Monthly Archives for April 2018

Radiographic Examination – Exposure

The exposure of the photographic film by radiation passing through the workpiece is determined by the intensity of the radiation multiplied by the time of the exposure. The optical density of the developed negative increases with increasing exposure. ASME Code, … Continue reading

29. April 2018 by Jack
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Radiographic Examination – Photographic Film

The radiation which passes through the workpiece is recorded by photographic film. The radiographs are usually interpreted visually with the aid of a high intensity light source (light box), but optical densitometers or image analyzers are occasionally used. Two primary … Continue reading

29. April 2018 by Jack
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Radiographic Examination – Radiation Sources

Both x-rays and gamma rays can be used as the incident radiation. Energy and intensity are the most important characteristics of the incident radiation. The energy of the incident radiation determines its ability to penetrate the workpiece. Higher energy radiation … Continue reading

29. April 2018 by Jack
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Radiographic Examination – Physical Principles

X-rays and gamma rays penetrate steel, but the intensity of the incident radiation will be attenuated as it passes through the material. The degree of attenuation depends on the thickness and density of the material. Flaws can have the effect … Continue reading

29. April 2018 by Jack
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Radiographic Examination (RT)

RT is very useful for detecting both surface and internal flaws, and it is the primary NDE procedure required by the ASME Code to verify the quality of welds during construction. However, the associated radiation hazard makes it difficult to … Continue reading

29. April 2018 by Jack
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Shear Wave UT – Applications and Limitations

UT is a very efficient NDE method. A large amount of data for evaluating the integrity and reliability of a vessel can be obtained in a relatively short period of time, without requiring extensive preparation of the vessel or interfering … Continue reading

29. April 2018 by Jack
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Shear Wave UT – UT Imaging

UT imaging can be used to obtain two- and three-dimensional pictures of cracks, or other types of flaws, in a pressure vessel component from an automated ultrasonic examination. An ultrasonic transducer (either longitudinal or shear wave) is moved over the … Continue reading

29. April 2018 by Jack
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Shear Wave UT – Time Based Sizing

Time based sizing generally provides greater accuracy for determining depth, especially when the crack is relatively small with respect to the diameter of the transducer. Therefore, time based sizing should be used whenever a fitness-for-service analysis is made to evaluate … Continue reading

29. April 2018 by Jack
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Shear Wave UT – Amplitude Based Sizing

Figure 700-20 illustrates how the depth of a crack is determined using amplitude based sizing techniques. The crack was detected by shear wave UT as shown in Figure 700-19. The occurrence of a relatively high amplitude peak in the oscilloscope … Continue reading

28. April 2018 by Jack
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Shear Wave UT – Crack Sizing

The ability to determine the depth of a crack through the thickness of a vessel shell is a very important attribute of shear wave UT. However, the accuracy of the depth measurements made with UT can vary considerably, depending on … Continue reading

28. April 2018 by Jack
Categories: In-Service Inspection | Tags: | Leave a comment

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