EN 60654-4:1997
(Main)Operating conditions for industrial-process measurement and control equipment - Part 4: Corrosive and erosive influences
Operating conditions for industrial-process measurement and control equipment - Part 4: Corrosive and erosive influences
Considers the corrosive and erosive industrial environment to which land-based and offshore industrial-process measurement and control systems or parts of systems may be exposed during operation, during periods when they are installed but inactive, during storage or transportation. Maintenance and repair conditions are not considered.
Einsatzbedingungen für Meß-, Steuer- und Regeleinrichtungen in der industriellen Prozeßtechnick - Teil 4: Korrosive und erosive Einflüsse
Conditions de fonctionnement pour les matériels de mesure et commande dans les processus industriels - Partie 4: Influences de la corrosion et de l'érosion
Prend en considération les conditions d'environnement propres à la corrosion et à l'érosion auxquelles les systèmes de mesure et de commande des processus industriels ou les constituants de ces systèmes, situés à terre ou sur des plates-fomres en mer, peuvent être exposés en cours de fonctionnement, au cours de périodes pendant lesqueles ils sont installés mais ne sont pas actifs, en cours de stockage ou en cours de transport. Les conditions d'entretien et de réparation ne sont pas traitées.
Operating conditions for industrial-process measurement and control equipment - Part 4: Corrosive and erosive influences (IEC 60654-4:1987)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-1998
Operating conditions for industrial-process measurement and control equipment -
Part 4: Corrosive and erosive influences (IEC 60654-4:1987)
Operating conditions for industrial-process measurement and control equipment -- Part
4: Corrosive and erosive influences
Einsatzbedingungen für Meß-, Steuer- und Regeleinrichtungen in der industriellen
Prozeßtechnick -- Teil 4: Korrosive und erosive Einflüsse
Conditions de fonctionnement pour les matériels de mesure et commande dans les
processus industriels -- Partie 4: Influences de la corrosion et de l'érosion
Ta slovenski standard je istoveten z: EN 60654-4:1997
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
NORME
CEI
INTERNATIONALE
IEC
654-4
INTERNATIONAL
Première édition
STANDARD
First edition
Conditions de fonctionnement pour les matériels
de mesure et commande dans les processus
industriels
Quatrième partie:
Influences de la corrosion et de l'érosion
Operating conditions for industrial-process
measurement and control equipment
Part 4:
Corrosive and erosive influences
© CEI 1987 Droits de reproduction réservés — Copyright - all rights reserved
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654-4 © I E C 1987 3
CONTENTS
Page
FOREWORD 5
PREFACE 5
Clause
1. Scope 7
2. Object 7
3. General 9
4. Non-solid substances 9
4.1 Definitions
5. Gases and vapours
5.1 Contamination effects
5.2 Inorganic chlorine compounds
5.3 Explanation of contaminant severity levels
6. Aerosols
7. Liquids . . .
8. Solid substances
8.1 Kind of industrial-process and location within that process
8.2 Nature of solid substances in the environment which could affect
the instruments
In combination with 8.3
8.4 Frequency of occurrence
8.5 Size
8.6 Concentration in mg/kg or g/kg of dry air
8.7 Velocity in m/s
8.8 Thermal conductivity
8.9 Electrical conductivity
8.10 Magnetic permeability 21
8.11 Example given to demonstrate the use of the questionnaire
9. Flora and fauna 23
APPENDIX A — Industrial contaminants 25
APPENDIX B — Methods of classification of reactive environments
654-4 0 I E C 1987 — 5—
INTERNATIONAL ELECTROTECHNICAL COMMISSION
OPERATING CONDITIONS FOR INDUSTRIAL-PROCESS
MEASUREMENT AND CONTROL EQUIPMENT
Part 4: Corrosive and erosive influences
FOREWORD
1) The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on which all
the National Committees having a special interest therein are represented, express, as nearly as possible, an international
consensus of opinion on the subjects dealt with.
2) They have the form of recommendations for international use and they are accepted by the National Committees in that
sense.
In order to promote international unification, the IEC expresses the wish that all National Committees should adopt
3)
the text of the IEC recommendation for their national rules in so far as national conditions will permit. Any divergence
between the IEC recommendation and the corresponding national rules should, as far as possible, be clearly indicated
in the latter.
PREFACE
This standard has been prepared by IEC Technical Committee No. 65: Industrial-process
measurement and control.
The text of this standard is based upon the following documents:
Six Months' Rule Report on Voting
65(CO)38 65(CO)41
Full information on the voting for the approval of this standard can be found in the Voting
Report indicated in the above table.
7 —
654-4 I E C 1987 ©
CONDITIONS FOR INDUSTRIAL-PROCESS
OPERATING
MEASUREMENT AND CONTROL EQUIPMENT
Part 4: Corrosive and erosive influences
1. Scope
Part 4 of the standard considers the corrosive and erosive industrial environment to which
land-based and off-shore, industrial-process measurement and control systems or parts of
systems may be exposed during operation, during periods when they are installed but inactive,
during storage or transportation. Maintenance and repair conditions are excluded from this
part.
The environmental in fluences considered in this part are limited to those which may directly
affect performance of process-measurement and control systems or parts of such systems.
Effects of the specific environmental conditions on personnel are not within the scope of this
part. The appropriate values of the physical or chemical parameters listed here as well as the
qualitative descriptions of the environment should be used to define local environments in
which equipment is expected to operate, be transported and stored. Only conditions as such
are considered; the resulting effects of these conditions on instrument performance are
specifically excluded.
Many environmental conditions listed in this part are difficult to classify so that a qualitative
description is used to characterize the environment.
Object
2.
The object of Part 4 of the standard is to provide users and suppliers of industrial-process
measurement and control systems and parts of such systems with a uniform listing and
classification of corrosive and erosive environmental conditions to which equipment may be
exposed in specified locations during operation, storage, handling and transportation. Condi-
tions for transportation are for equipment in suitable packages to prevent damage.
The listed environmental conditions are intended to serve as a basis for comprehensive
specifications.
One of the objects of this part is to minimize problems which might result from neglecting
considerations of specific operating conditions affecting performance of systems and parts of
systems.
An additional object of this part is to aid in the choice of specific limit values for use in the
development of evaluation specifications for industrial-process measurement and control
equipment.
654-4 © I E C 1987 9
3. General
Industrial-process measurement and control equipment is used all over the earth, thus being
exposed to the characteristic environmental conditions of fauna and flora of tropical, tempe-
rate and arctic climates, as well as deserts, jungles, mountains and the sea.
Superimposed on these basic environmental influences and in addition to the general level
of ambient pollution prevalent in industrialized areas where process control equipment and
systems are heavily utilized, it should be recognized that higher levels of contamination do
generally exist in the localized areas where the process control equipment is deployed, as
contaminants are introduced into the environment by the very process that is being controlled.
These higher levels of contamination can occur permanently or temporarily. In many cases
the effects on measurement and control equipment are proportional to the concentration,
temperature and the period of exposure, these effects being often increased by humidity. It
is however very difficult to describe an environment by specifying the concentration of the
contaminant against time. Therefore, the concept of the average value was used as a basis for
quantitatively classifying the chemically active substances. But it is recognized that special
damage may be caused by short-time high concentration (peak value) of corrosive contami-
nants, therefore the peak values as defined below have been incorporated in the classification.
In Appendix A is given a listing of industrial contaminants associated with various process
plants. It is a guide to highlight the specific contaminants introduced by industrial processes.
Atmospheric contamination to which systems and parts of systems may be exposed include
gases, vapours, liquids and solids. The effects of these contaminants can be various, such as
the corrosive effects from chemically active contaminants, erosive effects from sand blasting
and clogging by dusts.
The different kinds of contaminants can also be present in combinations whereby more
severe environmental conditions can arise such as high humidity combined with chlorine gas;
therefore, the ambient temperature and relative humidity should be specified.
It is practically impossible to classify all the different environments, due to the unlimited
number of possible combinations and associated large number of effects and severities.
It is recognized that the effects of gases, vapours and liquids are primarily corrosive while
solid contaminants may cause adverse erosive, corrosive, thermal or electromagnetic effects.
Therefore, Clauses 4, 5, 6 and 7 classify the corrosive effects of non-solid chemically active
substances. Clauses 8 and 9 are enumerations of other environmental effects on instrumenta-
tion in which solid active substances are listed and the effects of flora and fauna are briefly
mentioned.
4.
Non-solid substances
Non-solid substances are only chemically active. They are therefore classified according to
the average and peak value of their concentration.
654-4 © I E C 1987 — 11 —
4.1 Definitions
The following definitions are required to understand this part.
One-half hour mean value is defined as
/,
1 h
x dt
'/2 h
where x is the measured or expected contaminant concentration.
Peak value is the maximum measured or expected one-half hour mean value recognized over
a year.
Mean value is the arithmetic mean of a statistically sufficient number of measured or
expected one-half hour mean values.
Note. — A one hour mean value may be used where legal.
5. Gases and vapours
The classes in Table I recognize that average concentrations and peak values shall both be
considered to properly classify an environment. Peak values have been integrated on a '/2 hour
h
basis. Chemical agents (e.g. SO 2 or HF) may vary greatly in their reactivity rate over a '/2
period. Therefore, the relationship of peak value to average value may vary with each
contaminant. The classification of environment by category should be determined by the
highest class if average and peak values are not in the same category. An alternate method
of classification based on copper reactivity rates is shown in Appendix B.
5.1 Contamination effects
Each site may have different combinations and concentration levels of corrosive gaseous
contaminants. Performance degradation can occur rapidly or over many years, depending on
the particular concentration levels and combinations present at a site. The following para-
graphs describe how various contaminants contribute to equipment performance degradation.
5.2 Inorganic chlorine compounds 2 in Table I)
(expressed as C1
This group contains both strong oxidants (chlorine, chlorine dioxide) and compounds such
as hydrogen chloride, so reactivity will depend upon the specific gas composition. In the
presence of moisture, these gases generate chloride ions which react readily with copper, tin,
silver and iron alloys. These reactions are significant even when the gases are present at low
levels. These reactions are attenuated in dry atmospheres. At higher concentrations, many
elastomers and some plastics are oxidized by exposure to chlorinated gases. Particular care
shall be given to equipment which is exposed to atmospheres which contain chlorinated
contaminants. Sources of chloride ions, such as cleaning compounds and cooling tower
vapours, etc., should be considered when classifying.
654-4 © I E C 1987 — 13 —
5.2.1 Active sulphurs (expressed as H,S in Table I)
This group includes hydrogen sulphide, elemental sulphur and organic sulphur compounds
such as the mercaptans. When present at low levels, they rapidly attack copper, silver and iron
alloys. The presence of moisture and small amounts of inorganic chlorine compounds greatly
accelerates sulphide corrosion. Note, however, that attack still occurs in low relative humidity
environments. Active sulphurs rank alongside inorganic chlorides as the predominant cause
of atmospheric corrosion in the process industries.
5.2.2 (expressed as SO, in Table I)
Sulphur oxides
Oxidized forms of sulphur (SO 2, SO 3) are generated as combustion products of sulphur-
bearing fossil fuels. Low levels of sulphur oxides can passivate reactive metals and thus retard
corrosion. At higher levels they attack certain types of metals, elastomers and plastics. The
reactions with metals normally occur when these gases dissolve in water to form sulphurous
and sulphuric acid.
5.2.3 Nitrogen oxides (expressed as NO X in Table I)
NO X compounds (NO, NO„ N,O 4) are formed as combustion products of fossil fuels and
have a critical role in the formation of ozone in the atmosphere. They are also believed to have
a catalytic effect on corrosion of base metals by chlorides and sulphides. In the presence of
moisture, these gases form nitric acid which, in turn, attacks most common metals.
5.2.4 Hydrogen fluoride (expressed as HF in Table I)
This compound is a member of the halogen family and reacts like inorganic chloride
compounds.
5.2.5 Ammonia and derivatives (expressed as NH 3 in Table I)
Reduced forms of nitrogen (ammonia, amines, ammonium ions) occur mainly in fertilizer
plants, agricultural applications, and chemical plants. Copper and copper alloys are particu-
larly susceptible to corrosion in ammonia environments.
5.2.6 Photochemical species (expressed as 0 3 in Table I)
The atmosphere contains a wide variety of unstable, reac
...
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