Non-Destructive Testing (NDT) Practice Test

What should be done to scratched, scored, and galled areas prior to magnetic particle inspection?

1. Replace the part

2. Stoned and polished with crocus cloth and oil

3. Leave them untreated

4. Apply a magnetic coating

The correct answer is: Stoned and polished with crocus cloth and oil

Prior to conducting magnetic particle inspection, it is essential to prepare the surface of the material being inspected to ensure accurate results. Scratched, scored, and galled areas can interfere with the detection of defects because they create rough surfaces that can trap particles or obscure finer indications of flaws. By stoning and polishing these affected areas with crocus cloth and oil, the surface is smoothed out, allowing for a better interaction between the magnetic particles and any potential defects present. This preparation helps remove any sharp edges and contaminants, resulting in an even and clean surface which is crucial for effective magnetic particle inspection. The process increases the likelihood of identifying true indications of discontinuities by providing a more favorable surface for the particles to adhere to. In contrast, simply replacing the part may not always be practical or necessary, and leaving the defects untreated would compromise the effectiveness of the inspection. Applying a magnetic coating is unnecessary and does not address the surface imperfections that hinder inspection quality. Thus, proper preparation of scratched, scored, and galled areas through stoning and polishing is vital for successful magnetic particle testing.