SIST EN 15776:2022
(Main)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 %
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 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.
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
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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.
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
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
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.
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.
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)
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.]
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
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 %
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
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
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.
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 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 document may 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.
Table 3 — Allowable material grades and design limits for spheroidal graphite cast iron
Material Material designation Design Maximum Maximum
allowable energy content
standard temperature
range pressure PS × V for a
single casting
TS / TS PS
min max
bar ⋅ L
Symbol Number °C bar
EN-GJS-400–15 5.3106 100 100 000
EN-GJS-450–10 5.3107
64 80 000
EN 1563:2018 EN-GJS-500–7 5.3200 - 10 ≤ TS ≤ 300
EN-GJS-600–3 5.3201
25 65 000
EN-GJS-700–2 5.3300
EN-GJSA-
5.3500
XNiCr20–2
EN-GJSA-
5.3502
XNiCrNb20–2
64 80 000
EN-GJSA-
5.3505
XNiSiCr35–5-2
EN 13835:2012 - 10 ≤ TS ≤ 540
EN-GJSA-
5.3507
XNiCr30–3
EN-GJSA-
5.3508 25 65 000
XNiSiCr30–5-5
EN-GJSA-
5.3509 64 80 000
XNiCr35–3
NOTE Whatever the used method the grades are based - on the mechanical properties from separately cast
samples in a sand mould or mould of comparable thermal diffusivity.
The applicable requirements for the delivery conditions, given in EN 1559-1:2011 and EN 1559-3:2011
shall also apply.
4.2 Cyclic loading
Lamellar and spheroidal graphite cast iron pressure vessels and vessel parts can be used for cyclic
operation. A fatigue analysis shall be performed if the service conditions require more than the
maximum number of full pressure cycles as given in Table 4, or more than an equivalent number of
cycles n with smaller amplitude according to Formula (1).
eq
Table 4 — Full pressure cycle number for dynamic loading consideration
Material grade Maximum number of full pressure cycles without
mandatory fatigue analysis according to Formula (1)
(if stress factor η ≤ 3)
Grades according to Table 2 8 000
Grades according to Table 3 50 000
The calculation of an equivalent number of full pressure cycles n when the operating pressure is less
eq
than the maximum pressure shall be calculated according to Formula (1):
m
c
jN−
∆P
i
nn⋅ (1)
∑
eq j
P
max
j−1
where
N is the total number of envisaged types of pressure cycles with different amplitude;
n is the number of cycles with amplitude ΔP ;
j i
is the pressure cycle amplitude;
∆P
i
is the maximum permissible pressure, as defined in EN 13445-3:2021, 3.16;
P
max
m is the value from Table 10 (lamellar graphite cast iron grades) or Table 11 (spheroidal
C
graphite cast iron grades) in the appropriate number of cycle range value for
3 6 6 8
10 < N < 10 or 10 < N < 10 whichever is the case.
A stress factor – defined in 3.1.11 greater than 3, determined by any of the design methods given in 5.8,
can be the result of inappropriate design. By enlarging radii or other small changes, an acceptable
design may be generated. It is recommended to carry out a finite element analysis to determine areas
with possible excessive stress concentrations. These areas may be also found in feets, supports, lifting
lugs, etc. which may influence stress distribution in the pressure part.
5 Design requirements
5.1 Design principle
The loadings to be accounted for shall be in accordance with EN 13445-3:2021, Clause 5.
The materials, limitations and service conditions of Clause 4 of this document shall be considered.
Design methods shall be in accordance with this European standard and, when indicated in a clause of
this document, with the relevant clauses of EN 13445-6:2021.
If the geometry of the component or the loading case does not allow calculation by the formulas given in
EN 13445-3:2021, design by analysis (DBA) or design by experiment (DBE) shall be applied.
Depending on the complexity of the component, the loading conditions and the level of NDT, the
designer may choose one of the following available design methods mentioned below. Correlation
between safety factor, testing factor and the method to assess dynamic loading is given in Table 5.
=
5.2 Conceptual design and construction drawings
The manufacturer analysis of hazards identifying those which apply to the pressure vessel on account of
pressure shall be documented and be of sufficient detail.
Details of the conceptual design including the design methods adopted, performance criteria and
construction drawings shall be provided. Guidance about the detailed dimensional information that
shall be provided is given in EN 13445-5:2021, Annex B. Process diagrams, sub-assemblies or other
data relevant to conceptual design shall also be maintained.
5.3 Static loading
5.3.1 General
In order to design the part for static loading, the following shall be considered by the designer.
5.3.2 Design by formula (DBF)
Formulae for the calculation of the various components of the pressure part are given in
EN 13445-3:2021 and EN 13445-6:2021, Annex G. This Annex G gives additional formulae for non-
standard shaped parts often used in casting design. Nominal design stress for component forms other
than bolts shall be calculated in accordance with Table 5. If design by experimental method is used, it
shall be in conformity with 5.3.4 of this document. In general, the manufacturer shall specify to the
casting manufacturer which zones are critical related to the design and design loads. Other critical
zones may be indicated by the casting manufacturer related to the casting process and shall be taken
into account by the manufacturer.
Table 5 — Safety factor and nominal design stress
Item Material grades according to Material grades according to Table 2
Table 3
Stress
Grade
As cast relieve
according to
annealed
EN 1561:2011 S = 9 S = 7
S=3,,75+−0 5 1
Safety factor S
A
a
EN 13835:2012 S = 8 S = 6
R ⋅⋅C C
R
Nominal design
p0,2 Te
m
f =
f =
stress f
S
S
where
C is defined in 5.4;
T
C is defined in 5.5;
e
R is the tensile strength value for a given wall thickness according to Table A.1;
m
R is 0,2 % proof strength value according to Table A.4
p0,
where A is the elongation after fracture in percent according to EN 1563:2018 and EN 13835:2012.
a
If a risk of stress corrosion cracking may exist, especially for austenitic grades at higher temperatures, a stress
relief heat treatment is beneficial depending on the service conditions but is left to the agreement between the
parties concerned.
5.3.3 Design by analysis (DBA)
a) Use the stress categorization method (EN 13445-3:2021, Annex C);
b) base modelling and interpretation of calculation results shall be based on analysis thickness (e )
a
and material characteristics at operation temperature;
c) for interpretation of calculation results, follow the evaluation procedures and assessment criteria in
order to evaluate the fitness for purpose of the real structure. These design checks and related
procedures are typical for the failure mode to be dealt with. For the different failure modes, see
EN 13445-3:2021.
5.3.4 Design by experiment (DBE)
Where design by formulae (DBF) according to EN 13445-3:2021 is not considered appropriate due to
the complex shape of the component, then a hydraulic burst test to determine the analysis thickness e
a
and the minimum thickness e shall be performed according to the procedure in 5.8.2.4. This test is
min
also a part of the technical documentation.
For vessels for which PS × V < 6 000 bar × L (600 MPa × L) an experimental method may be applied as
an alternative to the design by formulae (DBF) or design by analysis (DBA) methods.
For vessels for which PS × V ≥ 6 000 bar × L (600 MPa × L) the experimental method may be used in
addition to calculated method design.
5.4 Temperature reduction factor
For grey cast iron material grades according to EN 1561:2011 and austenitic lamellar graphite cast iron
material grades according to EN 13835:2012 mechanical properties shall be considered to remain
constant for the temperature range −10 °C up to 200 °C.
For spheroidal graphite cast iron material grades according to EN 1563:2018:
C = 1 for T ≤ 20 °C (2)
T
C = 1 – 0,001(T - 20) for 20 °C < T ≤ 300 °C (3)
T
For austenitic spheroidal graphite cast iron material grades according to EN 13835:2012:
CT = 1 for T ≤ 20 °C (4)
C = 1 – 0,000 5 (T - 20) for 20 °C < T ≤ 540 °C (5)
T
5.5 Wall thickness correction factor
For spheroidal graphite cast iron material grades according to EN 1563:2018 and EN 13835:2012:
C = 1 for e ≤ 60 mm (6)
e min
C = 0,8 for 60 mm < e ≤ 200 mm (7)
e min
NOTE The wall thickness correction factor for lamellar graphite cast iron grades according to EN 1561:2011
is already included in Table A.1 in this document and needs no extra thickness correction factor.
See Bibliography ref. [13].
5.6 Design for external pressure
Design for external pressure shall be carried out according to EN 13445-3:2021, Clause 8, with the
following modifications:
Replace Formulae (8.4.2-1), (8.4.2-2), (8.4.3-1), (8.4.3-2) by:
σ RC⋅ (8)
e p0,/2 Te
The minimum safety factor, which applies throughout this clause, is given by:
— for material grades according to Table 2:
S = (safety factor according to Table 5) + 1 (9)
— for material grades according to Table 3:
S = (safety factor according to Table 5) + 0,5 (10)
5.7 Testing conditions
The test pressure may exceed the value given in Formula (15) either intentionally or occasionally.
However, the nominal design stress for testing conditions, f shall not exceed the following values.
test
For material grades according to Table 2:
R
m
f = (11)
test
For material grades according to Table 3:
RC⋅
pe0,/2 Ttest
f = (12)
test
1,33
5.8 Design methods
5.8.1 General
Design methods shall be in accordance with this document and, when indicated in the clauses of this
document, with the clauses of EN 13445-6:2021.
5.8.2 Static loading
5.8.2.1 General
In order to design the part for static loading, the following options can be considered by the designer.
5.8.2.2 Design by formula (DBF)
Formulas for the calculation of the various components of the pressure part are given in
EN 13445-3:2021.
5.8.2.3 Design by analysis (DBA)
For cast iron pressure vessels the general procedures and corresponding rules are covered by
EN 13445-6:2021, Annex E “Design by analysis for castings” with the following modifications:
=
— additional to EN 13445-6:2021, E.2.1 “Design checks for normal operating load cases”:
Material strength parameters (RM) and partial safety factors (γ ) shall be as given in Table 6:
R
Table 6 — RM and γR for normal operating load cases
Material grade RM γ
R
a
According to Table 2 R S/1,8
m
a
According to Table 3 R S/(1,8 × C )
p0,2/T e
a
S according to Table 5.
— additional to EN 13445-6:2021, E.2.2 “Design checks for testing load cases”:
RM and γ shall be as given in Table 7 and Table 8:
R
Table 7 — RM and γ for test load case lamellar cast iron grades
R
Material grade RM γ
R
According to Table 2 R 2,0
m
Table 8 — RM and γ for test load case spheroidal graphite cast iron grades
R
Material grade RM γ
R
According to Table 3 Rp0,2/Ttest 1,33/Ce
5.8.2.4 Design by experiment (DBE)
Design by experiment shall be carried out according to EN 13445-6:2021, 5.2.2.1.5, where:
— for material grades according to Table 2 of this document, the following formula applies:
12/
S ⋅ PS ⋅ RM3
(13)
ee ⋅
a act
PR⋅
b,act m
— for material grades according to Table 3 of this document, the following formula applies:
1/n
S ⋅ PS ⋅ R
m 3
( )
ee ⋅ (14)
a act
P ⋅ R ⋅⋅C C
b,,act p0 2 T e
where
n = 1 for curved surfaces (cylinders, spheres) or cones with angles α ≤ 60°, stayed surfaces and
stressed parts when it can be shown that the bending stress is less than 2/3 of the total
stress;
n = 2 for all other surfaces except when it can be shown that the bending stress is less than 2/3 of
the total stress.
=
=
5.8.2.5 RM3 Determination and general test requirements
For determining RM3 three tensile test specimen shall be performed in accordance with EN 1561:2011,
EN 1563:2018 or EN 13835:2012 material standards for each of the required positions taken from the
same cast.
The specimen positions shall be in accordance with the specifications in the technical delivery
conditions of the product form for materials for pressure equipment. In addition to the requirements of
the material, the manufacturer and the purchaser may agree on the properties required at stated
positions in the casting. These properties shall be determined by testing machined test pieces cut from
the casting at these stated positions. The mean value of the three specimens shall be used to determine
the average value of RM3.
Specimen may be taken before the burst test on an identical part or on the same part after burst test. It
is not allowed to use scaled-down part of the part under investigation. When taking values after burst
testing these may show lower tensile strength properties for some grades and should only be used with
caution in exceptional cases (single part or very large part, etc.).
The position on the casting from where the sample is cut shall be in an area where the casting wall
thickness is close to the relevant wall thickness of the casting. For determining the size of the test pieces
to be used, the purchaser shall, by the time of acceptance of the order, indicate to the manufacturer
which are the important sections. In the absence of any direction by the purchaser, the manufacturer
may choose the size of the test piece to be used according to the relevant standard.
No specimen may show a lower value than the minimum value of R stated in the respective material
m
standards of the material grade under investigation, taking into account the corresponding thickness.
The preferred test piece diameter is 14 mm, but, for te
...
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