How much weld should each radiograph show?

• A. 60 mm (2.4 in)
• B. 50 mm
• C. 100 mm (4 in) each spot
• D. 200 mm

Answer: (C)

In radiographic testing of welds, each exposure is intended to show a standard portion of the weld so flaws can be detected reliably and the results are comparable across spots. The established practice is to have each radiograph depict about 100 mm (4 inches) of weld. This length provides enough detail to observe typical defects along the seam while still allowing multiple exposures to cover the entire weld length with appropriate overlap. Shorter spans, like 50 or 60 mm, could leave portions of the weld unexamined, increasing the risk of missing defects. A much longer span, such as 200 mm, isn’t the standard per exposure and can complicate film handling and resolution for spotting flaws within a single spot. Therefore, showing 100 mm (4 inches) of weld per radiographic spot best aligns with inspection needs and common practice.