Liquid penetrant examination can detect all of the following types of discontinuities except

Liquid penetrant examination can detect all of the following types of discontinuities except

• A. Surface cracks
• B. Subsurface porosity
• C. Lack of fusion
• D. Inclusions

Answer: (B)

Liquid penetrant testing reveals flaws that have a path to the surface. The penetrant seeps into surface-breaking discontinuities and the developer draws it out to show an indication, so it’s especially good for detecting flaws that open to or are on the surface, such as surface cracks or defects like lack of fusion that reach the surface, and it can reveal flaws like inclusions if they are at or very near the surface and create a surface opening. Subsurface porosity, however, sits entirely below the surface without a connecting opening for the penetrant to enter and for the surface indication to form. Without a surface opening, the penetrant cannot reveal these voids, so subsurface porosity cannot be reliably detected by this method.

Liquid penetrant testing reveals flaws that have a path to the surface. The penetrant seeps into surface-breaking discontinuities and the developer draws it out to show an indication, so it’s especially good for detecting flaws that open to or are on the surface, such as surface cracks or defects like lack of fusion that reach the surface, and it can reveal flaws like inclusions if they are at or very near the surface and create a surface opening.

Subsurface porosity, however, sits entirely below the surface without a connecting opening for the penetrant to enter and for the surface indication to form. Without a surface opening, the penetrant cannot reveal these voids, so subsurface porosity cannot be reliably detected by this method.