Radiographic testing. Test method: LVS EN ISO 17636-1:2013. Non-destructive testing of welds - Radiographic testing - Part 1: X- and gamma-ray techniques with film
Radiography. Detection of internal defects by X-ray is based on the ability of x-rays to pass with different paths through different materials and to weaken in them depending on their thickness, type of material and radiation energy. In case of presence of cracks, pores or inclusions of foreign bodies, x-ray radiation becomes weaker.
If there is recorded distribution of radiation intensity, it is possible to determine presence of material inhomogeneity and its location.
For detecting defects of welds the radiation source (X-ray tube) is to be placed on one side of the inspected object, and on the other side - a detector (X-ray film), on which information about the defect is recorded. When radiation passes through welds, it is absorbed differently in places with defects and in places without defects: intensity of radiation at the site of the defect filled with air, gas or nonmetallic inclusions will be weakening less than in a homogeneous metal. Differences in radiation intensity are recorded by the detector, for example, the X-ray film is darkened at the location of the defect.