Which method is typically used to inspect surfaces for cracks and discontinuities?

Penetrant testing is specifically designed to detect surface cracks and discontinuities in non-porous materials. This method involves applying a liquid penetrant to the surface of the material, allowing it to seep into any surface-breaking flaws. After a defined dwell time, any excess penetrant is removed, and a developer is applied to draw the penetrant out of the defects, creating a visible indication of any discontinuities present.

This process is particularly effective for identifying tiny cracks, as it can reveal defects that are not immediately visible to the naked eye. Therefore, penetrant testing is one of the primary non-destructive testing methods used for detecting surface flaws, making it highly relevant for ensuring the integrity of components in various industries.

Other methods like visual testing, while important for initial examinations, rely on direct observation and may miss smaller or less apparent flaws. Ultrasonic testing and radiographic testing are geared toward detecting subsurface defects, making them less suitable for the specific purpose of inspecting surfaces for visible cracks and discontinuities compared to penetrant testing.