EN 14917:2021

SLOVENSKI STANDARD
01-september-2021
Nadomešča:
SIST EN 14917:2009+A1:2012
Kompenzatorji s kovinskimi mehovi v tlačnih cevovodih
Metal bellows expansion joints for pressure applications
Kompensatoren mit metallischen Bälgen für Druckanwendungen
Compensateurs de dilatation à soufflets métalliques pour appareils à pression
Ta slovenski standard je istoveten z: EN 14917:2021
ICS:
23.040.99 Drugi sestavni deli za Other pipeline components
cevovode
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 14917
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2021
EUROPÄISCHE NORM
ICS 23.040.99 Supersedes EN 14917:2009+A1:2012
English Version
Metal bellows expansion joints for pressure applications
Compensateurs de dilatation à soufflets métalliques Kompensatoren mit metallischen Bälgen für
pour appareils à pression Druckanwendungen
This European Standard was approved by CEN on 21 June 2021.

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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14917:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 7
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 14
4 Classification . 17
4.1 Classification of expansion joints . 17
4.1.1 General . 17
4.1.2 Axial. 17
4.1.3 Angular . 17
4.1.4 Lateral . 17
4.1.5 Universal . 17
4.1.6 Pressure balanced designs (axial or universal) . 17
4.2 Classification of the parts of expansion joints . 20
4.2.1 Main pressure-bearing parts (A) . 20
4.2.2 Pressure parts other than main pressure-bearing parts (B) . 20
4.2.3 Attachments to main pressure-bearing parts and to pressure parts (C) . 20
4.2.4 Other parts (D) . 20
5 Materials . 22
5.1 General . 22
5.1.1 Materials for pressure-bearing parts . 22
5.1.2 Materials for parts attached to pressure-bearing parts. 22
5.1.3 Materials for non-pressure parts . 22
5.2 Pressure-bearing parts . 22
5.2.1 Bellows . 22
5.2.2 Other pressure-bearing parts . 22
5.2.3 Ductility . 23
5.2.4 Brittle fracture . 23
5.3 Material documentation . 27
6 Design . 28
6.1 General . 28
6.1.1 Symbols . 28
6.1.2 Basic design criteria . 34
6.1.3 Allowable stresses . 34
6.1.4 Additional loadings. 37
6.2 Bellows design . 38
6.2.1 Purpose . 38
6.2.2 Conditions of applicability . 38
6.2.3 Design of U-shaped unreinforced bellows . 56
6.2.4 Design of U-shaped reinforced bellows. 72
6.2.5 Design of toroidal bellows . 75
6.2.6 Fatigue . 82
6.2.7 Bellows under the influence of movements . 87
6.2.8 Equivalent axial displacement per corrugation . 92
6.2.9 Forces and moments on pressurized expansion joints . 97
6.2.10 Torsion acting on bellows (unreinforced or reinforced) . 108
6.3 Internal sleeve . 109
6.3.1 Scope . 109
6.3.2 Additional symbols . 109
6.3.3 Flow velocity . 109
6.3.4 Design conditions . 112
6.4 Hardware . 113
6.4.1 General . 113
6.4.2 Design parameters . 113
6.4.3 Hardware parts . 115
6.4.4 Permanent joints . 116
7 Manufacturing. 118
7.1 General . 118
7.2 Materials . 118
7.2.1 General . 118
7.2.2 Material traceability . 118
7.3 Permanent joints . 119
7.3.1 General . 119
7.3.2 Process and personal . 119
7.3.3 Repair and rework during manufacturing . 120
7.4 Forming of the bellows . 120
7.4.1 Forming processes . 120
7.4.2 Heat treatment. 121
7.5 Tolerances . 122
7.5.1 General . 122
7.5.2 Bellows . 122
7.5.3 Expansion joint . 123
7.6 Production tests . 123
8 Testing, inspection and documentation . 124
8.1 General . 124
8.2 Abbreviations . 124
8.3 Documents . 124
8.4 In-process inspection and testing . 125
8.4.1 General . 125
8.4.2 Materials . 125
8.4.3 Permanent joints . 125
8.4.4 Non-destructive testing of welds . 127
8.5 NDT methods . 134
8.5.1 Quality level . 134
8.5.2 Acceptance levels and testing techniques . 134
8.5.3 Non-destructive testing Personnel qualifications and approval . 135
8.5.4 Non-destructive testing documentation. 135
8.6 Final assessment and documentation . 137
8.6.1 General . 137
8.6.2 Final inspection . 138
8.7 Documentation . 140
8.7.1 Final documentation package . 140
8.7.2 Declaration/certification . 140
8.7.3 Operating instructions . 141
9 Marking and labelling . 141
10 Handling and installation . 141
10.1 General instructions . 141
10.2 Packaging and storage . 142
10.3 Installation . 142
10.4 Unrestrained expansion joints . 142
10.5 Restrained expansions joints . 142
Annex A (informative) Categories of expansion joints . 143
A.1 General . 143
A.2 Determination of expansion joints categories . 143
A.3 Fluid groups . 143
A.3.1 General . 143
A.3.2 Group 1. 143
A.3.3 Group 2. 144
A.4 Technical requirements. 144
A.4.1 Expansion joints for vessels . 144
A.4.2 Expansion joints for piping . 144
A.4.3 Sound engineering practice (SEP) . 145
A.5 Expansion joint category . 145
Annex B (informative) Specification for materials 1.4828, 1.4876, 2.4360 and 2.4858 . 147
Annex C (informative) Incorporation of expansion joints into piping or pressure vessels . 154
C.1 General . 154
C.2 Specific symbols and definitions . 155
C.3 Application criteria for expansion joints in piping . 156
C.3.1 General . 156
C.3.2 Use of axial expansion joints . 156
C.3.3 Use of restraint expansion joints . 162
C.3.4 Use of universal expansion joints . 168
C.3.5 Indeterminate configurations of expansion joints . 170
C.4 Application criteria for expansion joints in pressure vessels . 173
C.4.1 General . 173
C.4.2 Axial expansion joint installed in the shell . 173
C.4.3 Axial expansion joint installed at the floating head . 174
Annex D (informative) Calculation methods for systems of pipes containing expansion joints . 175
D.1 General . 175
D.1.1 Preliminary remarks . 175
D.1.2 Determining movement values . 175
D.1.3 Thermal expansion . 175
D.2 Approximate calculation of bellows movement . 177
D.2.1 General . 177
D.2.2 Hinged systems . 178
D.2.3 Definitions . 178
D.3 Exact calculation of bellows movement . 182
D.3.1 Two hinges in a plane system (Z-system) . 182
D.3.2 Two gimbals in a three-dimensional system (Z-system) . 183
D.3.3 Three hinges in a plane system (U-system) . 184
D.3.4 Three hinges in a plane system (L-system) . 185
D.3.5 Three hinges in a three-dimensional system (Z-system) . 187
D.4 Calculation of forces and moments . 190
Annex E (informative) Explanatory notes on the design of expansion bellows. 191
E.1 General . 191
E.2 Calculation design . 191
E.3 Types of bellows . 192
E.3.1 Corrugation shape. 192
E.3.2 Number of plies . 192
E.4 Fatigue life expectancy . 192
E.5 Instability . 193
E.5.1 General . 193
E.5.2 Column instability . 193
E.5.3 In-plane instability . 193
E.5.4 Buckling . 193
E.6 Bellows spring rate . 194
Annex F (informative) Procedure for setting-up a design fatigue curve . 196
F.1 General . 196
F.2 Procedure for setting up a design fatigue curve for expansion bellows. 196
F.2.1 General . 196
F.2.2 Number of tests . 196
F.2.3 Extrapolation range . 196
F.2.4 Manufacturing methods . 196
F.2.5 Bellows material . 197
F.3 Tests . 197
F.3.1 Movement . 197
F.3.2 Test pressure. 197
F.3.3 Other test conditions . 197
F.3.4 Fatigue test equipment . 198
F.4 Evaluation of the test results . 199
F.5 Linear regression . 204
Annex G (informative) Polynomial approximations for coefficients C , C , C . 205
p f d
G.1 Coefficient C . 205
p
G.2 Coefficient C . 206
f
G.3 Coefficient C . 207
d
G.4 Linear interpolation . 208
Annex H (informative) Required design data and information . 210
H.1 Required design conditions . 210
H.2 Additional information . 210
Annex I (informative) Expansion joints risk analyses . 211
Annex J (informative) Additional material properties. 212
Annex K (normative) Hardware calculation . 217
K.1 General . 217
K.2 Additional symbols . 217
K.3 Force due to pressure. 220
K.4 Tie bar . 221
K.4.1 General . 221
K.4.2 Tie bar in tension . 221
K.4.3 Tie bar in compression . 222
K.5 Pin . 222
K.6 Lug with bore . 225
K.6.1 General . 225
K.6.2 Forces due to pressure. 225
K.6.3 Stresses due to reaction force . 226
K.7 Gimbal, square and round . 227
K.7.1 General . 227
K.7.2 Stresses in bored section . 227
K.7.3 Square type gimbal. 228
K.7.4 Round type gimbal . 231
K.8 Attachment plate. 233
K.8.1 Attachment plate (closed/open) with 2 restraining parts . 233
K.8.2 Circular attachment plate with 3 or more tie bars valid up to DN 800 . 241
K.9 Lug-plate connection (hinge/gimbal) . 244
K.9.1 General . 244
K.9.2 Lug-plate for form-lock connection . 245
K.9.3 Lug-plate for welded buttonhole connection . 248
K.10 Tie bar and lug attachment on flanges . 249
K.10.1 Integral flange . 249
K.10.2 Plate welded on flange . 253
K.11 Gusset . 256
K.12 Gusset with reinforcing rings. 256
K.12.1 General . 256
K.12.2 Basic definitions . 258
K.12.3 Stresses in the gussets . 259
K.12.4 Stresses in the ring and pipe . 259
K.12.5 Stresses in welds a , a and a . 260
7 8 9
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2014/68/EU . 262
Bibliography . 264

European foreword
This document (EN 14917:2021) has been prepared by Technical Committee CEN/TC 342 “Metal hoses,
hose assemblies, bellows and expansion joints”, the secretariat of which is held by SNV.
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 2022, and conflicting national standards shall
be withdrawn at the latest by January 2022.
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 14917:2009+A1:2012.
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.
Modifications to EN 14917:2009+A1:2012:
— adaptation to Directive 2014/68/EU;
— general revision and correction;
— complete revision and restructuring of Clause 6, i.a.;
— addition of design in the creep range;
— modification of stress calculation for internal pressure capability;
— reformulation of column instability calculation;
— modification of in-plane instability calculation;
— harmonisation of fatigue calculation for all bellows types and introduction of 4 fatigue curves for
different material classes;
— extension of material characteristics for calculating forces and moments on pressurised
expansion joints;
— addition of Annex K for stress calculation of hardware;
— revision of Testing, inspection and documentation;
— revision of material properties in Annex B and Annex J;
— correction of Coefficient C .
p
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
Metal bellows expansion joints are used as parts in pressure vessels or piping components.
If an expansion joint is designed and manufactured covered by EU-Directive 2014/68/EU a risk
assessment has to be done. The possible risks of an expansion joint and how they have been dealt in this
document are described in Annex I.

1 Scope
This document specifies the requirements for design, manufacture and installation of metal bellows
expansion joints with circular cross section for pressure applications with maximum allowable pressure
greater than 0,5 bar.
2 Normative references
The following referenced documents are indispensable for the application 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 764-4:2014, Pressure equipment — Part 4: Establishment of technical delivery conditions for metallic
materials
EN 764-5:2014, Pressure equipment — Part 5: Inspection documentation of metallic materials and
compliance with the material specification
EN 1092-1:2018, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, PN
designated — Part 1: Steel flanges
EN 1591-1:2013, Flanges and their joints — Design rules for gasketed circular flange connections — Part 1:
Calculation
EN 1759-1:2004, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, Class
designated — Part 1: Steel flanges, NPS 1/2 to 24
EN 10028-1:2017, Flat products made of steels for pressure purposes — Part 1: General requirements
EN 10028-2:2017, Flat products made of steels for pressure purposes — Part 2: Non-alloy and alloy steels
with specified elevated temperature properties
EN 10028-3:2017, Flat products made of steels for pressure purposes — Part 3: Weldable fine grain steels,
normalized
EN 10028-4:2017, Flat products made of steels for pressure purposes — Part 4: Nickel alloy steels with
specified low temperature properties
EN 10028-7:2016, Flat products made of steels for pressure purposes — Part 7: Stainless steels
EN 10204:2004, Metallic products — Types of inspection documents
EN 10216-1:2013, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 1:
Non-alloy steel tubes with specified room temperature properties
EN 10216-2:2013+A1:2019, Seamless steel tubes for pressure purposes — Technical delivery conditions —
Part 2: Non-alloy and alloy steel tubes with specified elevated temperature properties
EN 10216-3:2013, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 3:
Alloy fine grain steel tubes
EN 10216-4:2013, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 4:
Non-alloy and alloy steel tubes with specified low temperature properties
EN 10216-5:2013, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 5:
Stainless steel tubes
EN 10217-1:2019, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 1:
Electric welded and submerged arc welded non-alloy steel tubes with specified room temperature properties
EN 10217-2:2019, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 2:
Electric welded non-alloy and alloy steel tubes with specified elevated temperature properties
EN 10217-3:2019, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 3:
Electric welded and submerged arc welded alloy fine grain steel tubes with specified room, elevated and low
temperature properties
EN 10217-4:2019, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 4:
Electric welded non-alloy steel tubes with specified low temperature properties
EN 10217-5:2019, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 5:
Submerged arc welded non-alloy and alloy steel tubes with specified elevated temperature properties
EN 10217-6:2019, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 6:
Submerged arc welded non-alloy steel tubes with specified low temperature properties
EN 10217-7:2014, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 7:
Stainless steel tubes
EN 10222-2:2017, Steel forgings for pressure purposes — Part 2: Ferritic and martensitic steels with
specified elevated temperatures properties
EN 10222-3:2017, Steel forgings for pressure purposes — Pa
...