EN ISO 17636-2:2022
(Main)Non-destructive testing of welds - Radiographic testing - Part 2: X- and gamma-ray techniques with digital detectors (ISO 17636-2:2022, Corrected version 2023-02)
Non-destructive testing of welds - Radiographic testing - Part 2: X- and gamma-ray techniques with digital detectors (ISO 17636-2:2022, Corrected version 2023-02)
This document specifies techniques of digital radiography with the object of enabling satisfactory and repeatable results. The techniques are based on generally recognized practice and fundamental theory of the subject.
This document applies to the digital radiographic testing of fusion welded joints in metallic materials. It applies to the joints of plates and pipes. Besides its conventional meaning, “pipe”, as used in this document, covers other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels.
This document specifies the requirements for digital radiographic X- and gamma-ray testing by either computed radiography (CR) or radiography with digital detector arrays (DDAs) of the welded joints of metallic plates and tubes for the detection of imperfections. It includes manual and automated inspection with DDAs.
Digital detectors provide a digital grey value image which can be viewed and evaluated using a computer (Annex E). This document specifies the recommended procedure for detector selection and radiographic practice. Selection of computer, software, monitor, printer and viewing conditions are important, but are not the main focus of this document. The procedure specified in this document provides the minimum requirements for radiographic practice which permits exposure and acquisition of digital radiographs with equivalent sensitivity for the detection of imperfections as film radiography (specified in ISO 17636-1).
This document does not specify acceptance levels for any of the indications found on the digital radiographs. ISO 10675 provides information on acceptance levels for weld inspection.
If contracting parties apply lower test criteria, it is possible that the quality achieved will be significantly lower than when this document is strictly applied.
Zerstörungsfreie Prüfung von Schweißverbindungen - Durchstrahlungsprüfung - Teil 2: Röntgen- und Gammastrahlungstechniken mit digitalen Detektoren (ISO 17636-2:2022, korrigierte Fassung 2023-02)
Dieses Dokument legt Techniken der digitalen Durchstrahlungsprüfung mit dem Ziel fest, zufriedenstellende und wiederholbare Ergebnisse zu erreichen. Die Techniken beruhen auf allgemein anerkannten Vorgehensweisen und den grundlegenden Theorien zum Thema.
Dieses Dokument ist anwendbar für die digitale Durchstrahlungsprüfung von Schmelzschweißverbindungen in metallischen Werkstoffen. Es ist anwendbar für Schweißverbindungen von Platten und Rohren. Neben der konventionellen Bedeutung werden in diesem Dokument unter der Benennung „Rohr“ auch andere zylindrische Körper wie Druckleitungen, Kesseltrommeln und Druckbehälter verstanden.
Dieses Dokument legt die Anforderungen an die digitale Durchstrahlungsprüfung von Schweißverbindungen an Metallplatten und -rohren mit Röntgen- und Gammastrahlen unter Anwendung entweder der Computer-Radiographie (CR) oder der Radiographie mit digitalen Matrixdetektoren (DDA, en: Digital Detector Arrays) fest, die dem Nachweis von Unregelmäßigkeiten dient. Es umfasst die manuelle und automatische Prüfung mittels DDA.
Digitale Detektoren liefern ein Bild mit digitalen Grauwerten, das mit einem Computer betrachtet und ausgewertet werden kann (Anhang E). Dieses Dokument legt die empfohlenen Verfahren für die Auswahl des Detektors und der Durchstrahlungstechnik fest. Die Auswahl von Computer, Software, Monitor, Drucker und Betrachtungsbedingungen ist von Bedeutung, bildet jedoch nicht den Schwerpunkt dieses Dokuments. Das in diesem Dokument festgelegte Verfahren enthält die Mindestanforderungen an das Durchstrahlungsverfahren zur Gewinnung digitaler Durchstrahlungsaufnahmen mit einer Empfindlichkeit für den Nachweis von Unregelmäßigkeiten, die der Radiographie mit Filmen (festgelegt in ISO 17636 1) gleichwertig ist.
Dieses Dokument legt keine Zulässigkeitsgrenzen für Anzeigen in den digitalen Durchstrahlungsaufnahmen fest. ISO 10675 enthält Informationen über Zulässigkeitsgrenzen bei der Prüfung von Schweißnähten (Schweißverbindungen).
Wenn die Vertragspartner niedrigere Prüfkriterien verwenden, ist es möglich, dass die erreichte Güte deutlich niedriger ist als bei strikter Anwendung von diesem Dokument.
Essais non destructifs des assemblages soudés - Contrôle par radiographie - Partie 2: Techniques par rayons X ou gamma à l'aide de détecteurs numériques (ISO 17636-2:2022, Version corrigée 2023-02)
Le présent document spécifie les techniques de radiographie numérique permettant d'obtenir des résultats satisfaisants et reproductibles. Les techniques reposent sur une pratique généralement reconnue et sur la théorie fondamentale en la matière.
Le présent document s'applique au contrôle par radiographie numérique des assemblages soudés par fusion de matériaux métalliques. Il s'applique aux assemblages de plaques et de tubes. Outre sa signification conventionnelle, le terme « tube », tel qu'il est utilisé dans le présent document, couvre d'autres corps cylindriques, tels que tuyaux, conduites forcées, réservoirs de chaudières et appareils à pression.
Le présent document spécifie les exigences relatives au contrôle par radiographie numérique à rayons X et gamma des assemblages soudés de tubes métalliques pour la détection des imperfections, soit par radiographie numérique (CR), soit par radiographie avec des panneaux de détecteurs numériques (DDA). Il comprend un contrôle manuel et automatisé avec des DDA.
Les détecteurs numériques produisent une image numérique en valeurs de gris qui ne peut être visualisée et évaluée qu'à l'aide d'un ordinateur (Annexe E). Le présent document spécifie le mode opératoire recommandé pour le choix des détecteurs et la pratique radiographique. Le choix de l'ordinateur, du logiciel, de l'écran, de l'imprimante et des conditions d'observation est important, mais ne constitue pas le centre d'intérêt du présent document. Le mode opératoire spécifié dans le présent document fournit les exigences minimales pour la pratique radiographique permettant l'exposition et l'acquisition des radiogrammes numériques avec une sensibilité de détection des imperfections équivalente à celle de la radiographie à l'aide de film (spécifiée dans l'ISO 17636‑1).
Le présent document ne spécifie pas les niveaux d'acceptation des indications trouvées sur les radiogrammes numériques. L'ISO 10675 fournit des informations sur les niveaux d'acceptation pour le contrôle des soudures.
Si les parties contractantes appliquent des critères d'essai moins rigoureux, il se peut que la qualité obtenue soit nettement inférieure à celle atteinte par l'application stricte du présent document.
Neporušitveno preskušanje zvarnih spojev - Radiografsko preskušanje - 2. del: Tehnike z rentgenskimi in gama žarki z uporabo digitalnih detektorjev (ISO 17636-2:2022)
Ta dokument določa tehnike digitalne radiografije z namenom omogočanja zadovoljivih in ponovljivih rezultatov. Tehnike so osnovane na splošno priznani praksi in temeljnem poznavanju subjekta.
Ta dokument se uporablja za digitalno radiografsko preskušanje talilno zvarjenih spojev v kovinskih materialih. Uporablja se za spoje plošč in cevi. Poleg svojega klasičnega pomena izraz »cev«, kot je uporabljen v tem dokumentu, zajema tudi druga cilindrična telesa, kot so dovodni kanali, bobni kotlov in tlačne posode.
Ta dokument določa zahteve za zaznavanje nepravilnosti zvarjenih spojev pri kovinskih ploščah in ceveh z digitalnim radiografskim preskušanjem z rentgenskimi ali gama žarki z uporabo računalniške radiografije (CR) ali radiografije z digitalnimi detektorskimi nizi (DDA). Vključuje ročni in avtomatizirani pregled z digitalnimi detektorskimi nizi.
Digitalni detektorji zagotavljajo digitalno sivinsko sliko, ki jo je mogoče prikazati in oceniti prek računalnika (dodatek E). Ta dokument določa priporočen postopek za izbiro detektorja in radiografsko prakso. Izbira računalnika, programske opreme, monitorja, tiskalnika in pogojev prikaza je pomembna, vendar ni ključni del tega dokumenta. Postopek, določen v tem dokumentu, zagotavlja minimalne zahteve za radiografsko prakso, ki omogočajo izpostavljenost in pridobivanje digitalnih rentgenskih slik z občutljivostjo zaznavanja nepravilnosti, enako kot pri radiografskem filmu (iz standarda ISO 17636-1).
Ta dokument ne določa stopenj sprejemljivosti za indikacije na digitalnih rentgenskih slikah. Standard ISO 10675 podaja informacije o stopnjah sprejemljivosti za pregled zvarnih spojev.
Če pogodbene stranke uporabijo nizka preskusna merila, bo dosežena kakovost morda znatno nižja od kakovosti, dosežene s strogim upoštevanjem tega dokumenta.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2023
Nadomešča:
SIST EN ISO 17636-2:2013
Neporušitveno preskušanje zvarnih spojev - Radiografsko preskušanje - 2. del:
Tehnike z rentgenskimi in gama žarki z uporabo digitalnih detektorjev (ISO 17636-
2:2022)
Non-destructive testing of welds - Radiographic testing - Part 2: X- and gamma-ray
techniques with digital detectors (ISO 17636-2:2022)
Zerstörungsfreie Prüfung von Schweißverbindungen - Durchstrahlungsprüfung - Teil 2:
Röntgen- und Gammastrahlungstechniken mit digitalen Detektoren (ISO 17636-2:2022)
Essais non destructifs des assemblages soudés - Contrôle par radiographie - Partie 2:
Techniques par rayons X ou gamma à l'aide de détecteurs numériques (ISO 17636-
2:2022)
Ta slovenski standard je istoveten z: EN ISO 17636-2:2022
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 17636-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 25.160.40 Supersedes EN ISO 17636-2:2013
English Version
Non-destructive testing of welds - Radiographic testing -
Part 2: X- and gamma-ray techniques with digital detectors
(ISO 17636-2:2022)
Essais non destructifs des assemblages soudés - Zerstörungsfreie Prüfung von Schweißverbindungen -
Contrôle par radiographie - Partie 2: Techniques par Durchstrahlungsprüfung - Teil 2: Röntgen- und
rayons X ou gamma à l'aide de détecteurs numériques Gammastrahlungstechniken mit digitalen Detektoren
(ISO 17636-2:2022) (ISO 17636-2:2022)
This European Standard was approved by CEN on 23 August 2022.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17636-2:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 17636-2:2022) has been prepared by Technical Committee ISO/TC 44 "Welding
and allied processes" in collaboration with Technical Committee CEN/TC 121 “Welding and allied
processes” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2023, and conflicting national standards shall be
withdrawn at the latest by April 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 17636-2:2013.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 17636-2:2022 has been approved by CEN as EN ISO 17636-2:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 17636-2
Second edition
2022-09
Non-destructive testing of welds —
Radiographic testing —
Part 2:
X- and gamma-ray techniques with
digital detectors
Essais non destructifs des assemblages soudés — Contrôle par
radiographie —
Partie 2: Techniques par rayons X ou gamma à l'aide de détecteurs
numériques
Reference number
ISO 17636-2:2022(E)
ISO 17636-2:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 17636-2:2022(E)
Contents Page
Foreword .v
1 S c op e . 1
2 Nor m at i ve r ef er enc e s . 1
3 Terms and definitions . 2
4 S ymbols and abbreviated terms.6
5 Classification of radiographic techniques and compensation principles .8
5.1 C lassification . 8
5.2 C ompensation principles, CP I, CP II or CP III . 8
5.2.1 G eneral . 8
5.2.2 C ompensation principle I (CP I) . 8
5.2.3 C ompensation principle II (CP II) . 8
5.2.4 C ompensation principle III (CP III) . 8
5 . 2 . 5 T he or e t ic a l b ac k g r ou nd . 9
6 General preparations and requirements . 9
6.1 Protection against ionizing radiation . 9
6.2 S urface preparation and stage of manufacture . 9
6.3 L ocation of the weld in the radiograph . 9
6.4 I dentification of radiographs . 9
6 . 5 M a rk i n g . 9
6.6 O verlap of digital images . 10
6.7 T ypes and positions of image quality indicators (IQIs) . 10
6.7.1 General . 10
6.7.2 Duplex wire IQIs. 10
6.7.3 Single wire or step-hole IQIs . 10
6.8 E valuation of image quality . 11
6.9 M inimum image quality values.12
6.10 Personnel qualification . 12
7 R e c om mende d t e c h n ique s .13
7.1 Te s t a r r a n g ement s . 13
7.1.1 G eneral .13
7.1.2 S ingle-wall penetration of plane objects (see Figure 1) . 14
7.1.3 S ingle-wall penetration of curved objects with the source outside the
object (see Figures 2 to 4) . 14
7.1.4 S ingle-wall penetration of curved objects with the source inside the object
for panoramic exposure (see Figures 5 to 7) . 15
7.1.5 Single-wall penetration of curved objects with the source located off-
centre and inside the object (see Figures 8 to 10) . 16
7.1.6 Double-wall penetration and double-image evaluation (DWDI) of pipes
with the elliptic technique and the source and the detector outside the
object (see Figure 11) . 17
7.1.7 Double-wall penetration and double-image evaluation (DWDI) with the
perpendicular technique and source and detector outside the object (see
Figure 12) . 17
7.1.8 D ouble-wall penetration and single-image evaluation (DWSI) of curved
objects for evaluation of the wall next to the detector (see Figures 13 to 16). 18
7.1.9 P enetration of objects with different material thicknesses (see Figure 17
to 19) . 19
7.2 C hoice of tube voltage and radiation source . 20
7.2.1 X -ray devices up to 1 000 kV . 20
7.2.2 O ther radiation sources . 21
7.3 D etector systems and metal screens . 22
7.3.1 Minimum normalized signal-to-noise ratio (SNR ) .22
N
iii
ISO 17636-2:2022(E)
7.3.2 C ompensation principle II . 25
7.3.3 Metal screens for IPs and shielding . 25
7.4 A lignment of beam . 25
7.5 R eduction of scattered radiation . 26
7.5.1 Metal filters and collimators . 26
7.5.2 Interception of backscattered radiation . 26
7. 6 S ou r c e -t o-obje c t d is t a nc e .26
7.7 Geometric magnification technique . 33
7.8 M aximum area for a single exposure .34
7.9 P r o c e s s i n g .34
7.9.1 S can and read-out of images .34
7.9.2 C orrection of acquired DDA images . 35
7.9.3 B ad pixel interpolation . 35
7.9.4 I m a g e pr o c e s s i n g . 35
7.10 M onitor viewing conditions and storage of digital radiographs .36
8 Te s t r ep or t .36
Annex A (normative) Number of exposures for acceptable testing of a circumferential butt
weld .38
Annex B (normative) Minimum image quality values .43
Annex C (normative) Determination of basic spatial resolution .51
Annex D (informative) Determination of minimum grey values for CR practice .53
Annex E (informative) Grey values — General remarks .58
Annex F (informative) Considering the detector unsharpness for f .60
min
Annex G (informative) Calculation of recommended X-ray tube voltages from Figure 20 .63
Bibliography .64
iv
ISO 17636-2:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 44, Welding and allied processes,
Subcommittee SC 5, Testing and inspection of welds, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 121, Welding and allied processes, in accordance
with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 17636-2:2013), which has been technically
revised.
The main changes are as follows:
— the normative references have been updated;
— the figures have been updated;
— manual and automated inspection with DDAs has been considered in 6.6, 6.7, and 7.8;
— references to Figures 1 to 19 have been updated throughout the document;
— in 6.7 a), the acceptance of a wire visibility shorter than 10 mm for pipes with an external
diameter < 50 mm has been added;
— in 6.7.1, the use of ASTM wires and other IQIs by agreement of the contracting parties has been
added;
— 6.8, “Evaluation of image quality” for digital radiography has been added;
— in 6.9 and 7.2.2, the lower thickness limit for Se-75 applications has been deleted;
— in 6.8, 6.9 and 7.3.1, a clarification for the IQI usage for DWDI technique has been added;
— permission to reduce SNR if the tube voltage is reduced or energy-resolving detectors are used
N
to < 80 % of the values given in Figure 20 has been added in 7.3.1;
v
ISO 17636-2:2022(E)
— in 7.3.2, the compensation principle II (CP II) has been extended to three wire pairs without the
agreement of the contracting parties;
— Annex C has been shortened to avoid duplication with ISO 19232-5;
— in D.2, a new note on fading has been added;
— a new Annex F has been added;
— a new Annex G has been added.
A list of all parts in the ISO 17636 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html. Official
interpretations of ISO/TC 44 documents, where they exist, are available from this page:
https://committee.iso.org/sites/tc44/home/interpretation.html.
vi
INTERNATIONAL STANDARD ISO 17636-2:2022(E)
Non-destructive testing of welds — Radiographic testing —
Part 2:
X- and gamma-ray techniques with digital detectors
1 S cope
This document specifies techniques of digital radiography with the object of enabling satisfactory and
repeatable results. The techniques are based on generally recognized practice and fundamental theory
of the subject.
This document applies to the digital radiographic testing of fusion welded joints in metallic materials.
It applies to the joints of plates and pipes. Besides its conventional meaning, “pipe”, as used in this
document, covers other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels.
This document specifies the requirements for digital radiographic X- and gamma-ray testing by either
computed radiography (CR) or radiography with digital detector arrays (DDAs) of the welded joints
of metallic plates and tubes for the detection of imperfections. It includes manual and automated
inspection with DDAs.
Digital detectors provide a digital grey value image which can be viewed and evaluated using a
computer (Annex E). This document specifies the recommended procedure for detector selection and
radiographic practice. Selection of computer, software, monitor, printer and viewing conditions are
important, but are not the main focus of this document. The procedure specified in this document
provides the minimum requirements for radiographic practice which permits exposure and acquisition
of digital radiographs with equivalent sensitivity for the detection of imperfections as film radiography
(specified in ISO 17636-1).
This document does not specify acceptance levels for any of the indications found on the digital
radiographs. ISO 10675 provides information on acceptance levels for weld inspection.
If contracting parties apply lower test criteria, it is possible that the quality achieved will be significantly
lower than when this document is strictly applied.
2 Normat ive references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 5576, Non-destructive testing — Industrial X-ray and gamma-ray radiology — Vocabulary
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO 16371-1:2011, 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
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
ISO 19232-4, Non-destructive testing — Image quality of radiographs — Part 4: Experimental evaluation
of image quality values and image quality tables
ISO 17636-2:2022(E)
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
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
ASTM E747, Standard Practice for Design, Manufacture and Material Grouping Classification of Wire Image
Quality Indicators (IQI) Used for Radiology
JIS Z2306, Radiographic image quality indicators for non-destructive testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5576 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
computed radiography
CR
complete system comprising a storage phosphor imaging plate (IP) (3.2) and a corresponding read-out
unit (scanner or reader), which converts the information from the IP into a digital image
3.2
storage phosphor imaging plate
IP
photostimulable luminescent material capable of storing a latent radiographic image of a material
being tested and which, upon stimulation by a source of red light of appropriate wavelength, generates
luminescence proportional to radiation absorbed
Note 1 to entry: When performing computed radiography (3.1), an IP is used in lieu of a film. When establishing
techniques related to source size (3.20) or focal geometries, the IP is referred to as a detector, i.e. source-to-
detector distance (3.21).
3.3
digital detector array
DDA
electronic device converting ionizing or penetrating radiation into a discrete array of analogue
signals which are subsequently digitized and transferred to a computer for display as a digital image
corresponding to the radiologic energy pattern imparted upon the input region of the device
3.4
structure noise
local sensitivity variations due to inhomogeneities in the sensitive layer (structure,
graininess) and surface of an imaging plate
Note 1 to entry: After scanning of the exposed imaging plate, the inhomogeneities appear as overlaid fixed
pattern noise in the digital image.
Note 2 to entry: This noise limits the maximum achievable image quality of digital CR images and can be
compared with the graininess in film images.
ISO 17636-2:2022(E)
3.5
structure noise
local sensitivity variations due to different properties of detector elements
(pixels)
Note 1 to entry: After read-out of the exposed uncorrected digital detector array (DDA) (3.3) image, the
inhomogeneities of the DDA appear as overlaid fixed pattern noise in the digital image. Therefore, all DDAs
require, after read-out, a software-based image correction (software and guidelines are provided by the
manufacturer). A suitable correction procedure reduces the structure noise.
Note 2 to entry: The image correction is also called “calibration” in other documents.
3.6
grey value
GV
numeric value of a pixel in a digital image
Note 1 to entry: This is typically interchangeable with the terms “pixel value”, “detector response”, “analogue-to-
digital unit” and “detector signal”.
Note 2 to entry: For further information, see Annex E.
3.7
linearized grey value
numeric value of a pixel which is directly proportional to the detector exposure dose, having a value of
zero if the detector was not exposed
Note 1 to entry: This is typically interchangeable with the terms “linearized pixel value” and “linearized detector
signal”.
3.8
basic spatial resolution of a digital detector
detector
SR
b
half of the measured detector unsharpness in a digital image, which corresponds to the effective pixel
size and indicates the smallest geometrical detail which can be resolved with a digital detector at
magnification equal to one
Note 1 to entry: For this measurement, the duplex wire IQI is placed directly on the digital detector array (3.3) or
imaging plate.
Note 2 to entry: The measurement of unsharpness is described in ISO 19232-5. See also ASTM E1000 and
ASTM E2736.
3.9
basic spatial resolution of a digital image
image
SR
b
half of the measured image unsharpness in a digital image, which corresponds to the effective pixel size
and indicates the smallest geometrical detail which can be resolved in a digital image
Note 1 to entry: For this measurement, the duplex wire IQI is placed directly on the object (source side).
Note 2 to entry: The measurement of unsharpness is described in ISO 19232-5. See also ASTM E1000 and
ASTM E2736.
3.10
signal-to-noise ratio
SNR
ratio of mean value of the linearized grey values (3.7) to the standard deviation of the linearized grey
values (noise) in a given region of interest (3.25) in a digital image
ISO 17636-2:2022(E)
3.11
normalized signal-to-noise ratio
SNR
N
image
signal-to-noise ratio (3.10) normalized by the basic spatial resolution of a digital image, SR , (3.9)
b
and calculated from the measured signal-to-noise ratio by:
88,6
SNRS=⋅ NR
N
image
SR
b
image
Note 1 to entry: If the duplex wire IQI is positioned directly on the detector without a test object, SR is equal
b
detector image
to the measured SR , which can be used instead of SR .
b b
3.12
contrast-to-noise ratio
CNR
ratio of the difference of the mean signal levels between two image areas to the averaged standard
deviation of the signal levels
Note 1 to entry: Signal levels are measured in grey values (3.6) or linearized grey values (3.7).
Note 2 to entry: The contrast-to-noise ratio describes a component of image quality and depends approximately
on the product of radiographic attenuation coefficient and SNR. In addition to adequate CNR, it is also necessary
for a digital radiograph to possess adequate unsharpness or basic spatial resolution to resolve desired features
of interest.
3.13
normalized contrast-to-noise ratio
CNR
N
image
contrast-to-noise ratio (3.12) normalized by the basic spatial resolution of a digital image, SR , (3.9),
b
as measured directly in the digital image with the duplex wire IQI on the object side and calculated
from the measured contrast-to-noise ratio, CNR, i.e.
88,6
CNRC=⋅NR
N
image
SR
b
3.14
aliasing
artefacts that appear in an image when the spatial frequency of the input is higher than the output is
capable of reproducing
Note 1 to entry: Aliasing often appears as jagged or stepped sections in a line or as moiré patterns.
3.15
cluster kernel pixel
CKP
bad pixel (3.29) which does not have five or more good neighbourhood pixels
Note 1 to entry: See ASTM E2597 for details of bad pixels and CKP.
3.16
nominal thickness
t
thickness of the parent material only where manufacturing tolerances do not have to be considered
3.17
penetration thickness change
Δt
change of penetrated thickness (3.18) relative to the nominal thickness (3.16) due to beam angle
ISO 17636-2:2022(E)
3.18
penetrated thickness
w
thickness of material in the direction of the radiation beam, calculated on the basis of the nominal
thicknesses (3.16) of all penetrated walls
3.19
object-to-detector distance
b
largest (maximum) distance between the radiation side of the radiographed part of the test object and
the sensitive layer of the detector, measured along the central axis of the radiation beam
Note 1 to entry: The abbreviated term ODD is used in other documents.
3.20
source size
d
size of the radiation source or focal spot size
Note 1 to entry: See EN 12543 or EN 12679.
3.21
source-to-detector distance
SDD
distance between the source of radiation and the detector, measured in the direction of the beam
Note 1 to entry: SDD = f + b
where
f is source-to-object distance (3.22);
b is object-to-detector distance (3.19).
3.22
source-to-object distance
f
distance between the source of radiation and the source side of the test object, measured along the
central axis of the radiation beam
Note 1 to entry: The abbreviated term SOD is used in other documents.
3.23
external diameter
D
e
nominal value of the external diameter of the pipe
3.24
geometric magnification
v
ratio of source-to-detector distance (3.21) to source-to-object distance (3.22)
3.25
region of interest
RoI
defined group of pixels from which measurements or statistics, or both, can be derived
ISO 17636-2:2022(E)
3.26
weld area to evaluate
WAE
area to be evaluated on the radiograph, which contains the weld and the heat-affected zone (3.30) on
both sides
3.27
area of interest
AoI
minimum area which should be evaluated on the radiograph and which contains the weld, the heat-
affected zone (3.30) on both sides and all lead letters, markers and image quality indicators (IQIs)
3.28
raw image
image acquired with digital detector arrays (3.3) or computed radiography (3.1) systems after image
correction, if a correction has been performed
3.29
bad pixel
underperforming detector element (pixel) of a digital detector array (3.3)
Note 1 to entry: Bad pixels are described in ASTM E2597.
3.30
heat affected zone
HAZ
area beside the weld influenced by the heating and cooling process of the welding, which is considered
as the two areas beside the weld, each with the same width as the weld cap but at least 10 mm width to
be considered for evaluation
4 S ymbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in Table 1 apply.
Table 1 — Symbols and abbreviated terms
Symbol or Definition
abbreviated
term
α angle subtended by half of the circumferential length of the AoI at the pipe centre, see Figure 22 a)
AoI area of interest
β opening angle of source window or collimator to central beam
b object-to-detector distance
b’ object-to-detector distance perpendicular to test object
b maximum distance from the object surface nearest to the planar detector to the object surface
ed
most distant to the detector in the weld area to evaluate (WAE) of the pipe, see Figures 2 b), 8 b),
13 b), 14 b) and 22
b distance between the radiation sensitive layer of the detector and the outer pipe surface, see
gap
Figures 2 b) and 22
C factor to correct f for using planar detectors for curved objects, if b > t
i min
CKP cluster kernel pixel
CNR contrast-to-noise ratio
CNR normalized contrast-to-noise ratio
N
CR computed radiography
d source size, focal spot size (see the EN 12543 series and EN 12679)
ISO 17636-2:2022(E)
Table 1 (continued)
Symbol or Definition
abbreviated
term
D detector
D external diameter
e
DDA digital detector array
DWDI double-wall double-image
DWSI double-wall single-image
f source-to-object distance
f minimum source-to-object distance
min
f* minimum source-to-object distance for testing of curved objects with planar detectors
min
f′ source-to-object distance perpendicular to test object
GV grey value
HAZ heat-affected zone
IP storage phosphor imaging plate
IQI image quality indicator
r external radius
e
r internal radius
i
RoI region of interest
S radiation source
SDD source-to-detector distance
SNR signal-to-noise ratio
SNR normalized signal-to-noise ratio
N
image detector
SR basic spatial resolution which can be SR or SR
b b b
detector
SR basic spatial resolution of a digital detector
b
image
SR basic spatial resolution of a digital image
b
t nominal thickness
Δt penetration thickness change
u geometric unsharpness
G
u inherent unsharpness of the detector system, excluding any geometric unsharpness, measured
d
from the digital image with a duplex wire IQI adjacent to the detector
U image unsharpness, measured in the digital image at the object plane with a duplex wire IQI
Im
u total image unsharpness, including geometric unsharpness, measured in the digital image at the
T
detector plane with a duplex wire IQI at the object plane
v geometric magnification
v optimum magnification
o
w penetrated thickness
WAE weld area to evaluate
NOTE The source-to-detector-distance (SDD), as used in digital radiography, is equivalent to SFD (see
ISO 17636-1) in film radiography.
ISO 17636-2:2022(E)
5 Classification of radiographic techniques and compensation principles
5.1 Classification
The radiographic techniques are divided into two testing classes:
— testing class A: basic techniques;
— testing class B: improved techniques.
Testing class B techniques are used when testing class A techniques are insufficiently sensitive.
Radiographic techniques providing higher sensitivity than testing class B are possible and may be
agreed between the contracting parties by specification of all appropriate test parameters.
The choice of digital radiographic technique shall be agreed between the contracting parties.
The visibility of flaws using film radiography or digital radiography is equivalent when using testing
class A and testing class B techniques, respectively. The visibility shall be proven by the use of IQIs
according to ISO 19232-1 or ISO 19232-2 and ISO 19232-5.
If, for technical or industrial reasons, it is not possible to meet one of the conditions specified for testing
class B, such as the type of radiation source or the source-to-object distance, f, it may be agreed by
contracting parties that the condition selected can be that specified for testing class A. The loss of
sensitivity shall be compensated by an increase of minimum grey value and SNR for CR or SNR for
N N
the DDA technique (recommended increase of SNR by a factor > 1,4). Because of the better sensitivity
N
than that of testing class A, the test specimen may be regarded as being tested to testing class B if the
correct IQI sensitivity is achieved. This does not apply if the special SDD reduction as described in 7.6
for test arrangements 7.1.4 and 7.1.5 (Figure 5 to Figure 10) are used.
5.2 C ompensation principles, CP I, CP II or CP III
5.2.1 General
Three compensation principles (see 5.2.2 to 5.2.4) are applied in this document for radiography with
digital detectors to achieve a sufficient contrast sensitivity.
Application of these principles requires the achievement of a minimum contrast-to-noise ratio, CNR ,
N
normalized to the detector basic spatial resolution per detectable material thickness difference Δw. If
the required normalized contrast-to-noise ratio (CNR per Δw) cannot be achieved due to an insufficient
N
value of one of the following parameters, this can be compensated by an increase in the SNR.
5.2.2 Compensation principle I (CP I)
Compensation for reduced contrast (e.g. by increased tube voltage) by increased SNR (e.g. by increased
tube current or exposure time).
5.2.3 Compensation principle II (CP II)
Compensation for insufficient detector sharpness (the value of SR is higher than specified) by increased
b
SNR (increase in the single IQI wire or step-hole value for each missing duplex wire pair value). SR
b
detector image
is SR for detector selection (IQI on the detector without object) or SR for image quality
b b
evaluation of a production radiograph with the IQI on the source side of the object.
5.2.4 Compensation principle III (CP III)
Compensation for increased local interpolation unsharpness, due to bad pixel correction for DDAs, by
increased SNR.
ISO 17636-2:2022(E)
5.2.5 Theoretical background
These compensation principles are based on the approximation given in Formula (1) for small flaw
sizes (Δw << w):
CNR μ ⋅SNR
N eff
=⋅c (1)
image
Δw
SR
b
where
c is a constant (0,088 6 mm);
µ is the effective attenuation coefficient, which is equivalent to the specific material contrast,
eff
−1
in mm ;
CNR is the normalized CNR, as measured in the digital image;
N
image
SR is the basic spatial image resolution, in mm.
b
6 Gener al preparations and requirements
6.1 Pr otection against ionizing radiation
WARNING — Exposure of any part of the human body to X-rays or gamma rays can be highly
injurious to health. Wherever X-ray equipment or radioactive sources are in use, appropriate
health and safety requirements shall be applied.
NOTE Local, national and international regulations and safety precautions provide additional information.
6.2 Surfac e preparation and stage of manufacture
In general, surface preparation is not necessary, but where surface imperfections or coatings can cause
difficulty in detecting defects, the surface shall be ground smooth or the coatings shall be removed.
Unless otherwise specified, digital radiography shall be carried out after the final stage of manufacture,
e.g. after grinding or heat treatment.
6.3 Location of the w eld in the radiograph
Where the digital radiograph does not show the weld, high-density markers shall be placed on both
sides of the weld outside the weld area to evaluate (WAE).
6.4 Identification of radiographs
Symbols sha
...
SLOVENSKI STANDARD
01-marec-2023
Nadomešča:
SIST EN ISO 17636-2:2013
Neporušitveno preskušanje zvarnih spojev - Radiografsko preiskušanje - 2. del:
Tehnike z rentgenskimi in gama žarki z uporabo digitalnih detektorjev (ISO 17636-
2:2022)
Non-destructive testing of welds - Radiographic testing - Part 2: X- and gamma-ray
techniques with digital detectors (ISO 17636-2:2022)
Zerstörungsfreie Prüfung von Schweißverbindungen - Durchstrahlungsprüfung - Teil 2:
Röntgen- und Gammastrahlungstechniken mit digitalen Detektoren (ISO 17636-2:2022)
Essais non destructifs des assemblages soudés - Contrôle par radiographie - Partie 2:
Techniques par rayons X ou gamma à l'aide de détecteurs numériques (ISO 17636-
2:2022)
Ta slovenski standard je istoveten z: EN ISO 17636-2:2022
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 17636-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 25.160.40 Supersedes EN ISO 17636-2:2013
English Version
Non-destructive testing of welds - Radiographic testing -
Part 2: X- and gamma-ray techniques with digital detectors
(ISO 17636-2:2022)
Essais non destructifs des assemblages soudés - Zerstörungsfreie Prüfung von Schweißverbindungen -
Contrôle par radiographie - Partie 2: Techniques par Durchstrahlungsprüfung - Teil 2: Röntgen- und
rayons X ou gamma à l'aide de détecteurs numériques Gammastrahlungstechniken mit digitalen Detektoren
(ISO 17636-2:2022) (ISO 17636-2:2022)
This European Standard was approved by CEN on 23 August 2022.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17636-2:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 17636-2:2022) has been prepared by Technical Committee ISO/TC 44 "Welding
and allied processes" in collaboration with Technical Committee CEN/TC 121 “Welding and allied
processes” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2023, and conflicting national standards shall be
withdrawn at the latest by April 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 17636-2:2013.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 17636-2:2022 has been approved by CEN as EN ISO 17636-2:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 17636-2
Second edition
2022-09
Non-destructive testing of welds —
Radiographic testing —
Part 2:
X- and gamma-ray techniques with
digital detectors
Essais non destructifs des assemblages soudés — Contrôle par
radiographie —
Partie 2: Techniques par rayons X ou gamma à l'aide de détecteurs
numériques
Reference number
ISO 17636-2:2022(E)
ISO 17636-2:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 17636-2:2022(E)
Contents Page
Foreword .v
1 S c op e . 1
2 Nor m at i ve r ef er enc e s . 1
3 Terms and definitions . 2
4 S ymbols and abbreviated terms.6
5 Classification of radiographic techniques and compensation principles .8
5.1 C lassification . 8
5.2 C ompensation principles, CP I, CP II or CP III . 8
5.2.1 G eneral . 8
5.2.2 C ompensation principle I (CP I) . 8
5.2.3 C ompensation principle II (CP II) . 8
5.2.4 C ompensation principle III (CP III) . 8
5 . 2 . 5 T he or e t ic a l b ac k g r ou nd . 9
6 General preparations and requirements . 9
6.1 Protection against ionizing radiation . 9
6.2 S urface preparation and stage of manufacture . 9
6.3 L ocation of the weld in the radiograph . 9
6.4 I dentification of radiographs . 9
6 . 5 M a rk i n g . 9
6.6 O verlap of digital images . 10
6.7 T ypes and positions of image quality indicators (IQIs) . 10
6.7.1 General . 10
6.7.2 Duplex wire IQIs. 10
6.7.3 Single wire or step-hole IQIs . 10
6.8 E valuation of image quality . 11
6.9 M inimum image quality values.12
6.10 Personnel qualification . 12
7 R e c om mende d t e c h n ique s .13
7.1 Te s t a r r a n g ement s . 13
7.1.1 G eneral .13
7.1.2 S ingle-wall penetration of plane objects (see Figure 1) . 14
7.1.3 S ingle-wall penetration of curved objects with the source outside the
object (see Figures 2 to 4) . 14
7.1.4 S ingle-wall penetration of curved objects with the source inside the object
for panoramic exposure (see Figures 5 to 7) . 15
7.1.5 Single-wall penetration of curved objects with the source located off-
centre and inside the object (see Figures 8 to 10) . 16
7.1.6 Double-wall penetration and double-image evaluation (DWDI) of pipes
with the elliptic technique and the source and the detector outside the
object (see Figure 11) . 17
7.1.7 Double-wall penetration and double-image evaluation (DWDI) with the
perpendicular technique and source and detector outside the object (see
Figure 12) . 17
7.1.8 D ouble-wall penetration and single-image evaluation (DWSI) of curved
objects for evaluation of the wall next to the detector (see Figures 13 to 16). 18
7.1.9 P enetration of objects with different material thicknesses (see Figure 17
to 19) . 19
7.2 C hoice of tube voltage and radiation source . 20
7.2.1 X -ray devices up to 1 000 kV . 20
7.2.2 O ther radiation sources . 21
7.3 D etector systems and metal screens . 22
7.3.1 Minimum normalized signal-to-noise ratio (SNR ) .22
N
iii
ISO 17636-2:2022(E)
7.3.2 C ompensation principle II . 25
7.3.3 Metal screens for IPs and shielding . 25
7.4 A lignment of beam . 25
7.5 R eduction of scattered radiation . 26
7.5.1 Metal filters and collimators . 26
7.5.2 Interception of backscattered radiation . 26
7. 6 S ou r c e -t o-obje c t d is t a nc e .26
7.7 Geometric magnification technique . 33
7.8 M aximum area for a single exposure .34
7.9 P r o c e s s i n g .34
7.9.1 S can and read-out of images .34
7.9.2 C orrection of acquired DDA images . 35
7.9.3 B ad pixel interpolation . 35
7.9.4 I m a g e pr o c e s s i n g . 35
7.10 M onitor viewing conditions and storage of digital radiographs .36
8 Te s t r ep or t .36
Annex A (normative) Number of exposures for acceptable testing of a circumferential butt
weld .38
Annex B (normative) Minimum image quality values .43
Annex C (normative) Determination of basic spatial resolution .51
Annex D (informative) Determination of minimum grey values for CR practice .53
Annex E (informative) Grey values — General remarks .58
Annex F (informative) Considering the detector unsharpness for f .60
min
Annex G (informative) Calculation of recommended X-ray tube voltages from Figure 20 .63
Bibliography .64
iv
ISO 17636-2:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 44, Welding and allied processes,
Subcommittee SC 5, Testing and inspection of welds, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 121, Welding and allied processes, in accordance
with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 17636-2:2013), which has been technically
revised.
The main changes are as follows:
— the normative references have been updated;
— the figures have been updated;
— manual and automated inspection with DDAs has been considered in 6.6, 6.7, and 7.8;
— references to Figures 1 to 19 have been updated throughout the document;
— in 6.7 a), the acceptance of a wire visibility shorter than 10 mm for pipes with an external
diameter < 50 mm has been added;
— in 6.7.1, the use of ASTM wires and other IQIs by agreement of the contracting parties has been
added;
— 6.8, “Evaluation of image quality” for digital radiography has been added;
— in 6.9 and 7.2.2, the lower thickness limit for Se-75 applications has been deleted;
— in 6.8, 6.9 and 7.3.1, a clarification for the IQI usage for DWDI technique has been added;
— permission to reduce SNR if the tube voltage is reduced or energy-resolving detectors are used
N
to < 80 % of the values given in Figure 20 has been added in 7.3.1;
v
ISO 17636-2:2022(E)
— in 7.3.2, the compensation principle II (CP II) has been extended to three wire pairs without the
agreement of the contracting parties;
— Annex C has been shortened to avoid duplication with ISO 19232-5;
— in D.2, a new note on fading has been added;
— a new Annex F has been added;
— a new Annex G has been added.
A list of all parts in the ISO 17636 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html. Official
interpretations of ISO/TC 44 documents, where they exist, are available from this page:
https://committee.iso.org/sites/tc44/home/interpretation.html.
vi
INTERNATIONAL STANDARD ISO 17636-2:2022(E)
Non-destructive testing of welds — Radiographic testing —
Part 2:
X- and gamma-ray techniques with digital detectors
1 S cope
This document specifies techniques of digital radiography with the object of enabling satisfactory and
repeatable results. The techniques are based on generally recognized practice and fundamental theory
of the subject.
This document applies to the digital radiographic testing of fusion welded joints in metallic materials.
It applies to the joints of plates and pipes. Besides its conventional meaning, “pipe”, as used in this
document, covers other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels.
This document specifies the requirements for digital radiographic X- and gamma-ray testing by either
computed radiography (CR) or radiography with digital detector arrays (DDAs) of the welded joints
of metallic plates and tubes for the detection of imperfections. It includes manual and automated
inspection with DDAs.
Digital detectors provide a digital grey value image which can be viewed and evaluated using a
computer (Annex E). This document specifies the recommended procedure for detector selection and
radiographic practice. Selection of computer, software, monitor, printer and viewing conditions are
important, but are not the main focus of this document. The procedure specified in this document
provides the minimum requirements for radiographic practice which permits exposure and acquisition
of digital radiographs with equivalent sensitivity for the detection of imperfections as film radiography
(specified in ISO 17636-1).
This document does not specify acceptance levels for any of the indications found on the digital
radiographs. ISO 10675 provides information on acceptance levels for weld inspection.
If contracting parties apply lower test criteria, it is possible that the quality achieved will be significantly
lower than when this document is strictly applied.
2 Normat ive references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 5576, Non-destructive testing — Industrial X-ray and gamma-ray radiology — Vocabulary
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO 16371-1:2011, 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
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
ISO 19232-4, Non-destructive testing — Image quality of radiographs — Part 4: Experimental evaluation
of image quality values and image quality tables
ISO 17636-2:2022(E)
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
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
ASTM E747, Standard Practice for Design, Manufacture and Material Grouping Classification of Wire Image
Quality Indicators (IQI) Used for Radiology
JIS Z2306, Radiographic image quality indicators for non-destructive testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5576 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
computed radiography
CR
complete system comprising a storage phosphor imaging plate (IP) (3.2) and a corresponding read-out
unit (scanner or reader), which converts the information from the IP into a digital image
3.2
storage phosphor imaging plate
IP
photostimulable luminescent material capable of storing a latent radiographic image of a material
being tested and which, upon stimulation by a source of red light of appropriate wavelength, generates
luminescence proportional to radiation absorbed
Note 1 to entry: When performing computed radiography (3.1), an IP is used in lieu of a film. When establishing
techniques related to source size (3.20) or focal geometries, the IP is referred to as a detector, i.e. source-to-
detector distance (3.21).
3.3
digital detector array
DDA
electronic device converting ionizing or penetrating radiation into a discrete array of analogue
signals which are subsequently digitized and transferred to a computer for display as a digital image
corresponding to the radiologic energy pattern imparted upon the input region of the device
3.4
structure noise
local sensitivity variations due to inhomogeneities in the sensitive layer (structure,
graininess) and surface of an imaging plate
Note 1 to entry: After scanning of the exposed imaging plate, the inhomogeneities appear as overlaid fixed
pattern noise in the digital image.
Note 2 to entry: This noise limits the maximum achievable image quality of digital CR images and can be
compared with the graininess in film images.
ISO 17636-2:2022(E)
3.5
structure noise
local sensitivity variations due to different properties of detector elements
(pixels)
Note 1 to entry: After read-out of the exposed uncorrected digital detector array (DDA) (3.3) image, the
inhomogeneities of the DDA appear as overlaid fixed pattern noise in the digital image. Therefore, all DDAs
require, after read-out, a software-based image correction (software and guidelines are provided by the
manufacturer). A suitable correction procedure reduces the structure noise.
Note 2 to entry: The image correction is also called “calibration” in other documents.
3.6
grey value
GV
numeric value of a pixel in a digital image
Note 1 to entry: This is typically interchangeable with the terms “pixel value”, “detector response”, “analogue-to-
digital unit” and “detector signal”.
Note 2 to entry: For further information, see Annex E.
3.7
linearized grey value
numeric value of a pixel which is directly proportional to the detector exposure dose, having a value of
zero if the detector was not exposed
Note 1 to entry: This is typically interchangeable with the terms “linearized pixel value” and “linearized detector
signal”.
3.8
basic spatial resolution of a digital detector
detector
SR
b
half of the measured detector unsharpness in a digital image, which corresponds to the effective pixel
size and indicates the smallest geometrical detail which can be resolved with a digital detector at
magnification equal to one
Note 1 to entry: For this measurement, the duplex wire IQI is placed directly on the digital detector array (3.3) or
imaging plate.
Note 2 to entry: The measurement of unsharpness is described in ISO 19232-5. See also ASTM E1000 and
ASTM E2736.
3.9
basic spatial resolution of a digital image
image
SR
b
half of the measured image unsharpness in a digital image, which corresponds to the effective pixel size
and indicates the smallest geometrical detail which can be resolved in a digital image
Note 1 to entry: For this measurement, the duplex wire IQI is placed directly on the object (source side).
Note 2 to entry: The measurement of unsharpness is described in ISO 19232-5. See also ASTM E1000 and
ASTM E2736.
3.10
signal-to-noise ratio
SNR
ratio of mean value of the linearized grey values (3.7) to the standard deviation of the linearized grey
values (noise) in a given region of interest (3.25) in a digital image
ISO 17636-2:2022(E)
3.11
normalized signal-to-noise ratio
SNR
N
image
signal-to-noise ratio (3.10) normalized by the basic spatial resolution of a digital image, SR , (3.9)
b
and calculated from the measured signal-to-noise ratio by:
88,6
SNRS=⋅ NR
N
image
SR
b
image
Note 1 to entry: If the duplex wire IQI is positioned directly on the detector without a test object, SR is equal
b
detector image
to the measured SR , which can be used instead of SR .
b b
3.12
contrast-to-noise ratio
CNR
ratio of the difference of the mean signal levels between two image areas to the averaged standard
deviation of the signal levels
Note 1 to entry: Signal levels are measured in grey values (3.6) or linearized grey values (3.7).
Note 2 to entry: The contrast-to-noise ratio describes a component of image quality and depends approximately
on the product of radiographic attenuation coefficient and SNR. In addition to adequate CNR, it is also necessary
for a digital radiograph to possess adequate unsharpness or basic spatial resolution to resolve desired features
of interest.
3.13
normalized contrast-to-noise ratio
CNR
N
image
contrast-to-noise ratio (3.12) normalized by the basic spatial resolution of a digital image, SR , (3.9),
b
as measured directly in the digital image with the duplex wire IQI on the object side and calculated
from the measured contrast-to-noise ratio, CNR, i.e.
88,6
CNRC=⋅NR
N
image
SR
b
3.14
aliasing
artefacts that appear in an image when the spatial frequency of the input is higher than the output is
capable of reproducing
Note 1 to entry: Aliasing often appears as jagged or stepped sections in a line or as moiré patterns.
3.15
cluster kernel pixel
CKP
bad pixel (3.29) which does not have five or more good neighbourhood pixels
Note 1 to entry: See ASTM E2597 for details of bad pixels and CKP.
3.16
nominal thickness
t
thickness of the parent material only where manufacturing tolerances do not have to be considered
3.17
penetration thickness change
Δt
change of penetrated thickness (3.18) relative to the nominal thickness (3.16) due to beam angle
ISO 17636-2:2022(E)
3.18
penetrated thickness
w
thickness of material in the direction of the radiation beam, calculated on the basis of the nominal
thicknesses (3.16) of all penetrated walls
3.19
object-to-detector distance
b
largest (maximum) distance between the radiation side of the radiographed part of the test object and
the sensitive layer of the detector, measured along the central axis of the radiation beam
Note 1 to entry: The abbreviated term ODD is used in other documents.
3.20
source size
d
size of the radiation source or focal spot size
Note 1 to entry: See EN 12543 or EN 12679.
3.21
source-to-detector distance
SDD
distance between the source of radiation and the detector, measured in the direction of the beam
Note 1 to entry: SDD = f + b
where
f is source-to-object distance (3.22);
b is object-to-detector distance (3.19).
3.22
source-to-object distance
f
distance between the source of radiation and the source side of the test object, measured along the
central axis of the radiation beam
Note 1 to entry: The abbreviated term SOD is used in other documents.
3.23
external diameter
D
e
nominal value of the external diameter of the pipe
3.24
geometric magnification
v
ratio of source-to-detector distance (3.21) to source-to-object distance (3.22)
3.25
region of interest
RoI
defined group of pixels from which measurements or statistics, or both, can be derived
ISO 17636-2:2022(E)
3.26
weld area to evaluate
WAE
area to be evaluated on the radiograph, which contains the weld and the heat-affected zone (3.30) on
both sides
3.27
area of interest
AoI
minimum area which should be evaluated on the radiograph and which contains the weld, the heat-
affected zone (3.30) on both sides and all lead letters, markers and image quality indicators (IQIs)
3.28
raw image
image acquired with digital detector arrays (3.3) or computed radiography (3.1) systems after image
correction, if a correction has been performed
3.29
bad pixel
underperforming detector element (pixel) of a digital detector array (3.3)
Note 1 to entry: Bad pixels are described in ASTM E2597.
3.30
heat affected zone
HAZ
area beside the weld influenced by the heating and cooling process of the welding, which is considered
as the two areas beside the weld, each with the same width as the weld cap but at least 10 mm width to
be considered for evaluation
4 S ymbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in Table 1 apply.
Table 1 — Symbols and abbreviated terms
Symbol or Definition
abbreviated
term
α angle subtended by half of the circumferential length of the AoI at the pipe centre, see Figure 22 a)
AoI area of interest
β opening angle of source window or collimator to central beam
b object-to-detector distance
b’ object-to-detector distance perpendicular to test object
b maximum distance from the object surface nearest to the planar detector to the object surface
ed
most distant to the detector in the weld area to evaluate (WAE) of the pipe, see Figures 2 b), 8 b),
13 b), 14 b) and 22
b distance between the radiation sensitive layer of the detector and the outer pipe surface, see
gap
Figures 2 b) and 22
C factor to correct f for using planar detectors for curved objects, if b > t
i min
CKP cluster kernel pixel
CNR contrast-to-noise ratio
CNR normalized contrast-to-noise ratio
N
CR computed radiography
d source size, focal spot size (see the EN 12543 series and EN 12679)
ISO 17636-2:2022(E)
Table 1 (continued)
Symbol or Definition
abbreviated
term
D detector
D external diameter
e
DDA digital detector array
DWDI double-wall double-image
DWSI double-wall single-image
f source-to-object distance
f minimum source-to-object distance
min
f* minimum source-to-object distance for testing of curved objects with planar detectors
min
f′ source-to-object distance perpendicular to test object
GV grey value
HAZ heat-affected zone
IP storage phosphor imaging plate
IQI image quality indicator
r external radius
e
r internal radius
i
RoI region of interest
S radiation source
SDD source-to-detector distance
SNR signal-to-noise ratio
SNR normalized signal-to-noise ratio
N
image detector
SR basic spatial resolution which can be SR or SR
b b b
detector
SR basic spatial resolution of a digital detector
b
image
SR basic spatial resolution of a digital image
b
t nominal thickness
Δt penetration thickness change
u geometric unsharpness
G
u inherent unsharpness of the detector system, excluding any geometric unsharpness, measured
d
from the digital image with a duplex wire IQI adjacent to the detector
U image unsharpness, measured in the digital image at the object plane with a duplex wire IQI
Im
u total image unsharpness, including geometric unsharpness, measured in the digital image at the
T
detector plane with a duplex wire IQI at the object plane
v geometric magnification
v optimum magnification
o
w penetrated thickness
WAE weld area to evaluate
NOTE The source-to-detector-distance (SDD), as used in digital radiography, is equivalent to SFD (see
ISO 17636-1) in film radiography.
ISO 17636-2:2022(E)
5 Classification of radiographic techniques and compensation principles
5.1 Classification
The radiographic techniques are divided into two testing classes:
— testing class A: basic techniques;
— testing class B: improved techniques.
Testing class B techniques are used when testing class A techniques are insufficiently sensitive.
Radiographic techniques providing higher sensitivity than testing class B are possible and may be
agreed between the contracting parties by specification of all appropriate test parameters.
The choice of digital radiographic technique shall be agreed between the contracting parties.
The visibility of flaws using film radiography or digital radiography is equivalent when using testing
class A and testing class B techniques, respectively. The visibility shall be proven by the use of IQIs
according to ISO 19232-1 or ISO 19232-2 and ISO 19232-5.
If, for technical or industrial reasons, it is not possible to meet one of the conditions specified for testing
class B, such as the type of radiation source or the source-to-object distance, f, it may be agreed by
contracting parties that the condition selected can be that specified for testing class A. The loss of
sensitivity shall be compensated by an increase of minimum grey value and SNR for CR or SNR for
N N
the DDA technique (recommended increase of SNR by a factor > 1,4). Because of the better sensitivity
N
than that of testing class A, the test specimen may be regarded as being tested to testing class B if the
correct IQI sensitivity is achieved. This does not apply if the special SDD reduction as described in 7.6
for test arrangements 7.1.4 and 7.1.5 (Figure 5 to Figure 10) are used.
5.2 C ompensation principles, CP I, CP II or CP III
5.2.1 General
Three compensation principles (see 5.2.2 to 5.2.4) are applied in this document for radiography with
digital detectors to achieve a sufficient contrast sensitivity.
Application of these principles requires the achievement of a minimum contrast-to-noise ratio, CNR ,
N
normalized to the detector basic spatial resolution per detectable material thickness difference Δw. If
the required normalized contrast-to-noise ratio (CNR per Δw) cannot be achieved due to an insufficient
N
value of one of the following parameters, this can be compensated by an increase in the SNR.
5.2.2 Compensation principle I (CP I)
Compensation for reduced contrast (e.g. by increased tube voltage) by increased SNR (e.g. by increased
tube current or exposure time).
5.2.3 Compensation principle II (CP II)
Compensation for insufficient detector sharpness (the value of SR is higher than specified) by increased
b
SNR (increase in the single IQI wire or step-hole value for each missing duplex wire pair value). SR
b
detector image
is SR for detector selection (IQI on the detector without object) or SR for image quality
b b
evaluation of a production radiograph with the IQI on the source side of the object.
5.2.4 Compensation principle III (CP III)
Compensation for increased local interpolation unsharpness, due to bad pixel correction for DDAs, by
increased SNR.
ISO 17636-2:2022(E)
5.2.5 Theoretical background
These compensation principles are based on the approximation given in Formula (1) for small flaw
sizes (Δw << w):
CNR μ ⋅SNR
N eff
=⋅c (1)
image
Δw
SR
b
where
c is a constant (0,088 6 mm);
µ is the effective attenuation coefficient, which is equivalent to the specific material contrast,
eff
−1
in mm ;
CNR is the normalized CNR, as measured in the digital image;
N
image
SR is the basic spatial image resolution, in mm.
b
6 Gener al preparations and requirements
6.1 Pr otection against ionizing radiation
WARNING — Exposure of any part of the human body to X-rays or gamma rays can be highly
injurious to health. Wherever X-ray equipment or radioactive sources are in use, appropriate
health and safety requirements shall be applied.
NOTE Local, national and international regulations and safety precautions provide additional information.
6.2 Surfac e preparation and stage of manufacture
In general, surface preparation is not necessary, but where surface imperfections or coatings can cause
difficulty in detecting defects, the surface shall be ground smooth or the coatings shall be removed.
Unless otherwise specified, digital radiography shall be carried out after the final stage of manufacture,
e.g. after grinding or heat treatment.
6.3 Location of the w eld in the radiograph
Where the digital radiograph does not show the weld, high-density markers shall be placed on both
sides of the weld outside the weld area to evaluate (WAE).
6.4 Identification of radiographs
Symbols sh
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