Where are hole-type IQIs generally placed when using radiography to inspect steel plate?

• A. On the source side, next to the weld bead
• B. On the detector side
• C. Behind the plate
• D. Surrounding the plate

Answer: (A)

The key idea is that hole-type IQIs are used to judge the radiographic exposure and penetration by comparing known hole sizes to the weld area in the same image. Placing the IQI on the source side, right next to the weld bead, ensures the beam passes through the IQI before reaching the plate, so the IQI and the weld are subjected to essentially the same radiation field and attenuation. This makes the visible hole pattern on the radiograph a reliable reference for the weld region’s density and penetration.

If the IQI were on the detector side or behind the plate, the plate’s attenuation and scatter would alter the IQI’s image differently from the weld, making it harder to correlate the IQI readings with the weld quality. Surrounding the plate wouldn’t place the IQI in the same exposure conditions as the weld, so the reference would not be meaningful.