Which inspection method detects surface-only imperfections in brazed joints?

• A. Radiographic testing
• B. Dye penetrant testing
• C. Ultrasonic testing
• D. Magnetic particle testing

Answer: (B)

Surface-breaking flaws are most effectively revealed by dye penetrant testing. The penetrant liquid flows into any open surface openings, such as tiny cracks or porosity on the brazed joint. After removing the excess penetrant, a developer is applied, drawing the trapped penetrant back out to the surface where it forms a visible indication. This makes even small surface flaws easy to see without needing access to the opposite side or relying on internal indications. Radiographic and ultrasonic methods look inside the joint, while magnetic particle testing relies on magnetism and is limited to ferromagnetic materials; neither is as direct for surface-open defects in brazed joints. So dye penetrant testing best detects surface-only imperfections.