Liquid penetrant inspection (LPI), also referred to as dye penetrant inspection (DPI), is a widely applied non destructive testing (NDT) method used to locate surface-breaking defects in all nonporous materials. LPI is used to detect casting and forging defects, cracks, leaks in new products and fatigue cracks on in-service components.

 

DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-breaking discontinuities (Capillary action). By application of a dry powder developer the penetrant is drawn from the depth of the fissures to show as an indication on the contrasting surface. Liquid penetrant inspection can only be used to inspect for flaws that break the surface of the sample.

 

APPLICATIONS:                                       

• Metals (aluminum, copper, steel, titanium, etc.)

• Glass

• Many ceramic materials

• Rubber

• Plastics

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SOME OF THESE FLAWS ARE LISTED BELOW:                                       

• Fatigue cracks

• Quench cracks

• Grinding cracks

• Overload and impact fractures

• Porosity

• Laps

• Seams

• Pin holes in welds

• Lack of fusion or braising along the edge of the bond line