ASNT UT Level 3 Questions
The ASNT UT Level III Exam is undergoing a significant structural transformation. While the number of items remains 135 questions with a 4-hour time limit, the focus is shifting from pure technical theory to high-level program management and procedural oversight.
If you are planning to sit for your exam in 2026, understanding which version of the body of knowledge (BOK) you will be tested on is critical for your preparation.
Exams Prior to 1 July 2026: The Technical Core
The current exam structure focuses heavily on the fundamental physics and application of Ultrasonic Testing. It is designed to ensure the Level III has a master-level grasp of how sound interacts with different materials and how to calibrate equipment for maximum accuracy.
- Principles and Theory: Deep dive into wave physics and propagation.
- Techniques: Heavy emphasis on comparing Contact vs. Immersion methods and remote monitoring.
- Evaluation: Focus on specific product forms like base metals, weldments, and bonded structures.
- Safety & Health: Specific questions regarding NDT-related safety protocols.
Exams After 1 July 2026: The Managerial Shift
For exams taken in the second half of 2026, ASNT is moving toward a “Managerial and Oversight” model. The new syllabus reflects the Level III’s responsibility in designing NDT programs and mentoring personnel.
- UT Training & Certification Programs: A massive new section. You must now demonstrate the ability to develop training materials, conduct testing, and manage the entire certification timeline for an organization.
- Data Interpretation & Reporting: The focus shifts to interpreting international Codes and Standards to create internal procedures.
- Equipment Management: You are now expected to manage the maintenance program, inventory, and repair cycles, rather than just performing electronic calibrations.
- Design & Validation: High-level tasks like designing UT reference standards and evaluating new, emerging UT technologies.
Summary of Changes: At a Glance
| Feature | Before July 1, 2026 | After July 1, 2026 |
| Primary Role | Advanced Technical Specialist | NDT Program Manager & Auditor |
| Methods Focus | Contact, Immersion, & Theory | Standard Design & Technique Selection |
| Personnel Role | General Knowledge | Technical Oversight & Mentorship |
| Equipment | Calibration & Functionality | Lifecycle & Inventory Management |
| Procedures | Application of Codes | Creation & Validation of New Procedures |
Prepare with Confidence
Whether you are rushing to take the exam under the current format or preparing for the new July 2026 standards, our Question Bank is being updated in real-time to reflect these changes.
Why Choose Our ASNT UT Level III Bank?
- 100% Pass Rate: Proven strategies for both the “Technical” and “Managerial” exam styles.
- Technical Mastery: Detailed explanations for wave physics, PAUT/ToFD basics, and procedure writing.
Don’t wait for the standards to change again.
ASNT UT Level III Practice Question Bank
Question 1. In an immersion testing setup for a steel component, what is the effect on the refracted shear wave angle if the water temperature in the tank increases significantly (e.g., from 20°C to 50°C)?
- A) The refracted angle in the steel will increase due to the higher acoustic impedance.
- B) The refracted angle in the steel will decrease.
- C) The refracted angle remains unchanged as temperature only affects attenuation.
- D) The shear wave velocity in the steel will decrease, causing the beam to spread.
Correct Answer: B Explanation: The velocity of sound in water increases as temperature rises (up to about 74°C). According to Snell’s Law (V1 / sin θ1 = V2 / sin θ2), an increase in the incident velocity (V1, water) while the incident angle (θ1) and steel velocity (V2) remain constant means that sin θ2 must decrease to balance the equation. Therefore, the refracted angle in the steel decreases.
Question 2. Which of the following transducer modifications will most effectively reduce the length of the near field (Fresnel zone) without altering the beam spread angle in the far field?
- A) Decreasing the transducer diameter and increasing the frequency proportionally.
- B) Increasing the frequency and keeping the piezoelectric element diameter constant.
- C) Decreasing the frequency and increasing the element diameter proportionally.
- D) Applying a highly attenuative backing material to heavily damp the crystal.
Correct Answer: A Explanation: The near field is calculated as N = D^2 / (4 * λ), and beam spread is determined by sin θ = 1.22 * λ / D. To keep the beam spread constant, the ratio of λ/D must remain constant. If you decrease the diameter (D) and decrease the wavelength (λ) by the same proportion (which means increasing the frequency), the ratio λ/D remains unchanged, keeping the beam spread constant. However, the near field formula is dominated by D^2, so reducing both proportionally will result in a shorter near field.
Question 3. When utilizing a linear phased array (PAUT) probe to steer a beam at large angles, “grating lobes” can appear and cause false indications. Under which of the following physical conditions are grating lobes most likely to be generated?
- A) When the element pitch is significantly smaller than half the wavelength of the material.
- B) When the element pitch is greater than half the wavelength and the beam is steered at large angles.
- C) When the bandwidth of the ultrasonic pulse is excessively broad.
- D) When a highly damped transducer is used in conjunction with a low-velocity wedge.
Correct Answer: B Explanation: Grating lobes are secondary main lobes created by the periodic spacing of the array elements. They occur as a result of spatial aliasing when the center-to-center distance between elements (the pitch) is larger than half of the wavelength (λ/2) of the sound wave, and their effect is severely amplified when the beam is steered at steep angles.
Question 4. The acoustic impedance of a backing material in a high-resolution piezoelectric transducer is designed to closely match the acoustic impedance of the piezoelectric crystal. What is the primary operational effect of this impedance matching?
- A) It increases the overall sensitivity and penetration power of the transducer.
- B) It minimizes internal noise, thereby improving lateral resolution.
- C) It restricts the bandwidth of the generated ultrasonic pulse to a narrow frequency range.
- D) It decreases the spatial pulse length, thereby significantly improving axial resolution.
Correct Answer: D Explanation: Matching the acoustic impedance of the backing material to the crystal allows maximum acoustic energy to be drawn out of the back of the crystal. This heavily damps the ringing of the crystal, resulting in a very short spatial pulse length and a broad bandwidth. A short pulse length is the primary factor that improves axial (depth) resolution, allowing the system to distinguish between closely spaced reflectors.
Question 5. When evaluating scattering mechanisms in polycrystalline metals (such as austenitic stainless steel welds), which relationship between ultrasonic wavelength (λ) and average grain diameter (D) characterizes the stochastic scattering regime, which is notorious for causing high noise and attenuation?
- A) The wavelength is much greater than the grain diameter (λ > 10D).
- B) The wavelength is approximately equal to the grain diameter (λ ≈ D).
- C) The wavelength is much less than the grain diameter (λ < 0.1D).
- D) The scattering is independent of wavelength and relies solely on elastic anisotropy.
Correct Answer: B Explanation: In ultrasonic testing, scattering is divided into three regimes based on the ratio of wavelength to grain size. Rayleigh scattering occurs when λ >> D (wavelength is much greater than grain size). Diffusion scattering occurs when λ << D (wavelength is much smaller). Stochastic scattering, which causes heavy attenuation and severe grass-like noise on the A-scan (common in austenitic welds), occurs when the wavelength is roughly equal to the grain size (λ ≈ D).
Question 6. During a Time of Flight Diffraction (TOFD) inspection, a “dead zone” exists near the scanning surface where near-surface defects may be masked by the lateral wave. Which of the following parameter adjustments will most effectively minimize the depth of this near-surface dead zone?
- A) Increasing the Probe Center Separation (PCS).
- B) Utilizing lower frequency transducers with wider beam divergence angles.
- C) Decreasing the Probe Center Separation (PCS) and using shorter spatial pulse lengths.
- D) Increasing the wedge delay and utilizing a longer spatial pulse length.
Correct Answer: C Explanation: The near-surface dead zone in TOFD is primarily caused by the ringing (pulse duration) of the lateral wave. To resolve defects closer to the surface, you must separate the diffracted flaw signal from the lateral wave. This is achieved by using highly damped probes (shorter pulse length/broader bandwidth) and by decreasing the Probe Center Separation (PCS), which alters the geometry to make shallow signals arrive slightly later relative to the lateral wave peak.
Question 7. When utilizing the DGS (Distance-Gain-Size) or AVG method for flaw evaluation, the technique relies on comparing the flaw’s echo amplitude to a theoretical reference. What represents the theoretical reference reflector in a standard DGS diagram?
- A) A side-drilled hole (SDH) of infinite length perpendicular to the sound beam.
- B) A perfectly reflecting flat bottom hole (FBH) acting as an ideal circular disk reflector.
- C) A spherical reflector of a known diameter placed specifically in the far field.
- D) A V-notch machined to a depth of 10% of the material thickness.
Correct Answer: B Explanation: The DGS (Distance-Gain-Size) or AVG method mathematically correlates the echo amplitude from a natural flaw to the echo amplitude of an ideal circular disk reflector at the same distance. In practice and theory, this ideal reflector is represented by a Flat Bottom Hole (FBH) whose face is perfectly perpendicular to the central axis of the ultrasonic beam.
Question 8. When attempting to generate specific Lamb wave modes (symmetrical or asymmetrical) in a thin plate, the mode generated and its phase velocity are critically dependent on which two primary factors?
- A) The acoustic impedance of the plate and the bandwidth of the transducer.
- B) The Poisson’s ratio of the wedge material and the near field length of the beam.
- C) The spatial pulse length and the distance from the transducer to the plate edge.
- D) The frequency-thickness product of the plate and the phase velocity driven by the incident angle.
Correct Answer: D Explanation: Lamb waves are highly dispersive, meaning their velocity changes depending on the frequency of the wave and the thickness of the material. The specific mode generated is dictated by the Dispersion Curves for that material, which plot phase velocity against the frequency-thickness product (f x d). To generate a specific mode, the incident angle of the wedge must be selected to match the required phase velocity according to Snell’s Law.
Question 9. In angle beam testing of a small diameter pipe weld using a standard flat wedge, the curvature of the pipe surface creates a gap that is filled with couplant. What specific effect does this have on the behavior of the transmitted sound beam?
- A) It causes the beam to diverge more rapidly in the transverse plane, reducing overall sensitivity.
- B) It acts as a converging lens, increasing the effective sensitivity at the root of the weld.
- C) It shifts the near field closer to the transducer face, improving near-surface resolution.
- D) It aligns the shear wave polarization to perfectly match the weld bevel angle.
Correct Answer: A Explanation: A flat wedge placed on a convex cylindrical surface (like a pipe) results in a wedge-to-couplant-to-steel interface where the couplant fills the outer edges more than the center. Because the velocity of sound in the couplant is much lower than in the steel, this geometry acts as a diverging cylindrical lens. This causes the beam to spread outward (diverge) more rapidly in the transverse direction, which lowers the beam’s intensity and reduces overall sensitivity.
Question 10. A flat, circular, single-element contact transducer with an active element diameter of 10 mm operates at a nominal frequency of 5 MHz. The probe is used to introduce longitudinal waves into a carbon steel component in which the longitudinal wave velocity is 5900 m/s.
Assuming the transducer behaves as an ideal, unfocused circular piston source and that material attenuation and beam distortion effects are negligible, determine the approximate axial distance from the entry surface at which the final on-axis maximum acoustic pressure (i.e., the end of the Fresnel zone) occurs.
A. 21 mm
B. 42 mm
C. 85 mm
D. 170 mm
Correct Answer: A
Explanation:
The near field length (N) for a circular transducer is given by:
N = (D² × f) / (4V)
Where:
D = 0.01 m
f = 5 × 10⁶ Hz
V = 5900 m/s
N = [(0.01)² × 5 × 10⁶] / (4 × 5900)
N ≈ 0.021 m = 21 mm
Question 11. An ultrasonic beam is transmitted from an acrylic wedge (longitudinal velocity = 2730 m/s) into carbon steel (longitudinal velocity = 5900 m/s; shear velocity = 3230 m/s). As the incident angle in the wedge is gradually increased, a condition is reached in which one refracted mode in the steel propagates parallel to the interface. At this precise incident angle, which of the following statements correctly describes the physical condition occurring in the steel?
A. The refracted shear wave is at 90 degrees
B. The refracted longitudinal wave is at 90 degrees
C. Mode conversion ceases completely
D. A Rayleigh wave is eliminated
Correct Answer: B
Explanation:
The first critical angle occurs when the refracted longitudinal wave reaches 90 degrees in the second medium. Beyond this angle, no longitudinal wave propagates into the steel; only shear waves remain.
Question 12. During calibration of a straight-beam probe intended for deep-section inspection, it is observed that two probes of identical frequency produce significantly different beam divergence angles in the far field. Assuming both probes are circular, flat, and operate in the same material under identical coupling conditions, which parameter variation would most directly explain the difference in far-field beam spread?
A. Pulse repetition frequency
B. Active element diameter
C. Couplant viscosity
D. Receiver damping setting
Correct Answer: B
Explanation:
Beam divergence angle is inversely proportional to transducer diameter and frequency. Since frequency is constant, the difference must be due to element diameter.
Question 13. While evaluating reflectors at varying metal travel distances in a pressure vessel weld, an operator constructs a reference curve by plotting echo amplitudes from side-drilled holes located at increasing depths and then uses this curve to adjust evaluation sensitivity. What fundamental acoustic phenomenon is being compensated for by this procedure?
A. Mode conversion at interfaces
B. Velocity variation within the material
C. Combined effects of attenuation and beam spreading
D. Electronic drift in the instrument
Correct Answer: C
Explanation:
Amplitude decreases with distance due to material attenuation and geometric beam spreading. The correction curve compensates for these losses.
Question 14. An ultrasonic evaluation method employs theoretical curves that relate echo amplitude, sound path distance, and equivalent reflector diameter for flat-bottom holes, allowing direct estimation of reflector size without constructing a distance-amplitude reference curve. This method is fundamentally based on which principle?
A. Empirical weld discontinuity statistics
B. Time-of-flight triangulation
C. Theoretical sound field modeling of a circular piston
D. Diffraction from crack tips
Correct Answer: C
Explanation:
The method relies on theoretical calculations of the sound field from a circular transducer and relates reflector size to amplitude and distance.
Question 15. In a weld inspection technique employing separated transmitting and receiving probes positioned on opposite sides of the weld, flaw characterization is achieved primarily through measurement of signals that originate from abrupt geometric discontinuities rather than from specular reflection off planar surfaces. Which wave phenomenon is principally responsible for detection in this configuration?
A. Specular reflection
B. Mode conversion
C. Diffraction from flaw extremities
D. Surface wave propagation
Correct Answer: C
Explanation:
The technique relies on diffraction from crack tips rather than reflection from the flaw face.
Question 16. An examination of an austenitic stainless steel weld reveals excessive structural noise and rapid decay of signal amplitude with increasing sound path, even when using lower frequencies. Which material characteristic most significantly contributes to this behavior?
A. Increased mass density
B. Coarse and anisotropic grain structure
C. Reduced acoustic velocity
D. Surface roughness at the entry point
Correct Answer: B
Explanation:
Large, anisotropic grains scatter ultrasonic energy, producing attenuation and structural noise.
Question 17. During sectorial scanning with a linear phased array probe, secondary beams of appreciable amplitude are observed at unintended angles when steering beyond a certain limit. Assuming delay laws are correctly calculated, which design parameter is most directly responsible for the formation of these undesired beams?
A. Excessive pulse duration
B. Element spacing greater than one wavelength
C. Low damping in the pulser circuit
D. Insufficient focal depth
Correct Answer: B
Explanation:
Grating lobes occur when element spacing exceeds one wavelength, producing secondary beams at predictable angles.
Question 18. While estimating the surface-connected length of a planar indication using a conventional angle beam probe, the examiner marks two probe positions corresponding to equal reductions in echo amplitude relative to the peak response and uses the separation of these positions to approximate flaw size. If the amplitude reduction selected corresponds to approximately 50% of the maximum signal height, which evaluation approach is being applied?
A. Time-of-flight separation
B. 20 dB drop method
C. 6 dB drop method
D. Diffraction-based sizing
Correct Answer: C
Explanation:
A 6 dB reduction corresponds to roughly half the signal amplitude. The distance between the -6 dB points estimates flaw length.
Question 19. A written ultrasonic examination procedure qualified for straight-beam compression wave inspection of plate material is proposed to be modified for angle-beam shear wave weld examination using different refracted angles and calibration standards. From a code compliance standpoint, how would such a modification generally be classified?
A. Administrative change
B. Editorial clarification
C. Essential variable change requiring requalification
D. Minor equipment substitution
Correct Answer: C
Explanation:
Changing from straight-beam to angle-beam inspection alters wave mode, sound path geometry, and detection capability. This constitutes an essential variable change requiring requalification.
