This is your growing NDT Question and Answer (Q&A) resource, designed to provide comprehensive explanations for both common and advanced Non-Destructive Testing (NDT) questions. We offer in-depth analysis including practical examples (if required), moving beyond basic answers to enhance your understanding of various NDT methods. To optimize your learning experience, we’ve organized questions by specific techniques, including Penetrant Testing (PT), Magnetic Particle Testing (MT), Radiographic Testing (RT), and Ultrasonic Testing (UT), among others. This ensures targeted information retrieval for specific NDT certifications and applications. We will regularly update this resource with new NDT questions and answers, keeping you abreast of the latest industry knowledge. Bookmark this page and return frequently to access the latest NDT insights and enhance your proficiency.
Penetrant Testing Question Answers
Q1. Which statement best describes the capabilities of liquid penetrant testing?
- Useful for locating subsurface flaws in a test piece
- Effective for detecting surface discontinuities in non-porous materials
- Suitable for identifying flaws in porous materials
- None of the above
Explanation: Liquid penetrant testing is effective for detecting surface discontinuities in non-porous materials. It is not suitable for subsurface flaws or porous materials, as the penetrant either won’t reach subsurface flaws or will spread uncontrollably in porous materials. Therefore, options (1), (3), and (4) are incorrect.
Q2. A penetrant process in which excess penetrant is removed with an organic solvent is called:
- Solvent removable
- Water washable
- Post-emulsified
- Dual method
Explanation: In a solvent removable penetrant process, excess penetrant is removed using an organic solvent. This method is effective for materials where water or emulsifiers cannot be used. The other options are incorrect because water washable uses water to remove excess penetrant, post-emulsified involves an emulsifier to make the penetrant water-washable, and dual method is not a standard term in penetrant testing.
Q3. How is the size of a liquid penetrant indication usually related to the discontinuity it represents:
- Larger than
- Smaller than
- Equal to
- Not related to
Explanation: The size of a liquid penetrant indication is usually larger than the actual discontinuity it represents. This is because the penetrant spreads out slightly beyond the edges of the discontinuity. The other options are incorrect because the indication is not typically smaller than, equal to, or unrelated to the size of the discontinuity.
Q4. Which penetrant method is most effective for detecting fine discontinuities?
- Solvent removable
- Water washable
- Post emulsifiable fluorescent
- Water washable fluorescent
Explanation:The most effective method for detecting fine discontinuities is post emulsifiable fluorescent. This technique uses a fluorescent dye that provides high contrast under UV light, making even the smallest discontinuities visible. Other methods are less suitable: solvent removable and water washable methods use visible dyes that may not highlight very fine discontinuities effectively, and water washable fluorescent, while more sensitive than visible dye methods, can dilute indications during washing, reducing its effectiveness.
Q5. Liquid penetrant testing is based on the principle of:
- Absorption of X rays
- Capillary action
- Polarized sound waves in a liquid
- Magnetic domains
Explanation: Liquid penetrant testing relies on capillary action, where the liquid penetrant seeps into surface-breaking defects due to its low viscosity and surface tension. The other options are incorrect because absorption of X rays is related to radiographic testing, polarized sound waves in a liquid are used in ultrasonic testing, and magnetic domains are used in magnetic particle testing.
Q6. When a small diameter tube is placed in a glass of water, water rises in the tube to a level above the adjacent surface. This is called:
- Viscosity
- Capillary action
- Surface tension
- Barometric testing
Explanation: When a small diameter tube is placed in water, the water rises in the tube due to capillary action, which is the ability of a liquid to flow in narrow spaces without the assistance of external forces. The other options are incorrect because viscosity refers to a fluid’s resistance to flow, surface tension is the elastic tendency of a fluid surface, and barometric testing is related to measuring atmospheric pressure.
Q7. Which penetrant method is most suitable for high production rates of numerous small parts?
- Solvent removable
- Water washable
- Post emulsifiable
- Fluorescent
Explanation: The best method for high production rates of many small parts is water washable. This process is efficient and quick, making it ideal for handling large volumes. Other methods are less suitable: solvent removable and post emulsifiable processes are more time-consuming due to additional cleaning steps, and fluorescent methods, while highly sensitive, may not be as fast or practical for high production environments.
Magnetic Particle Testing Question Answers
Q1. Magnetic particle testing is most effective for detecting subsurface discontinuities in:
- Soft steels with low permeability
- Hardened steels with high permeability
- Soft steels with high permeability
- Hardened steels with low permeability
Explanation: The correct answer is soft steels with high permeability. Magnetic particle testing works best on materials with high permeability because they allow magnetic fields to penetrate deeply, making subsurface discontinuities more detectable. Other options are less suitable: low permeability materials do not allow magnetic fields to penetrate as effectively, reducing the likelihood of detecting subsurface discontinuities.
Q2. The wet method is more effective than dry particles for detecting:
- Open surface cracks
- Subsurface discontinuities
- Fine surface cracks
- None of these
Explanation: The correct answer is fine surface cracks. The wet method uses smaller particles suspended in a liquid, which allows for better coverage and sensitivity, making it particularly effective for detecting very fine surface cracks
Q3. The ability of a material to remain magnetic after the magnetizing force is removed is called:
- Reluctance
- Retentivity
- Permeability
- Electromagnetism
Explanation: The correct answer is retentivity. Retentivity refers to the ability of a material to retain a certain amount of residual magnetism after the external magnetizing force has been removed. Reluctance is the opposition to the creation of a magnetic field, permeability is the ability of a material to support the formation of a magnetic field within itself, and electromagnetism is the interaction of electric currents or fields and magnetic fields.
Q4. Which of the following colors is/are commonly used for magnetic particle inspection powder?
- Red
- Gray
- Black
- All of the above
Explanation: The correct answer is all of the above. Magnetic particle test powders are commonly available in red, grey, and black, among other colors, to provide high contrast against different surfaces during inspection
Q5. Choosing the color of magnetic particle powder is based on:
- Achieving maximum contrast with the test piece background
- Optimal performance of magnetic particle/developer
- Color of inspection light available
- Best color response of the human eye
Explanation: The correct answer is achieving maximum contrast with the test piece background. This ensures that the indications are easily visible against the surface being inspected. Other factors like the performance of the particle/developer, the color of the inspection light, and the human eye’s color response are less critical in comparison
Q6. Which of the following produces a circular magnetic field?
- Coil
- Head shot
- Yoke
- All of the above
Explanation: A head shot produces a circular magnetic field around the part being tested. Coils and yokes typically produce longitudinal magnetic fields.
Q7. A leakage field is strongest when a discontinuity interrupts the magnetic flux lines at an angle of:
- Zero degrees
- 45 degrees
- 90 degrees
- 180 degrees
Explanation: The correct answer is 90 degrees. A leakage field is strongest when the discontinuity is at a right angle (90 degrees) to the magnetic flux lines, as this orientation creates the largest disruption in the magnetic field and the greatest flux leakage
Q8. A technique in magnetic particle testing where the test piece is magnetized and particles are applied after removing the magnetizing force is known as:
- Discontinuous method
- Magnetic method
- Residual method
- Continuous method
Explanation: This method involves magnetizing the test piece and then applying magnetic particles after the magnetizing force has been removed, relying on the residual magnetism to reveal discontinuities.
Q9. Which technique provides the highest sensitivity to fine surface cracks?
- Residual field, dry method
- Continuous field, wet method
- Residual field, wet method
- Continuous field, dry method
Explanation: The continuous field, wet method technique uses a continuous magnetic field and wet particles, which are smaller and more sensitive, allowing for better detection of fine surface cracks.
Q10. The prod technique is most sensitive to cracks that are:
- Tangential to a radius from each prod contact point
- Parallel to a line connecting the prod contact points
- Perpendicular to a line connecting the prod contact points
- Perpendicular to the long axis of the coil
Explanation: The correct answer is perpendicular to a line connecting the prod contact points. This orientation creates the largest disruption in the magnetic field, making the leakage field strongest and the cracks most detectable.
Q11. What is the shape of particles typically used in dry magnetic particle testing?
- Angular
- Spherical
- Mixture of elongated and globular
- Elongated
The correct answer is mixture of elongated and globular. This combination ensures good flow and sensitivity, with elongated particles aligning with magnetic flux lines and globular particles aiding in free flow and forming a cloud around the component.
For Ultrasonic Testing (UT) question answers, please click here.