EN ISO 28765:2016

SLOVENSKI STANDARD
01-april-2016
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SIST EN ISO 28765:2012
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MHNOHQLKUH]HUYRDUMHY]DVNODGLãþHQMHDOLSULSUDYRYRGHDOLNRPXQDOQLKDOL
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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)
Emails und Emaillierungen - Gestaltung von verschraubten Stahlbehältern für die
Speicherung oder Behandlung von Wasser oder kommunalen und industriellen
Abwässern und Abwasserschlamm (ISO 28765:2016)
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
28765:2016)
Ta slovenski standard je istoveten z: EN ISO 28765:2016
ICS:
23.020.10 1HSUHPLþQHSRVRGHLQ Stationary containers and
UH]HUYRDUML 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
February 2016
EUROPÄISCHE NORM
ICS 25.220.50 Supersedes EN ISO 28765:2011
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 28765:2016)
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 28765:2016) industriellen Abwässern und Abwasserschlamm (ISO
28765:2016)
This European Standard was approved by CEN on 19 December 2015.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 28765:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 28765:2016) 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” 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 August 2016, and conflicting national standards shall
be withdrawn at the latest by August 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 28765:2011.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 28765:2016 has been approved by CEN as EN ISO 28765:2016 without any modification.
INTERNATIONAL ISO
STANDARD 28765
Second edition
2016-01-15
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 28765:2016(E)
©
ISO 2016
ISO 28765:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

ISO 28765:2016(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 4
5 Units . 5
6 Information and requirements to be agreed and documented . 6
6.1 General . 6
6.2 Information to be provided by the purchaser . 6
6.3 Information to be provided by the designer . 7
7 Applicable standards . 7
8 Loads . 7
8.1 General . 7
8.2 Contents . 8
8.2.1 General. 8
8.2.2 Freeboard . 8
8.2.3 Hydrostatic pressure . 8
8.2.4 Axial wall forces . 8
8.2.5 Filling and discharging . 8
8.3 Tank structure . 9
8.4 Roof . 9
8.5 Equipment loads . 9
8.5.1 General. 9
8.5.2 Static load . 9
8.5.3 Dynamic load . 9
8.6 Access . 9
8.7 Environmental .10
8.7.1 General.10
8.7.2 Seismic action .10
8.7.3 Wind .10
8.7.4 Snow .10
8.7.5 Ice .10
8.8 Ancillary items .10
9 Design .10
9.1 General .10
9.2 Steel .11
9.2.1 Specification . .11
9.2.2 Effects of the enamelling process .11
9.3 Tank .11
9.3.1 Load factors .11
9.3.2 Tank 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 Overflows .16
9.4.4 Reinforcement of manways and pipe connections in the tank shell .17
ISO 28765:2016(E)
9.4.5 Connections in the roof .17
9.5 Effects of accidents .17
9.5.1 Risk assessment . .17
9.5.2 Explosions.17
9.5.3 Uncontrolled fluctuation in input stream characteristics .18
10 Vitreous-enamel coating .18
10.1 Vitreous enamel .18
10.2 Coating .18
10.3 Vitreous-enamel quality .18
10.3.1 Preparation and test frequency .18
10.3.2 Inspection .18
10.3.3 On-site rectification .19
10.4 Protection during shipping .23
10.5 Maintenance .23
11 Installation .23
11.1 General guidance .23
11.2 Foundations .23
11.3 Inspection of the vitreous-enamel coating at the construction site .23
12 Disinfection .23
Bibliography .24
iv © ISO 2016 – All rights reserved

ISO 28765:2016(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 107, Metallic and other inorganic coatings.
This second edition cancels and replaces the first edition (ISO 28765:2008), which has been
technically revised.
INTERNATIONAL STANDARD ISO 28765:2016(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 Scope
This International Standard establishes 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 applies to the design of the tank and any associated roof and gives guidance on the requirements for
the design of the foundation.
It applies 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 may 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 may
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 International Standard);
k) the temperature of the tank wall during operation is within the range −50 °C to +100 °C under all
operating conditions.
This International Standard 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.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 28765:2016(E)
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 8289:2000, Vitreous and porcelain enamels — Low voltage test for detecting and locating defects
ISO 15686-1, Buildings and constructed assets — Service life planning — Part 1: General principles
and framework
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 28706-2:2008, Vitreous and porcelain enamels — Determination of resistance to chemical corrosion —
Part 2: Determination of resistance to chemical corrosion by boiling acids, boiling neutral liquids and/or
their vapours
ISO 28706-3:2008, 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
ISO 28706-4:2008, 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 28763:2008, Vitreous and porcelain enamels — Regenerative, enamelled and packed panels for air-gas
and gas-gas heat exchangers — Specifications
EN 15771, Vitreous and porcelain enamels — Determination of surface scratch hardness according to
the Mohs scale
EN 1993-1-6, Eurocode 3 — Design of steel structures — Part 1-6: Strength and Stability of Shell Structures
EN 1993-4-1, Eurocode 3 — Design of steel structures — Part 4-1: Silos
EN 1993-4-2, Eurocode 3 — Design of steel structures — Part 4-2: Tanks
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 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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, the details of the project and any applicable design requirements
within which all subsequent briefing (when needed) and designing can take place
2 © ISO 2016 – All rights reserved

ISO 28765:2016(E)
3.2
client
person or organization that requires a tank to be provided, altered or extended and is responsible for
initiating and approving the brief
3.3
defect
break in the surface of the vitreous enamel
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 intended by the designer
3.6
discontinuity
weakness within the vitreous enamel coating that is detected by spark testing
3.7
enamel supplier
person or organization supplying materials for use by the vitreous enameller 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 at the specified operating level
3.9
headspace pressure
pressure within a roofed tank above the stored liquid
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
3.12
maintenance
combination of all technical and associated administrative actions during the service life to retain a
tank or its parts in a state in which it can perform its required function
3.13
manufacturer
person or organization that manufactures the tank or parts of the tank
3.14
purchaser
person or organization purchasing the tank from the supplier
Note 1 to entry: The purchaser can also be the client.
ISO 28765:2016(E)
3.15
rectification
return of a tank 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 or parts of the tank
3.17
service life
period of time after installation during which the tank or its parts meets or exceeds the performance
requirements
3.18
tank
cylindrical, vertical shell for containing liquid, with or without a roof, which is constructed from
vitreous-enamelled curved steel panels bolted together on the construction site and mounted on a base
which may 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.
3.20
vitreous enamel
substantially vitreous, or glassy inorganic silica coating bonded to metallic substrate by fusion at a
temperature above 480 °C
Note 1 to entry: This coating is applied for protective functional and/or aesthetic purposes.
Note 2 to entry: This coating is produced by the proprietary formulation of silica glass, minerals and clays to
produce a sprayable medium, dry or suspended in water on to the surface of the metallic substrate, and its
subsequent fusion bonding.
4 Symbols and abbreviated terms
For the purposes of this document, the following symbols and abbreviated terms 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 maxi-
mum possible filling level
H total vertical wall height
l length of shell between intermediate stiffeners
I second moment of area of a stiffener
z
p static liquid pressure at a specified depth
n
4 © ISO 2016 – All rights reserved

ISO 28765:2016(E)
p headspace pressure
h
r tank radius
q critical external buckling pressure
r,cr
q maximum stagnation pressure due to wind
wmax
w proportion of dissolved solids in sludge
t shell plate thickness
ν Poisson’s ratio
γ partial load factor
ρ relative density of a liquid
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
φ (subscript) coincident with the radial 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 kPa, MPa
actions:
3 3
— unit mass: kg/m , kg/mm
2 2
— acceleration: km/s , m/s
— membrane-stress resultants: kN/m, N/mm
ISO 28765:2016(E)
— bending-stress resultants: kNm/m, Nmm/mm
— stresses and elastic moduli: kPa, MPa (1 MPa = 1 N/mm )
6 Information and requirements to be agreed and documented
6.1 General
For the safe design and manufacture of the tank and associated parts, the specification shall be agreed
between the contracting parties.
6.2 Information to 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;
3) connections.
f) The proximity of other tanks and buildings.
6 © ISO 2016 – All rights reserved

ISO 28765:2016(E)
6.3 Information to 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 Applicable standards
All activities specified in this International Standard shall be carried out under an appropriate quality
[2]
management system. A quality management system conforming to ISO 9001 will be deemed to satisfy
this requirement.
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 International Standard, 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.
8 Loads
8.1 General
All tanks and supporting structures shall be designed on a “limit state design” basis.
ISO 28765:2016(E)
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 determined in accordance with EN 1998-4. 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;
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;
8 © ISO 2016 – All rights reserved

ISO 28765:2016(E)
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 .
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.
ISO 28765:2016(E)
8.7 Environmental
8.7.1 General
Environmental loads shall be determined taking into account the design life of the tank.
8.7.2 Seismic 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.
Guidance on the determination of seismic action can be found in the International Building Code, in
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
[18]
Building 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.
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.
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ISO 28765:2016(E)
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.
[8] [7] [9]
NOTE Steels conforming to the requirements of EN 10111, EN 10025-1 and EN 10149–1 (including
[17]
grades DD 11, S235, S420 and S460), ASTM A 1011 and other standards can be used successfully for vitreous
enamelling with appropriate pre-treatments.
9.2.2 Effects of the enamelling process
The designer shall take account of the effects of the vitreous-enamelling process on the strength
properties of the steel and shall make details of such effects available to the client on request.
The effect of the enamelling process shall be assessed and monitored over a period of time, using a
regular and documented test regime from which steel strength properties can be predicted with a
95 % confidence level.
Where regular and documented testing is not carried out, the yield and tensile strengths of the
enamelled steel used for design purposes shall be reduced by 30 % from the guaranteed minimum
strengths confirmed by the steel manufacturer.
9.3 Tank
9.3.1 Load factors
The load factors used in the design process shall be taken from Table 1.
Table 1 — Load factors
Maximum load factor
Basic load case
γ
Dead load 1,4
Dead load acting with wind load, seismic 1,2
load or imposed load
Liquid load 1,4
Imposed load 1,6
Imposed load acting with wind load 1,2
Wind load 1,4
Wind load acting with imposed load 1,2
Snow 1,4
Snow load in determining seismic loads 0,2
Snow load acting with seismic load 0,2
a
Seismic load 1,2
An
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