SIST EN ISO 28721-1:2019

SLOVENSKI STANDARD
oSIST prEN ISO 28721-1:2018
01-november-2018
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Vitreous and porcelain enamels - Glass-lined apparatus for process plants - Part 1:
Quality requirements for apparatus, components, appliances and accessories (ISO/DIS
28721-1:2018)
Emails und Emaillierungen - Emaillierte Apparate für verfahrenstechnische Anlagen - Teil
1: Qualitätsanforderungen für Apparate, Apparateteile, Einbau- und Zubehörteile
(ISO/DIS 28721-1:2018)
Émaux vitrifiés - Appareils émaillés pour les installations industrielles - Partie 1:
Exigences de qualité relatives aux appareillages, composants, appareils et accessoires
(ISO/DIS 28721-1:2018)
Ta slovenski standard je istoveten z: prEN ISO 28721-1
ICS:
25.220.50 Emajlne prevleke Enamels
oSIST prEN ISO 28721-1:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 28721-1:2018

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oSIST prEN ISO 28721-1:2018
DRAFT INTERNATIONAL STANDARD
ISO/DIS 28721-1
ISO/TC 107 Secretariat: KATS
Voting begins on: Voting terminates on:
2018-07-16 2018-10-08
Vitreous and porcelain enamels — Glass-lined apparatus
for process plants —
Part 1:
Quality requirements for apparatus, components,
appliances and accessories
Émaux vitrifiés — Appareils émaillés pour les installations industrielles —
Partie 1: Exigences de qualité relatives aux appareillages, composants, appareils et accessoires
ICS: 25.220.50
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
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 28721-1:2018(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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oSIST prEN ISO 28721-1:2018
ISO/DIS 28721-1:2018(E)

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
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
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Email: copyright@iso.org
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Published in Switzerland
ii © ISO 2018 – All rights reserved

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oSIST prEN ISO 28721-1:2018
ISO/DIS 28721-1:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Requirements . 2
4.1 General . 2
4.2 Design and quality of enamel finish . 2
4.3 Surface . 2
4.4 Defects . 2
4.4.1 General. 2
4.4.2 Defects unacceptable in the finished product . 2
4.4.3 Repairable defects . 3
4.4.4 Vessels and columns . 4
4.4.5 Accessories . 4
4.4.6 Fittings and pump components . 4
4.5 Coating thickness . 4
4.6 General tolerances . 4
4.7 Finish . 4
5 Testing . 5
5.1 General . 5
5.2 Visual examination . 5
5.3 High-voltage test . 5
5.4 Testing for cracks . 5
5.5 Coating thickness measurement. 5
5.6 Measurement of dimensions . 6
5.7 Determination of the concentricity of agitators and pump rotors . 6
5.7.1 General. 6
5.7.2 Agitators . 6
5.7.3 Pump rotors . 6
5.8 Performance testing . 6
5.9 Completeness check . 7
6 Manufacturing stages and inspections . 7
7 Repairing defects . 8
7.1 Repairing with plugs . 8
7.2 Removing impurities . 9
8 Test report . 9
9 Packaging and transportation .10
10 Inspection at delivery .11
Annex A (informative) Examples of test reports .12
Bibliography .19
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oSIST prEN ISO 28721-1:2018
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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 on 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 the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical CommitteeISO/TC 107, Metallic and other inorganic coatings.
This second edition cancels and replaces the firstedition (28721-1:2008), which has been technically
revised.The main changes compared to the previous edition are as follows:
— Normative references updated;
— Revision of 6.3 " High-voltage test";
— Amendment in Clause 11 in order to ad the 7 kV test voltage according to 6.3;
— Editorial changes and update of bibliography.
A list of all parts in the ISO 28721 series can be found on the ISO website.
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oSIST prEN ISO 28721-1:2018
DRAFT INTERNATIONAL STANDARD ISO/DIS 28721-1:2018(E)
Vitreous and porcelain enamels — Glass-lined apparatus
for process plants —
Part 1:
Quality requirements for apparatus, components,
appliances and accessories
1 Scope
This document specifies the quality requirements for apparatus, components, appliances and
accessories of glass-lined steel (including semi-crystallized enamel coatings) and glass-lined steel
castings used for process plants. It specifies the quality requirements and the tests to be carried out by
the manufacturer as well as the action to be taken to repair defects.
It is also applicable to glass-lined pumps, pump components and fittings.
It is not applicable to glass-lined flanged steel pipes or glass-lined flanged steel fittings.
NOTE 1 Provisions for glass-lined flanged steel pipes and glass-lined flanged steel fittings are given in
[3]
ISO 28721-4 .
The test methods specified cover checking the enamel, the dimensional accuracy and the performance
of apparatus and components.
This document applies to new apparatus and components as well as used items that have been re-
enamelled.
It does not contain requirements regarding the chemical or physical properties of vitreous and
porcelain enamels.
NOTE 2 Examples of test reports are given in Annex A.
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 780, Packaging — Distribution packaging — Graphical symbols for handling and storage of packages
ISO 2178, Non-magnetic coatings on magnetic substrates — Measurement of coating thickness —
Magnetic method
ISO 28721-2, Vitreous and porcelain enamels — Glass-lined apparatus for process plants — Part 2:
Designation and specification of resistance to chemical attack and thermal shock
ISO 28721-3, Vitreous and porcelain enamels — Glass-lined apparatus for process plants — Part 3: Thermal
shock resistance
ISO 2746, Vitreous and porcelain enamels — High voltage test
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oSIST prEN ISO 28721-1:2018
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3 Terms and definitions
[1]
For the purposes of this document, the terms and definitions given in ISO 19496 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 http: //www .iso .org/obp
4 Requirements
4.1 General
If the requirements given in this part of ISO 28721 are to be applied to glass-lined apparatus and
components, this shall be stated as follows when ordering:
Prepared in accordance with ISO 28721-1.
Requirements differing from those stated in this part of ISO 28721 may be agreed upon between the
parties at the time of ordering.
4.2 Design and quality of enamel finish
The manufacturer shall be responsible for the appropriate design and construction.
The enamel quality (i.e. the type of enamel and, where relevant, the colour) shall be agreed upon
between the interested parties at the time of ordering.
The characteristic composition of individual enamel layers shall correspond to that of specimens
submitted for laboratory testing. The quality of the enamel shall meet the requirements specified in
ISO 28721-2 and ISO 28721-3.
4.3 Surface
The enamel coating shall have a uniform, smooth, fully-fused surface free from impurities.
4.4 Defects
4.4.1 General
Defects shall be examined visually (see 6.2).
4.4.2 Defects unacceptable in the finished product
Defects unacceptable in the finished product are those which would render a component unusable. Such
defects are typically as follows:
a) defects which cannot be repaired by the means described in Clause 8, such as:
— defects extending over an area with a diameter > 8 mm,
— defects on inaccessible spots,
— defects concerning vessels and columns as described in 5.4.4;
b) collapsed lines in the cover coat;
c) bubble lines, i.e. fused-in bubbles arranged in a distinct line;
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oSIST prEN ISO 28721-1:2018
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d) fused strain lines (recognizable as lines with colours different from that of the surrounding
enamel);
e) areas not properly fused (a rough surface similar to a sandblasted one);
f) devitrified areas in vitreous enamel or over crystallized areas in semi-crystallized enamel
(recognizable as a dull or a rough surface);
g) pull-through of ground coat (recognizable as e.g. spot-like discolorations);
h) cracks detectable by e.g. a statiflux test;
i) spots with a diameter > 30 mm caused by grinding and polishing during the removal of impurities
(see also 5.4.3 and 8.2).
4.4.3 Repairable defects
Repairable defects are imperfections in the enamel coating which allow, under certain circumstances
(see below), further use of glass-lined equipment after repair. Common repairable defects are:
a) depressions with a depth exceeding 25 % of the coating thickness;
b) blisters, such as circular holes in the coating exposing the ground coat;
c) areas with weak spots or defects detectable by high-voltage testing in accordance with 6.3;
d) impurities in the enamel coating.
Isolated impurities, such as fire clay particles, shall be removed. Dust-like impurities on the surface
may be accepted. Scale fused into the surface shall be removed where it extends parallel to the surface
over a distance of more than 3 mm and/or is not a flat particle or is not fused parallel to the surface.
The maximum permissible number of defects repaired by plugging shall be as given in Tables 1 and 2.
Further requirements, such as the maximum level of pores or use without plugging, shall be agreed
upon between the interested parties at the time of ordering.
Defects as defined in 5.4.3 a) and 5.4.3 b) shall be repaired as described in 8.1.
Specifications regarding defects in various types of apparatus and components are given in 5.4.4 to 5.4.6.
Table 1 — Maximum permissible number of plugged enamel defects in vessels
Maximum permissible number of defects
Agitator vessels
Nominal volume
Type AE
3
Other vessels
m
Types BE
Lower part of
a
and CE
Main cover
vessel
up to 4 0 0 0 0
over 4 to 10 1 1 1 1
over 10 to 20 — — 2 3
over 20 to 32 — — 3 4
over 32 to 40 — — 4 5
over 40 to 80 — — — 6
over 80 — — — 7
a
Assembly covers shall be delivered without any plugs.
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oSIST prEN ISO 28721-1:2018
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Table 2 — Maximum permissible number of plugged enamel defects in columns
Maximum permissible number of defects for unit lengths
Nominal diameter of column
over 2 000 mm
up to 2 000 mm over 5 000 mm
mm
up to 5 000 mm
up to 600 0 0 0
over 600 to 1 200 0 1 2
over 1 200 1 2 3
4.4.4 Vessels and columns
Table 1 and Table 2 list the number of repairable defects to be covered with plugs. Exceptions apply in
the following cases:
a) outlet nozzles and agitator nozzles, including the complete neck area around the nozzle, shall not
be repaired by plugging (this also applies to other nozzles with a nominal diameter of 150 mm or
less, including the neck area which extends out 30 mm beyond the inner nozzle diameter);
b) convex and concave surfaces with a radius of 75 mm or less shall not be repaired by plugging;
c) seal areas (gasket bearing surfaces) shall not be repaired by plugging.
4.4.5 Accessories
Accessories such as agitators, baffles, thermo pipes, probes, inlet pipes, washers, manhole covers and
dip-pipes shall not be repaired by plugging (see 8.1).
4.4.6 Fittings and pump components
Fittings and pump components shall not be repaired by plugging (see 8.1).
4.5 Coating thickness
The thickness of enamel coatings on steel substrates shall range from 1,0 mm to 2,2 mm, with the
following exceptions:
a) maximum values may be exceeded by 0,2 mm on concave surfaces;
b) the enamel coating may be 0,2 mm thinner than the specified minimum value in limited areas and
on convex surfaces;
c) coatings on small parts with very small radii ⩽ 5 mm, such as valve stems or rotors of pumps, may
have a minimum thickness of 0,6 mm.
Any changes in thickness shall be smooth.
4.6 General tolerances
General tolerances and tests for the concentricity of agitators (see 6.7.1 and 6.7.2) shall be agreed upon
between the interested parties.
NOTE Examples of tolerances for vessels other than agitator vessels, agitator vessels and columns are given
[[4]] [[5]] [[6]] [[7]]
in DIN 28005-2 , DIN 28006-2 and DIN 28007-2 , respectively. DIN 28159 gives tolerances for
[[8]]
agitator ends and DIN 2873 gives permissible angular misalignments for flange surfaces.
4.7 Finish
Unless otherwise agreed, non-enamelled surfaces, except for those which are not to be coated, such as
fitting surfaces, shall be protected by a primer.
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oSIST prEN ISO 28721-1:2018
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Details shall be agreed upon between the interested parties at the time of ordering.
Corrosion protection of parts without a primer coating, e.g. connecting elements, shall be agreed upon
between the interested parties at the time of ordering.
5 Testing
5.1 General
Tests carried out in accordance with this part of ISO 28721 shall be conducted only by skilled personnel
and shall be documented.
NOTE Examples of test report formats are given in Annex A.
The surfaces to be tested shall be clean, dry, sufficiently illuminated and easily accessible.
The components tested and the test reports shall be marked to allow proper identification. It is at the
customer's discretion to have his/her own inspectors verify the test results by repeating the tests at
the manufacturing site as described below.
Details of testing shall be agreed upon between the interested parties at the time of ordering.
5.2 Visual examination
The surfaces of glass-lined apparatus and components shall be checked visually. Optical instruments,
such as magnifying glasses, may be used for closer examination.
5.3 High-voltage test
High-voltage tests shall be conducted in accordance with ISO 2746. When the enamelling of a component
is complete, the manufacturer shall run a high-voltage test at 20 kV.
For subsequent tests, a voltage of maximum 12 kV shall be used.
By customer request, and with the agreement of the manufacturer, particular areas may be re-checked
with a higher voltage. Totally glass-lined components shall be tested with pulsed DC voltage.
Exceptions apply in the following cases:
a) enamelled probes shall be tested with a DC voltage of 7 kV;
b) for components coated with conductive or dissipative enamel, the manufacturer shall run a high-
voltage test at 7 kV; they shall be appropriately marked by the manufacturer.
5.4 Testing for cracks
Areas where cracks are presumed to have formed shall be sprayed with electrostatically charged
talcum powder to make cracks more visible. Even fine cracks will then be clearly revealed.
5.5 Coating thickness measurement
Measurement of the coating thickness shall be carried out in accordance with ISO 2178, using a
measuring instrument accurate to 5 % of the actual value. The thickness shall be measured using
spot checks. Extra measurements shall, however, be taken at critical spots such as small radii, uneven
surfaces and localized increases in thickness.
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oSIST prEN ISO 28721-1:2018
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5.6 Measurement of dimensions
The following dimensions shall be measured and recorded:
a) the inside diameter and any out-of-roundness of the vessel;
b) the diameter and any out-of-roundness of the assembly flange and main flange;
c) any wavelike distortion of the sealing surfaces of the assembly flange and main flange;
d) the out-of-plane angle of the sealing surfaces of the nozzles;
e) the compensation thickness of the gaskets;
f) the distances between the support ring, the brackets and the legs and a reference plane in each case;
g) any variations in the distances between points on the support ring circumference, individual
brackets and individual legs and a reference plane in each case;
h) agreement of the support element dimensions (i.e. the thickness and outer diameter of the support
ring) with the drawing;
i) the ground clearance of the agitator;
j) agreement of the jacket nozzle dimensions with the drawing.
Additional measurements may be made at the discretion of the customer.
The manufacturer shall measure and document the actual dimensions. The forms included in Annex A
may be used for this purpose.
5.7 Determination of the concentricity of agitators and pump rotors
5.7.1 General
Details of the determination of the concentricity of impellers and pump rotors after assembly shall be
agreed upon between the interested parties.
[[9]]
NOTE A method for determining the concentricity of impellers and pump rotors is given in DIN 28161 .
5.7.2 Agitators
The maximum eccentricity of agitators that are supplied separately shall be documented; the
measurements shall be performed by the manufacturer after machining and with the impellers still in
the lathe.
5.7.3 Pump rotors
The concentricity of pump rotors shall be determined by the manufacturer and, if requested, the
manufacturer shall document the results.
5.8 Performance testing
The manufacturer shall check the performance of the glass-lined components after assembly. Particular
attention shall be paid to the proper performance of moving components (see also 6.7.1).
Further tests covering the performance of mechanical seals or test runs with power measurement may
be agreed upon between the interested parties at the time of ordering.
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oSIST prEN ISO 28721-1:2018
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5.9 Completeness check
A completeness check, including the outside coating, shall be carried out to ensure compliance with
the order.
6 Manufacturing stages and inspections
Inspections shall be conducted when the glass-lined components are at the manufacturing stages
shown in Table 3.
If the customer requests that the tests be carried out by his/her representative, the manufacturer shall
give sufficient notice of the times at which the components concerned will be at the manufacturing
stages at which they are to be inspected.
Table 3 — Stages at which testing is to be carried out
Tests in accordance with subclauses
4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9
Glass-lined
Concentricity
compo-nent
Test- Coating thick- Measure- Complete-ness
Visual exam- High-volt- of agitators Perfor-mance
ing for ness meas- -ment of check, including
in-ation age test and pump testing
cracks ure-ment dimen-sions outside coating
rotors
Agitator vessels
First test after enamelling, if possible prior to welding of
elements such as jacket or support structure
Measure
roundness and
dimensions
possibly altered
After installa-
by firing after —
tion
enamelling.
Second test after assembly, together
Measure other
—
with performance testing
dimensions
after assembly.
Compo-nent s Before delivery
and agitator or-
dered together
with the agita-
Agitators:
After installa-
tor vessel
After enamelling and machining after instal-
tion
lation
A c c e s s- or ie s
and agitators
Agitators:
ordered sepa-
after enam-
After enamelling and machining —
rately
elling and
machining
S
...