In Radiography Testing the test-part is placed between the radiation source and film. The material density and thickness differences of the test-part will stop, or partially stop, some of the penetrating radiation through a process called scattering and/or absorption. The differences in absorption are then recorded on film(s) or through an electronic means. In industrial radiography there are several imaging methods available, techniques to display the final image, i.e. Film Radiography, Real Time Radiography (RTR), Computed Tomography (CT), Digital Radiography (DR), and Computed Radiography (CR).
There are two different radioactive sources available for industrial use; namely the X-ray and Gamma-ray. These radiation sources use higher energy level, i.e. shorter wavelength, version of the electromagnetic waves. Because of the radioactivity involved in Radiography Testing, it is paramount important to ensure that the Local Rules is strictly adhered during the operation.
Computed Tomography (CT) is one of the lab based Advanced NDT methods that TWI is offering to the industries. This X-ray inspection technique produces high-resolution 3D images of components which can be viewed from any 3D angle, sliced in any direction, measured and even animated in a virtual workspace. This feature allows detailed analysis of the internal structure of a wide range of components.
TWI Resources
TWI has acquired the following Digital Radiography equipment for Computed Tomography (CT) to cater for the industrial needs.
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X-Tek 75 keV System
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X-Tek 450 keV System
In CT the test-part is X-rayed from a range of angles over 360 degrees. Together with this installation, a manipulator designed with a 5-degree of freedom to ensure full coverage of test-part. Specially designed software uses the X-ray images to calculate the density at all points within the test volume to create a 3D model of the component. The model can be rotated and viewed from any desired position and angle. CT enables complex 3D analysis of the structure of components.
Benefits
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Technique is not limited by material density or type
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Can inspect assembled components
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Minimum surface preparation required
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Detects both surface and subsurface defects
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Provides a permanent record of the inspection
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Verify internal flaws on complex structures
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Isolate and inspect internal components
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Automatically detect and measure internal flaws
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Measure dimensions and angles within the sample without sectioning
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Sensitive to changes in thickness, corrosion, flaws and material density changes
Applications
TWI utilises this Computed Tomography to inspect complex structural components and various types’ of safety/ critical components such as small machine parts, valves of intricate design, glow plugs, gauges, sensors, turbine blades, etc.
Radiographic Testing is widely used in the;
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