Corrosion of metals and alloys - Classification of low corrosivity of indoor atmospheres - Part 1: Determination and estimation of indoor corrosivity (ISO 11844-1:2020)

This document establishes a classification of low corrosivity of indoor atmospheres.
It specifies the reference metals for which a corrosion attack after a defined exposure period is used for
determining corrosivity categories of indoor atmospheres of low corrosivity.
It defines corrosivity categories of indoor atmospheres according to corrosion attack on standard
specimens.
It indicates important parameters of indoor atmospheres that can serve as a basis for an estimation of
indoor corrosivity.
The selection of a method for the determination of corrosion attack, description of standard specimens,
exposure conditions and evaluation are given in ISO 11844-2. The measurement of environmental
parameters affecting indoor corrosivity is given in ISO 11844-3.

Korrosion von Metallen und Legierungen - Einteilung der Korrosivität in Räumen mit geringer Korrosivität - Teil 1: Bestimmung und Abschätzung der Korrosivität in Räumen (ISO 11844-1:2020)

Dieses Dokument legt eine Einteilung der Korrosivität von Atmosphären in Innenräumen mit geringer Korrosivität fest.
Es legt die Bezugsmetalle fest, für die ein Korrosionsangriff nach einer bestimmten Auslagerungsdauer zur Bestimmung der Korrosivitätskategorie für eine Atmosphäre in Innenräumen mit geringer Korrosivität angewendet wird.
Es definiert die Korrosivitätskategorien für die Atmosphäre in Innenräumen durch Bestimmung des Korrosionsangriffes von Standardproben.
Es gibt wichtige Parameter für die Atmosphären in Innenräumen an, die als Grundlage für eine Abschätzung der Korrosivität in Innenräumen verwendet werden können.
Die Auswahl eines Verfahrens zur Bestimmung des Korrosionsangriffes, die Beschreibung der Standard¬proben, die Auslagerungsbedingungen und die Auswertung sind in ISO 11844 2 angegeben. Die Messung von Umgebungsparametern, die Einfluss auf die Korrosivität in Innenräumen haben, ist in ISO 11844 3 angegeben.

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 11844-1:2020)

Le présent document établit une classification des atmosphères d'intérieur à faible corrosivité.
Il spécifie les métaux de référence pour lesquels une attaque de corrosion, au terme d'une durée d'exposition définie, sert à déterminer les catégories de corrosivité des atmosphères d'intérieur à faible corrosivité.
Il définit les catégories de corrosivité des atmosphères d'intérieur en fonction de l'attaque de corrosion qu'elles provoquent sur des éprouvettes normalisées.
Il indique des paramètres importants des atmosphères d'intérieur pouvant servir de base à une estimation de leur corrosivité.
Le choix d'une méthode de détermination de l'attaque de corrosion, la description des éprouvettes normalisées et les conditions d'exposition et d'évaluation sont donnés dans l'ISO 11844-2. Le mesurage des paramètres environnementaux affectant la corrosivité des atmosphères d'intérieur est donné dans l'ISO 11844-3.

Korozija kovin in zlitin - Klasifikacija notranjih atmosfer z nizko korozivnostjo - 1. del: Ugotavljanje in ocenjevanje korozivnosti v zaprtih prostorih (ISO 11844-1:2020)

General Information

Status
Published
Public Enquiry End Date
24-Jan-2019
Publication Date
10-Aug-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
14-Jul-2020
Due Date
18-Sep-2020
Completion Date
11-Aug-2020

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SLOVENSKI STANDARD
SIST EN ISO 11844-1:2020
01-september-2020
Nadomešča:
SIST EN ISO 11844-1:2008

Korozija kovin in zlitin - Klasifikacija notranjih atmosfer z nizko korozivnostjo - 1.

del: Ugotavljanje in ocenjevanje korozivnosti v zaprtih prostorih (ISO 11844-
1:2020)

Corrosion of metals and alloys - Classification of low corrosivity of indoor atmospheres -

Part 1: Determination and estimation of indoor corrosivity (ISO 11844-1:2020)

Korrosion von Metallen und Legierungen - Einteilung der Korrosivität in Räumen mit

geringer Korrosivität - Teil 1: Bestimmung und Abschätzung der Korrosivität in Räumen

(ISO 11844-1:2020)

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 11844-1:2020)
Ta slovenski standard je istoveten z: EN ISO 11844-1:2020
ICS:
77.060 Korozija kovin Corrosion of metals
SIST EN ISO 11844-1:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11844-1:2020
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SIST EN ISO 11844-1:2020
EN ISO 11844-1
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2020
EUROPÄISCHE NORM
ICS 77.060 Supersedes EN ISO 11844-1:2008
English Version
Corrosion of metals and alloys - Classification of low
corrosivity of indoor atmospheres - Part 1: Determination
and estimation of indoor corrosivity (ISO 11844-1:2020)

Corrosion des métaux et alliages - Classification de la Korrosion von Metallen und Legierungen - Einteilung

corrosivité faible des atmosphères d'intérieur - Partie der Korrosivität in Räumen mit geringer Korrosivität -

1: Détermination et estimation de la corrosivité des Teil 1: Bestimmung und Abschätzung der Korrosivität

atmosphères d'intérieur (ISO 11844-1:2020) in Räumen (ISO 11844-1:2020)
This European Standard was approved by CEN on 25 May 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

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, Turkey 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

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11844-1:2020 E

worldwide for CEN national Members.
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SIST EN ISO 11844-1:2020
EN ISO 11844-1:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 11844-1:2020
EN ISO 11844-1:2020 (E)
European foreword

This document (EN ISO 11844-1:2020) has been prepared by Technical Committee ISO/TC 156

"Corrosion of metals and alloys" in collaboration with Technical Committee CEN/TC 262 “Metallic and

other inorganic coatings, including for corrosion protection and corrosion testing of metals and alloys”

the secretariat of which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by December 2020, and conflicting national standards

shall be withdrawn at the latest by December 2020.

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.

This document supersedes EN ISO 11844-1:2008.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: 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, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 11844-1:2020 has been approved by CEN as EN ISO 11844-1:2020 without any

modification.
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SIST EN ISO 11844-1:2020
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SIST EN ISO 11844-1:2020
INTERNATIONAL ISO
STANDARD 11844-1
Second edition
2020-05
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
Reference number
ISO 11844-1:2020(E)
ISO 2020
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 2

5 Classification of corrosivity ....................................................................................................................................................................... 2

5.1 General ........................................................................................................................................................................................................... 2

5.2 Categories of indoor corrosivity .............................................................................................................................................. 3

6 Determination of indoor atmospheric corrosivity ........................................................................................................... 3

7 Characterization of indoor atmospheres with respect to indoor corrosivity .......................................3

7.1 General ........................................................................................................................................................................................................... 3

7.2 Estimation of indoor corrosivity ............................................................................................................................................. 5

Annex A (informative) Relationship 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 ....................................................................................................................11

Annex C (informative) General characterization of metal corrosion in indoor atmospheres ...............12

Annex D (informative) Guidelines for the estimation of indoor corrosivity ............................................................15

Bibliography .............................................................................................................................................................................................................................19

© ISO 2020 – All rights reserved iii
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
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.

This document was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys, in

collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/

TC 262, Metallic and other inorganic coatings, including for corrosion protection and corrosion testing of

metals and alloys, in accordance with the Agreement on technical cooperation between ISO and CEN

(Vienna Agreement).

This second edition cancels and replaces the first edition (ISO 11844-1:2006), which has been

technically revised. The main changes compared with the previous edition are as follows:

— a reference to the ISO 16000 series in Clause 7 has been added;

— a model that estimates the indoor concentration and deposition of pollutants originating from

outdoors has been added;

— lead has been included as a 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.

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 2020 – All rights reserved
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
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 in accordance with 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 the indoor corrosivity categories given 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) that can cause corrosion on metals and alloys.

This document describes general procedures for derivation and estimation of indoor corrosivity

categories.

The aim of this document is to characterize 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.

A general approach to the classification of corrosivity of indoor atmospheres is given in the scheme

shown in Figure 1.
© ISO 2020 – All rights reserved v
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
Figure 1 — Scheme for classification of low corrosivity of indoor atmospheres
vi © ISO 2020 – All rights reserved
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SIST EN ISO 11844-1:2020
INTERNATIONAL STANDARD ISO 11844-1:2020(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 establishes a classification of low corrosivity of indoor atmospheres.

It specifies the reference metals for which a corrosion attack after a defined exposure period is used for

determining corrosivity categories of indoor atmospheres of low corrosivity.

It defines corrosivity categories of indoor atmospheres according to corrosion attack on standard

specimens.

It indicates important parameters of indoor atmospheres that can serve as a basis for an estimation of

indoor corrosivity.

The selection of a method for the determination of corrosion attack, description of standard specimens,

exposure conditions and evaluation are given in ISO 11844-2. The measurement of environmental

parameters affecting indoor corrosivity is given in ISO 11844-3.
2 Normative references
There are no normative references in this document.
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:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
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
[SOURCE: EN 15759-1:2011, 3.1]
3.2
atmosphere

mixture of gases, aerosols and particles that surrounds a given material, object or structure

3.3
indoor atmosphere

environment [combined effect of climate (3.1) and atmosphere (3.2)] inside a box, a room or a building

© ISO 2020 – All rights reserved 1
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
3.4
microclimate

climate (3.1) 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 (3.10)

[SOURCE: ISO 9223:2012, 3.4]
3.6
time of wetness

period when a metallic surface is covered by adsorptive and/or liquid films of electrolyte to be capable

of causing atmospheric corrosion
[SOURCE: ISO 9223:2012, 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 the environment that influence corrosion

[SOURCE: ISO 8044:2020, 3.4, modified — Note 1 to entry has been deleted.]
3.9
corrosivity

ability of an environment to cause corrosion of a metal in a given corrosion system (3.8)

[SOURCE: ISO 8044:2020, 3.14]
3.10
corrosivity of atmosphere
ability of the atmosphere to cause corrosion in a given corrosion system (3.8)
EXAMPLE Atmospheric corrosion of a given metal or alloy.
[SOURCE: ISO 9223:2012, 3.1, modified — An example has been added.]
4 Symbols and abbreviated terms
IC indoor corrosivity

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
5 Classification of corrosivity
5.1 General

The corrosivity of indoor atmospheres can be classified either by a determination of the corrosion attack

on standard specimens of selected standard metals as given in Clause 6 or, where this is not possible, by

an estimation of corrosivity based on the knowledge of humidity, temperature and pollution conditions

as described in Clause 7 and Annexes B, C and D.
2 © ISO 2020 – All rights reserved
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)

Estimation of corrosivity as described in 7.2 and Annexes C and D can lead to wrong conclusions.

Therefore, the determination of corrosivity by the 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 five 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. Preferably,

this month should represent the most corrosive period of the year.

Metals complement each other in the classification of indoor corrosivity for a given environment.

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 series deals with indoor air measurements describing the sampling strategy, including

the conditions to be observed for particular substances or groups of substances, such as the dependence

of indoor air pollution concentrations on atmospheric humidity or temperature or other effects.

ISO 16000-1:2004, Table A.1, summarizes the most important types of indoor environment and gives

examples of the sources that can be encountered in them. The list is not, of course, fully comprehensive

because of the large number of possibilities. ISO 16000-1:2004, Table B.1, shows the sources of indoor

air pollutants and the most important substances emitted. ISO 16000-1:2004, Table C.1, lists substances

frequently detected and their possible sources. The ISO 16000 series does not cover all indoor air

pollutants significant for indoor atmospheric corrosivity.

Methods for the characterization and measurement of environmental parameters of indoor atmospheres

are given in ISO 11844-3.

This method of corrosivity estimation is, in many cases, oversimplified and can give misleading results.

An estimation of corrosivity is based on:
— climatic influences (outdoor situation including pollution);
© ISO 2020 – All rights reserved 3
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
— indoor microclimate influences;
— indoor gaseous and particle pollution.

The corrosivity of an indoor atmosphere increases with higher humidity and depends on the type and

level of pollution.

Important characteristics are frequency of variation of relative humidity (RH) and temperature (T) in

intervals, and frequency and time of condensation.

An indoor environment is rarely static, since the concentration of any substance can 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 can 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 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 can occur, e.g. 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, as shown by Formula (1):

I/O== (1)
C  
nv+
 
 
where
C is the indoor concentration of pollutant (in μg.m );
C is the outdoor concentration of pollutant (in μg.m );
n is the air exchange rate (in h );
v is the deposition velocity (in m.h );
A is the inside surface area of room (in m );
V is the volume of room (in m ).

The typical I/O ratio of sulfur dioxide is approximately 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 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

propionic acid (CH CH COOH) can have a significant influence on indoor corrosivity. Carboxylic acids

3 2

in the atmosphere can 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 can be the 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.
4 © ISO 2020 – All rights reserved
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)

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 The characterization of the environment summarized in a guideline (see Annex D) forms a basis

for indoor corrosivity estimation. A 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 the indoor

corrosion of metals.

7.2.3 The determination of indoor corrosivity categories is illustrated in Tables 2 and 3.

NOTE 1 The specification of standard specimens of carbon steel, zinc, copper, silver and lead, 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 (see Table 2)

are preferably used for higher indoor corrosivity categories. 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 document 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 in accordance with ISO 9223.

NOTE 5 The upper limit of corrosivity category IC 5 corresponds roughly to the upper limit of corrosivity

category C 2 in accordance with ISO 9223.
© ISO 2020 – All rights reserved 5
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
6 © ISO 2020 – All rights reserved

Table 2 — Classification of corrosivity of indoor atmospheres based on corrosion rate measurements by mass loss determination of

standard specimens
−2 −1
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
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
© ISO 2020 – All rights reserved 7

Table 3 — Classification of corrosivity of indoor atmospheres based on rate of mass increase measured with standard specimens

−2 −1
Rate of mass increase (r ) (mg.m . a )
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
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SIST EN ISO 11844-1:2020
ISO 11844-1:2020(E)
Annex A
(informative)
Relationship between ISO, IEC and ISA classification systems
ISO 9223, IEC 6
...

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