Liquid penetrant testing (LPT Test) is one of the most widely used non-destructive testing methods. LPT test is based on capillarity or capillary attraction, where a liquid is able to flow into narrow spaces without the assistance of – or even in opposition to – external forces such as gravity.
Dye penetrant inspection (DP), also called liquid penetrate inspection (LPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to check 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.
