Radiography Testing or X ray Testing:
Radiography Testing uses electromagnetic radiation from a source to capture image of the object. The source used may be gamma radiation emitting source or an X ray emitting source. Either of the radiation have capability of penetrating into matter so that even an internally located defect’s image is captured.
How is Radiography Image captured?
The radiation penetrating into the object is made to fall on a detector; the detector may be a photosensitive film, a Phosphor plate, or a semiconductor flat panel.
The image density formed on the film is directly proportional to the amount of radiation fall on it. Where ever the radiation falls directly on film the image is darker, when radiation passes through an object before reaching the film, radiation gets absorbed in the object and forms a lighter image on the film. The rate of absorption depend on the atomic number of the object material and thickness of the object.
Therefore if a material of different atomic number or a void pace is present in the object. There will be difference in radiation absorption (attenuation) and thus there will be different image density on the film. Thus a defect is identified.
Advantages of X-ray or Radiography Testing
- The method can be used for any material (metal or non Metals)
- RT or X-ray can detect defects located in any location (surface, sub Surface, or Internally)
- RT or X-ray (Film or Digital) can produce a permanent record, where defects if any can be identified by everyone
- There are advanced Radiography methods like Digital radiography and Computed Tomography, where defect identification will be rapid and a dimensional view of the defect is possible for detailed analysis.
How will Film radiographic images look like?
Film radiography has to be stored physically.
How will digital radiography images look like ?
Digital Radiography can be stored in a computer and shared digitally, can be printed down when required.
What will be the cost of Radiography Testing?
The cost of conventional Film radiography is generally calculated based on the surface area of the scanned object. Generally, the total size of the radio-graphic film used is charged. The charge may vary from Rs.6 per square inch up to Rs.15 per Square inch, depending upon the criticality and type of source used for scanning.
The cost of digital radiography is calculated based on the time taken for scanning the object.