The near-field length is calculated using N = D²f / (4v), where D is diameter, f is frequency, and v is velocity.
3. In a focused beam UT setup, the focal zone is generally located:
a) Beyond the near field
b) At the transducer’s contact surface
c) Inside the near-field region
d) At the material’s back wall
Answer: c) Inside the near-field region
Explanation: Focused transducers concentrate energy at a point within the near field to optimize resolution at a specific depth.
4. The change in direction of sound waves due to a velocity difference at a boundary is called:
a) Scattering
b) Refraction
c) Diffraction
d) Absorption
Answer: b) Refraction
Explanation: Refraction occurs when sound waves cross media with different velocities, following Snell’s law.
5. According to ASNT SNT-TC-1A, a UT Level III is primarily responsible for:
a) Conducting all inspections personally
b) Designing and approving inspection techniques
c) Maintaining daily calibration logs
d) Selecting couplant types
Answer: b) Designing and approving inspection techniques
Explanation: A Level III develops, validates, and authorizes procedures to meet technical and regulatory requirements.
6. What happens when the frequency of a UT transducer is increased?
a) Penetration depth increases
b) Resolution improves, but penetration decreases
c) Beam angle widens
d) No effect on inspection quality
Answer: b) Resolution improves, but penetration decreases
Explanation: Higher frequencies reduce wavelength for better resolution but increase attenuation, limiting penetration.
7. During angle-beam testing of welds, mode conversion is observed when:
a) The beam reflects from a defect
b) A shear wave transforms partially into a longitudinal wave at an interface
c) The couplant layer is too thin
d) The beam scatters in the weld zone
Answer: b) A shear wave transforms partially into a longitudinal wave at an interface
Explanation: Mode conversion occurs at boundaries, creating a longitudinal wave from an incident shear wave.
8. To enhance the signal-to-noise ratio in UT, one should:
a) Increase the pulse repetition rate
b) Optimize receiver filtering and bandwidth settings
c) Lower the transducer frequency
d) Reduce the gain control
Answer: b) Optimize receiver filtering and bandwidth settings
Explanation: Proper filtering minimizes noise while retaining defect signals, improving clarity.
9. The purpose of a Time Gain Compensation (TGC) curve is to:
a) Adjust the transducer’s beam angle
b) Correct for signal loss due to distance and attenuation
c) Eliminate non-relevant echoes
d) Standardize the pulser output
Answer: b) Correct for signal loss due to distance and attenuation
Explanation: TGC adjusts gain to maintain consistent amplitude for reflectors at different depths.
10. In phased array UT, beam focusing is achieved by:
a) Increasing the transducer size
b) Applying specific time delays to array elements
c) Changing the test material’s velocity
d) Using a thicker couplant layer
Answer: b) Applying specific time delays to array elements
Explanation: Time delays control the constructive interference of waves, focusing the beam at a desired point.
11. Inspecting materials with large grains often results in:
a) Overly strong backwall signals
b) High scattering and reduced signal quality
c) Improved defect resolution
d) No effect on inspection
Answer: b) High scattering and reduced signal quality
Explanation: Large grains scatter sound waves, increasing attenuation and complicating defect detection.
12. The critical angle for a shear wave in steel (velocity ~3,250 m/s) at a plastic wedge (velocity ~2,700 m/s) interface is closest to:
a) 56.2°
b) 48.7°
c) 39.5°
d) 65.0°
Answer: a) 56.2°
Explanation: Using Snell’s law, sin θc = v1/v2 = 2,700/3,250, so θc ≈ arcsin(0.83) ≈ 56.2°.
13. A significant advantage of Time of Flight Diffraction (TOFD) is:
a) High sensitivity to surface-breaking cracks
b) Accurate defect height measurement regardless of orientation
c) No requirement for calibration blocks
d) Faster inspection of small parts
Answer: b) Accurate defect height measurement regardless of orientation
Explanation: TOFD uses diffraction signals to size defects precisely, independent of their angle.
14. For UT calibration, the reference block must:
a) Differ in composition from the test material
b) Have acoustic properties matching the test material
c) Be free of any reflectors
d) Be thicker than the test piece
Answer: b) Have acoustic properties matching the test material
Explanation: Similar acoustic properties ensure calibration reflects the test material’s sound behavior.
15. The 20 dB drop method in UT is typically used to:
a) Calculate material velocity
b) Size large planar defects
c) Adjust the time base
d) Set the initial gain
Answer: b) Size large planar defects
Explanation: The 20 dB drop method maps defect boundaries by noting significant amplitude reductions during scanning.
16. In immersion UT, the water path primarily affects:
a) The transducer’s beam width
b) The travel time to the test material’s surface
c) The material’s grain size
d) The defect’s orientation
Answer: b) The travel time to the test material’s surface
Explanation: The water path adds to the time-of-flight, requiring calibration adjustments.
17. The number of reflectors in a UT calibration block depends on:
a) The transducer’s frequency range
b) The inspection depth and precision requirements
c) The couplant’s acoustic impedance
d) The test piece’s surface condition
Answer: b) The inspection depth and precision requirements
Explanation: Reflectors are selected to span the inspection range and ensure accurate setup.
18. A low-damping transducer is best suited for:
a) High-resolution near-surface testing
b) Deep penetration in thick materials
c) Reducing beam spread
d) Eliminating mode conversion
Answer: b) Deep penetration in thick materials
Explanation: Low damping produces a longer pulse, increasing energy for better penetration.
19. The divergence of a UT beam is most influenced by:
a) The material’s thickness
b) The transducer’s frequency and size
c) The receiver gain setting
d) The surface preparation
Answer: b) The transducer’s frequency and size
Explanation: Beam spread depends on wavelength (frequency) and transducer dimensions, with higher frequencies reducing divergence.
20. In a tandem UT setup, the main benefit is:
a) Simplified calibration
b) Enhanced detection of vertical planar flaws
c) Reduced inspection time
d) Elimination of surface waves
Answer: b) Enhanced detection of vertical planar flaws
Explanation: Tandem setups use separate transmitter and receiver to target defects perpendicular to the beam.
21. The primary cause of signal loss in UT is:
a) Transducer misalignment
b) Absorption, scattering, and beam divergence
c) Improper gain settings
d) Couplant evaporation
Answer: b) Absorption, scattering, and beam divergence
Explanation: These factors reduce signal strength through energy dissipation and spreading.
22. To qualify a UT procedure, it is critical to:
a) Use a single transducer size
b) Verify detection of specified defects
c) Limit testing to thin sections
d) Avoid reference standards
Answer: b) Verify detection of specified defects
Explanation: Qualification demonstrates the procedure’s ability to meet detection and sizing requirements.
23. In phased array UT, a linear scan involves:
a) Sweeping the beam across multiple angles
b) Moving the beam along the array’s axis at a fixed angle
c) Increasing the pulse rate
d) Reducing the focal depth
Answer: b) Moving the beam along the array’s axis at a fixed angle
Explanation: Linear scans translate the beam along the transducer array for consistent angle coverage.
24. The couplant’s role in UT is to:
a) Increase signal amplitude
b) Protect the transducer surface
c) Enable efficient sound transmission into the material
d) Stabilize the test temperature
Answer: c) Enable efficient sound transmission into the material
Explanation: Couplant reduces air gaps, ensuring sound waves enter the test material effectively.
25. Inspecting a cylindrical component may require:
a) A higher-frequency transducer
b) A specially shaped wedge for proper contact
c) A reduced gain setting
d) No calibration block
Answer: b) A specially shaped wedge for proper contact
Explanation: A contoured wedge ensures good coupling on curved surfaces.
26. The near-surface dead zone in UT results from:
a) High material attenuation
b) The initial pulse and transducer ringing
c) Low-frequency settings
d) Thin couplant layers
Answer: b) The initial pulse and transducer ringing
Explanation: The dead zone obscures near-surface defects due to the initial pulse’s interference.
27. A disadvantage of a single-element transducer compared to phased array is:
a) Limited penetration depth
b) Inability to steer or focus the beam dynamically
c) Increased setup time
d) Reduced signal amplitude
Answer: b) Inability to steer or focus the beam dynamically
Explanation: Single-element transducers have fixed beam properties, unlike phased arrays.
28. UT acceptance criteria are generally defined by:
a) The operator’s judgment
b) The governing code or specification
c) The transducer’s specifications
d) The test material’s properties
Answer: b) The governing code or specification
Explanation: Standards like ASME or AWS provide specific criteria for evaluating indications.
29. In TOFD setup, the probe center spacing (PCS) is critical because it:
a) Sets the transducer frequency
b) Influences defect coverage and resolution
c) Determines the couplant thickness
d) Eliminates backwall signals
Answer: b) Influences defect coverage and resolution
Explanation: PCS affects the region inspected and the clarity of diffracted signals.
30. A UT inspection report must include:
a) Only the defect locations
b) Equipment settings, findings, and calibration details
c) The transducer’s manufacturing date
d) The test material’s weight
Answer: b) Equipment settings, findings, and calibration details
Explanation: Comprehensive reporting ensures traceability and compliance with standards.
