X-rays are the electromagnetic waves or photon beams with wavelength between 10 and 0,01 nm, equivalent to or between 0.125 - 125 keV energy range.
The radiographic test (RT) or the industrial x-ray is a non-destructive test method.
This method is used for the ferromagnetic and non-ferromagnetic metals as well as other materials. X rays do not harm the material and allow us to examine the internal structure of the materials, therefore they are commonly used for the non-destructive examination tests. X or gamma rays are used to determine the material thickness changes, structural changes, internal faults and assembly details.
The gamma rays radiating from the radioactive isotopes and the x-rays that are electrically produced, are absorbed by the material through which they pass. The absorbed amount is increased in parallel with the thickness. Therefore the denser materials absorb higher radiation amounts.
Similar to the light, x and gamma rays belong to the electromagnetic wave group. The only difference they have is their wavelengths. X and gamma rays have lower wavelengths therefore they cannot be seen and they can bore the materials. X and gamma rays have the same properties as the light; they turn the silver crystals into metallic silver on the films and the image is created depending on the density of the radiation that reaches the film.
The most basic rule of the industrial radiography is to have the source of the beam at one side of the material, and the detector on the other side. X or gamma ray sources are used as the radiation source while the film is used as the detector. The radiation weld energy shall be chosen at a power level that can bore the material. The boring power of the energy is determined by the wavelength. The slower the wavelength, the bigger the boring power is. The boring power of the X rays in X ray radiography is adjusted by the voltage applied to the X-ray tube. Approximately 1000 volt of power is required for the thickness of steel per inch. The isotope determines the boring power in scope of the gamma radiography and it is impossible to be changed for each isotope. Iridium 192 is used for the steels between ½” and 1” while cesium 134 is used for steels between ¾” and 2 ½”. The film that detects the beams which reach the opposite end by boring the material is generally placed at the rear side of the tested material by being placed within an envelope resistant to the light. The main rule here is to ensure that the front face of the envelope must be made of material that can be easily passed by the beams.