SIST EN ISO 28765:2023

Vitreous and porcelain enamels - Design of bolted steel tanks for the storage or treatment of water or municipal or industrial effluents and sludges (ISO 28765:2022)

This document specifies the requirements for the design and use of vitreous enamel coated bolted cylindrical steel tanks for the storage or treatment of water or municipal or industrial effluents and sludges.
It is applicable to the design of the tank and any associated roof and gives guidance on the requirements for the design of the foundation.
It is applicable where:
a) the tank is cylindrical and is mounted on a load-bearing base substantially at or above ground level;
b) the product of the tank diameter in metres and the wall height in metres lies within the range 5 to 500;
c) the tank diameter does not exceed 100 m and the total wall height does not exceed 50 m;
d) the stored material has the characteristics of a liquid, exerting a negligible frictional force on the tank wall; the stored material can be undergoing treatment as part of a municipal or industrial effluent treatment process;
e) the internal pressure in the headspace above the liquid does not exceed 50 kPa and the internal partial vacuum above the liquid does not exceed 10 kPa;
f) the walls of the tank are vertical;
g) the floor of the tank is substantially flat at its intersection with the wall; the floor of the tank can have a rise or fall built in to allow complete emptying of the tank contents, the slope of which does not exceed 1:100;
h) there is negligible inertial and impact load due to tank filling;
i) the minimum thickness of the tank shell is 1,5 mm;
j) the material used for the manufacture of the steel sheets is carbon steel (tanks constructed of sheets made from aluminium or stainless steel are outside the scope of this document);
k) the temperature of the tank wall during operation is within the range −50 °C to +100 °C under all operating conditions.
This document also gives details of procedures to be followed during installation on site and for inspection and maintenance of the installed tank.
It does not apply to chemical-reaction vessels.
It does not cover resistance to fire.

Emails und Emaillierungen - Gestaltung von verschraubten Stahlbehältern für die Speicherung oder Behandlung von Wasser oder kommunalen und industriellen Abwässern und Abwasserschlamm (ISO 28765:2022)

Dieses Dokument legt die Anforderungen an Gestaltung und Gebrauch von emailbeschichteten, verschraubten, zylindrischen Stahlbehältern für die Speicherung oder Behandlung von Wasser oder kommunalen oder industriellen Abwässern und Abwasserschlämmen fest.
Dieses Dokument ist anwendbar für die Gestaltung des Behälters und eines jeglichen zugehörigen Daches und liefert Leitlinien für die Anforderungen an die Gestaltung des Fundamentes.
Dieses Dokument ist anwendbar, wenn:
a)   der Behälter zylindrisch und auf einer beanspruchungsfähigen Grundplatte befestigt ist, die sich im Wesentlichen auf Bodenebene oder darüber befindet;
b)   der Behälterdurchmesser, in Meter, multipliziert mit der Wandhöhe, in Meter, einen Wert im Bereich von 5 bis 500 ergibt;
c)   der Behälterdurchmesser nicht größer als 100 m und die Gesamthöhe der Wand nicht größer als 50 m ist;
d)   der gespeicherte Stoff die Eigenschaften einer Flüssigkeit hat, die eine vernachlässigbare Reibungskraft auf die Behälterwand ausübt; der gespeicherte Stoff im Rahmen des Aufbereitungsprozesses von kommunalen und industriellen Abwässern einer Behandlung unterzogen werden kann;
e)   der Innendruck im Gasraum oberhalb der Flüssigkeit nicht größer als 50 kPa ist und das innere, partielle Vakuum oberhalb der Flüssigkeit 10 kPa nicht überschreitet;
f)   die Wände des Behälters senkrecht sind;
g)   der Boden des Behälters an der Schnittfläche mit der Wand im Wesentlichen eben ist; der Behälterboden eine Neigung haben kann, damit sein vollständiges Entleeren ermöglicht wird, wobei diese Neigung nicht mehr als 1 : 100 beträgt;
h)   die durch die Behälterfüllung erzeugte Trägheitskraft und Stoßbeanspruchung vernachlässigbar sind;
i)   die Mindestdicke des Behältermantels 1,5 mm beträgt;
j)   der Werkstoff, der für die Herstellung der Stahlbleche verwendet wird, Kohlenstoffstahl ist (Behälter aus Blechen aus Aluminium oder nichtrostendem Stahl fallen nicht in den Anwendungsbereich dieses Dokuments);
k)   die Temperatur der Behälterwand im Einsatz bei allen Betriebsbedingungen innerhalb des Bereiches von −50 °C bis +100 °C liegt.
Dieses Dokument enthält darüber hinaus Einzelheiten zu Verfahren, die während der Montage auf der Baustelle sowie bei Inspektion und Instandhaltung des eingebauten Behälters zu befolgen sind.
Dieses Dokument ist nicht anwendbar für chemische Reaktionsbehälter.
Dieses Dokument umfasst nicht die Feuerbeständigkeit.

Émaux vitrifiés - Conception de réservoirs en acier boulonnés pour le stockage ou le traitement des eaux ou des effluents d'eaux usées urbains ou industriels (ISO 28765:2022)

Le présent document établit les exigences relatives à la conception et à l’utilisation de réservoirs cylindriques en acier boulonnés revêtus d’émail vitrifié pour le stockage ou le traitement des eaux ou des effluents d’eaux usées urbains ou industriels.
Il s’applique à la conception de réservoirs ainsi que de tout toit les couvrant et fournit des recommandations relatives aux exigences concernant la conception de l’assise.
Il s’applique lorsque:
a) le réservoir est cylindrique et qu’il est monté sur une surface portante située en grande partie au niveau du sol ou au-dessus du niveau du sol;
b) le produit du diamètre du réservoir, en mètres, et de la hauteur de paroi, en mètres, est compris entre 5 et 500;
c) le diamètre du réservoir ne dépasse pas 100 m, et la hauteur totale de paroi ne dépasse pas 50 m;
d) le matériau stocké a les caractéristiques d’un liquide, exerçant une force de frottement négligeable sur la paroi du réservoir; il peut être soumis à un traitement faisant partie d’un processus de traitement des effluents d’eaux usées urbains ou industriels;
e) la pression interne de l’espace libre au-dessus du liquide ne dépasse pas 50 kPa et la pression du vide partiel interne au-dessus du liquide ne dépasse pas 10 kPa;
f) les parois du réservoir sont verticales;
g) le fond du réservoir est essentiellement plat à l’intersection avec la paroi; il peut être incliné afin de permettre une vidange complète du réservoir, sa pente ne devant pas dépasser 1 %;
h) la charge d’impact et d’inertie liée au remplissage du réservoir est négligeable;
i) l’épaisseur minimale de l’enveloppe du réservoir est de 1,5 mm;
j) le matériau utilisé pour la fabrication des tôles est un acier au carbone (les réservoirs construits à partir de tôles d’aluminium ou d’acier inoxydable ne relèvent pas du domaine d’application du présent document);
k) la température de la paroi du réservoir en cours de fonctionnement se situe entre −50 °C et +100 °C dans toutes les conditions de fonctionnement.
Le présent document fournit également des informations détaillées concernant les modes opératoires à suivre durant l’installation sur site ainsi que pour l’inspection et l’entretien du réservoir installé.
Il ne s’applique pas aux réservoirs pour réaction chimique.
Il ne couvre pas la résistance au feu.

Steklasti in porcelanski emajli - Projektiranje s steklastim emajlom zaščitenih jeklenih rezervoarjev za skladiščenje ali pripravo vode ali komunalnih ali industrijskih odplak (ISO 28765:2022)

Ta dokument vzpostavlja zahteve za projektiranje in uporabo s steklastim emajlom zaščitenih valjastih jeklenih rezervoarjev za skladiščenje ali pripravo vode ali komunalnih ali industrijskih odplak.
Uporablja se za projektiranje rezervoarjev in povezanih pokrovov ter vključuje navodila glede zahtev za projektiranje temeljev.
Uporablja se v naslednjih primerih:
a) rezervoar je valjaste oblike in nameščen na nosilnem podstavku pretežno na nivoju tal ali nad njim;
b) izdelek s premerom rezervoarja v metrih in višino stene v metrih je znotraj obsega od 5 do 500;
c) premer rezervoarja ne presega 100 m in skupna višina stene ne presega 50 m;
d) skladiščeni material ima lastnosti tekočine z zanemarljivo silo trenja na stene rezervoarja; skladiščeni material je mogoče obdelati v okviru postopka obdelave komunalnih ali industrijskih odplak;
e) notranji pritisk v plinski fazi nad tekočino ne sme presegati 50 kPa, notranji delni vakuum nad tekočino pa ne sme presegati 10 kPa;
f) stene rezervoarja so navpične;
g) dno rezervoarja je ob stiku s steno pretežno ravno; dno rezervoarja ima lahko vgrajen padec, ki omogoča popolno izpraznitev vsebine iz rezervoarja, z naklonom največ 1 : 100;
h) obstaja zanemarljiva vztrajnostna in naletna obremenitev zaradi polnjenja rezervoarja;
i) najmanjša debelina posode rezervoarja je 1,5 mm;
j) material, uporabljen za izdelavo jeklenih plošč, je ogljikovo jeklo (rezervoarji, izdelani iz plošč iz aluminija ali nerjavnega jekla ne spadajo na področje uporabe tega dokumenta);
k) temperatura stene rezervoarja med obratovanjem je v razponu od –50 do 100 °C pri vseh pogojih obratovanja.
Ta dokument navaja tudi podrobnosti o postopkih, ki jih je treba upoštevati pri namestitvi na mestu uporabe ter pri pregledu in vzdrževanju nameščenega rezervoarja.
Ne uporablja se za posode za kemijske reakcije.
Ne zajema odpornosti proti ognju.

General Information

• Status: Published
• Public Enquiry End Date: 12-Apr-2022
• Publication Date: 27-Nov-2022
• ICS: 23.020.10 - Stationary containers and tanks
• ICS: 25.220.50 - Enamels
• Technical Committee: IPKZ - Protection of metals against corrosion
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 23-Nov-2022
• Due Date: 28-Jan-2023
• Completion Date: 28-Nov-2022
• Ref Project: EN ISO 28765:2022 - Vitreous and porcelain enamels - Design of bolted steel tanks for the storage or treatment of water or municipal or industrial effluents and sludges (ISO 28765:2022)

Relations

• Replaces: SIST EN ISO 28765:2016 - Vitreous and porcelain enamels - Design of bolted steel tanks for the storage or treatment of water or municipal or industrial effluents and sludges (ISO 28765:2016)
• Effective Date: 23-Nov-2022

Overview

EN ISO 28765:2022 (CEN) - Vitreous and porcelain enamels - provides requirements and guidance for the design, manufacture, installation, inspection and maintenance of bolted cylindrical steel tanks coated with vitreous (porcelain) enamel for the storage or treatment of water, municipal or industrial effluents and sludges. The standard applies to tanks mounted on a load-bearing base at or above ground level and gives guidance on associated roofs and foundations. It also covers coating quality, protection during shipping and on-site rectification.

Key scope limits include:

• Tanks are cylindrical with vertical walls and a substantially flat floor (slope ≤ 1:100 allowed).
• Product of diameter (m) × wall height (m) between 5 and 500; diameter ≤ 100 m; total wall height ≤ 50 m.
• Minimum shell thickness 1.5 mm; material: carbon steel only (aluminium/stainless steel excluded).
• Internal headspace pressure ≤ 50 kPa and partial vacuum ≤ 10 kPa.
• Stored material behaves as a liquid (negligible wall friction); excludes chemical-reaction vessels and does not cover fire resistance.

Key Topics and Requirements

• Structural design: Loads accounted include hydrostatic pressure, freeboard, axial forces, filling/discharging effects, equipment and access loads, and ancillary items.
• Environmental actions: Guidance for wind, snow, ice and seismic effects where applicable.
• Materials and enamelling: Requirements for carbon-steel sheets, effects of enamelling on steel, enamel coating specification, quality control, inspection frequencies and on-site rectification procedures.
• Fabrication and assembly: Design of bolted shell panels, roof attachments, floor-wall connections, reinforcement of openings (manways, pipe connections, overflows).
• Operational limits: Temperature range of tank walls between −50 °C and +100 °C.
• Installation & maintenance: Procedures for site installation, protection during shipping, inspection regimes and maintenance to preserve enamel integrity.
• Safety considerations: Risk assessment for accidental scenarios (e.g., explosions, uncontrolled input fluctuations) and requirements for cathodic protection considerations.

Applications and Users

This standard is intended for practical use in:

• Design and specification of water storage tanks, wastewater treatment tanks, and sludge/effluent storage for municipal and industrial plants.
• Tank manufacturers, structural and coatings engineers, consultants, utility asset owners, procurement officers, site installers, and inspection/maintenance teams.
• Preparing contract specifications, quality assurance plans, and acceptance tests for enamel-coated bolted steel tanks.

Keywords: EN ISO 28765:2022, vitreous enamel tank design, porcelain enamel, bolted steel tanks, water storage, effluent tanks, tank inspection, enamel coating quality.

Related Standards

Consult complementary standards and national regulations on:

• Metallic and inorganic coatings (coating test methods and corrosion protection)
• Structural steel design and load codes (wind, snow, seismic)
• Foundation and geotechnical design These help ensure full compliance when designing and installing enamel-coated bolted tanks.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2023
Nadomešča:
SIST EN ISO 28765:2016
Steklasti in porcelanski emajli - Projektiranje s steklastim emajlom zaščitenih
jeklenih rezervoarjev za skladiščenje ali pripravo vode ali komunalnih ali
industrijskih odplak (ISO 28765:2022)
Vitreous and porcelain enamels - Design of bolted steel tanks for the storage or
treatment of water or municipal or industrial effluents and sludges (ISO 28765:2022)
Emails und Emaillierungen - Gestaltung von verschraubten Stahlbehältern für die
Speicherung oder Behandlung von Wasser oder kommunalen und industriellen
Abwässern und Abwasserschlamm (ISO 28765:2022)
Émaux vitrifiés - Conception de réservoirs en acier boulonnés pour le stockage ou le
traitement des eaux ou des effluents d'eaux usées urbains ou industriels (ISO
28765:2022)
Ta slovenski standard je istoveten z: EN ISO 28765:2022
ICS:
23.020.10 Nepremične posode in Stationary containers and
rezervoarji tanks
25.220.50 Emajlne prevleke Enamels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 28765
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2022
EUROPÄISCHE NORM
ICS 25.220.50 Supersedes EN ISO 28765:2016
English Version
Vitreous and porcelain enamels - Design of bolted steel
tanks for the storage or treatment of water or municipal or
industrial effluents and sludges (ISO 28765:2022)
Émaux vitrifiés - Conception de réservoirs en acier Emails und Emaillierungen - Gestaltung von
boulonnés pour le stockage ou le traitement des eaux verschraubten Stahlbehältern für die Speicherung oder
ou des effluents d'eaux usées urbains ou industriels Behandlung von Wasser oder kommunalen und
(ISO 28765:2022) industriellen Abwässern und Abwasserschlamm (ISO
28765:2022)
This European Standard was approved by CEN on 23 October 2022.

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, Türkiye 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
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 28765:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 28765:2022) 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 May 2023, and conflicting national standards shall be
withdrawn at the latest by May 2023.
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 28765:2016.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 28765:2022 has been approved by CEN as EN ISO 28765:2022 without any modification.

INTERNATIONAL ISO
STANDARD 28765
Third edition
2022-10
Vitreous and porcelain enamels —
Design of bolted steel tanks for the
storage or treatment of water or
municipal or industrial effluents and
sludges
Émaux vitrifiés — Conception de réservoirs en acier boulonnés pour
le stockage ou le traitement des eaux ou des effluents d'eaux usées
urbains ou industriels
Reference number
ISO 28765:2022(E)
ISO 28765:2022(E)
© ISO 2022
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 28765:2022(E)
Contents Page
Foreword .v
1 S c op e . 1
2 Nor m at i ve r ef er enc e s . 2
3 T erms and definitions . 2
4 S y mb ol s . 4
5 Un it s. 5
6 I nformation and requirements to be agreed and documented . 6
6.1 General . 6
6.2 I nformation to be provided by the purchaser . 6
6.3 I nformation to be provided by the designer . 7
7 A ppl ic able s t a nd a r d s .7
8 L o ad s . 8
8.1 General . 8
8 . 2 C ont ent s . 8
8.2.1 General . 8
8.2.2 F reeboard . 8
8.2.3 Hydrostatic pressure . 8
8.2.4 A xial wall forces. 8
8.2.5 F illing and discharging . 8
8.3 T ank structure . 9
8.4 Roof . 9
8.5 E quipment loads . 9
8.5.1 General . 9
8.5.2 S tatic load . 9
8.5.3 Dynamic load . 9
8 . 6 Ac c e s s. 9
8.7 Environmental . 10
8.7.1 G eneral . 10
8.7.2 S eismic action. 10
8 .7. 3 W i nd . 10
8.7.4 Snow . 10
8 .7. 5 Ic e . 10
8.8 A ncillary items . 10
9 D e sig n .11
9.1 G eneral . 11
9.2 Steel . 11
9.2.1 Sp ecification . 11
9.2.2 E ffects of the enamelling process . 11
9.3 T ank . 11
9.3.1 Load factors . 11
9.3.2 T ank walls . 12
9.3.3 Tank roof . . 15
9.3.4 Attachment of walls to floor . 15
9.3.5 Tank floor .15
9.3.6 Ancillary items . 16
9.3.7 Cathodic protection . 16
9.4 Openings . 16
9.4.1 Access manway . 16
9.4.2 Pipe connections . 16
9.4.3 O verflows . 17
9.4.4 Reinforcement of manways and pipe connections in the tank shell . 17
iii
ISO 28765:2022(E)
9.4.5 Connections in the roof . 17
9.5 E ffects of accidents . 17
9.5.1 R isk assessment . 17
9.5.2 E xplosions . 18
9.5.3 Uncontrolled fluctuation in input stream characteristics . 18
10 Vitreous enamel coating .18
10.1 V itreous enamel . . 18
10.2 C oating . 18
10.3 V itreous enamel quality . 18
10.3.1 Preparation and test frequency . 18
10 . 3 . 2 I n s p e c t ion . 18
10.3.3 On-site rectification . . 19
10.4 P rotection during shipping . 25
10.5 Maintenance . 25
11 I n s t a l l at ion .25
11.1 General information.25
11.2 Foundations . 25
11.3 I nspection of the vitreous enamel coating at the construction site . 25
12 D i s i n f e c t ion .25
Bibliography .27
iv
ISO 28765:2022(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,
in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/
TC 262, Metallic and other inorganic coatings, including for corrosion protection and corrosion testing of
metals and alloys, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 28765:2016), which has been technically
revised.
The main changes are as follows:
— the normative references have been updated;
— the terms and definitions have been updated;
— additional information relating to tank installation requirements, foundation requirements, tank
roof openings and tank disinfection requirements have been added;
— additional tank applications have been added to the application guide along with their associated
quality requirements.
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.
v
INTERNATIONAL STANDARD ISO 28765:2022(E)
Vitreous and porcelain enamels — Design of bolted steel
tanks for the storage or treatment of water or municipal or
industrial effluents and sludges
1 S cope
This document specifies the requirements for the design and use of vitreous enamel coated bolted
cylindrical steel tanks for the storage or treatment of water or municipal or industrial effluents and
sludges.
It is applicable to the design of the tank and any associated roof and gives guidance on the requirements
for the design of the foundation.
It is applicable where:
a) the tank is cylindrical and is mounted on a load-bearing base substantially at or above ground level;
b) the product of the tank diameter in metres and the wall height in metres lies within the range
5 to 500;
c) the tank diameter does not exceed 100 m and the total wall height does not exceed 50 m;
d) the stored material has the characteristics of a liquid, exerting a negligible frictional force on the
tank wall; the stored material can be undergoing treatment as part of a municipal or industrial
effluent treatment process;
e) the internal pressure in the headspace above the liquid does not exceed 50 kPa and the internal
partial vacuum above the liquid does not exceed 10 kPa;
f) the walls of the tank are vertical;
g) the floor of the tank is substantially flat at its intersection with the wall; the floor of the tank can
have a rise or fall built in to allow complete emptying of the tank contents, the slope of which does
not exceed 1:100;
h) there is negligible inertial and impact load due to tank filling;
i) the minimum thickness of the tank shell is 1,5 mm;
j) the material used for the manufacture of the steel sheets is carbon steel (tanks constructed of
sheets made from aluminium or stainless steel are outside the scope of this document);
k) the temperature of the tank wall during operation is within the range −50 °C to +100 °C under all
operating conditions.
This document also gives details of procedures to be followed during installation on site and for
inspection and maintenance of the installed tank.
It does not apply to chemical-reaction vessels.
It does not cover resistance to fire.
ISO 28765:2022(E)
2 Normat ive 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 2178, Non-magnetic coatings on magnetic substrates — Measurement of coating thickness — Magnetic
method
ISO 2746:2015, Vitreous and porcelain enamels — High voltage test
ISO 2859-1, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by
acceptance quality limit (AQL) for lot-by-lot inspection
ISO 4532, Vitreous and porcelain enamels — Determination of the resistance of enamelled articles to
impact — Pistol test
ISO 6370-2, Vitreous and porcelain enamels — Determination of the resistance to abrasion — Part 2: Loss
in mass after sub-surface abrasion
ISO 6769, Vitreous and porcelain enamels — Determination of surface scratch hardness according to the
Mohs scale
ISO 8289-1:2020, Vitreous and porcelain enamels — Low-voltage test for detecting and locating defects —
Part 1: Swab test for non-profiled surfaces
ISO 15686-1, Buildings and constructed assets — Service life planning — Part 1: General principles and
framework
ISO 19496-1, Vitreous and porcelain enamels — Terminology — Part 1: Terms and definitions
ISO 28706-1:2008, Vitreous and porcelain enamels — Determination of resistance to chemical corrosion
— Part 1: Determination of resistance to chemical corrosion by acids at room temperature
ISO 28706-2:2017, Vitreous and porcelain enamels — Determination of resistance to chemical corrosion —
Part 2: Determination of resistance to chemical corrosion by boiling acids, boiling neutral liquids, alkaline
liquids and/or their vapours
ISO 28706-3:2017, Vitreous and porcelain enamels — Determination of resistance to chemical corrosion —
Part 3: Determination of resistance to chemical corrosion by alkaline liquids using a hexagonal vessel or a
tetragonal glass bottle
ISO 28706-4:2016, Vitreous and porcelain enamels — Determination of resistance to chemical corrosion
— Part 4: Determination of resistance to chemical corrosion by alkaline liquids using a cylindrical vessel
ISO 28763:2019, Vitreous and porcelain enamels — Regenerative, enamelled and packed panels for air-gas
and gas-gas heat exchangers — Specifications
EN 1998-4, Eurocode 8 — Design of structures for earthquake resistance — Part 4: Silos, tanks and
pipelines
EN 10209:2013, Cold rolled low carbon steel flat products for vitreous enamelling — Technical delivery
conditions
ANSI/AWWA D 103, Factory-Coated Bolted Steel Tanks for Water Storage
3 T erms and definitions
For the purposes of this document, the terms and definitions given in ISO 19496-1 and the following
apply.
ISO 28765:2022(E)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
brief
working document which specifies at any point in time the relevant needs and aims of the project,
the resources to be provided by the client (3.2), the details of the project and any applicable design
requirements within which all subsequent briefing (when needed) and designing can take place
3.2
client
person or organization that requires a tank (3.18) to be provided, altered or extended and is responsible
for initiating and approving the brief (3.1)
3.3
defect
void, break, crack, discontinuity, blister, foreign inclusion or contamination of the vitreous enamel
coating
3.4
designer
person or organization responsible for stating the shape and specification of the component to be
designed
3.5
design life
service life (3.17) intended by the designer (3.4)
3.6
discontinuity free
vitreous enamel coating which does not allow an electric current to pass through to the steel substrate
3.7
enamel supplier
person or organization supplying materials for use by the vitreous enameller (3.19) in the enamelling
process
3.8
freeboard
distance between the top of the cylindrical-tank vertical shell wall and the surface of the contained
liquid (3.11) at the specified operating level
3.9
headspace pressure
pressure within a roofed tank (3.18) above the stored liquid (3.11)
3.10
inspection area
area inside a boundary 25 mm from any panel edge or hole and outside a boundary 25 mm from any
opening or hole within the body of a panel
3.11
liquid
bulk substance that exerts substantially the same vertical and horizontal pressures and has no fixed
shape
ISO 28765:2022(E)
3.12
maintenance
combination of all technical and associated administrative actions during the service life (3.17) to retain
a tank (3.18) or its parts in a state in which it can perform its required function
3.13
manufacturer
person or organization that manufactures the tank (3.18) or parts of the tank
3.14
purchaser
person or organization purchasing the tank (3.18) from the supplier (3.16)
Note 1 to entry: The purchaser can also be the client (3.2).
3.15
rectification
return of a tank (3.18) or its parts to an acceptable condition by the renewal, replacement or repair of
worn, damaged or degraded parts
3.16
supplier
person or organization that supplies the tank (3.18) or parts of the tank
3.17
service life
period of time after installation during which the tank (3.18) or its parts meets or exceeds the
performance requirements
3.18
tank
cylindrical, vertical shell for containing liquid (3.11), with or without a roof, which is constructed from
curved vitreous enamelled single or laminated steel panels bolted together on the construction site and
mounted on a base which can also form the floor of the container
3.19
vitreous enameller
person undertaking and controlling the process of preparing the steel sheets and applying the vitreous
enamel coating to the surfaces of the steel sheets
Note 1 to entry: The vitreous enameller will normally be the manufacturer (3.13).
4 Symbols
For the purposes of this document, the following symbols apply.
D tank diameter
E Young's modulus of elasticity
F static hoop force
H
g acceleration due to gravity
H depth of liquid at point under consideration, measured from the liquid surface at the maximum
possible filling level
H total vertical wall height
l length of shell between intermediate stiffeners
ISO 28765:2022(E)
I second moment of area of a stiffener
z
p headspace pressure
h
p hydrostatic pressure
n
r tank radius
q critical external buckling pressure
r,cr
q maximum stagnation pressure due to wind
wmax
t shell plate thickness
ν Poisson's ratio
w proportion of dissolved solids in sludge
γ maximum partial load factor
ρ relative density of a liquid
ρ relative density of sludge
s
ρ relative density of municipal sewage sludge
ds
σ stress
σ critical axial buckling resistance
z,cr
cr (subscript) critical
ds (subscript) dissolved solids
h (subscript) headspace
max (subscript) maximum value
n (subscript) normal to the tank wall
s (subscript) sludge
w (subscript) wind
z (subscript) coincident with the central axis of a shell of revolution
5 Units
The use of one of the following sets of consistent units is recommended.
dimensions: m, mm
3 3
unit weight: kN/m , N/mm
forces and loads: kN, N
line forces and line loads: kN/m, N/mm
pressures and area-distributed actions: kPa, MPa (1 MPa = 1 N/mm )
ISO 28765:2022(E)
3 3
unit mass: kg/m , kg/mm
2 2
acceleration: km/s , m/s
membrane-stress resultants: kN/m, N/mm
bending-stress resultants: kNm/m, Nmm/mm
stresses and elastic moduli: kPa, MPa
6 In formation and requirements to be agreed and documented
6.1 General
For the safe design and manufacture of the tank and associated parts, the brief and specification shall
be agreed between the contracting parties.
6.2 Information t o be provided by the purchaser
The purchaser shall provide the supplier with a specification that shall include, but not be limited to,
the following:
a) The specification of the stored liquid that shall include, but not be limited to, the following:
1) the name and/or a description of the liquid;
2) the relative density;
3) any relevant properties or characteristics particular to the liquid to be stored;
4) the operating-temperature range.
b) The environmental conditions that shall include, but not be limited to, the following:
1) wind;
2) seismic action;
3) snow;
4) ice;
5) temperature ranges.
c) The use and planned dimensions of the tank that shall include, but not be limited to, the following:
1) the rates of fill and discharge;
2) a summary describing the purpose of the tank and its method of operation;
3) the net effects of the process on the tank or any of its components;
4) the tank dimensions.
d) The planned location of all openings in the tank shell and roof.
e) Attached equipment:
1) method of attachment;
2) dead and live loads;
ISO 28765:2022(E)
3) connections.
f) The proximity of other tanks and buildings.
6.3 Information t o be provided by the designer
The designer shall provide essential data concerning the design limitations of the tank that shall
include, but not be limited to, the following:
a) the name and a description of the stored liquid or liquids;
b) the range of the relative densities of the stored liquid or liquids;
c) the limits of the environmental criteria used in the design, including, where relevant, the design
wind speed, the design operating-temperature range, the design snow load and the seismic zone
and seismic coefficients;
d) the maximum access and superimposed loads used in the design;
e) a maintenance plan conforming to the requirements of ISO 15686-1;
f) guidance concerning change of use;
g) all relevant data assumed by the designer in the design process.
7 Applica ble standards
All activities specified in this document shall be carried out under an appropriate quality management
[1]
system (e.g. ISO 9001 ).
The designer and client shall agree, through consultation, upon the applicable standards to be used for
design purposes. Where provision is not made within this document, other international or national
standards may be specified.
The applicable standards agreed upon shall include, but not be limited to, standards providing details
of parameters for the following design procedures:
a) hydrostatic loads;
b) wind loads;
c) seismic loads;
d) access loads;
e) snow loads;
f) rain loads;
g) load factors;
h) sheet strength calculations;
i) bolt strength calculations;
j) stability calculations;
k) foundation design.
ISO 28765:2022(E)
8 Loads
8.1 General
All tanks and supporting structures shall be designed on a “limit state design” basis.
8.2 Contents
8.2.1 General
Loads due to the liquid shall be calculated considering:
a) the relative density of the specified range of liquids to be stored in the tank;
b) the geometry of the tank;
c) the maximum possible depth of the liquid in the tank.
If the liquid to be stored is sludge, and unless reliable or measured data are provided, the value of the
relative density of the sludge, ρ , may be estimated by simple proportion using Formula (1):
s
ρρ=+11w()− (1)
sds
where ρ is taken as 1,9 in the case of municipal sewage sludge.
ds
8.2.2 Freeboard
The freeboard used for design purposes shall be as agreed between the client and the designer.
Where the tank is designed for seismic conditions, sufficient freeboard shall be provided to contain
the sloshing wave shall be determined from the applicable standard. This shall take account of any
equipment and structural members in the top of the tank.
8.2.3 Hydrostatic pressure
Determine the hydrostatic pressure, p , in kPa, acting on the tank shell at depth H using Formula (2):
n
pH=×ρ×+gp (2)
nh
8.2.4 Axial wall forces
The axial wall forces per unit shell width shall be determined taking account of the following:
a) the tank dead weight;
b) the imposed load;
c) the axial tension and compression due to the wind overturning moment;
d) the axial tension and compression due to seismic actions.
8.2.5 Filling and discharging
The method of filling and discharging the liquid can affect the load and shall be considered by the
designer. These influences include, but are not limited to, the following:
a) the filling position: the inlet stream impinging on the tank wall;
ISO 28765:2022(E)
b) completion of discharge: the risk of a hydrodynamic “water hammer” effect if the outlet is closed
rapidly;
c) fatigue: the effect of the frequency of the filling and discharge cycles;
d) pressure and/or partial vacuum;
e) venting;
f) rapid changes in temperature.
8.3 Tank structure
The dead load shall be determined as the total weight of all structural components and permanent
fittings.
8.4 Roof
The tank designer shall take account of all forces on the tank shell from the roof. These forces may
include, but are not necessarily limited to, the following:
a) distributed in-plane and radial forces transmitted by structural roof members;
b) concentrated in-plane and radial forces resulting from structural features of the roof;
c) asymmetrical forces due to uneven distribution of imposed roof loads;
d) forces induced in the roof by differential settlement of the foundation.
8.5 Equipment loads
8.5.1 General
In the calculation of the total load on the tank, the designer shall take into account the effect of the
attached equipment for both static and dynamic loads.
8.5.2 Static load
The static load of any equipment attached to the tank shall be determined as the weight of the
equipment, including associated mounting fixtures and any liquid within the equipment, as advised by
the purchaser.
8.5.3 Dynamic load
The dynamic forces caused by any equipment shall be determined, where applicable. They may include,
but are not necessarily limited to, the following:
a) starting and operating forces from any rotating or moving piece of equipment mounted on or in the
tank;
b) forces imposed on the tank or its attachments from installed process equipment (e.g. forces from
restraining cables of floating aerators);
c) forces imposed on the tank or its attachments due to the operation of installed process equipment
(e.g. forces on attached baffle plates due to forced movement of the tank contents).
8.6 Access
Where a roof is not designed to be accessible other than for normal cleaning and repair, the roof shall be
designed using a uniform load of 0,6 kN/m .
ISO 28765:2022(E)
Where the roof is designed to be accessible, it shall be designed using an imposed load appropriate for
the intended usage taken from the applicable code but not less than1,5 kN/m .
Unless otherwise specified, loads transferred to the roof from walkways and platforms shall be
assessed based on a uniform load appropriate for the intended usage taken from the applicable code,
but not less than 3,0 kN/m applied to the walkway or platform.
8.7 Environmental
8.7.1 General
Environmental loads shall be determined taking into account the design life of the tank.
8.7.2 S eismic action
Where relevant, seismic action shall be determined from the applicable standard.
The designer shall consider the following as a minimum requirement:
a) horizontal acceleration;
b) vertical acceleration;
c) sloshing of the contents;
d) the anchorage method;
e) dynamic ground response.
[11]
Guidance on the determination of seismic action can be found in the International Building Code, in
[5]
ANSI/AWWA D 103 and in EN 1998-1 and EN 1998-4. When applying ANSI/AWWA D103, the latest
version from which seismic data for the site location is available shall be used. When applying ANSI/
AWWA D 103 in locations outside North America, zones determined from the 1997 Uniform Building
[10]
Code may be taken as equivalent.
8.7.3 Wind
The wind speed and pressure to be used for design purposes shall be determined from the applicable
standard for the site location.
8.7.4 Snow
Where applicable, the load induced by snow shall be determined from the applicable standard for the
site location.
8.7.5 Ice
Where applicable, the load induced by ice on the roof shall be determined from the applicable standard
for the site location.
8.8 Ancillary items
The designer shall take account of the forces from ancillary items such as ladders, platforms, valves and
machinery.
ISO 28765:2022(E)
9 Design
9.1 General
The design of the tank shall be carried out using a “limit state design” approach. Design life assessment
shall be based on ISO 15686-1.
9.2 Steel
9.2.1 Specification
The steel used shall have a specification, as agreed between the manufacturer, the designer and the
steel supplier, having due regard to the requirements of the enamelling process.
[7] [6] [8]
NOTE Steels conforming to the requirements of EN 10111, EN 10025-1 and EN 10149-1 (including
[9]
grades DD 11, S235, S420, S460
...