SIST EN ISO 11844-1:2020

SLOVENSKI STANDARD
oSIST prEN ISO 11844-1:2019
01-januar-2019
Korozija kovin in zlitin - Klasifikacija notranjih atmosfer z nizko korozivnostjo - 1.
del: Ugotavljanje in ocenjevanje korozivnosti v zaprtih prostorih (ISO/DIS 11844-
1:2018)
Corrosion of metals and alloys - Classification of low corrosivity of indoor atmospheres -
Part 1: Determination and estimation of indoor corrosivity (ISO/DIS 11844-1:2018)
Korrosion von Metallen und Legierungen - Einteilung der Korrosivität in Räumen mit
geringer Korrosivität - Teil 1: Bestimmung und Abschätzung der Korrosivität in Räumen
(ISO/DIS 11844-1:2018)
Corrosion des métaux et alliages - Classification de la corrosivité faible des atmosphères
d'intérieur - Partie 1: Détermination et estimation de la corrosivité des atmosphères
d'intérieur (ISO/DIS 11844-1:2018)
Ta slovenski standard je istoveten z: prEN ISO 11844-1
ICS:
77.060 Korozija kovin Corrosion of metals
oSIST prEN ISO 11844-1:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 11844-1:2019

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oSIST prEN ISO 11844-1:2019
DRAFT INTERNATIONAL STANDARD
ISO/DIS 11844-1
ISO/TC 156 Secretariat: SAC
Voting begins on: Voting terminates on:
2018-11-12 2019-02-04
Corrosion of metals and alloys — Classification of low
corrosivity of indoor atmospheres —
Part 1:
Determination and estimation of indoor corrosivity
Corrosion des métaux et alliages — Classification de la corrosivité faible des atmosphères d'intérieur —
Partie 1: Détermination et estimation de la corrosivité des atmosphères d'intérieur
ICS: 77.060
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
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STANDARD UNTIL PUBLISHED AS SUCH.
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ISO/DIS 11844-1:2018(E)
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. ISO 2018

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COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2018 – All rights reserved

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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviations . 3
5 Classification of corrosivity . 3
5.1 General . 3
5.2 Categories of indoor corrosivity . 3
6 Determination of indoor atmospheric corrosivity . 3
7 Characterization of indoor atmospheres with respect to indoor corrosivity .4
7.1 General . 4
7.2 Estimation of indoor corrosivity . 5
Annex A (informative) Relation between ISO, IEC and ISA classification systems .8
Annex B (informative) Outdoor and indoor concentrations of some of the most important
pollutants in different types of environments .10
Annex C (informative) General characterisation of metal corrosion in indoor atmospheres .11
Annex D (informative) Guideline for estimation of indoor corrosivity .13
Bibliography .17
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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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
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.
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.
This document was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
This second edition cancels and replaces the first edition (ISO 11844-1:2006), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— reference to ISO 16000 in the Clause 7 has been added;
— the model estimates the indoor concentration and deposition of pollutants originating from outdoors
was added;
— lead was included as standard specimen with high sensitivity to vapour organic acids.
A list of all parts in the ISO 11844- series can be found on the ISO website.
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Introduction
Metals, alloys and metallic coatings are subject to atmospheric corrosion under the impact of air
humidity, especially when gaseous and solid substances of atmospheric pollution co-impact. Corrosivity
data are of fundamental importance for derivation of suitable corrosion protection, or for evaluation of
serviceability of metal elements of a product.
ISO 9223 classifies the atmospheric environment into six corrosivity categories.
Low-corrosivity indoor atmospheres are indoor atmospheres with C 1 (very low) or C 2 (low) corrosivity
categories according to ISO 9223.
The classification in ISO 9223 is too broad for some purposes in low-corrosivity indoor atmospheres,
e.g. places where electronic devices, sophisticated technical products, or works of art and historical
objects are stored.
For such purposes, it is necessary to subdivide the corrosivity categories C 1 (very low) and C 2 (low)
into indoor corrosivity categories in this document.
The evaluation of low-corrosivity indoor atmospheres can be accomplished by direct determination of
corrosion attack of selected metals (see ISO 11844-2) or by measurement of environmental parameters
(see ISO 11844-3) which may cause corrosion on metals and alloys.
This document describes general procedures for derivation and estimation of indoor corrosivity
categories.
A general approach to classification of corrosivity in indoor atmospheres is given in the scheme shown
in Figure 1.
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Figure 1 — Scheme for classification of low corrosivity in indoor atmospheres
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oSIST prEN ISO 11844-1:2019
DRAFT INTERNATIONAL STANDARD ISO/DIS 11844-1:2018(E)
Corrosion of metals and alloys — Classification of low
corrosivity of indoor atmospheres —
Part 1:
Determination and estimation of indoor corrosivity
1 Scope
This document deals with the classification of low corrosivity of indoor atmospheres.
The aim of this document is to characterise indoor atmospheric environments of low corrosivity that
can affect metals and metallic coatings during storage, transport, installation or operational use, to set
a consistent way of indoor corrosivity classification, and to prescribe procedures for derivation and
estimation of indoor corrosivity categories.
This document specifies technical metals, whose corrosion attack after a defined exposure period is
used for determination of corrosivity categories of indoor atmospheres of low corrosivity.
This document defines corrosivity categories of indoor atmospheres according to corrosion attack on
standard specimens.
This document indicates important parameters of indoor atmospheres that can serve as a basis for an
estimation of indoor corrosivity.
Selection of a method for determination of corrosion attack, description of standard specimens, its
exposure conditions and evaluation are the subject of ISO 11844-2. Measurement of environmental
parameters affecting indoor corrosivity is the subject of ISO 11844-3.
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 8044, Corrosion of metals and alloys — Basic terms and definitions
ISO 9223, Corrosion of metals and alloys — Corrosivity of atmospheres — Classification, determination
and estimation
ISO 11844-2, Corrosion of metals and alloys — Classification of low corrosivity of indoor atmospheres —
Part 2: Determination of corrosion attack in indoor atmospheres
ISO 11844-3, Corrosion of metals and alloys — Classification of low corrosivity of indoor atmospheres —
Part 3: Measurement of environmental parameters affecting indoor corrosivity
ISO 16000 (all parts), Indoor air
ISO 16000-1:2004, Indoor air — Part 1: General aspects of sampling strategy
IEC 60654-4:1987, Operating conditions for industrial-process measurement and control equipment —
Part 4: Corrosive and erosive influences
IEC 60721 (all parts), Classification of environmental conditions
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3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
climate
statistics of temperature, humidity, atmospheric pressure, wind, rainfall, and other meteorological
elements in a given location over a long period of time
3.2
atmosphere
mixture of gases, aerosols and particles, that surrounds a given material/object/structure
3.3
indoor atmosphere/environment
atmosphere/environment (combined effect of climate and atmosphere) inside a box, a room or a building
3.4
microclimate
the climate of a small area, specific rooms, part of building, etc. which may be different from that in the
general region
3.5
temperature-humidity complex
combined effect of temperature and relative humidity on the corrosivity of the atmosphere
[SOURCE: ISO 9223:2012, definition 3.4]
3.6
time of wetness
period during which a metallic surface is covered by adsorptive and/or liquid films of electrolyte that
are capable of causing atmospheric corrosion
[SOURCE: ISO 9223:2012, definition 3.5]
3.7
atmospheric pollution
specific corrosion-active substances, gases or suspended particles in the air (both natural and the
result of human activity)
3.8
corrosion system
system consisting of one or more metals and those parts of environment that influence corrosion
3.9
corrosion damage
corrosion effect that causes impairment of the function of the metal, the environment or the technical
system of which these form a part
3.10
corrosivity
ability of an environment to cause corrosion of a metal in a given corrosion system
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3.11
corrosivity of atmospheres
ability of the atmosphere to cause corrosion in a given corrosion system (e.g. atmospheric corrosion of
a given metal or alloy)
[SOURCE: ISO 9223:2012, definition 3.1]
4 Symbols and abbreviations
IC corrosivity categories of indoor atmospheres.
r corrosion rate derived from mass-loss measurement after an exposure of one year.
corr
r rate of mass increase after an exposure of one year.
mi
5 Classification of corrosivity
5.1 General
The corrosivity of indoor atmospheres can be classified either by determination of the corrosion attack
on standard specimens of selected standard metals as given in Clause 6 or, where this is not possible, by
estimation of corrosivity based on the knowledge of humidity, temperature and pollution conditions as
described in Clause 7 and Annexes B, C and D.
Estimation of corrosivity as described in 7.2 and Annexes C and D may lead to wrong conclusions.
Therefore, the determination of corrosivity by measurement of the corrosion attack on standard
specimens is strongly recommended.
5.2 Categories of indoor corrosivity
For the purpose of this document, indoor atmospheres are classified into five corrosivity categories
denoted IC 1 to IC 5. The classification is given in Table 1.
Table 1 — Corrosivity categories of indoor atmospheres
Indoor corrosivity category
IC 1 Very low indoor corrosivity
IC 2 Low indoor corrosivity
IC 3 Medium indoor corrosivity
IC 4 High indoor corrosivity
IC 5 Very high indoor corrosivity
6 Determination of indoor atmospheric corrosivity
The determination of corrosivity of indoor atmospheres is based on measurements of corrosion attack
on standard specimens of four reference metals after an exposure for one year in accordance with
ISO 11844-2. From the mass loss or mass increase, the indoor corrosivity category for each metal is
determined from Table 2.
In indoor environments when the all conditions (temperature, humidity, air pollutions) vary only in
range of ±5 % from average value, the exposure period should be shorter, e.g. one month only. It is
preferably this month represents the most corrosive period of year.
Metals complement each other in the classification of indoor corrosivity for a given environment.
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7 Characterization of indoor atmospheres with respect to indoor corrosivity
7.1 General
Environmental characteristics are informative and allow assessment of specific corrosion effects with
regard to individual metals and metallic coatings.
The ISO 16000 (all parts) deals with indoor air measurements describing the sampling strategy,
including the conditions to be observed for the particular substances or groups of substances, such as
the dependence of indoor air pollution concentrations on atmospheric humidity or temperature or other
effects. Table A.1 of ISO 16000-1:2004 summarizes the most important types of indoor environment, and
examples of the sources that may be encountered in them. The list is not, of course, fully comprehensive
because of the large number of possibilities. Table B.1 shows the sources of indoor air pollutants and the
most important substances emitted. Table C.1 lists substances frequently detected and their possible
sources. ISO 16000 (all parts) does not cover all indoor air pollutants significant for indoor atmospheric
corrosivity.
Methods for characterization and measurement of environmental parameters in indoor atmospheres
are given in ISO 11844-3.
This method of corrosivity estimation is, in many cases, oversimplified and may give misleading results.
An estimation of corrosivity is based on:
— climatic influences (outdoor situation including pollution),
— indoor microclimate influences, and
— indoor gaseous and particle pollution.
The corrosivity of an indoor atmosphere increases with higher humidity and depends on the type and
level of pollution.
Frequency of variation of relative humidity (RH) and temperature (T) in intervals, and frequency and
time of condensation, are important characteristics.
An indoor environment is rarely static, since the concentration of any substance may be constantly
altered by the strength of the source, human activity, ventilation rate, external or internal climatic
conditions, chemical reactions and possible sinks (e.g. sorption by surfaces and furnishings). In addition,
the composition of indoor air may vary within and between rooms, and be less homogeneous than the
outdoor air surrounding the building.
Indoor atmospheres are polluted by the components from external and internal sources. Typical
- +
pollutants are SO , NO , O , H S, Cl , NH , HCl, HNO , Cl , NH , organic acids, aldehydes and particles
2 2 3 2 2 3 3 4
(see informative Annex B). Due to the permanent exchange between indoor and outdoor air caused by
infiltration and ventilation processes, it may be important to supplement indoor air measurements with
a simultaneous measurement of the outdoor air (if possible at the same level (floor) of the building). The
outdoor air samples should be taken in the vicinity of the building but not closer than 1 m. In making
such measurements, it should be remembered that vertical concentration gradients may occur, for
example for the components of vehicle exhaust gases in street canyons.
The air exchange of a building, whether it is due to mechanical ventilation, natural ventilation or
infiltration can have a significant influence on the indoor atmosphere. The model estimates the indoor
concentration and deposition of pollutants originating from outdoors was derived for the steady-state
indoor/outdoor (I/O) relation of various gaseous pollutions in buildings:
C n
i
I/O == (1)
A
C  
o
nv+
d  
V
 

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where
-3
C is the indoor concentration of pollutant [μg.m ];
i
-3
C is the outdoor concentration of pollutant [μg.m ];
o
-1
n is the air exchange rate [h ];
-1
v is the deposition velocity [m.h ];
d
2
A is the inside surface area of room [m ];
3
V is the volume of room [m ].
The typical I/O ratio of sulfur dioxide is ca 0,50. The typical I/O ratio of nitrogen dioxide is in the range
of 0,60 to 0,80. There are exceptions: at sites with a low air exchange rate, or with chemical air-filtration,
the I/O ratio can be less than 0,10. The matching indoor/outdoor (I/O) concentration ratios for ozone
show the same trend, with the typical I/O ratio below 0,7, and half of these I/O ratios even below 0,20.
For indoor conditions, volatile organic acids such as formic acid (HCOOH), acetic acid (CH COOH), and
3
propionic acid (CH CH COOH) may have a significant influence on indoor corrosivity. Carboxylic acids
3 2
in the atmosphere may exist as anthropogenic and/or biogenic air pollution, from automotive exhaust,
biomass combustion for domestic and industrial heating, vegetation, organic coatings or emanating
from the oceans. Other sources may be photochemical oxidation of organic species in air or water.
Corrosion for many of the metals is significantly influenced by the synergistic effects of different
pollutants.
Metals and metallic coatings have their own specific corrosion behaviour in indoor atmospheres (see
Annex C).
7.2 Estimation of indoor corrosivity
7.2.1 Characterization of the environment summarised in a guideline (Annex D), forms a basis for
indoor corrosivity estimation. Description of typical environments related to the estimation of indoor
corrosivity categories is presented in Table D.3.
7.2.2 Important factors of indoor corrosion are defined as the highest levels of measured environmental
parameters and as a description of other and specific environmental influences affecting indoor corrosion
of metals.
7.2.3 The determination of indoor corrosivity categories is illustrated in Tables 2 and 3.
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6 © ISO 2018 – All rights reserved
Table 2 — Classification of corrosivity of indoor atmospheres based on corrosion rate measurements by mass loss determination of
standard specimens
2
Corrosion rate (r ) [mg/(m -a)]
corr
Corrosivity category
Carbon steel Zinc Copper Silver Lead
IC 1 Very low indoor r ≤ 70 r ≤ 50 r ≤ 50 r ≤ 170 r ≤ 40
corr corr corr corr corr
IC 2 Low indoor 70 < r ≤ 1 000 50 < r ≤ 250 50 < r ≤ 200 170 < r ≤ 670 40 < r ≤ 150
corr corr corr corr corr
IC 3 Medium indoor 1 000 < r ≤ 10 000 250 < r ≤ 700 200 < r ≤ 900 670 < r ≤ 3 000 150 < r ≤ 400
corr corr corr corr corr
IC 4 High indoor 10 000 < r ≤ 70 000 700 < r ≤ 2 500 900 < r ≤ 2 000 3 000 < r ≤ 6 700 400 < r ≤ 700
corr corr corr corr corr
IC 5 Very high indoor 70 000 < r ≤ 200 000 2 500 < r ≤ 5 000 2 000 < r ≤ 5 000 6 700 < r ≤ 16 700 700 < r ≤ 1 600
corr corr corr corr corr


Table 3 — Classification of corrosivity of indoor atmospheres based on rate of mass increase measured with standard specimens
2
Rate of mass increase (r ) [mg/(m -a)]
mi
Corrosivity category
Carbon steel Zinc Copper Silver Lead
IC 1 Very low indoor r ≤ 70 r ≤ 50 r ≤ 25 r ≤ 25 -
mi mi mi mi
IC 2 Low indoor 70 < r ≤ 700 50 < r ≤ 250 25 < r ≤ 100 25 < r ≤ 100 -
mi mi mi mi
IC 3 Medium indoor 700 < r ≤ 7 000 250 < r ≤ 700 100 r ≤ 450 100 < r ≤ 450 -
mi mi mi mi
IC 4 High indoor 7 000 r ≤ 50 000 700 < r ≤ 2 500 450 < r ≤ 1 000 450 < r ≤ 1 000 -
mi mi mi mi
IC 5 Very high indoor 50 000 < r ≤ 150 000 2 500 < r ≤ 5 000 1 000 < r ≤ 2 500 1 000 < r ≤ 2 500 -
mi mi mi mi
NOTE 1   The specification of standard specimens of carbon steel, zinc, copper and silver, and the procedures for evaluation of the mass change is given in
ISO 11844-2.
NOTE 2   Corrosion rate measurements by mass loss determination of standard specimens (Table 2) are preferably used for higher indoor corrosivity catego-
ries. Also, in atmospheres where a high deposition of particles is expected, the mass loss determination is preferred.
NOTE 3   An approximate relation between the corrosivity categories in this part of ISO 11844, and severity levels in ANSI/ISA –S71.04-1985, is given in
Annex A.
NOTE 4   The upper limit of corrosivity category IC 3 corresponds roughly to the upper limit of corrosivity category C 1 according to ISO 9223.
NOTE 5   The upper limit of corrosivity category IC 5 corresponds roughly to the upper limit of corrosivity category C 2 according to ISO 9223.

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Annex A
(informative)

Relation between ISO, IEC and ISA classification systems
ISO 9223, IEC 60654-4:1987, Appendix B and ANSI/ISA S71.04-1985 all include corrosion rate
determination for classifying environmental conditions.
ISO 9223 gives corrosivity categories based on corrosion of carbon steel, zinc, copper and aluminium,
expressed as mass loss after one year of exposure.
IEC 60654-4:1987, Appendix B classifies the reactivity of the environment, measuring corrosion film
thickness on copper after 30 days of exposure.
ANSI/ISA S71.04-1985 gives severity levels, based on copper corrosion measured as corrosion film
thickness after 30 days of exposure.
In order to compare these classification systems, corrosion figures for copper are selected, copper being
the only metal common to all standards. Furthermore, all corrosion rates have to be transformed to
the same unit. Corrosion figures given in the standards are first expressed as mass increase. Secondly,
for the IEC and ISA standards, mass increase after 30 days of exposure is transformed to one year.
The correlation between 30 days and one year of exposure is graphically presented in Figure A.1. The
graphical representation is based on expressions given in the IEC and ISA standards.
Please note that extrapolation in time is not very reliable and cannot be done at all for low corrosion rates.
Key
2
X mass increase after 30 days of exposure (mg/m )
2
Y mass increase after one year of exposure (mg/m )
Figure A.1 — Copper mass increase, transformation between 30 days and one year of exposure
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In Figure A.2, the classification systems of the different standards are compared. The comparison
is based on copper corrosion rate, assuming that CuO, Cu SO (OH) and Cu S are the predominant
4 4 6 2
corrosion products. Corrosion rate figures given in the standards are all transformed to copper mass
increase after one year of exposure.
Key
-2
Y mass increase after one year of exposure (mg.m )
Figure A.2 — Copper corrosivity classification according to ISO, IEC and ISA
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Annex B
(informative)

Outdoor and indoor concentrations of some of the most important
pollutants in different types of environments
Table B.1 — Outdoor and indoor concentrations of some of the most important pollutants in
different types of environments
-3
Concentration (yearly average value) (µg.m )
Pollutant
outdoor indoor
rural: 2 to 15 non-process roo
...