Which statement best describes the capability of liquid penetrant testing?

Which statement best describes the capability of liquid penetrant testing?

• A. It can be used to determine material composition
• B. It can locate subsurface discontinuities
• C. It can only detect surface roughness
• D. It can locate discontinuities open to the surface

Answer: (D)

Liquid penetrant testing works by showing where a liquid that has seeped into surface openings can escape back out to the surface. When the penetrant is drawn out and a developer is applied, those openings reveal themselves as visible or fluorescent indications. This means the technique can reveal discontinuities that are open to the surface, such as cracks or seams that connect to the exterior. It won’t reliably detect discontinuities that lie entirely beneath the surface without any communication to it, and it doesn’t determine material composition or measure surface roughness. So the best description is that it locates discontinuities open to the surface.

Liquid penetrant testing works by showing where a liquid that has seeped into surface openings can escape back out to the surface. When the penetrant is drawn out and a developer is applied, those openings reveal themselves as visible or fluorescent indications. This means the technique can reveal discontinuities that are open to the surface, such as cracks or seams that connect to the exterior. It won’t reliably detect discontinuities that lie entirely beneath the surface without any communication to it, and it doesn’t determine material composition or measure surface roughness. So the best description is that it locates discontinuities open to the surface.