Non-Destructive Testing (NDT) Practice Test

When performing liquid penetrant inspection, which condition applies to the part under inspection?

1. It should be wet

2. It should be dry

3. It should be cold

4. All of the above

The correct answer is: All of the above

In liquid penetrant inspection, the part under inspection can actually be in various conditions as the effectiveness of the test relies on the ability of the penetrant to infiltrate any surface defects, such as cracks or voids. When it comes to the condition of the part, it should ideally be clean to remove contaminants that may inhibit the penetrant from adequately entering these defects. The term "wet" in this context refers to the application of the penetrant itself, which is a liquid that must be evenly spread over the area being inspected. The ideal situation is often that the penetrant is applied onto a surface that is prepared correctly. The part can also be dry, as any residual moisture from cleaning processes should be completely evaporated before the penetrant inspection to prevent dilution of the penetrant and ensure proper adhesion and penetration. Temperature may also play a role in the inspection process, as a cold part can assist in the penetration of the liquid into imperfections within the material. This might occur due to thermal expansion differences or simply the physical flow characteristics of the penetrant at various temperatures. Thus, stating that all conditions can apply recognizes that while a part can be "wet" during the application of the penetrant, it may need to be dry after