Detail of GB/T 26642-2022

Introduction of GB/T 26642-2022

GB/T 26642-2022 Non-destructive testing—Industrial computed radiography with storage phosphor imaging plates—General principles for testing of metallic materials using X-rays and gamma rays 1 Scope This document specifies fundamental techniques of computed radiography with the aim of enabling satisfactory and repeatable results to be obtained economically. The techniques are based on the fundamental theory of the subject and tests measurements. This document specifies the general rules for industrial computed X-rays and gamma radiography for detection purposes, using storage phosphor imaging plates (IP). It is based on the general principles for radiographic examination of metallic materials on the basis of films, as specified in ISO 5579. The basic set-up of radiation source, detector and the corresponding geometry are intended to be applied in accordance with ISO 5579 and corresponding product standards such as ISO 17636 for welding and EN 12681 for foundry. This document does not lay down acceptance criteria of the imperfections. Computed radiography (CR) systems provide a digital grey value image which can be viewed and evaluated on basis of a computer only. This practice describes the recommended principles for detector selection and radiographic practice. Computer, software, monitor, printer and viewing conditions are important but not the main focus of this document. It specifies the minimum requirements of computed radiography and digital radiographs to permit a sensitivity of imperfection detection equivalent to film radiography and as specified in ISO 5579. Some application standards, e.g. EN 16407, require different and less stringent practice conditions. 2 Normative references The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 21355-2022 Non-destructive testing - Industrial computed radiography with storage phosphor imaging plates - Classification of systems (ISO 16371-1 : 2011, IDT) ISO 5579 Non-destructive testing - Radiographic testing of metallic materials using film and X- or gamma rays - Basic rules Note: GB/T 19943-2005 Non-destructive test--Radiographic examination of metallic materials by X-and gamma-rays - Basic rules (ISO 5579:1998, IDT) ISO 5580 Non-destructive testing - Industrial radiographic illuminators - Minimum requirements Note: GB/T 19802-2005 Non-destructive testing--Industrial radiographic illuminators - Minimum requirements (ISO 5580 : 1985, IDT) ISO 9712 Non-destructive testing - Qualification and certification of NDT personnel Note: GB/T 9445-2015 Non-destructive testing - Qualification and certification of NDT personnel (ISO 9712 : 2012, IDT) ISO 16371-1 Non-destructive testing - Industrial computed radiography with storage phosphor imaging plates - Part 1 : Classification of systems ISO 19232-1 Non-destructive testing - Image quality of radiographs - Part 1 : Determination of the image quality value using wire-type image quality indicators Note: GB/T 23901.1-2019 Non-destructive testing - Image quality of radiographs - Part 1:Determination of the image quality value using wire-type image quality indicators (ISO 19232-1:2013, IDT) ISO 19232-2 Non-destructive testing - Image quality of radiographs - Part 2 : Determination of the image quality value using step/hole-type image quality indicators Note: GB/T 23901.2-2019 Non-destructive testing - Image quality of radiographs - Part 2:Determination of the image quality value using step/hole-type image quality indicators (ISO 19232-2 : 2013, IDT) ISO 19232-3 Non-destructive testing - Image quality of radiographs - Part 3 : Image quality classes Note: GB/T 23901.3-2019 Non-destructive testing - Image quality of radiographs - Part 3:Image quality classes (ISO 19232-3 : 2013, IDT) ISO 19232-5 Non-destructive testing - Image quality of radiographs - Part 5 : Determination of the image unsharpness and basic spatial resolution value using duplex wire-type image quality indicators Note: GB/T 23901.5-2019 Non-destructive testing - Image quality of radiographs - Part 5:Determination of the image quality unsharpness and basic spatial resolution value using duplex wire-type image quality indicators (ISO 19232-5 : 2018, IDT) EN 12543 (all parts) Non-destructive testing - Characteristics of focal spots in industrial X-ray systems for use in non-destructive testing EN 12679 Non-destructive testing - Radiographic testing - Determination of the size of industrial radiographic gamma sources 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: ——ISO Online browsing platform: https://www.iso.org/obp; ——IEC Electropedia: available at: http://www.electropedia.org/. 3.1 computed radiography system CR system complete system comprising a storage phosphor imaging plate (IP) and a corresponding read-out unit (scanner or reader) and system software, which converts the information from the IP into a digital image 3.2 storage phosphor imaging plate imaging plate; IP photostimulable luminescent material capable of storing a latent radiographic image of a material being examined and upon stimulation by a source of red light of appropriate wavelength, generates luminescence proportional to radiation absorbed Note: When performing computed radiography (3.1), an IP is used in lieu of a film. When establishing techniques related to source size or focal geometries, the IP is referred to as a detector, i.e. source-to-detector distance (SDD). 3.3 structure noise of imaging plate structure noise of IP fixed pattern noise measured due to IP structure which is inherent from inhomogeneities in the sensitive layer (graininess) and surface of a storage phosphor imaging plate (3.2) Note 1: After scanning of the exposed imaging plate, the inhomogeneities appear as overlaid fixed pattern noise in the digital image. Note 2: This noise limits the maximum achievable image quality of digital CR images and can be compared with the graininess in film images.

Contents of GB/T 26642-2022

Foreword I 1 Scope 2 Normative references 3 Terms and definitions 4 Symbols and abbreviated terms 5 Personnel qualification 6 Classification of computed radiographic techniques and compensation principles 7 General 8 Recommended techniques for making computed radiographs 9 Test report Annex A (Nominative) Determination of basic spatial resolution, SRbdetector Annex B (Nominative) Determination of normalized SNRN from SNRmeasured Annex C (Nominative) Determination of minimum grey value Bibliography