Liquid penetrant testing is best suited to detect discontinuities that are:

Liquid penetrant testing is best suited to detect discontinuities that are:

• A. Open to the surface
• B. Subsurface porosity not open to the surface
• C. Internal cavities
• D. Decorative surface roughness

Answer: (A)

Penetrant testing works by letting a dye or fluorescent penetrant enter any flaw that has a path to the surface, then drawing it out so an indication appears on the surface. Because the liquid relies on that surface opening to enter and exit, the method is best at revealing discontinuities that are open to the surface. Defects entirely beneath the surface, like subsurface porosity or enclosed cavities, won’t create a surface indication because there’s no surface opening for the penetrant to enter or escape. Decorative surface roughness isn’t a defect type this test targets, so it wouldn’t reliably show up as a true discontinuity in the penetrant indication.

Penetrant testing works by letting a dye or fluorescent penetrant enter any flaw that has a path to the surface, then drawing it out so an indication appears on the surface. Because the liquid relies on that surface opening to enter and exit, the method is best at revealing discontinuities that are open to the surface. Defects entirely beneath the surface, like subsurface porosity or enclosed cavities, won’t create a surface indication because there’s no surface opening for the penetrant to enter or escape. Decorative surface roughness isn’t a defect type this test targets, so it wouldn’t reliably show up as a true discontinuity in the penetrant indication.