Liquid penetrant examination is one of the most popular Nondestructive Examination NDE methods in the industry. It is economical, versatile, and requires minimal training when compared to other NDE methods. Liquid penetrant exams check for material flaws open to the surface by flowing very thin liquid into the flaw and then drawing the liquid out with a chalk-like developer. Welds are the most common item inspected, but plate, bars, pipes, castings, and forgings are also commonly inspected using liquid penetrant examination. Dye penetrant solvent removable aerosol cans. Light meter showing
Dye Penetrant Inspection
Liquid Penetrant Examination
Penetrant test is performed by cleaning the test surface thoroughly, applying coloured or fluorescent penetrant, allowing penetration time, removal of excess penetrant followed by application of developer dry or liquid form. The developer assists to draw penetrant out from the surface breaking discontinuities. After developer dwelling the test surface is examined for bleed out under natural light or black UV light depending on the type of penetrant. Dye penetrant Inspection DPI is predominantly used on non-ferrous materials in aerospace industries, shipping and offshore, petrochemical industries and stainless industry. 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.
Dye penetrant inspection
Liquid penetrant inspection is used to detect any surface-connected discontinuities such as cracks from fatigue, quenching, and grinding, as well as fractures, porosity, incomplete fusion, and flaws in joints. DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-breaking discontinuities. Penetrant may be applied to the test component by dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed, a developer is applied. The developer helps to draw penetrant out of the flaw where an invisible indication becomes visible to the inspector.
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.