What defects are likely to appear as light indications on a radiograph?

• A. Cap undercut and root piping
• B. Tungsten inclusions and excessive root penetration
• C. Slag inclusions and copper inclusion
• D. Excessive cap height and incomplete root penetration

Answer: (B)

The presence of light indications on a radiograph typically signifies areas where there is a lack of density, usually due to the inclusion of materials or irregularities within the weld. In the context of the provided choices, tungsten inclusions and excessive root penetration fit this description effectively.

Tungsten inclusions can occur when tungsten from the electrode is unintentionally introduced into the weld pool during the welding process. This creates a non-metallic defect within the weld that the radiograph captures as a lighter area because the tungsten contributes less to the overall density of the weld compared to the surrounding metal.

Excessive root penetration indicates that the molten metal has flowed deeper into the joint than intended, potentially leading to a thinner area in the weld profile. This can cause a change in the density that is detected radiographically, resulting in lighter indications.

In contrast, other defects like cap undercut, slag inclusions, and root piping are better represented in radiographs with different characteristics. For example, slag inclusions represent material that has been trapped in the weld pool, leading to denser areas as opposed to light indications. Similarly, defects such as excessive cap height or incomplete root penetration typically present themselves as variations in density that do not align with the light indications described in