Unfired pressure vessels - Requirements for the design and fabrication of pressure vessels and pressure vessel parts constructed from cast iron with an elongation after fracture equal or less than 15 %

This European Standard specifies requirements for the design, material, manufacturing and testing of pressure vessels and pressure vessel parts made from materials for which details are specified from the following material standards for specific grades which meet the criterion of an elongation after fracture less than or equal to 15 %:
-   EN 1561, Founding - Grey cast irons;
-   EN 1563, Founding - Spheroidal graphite cast irons;
-   EN 13835, Founding - Austenitic cast irons.
The allowed content of the vessel or pressure part is a fluid of group 2 only, according to the Directive 97/23/EC.

Unbefeuerte Druckbehälter - Anforderungen an die Konstruktion und Herstellung von Druckbehältern und Druckbehälterteilen aus Gusseisen mit einer Bruchdehnung von 15 % oder weniger

Dieses Dokument legt die Anforderungen an die Konstruktion, den Werkstoff, die Herstellung sowie die Prüfung von Gusseisen-Druckbehältern und -Druckbehälterteilen aus Werkstoffen fest, für die Einzelheiten in den folgenden Werkstoffnormen für spezifische Werkstoffsorten festgelegt sind, die die Kriterien hinsichtlich einer Bruchdehnung ≤ 15 % erfüllen.
-   EN 1561:2011, Gießereiwesen - Gusseisen mit Lamellengraphit;
-   EN 1563:2018, Gießereiwesen - Gusseisen mit Kugelgraphit;
-   EN 13835:2012, Gießereiwesen - Austenitische Gusseisen.
Die Anwendung dieses Dokuments beschränkt sich auf Druckgeräte und Druckteile, die ein Fluid der Gruppe 2 (nicht gefährliche Flüssigkeit) gemäß der Druckgeräterichtlinie des Europäischen Parlaments enthalten.

Récipients sous pression non soumis à la flamme - Exigences pour la conception et la fabrication des récipients et parties sous pression moulés en fonte à allongement, après rupture, inférieur ou égal à 15 %

Le présent document spécifie les prescriptions relatives à la conception, aux matériaux, à la fabrication et aux essais des récipients sous pression et de leurs parties sous pression fabriqués à l’aide de matériaux pour lesquels les informations fournies sont issues des normes de matériau suivantes pour des nuances spécifiques remplissant le critère d’un allongement après rupture inférieur ou égal à 15 % :
-   EN 1561:2011, Fonderie - Fonte à graphite lamellaire ;
-   EN 1563:2018, Fonderie - Fonte à graphite sphéroïdal ;
-   EN 13835:2012, Fonderie - Fontes austénitiques.
L’application du présent document est limité aux équipements sous presssion et aux parties sous pression contenant un fluide du groupe 2 (fluide non-dangereux) conformément à la législation Européenne des équipements sous presssion.

Nekurjene tlačne posode - Zahteve za konstruiranje in izdelavo tlačnih posod in njihovih delov iz litega železa z raztezkom ob porušitvi, enakim ali manjšim kot 15 %

Ta evropski standard določa zahteve za konstruiranje, materiale, izdelavo in preskušanje tlačnih posod in njihovih delov iz materialov, katerih podrobnosti so opredeljene na podlagi naslednjih standardov za materiale za posebne ocene, ki izpolnjujejo merilo raztezka ob porušitvi, enakega ali manjšega kot 15 %:
–   EN 1561, Livarstvo – Siva litina;
–   EN 1563, Livarstvo – (Siva) litina s kroglastim grafitom;
–   EN 13835, Livarstvo – Avstenitna siva litina.
Dovoljena vsebina posode ali tlačnega dela je le tekočina skupine 2 v skladu z Direktivo 97/23/ES.

General Information

Status
Published
Public Enquiry End Date
03-Feb-2019
Publication Date
18-Aug-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
03-Aug-2022
Due Date
08-Oct-2022
Completion Date
19-Aug-2022

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SLOVENSKI STANDARD
SIST EN 15776:2022
01-september-2022
Nadomešča:
SIST EN 15776:2011+A1:2016
Nekurjene tlačne posode - Zahteve za konstruiranje in izdelavo tlačnih posod in
njihovih delov iz litega železa z raztezkom ob porušitvi, enakim ali manjšim kot 15
%
Unfired pressure vessels - Requirements for the design and fabrication of pressure
vessels and pressure vessel parts constructed from cast iron with an elongation after
fracture equal or less than 15 %
Unbefeuerte Druckbehälter - Anforderungen an die Konstruktion und Herstellung von
Druckbehältern und Druckbehälterteilen aus Gusseisen mit einer Bruchdehnung von 15
% oder weniger
Récipients sous pression non soumis à la flamme - Exigences pour la conception et la
fabrication des récipients et parties sous pression moulés en fonte à allongement, après
rupture, inférieur ou égal à 15 %
Ta slovenski standard je istoveten z: EN 15776:2022
ICS:
23.020.32 Tlačne posode Pressure vessels
77.140.80 Železni in jekleni ulitki Iron and steel castings
SIST EN 15776:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 15776:2022

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SIST EN 15776:2022


EN 15776
EUROPEAN STANDARD

NORME EUROPÉENNE

July 2022
EUROPÄISCHE NORM
ICS 23.020.30 Supersedes EN 15776:2011+A1:2015
English Version

Unfired pressure vessels - Requirements for the design
and fabrication of pressure vessels and pressure vessel
parts constructed from cast iron with an elongation after
fracture equal or less than 15 %
Récipients sous pression non soumis à la flamme - Unbefeuerte Druckbehälter - Anforderungen an die
Exigences pour la conception et la fabrication des Konstruktion und Herstellung von Druckbehältern und
récipients et parties sous pression moulés en fonte à Druckbehälterteilen aus Gusseisen mit einer
allongement, après rupture, inférieur ou égal à 15 % Bruchdehnung von 15 % oder weniger
This European Standard was approved by CEN on 6 May 2020.

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
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 15776:2022 E
worldwide for CEN national Members.

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SIST EN 15776:2022
EN 15776:2022 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, units and symbols . 7
3.1 Terms and definitions . 7
3.2 Symbols . 9
3.3 Inter relation of thicknesses definitions (EN 13445-6:2021) . 11
4 Materials, limitations and service conditions. 11
4.1 Materials and limitations on temperature, maximum allowable pressure and energy
content . 11
4.2 Cyclic loading . 13
5 Design requirements . 14
5.1 Design principle . 14
5.2 Conceptual design and construction drawings . 15
5.3 Static loading . 15
5.3.1 General . 15
5.3.2 Design by formula (DBF) . 15
5.3.3 Design by analysis (DBA). 16
5.3.4 Design by experiment (DBE) . 16
5.4 Temperature reduction factor . 16
5.5 Wall thickness correction factor . 16
5.6 Design for external pressure . 17
5.7 Testing conditions . 17
5.8 Design methods . 17
5.8.1 General . 17
5.8.2 Static loading . 17
5.8.3 Dynamic loading . 20
5.9 Construction details . 25
5.9.1 Reinforcement of openings in cylinders, flat ends, dished ends, etc. . 25
5.9.2 Fillet radius . 25
5.9.3 Dished cover . 26
5.10 Technical documentation . 26
5.10.1 General . 26
5.10.2 Information to be contained in the technical documentation . 26
5.10.3 Test reports . 28
5.10.4 Design review . 28
6 Founding, material and casting testing . 29
6.1 Founding . 29
6.1.1 General . 29
6.1.2 Welding . 29
6.2 Material testing . 29
6.2.1 General . 29
6.2.2 Frequency and number of tests . 29
2

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SIST EN 15776:2022
EN 15776:2022 (E)
6.2.3 Inspection documents . 30
6.3 Casting testing . 30
6.3.1 General . 30
6.3.2 Surface imperfections . 30
6.3.3 Cracks, laps, cold shot and non-fused chaplets . 30
6.3.4 Ultrasonic testing and/or sectioning . 30
6.3.5 Liquid penetrant testing . 31
6.3.6 Surface roughness . 31
6.3.7 Minimum wall thickness . 31
6.3.8 Wall thickness tolerances . 31
6.3.9 Other dimensions . 31
6.3.10 Qualification of testing personnel . 31
7 Final assessment . 31
7.1 General . 31
7.2 Hydraulic test pressure . 31
8 Pressure vessels assembled of a combination of parts in different materials . 32
9 Marking and documentation . 32
9.1 Marking of castings . 32
9.2 Name plate for the complete pressure vessel . 32
9.3 Documentation . 32
Annex A (informative) Technical data for design calculations . 33
Annex B (informative) Recommendations for in-service validation and inspection . 36
B.1 Purpose . 36
B.2 Tests during operation . 36
Annex C (informative) Examples of fatigue design curves . 37
Annex ZA (informative) Relationship between this European standard and the essential
requirements of Directive 2014/68 EU aimed to be covered . 40
Bibliography . 41

3

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SIST EN 15776:2022
EN 15776:2022 (E)
European foreword
This document (EN 15776:2022) has been prepared by Technical Committee CEN/TC 54 “Unfired
pressure vessels”, the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2023, and conflicting national standards shall
be withdrawn at the latest by January 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 15776:2011+A1:2015.
Compared to the previous edition EN 15776:2011+A1:2015, the following changes have been made:
— clarifications to a number of the formulaes and tables;
— update of references.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association, and supports essential requirements of EU
Directive(s) / Regulation(s).
For relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, which is an integral
part of this document.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations 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.

4

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SIST EN 15776:2022
EN 15776:2022 (E)
Introduction
This document is a stand-alone document and may be used for cast iron pressure equipment with
certain restrictions and limitations.
Attention is drawn to the references to EN 13445-6:2021 for design and fabrication according to
specific grades of material standards EN 1563:2018 and EN 13835:2012 which are found in some
clauses of this document, EN 15776:2022. Requirements for the design, material, manufacturing and
testing of pressure vessels and pressure vessel parts made from ferritic or austenitic spheroidal
graphite cast iron grades with an elongation after fracture higher than 15 % are given in
EN 13445-6:2021.
Cast iron with elongation after fracture equal or less than 15 % may only be used for pressure
equipment when operational and technical advantages are indicating its use instead of the cast iron
grades given in EN 13445-6:2021 with elongation after fracture higher than 15 %.
NOTE For the design and fabrication of cast iron pressure equipment standards with higher elongations and
ductility, see EN 13445-6:2021.

5

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SIST EN 15776:2022
EN 15776:2022 (E)
1 Scope
This document specifies requirements for the design, material, manufacturing and testing of cast iron
pressure vessels and pressure vessel parts made from materials for which details are specified from the
following material standards for specific grades which meet the criterion of an elongation after fracture
less than or equal to 15 %:
— EN 1561:2011, Founding — Grey cast irons;
— EN 1563:2018, Founding — Spheroidal graphite cast irons;
— EN 13835:2012, Founding — Austenitic cast irons.
The application of this document is limited to pressure equipment and pressure parts containing a fluid
of group 2 (non-hazardous fluid) according to the European legislation for pressure equipment.
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.
EN 764-5:2014, Pressure equipment — Part 5: Inspection documentation of metallic materials and
compliance with the material specification
EN 1370:2011, Founding — Examination of surface condition
EN 1371-1:2011, Founding — Liquid penetrant testing— Part 1: Sand, gravity die and low pressure die
castings
EN 1559-1:2011, Founding — Technical conditions of delivery — Part 1: General
EN 1559-3:2011, Founding — Technical conditions of delivery — Part 3: Additional requirements for iron
castings
EN 1561:2011, Founding — Grey cast irons
EN 1563:2018, Founding — Spheroidal graphite cast irons
EN 12680-3:2011, Founding — Ultrasonic testing — Part 3: Spheroidal graphite cast iron castings
EN 13445-3:2021, Unfired pressure vessels — Part 3: Design
EN 13445-5:2021, Unfired pressure vessels — Part 5: Inspection and testing
EN 13445-6:2021, Unfired pressure vessels — Part 6: Requirements for the design and fabrication of
pressure vessels and pressure parts constructed from spheroidal graphite cast iron
EN 13835:2012, Founding — Austenitic cast irons
EN ISO 8062-3:2007, Geometrical Product Specifications (GPS) — Dimensional and geometrical
tolerances for moulded parts — Part 3: General dimensional and geometrical tolerances and machining
allowances for castings (ISO 8062-3:2007)
6

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SIST EN 15776:2022
EN 15776:2022 (E)
3 Terms, definitions, units and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
grey cast iron
cast material, mainly iron and carbon based, carbon being present mainly in the form of flake (lamellar)
graphite particles
Note 1 to entry: Grey cast iron is also known as flake graphite cast iron, and less commonly as lamellar graphite
cast iron.
Note 2 to entry: Grey cast irons contain 2,0 % - 4,5 % carbon and 1 % - 3 % silicon. The structure consists of
branched and interconnected graphite flakes in a matrix which is pearlite, ferrite or a mixture.
[SOURCE: EN 1561:2011, 3.1, modified — The content of Note 2 to entry was changed.]
3.1.2
spheroidal graphite cast iron
cast material, mainly iron and carbon-based, the carbon being present mainly in the form of spheroidal
graphite particles
Note 1 to entry: Spheroidal graphite cast iron is also known as ductile iron, and less commonly as nodular iron.
Note 2 to entry: The mechanical properties of grey irons can be greatly improved if the graphite shape is
modified if molten iron, having a composition in the range 3,2 % - 4,5 % carbon and 1,8 % - 2,8 % silicon, is
treated with magnesium. This produces castings with graphite in spheroidal form instead of flakes, known as
nodular, spheroidal graphite or ductile iron. Nodular irons are available with pearlite, ferrite or pearlite-ferrite
matrices which offer a combination of greater ductility and higher tensile strength than grey cast irons.
[SOURCE: EN 1563:2018, 3.1, modified — The start of the definition was altered and Note 2 to entry
was added.]
3.1.3
austenitic cast iron
cast material with an austenitic matrix which is iron and carbon and silicon based and alloyed with
nickel and manganese, copper and/or chromium in order to stabilize the austenitic structure at room
temperature
Note 1 to entry: The graphite can be present in flake or spheroidal form.
[SOURCE: EN 13835:2012, 3.1, modified — The start of the definition was altered and the final sentence
to the definition is now comprised in Note 1 to entry.]
7

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SIST EN 15776:2022
EN 15776:2022 (E)
3.1.4
relevant wall thickness
wall thickness representative of the casting defined for the determination of the size of the cast samples
to which the guaranteed mechanical properties apply
3.1.5
critical zone
highly stressed area where a fracture is expected to occur in a burst test
Note 1 to entry: It can be caused, for example, by any of the following:
— sudden change in cross section;
— sharp edges;
— sharp radii;
— peak stresses;
— bending stresses;
— stresses due to other than membrane stress;
— changes in curvature.
Note 2 to entry: A critical zone is analysed by any appropriate method, e.g. holographic, interferometric method,
strain gauge methods, burst test, fatigue testing, FEM analysis, etc.
Note 3 to entry: Additionally, thermal gradients and thermal stresses due to different operating wall
temperatures are to be considered in defining critical zones.
3.1.6
purchaser
individual or organization that buys pressure equipment, including assemblies or parts, for its own use
or on behalf of the user and/or operator
3.1.7
manufacturer
individual or organization responsible for the design, fabrication, testing, inspection, installation of
pressure equipment and assemblies where relevant
Note 1 to entry: The manufacturer may subcontract one or more of the above-mentioned tasks under its
responsibility.
3.1.8
casting manufacturer
subcontractor that produces the castings used in the manufacture of pressure equipment
3.1.9
temperature factor
reduction factor applied to the 0,2 % proof strength to take account of temperature influence
3.1.10
thickness factor
factor applied to the nominal design stress to take account of reduced mechanical properties
8

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SIST EN 15776:2022
EN 15776:2022 (E)
3.1.11
stress factor
factor for the determination of the maximum structural stress that may occur in a vessel detail, due to
the geometrical configuration of component(s)
[SOURCE: EN 13445-3:2021, 17.2.3]
3.1.12
total stress
total stress in a design model which includes all stress concentration effects, non-local and local
3.2 Symbols
For the purposes of this document, symbols used in EN 13445-6:2021 are listed in Table 1.
Table 1 — Symbols
Symbol Quantity Unit
c corrosion allowance mm
e required thickness mm
e analysis thickness mm
a
e actual thickness mm
act
maximum local thickness at the location of a possible fatigue
e mm
max
crack initiation
e minimum thickness as specified on drawing mm
min
f nominal design stress MPa
f thickness correction factor
e
f mean stress correction factor
m
f nominal design stress for testing condition MPa
test
f temperature correction factor
T
f surface finish correction factor
s
m exponent in equation of fatigue design curve
C
n factor depending on shape of shell
n number of equivalent full pressure cycles
eq
T calculation temperature °C
A, A minimum elongation after fracture %
5
C coefficient in equation of fatigue design curve
C
Ce wall thickness factor
C temperature factor
T
E modulus of elasticity MPa
F fatigue factor related to 99,8 % survival
K effective stress concentration factor
eff
9

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SIST EN 15776:2022
EN 15776:2022 (E)
Symbol Quantity Unit
K theoretical elastic stress concentration factor
t
M mean stress sensitivity factor MPa
value from appropriate Tables 10, 11, 13, 14 in the appropriate
m
c
number of cycle number range used in fatigue calculations
total number of envisaged types of pressure cycles with
N
different amplitude
allowable number of cycles obtained from the fatigue design
N
all
curve
minimum number of cycles obtained in experimental fatigue
N
min
assessment
n number of cycles with amplitude ΔPi
i

a
P minimum required bursting pressure MPa
b
a
P , actual burst test pressure MPa
b act
a
P design pressure MPa
d
b a
P maximum permissible pressure MPa
max
b a
PS, P maximum allowable pressure bar
s
b
PT, p test pressure MPa
t
R tensile strength MPa
m
R minimum 0,2 % - proof strength MPa
p0,2
minimum 0,2 % - proof strength at temperature T in degrees
Rp0,2/T MPa
Celsius
R surface roughness parameter – peak – to - valley height µm
z
R material strength parameter MPa
M
RM3 average strength from 3 tensile test samples MPa
S safety factor
TS , TS maximum / minimum allowable temperature °C
max min
V volume L
a
ΔP pressure range MPa
ΔP pressure cycle amplitude
i
Δσ allowable stress range MPa
Δσ* pseudo elastic stress range MPa
Δσ cut-off limit MPa
Cut
Δσ endurance limit MPa
D
Δσ structural stress range MPa
eq,struc
Δσ stress range in fatigue design curve MPa
R
10

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SIST EN 15776:2022
EN 15776:2022 (E)
Symbol Quantity Unit
δ casting tolerance mm
ε extra thickness due to casting process mm
γ partial safety factor
R
η
stress factor
ν Poisson’s ratio
σ nominal design stress for external pressure MPa
e
a
MPa for calculation purposes only, otherwise the unit shall be bar (1 MPa = 10 bar).
b
See also EN 13445-3:2021, Table 4–1.

3.3 Inter relation of thicknesses definitions (EN 13445-6:2021)

Key
e required thickness
e analysis thickness
a
emin minimum thickness including corrosion allowance as indicated on drawings
eact actual thickness
c corrosion allowance
ε extra thickness due to casting process
δ casting tolerance
Figure 1 — Inter-relation of thicknesses definitions
4 Materials, limitations and service conditions
4.1 Materials and limitations on temperature, maximum allowable pressure and energy
content
All material grades subject to internal or external pressure shall comply with EN 1561:2011 for grey
cast iron, EN 1563:2018 for spheroidal graphite cast iron and EN 13835:2012 for austenitic cast iron.
The material grades and corresponding limitations are given in Table 2 and Table 3.
11

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SIST EN 15776:2022
EN 15776:2022 (E)
Table 2 — Allowable material grades and limitations for grey cast iron and austenitic lamellar
graphite cast iron
Maximum Maximum
Material Material designation Design
standard temperature allowable energy content
range pressure PS PS × V for a
single casting
TS / TS
min max
Symbol Number °C bar bar ⋅ L
EN-GJL-200 5.1000
−10 ≤ T ≤ 200
EN-GJL-250 5.1301
EN 1561:2011
EN-GJL-300 5.1302 25 65 000
−10 ≤ T ≤ 200
EN-GJL-350 5.1303
EN 13835:2012 EN-GJLA-XNiCuCr15–6-2 5.1500 −10 ≤ T ≤ 200

The product PS × V, and the design temperature range of Table 2 for a single casting may be exceeded
only for material grades EN-GJL-300 and EN-GJL-350 up to 300 °C and a product PS × V, as appropriate,
when all the following conditions a
...

SLOVENSKI STANDARD
oSIST prEN 15776:2019
01-januar-2019
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Unfired pressure vessels - Requirements for the design and fabrication of pressure
vessels and pressure parts constructed from cast iron with an elongation after fracture
equal or less than 15 %
Unbefeuerte Druckbehälter - Anforderungen an die Konstruktion und Herstellung von
Druckbehältern und Druckbehälterteilen aus Gusseisen mit einer Bruchdehnung von 15
% oder weniger
Récipients sous pression non soumis à la flamme - Exigences pour la conception et la
fabrication des récipients et parties sous pression moulés en fonte à allongement, après
rupture, inférieur ou égal à 15 %
Ta slovenski standard je istoveten z: prEN 15776
ICS:
23.020.32 7ODþQHSRVRGH Pressure vessels
77.140.80 Železni in jekleni ulitki Iron and steel castings
oSIST prEN 15776:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 15776:2019

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oSIST prEN 15776:2019


DRAFT
EUROPEAN STANDARD
prEN 15776
NORME EUROPÉENNE

EUROPÄISCHE NORM

January 2019
ICS 23.020.30 Will supersede EN 15776:2011+A1:2015
English Version

Unfired pressure vessels - Requirements for the design
and fabrication of pressure vessels and pressure vessel
parts constructed from cast iron with an elongation after
fracture equal or less than 15 %
Récipients sous pression non soumis à la flamme - Unbefeuerte Druckbehälter - Anforderungen an die
Exigences pour la conception et la fabrication des Konstruktion und Herstellung von Druckbehältern und
récipients et parties sous pression moulés en fonte à Druckbehälterteilen aus Gusseisen mit einer
allongement, après rupture, inférieur ou égal à 15 % Bruchdehnung von 15 % oder weniger
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 54.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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,
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Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.


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. prEN 15776:2019 E
worldwide for CEN national Members.

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Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, units and symbols . 7
3.1 Terms and definitions . 7
3.2 Symbols . 9
3.3 Inter relation of thicknesses definitions (EN 13445-6:2014) . 11
4 Materials, limitations and service conditions. 11
4.1 Materials and limitations on temperature, maximum allowable pressure and energy
content . 11
4.2 Cyclic loading . 13
5 Design requirements . 14
5.1 Design principle . 14
5.2 Conceptual design and construction drawings . 15
5.3 Static loading . 15
5.3.1 General . 15
5.3.2 Design by formula (DBF) . 15
5.3.3 Design by analysis (DBA). 16
5.3.4 Design by experiment (DBE) . 16
5.4 Temperature reduction factor . 16
5.5 Wall thickness reduction factor . 16
5.6 Design for external pressure . 17
5.7 Testing conditions . 17
5.8 Design methods . 17
5.8.1 General . 17
5.8.2 Static loading . 17
5.8.3 Dynamic loading . 20
5.9 Construction details . 25
5.9.1 Reinforcement of openings in cylinders, flat ends, dished ends, etc. . 25
5.9.2 Fillet radius . 25
5.9.3 Dished cover . 25
5.10 Technical documentation . 26
5.10.1 General . 26
5.10.2 Information to be contained in the technical documentation . 26
5.10.3 Test reports . 28
5.10.4 Design review . 28
6 Founding, material and casting testing . 29
6.1 Founding . 29
6.1.1 General . 29
6.1.2 Welding . 29
6.2 Material testing . 29
6.2.1 General . 29
6.2.2 Frequency and number of tests . 29
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6.2.3 Inspection documents . 29
6.3 Casting testing . 29
6.3.1 General . 29
6.3.2 Surface imperfections . 30
6.3.3 Cracks, laps, cold shot and non-fused chaplets . 30
6.3.4 Ultrasonic testing and/or sectioning . 30
6.3.5 Liquid penetrant testing . 30
6.3.6 Surface roughness . 31
6.3.7 Minimum wall thickness . 31
6.3.8 Wall thickness tolerances . 31
6.3.9 Other dimensions . 31
6.3.10 Qualification of testing personnel . 31
7 Final assessment . 31
7.1 General . 31
7.2 Hydraulic test pressure . 31
8 Pressure vessels assembled of a combination of parts in different materials . 32
9 Marking and documentation . 32
9.1 Marking of castings . 32
9.2 Name plate for the complete pressure vessel . 32
9.3 Documentation . 32
Annex A (informative) Technical data for design calculations . 33
Annex B (informative) Recommendations for in-service validation and inspection . 36
B.1 Purpose . 36
B.2 Tests during operation . 36
Annex C (informative) Examples of fatigue design curves . 37
Annex ZA (informative) Relationship between this European standard and the essential
requirements of Directive 2014/68 EU aimed to be covered . 40
Bibliography . 41

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European foreword
This document (prEN 15776:2019) has been prepared by Technical Committee CEN/TC 54 “Unfired
pressure vessels”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 15776:2011+A1:2015.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive 2014/68/EU.
For relationship with EU Directive 2014/68/EU, see informative Annex ZA, which is an integral part of
this document.
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Introduction
This standard is a stand-alone document and may be used for pressure equipment with certain
restrictions and limitations.
NOTE For the design and fabrication of cast iron pressure equipment standards with higher elongations and
ductility, see EN 13445-6:2014.
Attention is drawn to the references to EN 13445-6:2014 for design and fabrication according to
specific grades of material standards EN 1563:2018 and EN 13835:2012 which are found in some
clauses of this document, prEN 15776. Requirements for the design, material, manufacturing and
testing of pressure vessels and pressure vessel parts made from ferritic or austenitic spheroidal
graphite cast iron grades with an elongation after fracture higher than 15 % are given in
EN 13445-6:2014.
Cast iron with elongation after fracture equal or less than 15 % may only be used for pressure
equipment when operational and technical advantages are dictating its use instead of the cast iron
grades given in EN 13445-6:2014 with elongation after fracture higher than 15 %.
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1 Scope
This document specifies requirements for the design, material, manufacturing and testing of pressure
vessels and pressure vessel parts made from materials for which details are specified from the
following material standards for specific grades which meet the criterion of an elongation after fracture
less than or equal to 15 %:
— EN 1561:2011, Founding — Grey cast irons;
— EN 1563:2018, Founding — Spheroidal graphite cast irons;
— EN 13835:2012, Founding — Austenitic cast irons.
NOTE The content of the vessel or pressure part is a fluid of group 2 only, according to
Directive 2014/68/EU.
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.
EN 764-5:2014, Pressure equipment – Part 5: Inspection documentation of metallic materials and
compliance with the material specification
EN 1370:2011, Founding - Examination of surface condition
EN 1371-1:2011, Founding - Liquid penetrant testing- Part 1: Sand, gravity die and low pressure die
castings
EN 1559-1:2011, Founding - Technical conditions of delivery – Part 1: General
EN 1559-3:2011, Founding – Technical conditions of delivery – Part 3: Additional requirements for iron
castings
EN 1561:2011, Founding – Grey cast irons
EN 1563:2018, Founding – Spheroidal graphite cast irons
EN 12680-3:2011, Founding – Ultrasonic testing – Part 3: Spheroidal graphite cast iron castings
EN 13445-3:2014, Unfired pressure vessels – Part 3: Design
EN 13445-5:2014, Unfired pressure vessels – Part 5: Inspection and testing
EN 13445-6:2014, Unfired pressure vessels – Part 6: Requirements for the design and fabrication of
pressure vessels and pressure parts constructed from spheroidal graphite cast iron
EN 13835:2012, Founding – Austenitic cast irons
EN ISO 8062-3:2007, Geometrical Product Specifications (GPS) – Dimensional and geometrical tolerances
for moulded parts – Part 3: General dimensional and geometrical tolerances and machining allowances for
castings (ISO 8062-3:2007)
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3 Terms, definitions, units and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
grey cast iron
cast material, mainly iron and carbon based, carbon being present mainly in the form of flake (lamellar)
graphite particles
Note 1 to entry: Grey cast iron is also known as flake graphite cast iron, and less commonly as lamellar graphite
cast iron.
Note 2 to entry: Grey cast irons contain 2,0 % - 4,5 % carbon and 1 % - 3 % silicon. The structure consists of
branched and interconnected graphite flakes in a matrix which is pearlite, ferrite or a mixture.
[SOURCE: EN 1561:2011, 3.1, modified — The content of Note 2 to entry was changed.]
3.1.2
spheroidal graphite cast iron
cast material, mainly iron and carbon-based, the carbon being present mainly in the form of spheroidal
graphite particles
Note 1 to entry: Spheroidal graphite cast iron is also known as ductile iron, and less commonly as nodular iron.
Note 2 to entry: The mechanical properties of grey irons can be greatly improved if the graphite shape is
modified if molten iron, having a composition in the range 3,2 % - 4,5 % carbon and 1,8 % - 2,8 % silicon, is
treated with magnesium. This produces castings with graphite in spheroidal form instead of flakes, known as
nodular, spheroidal graphite or ductile iron. Nodular irons are available with pearlite, ferrite or pearlite-ferrite
matrices which offer a combination of greater ductility and higher tensile strength than grey cast irons.
[SOURCE: EN 1563:2018, 3.1, modified — The start of the definition was altered and Note 2 to entry
was added.]
3.1.3
austenitic cast iron
cast material with an austenitic matrix which is iron and carbon and silicon based and alloyed with
nickel and manganese, copper and/or chromium in order to stabilize the austenitic structure at room
temperature
Note 1 to entry: The graphite can be present in flake or spheroidal form.
[SOURCE: EN 13835:2012, 3.1, modified — The start of the definition was altered and the final sentence
to the definition is now comprised in Note 1 to entry.]
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3.1.4
relevant wall thickness
wall thickness representative of the casting defined for the determination of the size of the cast samples
to which the guaranteed mechanical properties apply
3.1.5
critical zone
highly stressed area where a fracture is expected to occur in a burst test
Note 1 to entry: It can be caused, for example, by any of the following:
— sudden change in cross section;
— sharp edges;
— sharp radii;
— peak stresses;
— bending stresses;
— stresses due to other than membrane stress;
— changes in curvature.
Note 2 to entry: A critical zone is analysed by any appropriate method, e.g. holographic, interferometric method,
strain gauge methods, burst test, fatigue testing, FEM analysis, etc.
Note 3 to entry: Additionally, thermal gradients and thermal stresses due to different operating wall
temperatures are to be considered in defining critical zones.
3.1.6
purchaser
individual or organization that buys pressure equipment, including assemblies or parts, for its own use
or on behalf of the user and/or operator
3.1.7
manufacturer
individual or organization responsible for the design, fabrication, testing, inspection, installation of
pressure equipment and assemblies where relevant
Note 1 to entry: The manufacturer may subcontract one or more of the above mentioned tasks under its
responsibility.
3.1.8
casting manufacturer
subcontractor that produces the castings used in the manufacture of pressure equipment
3.1.9
temperature factor
reduction factor applied to the 0,2 % proof strength to take account of temperature influence
3.1.10
wall thickness factor
reduction factor applied to the nominal design stress to take account of reduced mechanical properties
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3.1.11
stress factor
ratio of peak stress to total stress
3.1.12
total stress
total stress in a design model which includes all stress concentration effects, non-local and local
3.2 Symbols
For the purposes of this document, symbols used in EN 13445-6:2014 are listed in Table 1.
Table 1 — Symbols
Symbol Quantity Unit
c corrosion allowance mm
e required thickness mm
e analysis thickness mm
a
e actual thickness mm
act
maximum local thickness at the location of a possible fatigue
e mm
max
crack initiation
e minimum thickness as specified on drawing mm
min
f nominal design stress MPa
f thickness correction factor
e
f mean stress correction factor
m
f nominal design stress for testing condition MPa
test
f temperature correction factor
T
f surface finish correction factor
s
m exponent in equation of fatigue design curve
C
n shell shape factor
n number of equivalent full pressure cycles
eq
T,T calculation temperature °C
c
A, A minimum elongation after fracture %
5
C coefficient in equation of fatigue design curve
C
C wall thickness reduction factor
e
C temperature reduction factor
T
E modulus of elasticity MPa
F test factor used in experimental fatigue assessment
K effective stress concentration factor
eff
K theoretical elastic stress concentration factor
t
M mean stress sensitivity factor MPa
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Symbol Quantity Unit
value from appropriate Tables 10, 11, 13, 14 in the appropriate
m
c
number of cycle number range used in fatigue calculations
total number of envisaged types of pressure cycles with
N
different amplitude
allowable number of cycles obtained from the fatigue design
N
all
curve
minimum number of cycles obtained in experimental fatigue
N
min
assessment
n number of cycles with amplitude ΔPi
i
a
PC,p calculation pressure MPa
c
a
P burst test pressure MPa
b
a
P , actual burst test pressure MPa
b act
a
PD,p design pressure MPa
d
b a
P maximum permissible pressure MPa
max
b a
PS,p maximum allowable pressure bar
s
b
PT, p test pressure MPa
t
R minimum tensile strength MPa
m
R minimum 0,2 % - proof strength MPa
p0,2
minimum 0,2 % - proof strength at temperature T in degrees
Rp MPa
0,2/T
Celsius
R surface roughness parameter – peak – to - valley height µm
z
R material strength parameter MPa
M
RM3 average strength from 3 tensile test samples MPa
S safety factor
TS , TS maximum / minimum allowable temperature °C
max min
V volume L
a
ΔP pressure range MPa
ΔP pressure cycle amplitude
i
Δσ allowable stress range MPa
Δσ* pseudo elastic stress range MPa
Δσ cut-off limit MPa
Cut
Δσ endurance limit MPa
D
Δσ structural stress range MPa
eq,struc
Δσ stress range in fatigue design curve MPa
R
δ casting tolerance mm
ε extra thickness due to casting process mm
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Symbol Quantity Unit
γ partial safety factor
R
η
Stress factor
ν Poisson’s ratio
σ nominal design stress for external pressure MPa
e
a
 MPa for calculation purposes only, otherwise the unit shall be bar (1 MPa = 10 bar).
b
 See also EN 13445-3:2014, Table 4–1.

3.3 Inter relation of thicknesses definitions (EN 13445-6:2014)

Key
e required thickness
ea analysis thickness
e minimum thickness including corrosion allowance as indicated on drawings
min
eact actual thickness
c corrosion allowance
ε extra thickness due to casting process
δ casting tolerance
Figure 1 — Inter-relation of thicknesses definitions
4 Materials, limitations and service conditions
4.1 Materials and limitations on temperature, maximum allowable pressure and energy
content
All material grades subject to internal or external pressure shall comply with EN 1561:2011 for grey
cast iron, EN 1563:2018 for spheroidal graphite cast iron and EN 13835:2012 for austenitic cast iron.
The material grades and corresponding limitations are given in Table 2 and Table 3.
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Table 2 — Allowable material grades and limitations for grey cast iron and austenitic lamellar
graphite cast iron
Design Maximum Maximum
Material Material designation
standard temperature allowable energy content
range pressure PS PS × V for a
single casting
TS /TS
min max
Symbol Number °C bar bar ⋅ L
EN-GJL-200 5.1000
−10 ≤ T ≤ 200
EN-GJL-250 5.1301
EN 1561:2011
EN-GJL-300 5.1302 25 65 000
−10 ≤ T ≤ 200
EN-GJL-350 5.1303
EN 13835:2012 EN-GJLA-XNiCuCr15–6-2 5.1500 −10 ≤ T ≤ 200

The product PS × V, and the design temperature range of Table 2 for a single casting may be exceeded
only for material grades EN-GJL-300) and EN-GJL-350) up to 300 °C and a product PS × V, as
appropriate, when all the following conditions are met:
— maximum allowable temperature TS ≤ 300 °C;
max
— maximum allowable pressure lowered from 25 bar to PS ≤ 15 bar;
— documented stress factor ≤ 2 throughout the casting;
— stress relief heat treatment is carried out when the maximum cooling rate in the mould exceeds
30 °C/h for the temperature range from 600 °C decreasing to 150 °C.
An in-service inspection to Annex B of this standard may be considered to be mentioned in the
operating instructions of the part or vessel.
The requirements of material grade EN-GJL-350 in this clause may allow the fabrication of paper
cylinder and dryer rollers.
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Table 3 — Allowable material grades and design limits for spheroidal graphite cast iron
Material Material designation Design Maximum Maximum
temperature allowable energy content
standard
range pressure PS × V for a
single casting
TS /TS PS
min max
bar ⋅ L
Symbol Number °C bar
EN-GJS-400–
5.3106 100 100 000
15
EN-GJS-450–
5.3107
10
64 80 000
EN 1563:2018 - 10 ≤ TS ≤ 300
EN-GJS-500–7 5.3200
...

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