Nondestructive Testing, 2. Radiography

Radiography utilizes the differential attenuation of penetrating radiation to find internal flaws such as porosity and compositional changes, as well as variations in thickness and cracks. X-rays, gamma rays, and neutrons are used and are imaged by photographic films, fluoroscopic screens, and more recently, electronic imaging devices. Thickness changes of 1-2% and flaw sizes of a few tenths of a millimeter can typically be detected. This method examines a large volume of material simultaneously, and most welds are radiographed routinely. However, radiation safety measures must be rigorously enforced.