Which inspection method uses color contrast to assess the integrity of welds?

Dye penetrant inspection is a non-destructive testing method that employs a colored dye to reveal surface-breaking flaws in materials, particularly in welds. This method involves applying a penetrant to the surface of the weld. After allowing a specific dwell time for the penetrant to seep into any cracks or defects, excess penetrant is removed, and a developer is applied. The developer draws out the penetrant from the defects, creating a visible contrast against the background, which can be colored or fluorescent.

The coloring aspect of this technique allows inspectors to easily see and assess the integrity of the welds. The contrast between the dye and the surface aids in identifying flaws such as cracks, porosity, or laps. This method is especially useful in weld inspections where visual confirmation of weld integrity is critical.

While other inspection methods like ultrasonic or radiographic differ significantly in what they detect and how they present flaws, they do not primarily involve a color contrast as a means of assessment. Ultrasonic methods use sound waves to detect internal flaws, while radiographic inspection relies on X-rays or gamma rays to provide images of the internal structure, showing different density regions rather than a color contrast. Fluorescent penetrant inspection, though similar, specifically employs fluorescent dyes under UV