Liquid Penetration

Requirements

 

Material to be inspected must be non-porous. No coatings or paint of any kind is allowed. Surface must be clean and free of any grease, oils, dirt, and other contaminants. Additional fees may apply if our technician cleans material.

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Fundamentals

 

Liquid penetrant is a surface NDE method used to detect defects open to the surface. It is primarily used for non-ferromagnetic alloys, but is equally effective on carbon and low alloy steels. It involves the application of a colored penetrating oil (red visible or yellow-green fluorescent) in the area of interest. The penetrant will be absorbed into any cracks via capillary action (works upside down equally well). After a waiting period (dwell time), the penetrant is removed (using water or solvent-dampened rags) and a developer is applied. The developer forms a white, chalky background that brings the penetrant out of the crack and alerts the technician of an imperfection.