EN 12668-2:2010

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Zerstörungsfreie Prüfung - Charakterisierung und Verifizierung der Ultraschall-Prüfausrüstung - Teil 2: PrüfköpfeEssais non destructifs - Caractérisation et vérification de l'appareillage de contrôle par ultrasons - Partie 2: TraducteursNon-destructive testing - Characterization and verification of ultrasonic examination equipment - Part 2: Probes19.100Neporušitveno preskušanjeNon-destructive testingICS:Ta slovenski standard je istoveten z:EN 12668-2:2010SIST EN 12668-2:2011en,fr,de01-februar-2011SIST EN 12668-2:2011SLOVENSKI
STANDARDSIST EN 12668-2:2002/A1:2004SIST EN 12668-2:20021DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12668-2
February 2010 ICS 19.100 Supersedes EN 12668-2:2001English Version
Non-destructive testing - Characterization and verification of ultrasonic examination equipment - Part 2: Probes
Essais non destructifs - Caractérisation et vérification de l'appareillage de contrôle par ultrasons - Partie 2: Traducteurs
Zerstörungsfreie Prüfung - Charakterisierung und Verifizierung der Ultraschall-Prüfausrüstung - Teil 2: Prüfköpfe This European Standard was approved by CEN on 25 December 2009.
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 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 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.
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B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12668-2:2010: ESIST EN 12668-2:2011

Calculation of near field length of non-focusing probes . 45A.1 General. 45A.2 Straight beam probes . 45A.3 Angle beam probes . 46Annex B (informative)
Calibration block for angle-beam probes . 48Bibliography . 52 SIST EN 12668-2:2011

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.
near field length point on the acoustical axis where the acoustic pressure is at its maximum 3.3 horizontal plane of a sound beam plane perpendicular to the vertical plane of the sound beam including the acoustical axis in the material
1) Under preparation. SIST EN 12668-2:2011

fo
centre frequency arithmetic mean of upper and lower cut-off frequency 2olufff+= (1) NOTE In the frequency spectrum of an echo the upper and lower cut-off-frequencies are determined at -6 dB compared to the maximum amplitude.
3.5 peak-to-peak amplitude
h maximum deviation between the largest positive and the largest negative cycles of the pulse
NOTE See Figure 1. 3.6 probe data sheet sheet containing the information required by this standard NOTE The data sheet need not necessarily be a test certificate of performance. 3.7 pulse duration time interval over which the modulus of the unrectified pulse amplitude exceeds 10 % of its maximum amplitude, as shown in Figure 1 3.8 reference side reference side is the right side of an angle beam probe looking in the direction of the beam, unless otherwise specified by the manufacturer 3.9 relative bandwidth
∆∆∆∆frel ratio of the difference between the upper and lower cut-off frequencies fu and fl and the centre frequency fo
∆frel = [(fu - fl)/fo] × 100 % NOTE The relative bandwidth is expressed in percent (%). 3.10 squint angle for straight-beam probes
δδδδ deviation between the axis of the beam and a perpendicular to the coupling surface at the emission point
NOTE 1 See Figure 2. angle between the sides of the probe housing and the measured beam axis, projected onto the plane of the probe face
NOTE 2 See Figure 3. 3.11 vertical plane of a sound beam plane in which the sound beam axis in the probe wedge and the sound beam axis in the inspected component both lie SIST EN 12668-2:2011

8 Table 1 — List of information to be given in a data sheet
Category of probe
Contact Immersion
Straight beam Angle beam Straight Information Compressional Shear Compressional Shear Compressional to be given Single Double Single Single Double Single Double Single
non-f. focus. non-f. focus. non-f. non-f. focus. non-f. focus. non-f. focus. non-f. focus. non-f. focus. Manufacturer's name I I I I I I I I I I I I I I I Type of probe I I I I I I I I I I I I I I I Weight and size of probe I I I I I I I I I I I I I I I Type of connectors I I I I I I I I I I I I I I I TR connectors interchangeable?
I I
I I
I I
Material of transducers I I I I I I I I I I I I I I I Shape and size of transducers I I I I I I I I I I I I I I I Material of wedge, delay I I I I
I I I I I I I I
Material of wear plate I
Wear allowance I I I I
I I I I I I I I
I = Information; M = Measurement; C = Calculation. continued SIST EN 12668-2:2011

Category of probe
Contact Immersion
Straight beam Angle beam Straight Parameters to be Compressional Shear Compressional Shear Compressional measured or calculated Single Double Single Single Double Single Double Single
non-f. focus. non-f. focus. non-f. non-f. focus. non-f. focus. non-f. focus. non-f. focus. non-f. focus. Cross talk damping
M M
M M
M M
Pulse shape (time and frequency) M M M M M M M M M M M M M M M Centre frequency, band width M M M M M M M M M M M M M M M Pulse-echo sensitivity M M M M M M M M M M M M M M M Distance-amplitude curve M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C Impedance, static capacitance M M M M M M M M M M M M M M M I = Information; M = Measurement; C = Calculation; M,C = Measurement or calculation. continued SIST EN 12668-2:2011

10 Table 1 (end)
Category of probe
Contact Immersion
Straight beam Angle beam Straight Parameters to be Compressional Shear Compressional Shear Compressional measured or calculated Single Double Single Single Double Single Double Single
non-f. focus. non-f. focus. non-f. non-f. focus. non-f. focus. non-f. focus. non-f. focus. non-f. focus. Probe index
M M M M M M M M
Beam angle
M M M M M M M M
Angles of divergence M
M M
M
M
Beam axis offset M M M M M M M M M M M M M
Squint angle M M M M M M M M M M M M M
Focal distance, near field M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C M,C Focal width M M M M M M M M M M M M M M M Focal length M M M M M M M M M M M M M M M Physical aspects M M M M M M M M M M M M M M M I = Information; M = Measurement; C = Calculation; M,C = Measurement or calculation; Non-f. = Non-focusing. SIST EN 12668-2:2011

12 c) steel blocks with inclined faces with a notch as shown in Figure 5, and steel blocks with hemispherical holes as in Figure 6. Steel quality is as defined in EN ISO 7963. These blocks are used to measure the beam divergence in the vertical and horizontal plane respectively; d) an alternative steel block to measure index point, beam angle and beam divergence for angle beam probes is given in Annex B; e) ruler; f) feeler gauges starting at 0,05 mm. NOTE Not all blocks are required if only special kinds of probes are to be checked, e.g. blocks to measure the index point and beam angle are not necessary if only straight-beam probes have to be measured. For testing immersion probes the following reflectors and additional equipment shall be used: g) a steel ball or semi-spherical ended rod with smooth reflective surface. For each frequency range the diameter of ball or rod to be used is given in Table 2. Table 2 — Steel ball (rod) diameters for different frequencies Probe centre frequency MHz Diameter d of ball or rod mm 3 < f ≤ 15 d ≤ 3 0,5 ≤ f ≤3 3 < d ≤ 5 h) a large plane and flat reflector target. The target's lateral size shall be at least ten times wider than the diameter of the beam of the probe under test at the end of focal zone, as defined in 7.7.2.2. Thickness is at least five times the wavelength of the probe under test, calculated using the velocity of ultrasound in the material of the target. i) immersion tank equipped with a manual or automatic scanning bridge with five free axes:  three linear axes X, Y, Z;  two angular axes Θ and Ψ; j) automatic recording means: If the amplitudes of ultrasonic signals are recorded automatically, then it is the responsibility of the manufacturer to ensure that the system has sufficient accuracy. In particular, consideration shall be given to the effects of the system bandwidth, spatial resolution, data processing and data storage on the accuracy of the results. Typical set-ups to measure the sound beam of immersion probes are shown in Figures 15, 16 and 17. The scanning mechanism used with the immersion tank should be able to maintain alignment between the target and the probe in the X and Y directions, i.e. within ± 0,1 mm for 100 mm distance in the Z direction. The temperature of the water in the immersion tank shall be maintained at (20 ± 2) °C during the beam characterization of immersion transducers described in 7.7. Care shall be taken about the influence of sound attenuation in water, which, at high frequencies, causes a downshift of the echo frequency when using broadband probes. Table 3 shows the relation between frequency downshift and water path. SIST EN 12668-2:2011

mm MHz % 10 20 30 40 50 60 70 80 90 100 150 200 250 300 350 400 5 50 0 0 0 0 0 0 1 1 1 1 1 2 2 2 3 3
100 0 1 1 1 2 2 2 3 3 3 5 6 7 9 10 11 10 50 0 1 1 1 2 2 2 3 3 3 5 6 7 9 10 11
100 1 3 4 5 6 7 8 9 10 11 16 21 24 28 31 34 15 50 1 1 2 3 4 4 5 6 6 7 10 13 15 18 20 23
100 3 6 8 10 13 15 17 19 21 23 30 37 42 47 50 54 20 50 1 3 4 5 6 7 8 9 10 11 16 21 24 28 31 34
100 5 10 13 17 21 24 27 29 32 34 44 51 56 61 64 67 25 50 2 4 6 7 9 11 12 14 15 17 23 29 34 38 41 45
100 7 14 20 24 29 33 36 39 42 45 55 62 67 70 74 76 30 50 3 6 8 10 13 15 17 19 21 23 30 37 42 47 50 54
100 10 19 26 32 37 41 45 48 51 54 64 70 74 78 80 82 SIST EN 12668-2:2011

For broadband probes with a relative bandwidth exceeding 100 %, the lower frequency shall not be higher than %10l+fand the upper frequency shall not be lower than %10−uf. If the spectrum between fl and fu has more than one maximum, the amplitude difference between adjacent minima and maxima shall not exceed 3 dB. 7.4 Relative pulse-echo sensitivity 7.4.1 Method Relative pulse-echo sensitivity is defined as: ()aeVVS/log2010rel= (5) where Ve is the peak-to-peak voltage of the echo from a specified reflector, before amplification as measured in 7.2; Va is the peak-to-peak voltage applied to the probe with the ultrasonic instrument set to separate pulser/receiver mode. Probe sensitivity comparisons made with different types of ultrasonic instruments can vary, because the probe sensitivity is influenced by the coupling conditions and by the impedances of pulser, probe, cable and receiver. Therefore, these parameters have to be specified in the data sheet. 7.4.2 Acceptance criterion The relative pulse-echo sensitivity shall be within ± 3 dB of the manufacturer's specification. 7.5 Distance-amplitude curve 7.5.1 Method The amplitude of ultrasonic pulses varies with distance from the probe. Therefore, to evaluate echoes from reflectors, for all kinds of probes, distance-amplitude curves are needed using the reflectors in Table 4. SIST EN 12668-2:2011

Contact Immersion Disk-shaped reflectors Flat-bottom holes Flat-ended rod Cylindrical reflectors Side-drilled holes Cylindrical rod Spherical Hemispherical bottom hole Hemispherical ended rod or ball
Disk-shaped reflectors, side-drilled holes and hemispherical bottom holes are used as equivalent reflectors when using contact probes. With immersion probes, usually a small-sized steel ball is used to measure a distance-amplitude curve (see 7.7.2). For dual-element probes, the separation layer shall be perpendicular to the axis of the side-drilled holes. Using a series of reflectors of constant size but at different distances from the probe the received echo amplitudes are plotted against distance. At least eight measurement points on each curve shall be available. The distances used shall cover the focal range of focusing probes or the range including the near field length of non-focusing probes. Distances and amplitudes are determined on the calibrated screen of an ultrasonic instrument mentioned in the data sheet. To generate a noise curve, at each position of a maximized reflector echo the difference between noise and the reflector echo is determined by increasing the gain until the noise reaches the former height of the reflector echo. The noise level is measured with the probe removed from the object and the surface of the probe cleaned of couplant. If it is not possible to increase the gain by a sufficient amount, the difference between reflector echo amplitude and noise level can be estimated. If for example the reflector echo was at 40 % of full screen height, if the noise level is:  20 % then add 6 dB;  10 % then add 12 dB;  5 % then add 18 dB to the difference given by the attenuator readings. A diagram showing at least one distance-amplitude curve shall be available for each probe type, attached to the manufacturer's specification. This diagram shall also include a distance-noise curve. Figure 8 shows an example of different distance-amplitude curves, calculated for disk-shaped reflectors in steel (distance-gain-size diagram − DGS-diagram). Figure 9 shows an example of a measured distance-amplitude curve for 3 mm side-drilled holes. 7.5.2 Acceptance criterion Within the focal range the dB-difference between the noise level and the DAC shall not deviate by more than 3 dB from the difference given in the manufacturer's specification. SIST EN 12668-2:2011

7.6.1 Method For probes with an electrical matching circuit, e.g. induction coils in parallel or in series with the transducer, there is no frequency interval with constant impedance or phase. Therefore the complete impedance/phase curve is necessary to characterize these probes. For probes without electrical matching circuits the impedance is predominantly capacitive and this value can be determined from the network analyser. The impedance of the probe is determined with a network analyser or an impedance/gain/phase analyser as described in EN 12668-1. The probe shall be connected directly to the analyser with its fixed cable or, if the cable is removable, with a cable not longer than 100 mm.
An impedance modulus and phase curve shall be plotted against frequency within a band symmetrical about the centre frequency of the probe. 7.6.2 Acceptance criteria The measured modulus shall be within ± 20 % and the measured phase shall be within ± 5° of the manufacturer's specification. 7.7 Beam parameters for immersion probes 7.7.1 General The measurement technique consists of studying the probe acoustic beam in water, using a target. This target is a small, almost point source reflector, or a hydrophone receiver. The beam parameters are determined by scanning the reflector or hydrophone relative to the beam, either by moving the target or the probe. If the target is a reflector, echo-mode is used. Both transmitter and receiver characteristics of the probe are verified. If the target is a hydrophone, transmission mode is used, and then only the transmitting characteristics of the probe are verified. The same reflector or hydrophone shall be used for all the beam parameter measurements associated with one particular probe. Small variations in the measured position of maximum responses occur as measured by a hydrophone or different reflector types. Consequently, for reasons of repeatability, the equipment and the parameters of the target used shall be recorded with the results. Targets are listed in 6.1, f) and 6.2, g). Settings of the ultrasonic instrument or pulser receiver (pulse energy, damping, bandwidth, gain) shall be the same as those defined in 7.2. However, if the settings are changed during the measurement (gain for example), the new values shall be recorded on the result sheet. In the following paragraphs two methods are proposed for beam measurement. They differ only in the methods used to record the measurement results: a) direct measurement of specific beam parameters: the first technique, described in 7.7.2, is based on direct readings at specific points within the beam
(see Figures 10 to 14); b) measurements performed with an automated scanning system: SIST EN 12668-2:2011
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