SIST EN 12680-3:2012
(Main)Founding - Ultrasonic examination - Part 3: Spheroidal graphite cast iron castings
Founding - Ultrasonic examination - Part 3: Spheroidal graphite cast iron castings
This part of this standard specifies the requirements for the ultrasonic testing of steel castings for turbine components (with limited content of austenite) and the methods for determining internal discontinuities by the pulse echo technique. This part of this standard applies to the ultrasonic testing of steel castings which have usually received a grain refining treatment, and with wall thicknesses up to and including 600 mm.
Gießereiwesen - Ultraschallprüfung - Teil 3: Gussstücke aus Gusseisen mit Kugelgraphit
Diese Europäische Norm legt die Anforderungen fest an die Ultraschallprüfung von Gussstücken aus Gusseisen mit Kugelgraphit und die Techniken zur Bestimmung innerer Inhomogenitäten mit Hilfe der Impuls-Echo-Technik.
Diese Europäische Norm behandelt nicht die Ultraschallprüfung der Kugelgraphitausbildung bei Gusseisen mit Kugelgraphit.
Diese Europäische Norm behandelt nicht die Durchschallungstechnik.
ANMERKUNG Die Durchschallungstechnik hat keine ausreichende Empfindlichkeit zum Auffinden von Fehlern, die in Gussstücken aus Gusseisen mit Kugelgraphit vorkommen, und wird nur in Ausnahmefällen angewendet.
Fonderie - Contrôle par ultrasons - Partie 3: Pièces moulées en fonte à graphite sphéroidal
La présente Norme européenne spécifie les exigences relatives au contrôle par ultrasons des pièces moulées en fonte à graphite sphéroïdal, ainsi que les méthodes de détermination des discontinuités internes par la technique de contrôle par échos.
La présente Norme européenne ne s’applique pas au contrôle par ultrasons de la nodularité des fontes à graphite sphéroïdal.
La présente Norme européenne ne s’applique pas à la technique par transmission.
NOTE La technique par transmission n’a pas une sensibilité suffisante pour détecter les discontinuités présentes dans les pièces moulées en fonte à graphite sphéroïdal et n’est utilisée que dans des cas exceptionnels.
Livarstvo - Ultrazvočna preiskava - 3. del: Ulitki iz sive litine s kroglastim grafitom
Ta evropski standard določa zahteve za ultrazvočno preskušanje ulitkov iz sive litine s kroglastim grafitom in tehnike za ugotavljanje notranjih nezveznosti z impulzno-odmevno tehniko. Ta evropski standard ne velja za ultrazvočno preskušanje nodularnosti ulitkov iz sive litine s kroglastim grafitom. Ta evropski standard ne velja za tehniko prezvočenja.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Gießereiwesen - Ultraschallprüfung - Teil 3: Gussstücke aus Gusseisen mit KugelgraphitFonderie - Contrôle par ultrasons - Partie 3: Pièces moulées en fonte à graphite sphéroidalFounding - Ultrasonic examination - Part 3: Spheroidal graphite cast iron castings77.140.80Železni in jekleni ulitkiIron and steel castings77.040.20Neporušitveno preskušanje kovinNon-destructive testing of metalsICS:Ta slovenski standard je istoveten z:EN 12680-3:2011SIST EN 12680-3:2012en,fr,de01-januar-2012SIST EN 12680-3:2012SLOVENSKI
STANDARDSIST EN 12680-3:20031DGRPHãþD
SIST EN 12680-3:2012
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12680-3
November 2011 ICS 77.040.20 Supersedes EN 12680-3:2003English Version
Founding - Ultrasonic testing - Part 3: Spheroidal graphite cast iron castings
Fonderie - Contrôle par ultrasons - Partie 3: Pièces moulées en fonte à graphite sphéroïdal
Gießereiwesen - Ultraschallprüfung - Teil 3: Gussstücke aus Gusseisen mit Kugelgraphit This European Standard was approved by CEN on 15 October 2011.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12680-3:2011: ESIST EN 12680-3:2012
EN 12680-3:2011 (E) 2 Contents Page Foreword .31Scope .42Normative references .43Terms and definitions .44Requirements .54.1Order information .54.2Extent of testing .54.3Maximum permissible size of discontinuities .54.4Personnel qualification .54.5Wall section zones .55Testing .65.1Principles .65.2Material .65.3Equipment, coupling medium, time base range and sensitivity setting .65.4Preparation of casting surfaces for testing .95.5Test procedure .95.6Test report . 11Annex A (informative)
Significant technical changes between this European Standard and the previous edition . 21Bibliography . 22
SIST EN 12680-3:2012
EN 12680-3:2011 (E) 3 Foreword This document (EN 12680-3:2011) has been prepared by Technical Committee CEN/TC 190 “Foundry Technology”, 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 May 2012, and conflicting national standards shall be withdrawn at the latest by May 2012. 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. This document supersedes EN 12680-3:2003. Within its programme of work, Technical Committee CEN/TC 190 requested CEN/TC 190/WG 10 "Inner defects" to revise the following standard: EN 12680-3, Founding — Ultrasonic examination — Part 3: Spheroidal graphite cast iron castings. This is one of three European Standards for ultrasonic testing. The other standards are: EN 12680-1, Founding — Ultrasonic examination — Part 1: Steel castings for general purposes; EN 12680-2, Founding — Ultrasonic examination — Part 2: Steel castings for highly stressed components. Annex A provides details of significant technical changes between this European Standard and the previous edition. 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
SIST EN 12680-3:2012
EN 12680-3:2011 (E) 4 1 Scope This European Standard specifies the requirements for the ultrasonic testing of spheroidal graphite cast iron castings and the techniques for determining internal discontinuities by the pulse-echo technique. This European Standard does not apply to ultrasonic testing of the nodularity of spheroidal graphite cast irons. This European Standard does not apply to transmission technique. NOTE The transmission technique has insufficient sensitivity to detect the discontinuities found in spheroidal graphite cast iron castings and is used in exceptional cases only. 2 Normative references The following referenced documents are indispensable for the application 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. EN 473, Non-destructive testing — Qualification and certification of NDT personnel — General principles EN 583-1, Non-destructive testing — Ultrasonic examination — Part 1: General principles EN 583-2, Non-destructive testing — Ultrasonic examination — Part 2: Sensitivity and range setting EN 583-5, Non-destructive testing — Ultrasonic examination — Part 5: Characterization and sizing of discontinuities EN 1330-4, Non-destructive testing — Terminology — Part 4: Terms used in ultrasonic testing EN 12223, Non-destructive testing — Ultrasonic examination — Specification for calibration block No. 1 EN 12668-1, Non-destructive testing — Characterization and verification of ultrasonic examination equipment —Part 1: Instruments EN 12668-2, Non-destructive testing — Characterization and verification of ultrasonic examination equipment — Part 2: Probes EN 12668-3, Non-destructive testing — Characterization and verification of ultrasonic examination equipment — Part 3: Combined equipment EN ISO 7963, Non-destructive testing — Ultrasonic testing — Specification for calibration block No. 2 (ISO 7963:2006) 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 1330-4 and the following apply. 3.1 dross accumulation of fine slag particles (oxides, sulphides, etc.) in the rim zone of castings NOTE In smaller castings, dross is usually not detected by ultrasonic testing. SIST EN 12680-3:2012
EN 12680-3:2011 (E) 5 4 Requirements 4.1 Order information The following information shall be available at the time of enquiry and order (see also EN 583-1): the areas of the casting and the number or percentage of castings to which the ultrasonic testing require-ments apply; the severity levels for small castings in accordance with Table 1 and if applicable Table 3, or for large castings Table 2 and if applicable Table 4, to be applied to the various areas of the casting; requirements for a written test procedure. NOTE 1 Severity levels in Tables 1 and 3 as well as 2 and 4 can be chosen differently. NOTE 2 Small castings are typically produced under serial conditions, e.g. automatic moulding lines, with a mass up to 500 kg. NOTE 3 Large castings are typically hand moulded, with a mass higher than 500 kg. 4.2 Extent of testing The areas of the casting to be tested shall be agreed. This agreement shall state how these areas are to be tested, i.e. point testing or scanning, and in which directions. NOTE These areas should be preferably indicated on the casting drawing. For wall thicknesses outside of the range 10 mm to 500 mm, agreement shall be made between the parties concerned on the test procedure and also on the recording and acceptance levels. 4.3 Maximum permissible size of discontinuities Unless otherwise agreed between the parties concerned, the maximum permissible sizes of discontinuities shall not exceed those of the severity level given in either Table 1 resp. 2 and/or Table 3 resp. 4. 4.4 Personnel qualification Unless otherwise agreed, testing shall be performed by personal, qualified in accordance with EN 473 or by a certification scheme which is considered to be equivalent. 4.5 Wall section zones The wall section shall be divided into zones as shown in Figure 1. For wall thickness equal to or less than 10 mm the total wall thickness shall be considered as rim zone. Unless otherwise agreed these wall sections shall relate to the dimensions of the casting in the “as delivered” condition. When a discontinuity is located simultaneously in both, the rim zone and the core zone, the following applies: ≥ 50 % in the rim zone, the specified area of the largest discontinuity for the rim zone shall be doubled; < 50 % in the rim zone, the specified area of the largest discontinuity for the core zone shall be halved. SIST EN 12680-3:2012
EN 12680-3:2011 (E) 6 5 Testing 5.1 Principles The principles given in EN 583-1 and EN 583-2 shall apply. 5.2 Material The suitability of a material for ultrasonic testing is assessed by comparison with the echo height of a reference reflector (usually the first back-wall echo) and the noise signal. This assessment shall be carried out on selected casting areas which are representative of the surface finish and of the total thickness range. The assessment areas shall have parallel surfaces. The reference echo height shall be at least 6 dB above the noise level. If the echo height of this smallest detectable flat-bottomed or equivalent side-drilled hole diameter at the end of the test range to be assessed is less than 6 dB above the noise level, then the ultrasonic testability is reduced. In this case, the flat-bottomed or side-drilled hole diameter which can be detected with a signal-to-noise ratio of at least 6 dB shall be noted in the test report and the additional procedure shall be agreed between the manufacturer and the purchaser. NOTE If a distance-gain-size diagram (DGS) is available, the suitability of castings for ultrasonic testing with normal probes can be determined for example as follows: with the suppression switched off, the back-wall echo is brought to any reference level desired. The amplification according to the DGS diagram is then increased so that the echo signal height from the reference reflector according to 5.3.5.3 reaches the reference level. If the amplification is further increased by 6 dB the background noise level should not exceed the reference height. If necessary, a reference reflector can be used to determine the testing suitability in areas without the back-wall echo. 5.3 Equipment, coupling medium, time base range and sensitivity setting 5.3.1 Ultrasonic instrument The ultrasonic instrument shall meet the requirements given in EN 12668-1 and shall have the following characteristics: range setting, from at least 10 mm to 2 m continuously selectable, for longitudinal and transverse waves transmitted in steel; gain, adjustable in 2 dB maximum steps over a range of at least 80 dB with a measuring accuracy of 1 dB; time base and vertical linearities less than 5 % of the adjustment range of the screen; suitability at least for nominal frequencies from 0,5 MHz up to and including 5 MHz in pulse-echo technique with dual-element probe and single-element probe. 5.3.2 Probes and transducer frequencies The probes and transducer frequencies shall be as given in EN 12668-2 and EN 12668-3 with the following exceptions: to cover the range of discontinuity types to be detected, the casting can be tested using compression-wave dual-element probe or single-element probe. NOTE 1 Dual-element probe should be used for the testing of areas close to the test surface. SIST EN 12680-3:2012
EN 12680-3:2011 (E) 7 for special geometrical conditions, angle-beam probes can be used up to a sound path length of about 100 mm, preferably with nominal angles between 45° and 70°. The frequency value shall be selected to suit the test and shall be within the range 0,5 MHz to 5 MHz. Higher frequencies can be used for testing wall thicknesses of less than 20 mm or areas close to the surface. NOTE 2 For the detection of near-surface discontinuities, the use of dual-element and/or angle probes is recommended. NOTE 3 Since sound travels at different velocities in steel and spheroidal graphite cast iron, the actual angle of refraction deviates from the nominal angle of the probe for steel. If the sound velocity of spheroidal graphite cast iron is known, the angle of refraction of the probe can be determined from the sound velocity according to Figure 2. Figure 3 shows how the angle of refraction can be determined to an accuracy sufficient for practical purposes using two probes of the same type. The sound velocity of spheroidal graphite cast iron can also be determined from the angle of refraction α as follows: sccsinsin2553αα×=C (1) where Cc is the sound velocity of transverse waves in the casting in metres per second; 3 255 is the sound velocity of transverse waves for steel in metres per second, αc is the angle of refraction in the casting in degrees; αs is the angle of refraction in steel in degrees. NOTE 4 For special cases, longitudinal wave angle beam probes can be used. NOTE 5 The longitudinal wave velocity for spheroidal graphite cast iron is equal to or above 5 500 m/s. 5.3.3 Checking the ultrasonic testing equipment The ultrasonic testing equipment shall be checked regularly by the operator according to EN 12668-3. 5.3.4 Coupling medium A coupling medium in accordance with EN 583-1 shall be used. The coupling medium shall wet the test area to ensure satisfactory sound transmission. The same coupling medium shall be used for range and se
...
SLOVENSKI STANDARD
oSIST prEN 12680-3:2010
01-november-2010
/LYDUVWYR8OWUD]YRþQDSUHLVNDYDGHO 8OLWNLL]VLYHOLWLQHVNURJODVWLPJUDILWRP
Founding - Ultrasonic examination - Part 3: Spheroidal graphite cast iron castings
Gießereiwesen - Ultraschallprüfung - Teil 3: Gussstücke aus Gusseisen mit Kugelgraphit
Fonderie - Contrôle par ultrasons - Partie 3: Pièces moulées en fonte à graphite
sphéroidal
Ta slovenski standard je istoveten z: prEN 12680-3 rev
ICS:
77.040.20 Neporušitveno preskušanje Non-destructive testing of
kovin metals
77.140.80 Železni in jekleni ulitki Iron and steel castings
oSIST prEN 12680-3:2010 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 12680-3:2010
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oSIST prEN 12680-3:2010
EUROPEAN STANDARD
DRAFT
prEN 12680-3 rev
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2010
ICS 77.040.20 Will supersede EN 12680-3:2003
English Version
Founding - Ultrasonic examination - Part 3: Spheroidal graphite
cast iron castings
Fonderie - Contrôle par ultrasons - Partie 3: Pièces Gießereiwesen - Ultraschallprüfung - Teil 3: Gussstücke
moulées en fonte à graphite sphéroidal aus Gusseisen mit Kugelgraphit
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 190.
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 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 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
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12680-3 rev:2010: E
worldwide for CEN national Members.
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oSIST prEN 12680-3:2010
prEN 12680-3:2010 (E)
Contents
page
Foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Requirements . 5
4.1 Order information . 5
4.2 Extent of examination . 5
4.3 Maximum permissible size of discontinuities . 5
4.4 Personnel qualification . 5
4.5 Wall section zones . 5
5 Test method . 6
5.1 Principles . 6
5.2 Material . 6
5.3 Equipment, coupling medium, calibration and sensitivity . 6
5.4 Preparation of casting surfaces for examination . 8
5.5 Examination procedure . 8
5.6 Examination report . 11
Annex A (informative) Significant technical changes between this European standard and the
previous edition . 20
Bibliography . 21
2
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oSIST prEN 12680-3:2010
prEN 12680-3:2010 (E)
Foreword
This document (prEN 12680-3:2010) has been prepared by Technical Committee CEN/TC 190 “Foundry
Technology”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 12680-3:2003.
Within its programme of work, Technical Committee CEN/TC 190 requested CEN/TC 190/WG 4.10 "Inner defects"
to revise EN 12680-3:2003:
EN 12680-3, Founding — Ultrasonic examination — Part 3: Spheroidal graphite cast iron castings.
This is one of three European Standards for ultrasonic examination. The other standards are:
EN 12680-1, Founding — Ultrasonic examination — Part 1: Steel castings for general purposes.
EN 12680-2, Founding — Ultrasonic examination — Part 2: Steel castings for highly stressed components.
Annex A provides details of significant technical changes between this European Standard and the previous edi-
tion.
3
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oSIST prEN 12680-3:2010
prEN 12680-3:2010 (E)
1 Scope
This European Standard specifies the requirements for the ultrasonic examination of spheroidal graphite cast iron
castings and the methods for determining internal discontinuities by the pulse-echo technique.
This European Standard does not deal with the ultrasonic examination of the nodularity of spheroidal graphite cast
irons.
This European Standard does not cover the transmission technique.
NOTE The transmission technique has insufficient sensitivity to detect the discontinuities found in spheroidal graphite cast
iron castings and is used in exceptional cases only.
2 Normative references
The following referenced documents are indispensable for the application 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.
EN 583-1, Non-destructive testing — Ultrasonic examination — Part 1: General principles
EN 583-2, Non-destructive testing — Ultrasonic examination — Part 2: Sensitivity and range setting
EN 583-5, Non-destructive testing — Ultrasonic examination — Part 5: Characterization and sizing of disconti-
nuities
EN 1330-4, Non-destructive testing — Terminology — Part 4: Terms used in ultrasonic testing
EN 12223, Non-destructive testing — Ultrasonic examination — Specification for calibration block No. 1
EN 12668-1, Non-destructive testing — Characterization and verification of ultrasonic examination equipment —
Part 1: Instruments
EN 12668-2, Non-destructive testing — Characterization and verification of ultrasonic examination equipment —
Part 2: Probes
EN 12668-3, Non-destructive testing — Characterization and verification of ultrasonic examination equipment —
Part 3: Combined equipment
EN 27963, Welds in steel — Calibration block No. 2 for ultrasonic examination of welds (ISO 7963:1985)
3 Terms and definitions
For the purposes of this European Standard, the terms and definitions given in EN 1330-4 and the following apply.
3.1
dross
accumulation of fine slag particles (oxides, sulphides ….) in the rim zone of castings
NOTE In smaller castings dross is usually not detected by ultrasonic testing.
4
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oSIST prEN 12680-3:2010
prEN 12680-3:2010 (E)
4 Requirements
4.1 Order information
The following information shall be available at the time of enquiry and order (see also EN 583-1):
the areas of the casting and the number or percentage of castings to which the ultrasonic examination require-
ments apply;
the severity levels for small castings in accordance with Table 1 and if applicable Table 3, or for large castings
Table 2 and if applicable Table 4, to be applied to the various areas of the casting;
requirements for a written examination procedure.
NOTE 1 Severity levels in Tables 1 and 3 as well as 2 and 4 can be chosen differently.
NOTE 2 Small castings are typically produced under serial conditions, e.g. automatic moulding lines, with a mass up to 500
kg.
NOTE 3 Large castings are typically hand moulded, with a mass higher than 500 kg.
4.2 Extent of examination
The areas of the casting to be examined shall be agreed. This agreement shall state how these areas are to be
examined, i.e. point testing or scanning, and in which directions.
NOTE These areas should be preferably indicated on the casting drawing.
For wall thicknesses outside of the range 10 mm to 500 mm, agreement shall be made between the parties con-
cerned on the examination procedure and also on the recording and acceptance levels.
4.3 Maximum permissible size of discontinuities
Unless otherwise agreed between the parties concerned, the maximum permissible sizes of discontinuities shall
not exceed those of the severity level given in either Table 1 and/or Table 2.
4.4 Personnel qualification
Ultrasonic examination should be performed by qualified personnel according to EN 473 or equivalent.
4.5 Wall section zones
The wall section shall be divided into zones as shown in Figure 1. For wall thickness equal or less 10 mm the wall
thickness shall be considered as rim zone.
NOTE Unless otherwise agreed these wall sections shall relate to the dimensions of the casting in the “as delivered” condi-
tion.
When a discontinuity is located simultaneously in both, the rim zone and the core zone, the following applies:
≥ 50 % in the rim zone, the specified area of the largest discontinuity for the rim zone shall be doubled;
< 50 % in the rim zone, the specified area of the largest discontinuity for the core zone shall be halved.
5
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oSIST prEN 12680-3:2010
prEN 12680-3:2010 (E)
5 Test method
5.1 Principles
The principles given in EN 583-1 and EN 583-2 shall apply.
5.2 Material
The suitability of a material for ultrasonic examination is assessed by comparison with the echo height of a refer-
ence reflector (usually the first back wall echo) and the noise signal. This assessment shall be carried out on se-
lected casting areas which are representative of the surface finish and of the total thickness range. The assess-
ment areas shall have parallel surfaces.
The reference echo height shall be at least 6 dB above the noise signal. If the echo height of this smallest detect-
able flat-bottomed or equivalent side-drilled hole diameter at the end of the test range to be assessed is less than
6 dB above the grass level, then the ultrasonic testability is reduced. In this case, the flat-bottomed or side-drilled
hole diameter which can be detected with a signal-noise ratio of at least 6 dB shall be noted in the examination re-
port and the additional procedure shall be agreed between the manufacturer and the purchaser.
NOTE If a distance gain size diagram (DGS) is available, the suitability of castings for ultrasonic examination with normal
probes can be determined for example as follows: with the suppression switched off, the backwall echo is brought to any refer-
ence level desired. The amplification according to the DGS diagram is then increased so that the echo signal height from the
substitute reflector according to 5.3.5.3 reaches the reference level. If the amplification is further increased by 6 dB the back-
ground noise level should not exceed the reference height. If necessary, a reference reflector can be used to determine the test-
ing suitability in areas without the backwall echo.
5.3 Equipment, coupling medium, calibration and sensitivity
5.3.1 Ultrasonic instrument
The ultrasonic instrument shall meet the requirements given in EN 12668-1 and shall have the following character-
istics:
range setting, from at least 10 mm to 2 m continuously selectable, for longitudinal and transverse waves
transmitted in steel;
gain, adjustable in 2 dB maximum steps over a range of at least 80 dB with a measuring accuracy of 1 dB;
time-base and vertical linearities less than 5 % of the adjustment range of the screen;
suitability at least for nominal frequencies from 0,5 MHz up to and including 5 MHz in pulse-echo technique
with single-crystal and twin-crystal probes.
5.3.2 Probes and transducer frequencies
The probes and transducer frequencies shall be as given in EN 12668-2 and EN 12668-3 with the following excep-
tions:
to cover the range of discontinuity types to be detected, the casting can be examined using compression-wave
single-crystal or twin-crystal probes.
NOTE 1 Twin-crystal probes should be used for the examination of areas close to the test surface.
for special geometrical conditions, angle probes can be used up to a sound-beam path length of about
100 mm, preferably with nominal angles between 45° and 70°. The frequency value shall be selected to suit
the examination and shall be within the range 0,5 MHz to 5 MHz. Higher frequencies can be used for examin-
ing wall thicknesses of less than 20 mm or areas close to the surface.
NOTE 2 For the detection of near-surface discontinuities, the use of twin-crystal and/or angle probes is recommended.
6
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oSIST prEN 12680-3:2010
prEN 12680-3:2010 (E)
NOTE 3 Since sound travels at different velocities in steel and spheroidal graphite cast iron, the actual angle of refraction
deviates from the nominal angle of the probe for steel.
If the sound velocity of spheroidal graphite cast iron is known, the angle of refraction of the probe can be deter-
mined from the sound velocity according to Figure 2.
Figure 3 shows how the angle of refraction can be determined to an accuracy sufficient for practical purposes using
two probes of the same type. The sound velocity of spheroidal graphite cast iron can also be determined from the
angle of refraction α as follows:
sinα
c
C = 3 255× (1)
c
sinα
s
where
C the sound velocity in the casting in metres per second;
c
α is the angle of refraction in the casting in degrees;
c
α is the angle of refraction in steel in degrees.
s
NOTE 4 Typical sound velocity for spheroidal graphite cast iron is over 5500 m/s.
NOTE 5 To simplify examination, special probes can be used, e.g. angle probes for longitudinal waves.
5.3.3 Checking the ultrasonic examination equipment
The ultrasonic examination equipment shall be checked regularly by the operator according to EN 12668-3.
5.3.4 Coupling medium
A coupling medium in accordance with EN 583-1 shall be used. The coupling medium shall wet the examination
area to ensure satisfactory sound transmission. The same coupling medium shall be used for calibration and all
subsequent examination operations.
NOTE The sound transmission can be checked by ensuring one or more stable backwall echoes in areas with parallel sur-
faces
...
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