Liquid Penetrant Testing Level 1 (PT-1) Practice Exam

Liquid penetrant testing is primarily used to detect what type of discontinuities?

1. Subsurface defects only

2. Discontinuities open to the surface

3. Only microscopic flaws

4. Cracks found inside the material

The correct answer is: Discontinuities open to the surface

Liquid penetrant testing is primarily used to detect discontinuities that are open to the surface. This technique works by applying a penetrant to the surface of the test material; the penetrant seeps into any surface-breaking defects such as cracks, porosity, or laps. After a dwell time, excess penetrant is removed, and a developer is applied that draws the penetrant out of the defects, making them visible under UV light or white light. This method is particularly effective for detecting discontinuities such as surface cracks, which can severely impact the integrity and performance of a material or component. The nature of liquid penetrant testing limits its effectiveness for discontinuities that are subsurface or internal, as they would not be accessible for the penetrant to enter. Therefore, the focus and capability of this testing method is on surface-breaking flaws, making the choice that highlights discontinuities open to the surface the most accurate selection.