prEN ISO 22479

SLOVENSKI STANDARD
01-marec-2026
Korozija kovin in zlitin - Korozijski preskus z žveplovim dioksidom (SO2) v vlažni
atmosferi (metoda s stalno (fiksno) koncentracijo plina) (ISO/DIS 22479:2026)
Corrosion of metals and alloys - Sulfur dioxide test in a humid atmosphere (fixed gas
method) (ISO/DIS 22479:2026)
Korrosion von Metallen und Legierungen - Prüfung mit Schwefeldioxid in feuchter
Atmosphäre (Verfahren mit festem Gasvolumen) (ISO/DIS 22479:2026)
Corrosion des métaux et alliages - Essai au dioxyde de soufre en atmosphère humide
(méthode avec volume fixe de gaz) (ISO/DIS 22479:2026)
Ta slovenski standard je istoveten z: prEN ISO 22479
ICS:
77.060 Korozija kovin Corrosion of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 22479
ISO/TC 156
Corrosion of metals and alloys —
Secretariat: SAC
Sulfur dioxide test in a humid
Voting begins on:
atmosphere (fixed gas method)
2026-01-21
Corrosion des métaux et alliages — Essai au dioxyde de soufre en
Voting terminates on:
atmosphère humide (méthode avec volume fixe de gaz)
2026-04-15
ICS: 77.060
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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POTENTIAL TO BECOME STANDARDS TO
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NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 22479:2026(en)
DRAFT
ISO/DIS 22479:2026(en)
International
Standard
ISO/DIS 22479
ISO/TC 156
Corrosion of metals and alloys —
Secretariat: SAC
Sulfur dioxide test in a humid
Voting begins on:
atmosphere (fixed gas method)
Corrosion des métaux et alliages — Essai au dioxyde de soufre en
Voting terminates on:
atmosphère humide (méthode avec volume fixe de gaz)
ICS: 77.060
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
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BE CONSIDERED IN THE LIGHT OF THEIR
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NATIONAL REGULATIONS.
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NOTIFICATION OF ANY RELEVANT PATENT
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Published in Switzerland Reference number
ISO/DIS 22479:2026(en)
ii
ISO/DIS 22479:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
6 Test specimens . 4
6.1 General .4
6.2 Dimensions .4
6.3 Preparation .4
6.3.1 Metals and alloys .4
6.3.2 Paints and varnishes . .4
6.4 Arrangement of the test specimens .4
7 Test conditions . 5
7.1 Test cycles .5
7.2 Test duration .6
8 Procedure . 6
8.1 Introduction of water .6
8.2 Arrangement of the test specimens .6
8.3 Introduction of sulfur dioxide .6
8.4 Heating the test cabinet . .6
8.5 Introduction of standard atmosphere .7
8.6 Replacement of water and sulfur dioxide .7
8.7 Cleaning of test specimens after test.7
8.7.1 General .7
8.7.2 Metals and alloys, metallic and non-organic coating test specimens .7
8.7.3 Organic coating test specimens .7
8.8 Performance check .7
9 Evaluation . 7
10 Test report . 8
Annex A (informative) Another example of a test cabinet . 9
Annex B (informative) Performance check .11
Annex C (informative) Supplemental information .13
Bibliography .15

iii
ISO/DIS 22479:2026(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 documents 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 156, Corrosion of metals and alloys.
This second edition of ISO 22479 cancels and replaces the first edition (ISO 22479:2019), which has been
technically revised. The main changes are as follows:
— the acceptance range of the mass loss in the corrosivity test in Annex B has been slightly adjusted to
[7]
include the historic data from DIN 50018 as well as the data from ISO 22479:2019.
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/DIS 22479:2026(en)
Introduction
A humid atmosphere containing sulfur dioxide induces corrosion of many metals.
The results obtained in this document should not be regarded as a direct guide to the corrosion resistance
of the tested materials in all environments where these materials may be used. Similarly, performances of
different materials in this document should not be taken as a direct guide to the relative corrosion resistance
of these materials in service.
It is appropriate to test only the same corrosion protection systems at the same time in one test procedure,
because an interaction between samples can't be prevented. When testing different corrosion protection
systems with different materials, it should be taken into account that the influence of sulfur dioxide often
can be different.
The term “fixed gas method” means that at the beginning of the test a fixed volume of gas is introduced into
a cabinet of fixed volume.
v
DRAFT International Standard ISO/DIS 22479:2026(en)
Corrosion of metals and alloys — Sulfur dioxide test in a
humid atmosphere (fixed gas method)
WARNING — This document does not purport to address all of the safety concerns, if any, associated
with its use. It is the responsibility of the user of this document to establish appropriate safety and
health practices.
1 Scope
This document specifies a method for assessing the resistance of materials or products to a humid
atmosphere containing sulfur dioxide.
This method is applicable to testing metals and alloys, metallic and non-organic coatings and organic
coatings.
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 1514, Paints and varnishes — Standard panels for testing
ISO 2808, Paints and varnishes — Determination of film thickness
ISO 8044, Corrosion of metals and alloys — Vocabulary
ISO 9223, Corrosion of metals and alloys — Corrosivity of atmospheres — Classification, determination and
estimation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8044 apply.
ISO and IEC maintain terminological 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/
4 Principle
The test specimens are exposed to a humid atmosphere containing sulfur dioxide. The sulfur dioxide
dissolved by the moisture condenses on the test specimen surface and causes corrosion.
5 Apparatus
5.1 Component protection.
All components in contact with sulfur dioxide in a humid atmosphere shall be made of corrosion resistant
materials, and shall themselves not emit any gas or vapour likely to influence corrosion of the test specimens.

ISO/DIS 22479:2026(en)
5.2 Test cabinet.
The preferred capacity of the test cabinet is (300 ± 10) l. When agreed between the interested parties, other
capacities may be used. In these cases, the size and/or number of test specimens, the volume of gas and the
quantity of water shall be properly arranged in accordance with the capacity of the test cabinet.
The upper part of the cabinet shall be designed so that drops of condensed water formed on its surface do
not fall on the test specimens being tested. An inclination of the upper part of the test cabinet of about 12°
or more to the horizontal plane provides a suitable safeguard. The test specimens may be placed at different
levels within the cabinet, as long as the solution does not drip from the test specimens or their supports at
one level onto other test specimens placed below.
The temperature in the test cabinet is controlled by heating the floor and lower part of the side walls of the
test cabinet. The temperature shall be measured at least 250 mm from the side walls and at least 150 mm
below the upper part (lid).
A gas inlet port shall be less than 50 mm above the water surface. The test cabinet shall be hermetically
leak-tight.
A pressure relief valve shall be placed in or near the upper part of the test cabinet.
The exhaust gas and the released gas from the pressure relief valve shall be treated as appropriate.
NOTE Relevant regulatory limitations can apply.
A drain port shall be provided in the test cabinet.
A typical test cabinet is shown in Figure 1. Another example of test cabinet is shown in Figure A.1.
The test cabinet shall be installed in a room free from dust, draughts, corrosive gas and direct solar radiation,
at a room temperature of (23 ± 5) °C and at a relative humidity of less than 75 %.

ISO/DIS 22479:2026(en)
Key
1 lid
2 test specimens
3 specimen supports
4 water inside the cabinet
5 gas inlet port
6 flowmeter
7 source of sulfur dioxide
8 water tank
9 heater
10 drain port
11 pressure relief valve
12 temperature measurement
Figure 1 — Typical test cabinet
5.3 Source of sulfur dioxide.
The source of sulfur dioxide should be a gas cylinder with a volume concentration of more than 99,9 %. It
shall be fitted with appropriate regulating and measuring apparatus to ensure the supply of the correct
volume of gas. The volume of gas delivered into the test cabinet should be measured by a calibrated flow
meter. Another measuring instrument works with squeezing out a viscous liquid paraffin for the volume of
the gas for 0,2, 1,0 and 2,0 l.
1)
WARNING — Sulfur dioxide (CAS Registry Number® 7446-09-5) is toxic, corrosive and irritating.
Handling of sulfur dioxide shall be restricted to skilled personnel or conducted under their control.
The apparatus shall be used and maintained by skilled personnel, not only so that the procedures
can be performed correctly, but also because of the hazards to health and safety that are involved.
1) CAS Registry Number® is a trademark of the American Chemical Society (ACS). This information is given for the
convenience of users of this document and does not constitute an
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