The penetrant may be applied to all non-ferrous materials and ferrous materials, although for ferrous components magnetic-particle inspection is often used instead for its subsurface detection capability. Liquid Penetrant Inspection (LPI) is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks on in-service components. Fluorescent dye can be used for intricate parts.
- Liquid Penetrant Inspection is a very sensitive method, capable of finding extremely fine flaws.
- It can be used on magnetic and non-magnetic metals, some plastics and glass.
- Small objects, with awkward shapes, can be inspected.