Understanding NRT- Reading 1- 2 of 2- Radiogaphic Testing A
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
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Film viewers should be clean and in good working condition. There are four<br />
groups <strong>of</strong> film viewers. These include: strip viewers, area viewers, spot<br />
viewers, and a combination <strong>of</strong> spot and area viewers. Film viewers should<br />
provide a source <strong>of</strong> defused, adjustable, and relativity cool light as heat from<br />
viewers can cause distortion <strong>of</strong> the radiograph. A film having a measured<br />
density <strong>of</strong> 2.0 will allow only 1.0 percent <strong>of</strong> the incident light to pass. A film<br />
containing a density <strong>of</strong> 4.0 will allow only 0.01 percent <strong>of</strong> the incident light to<br />
pass. With such low levels <strong>of</strong> light passing through the radiograph the delivery<br />
<strong>of</strong> a good light source is important.<br />
The radiographic process should be performed in accordance with a written<br />
procedure or code, or as required by contractual documents. The required<br />
documents should be available in the viewing area and referenced as<br />
necessary when evaluating components. Radiographic film quality and<br />
acceptability, as required by the procedure, should first be determined.<br />
Charlie Chong/ Fion Zhang
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