Non-Destructive Testing (NDT) Practice Test

What might be required if the surface of a part has been machined, surface blasted, filed, or sanded?

1. Cleaning only

2. Replacement of the part

3. Etching of the part

4. Repainting for protection

The correct answer is: Etching of the part

When a part's surface has been machined, surface blasted, filed, or sanded, these methods can alter the surface finish and potentially create areas that are more susceptible to corrosion or other types of damage. In such cases, etching is often required to ensure proper surface preparation before further processing, such as coating or welding. Etching helps to create a more conducive surface profile by removing any contaminants and creating an ideal roughness for adhesion. This is particularly important when you want to enhance bonding with subsequent treatments like coatings or paints. By achieving an appropriate surface condition, etching helps to ensure the longevity and performance of the part during its use. In contrast, simply cleaning the part may not be sufficient if the surface has been adversely affected by machining or blasting. While cleaning prepares the surface to some extent, it does not address the need for ideal surface characteristics that etching provides. Replacement may be excessive unless the part is found to be defective beyond repair, while repainting does not address the critical surface condition necessary for effective protection and performance. Thus, etching is the correct approach for a part with surface modifications that need to be addressed for optimal functionality.