Radiographic examination method is a non-destructive type of examination using known x-ray technique. The radiation used during the radiography examination is low-wavelength and high-energy electromagnetic waves. The necessary radiation is provided using the X-ray tube. The material to be examined is placed between the radiation source and the film piece. Thicker and denser areas within the material will block more radiation.
High-energy electromagnetic waves can pass through many materials and affect the radiation-sensitive films behind them. After washing these films, an image of the inner parts of the material through which radiation is exposed is revealed. With this method, gaps or density changes in the material are monitored on the film. This imaging phenomenon is called radiography and the evaluation using this method is called radiographic examination. There is also a radioscopy method similar to this method. If a detector is placed on the back of the material, not a film, the radiation passing through the material is collected and sent to a monitor, this method is called radioscopy. Both methods are similar but the outputs are different.
There are three main factors that affect radiation intensity in radiographic examination. These are the type, thickness and wavelength of the radiation used. If a strong beam is sent onto a sheet of iron of a certain thickness, the beam passes to the other side of the plate with a slight weakening of the intensity. Therefore, different sources of radiation are used for radiographic examination. These sources are X-ray tubes or gamma-ray-producing isotopes. More X-ray tubes are used in the industry. Irradiation energy varies according to the type and thickness of the material to be examined.
Standards for Radiographic Examination
Radiographic method is used to detect surface or internal defects of certain parts and materials of certain thickness. The radiographic examination method, which allows the material to be checked and inspected without being destroyed, is used to detect volumetric errors in any kind of material that is not too thick metallic or non-metallic. The main disadvantage of radiographic examination, which is generally unsuitable for parts that are too thick, is that it is harmful to human health.
Today, there are many test and inspection institutions that apply and evaluate radiographic examination methods. What is important is that these studies are carried out by mechanical engineers having RT9712 and RT7477 certificates in compliance with TS EN ISO 473 Nondestructive testing - NDT personnel qualification and certification - General specifications standard (previous TS 1 EN 2 standard).
In order to ensure reliable and healthy results of radiographic examinations, procedures should be performed in accordance with standards. These standards are prepared according to the material type. The standards used in the application of radiographic examination technique are as follows:
- TS EN ISO 5579 Non-destructive testing - Radiographic examination of metallic materials by film and X- or gamma rays - General requirements (previous EN 444 standard)
- TS EN ISO 19232-1 Non-destructive testing - Image quality of radiographs - Part 1: Image quality indicators (wire type) - Determination of image quality value (previous EN 461-1 standard)
- TS EN ISO 19232-2 Non-destructive testing - Part 2: Image quality indicators (step / hole type) - Determination of image quality value (previous EN 461-2 standard)
- TS EN ISO 19232-3 Non-destructive testing - Part 3: Image quality classes (previous EN 461-3 standard)
- TS EN ISO 19232-4 Non-destructive testing - Image quality of radiographs-Part 4: Image quality values and evaluation of image quality charts by experiment (previous EN 461-4 standard)
- TS EN ISO 19232-5 Non-destructive testing - Part 5: Image quality indicators (double-wire type) - Determination of the total image half-shadow value (previous EN 461-5 standard)
- TS EN 12681 Castings - Radiographic examination
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