NDT Visual Testing Fundamentals 5 — Questions and Answers
Question 1: Which condition is a visual inspector REQUIRED to document even if it does not exceed the accept/reject criteria?
- All observations that might affect fitness for service, per the applicable code (Correct answer)
- Only defects that exceed the reject threshold
- Environmental conditions that were ideal
- Normal surface conditions with no anomalies
Correct answer: All observations that might affect fitness for service, per the applicable code
Many codes require that all relevant indications, even those within acceptance limits, be recorded for fitness-for-service trending and future comparison.
Question 2: In visual testing, 'transillumination' technique involves:
- Lighting the surface at a 45-degree angle
- Passing light through a translucent material to reveal internal variations (Correct answer)
- Using UV light to cause fluorescence
- Reflecting light off a mirror into a cavity
Correct answer: Passing light through a translucent material to reveal internal variations
Transillumination (back-lighting) shines light through thin translucent materials so internal voids, inclusions, or density variations cast visible shadows.
Question 3: What is the primary advantage of using a video borescope over a traditional fiberscope for remote visual inspection?
- Lower cost
- No image pixelation and higher resolution digital imaging (Correct answer)
- Greater insertion tube flexibility
- No need for external lighting
Correct answer: No image pixelation and higher resolution digital imaging
Video borescopes use a CCD/CMOS sensor at the tip rather than fiber bundles, eliminating the honeycomb pixelation and providing significantly higher image resolution.
Question 4: A visual inspector notices a crack that appears to run parallel to the direction of the applied stress on a pressure vessel. This orientation is:
- Less critical than a transverse crack in most cases (Correct answer)
- Always acceptable if surface-only
- More critical than a transverse crack
- Irrelevant to fitness-for-service evaluation
Correct answer: Less critical than a transverse crack in most cases
Cracks parallel to the primary stress direction are generally less critical because the stress field does not tend to open them; transverse cracks are more dangerous.
Question 5: Which type of corrosion would produce a visually uniform, even thinning over a broad surface area rather than localized pitting?
- Crevice corrosion
- Galvanic corrosion
- General (uniform) corrosion (Correct answer)
- Stress corrosion cracking
Correct answer: General (uniform) corrosion
General corrosion attacks the surface evenly across a broad area, resulting in uniform thickness loss that can be measured by comparing to original dimensions.
Question 6: What is the purpose of a 'calibrated' measuring tape or scale placed in a remote visual inspection image?
- To identify the brand of equipment used
- To provide a dimensional reference for measuring discontinuities in the image (Correct answer)
- To indicate the magnetic orientation of the part
- To certify the inspector's qualification level
Correct answer: To provide a dimensional reference for measuring discontinuities in the image
A calibrated reference scale placed adjacent to a discontinuity allows dimensional measurements to be made from the recorded image by comparison.
Question 7: Under ASNT SNT-TC-1A, the minimum hours of on-the-job training for a VT Level II candidate with no prior Level I experience is typically:
- 40 hours
- 200 hours (Correct answer)
- 400 hours
- 800 hours
Correct answer: 200 hours
SNT-TC-1A recommends 200 hours minimum on-the-job training for VT Level II certification when the candidate has not previously held Level I status.
NDT Visual Testing Fundamentals 5
Which condition is a visual inspector REQUIRED to document even if it does not exceed the accept/reject criteria?