Radiography in Modern Industry - Kodak

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IntroductionMany of the spectacular scientific and engineering achievements of the past few years can betraced to nondestructive testing methods, which--by determining internal soundness withoutdestroying product usefulness--assure the satisfactory performance for which the product wasintended.Radiography today is one of the most important, most versatile, of all the nondestructive testmethods used by modern industry. Employing highly penetrating x-rays, gamma rays, and otherforms of radiation that do not damage the part itself, radiography provides a permanent visiblefilm record of internal conditions, containing the basic information by which soundness can bedetermined. In the past decade alone, the evidence from millions of film records, or radiographs,has enabled industry to assure product reliability; has provided the informational means ofpreventing accidents and saving lives; and has been beneficial for the user.Since economic justification is a major criterion for any testing method, the value of radiographylies to some extent in its ability to make a profit for its user. This value is apparent in machiningoperations where only pieces known to be sound are permitted on the production lines. It isequally apparent in cost reductions when less expensive materials or fabricating methods can beemployed instead of costlier ones in which soundness is only an estimated quality. Theinformation gained from the use of radiography also assists the engineer in designing betterproducts and protects the company by maintaining a uniform, high level of quality in its products.In total, these advantages can help to provide customer satisfaction and promote themanufacturers reputation for excellence.Industrial radiography is tremendously versatile. Objects radiographed range in size from microminiatureelectronic parts to mammoth missile components; in product composition throughvirtually every known material; and in manufactured form over an enormously wide variety ofcastings, weldments, and assemblies. Radiographic examination has been applied to organic andinorganic materials, and to solids, liquids, and even gases. An industry's production ofradiographs may vary from the occasional examination of one or several pieces to theexamination of hundreds of specimens per hour. This wide range of applications has resulted inthe establishment of independent, professional x-ray laboratories as well as of radiographicdepartments within manufacturing plants themselves. The radiographic inspection performed byindustry is frequently monitored for quality by its customers -- other manufacturers orgovernmental agencies -- who use, for the basis of monitoring, applicable specifications or codes,mutually agreed to by contract, and provided by several technical societies or other regulatorygroups.To meet the growing and changing demands of industry, research and development in the field ofradiography are continually producing new sources of radiation such as neutron generators andradioactive isotopes; lighter, more powerful, more portable x-ray equipment as well asmultimillion-volt x-ray machines designed to produce highly penetrating radiation; new andimproved x-ray films and automatic film processors; and improved or specialized radiographictechniques. These factors, plus the activities of many dedicated people, extend radiography'susefulness to industry.It is not surprising then, that radiography, the first of the modern sophisticated methods of nondestructivetesting (dating back to 1895), has led hundreds of industries to put great confidence inthe information that it supplies. The list is growing year after year as industry's management,designers, engineers, production men, inspectors, and everyone concerned with sound practices,dependable products, high yields, and reasonable profits discover the value of radiography inmodern industry.
Chapter 1: The Radiographic ProcessNature of X-RaysX-rays are a form of electromagnetic radiation (EMR), as is light. Their distinguishing feature istheir extremely short wavelength--only about 1/10,000 that of light, or even less. Thischaracteristic is responsible for the ability of x-rays to penetrate materials that absorb or reflectordinary light.X-rays exhibit all the properties of light, but in such a different degree as to modify greatly theirpractical behavior. For example, light is refracted by glass and, consequently, is capable of beingfocused by a lens in such instruments as cameras, microscopes, telescopes, and spectacles. X-rays are also refracted, but to such a very slight degree that the most refined experiments arerequired to detect this phenomenon. Hence, it is impractical to focus x-rays. It would be possibleto illustrate the other similarities between x-rays and light but, for the most part, the effectsproduced are so different--particularly their penetration--that it is preferable to consider x-rays andgamma rays separately from other radiations. The figure below shows their location in theelectromagnetic spectrum.Figure 1: Portion of the electromagnetic spectrum. Wavelengths in angstrom units (1A =10 -8 cm = 3.937 x 10 -9 inch)Nature of Gamma RaysGamma rays are similar in their characteristics to x-rays and show the same similarities to, anddifferences from, visible light as do x-rays. They are distinguished from x-rays only by theirsource, rather than by their nature. Gamma rays are emitted from the disintegrating nuclei ofradioactive substances, and the quality (wavelength or penetration) and intensity of the radiationcannot be controlled by the user. Some gamma-ray-emitting radioactive isotopes, such asradium, occur naturally. Others, like cobalt 60, are artificially produced. In industrial radiography,the artificial radioactive isotopes are used almost exclusively as sources of gamma radiation.Making a RadiographA radiograph is a photographic record produced by the passage of x-rays or gamma rays throughan object onto a film. See the figure below. When film is exposed to x-rays, gamma rays, or light,an invisible change called a latent image is produced in the film emulsion. The areas so exposedbecome dark when the film is immersed in a developing solution, the degree of darkeningdepending on the amount of exposure. After development, the film is rinsed, preferably in aspecial bath, to stop development. The film is next put into a fixing bath, which dissolves theundarkened portions of the sensitive salt. It is then washed to remove the fixer and dried so that itmay be handled, interpreted, and filed. The developing, fixing, and washing of the exposed filmmay be done either manually or in automated processing equipment.
Page 1 and 2: RadiographyinModernIndustry
Page 3 and 4: RadiographyinModernIndustryFOURTH E
Page 5: ContentsIntroduction...............
Page 9 and 10: Intensifying ScreensX-ray and other
Page 11 and 12: makes it a very suitable material f
Page 13 and 14: Figure 6: Typical voltage waveforms
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
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Definite rules as to filter thickne
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0.010-inch front screen of value be
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Example: Suppose that with a given
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If the milliamperage remains consta
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espectively. In other words, a cons
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Any given exposure chart applies to
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Figure 46: Typical gamma-ray exposu
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where the slope of the characterist
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Figure 49: Characteristic curves of
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Figure 51: Characteristic curve of
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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
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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
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Chapter 9: Industrial X-ray FilmsMo
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Figure 70 indicates the direction t
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the lead letters on a radiation-abs
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Therefore, protection requirements
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5. Avoid pressure damage caused by
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Paddles or plunger-type agitators a
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slow, and the development time reco
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ubbles make their way to the surfac
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When development is complete, the f
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soften considerably with prolonged
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Figure 77: The roller transport sys
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Rapid Access to Processed Radiograp
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Figure 78: Film-feeding procedures
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Chapter 11: Process ControlUsers of
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3. Age of the developer replenisher
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Figure 80: Control chart below for
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DiscussionDensitometric data and pr
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Figure 82: Plan of a manual x-ray p
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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
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When radiation passes through a spe
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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
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To illustrate, let us assume that t
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Figure 95: High-speed x-ray picture
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Figure 97: Two methods of neutron r
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Duplicating RadiographsSimultaneous
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Sometimes, as when sets of referenc
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PhotofluorographyIn photofluorograp
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discontinuities or of segregation i
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from the camera or by reaching down
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Figure 106: Schematic diagram of th
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valuable technique, for instance, i
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The position of the spots is determ
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Powder Diffraction File, Internatio
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Processing TechniquesRadiographs on
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Since this formula applies only to
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such that it does not distort the i
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Figure 113: A: Representation of a
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Figure 115: Characteristic curve of
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film fairly well. If high densities
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Density = 1.5 Density = 2.5Film Rel
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In most industrial radiography, the
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e noted here. Although the average
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Chapter 17: Film Graininess; Signal
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The ratio of signal to noise has a
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Chapter 18: The Photographic Latent
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Thus, the change that makes an expo
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Figure 130: Stages in the developme
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electrons by successive Compton int
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Development is essentially a chemic
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Chapter 19: ProtectionOne of the mo
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duct is brought into the x-ray room
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Radiography in Modern Industry - Kodak

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