SIST EN 16407-1:2014
(Main)Non-destructive testing - Radiographic inspection of corrosion and deposits in pipes by X- and gamma rays - Part 1: Tangential radiographic inspection
Non-destructive testing - Radiographic inspection of corrosion and deposits in pipes by X- and gamma rays - Part 1: Tangential radiographic inspection
This European Standard specifies fundamental techniques of film and digital radiography with the object of enabling satisfactory and repeatable results to be obtained economically. The techniques are based on generally recognized practice and fundamental theory of the subject. This European Standard applies to the radiographic examination of pipes in metallic materials for service induced flaws such as corrosion pitting, generalized corrosion and erosion. Besides its conventional meaning, “pipe” as used in this standard should be understood to cover other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels. Weld inspection for typical welding process induced flaws is not covered, but weld inspection is included for corrosion/erosion type flaws. The pipes may be insulated or not, and can be assessed where loss of material due, for example, to corrosion or erosion is suspected either internally or externally. This part of EN 16407 covers the tangential inspection technique for detection and through-wall sizing of wall loss, including:
a) with the source on the pipe centre line, and
b) with the source offset from it by the pipe radius.
Part 2 of EN 16407 covers double wall radiography, and note that the double wall double image technique is often combined with tangential radiography with the source on the pipe centre line. This European Standard applies to tangential radiographic inspection using industrial radiographic film techniques, computed digital radiography (CR) and digital detector arrays (DDA).
Zerstörungsfreie Prüfung - Durchstrahlungsprüfung auf Korrosion und Ablagerungen in Rohren mit Röntgen- und Gammastrahlen - Teil 1: Tangentielle Durchstrahlungsprüfung
In diesem Teil werden grundlegende Techniken für die Durchstrahlungsprüfung unter Anwendung von Filmen und digitalen Techniken mit dem Ziel festgelegt, auf wirtschaftliche Art und Weise zuverlässige und wieder-holbare Ergebnisse zu erreichen. Die Techniken basieren sowohl auf den allgemein anerkannten Verfahren und den theoretischen Grundlagen dieses Fachgebiets.
Diese Norm gilt für die Durchstrahlungsprüfung von Rohren aus metallischen Werkstoffen zum Nachweis von Werkstofffehlern, die beim Gebrauch auftreten, z. B. Korrosionsmulden oder Fehler durch allgemeine Korrosi-on und Erosion. Neben der konventionellen Bedeutung sollten in dieser Norm unter der Benennung „Rohr“ (engl. pipe) auch andere zylindrische Gegenstände, z. B. Röhren/Schläuche, Druckrohrleitungen, Kessel-trommeln und Druckbehälter verstanden werden.
In dieser Norm nicht behandelt wird die Überprüfung von Schweißnähten auf die Fehler, die durch die herkömmlichen Schweißverfahren eingebracht werden; behandelt wird dagegen die Prüfung von Schweißver-bindungen zum Nachweis von Fehlern durch Korrosion/Erosion.
Die Prüfung kann an Rohren mit oder ohne Wärmedämmung durchgeführt werden, beispielsweise in den Fällen, in denen vermutet wird, dass durch Korrosion oder Erosion ein Materialverlust an der Innen oder Mantelfläche des Rohrs entstanden ist.
Dieser Teil der vorliegenden Norm behandelt das tangentiale Prüfverfahren zum Nachweis einer Verringerung der Dicke der Rohrwand und zur Bestimmung der Größenordnung dieser Dickenverringerung, die Anordnung der Strahlenquelle erfolgt a) in Höhe der Rohrachse oder b) versetzt zur Rohrachse, wobei der Abstand für die Versetzung gegenüber der Rohrachse dem Rohrradius entspricht.
Teil 2 der vorliegenden Norm erfasst die Doppelwand Durchstrahlung; es ist zu beachten, dass die Doppel-wand-Doppelbild Technik häufig mit einer tangentialen Durchstrahlung kombiniert wird, bei der die Strahlen-quelle in Höhe der Rohrachse angeordnet ist.
Diese Norm gilt für die tangentiale Durchstrahlungsprüfung unter Anwendung industrieller Röntgenfilmtech-niken, computerunterstützter digitaler Radiographie (CR) und digitaler Matrixdetektoren (DDA).
Essais non destructifs - Examen radiographique de la corrosion et des dépôts dans les canalisations, par rayons X et rayons gamma - Partie 1: Examen radiographique tangentiel
La présente Norme européenne spécifie les techniques fondamentales de radiographie sur film et de radiographie numérique permettant d'obtenir des résultats satisfaisants et reproductibles de manière économique. Les techniques reposent sur une pratique généralement reconnue et sur la théorie fondamentale en la matière.
La présente Norme européenne s'applique à l'examen radiographique des canalisations en matériaux métalliques afin de détecter des défauts induits par le service tels que piqûres de corrosion, corrosion généralisée et érosion. Outre sa signification conventionnelle, il convient de comprendre que le terme « canalisation », tel qu'il est utilisé dans la présente norme, couvre d'autres corps cylindriques tels que les tubes, les conduites forcées, les corps de chaudière et les récipients sous pression.
Le contrôle des soudures pour détecter les défauts types induits par le procédé de soudage n'est pas traité, mais un contrôle des soudures est inclus pour rechercher les défauts de type corrosion/érosion.
Les canalisations peuvent être isolées ou non et peuvent être évaluées lorsqu'une perte de matériau due, par exemple, à la corrosion ou à l'érosion, interne ou externe, est suspectée.
La présente partie de l'EN 16407 traite de la technique d'examen tangentiel permettant la détection et le dimensionnement d'une perte de paroi dans le sens de l’épaisseur, y compris :
a) à l'aide d'une source située sur la ligne médiane de la canalisation, et
b) à l'aide d'une source décalée par rapport à cette ligne d’une distance égale au rayon de la canalisation.
La Partie 2 de l'EN 16407 traite de l'examen radiographique double paroi et il convient de noter que la technique de double paroi double image est souvent combinée à une radiographie tangentielle avec la source située sur la ligne médiane de la canalisation.
La présente Norme européenne s'applique à l'examen radiographique tangentiel en utilisant des techniques industrielles sur film radiographique, la radiographie numérisée (CR) et des mosaïques de détecteurs numériques (DDA).
Neporušitvene preiskave - Radiografski pregled korozije in nanosov v ceveh z rentgenskimi in gama žarki - 1. del: Tangencialni radiografski pregled
Ta evropski standard določa temeljne tehnike filmske in digitalne radiografije z namenom omogočanja zadovoljivih in ponovljivih rezultatov, ki so stroškovno ugodni. Tehnike so osnovane na splošno priznani praksi in temeljnem poznavanju subjekta. Ta evropski standard velja za radiografski pregled cevi in kovinskih materialov za poškodbe, ki so posledica uporabe, kot na primer jamičasta korozija, splošna korozija in erozija. Poleg svojega klasičnega pomena izraz »cev«, kot je uporabljen v tem standardu, zajema tudi druga cilindrična telesa, kot so dovodni kanali, bobni kotlov in tlačne posode. Standard ne zajema pregleda zvarov za običajne napake, ki so posledica varilnega postopka, vključuje pa pregled zvarov za napake, ki so posledica korozije/erozije. Cevi so lahko izolirane ali ne in se jih lahko pregleda, če se sumi na notranjo ali zunanjo poškodbo materiala, ki je posledica korozije ali erozije. Ta del standarda EN 16407 zajema tehniko tangencialnega pregleda za odkrivanje in ugotavljanje obsega poškodbe sten, ki se izvede skozi steno, vključno z:
a) virom na središčnici cevi in
b) virom, odmaknjenim od središčnice za polmer cevi.
2. del standarda EN 16407 zajema radiografijo prek dveh sten. Dvoslikovna tehnika prek dveh sten se pogosto uporablja skupaj s tangencialno radiografijo z virom na središčnici cevi. Ta evropski standard velja za tangencialni radiografski pregled, ki uporablja tehnike industrijskega radiografskega filma, računalniško digitalno radiografijo (CR) ali radiografijo z digitalnimi detektorskimi nizi (DDA).
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Neporušitvene preiskave - Radiografski pregled korozije in nanosov v ceveh z rentgenskimi in gama žarki - 1. del: Tangencialni radiografski pregledZerstörungsfreie Prüfung - Durchstrahlungsprüfung auf Korrosion und Ablagerungen in Rohren mit Röntgen- und Gammastrahlen - Teil 1: Tangentielle DurchstrahlungsprüfungEssais non destructifs - Examen radiographique de la corrosion et des dépôts dans les canalisations, par rayons X et rayons gamma - Partie 1: Examen radiographique tangentielNon-destructive testing - Radiographic inspection of corrosion and deposits in pipes by X- and gamma rays - Part 1: Tangential radiographic inspection23.040.01Deli cevovodov in cevovodi na splošnoPipeline components and pipelines in general19.100Neporušitveno preskušanjeNon-destructive testingICS:Ta slovenski standard je istoveten z:EN 16407-1:2014SIST EN 16407-1:2014en,fr,de01-julij-2014SIST EN 16407-1:2014SLOVENSKI
STANDARD
SIST EN 16407-1:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16407-1
January 2014 ICS 19.100; 23.040.01 English Version
Non-destructive testing - Radiographic inspection of corrosion and deposits in pipes by X- and gamma rays - Part 1: Tangential radiographic inspection
Essais non destructifs - Examen radiographique de la corrosion et des dépôts dans les canalisations, par rayons X et rayons gamma - Partie 1: Examen radiographique tangentiel
Zerstörungsfreie Prüfung - Durchstrahlungsprüfung auf Korrosion und Ablagerungen in Rohren mit Röntgen- und Gammastrahlen - Teil 1: Tangentiale Durchstrahlungsprüfung This European Standard was approved by CEN on 26 October 2013.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16407-1:2014 ESIST EN 16407-1:2014
EN 16407-1:2014 (E) 2 Contents Page Foreword .4 1 Scope .5 2 Normative references .5 3 Terms and definitions .6 4 Classification of radiographic techniques .8 5 General .8 5.1 Protection against ionising radiation .8 5.2 Personnel qualification .9 5.3 Identification of radiographs .9 5.4 Marking .9 5.5 Overlap of films or digital images .9 5.6 Types and positions of image quality indicators (IQI) .9 5.6.1 Single wire or step hole IQIs .9 5.6.2 Duplex wire IQI (digital radiographs) .9 6 Recommended techniques for making radiographs . 10 6.1 Test arrangements . 10 6.1.1 General . 10 6.1.2 Radiation source located on the pipe centre line . 10 6.1.3 Radiation source located offset from the pipe centre line . 11 6.1.4 Alignment of beam and film/detector . 13 6.2 Choice of radiation source . 13 6.3 Film systems and metal screens. 14 6.4 Screens and shielding for imaging plates (computed radiography only) . 16 6.5 Reduction of scattered radiation . 17 6.5.1 Filters and collimators . 17 6.5.2 Interception of back scattered radiation . 18 6.6 Source-to-detector distance . 18 6.7 Axial coverage and overlap . 19 6.8 Dimensional comparators . 20 6.9 Image saturation and use of lead strips to avoid burn-off . 21 6.10 Selection of digital radiographic equipment . 21 6.10.1 General . 21 6.10.2 CR systems . 22 6.10.3 DDA systems . 22 7 Radiograph/digital image sensitivity, quality and evaluation . 22 7.1 Evaluation of image quality . 22 7.1.1 General . 22 7.1.2 Maximum grey level in free beam (digital radiographs) . 22 7.1.3 Minimum normalized signal to noise ratio (digital radiographs) . 22 7.2 Density of film radiographs . 23 7.3 Film processing . 23 7.4 Film viewing conditions . 23 7.5 Dimensional calibration of radiographs or digital images . 24 7.5.1 General . 24 7.5.2 Measurement of distances in radiographic setup . 24 7.5.3 Measurement of pipe outside diameter . 25 SIST EN 16407-1:2014
EN 16407-1:2014 (E) 3 7.5.4 Dimensional comparator . 25 7.6 Wall thickness measurements for film radiographs . 26 7.7 Wall thickness measurements for digital radiographs . 26 7.7.1 Interactive on-screen measurements . 26 7.7.2 Grey-level profile analysis methods . 26 8 Digital image recording, storage, processing and viewing . 27 8.1 Scan and read out of image. 27 8.2 Multi radiograph technique . 27 8.3 Calibration of DDAs . 28 8.4 Bad pixel interpolation . 28 8.5 Image processing . 28 8.6 Digital image recording and storage . 28 8.7 Monitor viewing conditions . 29 9 Test report . 29 Annex A (normative)
Determination of basic spatial resolution . 31 Annex B (informative)
Choice of radiation source for different pipes . 35 Bibliography . 36
SIST EN 16407-1:2014
EN 16407-1:2014 (E) 4 Foreword This document (EN 16407-1:2014) has been prepared by Technical Committee CEN/TC 138 “Non-destructive testing”, the secretariat of which is held by AFNOR. 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 July 2014, and conflicting national standards shall be withdrawn at the latest by July 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. EN 16407 consists of the following parts, under the general title Non-destructive testing — Radiographic inspection of corrosion and deposits in pipes by X- and gamma rays: — Part 1: Tangential radiographic inspection; — Part 2: Double wall radiographic inspection. 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16407-1:2014
EN 16407-1:2014 (E) 5 1 Scope This European Standard specifies fundamental techniques of film and digital radiography with the object of enabling satisfactory and repeatable results to be obtained economically. The techniques are based on generally recognized practice and fundamental theory of the subject. This European Standard applies to the radiographic examination of pipes in metallic materials for service induced flaws such as corrosion pitting, generalized corrosion and erosion. Besides its conventional meaning, “pipe” as used in this standard should be understood to cover other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels. Weld inspection for typical welding process induced flaws is not covered, but weld inspection is included for corrosion/erosion type flaws. The pipes may be insulated or not, and can be assessed where loss of material due, for example, to corrosion or erosion is suspected either internally or externally. This part of EN 16407 covers the tangential inspection technique for detection and through-wall sizing of wall loss, including: a) with the source on the pipe centre line, and b) with the source offset from it by the pipe radius. Part 2 of EN 16407 covers double wall radiography, and note that the double wall double image technique is often combined with tangential radiography with the source on the pipe centre line. This European Standard applies to tangential radiographic inspection using industrial radiographic film techniques, computed digital radiography (CR) and digital detector arrays (DDA). 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 14784-1, Non-destructive testing — Industrial computed radiography with storage phosphor imaging plates — Part 1: Classification of systems EN ISO 11699-1, Non-destructive testing — Industrial radiographic films — Part 1: Classification of film systems for industrial radiography (ISO 11699-1) EN ISO 11699-2, Non-destructive testing — Industrial radiographic films — Part 2: Control of film processing by means of reference values (ISO 11699-2) EN ISO 17636-1:2013, Non-destructive testing of welds — Radiographic testing — Part 1: X- and gamma-ray techniques with film (ISO 17636-1:2013) EN ISO 19232-5, Non-destructive testing — Image quality of radiographs — Part 5: Determination of the image unsharpness value using duplex wire-type image quality indicators (ISO 19232-5) SIST EN 16407-1:2014
EN 16407-1:2014 (E) 6 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 actual wall thickness tact actual wall thickness of the pipe 3.2 basic spatial resolution of a digital detector SRbdetector 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 or imaging plate. Note 2 to entry: The measurement of unsharpness is described in EN ISO 19232-5, see also ASTM E2736 [18] and ASTM E1000 [16]. 3.3 comparator C reference object of defined dimension c and material for dimensional calibration of a radiographic image 3.4 computed radiography CR storage phosphor imaging plate system complete system comprising a storage phosphor imaging plate (IP) and a corresponding read-out unit (scanner or reader), which converts the information from the IP into a digital image 3.5 detector D radiographic image detector consisting of a NDT film system (see EN ISO 11699-1) or a digital radiography system using an imaging plate system (CR system) or a DDA system Note 1 to entry: Film systems and IPs can be used as flexible and curved detectors or in planar cassettes. 3.6 digital detector array system DDA system electronic device converting ionizing or penetrating radiation into a discrete array of analogue signals which are subsequently digitised 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 3.7 maximum penetrated thickness wmax maximum thickness of material for a pipe which occurs for a tangent to the inner pipe surface SIST EN 16407-1:2014
EN 16407-1:2014 (E) 7 3.8 measured wall thickness tmeas measured wall thickness of the pipe on the radiograph or digital image 3.9 nominal wall thickness t thickness of the pipe material only where manufacturing tolerances do not have to be taken into account 3.10 normalized signal-to-noise ratio SNRN signal-to-noise ratio, SNR, normalised by the basic spatial resolution, SRb, as measured directly in the digital image and/or calculated from the measured SNR, SNRmeasured, by: Nmeasuredb88,6µmSNR=SNRSR 3.11 object-to-detector distance b distance between the radiation side of the test object and the detector surface measured along the central axis of the radiation beam 3.12 outside diameter De nominal outside diameter of the pipe 3.13 pipe centre to detector distance PDD distance between the pipe centre and the detector 3.14 pixel size geometrical centre-to-centre distance between adjacent pixels in a row (horizontal pitch) or column (vertical pitch) of the scanned image [SOURCE: EN 14096-2:2003, 3.2] 3.15 signal-to-noise ratio SNR ratio of mean value of the linearized grey values to the standard deviation of the linearized grey values (noise) in a given region of interest in a digital image 3.16 source size d size of the radiation source [SOURCE: EN 12679:1999, 2.1] SIST EN 16407-1:2014
EN 16407-1:2014 (E) 8 3.17 source-to-detector distance SDD distance between the source of radiation and the detector measured in the direction of the beam 3.18 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 3.19 source-to-pipe centre distance SPD distance between the source of radiation and the pipe centre (pipe axis) measured in the direction of the beam 3.20 storage phosphor 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 4 Classification of radiographic techniques The tangential radiographic techniques are divided into two classes: — basic technique TA; — improved technique TB. The basic techniques, TA, are intended for tangential radiography of generalized wall loss, such as that due to erosion or large scale corrosion. The improved techniques, TB, should be used for the more demanding tangential radiography of localized corrosion pitting flaws, which require higher sensitivity for detection and sizing. Further technique improvements beyond TB are possible and may be agreed between the contracting parties by specification of all appropriate test parameters. The choice of radiographic technique shall be agreed between the concerned parties. 5 General 5.1 Protection against ionising 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 legal requirements shall be applied. Local or national or international safety precautions when using ionizing radiation shall be strictly applied. SIST EN 16407-1:2014
EN 16407-1:2014 (E) 9 5.2 Personnel qualification Testing shall be carried out by proficient, suitably trained and qualified personnel and, where applicable, shall be supervised by competent personnel nominated by the employer or, by delegation of the employer, the inspection company in charge of testing. To demonstrate appropriate qualification it is recommended that personnel be certified according to EN ISO 9712 or an equivalent formalised system. Operating authorization for qualified persons shall be issued by the employer in accordance with a written procedure. NDT operations, unless otherwise agreed, shall be authorized by a competent and qualified NDT supervisory individual (Level 3 or equivalent) approved by the employer. The personnel shall prove additional training and qualification in digital industrial radiology if digital detectors are being used. 5.3 Identification of radiographs Symbols shall be affixed to each section of the object being radiographed. The images of these symbols shall appear in the radiograph outside the region of interest where possible and shall ensure unambiguous identification of the section. 5.4 Marking Permanent markings should be made on the object to be examined in order to accurately locate the position of each radiograph. Where the nature of the material and/or its service conditions do not permit permanent marking, the location may be recorded by means of accurate sketches. 5.5 Overlap of films or digital images When radiographing an area with two or more films or separate detectors, the films or detectors shall overlap sufficiently to ensure that the complete region of interest is radiographed. This shall be verified by a high density marker on the surface of the object which will appear on each film or detector. If the radiographs will be taken sequentially, the high density marker shall be visible on each of the radiographs. 5.6 Types and positions of image quality indicators (IQI) 5.6.1 Single wire or step hole IQIs For tangential radiography, single wire or step hole IQIs are not applicable. 5.6.2 Duplex wire IQI (digital radiographs) IQIs in accordance with EN ISO 19232-5 should be used for measurement of the basic spatial resolution of the CR/DDA system in a reference radiograph (see 7.1.3 and Annex A). The duplex wire IQI shall be placed adjacent to the imaging plate or detector array and positioned a few degrees tilted (2° to 5°) to the digital rows or columns of the digital image. SIST EN 16407-1:2014
EN 16407-1:2014 (E) 10 6 Recommended techniques for making radiographs 6.1 Test arrangements 6.1.1 General Normally radiographic techniques in accordance with 6.1.2 and 6.1.3 shall be used. For both techniques, the film or digital detector shall be placed as close to the pipe as possible. 6.1.2 Radiation source located on the pipe centre line For this arrangement the source is located in front of the pipe and with the film/detector at the opposite side, as shown in Figure 1. The pipe can be non insulated (Figure 1 a)) or insulated (Figure 1 b)).
a) non insulated pipe SIST EN 16407-1:2014
EN 16407-1:2014 (E) 11
b) insulated pipe Key 1 detector D Figure 1 — Test arrangement and distances for tangential radiography with the source on the pipe centre line Note that the wall loss can be located on either the inner diameter, outer diameter or both surfaces of the pipe. 6.1.3 Radiation source located offset from the pipe centre line For this arrangement, the radiation source is located in front of the pipe and with the film/detector at the opposite side, as shown in Figure 2 a) (non insulated pipe) and Figure 2 b) (insulated pipe). SIST EN 16407-1:2014
EN 16407-1:2014 (E) 12
a) non insulated pipe
b) insulated pipe Key 1 detector D Figure 2 — Test arrangement and distances for tangential radiography with the source offset from the pipe centre line SIST EN 16407-1:2014
EN 16407-1:2014 (E) 13 In this test arrangement, the source is offset from the pipe centre line, and is aligned with the centre of the pipe wall, as shown in Figure 2. Note that the wall loss can be located on either the inner diameter, outer diameter or both surfaces of the pipe. 6.1.4 Alignment of beam and film/detector The beam of radiation shall be directed at the centre of the area being examined. The film or detector should be aligned to be orthogonal to the centre of the radiation beam. Modifications to these alignments and the test arrangements given in 6.1.2 and 6.1.3 may be needed in special cases, due for example to the presence of obstructions. Other ways of radiographing may be agreed between contracting parties. 6.2 Choice of radiation source For tangential radiography, the choice of radiation source should be determined by the maximum penetrated thickness of the pipe, wmax, which occurs for the path forming a tangent to the pipe inner diameter, as shown in Figure 3.
Key 1 detector D Figure 3 — Maximum penetrated thickness, wmax, for the tangential technique The maximum penetrated thickness, wmax, is given by: maxe2()=−wDtt (1) where t is the nominal thickness of the pipe; De is the outside diameter of the pipe. SIST EN 16407-1:2014
EN 16407-1:2014 (E) 14 Table 1 gives recommended limits on the maximum penetrated thickness for different radiation sources. Some forms of insulation (e.g. highly absorbing) may lead to reduction in the limits on maximum penetrated thickness, wmax, given in Table 1. By agreement between the contracting parties, these values may be varied provided the position of the inner diameter edge can be measured with acceptable accuracy on the resulting radiograph/digital image using the methods described in 7.6 or 7.7. Table 1 — Maximum penetrated thickness range for different radiation sources for steel Radiation source Limits on maximum penetrated thickness wmax mm Basic (for generalized wall loss) Improved (for pitting flaws) X-ray (100 kV) ≤ 10 ≤ 7 X-ray (200 kV) ≤ 30 ≤ 20 X-ray (300 kV) ≤ 40 ≤ 30 X-ray (400 kV) ≤ 50 ≤ 35 Se 75 ≤ 55 ≤ 40 Ir 192 ≤ 80 ≤ 60 Co 60 ≤ 120 ≤ 85 For digital radiographs, somewhat higher values for the limits on maximum penetrated thickness than those given in Table 1 may be used. To determine the appropriate source(s) for a particular pipe, the maximum penetrated thickness, wmax, should be determined using Formula (1) and compared with the values given in Table 1. A graphical illustration of this procedure is given in Annex B. In cases where radiographs are produced using gamma rays, the total travel-time to position and rewind the source shall not exceed 10 % of the total exposure time. 6.3 Film systems and metal screens For radiographic examination, film system classes shall be used in accordance with EN ISO 11699-1. The radiographic film system class and metal screens to use with films for different radiation sources are given in Tables 2 and 3. See also EN ISO 17636-1:2013, Tables 2 and 3. When using metal screens, good contact between films and screens is required. This may be achieved either by using vacuum-packed films or by applying pressure. SIST EN 16407-1:2014
EN 16407-1:2014 (E) 15 Table 2 — Film system classes and metal screens for tangential radiography of steel, copper and nickel based alloy pipes Radiation source Film system class a Type and thickness of metal screens Class TA Class TB X-ray potentials ≤ 250 kV C 5 C 4 0,02 mm to 0,15 mm front and back screens of lead X-ray potentials > 250 kV to 500 kV C 5 C 4 0,1 mm to 0,2 mm front screens of lead b 0,02 mm to 0,2 mm back screens of lead X-ray potentials > 500 kV to 1 000 kV C 5 C 4 0,25 mm to 0,7 mm front and back screens of steel or copper c Se 75 Ir 192 C 6 C 5 0,02 mm to 0,2 mm front and back screens of lead b Co 60 C 6 C 5 0,25 mm to 0,7 mm front and back screens of steel or copper c X-ray equipment with energy from 1 MeV to 4 MeV C 6 C 5 0,25 mm to 0,7 mm front and back screens of steel or copper c X-ray equipment with energy above 4 MeV C 6 C 5 Up to 1 mm front screen of copper, steel or tantalum d Back screen of copper or steel up to 1 mm and tantalum up to 0,5 mm d a Better film system classes may also be used. b Ready packed films with a front screen up to 0,03 mm may be used if an additional lead screen of 0,1 mm is placed between the object and the film. c In class TA 0,5 mm to 2,0 mm screens of lead may also be used. d In class TA lead screens 0,5 mm to 1 mm may be used by agreement between the contracting p
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SLOVENSKI STANDARD
oSIST prEN 16407-1:2012
01-maj-2012
Neporušitveno preskušanje - Radiografski pregled korozije in nanosov v ceveh z
rentgenskimi in gama žarki - 1. del: Tangencialni radiografski pregled
Non-destructive testing - Radiographic inspection of corrosion and deposits in pipes by X
- and gamma rays - Part 1: Tangential radiographic inspection
Zerstörungsfreie Prüfung - Durchstrahlungsprüfung auf Korrosion und Ablagerungen in
Rohren mit Röntgen- und Gammastrahlen - Teil 1: Tangentielle Durchstrahlungsprüfung
Ta slovenski standard je istoveten z: prEN 16407-1
ICS:
19.100 Neporušitveno preskušanje Non-destructive testing
23.040.01 Deli cevovodov in cevovodi Pipeline components and
na splošno pipelines in general
oSIST prEN 16407-1:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 16407-1:2012
EUROPEAN STANDARD
DRAFT
prEN 16407-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2012
ICS
English Version
Non-destructive testing - Radiographic inspection of corrosion
and deposits in pipes by X- and gamma rays - Part 1: Tangential
radiographic inspection
Zerstörungsfreie Prüfung - Durchstrahlungsprüfung auf
Korrosion und Ablagerungen in Rohren mit Röntgen- und
Gammastrahlen - Teil 1: Tangentielle
Durchstrahlungsprüfung
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 138.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16407-1:2012: E
worldwide for CEN national Members.
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Contents Page
Foreword .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .6
4 Classification of radiographic techniques .7
5 General .8
5.1 Protection against ionizing radiation.8
5.2 Personnel qualification .8
5.3 Surface preparation .8
5.4 Identification of radiographs .8
5.5 Marking .8
5.6 Overlap of films or digital images .8
5.7 Types and positions of image quality indicators (IQI) .8
5.7.1 Single wire or step hole IQIs .8
5.7.2 Duplex wire IQI (digital radiographs) .9
6 Recommended techniques for making radiographs .9
6.1 Test arrangements .9
6.1.1 General .9
6.1.2 Radiation source located on the pipe centre line .9
6.1.3 Radiation source located offset from the pipe centre . 11
6.1.4 Alignment of beam and film/detector . 12
6.2 Choice of radiation source . 12
6.3 Film systems and metal screens. 13
6.4 Screens and shielding for imaging plates (computed radiography only) . 15
6.5 Reduction of scattered radiation . 16
6.5.1 Filters and collimators . 16
6.5.2 Interception of back scattered radiation . 17
6.6 Source-to-pipe centre distance . 17
6.7 Axial coverage and overlap . 18
6.8 Dimensional comparators . 18
6.9 Image saturation and use of lead strips to avoid burn-off . 20
6.10 Operation of computed radiography equipment . 20
7 Radiograph/digital image sensitivity, quality and evaluation . 21
7.1 Evaluation of image quality . 21
7.1.1 Maximum grey level in free beam (digital radiographs) . 21
7.1.2 Minimum normalised signal to noise ratio (digital radiographs) . 21
7.2 Density of film radiographs . 21
7.3 Film processing . 22
7.4 Film viewing conditions . 22
7.5 Dimensional calibration of radiographs or digital images . 22
7.5.1 Measurement of distances in radiographic setup . 23
7.5.2 Measurement of pipe outside diameter . 24
7.5.3 Dimensional comparator . 24
7.6 Wall thickness measurements for film radiographs . 24
7.7 Wall thickness measurements for digital radiographs . 24
7.7.1 Interactive on-screen measurements . 24
7.7.2 Grey-level profile analysis methods . 25
8 Digital image recording, storage, processing and viewing . 26
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8.1 Scan and read out of image. 26
8.2 Calibration of DDAs . 26
8.3 Bad pixel interpolation . 27
8.4 Image processing . 27
8.5 Digital image recording and storage . 27
8.6 Monitor viewing conditions . 27
9 Test report . 27
Annex A (normative) Determination of basic spatial resolution . 29
Annex B (informative) Choice of radiation source for different pipes . 33
Bibliography . 34
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Foreword
This document (prEN 16407-1:2012) has been prepared by Technical Committee CEN/TC 138 “Non-
destructive testing”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
prEN 16407 consists of the following parts, under the general title Non-destructive testing — Radiographic
inspection of corrosion and deposits in pipes by X- and gamma rays :
— Part 1: Tangential radiographic inspection;
— Part 2: Double Wall radiographic inspection.
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1 Scope
This part specifies fundamental techniques of film and digital radiography with the object of enabling
satisfactory and repeatable results to be obtained economically. The techniques are based on generally
recognized practice and fundamental theory of the subject.
This standard applies to the radiographic examination of pipes in metallic materials for service induced flaws
such as corrosion pitting, generalised corrosion and erosion. Besides its conventional meaning, "pipe" as used
in this standard should be understood to cover other cylindrical bodies such as tubes, penstocks, boiler drums
and pressure vessels.
Weld inspection for typical welding process induced flaws is not covered, but weld inspection is included for
corrosion/erosion type flaws.
The pipes may be insulated or not, and can be assessed where loss of material due, for example, to corrosion
or erosion is suspected either internally or externally.
This Part of this standard covers the tangential inspection technique for detection and through-wall sizing of
wall loss, including (a) with the source on the pipe centre line, and (b) with the source offset from it by the pipe
radius.
Part 2 of this standard covers double wall radiography, and note that the double wall double image technique
is often combined with tangential radiography with the source on the pipe centre line.
This standard applies to tangential radiographic inspection using industrial radiographic film techniques,
computed digital radiography (CR) and digital detector arrays (DDA).
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 12679:1999, Non-destructive testing — Determination of the size of industrial radiographic sources —
Radiographic method
EN 14784-1, Non-destructive testing — Industrial computed radiography with storage phosphor imaging
plates — Part 1: Classification of systems
EN 14096-2:2003, Non-destructive testing - Qualification of radiographic film digitisation systems - Part 2:
Minimum requirements
EN 25580:1992, Non-destructive testing - Industrial radiographic illuminators - Minimum requirements
prEN ISO 9712, Non-destructive testing — Qualification and certification of personnel
EN ISO 11699-1, Non-destructive testing - Industrial radiographic film - Part 1: Classification of film systems
for industrial radiography
EN ISO 11699-2, Non-destructive testing - Industrial radiographic film - Part 2: Control of film processing by
means of reference
FprEN ISO 17636–1:2012, Non-destructive testing of welds — Radiographic examination of welded joints —
Part 1: X- and gamma-ray techniques with film
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prEN ISO 19232–5:2011, Non-destructive testing — Image quality of radiographs — Part 5: Image quality
indicators (duplex wire type) - Determination of image unsharpness value
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
maximum penetrated thickness
w
max
maximum thickness of material for a pipe which occurs for a tangent to the inner pipe surface
3.2
nominal thickness
t
nominal thickness of the parent material only where manufacturing tolerances do not have to be taken into
account
3.3
object-to-detector distance
b
distance between the radiation side of the test object and the detector surface measured along the central
axis of the radiation beam
3.4
outside diameter
D
e
nominal outside diameter of the pipe
3.5
penetrated thickness
w
thickness of material in the direction of the radiation beam calculated on the basis of the nominal thickness
Note 1 to entry: For tangential radiographic inspection of a pipe, the minimum value for w is twice the pipe wall
thickness. For multiple wall techniques the penetrated thickness is calculated from the nominal thickness.
3.6
pipe centre to detector distance
PDD
distance between the pipe centre and the detector
3.7
source size
d
size of the radiation source
[SOURCE: EN 12679:1999, 2.1]
3.8
source-to-detector distance
SDD
distance between the source of radiation and the detector measured in the direction of the beam
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3.9
source-to-pipe centre distance
SPD
distance between the source of radiation and the pipe centre (pipe axis) measured in the direction of the beam
3.10
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
3.11
total effective penetrated thickness
W
tot
total equivalent thickness of metallic material in the direction of the radiation beam calculated on the basis of
the nominal thickness, with allowance for any liquid or gaseous product present in the pipe
3.12
actual wall thickness
WT
actual wall thickness of the pipe
3.13
measured wall thickness
WT’
measured wall thickness of the pipe on the radiograph or digital image
3.14
pixel size
geometrical centre-to-centre distance between adjacent pixels in a row (horizontal pitch) or column (vertical
pitch) of the scanned image
[SOURCE: EN 14096-2:2003]
4 Classification of radiographic techniques
The tangential radiographic techniques are divided into two classes:
basic technique TA
improved technique TB
The basic techniques, TA, are intended for tangential radiography of generalised wall loss, such as that due to
erosion or large scale corrosion.
The improved techniques, TB, should be used for the more demanding tangential radiography of localised
corrosion pitting flaws, which require higher sensitivity for detection and sizing.
Further technique improvements beyond TB are possible and may be agreed between the contracting parties
by specification of all appropriate test parameters.
The choice of radiographic technique shall be agreed between the concerned parties.
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5 General
5.1 Protection 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 legal
requirements must be applied. Local or national or international safety precautions when using
ionizing radiation shall be strictly applied.
5.2 Personnel qualification
Testing shall be carried out by proficient, suitably trained and qualified personnel and, where applicable, shall
be supervised by competent personnel nominated by the employer or, by delegation of the employer, the
inspection company in charge of testing. To demonstrate appropriate qualification it is recommended that
personnel be certified according to prEN ISO 9712 or an equivalent formalised system. Operating
authorisation for qualified person shall be issued by the employer in accordance with a written procedure.
NDT operations, unless otherwise agreed, shall be authorised by a competent and qualified NDT supervisory
individual (Level 3 or equivalent) approved by the employer.
The personnel shall prove additional training and qualification in digital industrial radiology if digital detectors
are being used.
5.3 Surface preparation
In general, surface preparation is not necessary, but where surface imperfections or coatings might cause
difficulty in detecting flaws or significant errors in thickness measurements, the surface shall be ground
smooth or the coatings shall be removed.
5.4 Identification of radiographs
Symbols shall be affixed to each section of the object being radiographed. The images of these symbols shall
appear in the radiograph outside the region of interest where possible and shall ensure unambiguous
identification of the section.
5.5 Marking
Permanent markings on the object to be examined shall be made in order to accurately locate the position of
each radiograph.
Where the nature of the material and/or its service conditions do not permit permanent marking, the location
may be recorded by means of accurate sketches.
5.6 Overlap of films or digital images
When radiographing an area with two or more films or separate detectors, the films or detectors shall overlap
sufficiently to ensure that the complete region of interest is radiographed. This shall be verified by a high
density marker on the surface of the object which will appear on each film or detector. If the radiographs will
be taken sequentially, the high density marker shall be visible on each of the radiographs.
5.7 Types and positions of image quality indicators (IQI)
5.7.1 Single wire or step hole IQIs
For tangential radiography, single wire or step hole IQIs are not applicable.
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5.7.2 Duplex wire IQI (digital radiographs)
If applicable, IQIs in accordance with prEN ISO 19232-5:2011 should be used for measurement of the basic
spatial resolution of the CR/DDA system (see 7.1.2 and Annex A). The duplex wire IQI shall be placed
adjacent to the imaging plate or detector array and positioned a few degrees tilted (2° – 5°) to the digital rows
or columns of the digital image.
6 Recommended techniques for making radiographs
6.1 Test arrangements
6.1.1 General
Normally radiographic techniques in accordance with 6.1.2 and 6.1.3 shall be used. For both techniques, the
film or digital detector shall be placed as close to the pipe as possible.
6.1.2 Radiation source located on the pipe centre line
For this arrangement the source is located in front of the pipe and with the film/detector at the opposite side,
as shown in Figure 1. The pipe can be non insulated (Figure 1a)) or insulated (Figure 1b)).
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a) non insulated pipe
b) insulated pipe
Key
1 film/detector
Figure 1 — Test arrangement and distances for tangential radiography with the source on the pipe
centre line
Note that the wall loss can be located on either the inner diameter or outer diameter surface of the pipe.
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6.1.3 Radiation source located offset from the pipe centre
For this arrangement, the radiation source is located in front of the pipe and with the film/detector at the
opposite side, as shown in Figure 2 a) (non insulated pipes) and Figure 2 b) (insulated pipes).
a) non insulated pipe
b) insulated pipe
Key
1 film/detector
Figure 2 — Test arrangement and distances for tangential radiography with the source offset from the
pipe centre line
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In this test arrangement, the source is offset from the pipe centre line, and is aligned with the centre of the
pipe wall, as shown in Figure 2. Note that the wall loss can be located on either the inner diameter or outer
diameter surface of the pipe.
6.1.4 Alignment of beam and film/detector
The beam of radiation shall be directed at the centre of the area being examined.
The film or detector should be aligned to be orthogonal to the centre of the radiation beam.
Modifications to these alignments and the test arrangements given in 6.1.2 and 6.1.3 may be needed in
special cases, due for example to the presence of obstructions.
Other ways of radiographing may be agreed between contracting parties.
6.2 Choice of radiation source
For tangential radiography, the choice of radiation source should be determined by the maximum penetrated
thickness of the pipe, w , which occurs for the path forming a tangent to the pipe inner diameter, as shown
max
in Figure 3.
Key
1 detector
Figure 3 — Maximum penetrated thickness, w , for the tangential technique
max
The maximum penetrated thickness, w , is given by:
max
w = 2 WT()D - WT (1)
max e
where
WT is the pipe wall thickness
D is the outside diameter of the pipe
e
Table 1 gives recommended limits on the maximum penetrated thickness for different radiation sources.
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Note that the presence of wall loss on the inner or outer diameters may cause the wall thickness, WT, to be
substantially less than the nominal value, t. This shall be taken into account when considering applicability of
radiation sources to inspection of degraded in-service pipes, according to Table 1.
By agreement between the contracting parties, these values may be varied provided the position of the inner
diameter edge can be measured with acceptable accuracy on the resulting radiograph/digital image using the
methods described in 7.6 or 7.7.
Table 1 — Maximum penetrated thickness range for different radiation sources for steel
Radiation source Limits on maximum penetrated thickness
w
max
mm
Basic Improved
(for generalised wall loss) (for pitting flaws)
X-ray (100 kV)
≤ 10 ≤ 7
X-ray (200 kV)
≤ 30 ≤ 20
X-ray (300 kV) ≤ 40 ≤ 30
X-ray (400 kV) ≤ 50 ≤ 35
Se 75
≤ 55 ≤ 40
Ir 192
≤ 80 ≤ 60
Co 60 ≤ 120 ≤ 85
For digital radiographs, somewhat higher values for the limits on maximum penetrated thickness than those
given in Table 1 may be used.
To determine the appropriate source(s) for a particular pipe, the maximum penetrated thickness, w , should
max
be determined using formula (1) and compared with the values given in Table 1. A graphical illustration of this
procedure is given in Annex B.
6.3 Film systems and metal screens
For radiographic examination, film system classes shall be used in accordance with EN ISO 11699-1.
The radiographic film system class and metal screens to use with films for different radiation sources are
given in Tables 2 and 3. See also Tables 2 and 3 of FprEN ISO 17636-1:2012.
When using metal screens, good contact between films and screens is required. This may be achieved either
by using vacuum-packed films or by applying pressure.
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Table 2 — Film system classes and metal screens for tangential radiography of steel, copper and
nickel based alloy pipes
a
Radiation source Type and thickness of metal
Film system class
screens
Class TA Class TB
X-ray potentials
0,02 mm to 0,15 mm front and back
C 5 C 4
≤ 250 kV
screens of lead
0,1 mm to 0,2 mm front screens of
b
X-ray potentials lead
C 5 C 4
> 250 kV to 500 kV
0,02 mm to 0,2 mm back screens of
lead
X-ray potentials
0,25 mm to 0,7 mm front and back
> 500 kV to C 5 C 4
c
screens of steel or copper
1 000 kV
Se 75 0,02 mm to 0,2 mm front and back
C 6 C 5
b
Ir 192 screens of lead
0,25 mm to 0,7 mm front and back
Co 60 C 6 C 5
c
screens of steel or copper
X-ray equipment
0,25 mm to 0,7 mm front and back
C 5
with energy from C 6
c
screens of steel or copper
1 MeV to 4 MeV
Up to 1 mm front screen of copper,
d
X-ray equipment
steel or tantalum
with energy above C 6 C 5
Back screen of copper or steel up to
4 MeV
d
1 mm and tantalum up to 0,5 mm
a
Better film system classes may also be used.
b
Ready packed films with a front screen up to 0,03 mm may be used if an additional lead
screen of 0,1 mm is placed between the object and the film.
c
In class A also 0,5 mm to 2,0 mm screens of lead may be used.
d
In class A lead screens 0,5 mm to 1 mm may be used by agreement between the
contracting parties.
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Table 3 — Film system classes and metal screens for tangential radiography of aluminium and
titanium pipes
a
Radiation source Film system class Type and thickness of
intensifying screens
Class TA Class TB
None or up to 0,03 mm front
X-ray potentials
and up to 0,15 mm back
≤ 150 kV
screens of lead
X-ray potentials 0,02 mm to 0,15 mm front and
> 150 kV to 250 kV back screens of lead
C 6 C 5
X-ray potentials 0,1 mm to 0,2 mm front and
> 250 kV to 500 kV back screens of lead
Se 75
0,02 mm to 0,2 mm front and
back screens of lead
Ir 192
a
Better film system classes may also be used.
Different film systems may be used by agreement of the contracting parties, provided the required optical
densities defined in 7.2 are achieved.
6.4 Screens and shielding for imaging plates (computed radiography only)
When using metal front screens, good contact between detectors and screens is required. This may be
achieved either by using vacuum-packed IPs or by applying pressure. Lead screens not in intimate contact
with the IPs may contribute to image unsharpness. The intensification obtained by use of lead screens in
contact with imaging plates is significantly smaller than in film radiography.
Many IPs are very sensitive to low energy back scatter and X-ray fluorescence of back shielding from lead.
Th
...
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