SIST EN ISO 28706-5:2012
(Main)Vitreous and porcelain enamels - Determination of resistance to chemical corrosion - Part 5: Determination of resistance to chemical corrosion in closed systems (ISO 28706-5:2010)
Vitreous and porcelain enamels - Determination of resistance to chemical corrosion - Part 5: Determination of resistance to chemical corrosion in closed systems (ISO 28706-5:2010)
ISO 28706-5:2008 specifies a test method for the determination of the resistance of vitreous and porcelain enamelled articles to attack in closed systems by acid, neutral and alkaline liquids, as well as by actual process mixes.
It applies primarily to the testing of enamels designed for use in chemical processes.
Emails und Emaillierungen - Bestimmung der Beständigkeit gegen chemische Korrosion - Teil 5: Bestimmung der Beständigkeit gegen chemische Korrosion in geschlossenen Systemen (ISO 28706-5:2010)
Dieser Teil von ISO 28706 legt ein Prüfverfahren zur Bestimmung der Beständigkeit von emaillierten Gegenständen gegen den Angriff sowohl saurer, neutraler und alkalischer Flüssigkeiten als auch von Stoffgemischen aus dem betrieblichen Einsatz in geschlossenen Systemen fest.
Diese Norm gilt in erster Linie für die Prüfung von Emails und Emaillierungen, die für die Anwendung in der chemischen Verfahrenstechnik ausgelegt sind.
Emaux vitrifiés - Détermination de la résistance à la corrosion chimique - Partie 5: Détermination de la résistance à la corrosion chimique en milieux fermés (ISO 28706-5:2010)
L'ISO 28706-5:2010 spécifie une méthode d'essai permettant de déterminer la résistance des articles en émaux vitrifiés à l'attaque, en milieux fermés, des liquides acides, neutres et alcalins, ainsi que des mélanges impliqués dans les procédés réels.
Elle s'applique principalement aux essais des émaux conçus pour une utilisation dans les procédés chimiques.
Steklasti in porcelanski emajli - Ugotavljanje odpornosti proti kemični koroziji - 5. del: Ugotavljanje odpornosti proti kemični koroziji v zaprtih sistemih (ISO 28706-5:2010)
Ta del ISO 28706 opisuje preskusno metodo za ugotavljanje odpornosti steklastih in porcelanskih emajliranih predmetov v zaprtem sistemu proti napadu s kislimi, nevtralnimi in alkalnimi tekočinami ter dejanskimi procesnimi mešanicami. Velja predvsem za preskušanje emajlov za uporabo pri kemijskih procesih.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 28706-5:2012
01-januar-2012
1DGRPHãþD
SIST EN 14483-5:2004
6WHNODVWLLQSRUFHODQVNLHPDMOL8JRWDYOMDQMHRGSRUQRVWLSURWLNHPLþQLNRUR]LML
GHO 8JRWDYOMDQMHRGSRUQRVWLSURWLNHPLþQLNRUR]LMLY]DSUWLKVLVWHPLK ,62
Vitreous and porcelain enamels - Determination of resistance to chemical corrosion -
Part 5: Determination of resistance to chemical corrosion in closed systems (ISO 28706-
5:2010)
Emails und Emaillierungen - Bestimmung der Beständigkeit gegen chemische Korrosion
- Teil 5: Bestimmung der Beständigkeit gegen chemische Korrosion in geschlossenen
Systemen (ISO 28706-5:2010)
Emaux vitrifiés - Détermination de la résistance à la corrosion chimique - Partie 5:
Détermination de la résistance à la corrosion chimique en milieux fermés (ISO 28706-
5:2010)
Ta slovenski standard je istoveten z: EN ISO 28706-5:2011
ICS:
25.220.50 Emajlne prevleke Enamels
SIST EN ISO 28706-5:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 28706-5:2012
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SIST EN ISO 28706-5:2012
EUROPEAN STANDARD
EN ISO 28706-5
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2011
ICS 25.220.50 Supersedes EN 14483-5:2004
English Version
Vitreous and porcelain enamels - Determination of resistance to
chemical corrosion - Part 5: Determination of resistance to
chemical corrosion in closed systems (ISO 28706-5:2010)
Emaux vitrifiés - Détermination de la résistance à la Emails und Emaillierungen - Bestimmung der Beständigkeit
corrosion chimique - Partie 5: Détermination de la gegen chemische Korrosion - Teil 5: Bestimmung der
résistance à la corrosion chimique en milieux fermés (ISO Beständigkeit gegen chemische Korrosion in
28706-5:2010) geschlossenen Systemen (ISO 28706-5:2010)
This European Standard was approved by CEN on 17 June 2011.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 28706-5:2011: E
worldwide for CEN national Members.
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SIST EN ISO 28706-5:2012
EN ISO 28706-5:2011 (E)
Contents Page
Foreword .3
2
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SIST EN ISO 28706-5:2012
EN ISO 28706-5:2011 (E)
Foreword
The text of ISO 28706-5:2010 has been prepared by Technical Committee ISO/TC 107 “Metallic and other
inorganic coatings” of the International Organization for Standardization (ISO) and has been taken over as EN
ISO 28706-5:2011 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” 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 January 2012, and conflicting national standards shall be withdrawn at
the latest by January 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 14483-5:2004.
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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 28706-5:2010 has been approved by CEN as a EN ISO 28706-5:2011 without any
modification.
3
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SIST EN ISO 28706-5:2012
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SIST EN ISO 28706-5:2012
INTERNATIONAL ISO
STANDARD 28706-5
Second edition
2010-10-01
Vitreous and porcelain enamels —
Determination of resistance to chemical
corrosion —
Part 5:
Determination of resistance to chemical
corrosion in closed systems
Émaux vitrifiés — Détermination de la résistance à la corrosion
chimique —
Partie 5: Détermination de la résistance à la corrosion chimique
en milieux fermés
Reference number
ISO 28706-5:2010(E)
©
ISO 2010
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SIST EN ISO 28706-5:2012
ISO 28706-5:2010(E)
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ii © ISO 2010 – All rights reserved
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SIST EN ISO 28706-5:2012
ISO 28706-5:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Principle.1
4 Apparatus.2
5 Test specimens.3
6 Procedure.3
7 Expression of results.4
8 Autoclave test with hydrochloric acid.5
9 Test with hot sodium hydroxide solution .6
10 Tests with simulated solutions .7
11 Tests with process fluids.7
Annex A (informative) Explanatory notes.9
Bibliography.11
© ISO 2010 – All rights reserved iii
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SIST EN ISO 28706-5:2012
ISO 28706-5:2010(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 28706-5 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings.
This second edition cancels and replaces the first edition (ISO 28706-5:2008), of which it constitutes a
technical revision.
ISO 28706 consists of the following parts, under the general title Vitreous and porcelain enamels —
Determination of resistance to chemical corrosion:
⎯ Part 1: Determination of resistance to chemical corrosion by acids at room temperature
⎯ Part 2: Determination of resistance to chemical corrosion by boiling acids, boiling neutral liquids and/or
their vapours
⎯ Part 3: Determination of resistance to chemical corrosion by alkaline liquids using a hexagonal vessel
⎯ Part 4: Determination of resistance to chemical corrosion by alkaline liquids using a cylindrical vessel
⎯ Part 5: Determination of resistance to chemical corrosion in closed systems
iv © ISO 2010 – All rights reserved
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SIST EN ISO 28706-5:2012
ISO 28706-5:2010(E)
Introduction
Corrosion of vitreous and porcelain enamels by aqueous solutions is a dissolution process. The main
component of the enamel, silicon dioxide (SiO ), forms a three-dimensional silica network. After hydrolysis, it
2
decomposes and forms silicic acid or silicates. These are released into the attacking medium. Other
components, mainly metal oxides, are hydrolysed as well and form the corresponding hydrated metal ions or
hydroxides. All corrosion products are more or less soluble in the attacking medium. The whole process
results in a loss in mass per unit area.
For some aqueous solutions, the attack on the enamel proceeds linearly during the corrosion time; for other
aqueous solutions, the attack on the enamel proceeds in a logarithmic manner during the corrosion time. Only
2
for the first series of solutions can a scientifically exact rate of loss in mass per unit area (g/m ), as well as a
corrosion rate (mm/year), be calculated.
The most important parameters influencing aqueous corrosion of the enamel are the enamel quality, the
temperature and the pH value. Inhibition effects resulting from the limited solubility of silica can also contribute.
The following list describes different types of enamel attack for different corrosion conditions.
a) In aqueous alkali solutions like 0,1 mol/l NaOH (see Clause 9 of ISO 28706-4:2008) the silica network of
the enamel is considerably attacked at 80 °C. Silicates and most of the other hydrolysed components are
soluble in the alkali. Attack proceeds linearly during regular test times. Therefore, test results are
expressed in terms of a rate of loss in mass per unit area (mass loss per unit area and time) and a
corrosion rate (millimetres per year).
b) At room temperature, in weak aqueous acids like citric acid (see Clause 9 of ISO 28706-1:2008) or also in
stronger acids like sulfuric acid (see Clause 10 of ISO 28706-1:2008), there is only minor attack on the
silica network of the enamel. Other constituents are leached to some extent from the surface. Highly
resistant enamels will show no visual change after exposure. On less resistant enamels, some staining or
surface roughening will occur.
c) In boiling aqueous acids (see ISO 28706-2), the silica network of the enamel is being attacked, and silica
as well as the other enamel components are released into solution. However, the solubility of silica in
acids is low. Soon, the attacking solutions will become saturated with dissolved silica and will then only
leach the surface. The acid attack is inhibited and the rate of corrosion drops markedly.
NOTE The glass test equipment also releases silica by acid attack and contributes to the inhibition of the
corrosion.
Inhibition is effectively prevented in vapour phase tests. The condensate formed on the test specimen is
free of any dissolved enamel constituents.
Examples of enamel corrosion proceeding in a logarithmic manner [see 1)] and linearly [see 2)] are as
follows.
1) Boiling citric acid (see Clause 10 of ISO 28706-2:2008) and boiling 30 % sulfuric acid (see
Clause 11 of ISO 28706-2:2008)
Since only minute amounts of these acids are found in their vapours, the test is restricted to the liquid
phase. The attack is influenced by inhibition effects, and corrosion depends on the time of exposure.
Therefore, test results are expressed in terms of loss in mass per unit area; no rate of loss in mass
per unit area is calculated.
© ISO 2010 – All rights reserved v
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SIST EN ISO 28706-5:2012
ISO 28706-5:2010(E)
2) Boiling 20 % hydrochloric acid (see Clause 12 of ISO 28706-2:2008)
Since this is an azeotropic boiling acid, its concentration in the liquid and the vapour phase are
identical, and liquid phase testing need not be performed. Vigorous boiling supplies an uninhibited
condensate, and the attack proceeds linearly with time of exposure. Therefore, test results are only
expressed in terms of rate of loss in mass per unit area (mass loss per unit area and time) and the
corrosion rate (millimetres per year).
d) At high temperatures, with tests in the liquid phase under autoclave conditions (see ISO 28706-5),
aqueous acid attack is severe. To avoid inhibition, the test time is restricted to 24 h and the ratio of
attacking acid to attacked enamel surface is chosen so that it is comparatively high (similar to that in a
chemical-reaction vessel). In addition, only low-silica water is used for the preparation of test solutions.
Under these conditions, attack will proceed linearly with time of exposure. Therefore, test results with
20 % hydrochloric acid (see Clause 8 of ISO 28706-5:2010), simulated test solutions (see Clause 10 of
ISO 28706-5:2010) or process fluids (see Clause 11 of ISO 28706-5:2010) are also expressed in terms of
a rate of loss in mass per unit area (loss in mass per unit area and time).
e) In boiling water (see Clause 13 of ISO 28706-2:2008), the silica network is fairly stable. The enamel
surface is leached and silica is dissolved only to a small extent. This type of attack is clearly represented
by the vapour phase attack. In the liquid phase, some inhibition can be observed with highly resistant
enamels. However, if the vitreous and porcelain enamel being tested is weak, leached alkali from the
vitreous and porcelain enamel can raise pH values to alkaline levels, thus increasing the attack by the
liquid phase. Both liquid and vapour phase testing can give valuable information.
f) Since the attack may or may not be linear, the results are expressed only in terms of loss in mass per unit
area, and the test time should be indicated.
g) For standard detergent solution (see Clause 9 of ISO 28706-3:2008), it will not be certain whether the
linear part of the corrosion curve will be reached during testing for 24 h or 168 h. Calculation of the
corrosion rate is therefore not included in the test report.
h) For other acids (see Clause 14 of ISO 28706-2:2008) and other alkaline solutions (see Clause 10 of
ISO 28706-3:2008 and Clause 10 of ISO 28706-4:2008), it will also not be known if a linear corrosion rate
will be reached during the test period. Calculation of the corrosion rate is therefore not included in the test
reports of those parts of this International Standard.
For vitreous enamels fired at temperatures below 700 °C, the test parameters (media, temperatures and
times) of this part of ISO 28706 are not appropriate. For such enamels, for example aluminium enamels, other
media, temperatures and/or times should be used. This can be done following the procedures described in the
clauses for “Other test solutions” in Parts 1, 2, 3 and 4 of this International Standard.
vi © ISO 2010 – All rights reserved
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SIST EN ISO 28706-5:2012
INTERNATIONAL STANDARD ISO 28706-5:2010(E)
Vitreous and porcelain enamels — Determination of resistance
to chemical corrosion —
Part 5:
Determination of resistance to chemical corrosion in closed
systems
WARNING — This part of ISO 28706 calls for the use of substances and/or procedures that may be
injurious to health if adequate safety measures are not taken. This part of ISO 28706 does not address
any health hazards, safety or environmental matters associated with its use. It is the responsibility of
the user of this part of ISO 28706 to establish appropriate health, safety and environmentally
acceptable practices and take suitable actions for any national and international regulations.
Compliance with this part of ISO 28706 does not in itself confer immunity from legal obligations.
1 Scope
This part of ISO 28706 specifies a test method for the determination of the resistance of vitreous- and
porcelain-enamelled articles to attack in closed systems by acid, neutral and alkaline liquids, as well as by
actual process mixes.
It applies primarily to the testing of enamels designed for use in chemical processes.
2 Normative references
The following referenced documents are indispensable for the application 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 649-1, Laboratory glassware — Density hydrometers for general purposes — Part 1: Specification
ISO 3696, Water for analytical laboratory use — Specification and test methods
3 Principle
Enamelled test specimens are exposed to attack by a liquid corrosive at temperatures above the normal
boiling point, under defined autoclave conditions.
The loss in mass is determined and used to calculate the rate of loss in mass per unit a
...
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