ISO 11950:2026

International
Standard
ISO 11950
Third edition
Cold-reduced tinmill products —
2026-04
Electrolytic chromium/chromium
oxide-coated steel
Aciers pour emballage laminés à froid — Fer chromé
électrolytique
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General technical delivery condition . 4
5 Classification . 4
6 Information to be supplied by the purchaser . 4
6.1 Designation .4
6.2 Mandatory information .5
6.3 Options.5
7 Manufacturing features . 5
7.1 Manufacture.5
7.2 Annealing .5
7.3 Finish .6
7.4 Oiling .6
7.5 Imperfections .6
7.5.1 Coils .6
7.5.2 Sheets .7
8 Chromium/chromium in oxide coating mass . 7
9 Mechanical properties . 7
9.1 General .7
9.2 Hardness requirement . .7
9.3 Tensile property requirement .7
10 Tolerances on dimensions and shape . 8
10.1 General .8
10.2 Thickness and feather edge .8
10.2.1 Thickness .8
10.2.2 Feather edge .8
10.3 Width .8
10.4 Length .8
10.4.1 Length of coil .8
10.4.2 Length of sheet .8
10.5 Edge camber .8
10.6 Out-of-squareness of sheet .9
10.7 Flatness .10
10.7.1 Edge wave .10
10.7.2 Longitudinal and transverse bow .10
10.7.3 Centre fullness.10
11 Joint within a coil .11
11.1 General .11
11.2 Number of joints .11
11.3 Location of joints .11
11.4 Dimension of joints .11
11.4.1 Thickness .11
11.4.2 Overlap .11
12 Sampling .11
13 Test method .12
13.1 Chromium/chromium in oxide coating mass . 12
13.1.1 Test piece . 12
13.1.2 Method of determination . 12

iii
13.2 Hardness test . 12
13.2.1 Test piece . 12
13.2.2 Test method . 13
13.3 Tensile test . 13
13.3.1 Test piece . 13
13.3.2 Test method . 13
13.4 Flatness test . 13
13.4.1 General . 13
13.4.2 Edge wave .14
13.4.3 Longitudinal or transverse bow .14
13.4.4 Centre fullness.14
14 Retests .16
15 Inspection document .16
16 Dispatch and packaging .16
16.1 Coils .16
16.2 Sheets .17
16.3 Labelling .17
Annex A (normative) Hardness requirements for ECCS .18
Annex B (normative) Tensile property requirements for ECCS . 19
Annex C (informative) Steel types .21
Annex D (informative) Springback test for routine determination of R or R for ECCS .22
p0,2 eL
Annex E (normative) Methods for the determination of metallic chromium and chromium in
the oxides on the surface of electrolytic chromium/chromium oxide-coated steel .23
Annex F (normative) Rockwell HR15Tm values and their HR30Tm equivalents .30
Annex G (normative) Average chromium/chromium in oxide coating mass for the ECCS
produced through the trivalent chromium process .31
Bibliography .32

iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 9, Tinplate and
blackplate.
This third edition cancels and replaces the second edition (ISO 11949:2016), which has been technically
revised.
The main changes are as follows:
— an option to use either the trivalent chromium process or the hexavalent chromium process for
electrolytic chromium/chromium oxide-coated steel has been added (see 3.2);
— a new term entry has been added to define "fine stone finish" (see 3.8.3), and subsequent entries have
been renumbered;
— sheet numbers in bulk package other than multiples of 100 may be supplied (16.2);
— the maximum weight of sheets in bulk package has been increased up to 3 000 kg instead of 2 000 kg (see
16.2);
— several steel grades have been added (see Tables A.1, A.2 and B.1);
— the lower yield strength, R has been specified for CA (see 9.3, 13.3.2, Annex B and Annex D).
eL
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
International Standard ISO 11950:2026(en)
Cold-reduced tinmill products — Electrolytic chromium/
chromium oxide-coated steel
1 Scope
This document specifies requirements for single and double cold-reduced electrolytic chromium/chromium
oxide-coated steel (ECCS) in the form of sheets or coils.
Single cold-reduced ECCS is generally specified in nominal thicknesses that are multiples of 0,005 mm,
from 0,150 mm up to and including 0,600 mm. Double cold-reduced ECCS is generally specified in nominal
thicknesses that are multiples of 0,005 mm, from 0,100 mm up to and including 0,390 mm.
1)
This document applies to coils and sheets cut from coils in nominal minimum rolling widths of 600 mm.
2 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.
ISO 404, Steel and steel products — General technical delivery requirements
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 6892-1:2019, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 10474, Steel and steel products — Inspection documents
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
blackplate
cold-reduced low-carbon mild steel, applied for manufacturing ECCS
[1]
Note 1 to entry: See ISO 11951 .
3.2
electrolytic chromium/chromium oxide-coated steel
ECCS
cold-reduced low-carbon mild steel sheet or coil, electrolytically treated to produce on both surfaces a
duplex film of metallic chromium adjacent to the steel substrate with a top layer of hydrated chromium
oxide or hydroxide
Note 1 to entry: This can either be produced by a hexavalent chromium process or by a trivalent chromium process.
1) Nominal minimum rolling widths of 500 mm may be applied by agreement between the purchaser and the
manufacturer.
3.3
single cold-reduced
description of product in which the blackplate has been reduced to the desired thickness in a cold-reduction
mill and subsequently annealed and temper rolled
3.4
double cold-reduced
description of product in which the blackplate has had a second major reduction after annealing
3.5
standard grade ECCS sheet
product in sheet form which is confirmed to be suitable, under normal conditions of storage, for established
lacquering and printing over the entire sheet and is
a) free from surface imperfections which render the material unsuitable for the intended use, and
b) free from damage which render the material unsuitable for the intended use
Note 1 to entry: The standard material is defined as complying with the requirements as specified in this document.
3.6
batch annealing
box annealing
BA
process in which the cold-reduced strip is annealed in coil form, within a protective atmosphere, for a
predetermined time-temperature cycle
3.7
continuously annealing
CA
process in which cold-reduced coils are unwound and annealed in strip form within a protective atmosphere
3.8
finish
appearance of the surface of ECCS, governed by the surface roughness, R , of the steel base which results
a
from controlled preparation of the work rolls during the final stages of rolling
3.8.1
smooth finish
appearance of the blackplate resulting from the use of temper-mill work rolls that have been ground to a low
roughness
Note 1 to entry: This finish is used for the production of bright finish ECCS.
3.8.2
bright finish
appearance of the surface of ECCS using the smooth finish blackplate
3.8.3
fine stone finish
appearance of the surface of ECCS characterized by a directional pattern, resulting from the use of final-mill
work rolls that have been ground to a lower level of roughness than those used for stone finish
3.8.4
stone finish
appearance characterized by a directional pattern, resulting from the use of final-mill work rolls that have
been ground to a higher level of roughness than those used for the smooth finish
3.8.5
matt finish
appearance resulting from the use of temper-mill work rolls with dull surface textured by shot blast, electro
discharge texturing (EDT), electron beam texturing (EBT) or another suitable method

3.9
coil
rolled flat strip product which is wound into regularly superimposed laps so as to form a coil with almost
flat sides
3.10
longitudinal bow
line bow
residual curvature in the strip remaining along the direction of rolling
3.11
transverse bow
cross bow
mode of curvature in the sheet such that the distance between its edges parallel to the direction of rolling is
less than the sheet width
3.12
centre fullness
centre buckle
full centre
intermittent vertical displacement or wave in the strip occurring other than at the edges
Note 1 to entry: See Figure 8.
3.13
edge wave
intermittent vertical displacement occurring at the strip edge when the strip is laid on a flat surface
3.14
feather edge
transverse thickness profile
variation in thickness, characterized by a reduction in thickness close to the edges, at right angles to the
direction of rolling
3.15
edge camber
deviation of edge of coil/sheet from a straight line forming its chord
3.16
rolling width
measurement of the rolled strip perpendicular to the direction of rolling
3.17
stillage platform
base platform on which sheets are stacked to facilitate packing and ready transportation
3.18
consignment
quantity of material of the same specification made available for dispatch at the same time
3.19
bulk package
bulk
packaging unit comprising a stillage platform, the sheets and packaging material
3.20
line inspection
final inspection of the finished product performed by instruments and/or visual examination at normal
production-line speeds
4 General technical delivery condition
In cases where the technical delivery condition is not specified in this document, then ISO 404 shall apply.
5 Classification
Steel grades for this document are generally classified as non-alloy quality steels.
6 Information to be supplied by the purchaser
6.1 Designation
For the purposes of this document, ECCS is designated in terms of a steel grade classification based either
on the Rockwell HR30Tm hardness values or on the tensile properties. For the hardness requirements, the
steel grade designations shall be in accordance with Annex A, specifically Table A.1 for single cold-reduced
ECCS and in Table A.2 for double cold-reduced ECCS. For the tensile properties requirements, the steel grade
designations shall be in accordance with Table B.1 of Annex B.
ECCS covered by this document shall be designated by the following characteristics in the given sequence:
a) a reference to this document, i.e. ISO 11950;
b) the steel grade designation in accordance with Table A.1, Table A.2 or Table B.1;
c) the type of annealing used by the manufacturer (see 7.2);
d) the type of finish (see 7.3);
e) the dimensions, in millimetres:
— for coils, thickness × width;
— for sheets, thickness × width × length.
By agreement, the symbol “× C” after width may be designated for coils.
By agreement, the symbol “w” may be designated after the number for the width to indicate that the number
is the dimension perpendicular to the direction of rolling.
EXAMPLE
Single cold-reduced ECCS sheet, in accordance with this document, steel grade T61, continuously annealing (CA), stone
finish, with a thickness of 0,220 mm, a width of 800 mm and a length of 900 mm is designated:
ISO 11950-T61CA - stone - 0,220 × 800 × 900
Double cold-reduced ECCS coil, in accordance with this document, steel grade T75, continuously annealing (CA), stone
finish, with a thickness of 0,180 mm and a width of 750 mm is designated:
ISO 11950-T75CA - stone - 0,180 × 750
ECCS coil, in accordance with this document, steel grade TH415, continuously annealing (CA), stone finish (ST), with a
thickness of 0,200 mm, a width of 750 mm is designated:
ISO 11950- TH415 CA - ST - 0,200 × 750 × C
ECCS sheet, in accordance with this document, steel grade TS520, batch annealing (BA), stone finish, with a thickness
of 0,140 mm, a dimension perpendicular to the direction of rolling of 844 mm and a length of 755 mm is designated:
ISO 11950- TS520 BA - stone - 0,140 × 844w × 755

6.2 Mandatory information
The following information shall be given in the enquiry and order to assist the manufacturer in supplying
the correct material:
a) the designation as given in 6.1;
b) the quantity, expressed on an area or mass basis, e.g. 50 000 kg of sheets, 100 000 kg of coils;
c) the minimum and the maximum coil weight, the minimum and the maximum coil outer diameter, the
coil internal diameter, the core vertical or horizontal and the direction of winding (see 16.1);
d) the maximum weight of bulk package;
e) other inspection document than that specified by the manufacturer (see Clause 15);
f) end use;
g) any further special requirements.
NOTE Information on appropriate steel grade is suitable for shaping operations, such as stamping, drawing,
folding, beading and bending and assembly work such as joint forming, soldering and welding. The end use is important
when the steel grade is selected.
6.3 Options
At time of order, it may be agreed between the supplier and purchaser for the ECCS to be produced using
either hexavalent chromium process or chromium trivalent process.
In addition to the information in 6.2, the purchaser may wish to provide additional information to the
manufacturer to ensure that the order requirements are consistent with the end use of the product.
The purchaser shall inform the manufacturer of any modifications to the fabrication operations that will
significantly affect the way in which the ECCS is used.
NOTE When ordering cold-reduced ECCS, the purpose of manufacture for which the material is intended is
generally stated. When double cold-reduced ECCS is used for built-up can bodies, the rolling direction is around the
circumference of the can so as to minimize the hazard of flange cracking. In such cases, the direction of rolling is
clearly designated on the contract.
7 Manufacturing features
7.1 Manufacture
Continuously cast, fully-killed steel is applied except when otherwise specified. The examples of the steel
types of ECCS are shown in Annex C.
The steel type of ECCS shall be designed to secure food safety when ECCS is used for food application.
The purchasers should be aware of existing national regulations which may impose limitations on some
elements.
The manufacturing method of ECCS is left to the discretion of the manufacturer and is not specified in this
document.
7.2 Annealing
Annealing of ECCS shall be either batch annealing (BA) or continuous annealing (CA) and shall be specified
by the purchaser at the time of enquiry and order.

7.3 Finish
ECCS is usually available in the finishes as indicated in Table 1. The type of finish is designated either by the
ECCS finish or the code shown in Table 1.
Table 1 — Typical finishes for ECCS
Blackplate
b,c
Surface roughness
a
ECCS finish Code
Finish Ra
µm
Bright BT Smooth ≤0,35
Fine stone FS Fine stone 0,25 – 0,45
Stone ST Stone 0,35 – 0,60
Matt MM Matt ≥0,90
a
By agreement between the purchaser and the manufacturer, another code system
may be applied.
b
Values of surface roughness in this table are not mandatory. The values are given for
reference in order to classify the finishes.
c [2]
The measurement of surface roughness is in accordance with ISO 21920-3 .
NOTE 1 Special surface finishes are available by agreement at the time of ordering.
NOTE 2 Double cold-reduced ECCS is usually supplied with a stone finish.
7.4 Oiling
Under normal conditions of transport and storage, ECCS shall be suitable for surface treatments, such as
established lacquering and printing operations.
ECCS coils and sheets are supplied with an oil coating. The oil shall be one that is recognized (i.e. by the
relevant national or international authority) as being suitable for food packaging. Unless otherwise agreed
at the time of ordering, the kind of oil is at the discretion of the manufacturer.
NOTE For the oil, dioctyl sebacate (DOS) is usually used.
7.5 Imperfections
7.5.1 Coils
The manufacturer is expected to employ normal quality control and line inspection procedures to ensure
that the ECCS manufactured is in accordance with the requirements of this document.
However, the production of ECCS coils in continuous-strip mill operations does not afford the opportunity
for removal of all ECCS that do not conform with the requirements of this document.
At the time of shearing, sheets not conforming to the standard grade ECCS sheet shall be set aside by the
purchaser or its agent.
The quantity of sheets conforming with this document shall be at least 90 % of any one coil.
List items a) and b) in 3.5 cannot be verified by specific tests. Accordingly, those items are recommended to
be the subject of a special agreement between the purchaser and the manufacturer.
In processing ECCS coil, when the purchaser (or the purchaser's agent) encounters recurring imperfections
which seem to be excessive, it is essential, where practicable, that the processing of the coil is stopped and
the manufacturer is advised.
The purchaser is expected to have adequate handling, roller levelling and shearing equipment and inspection
facilities to segregate the sheets not conforming to the standard grade ECCS sheet and to take reasonable
care during these operations.
7.5.2 Sheets
Sheets shall not contain any imperfections as defined in 3.5.
8 Chromium/chromium in oxide coating mass
The minimum and maximum average values of coating mass of the samples selected in accordance with
Clause 12 shall be as given in Table 2, when tested as described in 13.1.
Table 2 — Average chromium/chromium in oxide coating mass
Average coating mass
on each surface
Form of chromium
mg/m
Minimum Maximum
Total chromium 50 185
Chromium in oxide 5 35
Average coating mass on each surface for the ECCS produced through the trivalent
chromium process shall refer to Annex G by agreement between the purchaser
and the manufacturer at the time of ordering.
9 Mechanical properties
9.1 General
For the purposes of this document, ECCS is classified into steel grades based on either Rockwell HR30Tm
hardness values or tensile properties. The purchaser shall indicate the specification either by hardness
requirement or by tensile properties requirement, but not for both, when ordering the material.
When ordering the material for applications such as drawn cans, DWI cans, twist off caps, etc., it is
recommended to indicate the specification according to the tensile property requirement.
Other mechanical properties might significantly influence the performance of ECCS in processing, and the
subsequent intended end use might vary depending on the steel type and the methods of casting, annealing
and temper rolling employed.
At the time of enquiry and order, it shall be agreed that properties of steel grade shall be verified either by
the hardness test or by the tensile test.
9.2 Hardness requirement
The hardness values for ECCS shall be as given in Table A.1 and Table A.2, Annex A when tested as described
in 13.2.
9.3 Tensile property requirement
The proof strength, R , for BA, or the lower yield strength, R , for CA shall be as given in Table B.1,
p0,2 eL
Annex B, when tested as described in 13.3.
For routine testing, R or R may be determined using the springback test as described in Annex D.
p0,2 eL
However, in cases of dispute, the method described in 13.3 shall be applied.

10 Tolerances on dimensions and shape
10.1 General
Tolerances on dimensions (i.e. thickness, width and length) and shape (i.e. edge camber, out-of-squareness
and flatness) are specified in 10.2 to 10.7, together with appropriate methods of measurement.
10.2 Thickness and feather edge
10.2.1 Thickness
Nominal thickness shall be a multiple of 0,005 mm. Nominal thickness other than multiple of 0,005 mm
may be specified by agreement between the purchaser and the manufacturer. Thickness out of the nominal
thickness range may be specified by agreement between the purchaser and the manufacturer.
5
The thickness of ECCS shall not deviate from the ordered nominal thickness by more than % at any point
8
except within 10 mm from the trimmed-edge.
The thickness shall be measured using a micrometer to an accuracy of 0,001 mm.
It is recommended that the micrometer should have a ball-ended shank and a curved-surface base anvil.
NOTE For routine internal quality control purposes, the thickness can also be determined in-line.
10.2.2 Feather edge
For both sheet and coil, the thickness when measured at a distance of 10 mm from the mill trimmed edge
shall not deviate from the actual centre thickness by more than −6 %.
10.3 Width
The width of ECCS shall be measured to the nearest 0,5 mm, at right angles to the direction of rolling.
For the products of this document which are delivered with trimmed-edge, the measured width shall not
3
deviate from the ordered width by more than mm.
0
10.4 Length
10.4.1 Length of coil
The difference between the actual length and the manufacturer’s indicated length, measured on any single
coil, shall not exceed by more than ±3 %, unless otherwise agreed.
10.4.2 Length of sheet
The length of sheet shall be measured to the nearest 0,5 mm. The measured length shall not deviate by more
than +3, −0 mm from the ordered length.
10.5 Edge camber
Edge camber is the maximum deviation (in the plane of the sheet) of an edge from a straight line forming a
chord to its extremities (see Figures 1 and 2).

The edge camber, E, expressed as a percentage of the chord length, is calculated using Formula (1):
D
E 100 (1)
L
where
D is the deviation from a straight line, in millimetres;
L is the length of chord, in millimetres.
For coils, the edge camber, measured over a distance (chord length) of 1 000 mm, shall not exceed 0,1 % (i.e.
1 mm).
Dimensions in millimetres
Key
W width
D deviation from a straight line
Figure 1 — Edge camber of coil
For sheets, the edge camber, measured over a chord length, shall not exceed 0,1 %.
Key
L length of chord
W width
D deviation from a straight line
Figure 2 — Edge camber of sheet
10.6 Out-of-squareness of sheet
Out-of-squareness is the deviation of an edge from a straight line drawn at a right angle to the other edge of
the sheet, touching one corner and extending to the opposite edge (see Figure 3).

The out-of-squareness, O , expressed as a percentage, is calculated using Formula (2):
s
A
O 100 (2)
s
B
where
A is the deviation;
B is the length or width of the sheet measured at a right angle to an edge.
For each sheet in the sample, the out-of-squareness shall not exceed 0,20 %. If the purchaser requires the
out-of-squareness to be less than 0,20 %, in the agreement between purchaser and manufacturer, the out-of-
squareness limit can be reduced to 0,15 %.
Key
A deviation
B length or width of the sheet measured at a right angle to an edge
Figure 3 — Out-of-squareness of sheet
10.7 Flatness
10.7.1 Edge wave
The height of edge wave, h , at any point shall not exceed 2,5 mm, when tested as described in 13.4.2. No
ew
more than six waves in excess of 1,5 mm shall be present over a cut length of 1 m for coil or proportional for
sheet.
10.7.2 Longitudinal and transverse bow
Bow may be either convex or concave face uppermost on the bulk package. The normal convention is to
express convex bow uppermost as a positive (+) value and concave bow as a negative (−) value.
The individual values of both longitudinal and transverse bow in levelled condition shall not exceed 30 mm,
when tested as described in 13.4.3. Where both convex and concave bow are present in the same coil, the
sum of the maximum values of each, ignoring the sign (±), shall not exceed 30 mm. In case of unlevelled
sheet from coil before cutting, the requirement of bow may be agreed between the purchaser and the
manufacturer.
10.7.3 Centre fullness
Centre fullness shall be determined by either the direct method as described in 13.4.4.1 or the indirect
method as described in 13.4.4.2. The selection of the method is at the discretion of the manufacturer. In case
of the direct method, the height of centre fullness, h , shall not exceed 5 mm when tested as described in
cf
13.4.4.1. In case of the indirect method, the height of centre fullness, h , shall not exceed 9 mm when tested
if
as described in 13.4.4.2.
NOTE Centre fullness is not clearly visible in a coil but usually becomes apparent during either printing or slitting.

11 Joint within a coil
11.1 General
The manufacturer shall ensure continuity of the coils within the limits of the lengths ordered, if necessary,
by means of electrically welded joints made after cold reduction. Requirements relating to the numbers,
locations and dimensions of the joints permitted within a coil are given in 11.2 to 11.4.
11.2 Number of joints
The number of joints in a coil shall not exceed three in lengths of 10 000 m.
11.3 Location of joints
The location of each joint in a coil shall be indicated clearly.
The location of each joint may be indicated, for example, by the insertion of a piece of non-rigid material and
punched holes. However, alternative methods may be agreed between the purchaser and the manufacturer
at the time of enquiry and order.
11.4 Dimension of joints
11.4.1 Thickness
The total thickness of any joints shall not exceed three times the nominal thickness of the material forming
the joints.
11.4.2 Overlap
In any lap joints, the total length of overlap shall not exceed 10 mm. The free overlap shall not exceed 5 mm
(see Figure 4).
Key
a total length of overlap
b free overlap
c direction of rolling
Figure 4 — Joint overlap
12 Sampling
For certifying the quality of product, the manufacturer shall take samples according to Figure 5 and carry
out test. One sheet for test specimen shall be taken for every 30 000 kg or less and remainder thereof of the
same properties, i.e. steel grade, dimensions and coating mass.

13 Test method
13.1 Chromium/chromium in oxide coating mass
13.1.1 Test piece
From each sheet selected in accordance with Clause 12, four discs shall be taken from each of the three sets
of positions marked X on Figure 5. The edge test pieces shall be taken not less than 25 mm from the edges of
the sheet. A test piece shall be a disc or a square having an area of approximately 2 500 mm . However, in the
case of the fluorescent X-ray spectrometric method, the irradiation area shall be 314 mm or over.
When applying the method described in Annex E, two of the four discs from each position shall be used for
separate determinations of the masses of chromium in the metallic chromium layer and the chromium oxide
layer on one surface of the sheet and the other t
...