Radiography in Modern Industry - Kodak

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The power supply for the x-ray tube filament consists of an insulating step-down transformer. Avariable-voltage transformer or a choke coil may serve for adjustment of the current supplied tothe filament.The high-voltage supply consists of a transformer, an autotransformer, and, quite frequently, arectifier.A transformer makes it possible to change the voltage of an alternating current. In the simplestform, it consists of two coils of insulated wire wound on an iron core. The coil connected to thesource of alternating current is called the primary winding, the other the secondary winding. Thevoltages in the two coils are directly proportional to the number of turns, assuming 100 percentefficiency. If, for example, the primary has 100 turns, and the secondary has 100,000, the voltagein the secondary is 1,000 times as high as that in the primary. At the same time, the current in thecoils is decreased in the same proportion as the voltage is increased. In the example given,therefore, the current in the secondary is only 1/1,000 that in the primary. A step-up transformer isused to supply the high voltage to the x-ray tube.An autotransformer is a special type of transformer in which the output voltage is easily variedover a limited range. In an x-ray generator, the autotransformer permits adjustment of the primaryvoltage applied to the step-up transformer and, hence, of the high voltage applied to the x-raytube.The type of voltage waveform supplied by a high-voltage transformer is shown in part A of thefigure 6 and consists of alternating pulses, first in one direction and then in the other. Someindustrial x-ray tubes are designed for the direct application of the high-voltage waveform of partA of the figure below, the x-ray tube then acting as its own rectifier. Usually, however, the highvoltage is supplied to a unit called a rectifier, which converts the pulses into the unidirectionalform illustrated in part B of the figure below. Another type of rectifier may convert the waveform tothat shown in part C of the figure below, but the general idea is the same in both cases--that is,unidirectional voltage is supplied to the x-ray tube. Sometimes a filter circuit is also provided that"smooths out" the voltage waves shown in parts Band C of the figure below, so that essentiallyconstant potential is applied to the x-ray tube, part D of the figure below. Many different highvoltagewaveforms are possible, depending on the design of the x-ray machine and itsinstallation. Figure 6 shows idealized waveforms difficult to achieve in practical high-voltageequipment. Departures from these terms may vary in different x-ray installations. Since x-rayoutput depends on the entire waveform, this accounts for the variation in radiographic resultsobtainable from two different x-ray machines operating at the same value of peak kilovoltage.Radiography in Modern Industry 12
Figure 6: Typical voltage waveforms of x-ray machines.Tubes with the anodes at the end of a long extension cylinder are known as "rod-anode" tubes.The anodes of these tubes can be thrust through small openings (See Figure 7, top) to facilitatecertain types of inspection. If the target is perpendicular to the electron stream in the tube, the x-radiation through 360 degrees can be utilized (See Figure 7, bottom), and an entirecircumferential weld can be radiographed in a single exposure.With tubes of this type, one special precaution is necessary. The long path of the electron streamdown the anode cylinder makes the focusing of the electrons on the target very susceptible tomagnetic influences. If the object being inspected is magnetized--for example, if it has undergonea magnetic inspection and has not been properly demagnetized--a large part of the electronstream can be wasted on other than the focal-spot area, and the resulting exposures will beerratic.The foregoing describes the operation of the most commonly used types of x-ray equipment.However, certain high-voltage generators operate on principles different from those discussed.Radiography in Modern Industry 13
Page 1 and 2: RadiographyinModernIndustry
Page 3 and 4: RadiographyinModernIndustryFOURTH E
Page 5 and 6: ContentsIntroduction...............
Page 7 and 8: Chapter 1: The Radiographic Process
Page 9 and 10: Intensifying ScreensX-ray and other
Page 11: makes it a very suitable material f
Page 15 and 16: Table I - Typical X-ray Machines an
Page 17 and 18: The wavelengths (or energies of rad
Page 19 and 20: Table III - Industrial Gamma-Ray So
Page 21 and 22: 1. The source of light should be sm
Page 23 and 24: B and H in the Figure 13 show the e
Page 25 and 26: Figure 14: Geometric construction f
Page 27 and 28: Figure 17: Pinhole pictures of the
Page 29 and 30: The kilovoltage applied to the x-ra
Page 31 and 32: Figure 21: Schematic diagram of som
Page 33 and 34: kind of material radiographed, the
Page 35 and 36: instance, the kilovoltage may be fi
Page 37 and 38: The technique need not be limited t
Page 39 and 40: Chapter 5: Radiographic ScreensWhen
Page 41 and 42: Contact between the film and the le
Page 43 and 44: Figure 29: The number of electrons
Page 45 and 46: lead foil screens ran be retained w
Page 47 and 48: Figure 33: The sharpness of the rad
Page 49 and 50: Figure 34: Low density (right) is a
Page 51 and 52: such as a wall or floor, on the fil
Page 53 and 54: from this source. Since scatter als
Page 55 and 56: A filter reduces excessive subject
Page 57 and 58: Definite rules as to filter thickne
Page 59 and 60: 0.010-inch front screen of value be
Page 61 and 62: Example: Suppose that with a given
Page 63 and 64:
If the milliamperage remains consta
Page 65 and 66:
espectively. In other words, a cons
Page 67 and 68:
Any given exposure chart applies to
Page 69 and 70:
Figure 46: Typical gamma-ray exposu
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where the slope of the characterist
Page 73 and 74:
Figure 49: Characteristic curves of
Page 75 and 76:
Figure 51: Characteristic curve of
Page 77 and 78:
Nomogram MethodsIn Figure 54, the s
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Figure 56: Transparent overlay posi
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Figure 58: Overlay positioned so as
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The problem of radiographing a part
Page 85 and 86:
Figure 62: System of lines drawn on
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Chapter 8: Radiographic Image Quali
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Film contrast refers to the slope (
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Hole Type PenetrametersThe common p
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of the same thickness as the specim
Page 95 and 96:
Chapter 9: Industrial X-ray FilmsMo
Page 97 and 98:
Figure 70 indicates the direction t
Page 99 and 100:
the lead letters on a radiation-abs
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Therefore, protection requirements
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5. Avoid pressure damage caused by
Page 105 and 106:
Paddles or plunger-type agitators a
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slow, and the development time reco
Page 109 and 110:
ubbles make their way to the surfac
Page 111 and 112:
When development is complete, the f
Page 113 and 114:
soften considerably with prolonged
Page 115 and 116:
Figure 77: The roller transport sys
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Rapid Access to Processed Radiograp
Page 119 and 120:
Figure 78: Film-feeding procedures
Page 121 and 122:
Chapter 11: Process ControlUsers of
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3. Age of the developer replenisher
Page 125 and 126:
Figure 80: Control chart below for
Page 127 and 128:
DiscussionDensitometric data and pr
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Figure 82: Plan of a manual x-ray p
Page 131 and 132:
Figure 83: A schematic diagram of a
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loading-bench activities are carrie
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KODAK Quinone-Thiosulfate Intensifi
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Methylene-Blue MethodTwo variations
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KODAK Hypo Test Solution HT-2Avoird
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In summary, use of the test papers
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narrow angle would be very thick, e
Page 145 and 146:
When radiation passes through a spe
Page 147 and 148:
Figure 89: Demonstration of the eff
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Figure 90: The amount of gamma radi
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The radiograph exposed in the right
Page 153 and 154:
To illustrate, let us assume that t
Page 155 and 156:
Figure 95: High-speed x-ray picture
Page 157 and 158:
Figure 97: Two methods of neutron r
Page 159 and 160:
Duplicating RadiographsSimultaneous
Page 161 and 162:
Sometimes, as when sets of referenc
Page 163 and 164:
PhotofluorographyIn photofluorograp
Page 165 and 166:
discontinuities or of segregation i
Page 167 and 168:
from the camera or by reaching down
Page 169 and 170:
Figure 106: Schematic diagram of th
Page 171 and 172:
valuable technique, for instance, i
Page 173 and 174:
The position of the spots is determ
Page 175 and 176:
Powder Diffraction File, Internatio
Page 177 and 178:
Processing TechniquesRadiographs on
Page 179 and 180:
Since this formula applies only to
Page 181 and 182:
such that it does not distort the i
Page 183 and 184:
Figure 113: A: Representation of a
Page 185 and 186:
Figure 115: Characteristic curve of
Page 187 and 188:
film fairly well. If high densities
Page 189 and 190:
Density = 1.5 Density = 2.5Film Rel
Page 191 and 192:
In most industrial radiography, the
Page 193 and 194:
e noted here. Although the average
Page 195 and 196:
Chapter 17: Film Graininess; Signal
Page 197 and 198:
The ratio of signal to noise has a
Page 199 and 200:
Chapter 18: The Photographic Latent
Page 201 and 202:
Thus, the change that makes an expo
Page 203 and 204:
Figure 130: Stages in the developme
Page 205 and 206:
electrons by successive Compton int
Page 207 and 208:
Development is essentially a chemic
Page 209 and 210:
Chapter 19: ProtectionOne of the mo
Page 211 and 212:
duct is brought into the x-ray room
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Radiography in Modern Industry - Kodak

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