ISO/FDIS 14993

FINAL DRAFT
International
Standard
ISO/TC 156
Corrosion of metals and alloys —
Secretariat: SAC
Accelerated testing involving cyclic
Voting begins on:
exposure to salt mist, dry and wet
2026-01-22
conditions
Voting terminates on:
2026-03-19
Corrosion des métaux et alliages — Essais accélérés comprenant
des expositions cycliques à des conditions de brouillard salin, de
séchage et d'humidité
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
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TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 156
Corrosion of metals and alloys —
Secretariat: SAC
Accelerated testing involving cyclic
Voting begins on:
exposure to salt mist, dry and wet
conditions
Voting terminates on:
Corrosion des métaux et alliages — Essais accélérés comprenant
des expositions cycliques à des conditions de brouillard salin, de
séchage et d'humidité
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 SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
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BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
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INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
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TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Test solution . 2
4.1 General .2
4.2 Preparation of the sodium chloride solution .2
4.3 pH adjustment .2
5 Apparatus . 3
5.1 Component protection .3
5.2 Exposure equipment .3
6 Test specimens . 4
7 Arrangement of the test specimens . 4
8 Operating conditions . 5
9 Continuity of tests. 6
10 Duration of tests . 6
11 Treatment of test specimens after testing . 6
11.1 General .6
11.2 Non-organic coated test specimens: Metallic and/or inorganic coated .6
11.3 Organic coated test specimens .6
11.3.1 Scribed organic coated test specimens .6
11.3.2 Organic coated but not scribed test specimens .7
12 Evaluation of results . 7
13 Test report . 7
Annex A (informative) Typical apparatus for cyclic salt mist, dry and wet corrosion tests . 9
Annex B (informative) Method for evaluation of the corrosivity of the apparatus .11
Annex C (normative) Preparation of test specimens with organic coatings for testing .13
Annex D (normative) Required supplementary information for testing test specimens with
organic coatings. 14
Bibliography .15

iii
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 third edition cancels and replaces the second edition (ISO 14993:2018), which has been technically
revised.
The main changes are as follows:
— safety warnings have been added;
— apparatus has been revised to harmonize with ISO 16151.
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
Introduction
Corrosion of metallic materials with or without corrosion protection is influenced by many environmental
factors, the importance of which can vary depending on the type of metallic material and the type of
environment. It is impossible, therefore, to design accelerated laboratory corrosion tests in such a way
that all environmental factors influencing resistance to corrosion are taken into account. Laboratory tests
are, therefore, designed to simulate the effects of the most important factors that enhance the corrosion
of metallic materials, however it is not possible to design a laboratory corrosion test in such a way that
complexity and variations of real, in-service conditions are fully represented.
The accelerated corrosion test method described in this document is designed to simulate and enhance the
environmental influence on a metallic material of exposure to an outdoor climate, where exposure to salt-
contaminated conditions occurs and can promote corrosion.
The test method involves cyclic exposure of test specimens to a mist of salt solution, to drying conditions
and to periods of high humidity. They are not intended to be used for comparative testing or as a means
of ranking different materials relative to each other with respect to corrosion resistance or as means of
predicting long-term corrosion resistance of the tested material (merely for testing the whole product). And
the results obtained do not permit far-reaching conclusions on the corrosion resistance of the tested metallic
material under the whole range of environmental conditions within which it can be used. Nevertheless, the
method gives a means of checking that comparative quality of a metallic material, with or without corrosion
protection, is maintained when exposed to salt-contaminated environments similar to those used in the
[15]
test .
This test method is based on Japanese Automobile Standards JASO M 609-91 and JASO M 610-92.

v
FINAL DRAFT International Standard ISO/FDIS 14993:2026(en)
Corrosion of metals and alloys — Accelerated testing
involving cyclic exposure to salt mist, dry and wet conditions
WARNING — This document can involve hazardous materials, operations and equipment. 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
and determine the applicability of regulatory limitations prior to use.
1 Scope
This document specifies the apparatus and test procedure to be used when conducting accelerated corrosion
tests for the comparative quality evaluation of metallic materials with or without permanent corrosion
protection or temporary corrosion protection in salt-contaminated outdoor environments. The test involves
cyclic exposure of the specimens to neutral salt mist, “dry” and “wet” conditions. The type of test specimen
and the exposure period are not specified.
The particular advantages of this test over common accelerated tests such as the neutral salt spray (NSS) test
lie in its ability to better reproduce the corrosion that occurs in outdoor salt-contaminated environments.
This document is applicable to:
— metals and their alloys;
— metallic coatings (anodic and cathodic);
— conversion coatings;
— anodic oxide coatings;
— organic coatings on metallic materials.
NOTE Methods of test for coatings to determine their resistance, in the presence of scribe marks through to the
substrate, to various cyclic corrosion conditions which include the condensation of water on the test specimens during
periods of humidity are given in ISO 11997-1.
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 4623-2:2016, Paints and varnishes — Determination of resistance to filiform corrosion — Part 2: Aluminium
substrates
ISO 8044, Corrosion of metals and alloys — Vocabulary
ISO 17872, Paints and varnishes — Guidelines for the introduction of scribe marks through coatings on metallic
panels for corrosion testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8044 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
reference specimen
portion of the material with known test performance that is to be exposed with the intention to check the
reproducibility and repeatability of the test results for the test cabinet in use
3.2
test specimen
specific portion of the samples upon which the testing is to be performed
3.3
substitute specimen
specimen made of inert materials (such as plastic or glass) used for the substitute of a test specimen (3.2)
4 Test solution
4.1 General
Instructions for the preparation and use of a neutral sodium chloride solution are given in 4.2 and 4.3.
4.2 Preparation of the sodium chloride solution
Dissolve a sufficient mass of sodium chloride in distilled or deionized water with a conductivity no higher
than 20 μS/cm at 25 °C ± 2 °C to produce a concentration of 50 g/l ± 5 g/l. The sodium chloride concentration
of the sprayed solution collected shall be 50 g/l ± 5 g/l. The specific gravity range for a 50 g/l ± 5 g/l solution
is 1,029 to 1,036 at 25 °C.
The sodium chloride shall not contain a mass fraction of the heavy metals of copper (Cu), nickel (Ni) and lead
(Pb) in total more than 0,005 %. It shall not contain a mass fraction of sodium iodide more than 0,1 % and a
mass fraction of total impurities more than 0,5 %, calculated for dry salt.
NOTE Sodium chloride with anti-caking agents can act as corrosion inhibitors or accelerators. A useful sodium
chloride salt grade is a grade named Ph. Eur/USP or JIS, ACS.
4.3 pH adjustment
Adjust the pH of the salt solution so that the pH of the sprayed solution collected within the test cabinet is
6,5 to 7,2 at 25 °C ± 2 °C. Check the pH using electrometric measurement. Measurements of pH shall be done
using electrode suitable for measuring in weakly buffered sodium chloride solutions in deionized water.
Make any necessary corrections by adding hydrochloric acid, sodium hydroxide or sodium bicarbonate
solution of analytical grade.
®1)
WARNING — Hydrochloric acid (CAS Registry Number 7647-01-0) solution is toxic, corrosive,
irritating and very toxic to aquatic life. Refer to the safety data sheet for details. Handling of
hydrochloric acid solution shall be restricted to skilled personnel or conducted under their control.
Care shall be taken in the disposal of this solution. ®
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 endorsement by ISO of the product named. Equivalent
products may be used if they can be shown to lead to the same results.

WARNING — Sodium hydroxide (CAS 1310-73-2) solution is toxic, corrosive and irritating. Refer to
the safety data sheet for details. Handling of sodium hydroxide solution shall be restricted to skilled
personnel or conducted under their control. Care shall be taken in the disposal of this solution.
NOTE Possible changes in pH can result from loss of carbon dioxide from the solution when it is sprayed.
Such changes can be avoided by reducing the carbon dioxide content of the solution by, for example, heating it to a
temperature greater than 35 °C before it is placed in the apparatus, or by making the solution from freshly boiled
water.
5 Apparatus
5.1 Component protection
All components in contact with the salt mist spray or the test solution shall be made of, or lined with,
materials which are resistant to corrosion by the test solution and which do not influence the corrosivity of
the sprayed test solution.
The supports for the test specimen shall be constructed such that different substrate types do not influence
each other. It shall also be constructed so that the supports themselves do not influence the test specimens.
5.2 Exposure equipment
5.2.1 Test cabinet, that meets the conditions of homogeneity and distribution of the spray. Due to the
limited capacity of test cabinets smaller than 0,4 m , the effect of the loading of the test cabinet on the
distribution of the spray and temperature shall be carefully considered. The solution shall not be sprayed
directly onto test specimens but rather spread throughout the test cabinet so that it falls naturally down on
them. The upper parts of the test cabinet shall be designed so that drops of sprayed solution formed on its
surface do not fall on the specimens being tested.
The size and shape of the test cabinet shall be such that during periods of exposure to salt mist spray, the
collection rate of solution in the test cabinet is within the limits specified in 8.2.
NOTE A schematic diagram of one possible design of test cabinet and associated apparatus for salt mist cyclic
corrosion testing is shown in Annex A.
5.2.2 Humidity and temperature control system, being capable of achieving the test condition
transition times listed in 8.1 when the test cabinet is filled with flat substitute specimens having a dimension
of 150 mm × 70 mm × 1 mm.
5.2.3 Spraying device, for spraying the salt solution during periods of exposure to salt mist spray
comprising a supply of air at controlled pressure, a reservoir containing the solution to be sprayed and one
or more atomizers.
The compressed air supplied to the atomizers shall be passed through a filter to remove all traces of oil or
solid matter and shall be at an overpressure of 70 kPa to 170 kPa. The pressure is typically 98 kPa ± 10 kPa
but can vary depending on the type of test cabinet and atomizer used.
5.2.4 Air saturator, consisting of a saturation tower containing hot water at a temperature higher than
that of the test cabinet. In order to prevent evaporation of water from the sprayed droplets, the air shall be
humidified before entering the atomizer, by passage through this tower.
During periods of exposure to the salt mist, the appropriate temperature depends on the pressure used and
on the type of atomizer nozzle and shall be adjusted so that the rate of collection of spray in the test cabinet
and the concentration of the collected spray are kept to within the specified limits (see 8.2). The level of
water shall be maintained automatically to ensure adequate humidification.
The atomizers shall be made of inert material, e.g. glass or plastic materials. Baffles may be used to prevent
direct impact of spray on the test specimens and the use of adjustable baffles is helpful in obtaining constant

distribution of spray within the test cabinet. The level of the salt solution in the supply tank shall be
maintained automatically to ensure constant spray delivery throughout the test.
5.2.5 Collecting devices, at least two, consisting of clean funnels with a collecting area of approximately
80 cm made of glass or other chemically inert material, with the stems inserted into graduated cylinders or
other similar containers. The purpose of the collecting devices is to confirm that the collection rate is within
specified limits (see 8.2). They shall be placed in the zone of the test cabinet where the test specimens are
placed, one close to the spray inlet and one remote from an inlet and in such a way that only spray, and not
the liquid falling from specimens or from parts of the test cabinet, is collected.
5.2.6 Air dryer, comprising a heating device and fan to supply dried air of the specified humidity during
“dry” periods (see Table 1).
5.2.7 Exhaust system, by which air is exhausted from the test cabinet. It shall not be influenced by the
back pressure of the atmosphere when the air is released at a point outside the building.
6 Test specimens
6.1 The number and type of test specimens, their
...