Volume 17 - Nondestructive Evaluation and Quality Control Part 10 pptx

[...]... (depleted) developer Testpiece-to-film distance too long If possible, decrease testpiece-to-film distance; if not, increase sourceto-film distance Source-to-film distance too short Increase source-to-film distance Focal spot (or large Use smaller source or increase source-to-film distance Density too low Contrast too high Contrast too low Poor definition -ray source) too Screens and film not in close contact... flaw size and severity Table 13 Reference radiographs in ASTM standards ASTM standard Subject of radiographs in standard E 155 Aluminum and magnesium castings E 186 Heavy-wall (5 0-1 15 mm, or 2-4 in.) steel castings E 192 Investment steel castings for aerospace applications E 242 Appearance of radiographic images as certain parameters are changed E 272 High-strength copper-base and nickel-copper alloy... The thickness needed depends on radiation quality; for example, 3 mm ( in.) of lead for 250-kV x-rays and 6 mm ( in.) of lead for 1-MeV x-rays or for Ir-192 or Co-60 -rays At 100 kV and lower, the lead that is frequently incorporated into the back of the cassette or film holder usually provides sufficient protection from back scatter Radiographic tables or stands can also be covered with lead to reduce... flaw size and severity Table 13 Reference radiographs in ASTM standards ASTM standard Subject of radiographs in standard E 155 Aluminum and magnesium castings E 186 Heavy-wall (5 0-1 15 mm, or 2-4 in.) steel castings E 192 Investment steel castings for aerospace applications E 242 Appearance of radiographic images as certain parameters are changed E 272 High-strength copper-base and nickel-copper alloy... sourceto-film distance Source-to-film distance too short Increase source-to-film distance Focal spot (or large Poor definition Increase development time or developer temperature Replace weak (depleted) developer Use smaller source or increase source-to-film distance -ray source) too Screens and film not in close contact Ensure intimate contact between screens and film Film graininess too coarse Use finer-grain... 200-kV x-rays could be light enough in weight for convenient handling, yet a mask for use with cobalt-60 radiation would be much thicker, heavier, and more cumbersome In any event, with either x-rays or -rays, the means for reducing the effects of secondary radiation must be selected with consideration of cost and convenience as well as the effectiveness Lead screens placed in contact with the front and. .. reinforcement as with the double-wall, double-image technique Radiation-source location with respect to the testpiece and the location of the penetrameter on the block or shim are the same as for a double-wall, double-image technique In any setup for single-wall, single-image radiography, the penetrameters can be placed only on the testpiece because the film is always on one side of the wall and the source on the... accurate evaluation of small variations in photographic density or for quantitative evaluation of radiographic and processing techniques A transmission densitometer is used with films, and a reflection densitometer is used with paper radiographs Radiographic Acceptance Standards Usually, a series of radiographs that exhibit various types and sizes of flaws should be selected for acceptance standards Parts... accurate evaluation of small variations in photographic density or for quantitative evaluation of radiographic and processing techniques A transmission densitometer is used with films, and a reflection densitometer is used with paper radiographs Radiographic Acceptance Standards Usually, a series of radiographs that exhibit various types and sizes of flaws should be selected for acceptance standards Parts... diffraction and porosity, and careful interpretation of the radiographs is needed to differentiate between them Mottling due to diffraction can be reduced, and sometimes eliminated, by raising x-ray tube voltage and by using lead screens Filters will usually aid in the control of diffraction Raising the tube voltage and filtration are often of positive value even though radiographic contrast and sensitivity . 2. 0-1 .6 13 3. 3-2 .5 8-1 0 0.3 0-0 .40 14 2. 0-1 .6 12 3. 1-2 .5 1 0-1 6 0.4 0-0 .60 13 2. 0-1 .3 11 3. 2-2 .0 1 6-2 5 0.6 0-1 .00 12 1. 6-1 .0 10 2. 5-1 .6 2 5-3 2 1.0 0-1 .25 11 1. 3-1 .0 9 2. 0-1 .6 3 2-4 0. 3 2-4 0 1.2 5-1 .60 10 1. 3-1 .0 8 2. 0-1 .6 4 0-5 0 1.6 0-2 .00 9 1. 3-1 .0 7 2. 0-1 .6 5 0-8 0 2.0 0-3 .15 8 1. 3-0 .8 6 2. 0-1 .3 8 0-2 00 3.1 5-8 .00 7 1. 0-0 .4 . . . . . . 8 0-1 50 3.1 5-6 .00 . . . . 5 1. 6-0 .8 150 -1 70 6.0 0-6 .70 . . . . . . 4 1. 1-0 .9 170 -1 80 6.7 0-7 .00 . . . . . . 3 1. 2-1 .1 18 0-1 90 7.0 0-7 .50 . . . . . . 2 1. 4-1 .3 19 0-2 00 7.5 0-8 .00 . .