Vitreous and porcelain enamels - Glass-lined apparatus for process plants - Part 1: Quality requirements for apparatus, components, appliances and accessories (ISO 28721-1:2019)

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 actions to be taken to repair defects. It is also applicable to glass-lined pumps, pump components and fittings. It does not apply to glass-lined flanged steel pipes or glass-lined flanged steel fittings. The test methods specified cover checking the enamel, the dimensional accuracy and the performance of apparatus and components. This document is applicable 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.

Emails und Emaillierungen - Emaillierte Apparate für verfahrenstechnische Anlagen - Teil 1: Qualitätsanforderungen für Apparate, Apparateteile, Einbau- und Zubehörteile (ISO 28721-1:2019)

Dieses Dokument legt die Qualitätsanforderungen an in verfahrenstechnischen Anlagen eingesetzten Apparaten, Apparateteilen sowie Einbau- und Zubehörteilen aus emailliertem Stahl (einschließlich teilkristallisierten Emailschichten) und Stahlguss fest. Es legt die Qualitätsanforderungen und die beim Hersteller durchzuführenden Prüfungen und die für die Ausbesserung von Emaildefekten erforderlichen Maßnahmen fest.
Es gilt auch für emaillierte Pumpen, Pumpenteile und Armaturen.
Es gilt nicht für Flansch-Rohre und Flansch-Formstücke aus Stahl mit Emaillierung.
ANMERKUNG 1   Festlegungen für Flansch-Rohre und Flansch-Formstücke aus Stahl mit Emaillierung sind in ISO 28721 4  gegeben.
Die festgelegten Prüfverfahren dienen zur Überprüfung des Emails, der Maßhaltigkeit und der Funktionsweise der Apparate und Bauteile.
Dieses Dokument gilt für neue und gebrauchte reemaillierte Apparate und Bauteile.
Es legt keine Anforderungen an die chemischen und physikalischen Eigenschaften des Emails fest.
ANMERKUNG 2 Im Anhang A sind Beispiele für Prüfberichte angegeben.

Émaux vitrifiés - Appareils émaillés pour les installations industrielles - Partie 1: Exigences de qualité relatives aux appareillages, composants, appareils et accessoires (ISO 28721-1:2019)

Le présent document spécifie les exigences de qualité relatives aux appareillages, composants, appareils et accessoires en acier émaillé (y compris les revêtements en émail semi-cristallisé) et en acier moulé émaillé utilisés dans des installations industrielles. Il spécifie les exigences de qualité et les essais devant être effectués par le fabricant, ainsi que les actions nécessaires pour la réparation des défauts.
Il est également applicable aux pompes, composants de pompes et accessoires émaillés.
Il ne s'applique pas aux tuyaux ou raccords à brides en acier émaillé.
NOTE 1 Des dispositions relatives aux tuyaux et raccords à brides en acier émaillé figurent dans l'ISO 28721-4.
Les méthodes d'essai indiquées couvrent la vérification de l'émail, l'exactitude dimensionnelle et la performance des appareils et des composants.
Le présent document est applicable aux nouveaux appareils et composants ainsi qu'aux produits utilisés et réémaillés.
Il ne contient aucune exigence concernant les propriétés chimiques ou physiques des émaux vitrifiés.
NOTE 2 Des exemples de rapports d'essai figurent à l'Annexe A.

Steklasti in keramični emajli - Emajlirane naprave za procesno opremo - 1. del: Zahteve za kakovost naprav, sestavnih delov, aparatov in pribora (ISO 28721-1:2019)

Ta dokument določa zahteve za kakovost naprav, sestavnih delov, aparatov in pribora emajliranega jekla (vključno z delno kristaliziranimi emajliranimi prevlekami) in emajliranih jeklenih ulitkov, ki se uporabljajo za procesno opremo. Določa zahteve glede kakovosti in preskuse, ki jih izvede proizvajalec, kot tudi ukrepe, ki jih je treba izvesti za popravilo napak. Uporablja se tudi za emajlirane črpalke, sestavne dele črpalk in armature. Ne uporablja se za emajlirane jeklene cevi s prirobnico ali emajlirane jeklene armature s prirobnico. Navedene preskusne metode zajemajo preverjanje emajla, točnosti dimenzij ter delovanja naprav in sestavnih delov. Ta dokument se uporablja za nove naprave in sestavne dele ter uporabljene elemente, ki so bili znova emajlirani. Ne vsebuje zahtev v zvezi s kemijskimi ali fizikalnimi lastnostmi steklastih in porcelanastih emajlov.

General Information

Status
Published
Public Enquiry End Date
04-Nov-2018
Publication Date
06-Nov-2019
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
23-Oct-2019
Due Date
28-Dec-2019
Completion Date
07-Nov-2019

RELATIONS

Buy Standard

Standard
SIST EN ISO 28721-1:2019
English language
25 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN ISO 28721-1:2019
01-december-2019
Nadomešča:
SIST EN ISO 28721-1:2011
Steklasti in keramični emajli - Emajlirane naprave za procesno opremo - 1. del:
Zahteve za kakovost naprav, sestavnih delov, aparatov in pribora (ISO 28721-
1:2019)

Vitreous and porcelain enamels - Glass-lined apparatus for process plants - Part 1:

Quality requirements for apparatus, components, appliances and accessories (ISO
28721-1:2019)

Emails und Emaillierungen - Emaillierte Apparate für verfahrenstechnische Anlagen - Teil

1: Qualitätsanforderungen für Apparate, Apparateteile, Einbau- und Zubehörteile (ISO

28721-1:2019)

Émaux vitrifiés - Appareils émaillés pour les installations industrielles - Partie 1:

Exigences de qualité relatives aux appareillages, composants, appareils et accessoires

(ISO 28721-1:2019)
Ta slovenski standard je istoveten z: EN ISO 28721-1:2019
ICS:
25.220.50 Emajlne prevleke Enamels
SIST EN ISO 28721-1:2019 en

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

---------------------- Page: 1 ----------------------
SIST EN ISO 28721-1:2019
---------------------- Page: 2 ----------------------
SIST EN ISO 28721-1:2019
EN ISO 28721-1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 25.220.50 Supersedes EN ISO 28721-1:2011
English Version
Vitreous and porcelain enamels - Glass-lined apparatus for
process plants - Part 1: Quality requirements for
apparatus, components, appliances and accessories (ISO
28721-1:2019)

Émaux vitrifiés - Appareils émaillés pour les Emails und Emaillierungen - Emaillierte Apparate für

installations industrielles - Partie 1: Exigences de verfahrenstechnische Anlagen - Teil 1:

qualité relatives aux appareillages, composants, Qualitätsanforderungen für Apparate, Apparateteile,

appareils et accessoires (ISO 28721-1:2019) Einbau- und Zubehörteile (ISO 28721-1:2019)

This European Standard was approved by CEN on 15 September 2019.

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

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 28721-1:2019 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 28721-1:2019
EN ISO 28721-1:2019 (E)
Contents Page

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

---------------------- Page: 4 ----------------------
SIST EN ISO 28721-1:2019
EN ISO 28721-1:2019 (E)
European foreword

This document (EN ISO 28721-1:2019) has been prepared by Technical Committee ISO/TC 107

"Metallic and other inorganic coatings" 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 April 2020, and conflicting national standards shall be

withdrawn at the latest by April 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 28721-1:2011.

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 28721-1:2019 has been approved by CEN as EN ISO 28721-1:2019 without any

modification.
---------------------- Page: 5 ----------------------
SIST EN ISO 28721-1:2019
---------------------- Page: 6 ----------------------
SIST EN ISO 28721-1:2019
INTERNATIONAL ISO
STANDARD 28721-1
Second edition
2019-09
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
Reference number
ISO 28721-1:2019(E)
ISO 2019
---------------------- Page: 7 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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 2019 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(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 ................................................................................................................................................................................................. 7

7.1 Repairing with plugs .......................................................................................................................................................................... 7

7.2 Removing impurities ......................................................................................................................................................................... 9

8 Test report ................................................................................................................................................................................................................... 9

9 Packaging and transportation .............................................................................................................................................................10

10 Inspection at delivery ...................................................................................................................................................................................10

Annex A (informative) Examples of test reports ...................................................................................................................................11

Bibliography .............................................................................................................................................................................................................................18

© ISO 2019 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(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 107, Metallic and other inorganic coatings.

This second edition cancels and replaces the first edition (ISO 28721-1:2008), which has been technically

revised. The main changes compared with the previous edition are as follows:
— the normative references have been updated;
— the subclause for “High-voltage test” (5.3) has been revised;

— the 7 kV test voltage for conductive or dissipative enamel according to 5.3 has been added to

Clause 10.
A list of all parts in the ISO 28721 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 2019 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 28721-1:2019
INTERNATIONAL STANDARD ISO 28721-1:2019(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 actions to be taken to repair defects.
It is also applicable to glass-lined pumps, pump components and fittings.

It does not apply 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

ISO 28721-4.

The test methods specified cover checking the enamel, the dimensional accuracy and the performance

of apparatus and components.

This document is applicable 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 2746, Vitreous and porcelain enamels — High voltage test

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 19496-1, Vitreous and porcelain enamels — Terminology — Part 1: Terms and definitions

© ISO 2019 – All rights reserved 1
---------------------- Page: 11 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(E)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 19496-1 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/
4 Requirements
4.1 General

If the requirements given in this document are to be applied to glass-lined apparatus and components,

this shall be stated as follows when ordering: “Manufactured in accordance with ISO 28721-1.”.

Requirements differing from those stated in this document 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 5.2). Typical defects are described in ISO 28721-5.

4.4.2 Defects unacceptable in the finished product

Defects unacceptable in the finished product are those that would render a component unusable. Such

defects are typically as follows:
a) defects which cannot be repaired by the means described in Clause 7, such as:
1) defects extending over an area with a diameter > 8 mm;
2) defects on inaccessible spots;
3) defects concerning vessels and columns as described in 4.4.4;
b) collapsed lines in the cover coat;
c) bubble lines, i.e. fused-in bubbles arranged in a distinct line;
2 © ISO 2019 – All rights reserved
---------------------- Page: 12 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(E)

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, for example, spot-like discolorations);

h) cracks detectable by, for example, a statiflux test;

i) spots with a diameter > 30 mm caused by grinding and polishing during the removal of impurities

(see also 4.4.3 and 7.2).
4.4.3 Repairable defects

Repairable defects are imperfections in the enamel coating that 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 5.3;

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 4.4.3 a) and 4.4.3 b) shall be repaired as described in 7.1.

Specifications regarding defects in various types of apparatus and components are given in 4.4.4 to 4.4.6.

Table 1 — Maximum permissible number of plugged enamel defects in vessels
Maximum permissible number of defects
Agitator vessels
Nominal volume
Type AE
Other vessels
Types BE
Lower part of
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
Assembly covers shall be delivered without any plugs.
© ISO 2019 – All rights reserved 3
---------------------- Page: 13 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(E)
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
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

Tables 1 and 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 7.1).
4.4.6 Fittings and pump components
Fittings and pump components shall not be repaired by plugging (see 7.1).
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 5.7.1 and 5.7.2) shall be agreed upon

between the interested parties.

NOTE Examples of tolerances for vessels other than agitator vessels, agitator vessels and columns are given

in DIN 28005-2, DIN 28006-2 and DIN 28007-2, respectively. DIN 28159 gives tolerances for 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.
4 © ISO 2019 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(E)

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 document 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.
© ISO 2019 – All rights reserved 5
---------------------- Page: 15 ----------------------
SIST EN ISO 28721-1:2019
ISO 28721-1:2019(E)
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 surfa
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.