ASTM E242-15(R2020) pdf free download

ASTM E242-15(R2020) pdf free download.Standard Reference Radiographs for Appearances of Radiographic Images as Certain Parameters are Changed
1. Scope
1.1 This document describes the appearance of a radio- graphic image where fundamental components of image qual- ity are changed, that is, variables such as whether an X-ray or gamma ray source was used, the characteristics of the radio- graphic film (gradient, granularity, and developing conditions) and intensifying screens, and specimen thickness (the geo- metrical configuration ofthe radiographic set-up and focal spot size both affect image quality but are not considered in the reference radiographs). 1.2 The X-ray film systems used in obtaining the illustrative data were as follows: Very Fine Grain (comparable to class I of Test Method E1815) and Fine Grain (comparable to class II of Test Method E1815). 1.3 These reference radiographs 2 consist of four composite illustrations 3 and show how such factors as radiation energy, specimen thickness, and film properties affect the radiographic image. The reference radiograph films are an adjunct to this document and must be purchased separately from ASTM if needed. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.6 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Significance and Use
4.1 A key consideration with any radiographic system is its contrast resolution and spatial resolution capability (that is, sensitivity). The degree of obtainable sensitivity with a given system is dependent upon several radiographic parameters such as source energy level, film system class, type and thickness of intensifying screens, and material thickness radiographed. These reference radiographs permit the user to estimate the degree of sensitivity change that may be obtained when these parameters are varied from a specific technique. This standard may also be used in conjunction with Test Method E1815 or with Practice E746 or Test Method E1735 to provide a basis for developing data for evaluation of a user’s specific system. This data may assist a user in determining appropriate parameters for obtaining desired degrees of radiographic system sensitiv- ity.
6. Radiographic Illustrations
6.1 A series of 36 radiographs, each on 10-in. by 12-in. [254-mm by 305-mm] film, were taken of a 12-in. by 12-in. [305-mm by 305-mm] welded steel plate which contained discontinuities in the weld. These were taken to illustrate the differences in appearance of the radiographic image when techniques for taking radiographs are varied by changing the factors listed in Section 5. Technique data for each radiograph is in Table 1. A 2-in. by 2-in. [51-mm by 51-mm] area, which includes the identical image of the discontinuities in the weld, was selected and cut out from each 10-in. by 12-in. [254-mm by 305-mm] radiograph and arranged so as to make four composite illustrations identified as Figures 1 through 4. These composite illustrations are an abridged version of the original 36 radiographs and serve as the reference radiographs for this document. Following are brief descriptions of these figures. 6.1.1 Figure 1—Composite Illustration A consists of cut outs from the 10 radiographs taken of the 1-in. [25-mm] thick welded steel plate. 6.1.2 Figure 2—Composite Illustration B consists of cut outs from the 10 radiographs taken of the welded steel plate, built up to 2 in. [51 mm] in thickness. 6.1.3 Figure 3—Composite Illustration C consists of cut outs from the 10 radiographs taken of the welded steel plate, built up to 4 in. [102 mm] in thickness. 6.1.4 Figure 4—Composite Illustration D consists of cut outs from the 6 radiographs taken of the welded steel plate, built up to 6 in. [152 mm] in thickness. 6.2 The radiographic appearance of discontinuities in 1, 2, 4, and 6-in. [25-mm, 51-mm, 102-mm, and 152-mm] thick steel is shown in the series of composite radiographs. (These are full-scale reproductions of the same selected area from all the reference radiographs.) All composite sets of radiographs show the change in radiographic appearance in the specified thickness of steel plate as the parameters of X-ray or gamma ray energy and film systems or both are changed.