🔩 Ultrasonic testing of steel plates and flat products from 6 mm — the echo method according to EN 10160
In short
A product standard: the testing of plates of non-alloy and alloy steel 6–200 mm thick for internal discontinuities, chiefly laminations. The test is performed according to PN-EN 10160:2001; Scope: uncoated steel flat products of nominal thickness 6–200 mm of non-alloy or alloy steel, excluding austenitic and austenitic-ferritic steels (these are permissible where the difference between the noise and the recording threshold is sufficient for the established limit); below 6 mm — separate agreements. The procedure comprises 10 steps; it is used for: Acceptance of heavy plates and other flat products of non-alloy and alloy steel 6–200 mm thick, Inspection of plates intended for tanks and welded structures — detection of laminations and bands of inclusions before cutting and welding, Testing of the edge zones of plates, including areas intended for welding (the standard permits the testing of areas to be welded according to sketches).
At a glance
- Standard: PN-EN 10160:2001
- Category: Materials and NDT
- Procedure steps: 10
- Scope: uncoated steel flat products of nominal thickness 6–200 mm of non-alloy or alloy steel, excluding austenitic and austenitic-ferritic steels (these are permissible where the difference between the noise and the recording threshold is sufficient for the established limit); below 6 mm — separate agreements
- Quality classes: body: S0, S1, S2, S3; edges: E0, E1, E2, E3, E4; by agreement the product may have different classes for the body and for the edges
- Reference holes: diameter 11 mm for S0, S1, E0, E1; 8 mm for S2, E2, E3; 5 mm for S3 and E4; diameter tolerance +5 %; with a twin-crystal probe, for all classes only the 5 mm hole
Overview
This is not a standard describing "how one tests with ultrasound" in general — it is a PRODUCT standard. It describes the method of ultrasonic testing of uncoated steel flat products for internal discontinuities and at the same time lays down the criteria by which the product is accepted or rejected. It applies to flat products of nominal thickness from 6 mm to 200 mm of non-alloy or alloy steel, excluding austenitic and austenitic-ferritic steels. The latter may be tested according to this standard on condition that the difference between the amplitude of the noise signal and the amplitude of the recording threshold is sufficient for the established limit. The testing of products thinner than 6 mm may be the subject of separate agreements between the parties.
The heart of the standard is the quality classes. The standard defines four quality classes for the body of the product — S0, S1, S2 and S3 — and five quality classes for the edges: E0, E1, E2, E3 and E4. The classes are not "a general level of care" but definite sets of three numbers: the non-permissible area of a single discontinuity, the range of areas taken into account for clusters, and the largest permissible number of such discontinuities in the most densely occupied square of 1 m × 1 m. The classes are selected in the order and — by agreement — the product may be supplied with different classes for the body and for the edges.
The class also affects the manner of testing. For classes S0 and S1 the scanning is carried out along the lines of a grid of 200 mm side parallel to the edge of the product, for classes S2 and S3 — along a grid of 100 mm side; instead of this, parallel or oscillating lines evenly distributed are permitted, giving the same degree of control. The edge zones, on the other hand, are tested over their whole extent, over a width depending on the thickness of the plate. The testing of the body is based on statistical methods, unless otherwise established in the order — by agreement one may order scanning with a defined coverage or scanning of the whole surface of the body.
The standard permits other methods of testing (for example transmission) or other apparatus at the discretion of the manufacturer, provided they give results identical with those obtained under the conditions of this standard. In the event of a dispute, only the method defined in this standard decides. The inspection is usually carried out at the place of production or at the supplier and, if so recorded in the order — in the presence of the purchaser or of their representative.
Status: in the PKN shop under the number PN-EN 10160 there is one item, PN-EN 10160:2001 in the Polish version, implementing EN 10160:1999, with no annotation about withdrawal — the standard is therefore still a current Polish Standard, even though the European edition dates from 1999. The normative references in the standard itself are correspondingly old (EN 473 instead of today's ISO 9712, prEN 1330-4 for ultrasonic terminology).
A revision of this standard is under way in CEN (the draft prEN 10160, enquiry stage) extending the scope to smaller thicknesses and adding a new quality class; until it is established, PN-EN 10160:2001 applies. We did not have the draft in hand — we do not describe its content here.
Method principle
The method is based on the reflection of ultrasonic waves, usually longitudinal, whose mean direction is perpendicular to the surface of the product. The testing consists of two steps. First the discontinuity is located by comparing the amplitude of its echo with the amplitude of the echo of a flat-bottomed hole of a given diameter, placed at the same depth as the discontinuity; only those discontinuities are taken into account whose echo has an amplitude at least equal to the echo from the reference hole. Then the area of the discontinuity is determined: its contour is defined by those positions of the centre of the probe which correspond to an echo amplitude equal to half the maximum amplitude of that discontinuity (the 6 dB method). The testing is carried out at the first pass of the probe, for all thicknesses of the product and from one side only. The diameter of the reference hole depends on the quality class: 11 mm for classes S0, S1, E0 and E1, 8 mm for classes S2, E2 and E3, 5 mm for classes S3 and E4. When testing with a twin-crystal probe, for all quality classes only the hole of 5 mm diameter is used, because the characteristic curves for the 8 mm and 11 mm holes merge with the curve of the backwall echo.
Applications
- Acceptance of heavy plates and other flat products of non-alloy and alloy steel 6–200 mm thick
- Inspection of plates intended for tanks and welded structures — detection of laminations and bands of inclusions before cutting and welding
- Testing of the edge zones of plates, including areas intended for welding (the standard permits the testing of areas to be welded according to sketches)
- Settling disputes about the internal quality of a flat product — in the event of a dispute only the method from this standard applies
- Establishing in the order the required quality class of the body and of the edges, also different for the body and for the edges
Key parameters
| Parameter | Value |
|---|---|
| Scope | uncoated steel flat products of nominal thickness 6–200 mm of non-alloy or alloy steel, excluding austenitic and austenitic-ferritic steels (these are permissible where the difference between the noise and the recording threshold is sufficient for the established limit); below 6 mm — separate agreements |
| Quality classes | body: S0, S1, S2, S3; edges: E0, E1, E2, E3, E4; by agreement the product may have different classes for the body and for the edges |
| Reference holes | diameter 11 mm for S0, S1, E0, E1; 8 mm for S2, E2, E3; 5 mm for S3 and E4; diameter tolerance +5 %; with a twin-crystal probe, for all classes only the 5 mm hole |
| Scanning grid of the body | classes S0 and S1 — continuous testing along the lines of a grid of 200 mm side parallel to the edge; classes S2 and S3 — a grid of 100 mm side; parallel or oscillating lines of the same degree of control are permissible |
| Width of the edge zone | 50 mm for thicknesses 6 ≤ e < 50 mm; 75 mm for 50 ≤ e < 100 mm; 100 mm for 100 ≤ e ≤ 200 mm — tested over their whole extent on four edges |
| Probes | diameter 10–25 mm, nominal frequency 2–5 MHz; twin-crystal probes for 6 ≤ e < 60 mm, single or twin-crystal for 60 ≤ e ≤ 200 mm; the dead zone of a single-crystal probe as small as possible — 15 % of the thickness of the product or 15 mm, whichever is the smaller |
Standard
- Standard number
- PN-EN 10160:2001
- Title (PL)
- Badanie ultradźwiękowe wyrobów stalowych płaskich grubości równej lub większej niż 6 mm (metoda echa)
- Title (EN)
- Ultrasonic testing of steel flat product of thickness equal or greater than 6 mm (reflection method)
Step-by-step procedure
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Establishing the quality classes and the testing plan
From the order read off the required quality class of the body (S0–S3) and of the edges (E0–E4). The testing of the body is based on statistical methods, unless otherwise established in the order; by agreement at the order one may provide for scanning with a defined coverage or for scanning of the whole body, with the conditions recorded in the agreement.
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Checking the condition of the surface and the coupling
The coupling medium is to ensure proper contact of the probe with the surface of the product. The condition of the surface must allow at least two successive backwall echoes to be distinguished when the probe is placed in an area free of internal discontinuities. Flat products are usually tested without any particular preparation of the surface.
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Selection of the probe
Select the type of probe according to Table 1 of the standard: for a nominal thickness of the product (or a depth of the discontinuity zone) of 6 ≤ e < 60 mm — a twin-crystal probe; for 60 ≤ e ≤ 200 mm — single or twin-crystal. The main dimensions of the probes are 10–25 mm diameter, nominal frequency 2–5 MHz; in automatic or semi-automatic testing, or with strong attenuation of the product, larger probes and frequencies outside this range are permissible, provided the essential requirements of the standard are met.
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Setting up the apparatus
Set the time base so that the distance on the screen between the transmission echo and the backwall echo allows a flaw echo between them to be clearly detected; at least two backwall echoes should be visible. Set the power and the gain together in an area free of discontinuities: bring the first backwall echo to the largest amplitude consistent with the height of the screen within the range of linearity of the instrument, usually 80–100 % of the screen height.
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Setting the sensitivity and the range on the curves
For each type of probe use the curves: of the variation of the backwall echo amplitude as a function of the thickness of the product, and of the variation of the amplitude of the echo of a flat-bottomed hole as a function of its depth — for the diameters 11 mm (classes S0, S1, E0, E1), 8 mm (S2, E2, E3) and 5 mm (S3, E4). For a product of a given thickness the backwall echo amplitude is brought to the value from the backwall echo curve, and the amplitude of the echo of a discontinuity is compared with the characteristic curve corresponding to the chosen class. Only discontinuities whose echo exceeds the characteristic curve are taken into account. The bottom of the hole is to be as flat as possible, parallel to the surface of introduction of the wave and free of pits and scratches impairing the reflection; diameter tolerance +5 %.
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Scanning the body
For classes S0 and S1 carry out continuous testing along the lines of a grid of 200 mm side parallel to the edge of the product; for classes S2 and S3 — along a grid of 100 mm side. Instead of this, parallel or oscillating lines evenly distributed over the surface are permissible, giving the same degree of control.
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Scanning the edge zones
Test over their whole extent the zone along all four edges of the product, of a width according to Table 2: 50 mm for thicknesses 6 ≤ e < 50 mm, 75 mm for 50 ≤ e < 100 mm, 100 mm for 100 ≤ e ≤ 200 mm. The whole surface of the zones is scanned (or of the areas provided for welding according to sketches), under the same conditions as the body.
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Determination of the area of a discontinuity by the 6 dB method
For discontinuities exceeding the characteristic curve, determine the contour as the positions of the centre of the probe at which the response is equal to half the maximum amplitude. Describe the discontinuity by a rectangle enclosing it entirely: the larger dimension is the length, the smaller — the width, and the area of the rectangle is the area S of the discontinuity. Two discontinuities close to each other are treated as one of an area equal to the sum of both, if the distance between them is less than or equal to the length of the smaller one. When testing with single-crystal probes in classes S2 and S3, instead of determining the area, the discontinuities are counted against the curves for the 5, 8 and 11 mm holes.
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Assessment according to the acceptance criteria
Apply Tables 3 and 4 for the body (depending on the type of probe used) and Table 5 for the edges. The values given below come from Table 3 (twin-crystal probes, thicknesses below 60 mm); the criteria of Table 4, which concern single-crystal probes, we DO NOT QUOTE here. For twin-crystal probes and thicknesses below 60 mm a single discontinuity is not permissible when: S > 5000 mm² (S0), S > 1000 mm² (S1), S > 100 mm² (S2), S > 50 mm² (S3). Clusters are assessed in the most densely occupied square of 1 m × 1 m: for S0 not more than 20 discontinuities of area 1000 < S < 5000 mm², for S1 not more than 15 of area 100 < S < 1000 mm², for S2 not more than 10 of area 50 < S < 100 mm², for S3 not more than 10 of area 20 < S < 50 mm². For the edge zones (Table 5) the permissible dimensions and numbers per 1 m of length are: E0 — Lmax 100 mm, Smax 2000 mm², Lmin 50 mm, 6 items; E1 — 50 mm, 1000 mm², 25 mm, 5 items; E2 — 40 mm, 500 mm², 20 mm, 4 items; E3 — 30 mm, 100 mm², 15 mm, 3 items; E4 — 20 mm, 50 mm², 10 mm, 2 items.
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Test report
On request the manufacturer presents a report containing at least: a reference to this European Standard; the data of the product (grade, condition of heat treatment, condition of the surface, dimensions); the characteristics of the probe (type, dimensions, frequency) and of the apparatus; the conditions of performance (couplant, scanning, the method used for determining the area, the setting-up of the apparatus); the results of the testing; a list of the particular points which are the subject of separate agreements; the date of the report.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Ultrasonic flaw detector with an amplifier calibrated in decibels | with a screen allowing the path of the waves in the product to be followed, with distinct and sharp echoes, with control of the gain, of the power and of the time base; instruments without a monitor are also permissible if they carry out an automatic measurement and assessment of the amplitude and their measuring unit is calibrated in dB | — |
| Twin-crystal probe (separate transmitter and receiver) | required for thicknesses 6 ≤ e < 60 mm; the separating partition between the transducers set perpendicular to the direction of scanning; the focal zone matched to the thickness of the product | — |
| Single-crystal probe | permissible for 60 ≤ e ≤ 200 mm (in the event of a dispute the type of probe is agreed between the parties); in automatic testing with the immersion technique or with a water jet, single-transducer probes are permissible below 60 mm as well | — |
| Reference blocks with flat-bottomed holes of 11 mm, 8 mm and 5 mm and a step block | of carbon steel of homogeneous structure; the step block for the curve of the variation of the backwall echo amplitude, the blocks with holes at various depths for the characteristic curves; each curve determined from at least five points over the whole field of application of the probe — the curves may be supplied by the manufacturer of the probe | — |
| Probe guiding system | the probe held by hand or mounted in equipment for continuous testing with a scanning speed small enough for the discontinuities to be easily located, allowing for the delay of the image on the screen, or fitted with a discontinuity alarm | — |
| Coupling medium | usually water; at the discretion of the supplier other media are permissible, for example oil or paste | — |
Health and safety (OHS)
- The testing is carried out by qualified personnel under the responsibility of a person certified to level 3 in accordance with EN 473 (the standard refers to EN 473; today the qualification and certification of NDT personnel is carried out according to ISO 9712).
- The checking of the apparatus is carried out in accordance with the appropriate national standards, and the setting-up of the measuring system is checked at least once every 8 hours — omitting this check invalidates the results from the whole shift (this is our conclusion from the requirement of the standard and not its literal wording).
- The method is safe for the operator (no ionising radiation), but it is usually carried out in the production department or at the supplier — the rules of safety of the operation of the plant apply there, including in the moving of heavy plates.
- When testing with water coupling and with immersion techniques one must reckon with electrical hazards and with a slippery surface of the working place.
- If the testing is to take place in the presence of the purchaser or of their representative, every step is to be taken so as not to disturb the production process.
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN 10160:2001 — “Ultrasonic testing of steel flat product of thickness equal or greater than 6 mm (reflection method)”.
How does this method work?
The method is based on the reflection of ultrasonic waves, usually longitudinal, whose mean direction is perpendicular to the surface of the product. The testing consists of two steps.
What is the measuring range and accuracy?
Scope: uncoated steel flat products of nominal thickness 6–200 mm of non-alloy or alloy steel, excluding austenitic and austenitic-ferritic steels (these are permissible where the difference between the noise and the recording threshold is sufficient for the established limit); below 6 mm — separate agreements; Quality classes: body: S0, S1, S2, S3; edges: E0, E1, E2, E3, E4; by agreement the product may have different classes for the body and for the edges; Reference holes: diameter 11 mm for S0, S1, E0, E1; 8 mm for S2, E2, E3; 5 mm for S3 and E4; diameter tolerance +5 %; with a twin-crystal probe, for all classes only the 5 mm hole; Scanning grid of the body: classes S0 and S1 — continuous testing along the lines of a grid of 200 mm side parallel to the edge; classes S2 and S3 — a grid of 100 mm side; parallel or oscillating lines of the same degree of control are permissible.
How long does the test take?
The procedure comprises 10 steps. The standard does not give a duration for every stage — the laboratory's own procedure decides.
What equipment is required?
Ultrasonic flaw detector with an amplifier calibrated in decibels, Twin-crystal probe (separate transmitter and receiver), Single-crystal probe, Reference blocks with flat-bottomed holes of 11 mm, 8 mm and 5 mm and a step block, Probe guiding system, Coupling medium.
Where is this test used?
Acceptance of heavy plates and other flat products of non-alloy and alloy steel 6–200 mm thick; Inspection of plates intended for tanks and welded structures — detection of laminations and bands of inclusions before cutting and welding; Testing of the edge zones of plates, including areas intended for welding (the standard permits the testing of areas to be welded according to sketches); Settling disputes about the internal quality of a flat product — in the event of a dispute only the method from this standard applies; Establishing in the order the required quality class of the body and of the edges, also different for the body and for the edges.
What safety precautions apply?
The testing is carried out by qualified personnel under the responsibility of a person certified to level 3 in accordance with EN 473 (the standard refers to EN 473; today the qualification and certification of NDT personnel is carried out according to ISO 9712).; The checking of the apparatus is carried out in accordance with the appropriate national standards, and the setting-up of the measuring system is checked at least once every 8 hours — omitting this check invalidates the results from the whole shift (this is our conclusion from the requirement of the standard and not its literal wording).; The method is safe for the operator (no ionising radiation), but it is usually carried out in the production department or at the supplier — the rules of safety of the operation of the plant apply there, including in the moving of heavy plates.; When testing with water coupling and with immersion techniques one must reckon with electrical hazards and with a slippery surface of the working place.; If the testing is to take place in the presence of the purchaser or of their representative, every step is to be taken so as not to disturb the production process.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN 10160.