Liquid Penetrant Testing
liquid penetrant inspection (LPI) also called Dye penetrant inspection (DPI), or penetrant testing (PT), is a widely applied and low-cost inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). 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. 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.
Materials that are commonly inspected using LPI include the following:
- Metals (aluminum, copper, steel, titanium, etc.)
- Many ceramic materials