1.1 The reference radiographs provided in the adjunct to this standard illustrate various types and degrees of discontinuities occurring in thin-wall steel investment castings. 2 Use of this standard for the specification or grading of castings requires procurement of the adjunct reference radiographs which illustrate the discontinuity types and severity levels. They are intended to provide the following: 1.1.1 A guide enabling recognition of thin-wall steel casting discontinuities and their differentiation both as to type and degree through radiographic examination. 1.1.2 Example radiographic illustrations of discontinuities and a nomenclature for reference in acceptance standards, specifications and drawings. 1.2 Two illustration categories are covered as follows: 1.2.1 Graded- Six common discontinuity types each illustrated in eight degrees of progressively increasing severity. 1.2.2 Ungraded- Twelve single illustrations of additional discontinuity types and of patterns and imperfections not generally regarded as discontinuities. 1.3 The reference radiographs were developed for casting sections up to 1 in. (25.4 mm) in thickness. 1.4 This document may be used where there is no other applicable document existing or for other material thicknesses for which it is found to be applicable and for which agreement has been reached between the purchaser and manufacturer. Note 1 - The set of reference radiographs, produced with X-rays in the range from 130 to 250 kVp, consist of 16 plates (81/2 by 11 in. (216 by 279 mm)) in a 93/4 by 111/2-in. (248 by 292-mm) ring binder. 1.5 These film reference radiographs are not intended to illustrate the types and degrees of discontinuities found in aerospace investment castings when performing digital X-ray imaging. When performing digital X-ray imaging of these castings, refer to Digital Reference Image Standard E2660 . 1.6 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.7 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.