How should surfaces be prepared for VT inspections?

• A. Wet and oily.
• B. Sand it down until shiny.
• C. Painted with primer.
• D. Clean, dry, and free of oils/greases and loose coatings that could obscure defects; avoid altering the surface.

Answer: (D)

Surface prep for VT inspections centers on making defects visible without introducing new features or masking them. The surface should be clean, dry, and free of oils, greases, loose coatings, or any contaminants that could obscure defects or affect how light reflects off the surface. It’s important not to alter the surface because modifications can hide flaws or create false indications.

Wet or oily surfaces would smear under inspection lighting and hide defects. Sanding until shiny changes the surface texture and can remove features or create new ones, misleading the assessment. Painting with primer adds a coating that can conceal defects and change light interaction, making VT ineffective.

So, preparing a surface that is clean, dry, free of oils/greases and loose coatings, and not altered, is the correct approach for accurate VT inspections.