Radiography is a non-destructive testing method that can be used to detect cracks, porosity, inclusions, voids and other volumetric defects in tubular welds. Radiographic testing uses x-rays or gamma rays. The amount of energy absorbed by the weld and surround areas depends on its thickness and density. This leads to dark areas on the film where the thickness has been changes by discontinuities such as porosity or cracks. Also, low density areas, such as slag, will appear as dark areas on the film, while inclusions of high density will show up as light areas. In order to use radiography testing, it must be possible to access both sides of the weld.