Calculate a radiographic technique for the circumferential steel butt weld of a pipe of outer diameter, 250mm and wall thickness 20mm. The total unsharpness for a radiographic technique is 0.2828mm. The film unsharpness is 0.2mm.  The X-ray instrument to be used has a focal spot size of 3 mm(=s) and a maximum tube current of 5mA. A density of 2 is required on the “MX” film to be used. Use 300kV and use the exposure chart in Figure 1.

Figure 1X-ray exposure chart. Film type: MX, film density 2, thin lead screens, source to film distance, sfd, 1000 mm.