What type of defects do lighter spots on a radiograph typically indicate?

Lighter spots on a radiograph commonly indicate the presence of spatter. In radiographic testing, spatter refers to small droplets of molten metal that have been expelled during the welding process and subsequently solidified on the base material or within the weld bead. These spatter droplets often have a different density compared to the surrounding material. As a result, when a radiograph is produced, these areas appear lighter due to the lower absorption of X-rays or gamma rays.

This interpretation is crucial for weld quality assessments as spatter can impact the overall integrity and performance of the weld, even though it may not pose the same risks as other defects. Understanding how to interpret these lighter spots is essential for weld inspectors to provide accurate evaluations of welding quality and take any necessary corrective actions. In contrast, defects such as slag, porosity, and weld overlap would present differently on a radiograph, leading to different visual cues that would not manifest as lighter spots.