What is Radiographic testing?
Radiographic Testing (RT) is a non-destructive testing (NDT) method which uses either x-rays or gamma rays to examine the internal structure of manufactured components identifying any flaws or defects.
Types of Radiographic testing?
1) X -Ray Radiography
2) Gamma Ray Radiography
Advantages of Radiographic testing?
There are many advantages to radiography, including:
- Inspection capability for many types of material with varying density
- Ability to inspect assembled components
- Minimal surface preparation required
- Determination of crack growth
- Detection of both surface and subsurface defects
- Permanent record of the inspection
Different Between X Ray & Gamma Ray
The gamma rays and X-rays are the types of electromagnetic radiation. Generally some of the basic properties of the X-rays and gamma rays are kind of similar. X-rays are emitted by the electrons outside the nucleus and gamma rays are emitted by the excited nucleus Gamma rays are highly penetrating and highly energetic than the X-rays. Gamma rays have shorter wavelengths and the X-rays have larger wavelength. The difference between gamma rays and X-rays is as follows.
| Gamma rays | X-rays |
| 1) The gamma rays are emitted by the excited nucleus. | 1) X-rays are emitted by the electrons outside the nucleus. |
| 2) The gamma rays are due to the disintegration of electrons. | 2) The X-rays are due to the fast moving electron nucleus. |
| 3) Whenever there is energy changes in the nucleus of atom gamma rays are formed. | 3) Whenever there is energy changes in the level of atom X-rays are formed. |
| 4) The gamma rays have shorter wavelength. | 4)The X-rays have the larger wavelength. |
| 5) The gamma rays have the high penetration power. | 5) The X-rays have the low penetration power. |
| 6) The gamma rays have many application in radiation field. | 6) The X-rays have many application in medical field. |
| 7) The gamma rays equipment are of small size. | 7) The X-ray instruments are larger in size. |
| 8) The gamma rays have high energy. | 8) The X-rays have less energy. |
What is radiographic film processing?
When the film is processed, it is exposed to several different chemicals solutions for controlled periods of time.
Processing film basically involves the following five steps.
Development – The developing agent gives up electrons to convert the silver halide grains to metallic silver. Grains that have been exposed to the radiation develop more rapidly, but given enough time the developer will convert all the silver ions into silver metal. Proper temperature control is needed to convert exposed grains to pure silver while keeping unexposed grains as silver halide crystals.
Stopping the development – The stop bath simply stops the development process by diluting and washing the developer away with water.
Fixing – Unexposed silver halide crystals are removed by the fixing bath. The fixer dissolves only silver halide crystals, leaving the silver metal behind.
Washing – The film is washed with water to remove all the processing chemicals.
Drying – The film is dried for viewing.
What is radiographic film interpretation
Interpretation of radiograph is the analysis of the image formed on the film by radiation transmission pattern of the test specimen. The image is evaluated in terms of internal and external discontinuities of the specimen.