This document (prEN 10160:2025) has been prepared by Technical Committee CEN/TC 459/SC 1 “Test methods for steel (other than chemical analysis)”, the secretariat of which is held by AFNOR.

This document is currently submitted to the CEN Enquiry.

This document will supersede EN 10160:1999.

prEN 10160:2025 includes the following significant technical changes with respect to EN 10160:1999:

— The Scope was modified: thickness extended and new quality class added;

— Normative references updated;

— Definition 3.5 redrafted and a Note 1 to entry added;

— Clause 4 Items for agreement: added;

— Clause 6 – Procedure and Clause 13 – Operation procedure: more details and guidelines added;

— A new quality class S_A as an acceptance criteria in Tables 3 and 4 was added;

— Table 5 was added only for dual-transducer probes;

— Table 6 was added to give acceptance criteria for single-tranducer probes.

1.0 Scope

This document describes a method for the ultrasonic testing of uncoated flat steel product for internal discontinuities.

This document is applicable to flat product in nominal thickness range of 5 mm to 200 mm of non-alloyed or alloyed steel, excluding austenitic or austenoferritic steels. However, this document can be applied to the latter types of steels provided that the difference between the amplitude of the noise signal and that of the echo detection threshold is sufficient for the limit fixed.

This document also defines five quality classes for the flat product body (classes S₀, S₁, S_A, S₂ and S₃) and five classes (E₀, E₁, E₂, E₃, E₄) for the edges (see Clause 13).

Other methods of testing (e.g. by phased-array) or other test equipment may be used at the manufacturer's discretion provided that they give identical results to those obtained under the conditions of this document. In the event of a dispute, only the method defined in this document shall prevail.

Testing of flat product of thickness less than 5 mm or higher than 200 mm may be the subject of special agreements between the parties concerned.

The inspection is normally carried out in the place of production or on the premises of the supplier. If specified on the order, the inspection takes place in the presence of the purchaser or his representative^[1].

A list of equivalent terms in several European languages is given in Annex A.

2.0 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1330‑1, Non-destructive testing — Terminology – Part 1: List of general terms

EN 1330‑2, Non-destructive testing— Terminology — Part 2: Terms common to the non-destructive testing methods

EN ISO 5577, Non-destructive testing — Ultrasonic testing — Vocabulary (ISO 5577)

EN ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel (ISO 9712)

EN ISO 16810, Non-destructive testing — Ultrasonic testing — General principles (ISO 16810)

EN ISO 16811, Non-destructive testing — Ultrasonic testing — Sensitivity and range setting (ISO 16811)

EN ISO 16827, Non-destructive testing — Ultrasonic testing — Characterization and sizing of discontinuities (ISO 16827)

EN ISO 18563‑1, Non-destructive testing — Characterization and verification of ultrasonic phased array equipment — Part 1: Instruments (ISO 18563‑1)

EN ISO 18563‑2, Non-destructive testing — Characterization and verification of ultrasonic phased array equipment — Part 2: Array probes (ISO 18563‑2)

EN ISO 18563‑3, Non-destructive testing — Characterization and verification of ultrasonic phased array equipment — Part 3: Complete systems (ISO 18563‑3)

EN ISO 22232‑1, Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part 1: Instruments (ISO 22232‑1)

EN ISO 22232‑2, Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part 2: Probes (ISO 22232‑2)

EN ISO 22232‑3, Non-destructive testing — Characterization and verification of ultrasonic test equipment — Part 3: Combined equipment (ISO 22232‑3)

3.0 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 1330‑1, EN 1330‑2, EN ISO 5577 and the following apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp/

— IEC Electropedia: available at https://www.electropedia.org/

3.1

internal discontinuity

any imperfection lying within the thickness of the flat product, e.g planar or laminar imperfection, single-plane or multi-plane inclusion bands or clusters

Note 1 to entry: It is referred to in the text as discontinuity.

3.2

defect

unacceptable internal discontinuity, i.e. exceeding the specified maximum size or population density limits

3.3

population density

number of individual internal discontinuities of a size greater than a specified minimum size and less than a specified maximum size per specified area of body or length of edge zone

3.4

manual and assisted manual testing

testing by an operator applying an ultrasonic probe, or probes, to the flat product surface, manually executing the appropriate scanning pattern on the flat product surface and visually assessing ultrasonic signal indications on the ultrasonic instrument either by direct viewing or by built-in signal amplitude alarm devices

3.5

automated and semi-automated testing

testing using a mechanized means of applying the ultrasonic probe or probes to, and executing the appropriate scanning pattern on the flat product surface, together with ultrasonic signal indication evaluation by using fully automated software-based data acquisition

Note 1 to entry: Such testing shall be either fully automatic or semi-automatic when the operator performs basic equipment operation functions and validates testing results.

4.0 Items for agreements

The following aspects of ultrasonic testing may be agreed at the time of enquiry and order:

a) the manufacturing stage(s) at which ultrasonic testing shall be performed (see Clause 10);

b) the volume(s) to be tested and whether grid scanning coverage or complete scanning coverage is required (see Clause 13);

c) the Quality Class required, or the Quality Classes and the zones to which they apply (see Clause 15);

d) the applicable recording level and acceptance criteria if different from those detailed in Table 3, Table 4, Table 5 and Table 6;

e) whether any special scanning coverage, equipment or couplant is required in addition to that detailed in Clauses 8 and 13;

f) the techniques to evaluate discontinuities (see Clause 14);

g) the technique(s) to be used for setting sensitivity (see Clause 12);

h) whether the test is to be conducted in the presence of the purchaser or his representative;

i) whether a written procedure shall be submitted for approval by the purchaser (see Clause 6).

5.0 Principle

The method used shall be based on the reflection of ultrasonic waves, the beam axis of which is perpendicular to the surface of the product.

The examination shall consist of:

a) locating any discontinuity by comparing the amplitude of the discontinuity echo with the amplitude of the echo of a flat-bottomed hole of a given diameter and located at the same depth as the discontinuity (DAC, DGS, or equivalent methods);

NOTE Only those discontinuities giving an echo higher in amplitude to that of the echo obtained with the reference flat-bottomed hole are taken into consideration.

b) if applicable according to Clause 14, determining the contour of the discontinuity being defined by the positions of the centre of the probe corresponding to an echo amplitude of half the maximum amplitude of the discontinuity under consideration (6 dB drop method). The width of the discontinuity shall be determined perpendicular to the direction of rolling. The length shall be determined in the rolling direction.

The examination shall be carried out during the first ultrasonic scan for all the flat product thicknesses and from one side only.

6.0 Procedure

The testing shall be carried out in the place of production or on the premises of the supplier. If specified on the order, the testing may take place in the presence of the purchaser or his representative (see Clause 4 h)).

Ultrasonic testing shall be performed in accordance with a written procedure. Where specified in the enquiry or order, the written procedure shall be submitted to the purchaser for approval prior to testing.

This written procedure shall be in the form of:

— a product specification; or

— a procedure written specifically for the application; or

— this document may be used if it is accompanied by examination details specific to the application.

The procedure shall contain the following details as a minimum requirement:

a) description of the item to be examined;

b) reference documents;

c) qualification and certification of examination personnel;

d) stage of manufacture at which the examination is carried out;

e) examination zones specified in terms of the applicable Quality Classes;

f) any special preparation of scanning surfaces, if applicable;

g) couplant;

h) description of examination equipment;

i) setting;

j) scanning plan;

k) description and sequence of examination operations;

l) recording levels;

m) characterization of discontinuities;

n) acceptance criteria;

o) examination report.

7.0 Personnel

Testing shall be carried out by a qualified and certified personnel under the responsibility of a qualified and certified Level 3 personnel in accordance with EN ISO 9712.

8.0 Test equipment

8.1 Instrument

Instrument for manual testing shall feature A-scan presentation and shall comply with the requirements of EN ISO 22232‑1. or EN ISO 18563‑1, if applicable.

8.1.1 Probe

The probe used for testing shall comply with the requirements of EN ISO 22232‑2 or EN ISO 18563‑2.

The test equipment shall include at least one probe which may be either a probe with a single transducer serving for both emission and reception (single-transducer probe), a dual- transducer probe (separate emission-reception transducers) or multi-transducer probe (with several separated transducers). The beam axis of the waves emitted and received shall be perpendicular to the surface of the product.

The single-transducer probes shall be such that their dead zone is as small as possible, i.e. maximum 15 % of the flat product thickness or maximum 15 mm whichever is the smaller.

The focusing zone of the dual-transducer probes should be chosen or adapted to the thickness of the flat product.

The main dimensions of transducers are 10 mm to 35 mm in diameter and the probes shall have a nominal frequency in the range of 2 MHz to 5 MHz.

Probes of larger dimension and of a nominal frequency that is outside the range of 2 MHz to 5 MHz may be used for automatic or semi-automatic testing and/or when the flat product exhibits high attenuation provided that the main requirements of this document are met.

The type of the probe shall depend on the thickness of the flat product as given in Table 1:

Table 1 — Type of probe

Nominal thickness of the flat product (e) mm	Type of probe
_5 ≤_e_< 60	Dual-transducer probe
_60 ≤_e_≤ 200	Single or dual-transducer probe ^a),b)
^a) In the event of a dispute, the type of probe to be used shall be the subject of an agreement. ^b) Where automatic testing is carried out using immersion or water column techniques, single transducer probes < 60 mm thick may be used.

When dual-transducer probes are used, the orientation of the barrier separating the two transducers shall be perpendicular to the scanning direction.

8.1.2 Reference blocks or plates

The reference blocks or plates shall be made from a material with acoustic properties similar to those of the product to be tested. The surface condition of the reference block/plate shall be representative of that of the products to be tested. Unless otherwise specified, the reference block/plate shall contain at least two to five reflectors, covering the entire depth range to be tested (see Clause 12).

The reflecting surface of the flat-bottom hole shall be parallel to the test surface and free from pits or score marks that significantly degrade its ultrasonic reflectivity. The tolerance on the diameter of the flat-bottomed hole shall be ± 5 %.

8.1.3 Adjustment of the test equipment

Adjustment of the test equipment for use particularly shall require that the time base, power and amplification be determined.

The time base shall be adjusted to a value at which the distance, on the oscilloscope screen, between the transmitter pulse and back-wall echo is sufficient to allow a defect echo to be clearly detected between them.

The adjustment shall be carried out on the plate to be tested.

The power and amplification are adjusted in conjunction on a sound area which does not give any discontinuity echo. The first back-wall echo shall then be brought up to the maximum amplitude compatible with the height of the screen in the field of linearity of the test equipment (generally between 80 % and 100 % full screen height).

The system shall be checked on representative reference blocks/plates with flat bottom holes according to the concerned registration level (e.g. flat bottom hole 5 mm for dual-transducer probes) at least once every 8 working hours.

9.0 Coupling conditions

The coupling medium shall ensure an adequate contact between the probe and the surface of the flat product.

NOTE Water is normally used but other coupling media (e.g. oil, paste) can be used.

The same coupling medium shall be used for calibration, amplification adjustment, exploration and evaluation of discontinuities.

Once the examination has been carried out, the coupling medium shall be eliminated if its presence could have an adverse effect on further manufacturing or testing operations or on the integrity of the component.

10.0 Routine checking

The complete ultrasonic test equipment (instrument and probes) for manual testing shall be checked in accordance with the requirements of EN ISO 22232‑3 or EN ISO 18563‑3, or an internal manufacturer procedure.

11.0 Surface condition

Scanning surfaces shall be free from paint, non adhering scale, dry couplant, surface irregularities or any other substance, which could reduce coupling efficiency, hinder the free movement of the probe or cause errors in interpretation. The surface condition shall be considered acceptable providing the specified Quality Class can be achieved.

12.0 Scanning plan

12.1 General

The testing of the flat product body can be carried out partly according to 12.2 and/or 12.3, or 100 % (by agreement at the time of order).

12.1.1 Testing of the flat product body

12.1.2 Class S0, S1 and SA

Scanning shall comprise continuous testing along the lines of a grid made of a 200 mm square parallel to the edges of the flat product, or along parallel or oscillating lines distributed uniformly over the area, giving the same degree of control.

12.1.3 Class S2 and S3

Scanning shall comprise continuous testing along the lines of a grid made of a 100 mm square parallel to the edges of the flat product, or along parallel or oscillating lines distributed uniformly over the area, giving the same degree of control.

12.2 Testing of the flat product edges

Scanning shall comprise a full testing (100 %) of a zone in accordance with Table 2 over the four edges of the flat product.

Table 2 — Zone width for flat product edges

Thickness of the flat product (e) mm	Zone width mm
5 ≤ e < 50	50
50 ≤ e < 100	75
100 ≤ e ≤ 200	100

13.0 Procedure

13.1 Sensitivity and range setting

The requirements of sensitivity and range setting described below may not be applied for automatic testing equipment and shall be described in a specific manufacturer’s testing procedure in accordance with EN ISO 16811.

The general settings shall be determined in accordance with EN ISO 16810.

For each type of probe, curves shall be used giving:

a) the change in the amplitude of the back-wall echo as a function of the thickness of the flat product;

b) the change in the amplitude of the echo of the flat-bottomed hole as a function of its depth, for holes of diameter:

— 11 mm for classes S0, S1, SA, E0 and E1;

— 8 mm for classes S2, E2 and E3;

— 5 mm for classes S3 and E4.

When testing with a dual-transducer probe, only the 5 mm diameter hole shall be used for all the quality classes. The characteristic curves corresponding to the 8 mm and 11 mm diameter holes can coincide with the curve of the back-wall echo.

These curves shall be determined using reference blocks or plates (graduated block for the curve showing the variation in the amplitude of the back-wall echo and blocks comprising the flat-bottomed holes at different depths for the characteristic curves for 11 mm, 8 mm and 5 mm diameters). The reference blocks are made of carbon steel with a homogenous structure and each curve shall be determined from at least:

— two points distributed over the entire field of use of the probe for plate thicknesses up to 15 mm

— three points distributed over the entire field of use of the probe for plate thicknesses up to 20 mm

— four points distributed over the entire field of use of the probe for plate thicknesses up to 25 mm

— five points distributed over the entire field of use of the probe for plate thicknesses over 25 mm

All these curves may be supplied by the manufacturer of the probe (e.g. DGS-curve).

Thus, for a flat product of given thickness, the method consists of adjusting the amplitude of the back-wall echo to the value given by the curve for the variation of the back-wall echo amplitude and comparing the amplitude of the discontinuity echo with the characteristics curves (for 11 mm, 8 mm and 5 mm diameters) according to the class selected. Only discontinuities for which the amplitude of the echo is greater than that of the characteristic curve shall be taken into account.

13.1.1 Scanning speed

The scanning speed by manual testing shall not exceed 500 mm/s.

13.1.2 Determination of the area of discontinuities

13.1.3 Testing the flat product body

Testing with dual-transducer probes

The area of all the discontinuities giving responses that exceeded the characteristic curve shall be determined using the 6 dB drop method, i.e. the contour of the discontinuity being defined as the positions of the centre of the probe when the response from the discontinuity is equal to half the maximum amplitude in accordance with EN ISO 16827. A rectangle that encompasses the whole of the discontinuity is then determined., For the delimitation of the discontinuity, the probe is moved in all directions. The width is the dimension determined perpendicularly to the rolling direction, the length is the dimension determined in the rolling direction. The area of the rectangle is also calculated.

The area of the rectangle defines the area S of the discontinuity. Two nearby discontinuities shall be considered to represent a single discontinuity, the area being equal to the sum of the two if the distance between them is:

— less or equal to the length of the smallest of the two aligned discontinuities;

— less or equal to the width of the smallest of the two adjacent discontinuities.

When a flat product with a thickness ≥ 60 mm is tested with a dual transducer probe, for discontinuities whose echo amplitude is greater than that of the characteristic curve of the flat-bottomed hole with a diameter of 5 mm, its area can be determined using the 12 dB or 20 dB drop method in relation to the maximum level according to EN ISO 16827.

Testing with single transducer probes

The test shall consist of:

a) for class S₀, S₁ and S_A flat product: determination of the area in accordance with the method defined in 13.3.1.1;

b) for class S₂ and S₃ flat product: simply counting of the discontinuities which can be done when they are detected using the characteristic curves for 5 mm, 8 mm and 11 mm diameter holes.

The following is thus determined:

— for class S₂: the number of discontinuities giving echoes with an amplitude greater than the 11 mm diameter curve and the number N₂ of discontinuities (see Table 4) giving echoes with an amplitude between characteristic curves for the 8 mm and 11 mm diameter holes;

— for class S₃: the number of discontinuities giving echoes with an amplitude greater than the 8 mm diameter curve and the number N3 of discontinuities (see Table 4) giving echoes with an amplitude between characteristic curves for the 5 mm and 8 mm diameter holes.

13.1.4 Testing the edges

The test shall consist of scanning the total area of the edges, as specified in 8.3 (or areas to be welded according to sketches) where discontinuities were located under the same conditions as for flat product body (13.3.1).

The following are determined:

— the maximum dimension (L_max) and minimum dimension (L_min) of the discontinuity parallel to the rolling direction of the flat product;

— the area (S) of the discontinuity;

— the number of discontinuities smaller than the maximum area (S_max) or maximum length (L_max) and longer than minimum dimension (L_min) per 1 m length.

The determination of these properties of the discontinuity shall be obtained using the 6 dB drop method in relation to the maximum level in accordance with EN ISO 16827.

For a flat product with a thickness ≥ 60 mm controlled using a single transducer probe with classes E₃ or E₄, only the following shall be determined (see Table 6):

— for quality class E₃: the number of discontinuities giving echoes with an amplitude greater than the 11 mm diameter curve and the number N₂ of discontinuities (see Table 6) giving echoes with an amplitude between characteristic curves for the 8 mm and 11 mm diameter holes.

— for quality class E₄: the number of discontinuities giving echoes with an amplitude greater than the 8 mm diameter curve and the number N3 of discontinuities (see Table 6) giving echoes with an amplitude between characteristic curves for the 5 mm and 8 mm diameter holes.

14.0 Acceptance criteria

Table 3 and Table 4 give the acceptance criteria for the five quality classes (S₀, S₁, S_A, S₂, S₃) for the flat product body, depending on the type of probe used and Table 5 and Table 6 for the five edge classes (E₀, E₁, E₂, E₃, E₄) (see Figure 1).

Subject to agreement on ordering, the flat product may be supplied with different quality classes for flat product body and/or edges.

Table 3 — Acceptance criteria for testing with dual-transducer probes for the body of flat products for thicknesses < 60 mm

Quality Class	Unacceptable individual discontinuity mm²	Acceptable clusters of discontinuities
Quality Class	Unacceptable individual discontinuity mm²	Area^a considered mm²	Maximum density not greater than
S0	S > 5 000	1 000 < S ≤ 5 000	20 in the most populated 1 m x 1 m square
S1	S > 1 000	100 < S ≤ 1 000	15 in the most populated 1 m x 1 m square
SA	S > 500	100 < S ≤ 500	15 in the most populated 1 m x 1 m square
S2	S > 100	50 < S ≤ 100	10 in the most populated 1 m x 1 m square
S3	S > 50	20 < S ≤ 50	10 in the most populated 1 m x 1 m square
NOTE This table can be used for thicknesses 60 mm if an appropriate method other than the 6 dB method is used for the sizing of discontinuities (see 13.3.1.1). ^a) Dimensions of each discontinuity in the cluster in question (see 13.3.1.1).

Table 4 — Acceptance criteria for testing with single-transducer probes for the body of flat products

Quality Class	Unacceptable individual discontinuity mm²	Acceptable clusters of discontinuities
Quality Class	Unacceptable individual discontinuity mm²	Area^a or echo amplitude considered mm²	Maximum number in the most populated area per square meter
S₀	S > 5 000	1 000 < S ≤ 5 000	20 in the most populated 1 m x 1 m square
S₁	S > 1 000	100 < S ≤ 1 000	15 in the most populated 1 m x 1 m square
S_A	S > 500	100 < S ≤ 500	15 in the most populated 1 m x 1 m square
S2	Discontinuities where the flaw echo has an amplitude greater than the characteristic curve ø 11 mm	N2 (between ø 8 mm and ø 11 mm)	10 in the most populated 1 m x 1 m square
S3	Discontinuities where the flaw echo has an amplitude greater than the characteristic curve ø 8 mm	N3 (between ø 5 mm and ø 8 mm)	10 in the most populated 1 m x 1 msquare
^a) Dimensions of each discontinuity in the cluster in question (see 13.3.1.1).

Table 5 — Acceptance criteria with dual-transducer probes for the edge (or areas to be welded according to the sketches) of the flat product

Quality class	Recording level L_min mm	Acceptance criteria
		Permissible individual discontinuity size		*Maximum number of discontinuities per 1 m length smaller than the permissible individual discontinuity size (S_max and/or L_max) and longer than the recording level (L_min).*
		Maximum dimension L_max mm	Maximum Area S_max mm²
E0	50	100	2000	6
E1	25	50	1000	5
E2	20	40	500	4
E3	15	30	100	3
E4	10	20	50	2

Table 6 — Acceptance criteria with single-transducer probes for the edge (or areas to be welded according to the sketches) of the flat product

Quality class	Recording level L_min mm	Acceptance criteria
		Permissible individual discontinuity size		*Maximum number of discontinuities per 1 m length smaller than the permissible individual discontinuity size (S_max and/or L_max) and longer than the recording level (L_min).*
		Maximum dimension L_max mm	Maximum Area (S_max mm2) or maximum echo amplitude D
E0	50	100	2000	6
E1	25	50	1000	5
E2	20	40	500	4
E3	Discontinuities where the flaw echo has an amplitude greater than the characteristic curve ø 8 mm	N. A	D ≤ 11 mm	3
E4	Discontinuities where the flaw echo has an amplitude greater than the characteristic curve ø 5 mm	N. A	D ≤ 8 mm	2

Key

1	see Table 2 for the value of the edge zone width	5	edge zone
2	scan line	6	flat product
3	if d ≤ L₂ then S = S₁+S₂	7	width
4	principal rolling direction	8	length

Figure 1 — Schematic representation of terms used

15.0 Test report

The test report shall include at least the following information:

a) supplier name;

b) order information;

c) reference to this document, quality class and / or reference to an established procedure (e.g. specification);

d) reference data of the flat product examined (identification of the grade, heat treatment condition, surface condition, dimensions);

e) the characteristics of the ultrasonic probe (type, dimensions, frequency) and of the test equipment;

f) the operation conditions (e.g. coupling medium, scanning, method of area determination used, setting of the test equipment);

g) the test results related to the quality class stated in the order;

h) a list of special points which have been the subject of special agreement;

i) date of test report;

j) name and/or qualification of operator.

(informative)

List of equivalent terms in several European languages

Table A.1 — List of equivalent terms in several European languages

English	French	German	Italian	Dutch
Time base	Base de temps	Zeitablenkung	Base dei tempi	Tijdbasis
Noise	Bruit de fond	Rauschanzeige	Rumore di fondo	Ruis
Discontinuity echo	Écho d'anomalie	Fehlerecho	Eco del difetto	Indicatie-echo
Back echo	Écho de fond	Rückwandecho	Eco di fondo	Bodemecho
Probe	Traducteur	Prüfkopf	Sonda	Taster
Dual-transducer probe	Traducteur à émetteur et récepteur séparés	SE-Prüfkopf	Sonda ed emettitore e ricevitore separati (sonda doppia)	Dubbel-kristaltaster
Single probe	Traducteur à transducteur simple	Einschwinger- Prüfkopf	Sonda normale	Rechtetaster
Transducer	Transducteur	Schwinger	Transduttore	Kristal
Flat bottomed hole (FBH)	Trou à fond plat (TFP)	Flachbodenbohrung	Foro a fondo piatto	Vlakbodemgat
Dead zone	Zone morte	Tote Zone	Zona morta	Dode zone

Bibliography

[1] EN 10307, Non-destructive testing — Ultrasonic testing of austenitic and austenitic-ferritic stainless steels flat products of thickness equal to or greater than 6 mm (reflection method)

[2] ISO 17577, Steel — Ultrasonic testing of steel flat products of thickness equal or greater than 6 mm

In this case, all steps should be taken to ensure that the production process is not disturbed. ↑

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