Particulate Radiation:
There are three types of Particulate Radiation and they are of little concern to the average radiographer.
Particulate Radiation is different from X and Gamma Rays they have mass and do not travel at the speed of light.
However, Particulate Radiation will penetrate matter, will case ionization and cannot be detected by human senses.
Alpha Radiation as discussed in Lesson 4 has a positive charge and is slow and heavy.
Alpha Particles ionize atoms by removing electrons as they pass but they do not penetrate deeply.
Beta Particles (High Speed Electrons) have a negative charge and because they are lightweight, they are not as ionizing alpha particles.
Neutron Radiation has peculiar penetrating qualities. It penetrates many heavy elements with ease and is absorbed readily by many lighter elements, particularly Hydrogen.
Tag: RT
What Is Radiation:
X and Gamma Rays are a family of waves that are called electromagnetic waves. X-rays and gamma rays differ only in their source of origin. X-rays are produced by an x-ray generator and gamma radiation is the product of radioactive atoms. They are both part of the electromagnetic spectrum. They are waveform, as are light rays, microwaves, and radio waves. X-rays and gamma rays cannot been seen, felt, or heard. They possess no charge and no mass and, therefore, are not influenced by electrical and magnetic fields and will generally travel in straight lines. However, they can be diffracted (bent) in a manner similar to light.
General Principal Of Radiography:
1. The energy of the radiation affects its penetrating power. Higher energy radiation can penetrate thicker and more dense materials.
2. The radiation energy and/or exposure time must be controlled to properly image the region of interest.
Properties of X Ray & Gamma Rays:
Each photon contains a certain amount (or bundle) of energy, and all electromagnetic radiation consists of these photons. The only difference between the various types of electromagnetic radiation is the amount of energy found in the photons. Due to their short wavelength they have more energy to pass through matter than do the other forms of energy in the electromagnetic spectrum. As they pass through matter, they are scattered and absorbed and the degree of penetration depends on the kind of matter and the energy of the rays.
What is Radiation :
X and Gamma Rays are a family of waves that are called electromagnetic waves. X-rays and gamma rays differ only in their source of origin. X-rays are produced by an x-ray generator and gamma radiation is the product of radioactive atoms. They are both part of the electromagnetic spectrum. They are wave forms, as are light rays, microwaves, and radio waves. X-rays and gamma rays cannot been seen, felt, or heard. They possess no charge and no mass and, therefore, are not influenced by electrical and magnetic fields and will generally travel in straight lines. However, they can be diffracted (bent) in a manner similar to light.
The film darkness (density) will vary with the amount of radiation reaching the film through the test object.
The part is placed between the radiation source and a piece of film. The part will stop some of the radiation. Thicker and more dense area will stop more of the radiation.
Limitation of RT:
- Impracticable to use on specimens of complex geometry.
- Accessibility from both side required.
- Laminar type of discontinuity are often undetected by RT.
- Safety consideration imposed by X and Gamma Rays must be considered.
- It is relatively expensive & time consuming mean for NDT.
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.
post emulsifiable liquid penetration testing: It is divided in to two category:
- Method B: Post-Emulsifiable, Lipophilic
- Method D: Post-Emulsifiable, Hydrophilic
Water-Washable, is the most economical method & it has not replaceable for rough casting surface, threaded & key surfaces.
- Water-washable or self-emulsifiable penetrants contain an emulsifier as an integral part of the formulation.
- The excess penetrant is removed from the object surface with a simple water rinse.
- Penetrant materials have the property of forming relatively viscous gels upon contact with water, which results in the formation of gel-like plugs in surface openings.
- While they are completely soluble in water, given enough contact time, the plugs offer a brief period of protection against rapid wash removal. Thus, water-washable penetrant systems provide ease of use and a high level of sensitivity.
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