oSIST prEN 1591-1:2021
(Main)Flanges and their joints - Design rules for gasketed circular flange connections - Part 1: Calculation
Flanges and their joints - Design rules for gasketed circular flange connections - Part 1: Calculation
This document defines a calculation method for bolted, gasketed, circular flange joints. Its purpose is to ensure structural integrity and control of leak tightness. It uses gasket parameters based on definitions and test methods specified in EN 13555:2014.
The calculation method is not applicable to joints with a metallic contact out of the sealing face or to joints whose rigidity varies appreciably across gasket width. For gaskets in incompressible materials, which permit large deformations, the results given by the calculation method can be excessively conservative (i.e. required bolting load too high, allowable pressure of the fluid too low, required flange thickness too large, etc.).
Flansche und ihre Verbindungen - Regeln für die Auslegung von Flanschverbindungen mit runden Flanschen und Dichtung - Teil 1: Berechnung
Dieses Dokument legt eine Berechnungsmethode für Flanschverbindungen mit runden Flanschen, Schrauben und Dichtung fest. Es hat den Zweck, die Festigkeit der Konstruktion sicherzustellen und die Dichtigkeit zu kontrollieren. Dafür werden Dichtungskennwerte angewendet, die auf Definitionen und Prüfverfahren nach EN 13555:2014 beruhen.
Die Berechnungsmethode ist nicht anwendbar auf Flanschverbindungen mit einem metallischen Dichtflächenkontakt und auf Flanschverbindungen, deren Steifigkeit über die Dichtungsbreite stark schwankt. Bei Dichtungen in unelastischen Werkstoffen, die starke Verformungen zulassen, können die Ergebnisse nach dieser Berechnungsmethode übermäßig konservativ sein (d. h. erforderliche Schrauben-kraft zu hoch, zulässiger Mediendruck zu gering, erforderliche Flanschdicke zu groß usw.).
Brides et leurs assemblages - Règles de calcul des assemblages à brides circulaires avec joint - Partie 1: Méthode de calcul
Le présent document définit une méthode de calcul des assemblages à brides circulaires boulonnés avec joint. Son objectif est d'en assurer l'intégrité structurale et la maîtrise de l'étanchéité. Elle utilise des paramètres de joints basés sur les définitions et les modes opératoires d'essais spécifiés dans l'EN 13555:2014:2014.
La méthode de calcul ne s'applique pas aux assemblages à contact métallique en dehors de la face d'étanchéité ni aux assemblages dont la rigidité varie de façon notable sur la largeur du joint. En ce qui concerne les joints en matériau incompressible qui présentent des déformations importantes, les résultats fournis par la méthode de calcul peuvent être excessivement conservateurs (c'est-à-dire effort de boulonnage requis trop élevé, pression admissible de fluide trop faible, épaisseur de bride nécessaire trop importante, etc.).
Prirobnice in prirobnični spoji - Pravila za konstruiranje prirobničnih spojev, sestavljenih iz okroglih prirobnic in tesnil - 1. del: Izračun
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 1591-1:2021
01-maj-2021
Prirobnice in prirobnični spoji - Pravila za konstruiranje prirobničnih spojev,
sestavljenih iz okroglih prirobnic in tesnil - 1. del: Izračun
Flanges and their joints - Design rules for gasketed circular flange connections - Part 1:
Calculation
Flansche und ihre Verbindungen - Regeln für die Auslegung von Flanschverbindungen
mit runden Flanschen und Dichtung - Teil 1: Berechnung
Brides et leurs assemblages - Règles de calcul des assemblages à brides circulaires
avec joint - Partie 1: Méthode de calcul
Ta slovenski standard je istoveten z: prEN 1591-1
ICS:
23.040.60 Prirobnice, oglavki in spojni Flanges, couplings and joints
elementi
oSIST prEN 1591-1:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 1591-1:2021
DRAFT
EUROPEAN STANDARD
prEN 1591-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2021
ICS 23.040.60 Will supersede EN 1591-1:2013
English Version
Flanges and their joints - Design rules for gasketed circular
flange connections - Part 1: Calculation
Brides et leurs assemblages - Règles de calcul des Flansche und ihre Verbindungen - Regeln für die
assemblages à brides circulaires avec joint - Partie 1: Auslegung von Flanschverbindungen mit runden
Méthode de calcul Flanschen und Dichtung - Teil 1: Berechnung
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 74.
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,
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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1591-1:2021 E
worldwide for CEN national Members.
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Contents Page
European foreword . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions, subscripts, special marks and symbols . 7
3.1 Terms and definitions . 7
3.2 Subscripts and special marks . 16
3.2.1 Subscripts . 16
3.2.2 Special marks . 17
3.3 Symbols . 17
4 Requirements for use of the calculation method . 23
4.1 General . 23
4.2 Geometry . 23
4.3 Material . 24
4.4 Loads . 24
5 Calculation parameters . 24
5.1 General . 24
5.2 Flange parameters . 25
5.2.1 General . 25
5.2.2 Flange ring . 25
5.2.3 Connected shell . 26
5.2.4 Flexibility-related flange parameters . 27
5.3 Bolt and washer parameters . 28
5.3.1 General . 28
5.3.2 Effective cross-section area of bolts . 28
5.3.3 Flexibility modulus of bolts . 29
5.3.4 Geometric parameters for washers and contact surfaces . 29
5.3.5 Flexibility modulus of washers . 29
5.4 Gasket parameters . 29
5.4.1 General . 29
5.4.2 Theoretical dimensions . 29
5.4.3 Effective dimensions . 30
5.4.4 Axial flexibility modulus of gasket . 31
5.4.5 Lever arms . 33
6 Forces . 34
6.1 General . 34
6.2 Applied loads . 34
6.2.1 Assembly condition (I = 0) . 34
6.2.2 Subsequent conditions (I = 1, 2 …) . 34
6.3 Compliance of the joint . 35
6.4 Minimum forces necessary for the gasket. 36
6.4.1 Assembly condition (I = 0) . 36
6.4.2 Subsequent conditions (I = 1, 2, ….) . 36
6.5 Internal forces in assembly condition (I = 0) . 37
6.5.1 Required forces . 37
6.5.2 Accounting for bolt-load scatter at assembly . 38
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6.6 Internal forces in subsequent conditions (I = 1, 2, …) . 39
7 Load limits . 39
7.1 General . 39
7.2 Bolts . 40
7.3 Gasket . 41
7.4 Integral flange and collar . 41
7.5 Blank flange . 43
7.6 Collar with loose flange . 43
(informative) Dimensions of standard metric bolts . 45
(informative) Tightening . 46
B.1 Scatter of initial bolt load of a single bolt — Indicative values ε and ε for a single bolt 46
1- 1+
B.2 Scatter for the global load of all the bolts . 46
B.3 Manual uncontrolled tightening . 47
B.4 Assembly using torque wrench . 47
B.5 Assembly using bolt tensioner . 48
(informative) Flange rotations . 50
C.1 General . 50
C.2 Use of flange rotation . 50
C.3 Calculation of flange rotations . 50
(informative) Use of the calculation method . 52
D.1 Calculation method principle . 52
D.2 Mechanical model . 53
D.3 Required checks . 54
D.4 Calculation sequence . 54
(informative) Gasket/flange face friction coefficients examples . 57
(informative) Checking a specified assembly bolt force . 58
(informative) Sealing gasket parameter when no leakage rate is specified . 59
(informative) Alternative calculation procedure taking into account the plastic
deformation of the gasket in subsequent load conditions procedures (after assembly) . 60
H.1 Introduction . 60
H.2 Calculation procedure. 60
H.2.1 General description . 60
H.2.2 No additional plastic deformation . 61
H.2.3 Additional plastic deformation. 61
H.3 Flat gaskets . 61
H.3.1 Flat gaskets with small or median deformations . 61
H.3.2 Flat gaskets with greater deformations . 63
H.4 Metal gaskets with curved surfaces (Figures 4b, c, e, f ) . 64
H.5 Metal gaskets with octagonal section (Figure 4d) . 64
(informative) Available, incomplete models for conversion of the leakage rates in
different conditions (based on certain flow models) . 65
I.1 Introduction and warning . 65
I.2 Flow theory fundamentals . 65
I.2.1 Transport modes . 65
I.2.2 Case of gases . 66
I.2.3 Case of liquids: Parallel capillary model . 67
I.3 Factors of influence on the leakage rate of gaskets and gasketed joints . 67
I.3.1 List of identified factors . 67
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I.3.2 Limits and restriction of the proposed models . 67
I.3.3 Dependence on pressure . 68
I.3.4 Dependence on temperature . 69
I.3.5 Dependence on the type of fluid . 70
I.3.6 Influence of the gasket thickness . 70
I.3.7 Influence of gasket width . 71
I.3.8 Influence of gasket stress . 71
I.3.9 Influence of other factors . 72
I.3.10 Conclusion on the factors of influence . 72
I.4 Practical application for EN 1591-1 calculations . 72
I.4.1 General . 72
I.4.2 Determination of a trend for the leakage rate for the flange connection in “actual” from
“reference” conditions. 74
I.4.3 Determination of a trend for the leakage rate for the flange connection in “reference”
from “actual” conditions . 75
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2014/68/EU Pressure Equipment Directive aimed to be
covered. 77
Bibliography . 79
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European foreword
This document (prEN 1591-1:2021) has been prepared by Technical Committee CEN/TC 74 “Flanges and
their joints”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 1591-1:2013.
The major changes in comparison with the previous edition include:
— Removal of the possibility to handle gasket creep/relaxation behaviour through additional
deflection. In this new revision, the gasket creep/relaxation behaviour is only treated using the P
QR
factor;
— Correction of the lever arms considered for integral flange and collar load ratio calculation (127),
(135);
— Introduction of a reduced maximum allowable value of load ratio for large integral flange and collar
(128) (149);
— Possibility to check a bolted flange connection for a specified assembly bolt force value, previously
treated in the body of the document is now defined in a new informative annex (Annex F);
— Update of the Flange/gasket friction factors in Annex E;
— Update of the Annex ZA in accordance with the Directive 2014/68/EU on Pressure Equipment.
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(s).
For relationship with EU Directive 2014/68/EU, see informative Annex ZA, which is an integral part of
this document.
EN 1591 consists of several parts:
— EN 1591-1, Flanges and their joints — Design rules for gasketed circular flange connections — Part 1:
Calculation;
— CEN/TR 1591-2, Flanges and their joints — Design rules for gasketed circular flange connections —
Part 2: Gasket parameters;
— CEN/TS 1591-3, Flanges and their joints — Design rules for gasketed circular flange connections —
Part 3: Calculation method for metal to metal contact type flanged joint;
— EN 1591-4, Flanges and their joints — Part 4: Qualification of personnel competency in the assembly of
the bolted connections of critical service pressurized systems;
— CEN/TR 1591-5, Flanges and their joints — Design rules for gasketed circular flange connections —
Part 5: Calculation method for full face gasketed joints.
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The calculation method satisfies both leak tightness and strength criteria. The behaviour of the complete
flanges-bolts-gasket system is considered. Parameters taken into account include not only basic ones
such as:
— fluid pressure;
— material strength values of flanges, bolts and gaskets;
— gasket compression factors;
— nominal bolt load;
but also:
— possible scatter due to bolting up procedure;
— changes in gasket force due to deformation of all components of the joint;
— influence of connected shell or pipe;
— effect of external axial and lateral forces and torsion and bending moments;
— effect of temperature difference between bolts and flange ring.
The use of this calculation method is particularly useful for joints where the bolt load is monitored when
bolting up. The greater the precision of this, the more benefit can be gained from application of the
calculation method.
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1 Scope
This document defines a calculation method for bolted, gasketed, circular flange joints. Its purpose is to
ensure structural integrity and control of leak tightness. It uses gasket parameters based on definitions
and test methods specified in EN 13555:2014.
The calculation method is not applicable to joints with a metallic contact out of the sealing face or to joints
whose rigidity varies appreciably across gasket width. For gaskets in incompressible materials, which
permit large deformations, the results given by the calculation method can be excessively conservative
(i.e. required bolting load too high, allowable pressure of the fluid too low, required flange thickness too
large, etc.).
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.
1)
EN 13555:2014 , Flanges and their joints — Gasket parameters and test procedures relevant to the design
rules for gasketed circular flange connections
3 Terms and definitions, subscripts, special marks and symbols
For the purposes of this document, the following terms and definitions, subscripts, special marks and
symbols apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1 Terms and definitions
NOTE Figure 1 to Figure 14 illustrate the notation corresponding to the geometric parameters. They only show
principles and are not intended to be practical designs. They do not illustrate all possible flange types for which the
calculation method is valid.
For standard flange types, e.g as shown in EN 1092 or EN 1759, the relevant figures are the following:
Type 01 Figure 10
Type 02 Figure 12
Type 04 Figure 12
Type 05 Figure 11
Type 07 Figure 12
Type 11 Figure 6
1) Under revision.
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Type 12 Figure 13
Type 13 Figure 14
Type 21 Figures 6 to 9
3.1.1
flanges
3.1.1.1
integral flange
flange attached to the shell either by welding (e.g. neck weld, see Figure 6 to Figure 9, or slip on weld, see
Figure 10 and Figure 13) or cast onto the envelope (integrally cast flanges, type 21)
3.1.1.2
blank or blind flange
flat closure (see Figure 11)
3.1.1.3
loose flange
separate flange ring abutting a collar (see Figure 12)
3.1.1.4
hub
axial extension of flange ring, usually connecting flange ring to shell (see Figure 6 and Figure 7)
3.1.1.5
collar or stub
abutment for a loose flange (see Figure 12)
3.1.2
loading
3.1.2.1
external loads
forces and/or moments applied to the joint by attached equipment, e.g. weight and thermal expansion of
pipes
3.1.3
load conditions
3.1.3.1
load condition
state with set of applied simultaneous loads; designated by I
3.1.3.2
assembly condition
load condition due to initial tightening of bolts (bolting up), designated by I = 0
3.1.3.3
subsequent condition
load condition subsequent to assembly condition, e.g. test condition, operating condition, conditions
arising during start-up and shut-down; designated by I = 1, 2, 3 .
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3.1.4
compliances
3.1.4.1
compliance
inverse stiffness (axial), symbol Y, [mm/N]
3.1.4.2
flexibility modulus:
inverse stiffness modulus, excluding elastic constants of material:
— axial: symbol X, [1/mm]
3
— rotational: symbol Z, [1/mm ]
Figure 1 — Loads and lever arms
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Figure 2 — Washer or spacer
𝑙𝑙 =𝑙𝑙 −𝑙𝑙
𝑒𝑒 𝐵𝐵 𝑠𝑠
Figure 3 — Bolts
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Figure 4 — Gaskets
Key
1 male flange (tongue)
2 female flange (groove)
3 gasket
Figure 5 — Details for tongue and groove facing
11
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Key
1 shell
2 hub
3 ring
Figure 6 — Weld-neck flanges with cylindrical shells (example 1)
Key
1 shell
2 hub
3 ring
Figure 7 — Weld-neck flanges with cylindrical shells (example 2)
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Key
1 shell
2 ring
Figure 8 — Flanges welded to conical shells
Key
1 shell
2 ring
Figure 9 — Flanges welded to spherical shells
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Key
1 shell
2 ring
Figure 10 — Weld-on plate flange
Key
1 plate
2 ring
Figure 11 — Blank flange
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Key
1 shell
2 collar
3 loose flange
Figure 12 — Collar with loose flanges
Figure 13 — Hubbed slip-on welded flange
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Figure 14 — Hubbed threaded flange
3.2 Subscripts and special marks
3.2.1 Subscripts
A – Additional (F , M )
A A
B – Bolt
D – Equivalent cylinder (tapered hub + connected shell) for load limit calculation
E – Equivalent cylinder (tapered hub + connected shell) for flexibility calculation
F – Flange
G – Gasket
H – Hub
I – Load condition identifier (taking values 0, 1, 2 .)
L – Loose flange, Lateral (F )
LI
M – Moment
N – Nut
P – Fluid pressure
Q – Net axial force due to pressure
R – Net axial force due to external
...
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