Non-Destructive Testing (NDT) Practice Test

What is the recommended motion for applying developer during a fluorescent penetrant inspection?

1. Circular motion

2. Back and forth motion

3. One direction motion

4. Random motion

The correct answer is: One direction motion

In fluorescent penetrant inspection, the recommended motion for applying the developer is a one-direction motion. This method ensures that the developer is evenly distributed across the surface of the part being inspected, which is crucial for creating a consistent and visible fluorescent indication of any surface-breaking discontinuities. Using a one-direction motion helps to prevent the developer from being smeared or agitated excessively, thereby allowing it to effectively absorb any excess penetrant that might still be present. This is important because the purpose of the developer is to draw penetrant out from any defects into the developer layer, making them more visible under UV light. If the application of the developer is erratic or random, it could lead to uneven coverage and potentially obscure the indications that the inspection seeks to reveal. Additionally, this technique also minimizes the risk of trapping air bubbles beneath the developer, which can interfere with the viewing of penetrant indications. A controlled application promotes better penetration into any cracks or flaws, enhancing the reliability of the inspection results.