Non destructive testing liquid penetration
Dye penetrant inspection (DPI), also called liquid penetrate inspection (LPI) 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 .
ISO , Non-destructive testing - Penetration testing and magnetic particle.
Liquid penetrant inspection
Description:Some of the common parts tested are stainless steel welded joints, aluminium alloys joints, turbine blades, stainless steel fittings, castings and forgings, weld overlays stellite , aerospace engine parts, etc. Experience showed that temperature and soak time were important. Ultraviolet UV-A radiation of adequate intensity 1, micro-watts per centimeter squared is common , along with low ambient light levels less than 2 foot-candles for fluorescent penetrant examinations. The principle of liquid penetrant testing is that the liquid penetrant is drawn into the surface-breaking crack by capillary action and excess surface penetrant is then removed; a developer typically a dry powder is then applied to the surface, to draw out the penetrant in the crack and produce a surface indication. Several developer types are available, including: