Non-destructive testing with radiographic and gammagraphic methods
C.M.C. Sud, a point of reference at national and international level in the non-destructive testing sector for over 45 years, carries out non-destructive testing with the radiographic and gammagraphic method, using a beam of ionizing radiation directed against the piece under examination. The choice between the two methods depends on the specific needs of the application and the material to be inspected.
Radiographic method
The radiographic method involves the use of X-rays or gamma rays to produce images of the materials being inspected. An x-ray machine (X-ray tube or linear accelerator) emits radiation that passes through the material and creates an image on a sensitive detector. Dense areas absorb radiation more, producing darker areas in the x-ray image, highlighting material gaps (defects such as cracks or cavities) or inclusions of foreign material. Used in the manufacturing industry to inspect welds, castings and metal components, it also finds applications in civil engineering to analyze building and bridge structures.
The gammagraphic method is a specific form of radiography that uses radioactive sources, such as Cobalt-60 or Iridium-192. These sources do not require electrical power, and are much smaller in size than X-ray tubes, making this technique ideal for construction site inspections. Furthermore, the higher energy of the radiation used allows to check greater thicknesses than X-rays. Widely used in the Oil & Gas sector to inspect pipes and pressure vessels, this method allows you to check complex structures that are difficult to access.
The C.M.C. Sud has equipment to perform gammagraphy using Cobalt-60. The use of this source allows to carry out checks on high thicknesses (up to 200 mm of steel) even in difficult environmental situations. In the context of non-destructive testing (NDT), Cobalt-60 (Co-60) has proven to be a valuable source for detecting and evaluating imperfections within materials and structures without damaging them. Cobalt-60 is a radioactive source that emits high-energy gamma rays, making it ideal for industrial radiography. This technique is used to identify defects such as cracks, inclusions and porosity within metallic and non-metallic materials.
The advantages of radiography in NDT
1. Penetration Depth
Radiographs use X-rays or gamma rays that effectively penetrate materials, allowing the detection of defects within thick or dense components.
2. Simplicity of interpretation
Radiographs directly produce images of the internal structure of materials, allowing a direct evaluation that can be simpler and more accurate than instrumental methods.
3. Versatility
X-rays and gamma rays can pass through various materials, including metals, plastics and ceramics, making x-rays suitable for a wide range of industrial applications.
4. Quick Exposure
In cases where rapid inspection is required, the relatively short exposure times of radiographs can be advantageous, allowing rapid results to be obtained.
The advantages of gammagraphies in NDT
1. Superior Penetration Depth
Radioactive sources used in gammagraphy, such as Cobalt-60, emit high-energy gamma rays that have greater penetrating power than X-rays.
2. Portability
Radioactive sources are relatively portable, allowing flexible inspection in different positions and angles, both in the field and in the laboratory.
3. Structural Safety
Gammagraphy is invaluable in the inspection of complex and inaccessible structures, such as underground pipes, where they can be used to carry out checks even in confined spaces.
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