During a visual inspection of a groove weld in a pressure vessel, a welding inspector observes several small, isolated, spherical voids on the weld surface. What NDT method would be most effective for determining the internal extent and distribution of these types of defects within the weld?

Question: During a visual inspection of a groove weld in a pressure vessel, a welding inspector observes several small, isolated, spherical voids on the weld surface. What NDT method would be most effective for determining the internal extent and distribution of these types of defects within the weld?

Answer options: ✅ Radiographic Testing (RT)

• Magnetic Particle Testing (MPT)
• Liquid Penetrant Testing (LPT)
• Ultrasonic Testing (UT)

Correct answer: Radiographic Testing (RT)

Explanation: Radiographic Testing (RT) is highly effective for detecting internal volumetric defects like porosity, as X-rays or gamma rays can penetrate the material and reveal density changes. While Ultrasonic Testing (UT) can also detect internal flaws, radiography is often preferred for porosity due to its ability to clearly image the distribution of these typically small, rounded indications. MPT and LPT are primarily surface or near-surface detection methods.