ASTM E242-95(2000)

Standard Reference Radiographs for Appearances of Radiographic Images as Certain Parameters Are Changed

SCOPE
1.1 This document describes the appearance of a radiographic image where fundamental components of image quality are changed, that is, variables such as whether a X-ray or gamma ray source was used, the characteristics of the radiographic film and intensifying screens, and the geometrical configuration of the object under investigation as well as its associated radiographic set-up.
1.2 These reference radiographs  consist of four composite illustrations  and show how such factors as radiation energy, specimen thickness, and film properties affect the radiographic image.  
1.3 The values stated in inch-pound units are to be regarded as the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Jun-2001
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.02 - Reference Radiological Images

Relations

• Replaced By: ASTM E242-01 - Standard Reference Radiographs for Appearances of Radiographic Images as Certain Parameters Are Changed
• Effective Date: 10-Jun-2001
• Referred By: ASTM E1032-19 - Standard Practice for Radiographic Examination of Weldments Using Industrial X-Ray Film
• Effective Date: 10-Jun-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 242 – 95 (Reapproved 2000) An American National Standard
Standard Reference Radiographs for
Appearances of Radiographic Images as Certain Parameters
Are Changed
This standard is issued under the fixed designation E 242; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 This document describes the appearance of a radio- 4.1 A key consideration with any radiographic system is its
graphic image where fundamental components of image qual- capability to resolve detail (that is, sensitivity). The degree of
ity are changed, that is, variables such as whether a X-ray or obtainable sensitivity with a given system is dependent upon
gamma ray source was used, the characteristics of the radio- several radiographic parameters such as source energy level,
graphic film and intensifying screens, and the geometrical film type, type and thickness of intensifying screens, and
configuration of the object under investigation as well as its material thickness radiographed. These reference radiographs
associated radiographic set-up. permit the user to estimate the degree of sensitivity change that
1.2 These reference radiographs consist of four composite may be obtained when these parameters are varied from a
illustrations and show how such factors as radiation energy, specific technique. This standard may also be used in conjunc-
specimen thickness, and film properties affect the radiographic tion with Test Method E 746 to provide a basis for developing
image. data for evaluation of a user’s specific system. This data may
1.3 The values stated in inch-pound units are to be regarded assist a user in determining appropriate parameters for obtain-
as the standard. ing desired degrees of radiographic system sensitivity.
1.4 This standard does not purport to address all of the
5. Factors Affecting Radiographic Appearance
safety concerns, if any, associated with its use. It is the
5.1 The final interpretation of the radiograph is greatly
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- affected by the appearance of a discontinuity. A poor technique
can minimize the radiographic appearance of a discontinuity
bility of regulatory limitations prior to use.
and conversely the optimum technique can emphasize this
2. Referenced Documents
appearance. The appearance of a radiographic image is affected
2.1 ASTM Standards: mainly by:
E 94 Guide for Radiographic Testing 5.1.1 X-ray or gamma ray energy.
E 746 Test Method for Determining Relative Image Quality 5.1.2 Section thickness,
Response of Industrial Radiographic Film 5.1.3 Unsharpness, and
E 1316 Terminology for Nondestructive Examinations 5.1.4 Film and screen combinations.
2.2 ASTM Adjuncts: 5.2 The equation that considers most of the above factors is:
Reference Radiographs for Appearances of Radiographic
Dx 5 @c~d 2 d !/Gμ#~kx 1 1! (1)
1 2
Images as Certain Parameters Are Changed
where:
3. Terminology
Dx = thickness of discontinuity,
c = constant,
3.1 Definitions: For definitions of terms used in this docu-
d −d = minimum density change perceptible by eye,
ment, see Terminology E 1316, Section D. 1 2
G = film gradient,
μ = linear absorption coefficient (effective),
k = scattering coefficient, and
x = section thickness.
These reference radiographs are under the jurisdiction of ASTM Committee As the above equation shows, the minimum thickness of
E-7 on Nondestructive Testing and are the direct responsibility of Subcommittee
detectable discontinuity (Dx) is:
E 07.02on Reference Radiographs.
5.2.1 A function of X-ray energy,
Current edition approved Dec. 10, 1995. Published February 1996. Originally
5.2.2 A function of section thickness, and
published as E 242 – 64 T. Last previous edition E 242 – 91.
For ASME Boiler and Pressure Code applications see related Reference
5.2.3 An inverse function of film gradient.
Radiographs SE-242 in the Code.
5.3 Although not clearly indicated by the above relation, the
Available from ASTM Headquarters. Order PCN 17-502420-22.
Annual Book of ASTM Standards, Vol 03.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 242
size of detectable discontinuity is also a function of unsharp- the greater penetration of the radiation; that is, because of
ness, see Guide E 94. decreasing subject contrast. The reference radiographs permit a
comparison of the radiographic appearance of the weld, at
6. Radiographic Illustrations
particular thickness over a range of X-ray or gamma ray
6.1 A series of 36 radiographs, each on 10 by 12-in. (254 by
energies.
305-mm) film, were taken of a 12 by 12 in. welded steel plate
7.2 Another condition that affects radiographic appearance
which contained discontinuities in the weld. These were taken
is the variation of thickness for a given X-ray or gamma ray
to illustrate the differences in appearance of the radiographic
energy. As the thickness of inspected material is increased, a
image when techniques for taking radiographs are varied by
discontinuity becomes less distinct in the radiographic image.
changing the factors listed in Section 5. A 2 by 2 in. (51 by 51
This is due to two predominant factors:
mm) area, which includes the identical image of the disconti-
7.2.1 The X-ray or gamma ray beam divergence which
nuities in the weld, was selected and cut out from each 10 by
produces unsharpness on the film when traversing a large
12 in. radiograph and arranged so as to make four composite
thickness.
illustrations identified as Fig. 1 through Fig. 4. These compos-
7.2.2 Scattered radiation within the material, which reduces
ite illustrations are an abridged version of the original 36
the radiographic contrast.
radiographs and serve as the reference radiographs for this
document. Following are brief descriptions of these figures.
7.2.3 The above processes are a function of material thick-
6.1.1 Figure 1—Composite Illustration A consists of cut
ness and X-ray or gamma ray energy. This effect is illustrated
outs from the 10 radiographs taken of the 1-in. (25-mm) thic
...