CEN ISO/TS 25393:2026

SLOVENSKI STANDARD
01-december-2026
Vezni elementi - Ocena sistema premazovanja - Dopolnilni in dodatni vidiki k CQI-
11 (ISO/TS 25393:2026)
Fasteners - Coating system assessment - Complementary and additional aspects to
CQI-11 (ISO/TS 25393:2026)
Verbindungselemente - Bewertung von Beschichtungssystemen - Ergänzende und
zusätzliche Aspekte zu CQI-11 (ISO/TS 25393:2026)
Fixations - Évaluation des systèmes de revêtement électrolytiques - Aspects
complémentaires et additionnels au CQI-11 (ISO/TS 25393:2026)
Ta slovenski standard je istoveten z: CEN ISO/TS 25393:2026
ICS:
21.060.01 Vezni elementi na splošno Fasteners in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN ISO/TS 25393
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
October 2026
TECHNISCHE SPEZIFIKATION
ICS 21.060.01
English Version
Fasteners - Coating system assessment - Complementary
and additional aspects to CQI-11 (ISO/TS 25393:2026)
Fixations - Évaluation des systèmes de revêtement Verbindungselemente - Bewertung von
électrolytiques - Aspects complémentaires et Beschichtungssystemen - Ergänzende und zusätzliche
additionnels au CQI-11 (ISO/TS 25393:2026) Aspekte zu CQI-11 (ISO/TS 25393:2026)
This Technical Specification (CEN/TS) was approved by CEN on 17 October 2026 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 25393:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (CEN ISO/TS 25393:2026) has been prepared by Technical Committee ISO/TC 2
"Fasteners" in collaboration with Technical Committee CEN/TC 185 “Fasteners” the secretariat of which
is held by BSI.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: 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, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO/TS 25393:2026 has been approved by CEN as CEN ISO/TS 25393:2026 without any
modification.
Technical
Specification
ISO/TS 25393
First edition
Fasteners — Coating system
2026-10
assessment — Complementary and
additional aspects to CQI-11
Fixations — Évaluation des systèmes de revêtement
électrolytiques — Aspects complémentaires et additionnels au
CQI-11
Reference number
ISO/TS 25393:2026(en) © ISO 2026

ISO/TS 25393:2026(en)
© ISO 2026
All rights reserved.
This ISO publication is protected by copyright and is owned by ISO and/or its licensors.
The content of this ISO publication is provided under licence, not sold. Use is subject to the applicable licence terms issued by ISO,
an ISO member body, or an authorized third-party distributor.
Except as required for implementation or expressly permitted by a separate licence, no part of this ISO publication may be
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Any use beyond the scope of the granted rights is prohibited and may result in legal action.
ISO copyright office
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO/TS 25393:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Application of CQI-11 to fasteners . 1
4.1 Applicability .1
4.2 Prevention of hydrogen embrittlement .2
5 Additional important items not dealt with in CQI-11, but in ISO 4042 and/or other
relevant technical specification(s) . 9
Annex A (informative) Chemical composition and coating thickness .10
Annex B (informative) Gaugeability and assemblability .12
Annex C (informative) Torque/clamp force testing. 14
Annex D (informative) Corrosion tests . 16
Bibliography .18

iii
ISO/TS 25393:2026(en)
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 2, Fasteners, Subcommittee SC 14, Surface
coatings, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 185, Fasteners, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
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.

iv
ISO/TS 25393:2026(en)
Introduction
rd
Plating system assessment (CQI-11) 3 edition was developed by AIAG (Automotive Industry Action Group)
with the intent to help better evaluation of the quality systems in place at plating shops supplying OEM
automotive coatings such as zinc and zinc alloy electrodeposits, decorative plating applied to metal or
plastic substrates, and hard chromium deposits, as well as electroless nickel and electropolishing processes.
The objective of the 3rd edition of CQI-11 was to update as needed, improve document clarity, and include
the ISO 9001 and IATF 16949:2016 Quality Management System concepts of “Process Approach” and “Risk
Management”.
The Automotive Industry Action Group (AIAG) was founded in 1982 by representatives of the three largest
North American automotive manufacturers: Ford, General Motors and Chrysler. It was originally created
to develop recommendations and a framework for the improvement of quality in the North-American
automotive industry. Among others, the AIAG publishes automotive industry standards, including
Production Part Approval Process (PPAP) quality specifications. These documents have become a de facto
quality standard in North America that have to be complied with by all Tier 1 suppliers. Increasingly, these
suppliers are now requiring complete compliance from their suppliers, so that many Tier 2 and 3 automotive
suppliers now shall also comply.
rd
CQI-11 is intended to be a self-Assessment auditing tool for electroplating processes, and its 3 edition
was published by AIAG in 2019; its goal is that “… all customer engineering design record and specification
requirements are properly understood by the supplier and that the process has the potential to produce product
consistently meeting these requirements during an actual production run at the quoted production rate." CQI-11
is used in the automotive supply chain to establish confidence in component suppliers and their production
processes.
However, CQI-11 remains a general system assessment for plating automotive parts. For the purpose of
fastener coating and in order to achieve the expected functional properties of the fasteners as specified in
ISO 4042, some specific modulus should also be considered additionally to CQI-11 and/or some “questions/
items” need to be completed.
The purpose of this document is to specifically address fastener-specific aspects not fully covered by CQI-11,
and to clarify some questions/items when its content is not applicable or not suitable for fasteners.
This document should be used as guidance by the electroplaters additionally to CQI-11, for the appropriate
application to fasteners.
This document is primarily established from the following basic documents:
— ISO 4042, Fasteners — Electroplated coating systems;
— ISO/TR 20491, Fasteners — Fundamentals of hydrogen embrittlement in steel fasteners;
— ISO 16047, Fasteners — Torque/clamp force testing.
It is consistent with ASTM F1941/F1941M and ASTM B633.

v
Technical Specification ISO/TS 25393:2026(en)
Fasteners — Coating system assessment — Complementary
and additional aspects to CQI-11
1 Scope
This document deals with electroplating process evaluation for fasteners, including fastener expected
coating properties.
This document is a complement to CQI-11 in order to deal with fastener specific aspects not fully covered by
CQI-11, and to clarify some questions/items when they are not fully suitable for fasteners.
This document is applicable to all parties involved in the supply chain for coated fasteners, i.e. fastener
manufacturers, chemical suppliers, electroplaters and purchasers.
The requirements for electroplating fasteners specified in this document are essentially based on ISO 4042,
ISO/TR 20491 and ISO 16047.
NOTE Requirements for electroplating fasteners are also given in ASTM F1941/F1941M.
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 1891-2, Fasteners — Terminology — Part 2: Vocabulary and definitions for coatings
ISO 4042:2022, Fasteners — Electroplated coating systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1891-2 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
rework
action to remove a coating system and to reprocess the targeted coating system
Note 1 to entry: The removal of the initially electrolytically applied coating is usually performed through a stripping
step, using an acid solution.
4 Application of CQI-11 to fasteners
4.1 Applicability
The applicability of CQI-11 requirements to fasteners are as specified in Table 1.

ISO/TS 25393:2026(en)
Table 1 — Key for Items/Questions in Table 2
AD ADditional item/question not included in CQI-11

SUB Item/question of CQI-11 applicable in principle, but SUBstituted as follows for the purpose of fasteners

NA Item/question of CQI-11 Not Applicable to fasteners, to be replaced by the appropriate question

4.2 Prevention of hydrogen embrittlement
Items specified in Table 2 shall be considered for fasteners.

ISO/TS 25393:2026(en)
Table 2 — Requirements related to the prevention of Internal Hydrogen Embrittlement (IHE)
CQI-11
Ref. No Item/Question IHE – Requirements for fasteners and comments, if any
(2019)
--- AD2.1 Measures related to internal hydrogen embrittlement ISO 4042:2022, 4.4
for steel fasteners (if any) shall be documented.
Only steel fasteners with a martensitic structure are concerned. For fasteners with a
bainitic structure, a written agreement between the supplier and the purchaser with
regard to IHE is necessary.
--- AD2.2 Baking process for fasteners (if any) shall be document- ISO 4042:2022, 4.4 and 4.5
ed.
Supplemental process verification (if any) shall be doc-
umented with regards to IHE.
Product testing (if any) shall be documented with
regards to IHE.
--- AD2.2.1 Steel fasteners with ISO metric external thread Extract of ISO 4042:2022
Table 3 — Measures related to IHE for fasteners in accordance with ISO 898 1
Property class <10.9 10.9 12.9/12.9
A B C
No supplemen- Supplemental Supplemental
tal process process process
verification or verification verification and/
product and/or product or product
testing with testing with testing with re-
regard to IHE regard to IHE gard to IHE
Measures related
AND OR AND
to IHE
No baking nec-
a, b
Baking Baking
essary
At the choice
— of the fastener —
manufacturer
See 4.4.3 and
See 4.4.2 See 4.4.4 and B.6
B.6
a
For alkaline zinc-nickel electroplatings with nickel content of
12 % to 16 %, the decision to not carry out baking shall be based on test-
ing (see B.6) and be agreed between the supplier and the purchaser.
b
For baking temperature and duration, see B.4.
--- AD2.2.2 Steel nuts Extract of ISO 4042:2022
Table 4 — Measures related to IHE for nuts in accordance with ISO 898-2

ISO/TS 25393:2026(en)
Table 2 (continued)
CQI-11
Ref. No Item/Question IHE – Requirements for fasteners and comments, if any
(2019)
Property class ≤12
A
No supplemental process verification
or product testing with regard to IHE
Measures related
to IHE AND
a, b
No baking necessary
See 4.4.2
a
Investigations have shown that tensile stress in critical areas of
nuts (including nuts with flange) is always lower than tensile stress in the
thread of the mating bolts, screws or studs with corresponding property
class (see measures related to IHE in Table 3); nuts in accordance with
ISO 898-2 (all property classes) always have a hardness less than 390 HV,
therefore baking is not necessary.
b
For all-metal prevailing torque nuts of property classes 10 and 12,
supplemental process verification or baking is required, at the choice of
the manufacturer.
For non-flat washers with hardness above 300 HV, a written agreement between the
supplier and the purchaser with regard to IHE is necessary.
--- AD2.2.3 Steel washers Extract of ISO 4042:2022
Table 5 — Measures related to IHE for flat washers in accordance with ISO 898-3
Property class ≤300 HV 380 HV
A B
No supplemental Supplemental process
process verifica- verification and/or product
tion testing with regard to IHE
or product testing
with regard to IHE
Measures related
AND OR
to IHE
b
No baking neces- Baking
a
sary
At the choice of the
—
fastener manufacturer
See 4.4.2 See 4.4.3
ISO/TS 25393:2026(en)
Table 2 (continued)
CQI-11
Ref. No Item/Question IHE – Requirements for fasteners and comments, if any
(2019)
a
When flat washers of property class 300 HV are to be used in
special applications (e.g. enlarged or slotted holes) where bending stress
may be present, baking may be necessary and shall be required by the
purchaser at the time of the order. For baking temperature and duration,
see B.4.
a
When flat washers of property class 380 HV are to be used in spe-
cial applications (e.g. enlarged or slotted holes) where bending stress may
be present, baking is necessary and shall be required by the purchaser at
the time of the order. For baking temperature and duration, see B.4.

--- AD2.2.4 Case hardened screws not designed for high clamp Extract of ISO 4042:2022
force
(e.g. tapping screws, thread-forming, self-drilling Table 6 — Measures related to IHE for case-hardened screws
screws, screws for soft materials such as plastic or typically not designed for high clamp force
wood, etc.)
Core >360 HV and
≤360 HV >390 HV
hardness ≤390 HV
Supplemental
Supplemental Supplemental
process
process pro
...