Radiographic Testing (RT)

   Radiographic Testing (RT) is a nondestructive testing (NDT) technique that involves the use of either x-rays or gamma rays to view the internal structure of a component. In the petrochemical industry, RT is often used to inspect machinery, such as pressure vessels and valves, to detect for flaws. RT is also used to inspect weld repairs.

Scientific Explanation
   Radiography is an imaging technique using X-rays, gamma rays, or similar radiation to view the internal form of an object. To create the image, a beam of X-rays or other form of electromagnetic radiation is produced by an X-ray generator and is projected toward the object. A certain amount of the X-rays or other radiation is absorbed by the object, dependent on the object’s density and structural composition. The X-rays that pass through the object are captured behind the object by a detector (either photographic film or a digital detector). The generation of flat two dimensional images by this technique is called projectional radiography.

Application Areas
   Can be used to detect expected volumetric and surface defects in all metallic or non-metallic materials.
Limitations
  The thickness of the inspection piece may not exceed certain values ​​depending on the type of radiation source to be used. Suitable material thickness ranges for various radiation sources are given in the application standards. It can be applied to all kinds of materials except the thickness limitation. The training and experience of the operator is very important. Both surfaces of the inspection piece must be accessible. The equipment used for the inspection is more expensive than other methods.

Inspection
   Various radiation sources can be used for radiographic testing. These sources may be X-ray tubes or isotopes that produce Gamma ray. The X-ray energy range used in industrial radiography is generally between 50 kV and -350 kV. The irradiation energy varies depending on the type and thickness of the material to be irradiated. The most known and used gamma sources are Ir 192, Co 60. Isotopes such as Se 75, Yb 169 Tm 170 are also used in the field of industrial radiography.