CEN/TS 1591-3:2007

Flanges and their joints - Design rules for gasketed circular flange connections - Part 3: Calculation method for metal to metal contact type flanged joint

The aim of this Technical Specification is to describe a calculation method dedicated to Bolted Flange Connections (BFC) with metal to metal contact (MMC). It is dedicated to BFC where MMC occurs in a region between the outside diameter of the gasket and the inside diameter of the bolt hole region. For MMC inside the gasket and for MMC outside the bolt hole region, the present method is not appropriate.
The calculation method proposed in this Technical Specification is mainly based on the method described in EN 1591-1, dedicated to floating type BFC. The behaviour of the complete flanges-bolts-gasket system is considered. In assembly condition as well as for all the subsequent load conditions, the BFC components are maintained together by internal forces. This leads to deformations and forces balances (see Annex F) which gives the basic relations between the forces variations in the BFC.
The calculation of BFC with MMC leads to the consideration of an additional force compared to the EN 1591-1 calculation method: the reaction force in the MMC area. It explains why two compliance equations are required in this Technical Specification (in the EN 1591-1 calculation method just one compliance equation is needed to determine the internal forces in all the load conditions).
Unlike EN 1591-1 where the internal forces variations are determined with the compliance relation between the assembly and the considered load condition, here, the internal forces variations are determined by using the compliance relations between two consecutive load conditions.
This method does not treat non-gasketed pipe joints.
1.1   Requirement for use of the Method
Where permitted, the Method is an alternative to design validation by other means e.g.
-   special testing;
-   proven practice.
-   Use of standard flanges within permitted conditions
1.2   Geometry
The Method is applicable to the configurations having:
-   flanges whose section is given or may be assimilated to those given in Figures

Flansche und ihre Verbindungen - Regeln für die Auslegung von Flanschverbindungen mit runden Flanschen und Dichtung - Teil 3: Berechnungsmethode für Flanschverbindungen mit Dichtungen im Kraft-Nebenschluss

Brides et leurs assemblages - Règles de calcul des assemblages à brides circulaires avec joint - Partie 3 : Méthode de calcul pour les assemblages à brides de type contact métal-métal

La méthode constitue l'une des alternatives possibles (quand cela est permis), pour la justification de la conception d'un assemblage, au même titre que d'autres, par exemple :
-   des essais spécifiques ;
-   la référence à une expérience pratique justifiée.
1.1   Géométrie
La méthode de calcul est applicable aux configurations présentant :
-   des brides dont la section correspond ou peut être assimilée à l'une de celles présentées sur les Figures 4 à 12 de l'EN 1591-1 ;
-   quatre boulons identiques ou plus, répartis régulièrement ;
-   joint conçu pour des applications avec contact métal métal ;
-   des dimensions de brides qui satisfont aux conditions suivantes :
a)     ;
b)     ;
c)    .
NOTE 1   Voir l'Article 3 pour la signification des symboles.
NOTE 2   La condition  n'a pas besoin d'être satisfaite pour le collet d'une bride tournante.
NOTE 3   La condition   a pour objet de limiter l'inégalité de la répartition de la compression du joint qui peut résulter de l'espacement des boulons. Les valeurs 0,01 et 0,10 sont à utiliser respectivement pour les joints à faible dureté (non métalliques) et pour les joints durs (métalliques). Un critère plus précis est donné en Annexe A de l'EN 1591-1.
NOTE 4   Il peut être nécessaire de prêter attention à la manière dont les tolérances et la corrosion peuvent modifier les dimensions ; en la matière, il y a lieu de se référer au code ou à la réglementation selon lequel (laquelle) le calcul est effectué, par exemple, ces valeurs sont spécifiées dans l'EN 13445 et l'EN 13480.
Les configurations suivantes sont hors du domaine d'application de la méthode de calcul :
brides présentant une géométrie globalement non axisymétrique, par exemple : brides à segments démontables, brides à goussets raidisseurs.

Prirobnice in prirobnični spoji - Pravila za načrtovanje okroglih prirobničnih spojev s tesnili - 3. del: Način izračuna za prirobnice s kovinskim stikom

General Information

• Status: Published
• Publication Date: 24-Jul-2007
• ICS: 23.040.60 - Flanges, couplings and joints
• Technical Committee: CEN/TC 74 - Flanges and their joints
• Drafting Committee: CEN/TC 74/WG 10 - Calculation methods
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 04-Dec-2009
• Completion Date: 04-Dec-2009
• Directive: 97/23/EC - Directive 97/23/EC of the European Parliament and of the Council of 29 May 1997 on the approximation of the laws of the Member States concerning pressure equipment
• Mandate: M/071 - Mandate to CEN for standardization in the field of Pressure equipment
• Ref Project: SIST EN 1591-3:2009 - Flanges and their joints - Design rules for gasketed circular flange connections - Part 3: Calculation method for metal to metal contact type flanged joint

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.RPFlansche und ihre Verbindungen - Regeln für die Auslegung von Flanschverbindungen mit runden Flanschen und Dichtung - Teil 3: Berechnungsmethode für Flanschverbindungen mit Dichtungen im Kraft-NebenschlussBrides et leurs assemblages - Regles de calcul des assemblages a brides circulaires avec joint - Partie 3 : Méthode de calcul pour les assemblages a brides de type contact métal-métalFlanges and their joints - Design rules for gasketed circular flange connections - Part 3: Calculation method for metal to metal contact type flanged joint23.040.60Prirobnice, oglavki in spojni elementiFlanges, couplings and jointsICS:Ta slovenski standard je istoveten z:CEN/TS 1591-3:2007SIST EN 1591-3:2009en,fr,de01-april-2009SIST EN 1591-3:2009SLOVENSKI
STANDARD
TECHNICAL SPECIFICATIONSPÉCIFICATION TECHNIQUETECHNISCHE SPEZIFIKATIONCEN/TS 1591-3July 2007ICS 23.040.60 English VersionFlanges and their joints - Design rules for gasketed circularflange connections - Part 3: Calculation method for metal tometal contact type flanged jointBrides et leurs assemblages - Règles de calcul desassemblages à brides circulaires avec joint - Partie 3 :Méthode de calcul pour les assemblages à brides de typecontact métal-métalFlansche und ihre Verbindungen - Regeln für dieAuslegung von Flanschverbindungen mit runden Flanschenund Dichtung - Teil 3: Berechnungsmethode fürFlanschverbindungen mit Dichtungen im Kraft-NebenschlussThis Technical Specification (CEN/TS) was approved by CEN on 16 June 2007 for provisional application.The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit theircomments, particularly on the question whether the CEN/TS can be converted into a European Standard.CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS availablepromptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)until the final decision about the possible conversion of the CEN/TS into an EN is reached.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. CEN/TS 1591-3:2007: ESIST EN 1591-3:2009

Example of Gasket compression curve.44 Annex B (informative)
Local compression deformation.48 Annex C (informative)
Relaxation of the gasket: Three-parameter solid model.50 Annex D (informative)
Scatter of bolting-up methods.54 Annex E (informative)
Calculation sequences.55 Annex F (informative)
Determination of the compliance equations.59 Bibliography.60
“Flanges and their joints”, the secretariat of which is held by DIN. EN 1591 "Flanges and their joints — Design rules for gasketed flange connections" consists of the following three parts:  Part 1: Calculation method  Part 2: Gasket parameters  Part 3: Calculation method for metal to metal contact type flanged joint (CEN/TS)  Part 4: Qualification of personnel competency in the assembly of bolted joints fitted to equipment sub-ject to the Pressure Equipment Directive
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Cyprus, Czech Re-public, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithua-nia, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Swe-den, Switzerland and the United Kingdom. SIST EN 1591-3:2009

possibly different from the first c exponent marking deformation terms due to creep relaxation i Exponent marking terms related to the first compliance equation ii Exponent marking terms related to the second compliance equation 3.3 Symbols Where units are applicable, they are shown in brackets. Where units are not applicable, no indication is given. AB Effective total cross-section area of all bolts [mm2], Equation (36) AF, AL Gross radial cross-section area (including bolt holes) of flange ring, loose flange [mm2], Equations (5), (7), (8) AGe, AGt Gasket area, effective, theoretical [mm2], Equations (41), (39) C Coefficient to account for twisting moment in bolt load ratio, Equation (121) E0 Unloading Compressive modulus of elasticity of the gasket [MPa] at zero compressive stress Q = 0 [MPa] (see prEN 1591-2) EB, EF, EG, EL EM, EW Modulus of elasticity of the part designated by the subscript, at the temperature of the part [MPa] (for EG see prEN 1591-2) FA Additional external axial force [N], tensile force > 0, compressive force < 0, see Figure 1 of EN 1591-1:2001 FB Bolt force (sum of all bolts) [N] FBMMC Bolt force (sum of bolts) required to reach MMC [N] FG Gasket force [N] FGMMC Gasket force required to reach the MMC [N] FM Metal to metal contact force [N] FQ Axial fluid-pressure force [N], Equation (74) FR Force resulting from FA and MA [N], Equation (75) FRMMC Force resulting from FA and MA corresponding to the tightening force FBMMC [N] G(t) Relaxation function Equation (C.13) SIST EN 1591-3:2009

for assembly condition I = 0, for subsequent conditions I = 1, 2, 3, . IB Plastic torsion modulus [mm3] of bolt shanks, Equation (121) K1 Rate of change of compressive modulus of elasticity of the gasket with compressive stress, prEN 1591-2 Ks Systematic error due to the inaccuracy of the bolt tightening method MA Additional external moment [N · mm], Figure 1 of EN 1591-1:2001 Mt Bolt assembly torque [N · mm], Annex D of EN 1591-1:2001 Mt, B twisting moment [N · mm] applied to bolt shanks as a result of application of the bolt as-sembly torque Mt, Equations (121) and (D.8) to (D.11) of EN 1591-1:2001 P Pressure of the fluid [MPa], internal pressure > 0, external pressure < 0 (1 bar = 0,1 MPa) Q Mean effective gasket compressive stress [MPa], Q = FG/AGe QGMMCinf Inferior boundary of the range of gasket compressive stress in which the MMC appears [MPa] QGMMCsup Superior boundary of the range of gasket compressive stress in which the MMC appears [MPa] QI Mean effective required gasket compressive stress at load condition I [MPa] Qmin Minimum necessary compressive stress in gasket for assembly condition (on the effective gasket area) [MPa], Equation (93), (see prEN 1591-2) Qmax Maximum allowable compressive stress in the gasket (depends on the gasket materials, construction, dimensions and the roughness of the flange facings) [MPa], Equation (120), see prEN 1591-2 (including safety margins, which are same for all load conditions) Qmax, Y Yield stress characteristic of the gasket materials and construction, see Table 1, and prEN 1591-2 [MPa] TB, TF, TG, TL, TM, TW
Temperature (average) of the part designated by the subscript [°C] or [K], Equation (77), (78) and (80), (81) TO Temperature of connection at assembly [°C] or [K] (usually + 20 °C) U Axial displacement [mm]; ∆U according to Equations (76), (77), (78) and Equations (79), (80) and (81). WF, WL, WX Resistance of the part and/or cross-section designated by the subscript [N · mm], Equa-tions (123), (135), (137), (139) XB, XG, XM, XW Axial flexibility modulus of bolts, gasket, metallic compression limiter ring, washer [1/mm], Equations (37), (44), (52), (46) XFB Axial flexibility modulus corresponding to local compression of flange at contact area with nut [1/mm], Equation (73) SIST EN 1591-3:2009

Load ratio of flange ring due to radial force, Equation (131) ΨZ Particular value of Ψ, Equation (123), Table 2 ΦB, ΦF, ΦG, ΦL, ΦX Load ratio of part and/or cross-section designated by the subscript, to be calculated for all
load conditions, Equation (120), (121), (122), (134), (136), (138) Φmax Reduced maximum allowable load ratio, Equation (108) αB, αF, αG, αL, αW, αM Thermal expansion coefficient of the part designated by the subscript, averaged between
T0 and TB, TF, TG, TL, TW, TM
[K– 1], Equation (77), (78) and (80), (81) β, γ, δ, θ
Intermediate variables, Equations (9), (20), (21), (22), (43), (108), (124) κ, λ, χ
Annex D ε+, ε– Scatter for the global load of all the bolts above nominal value, below nominal value,
Equations (109), to (111) η Tangent of the propagation angle of the local compression (see Annex B) π Numerical constant (π = 3,141593) σ Stress [MPa] (Annex C) τR Relaxation time [s] (Annex C) φG Angle of inclination of a sealing face [rad or deg], Figure 3 of EN 1591-1:2001, Table 2 φS Angle of inclination of connected shell wall [rad or deg], Figures 6, 7 of EN 1591-1:2001 ξ0µ ξ1µ ω0µ ω1
Material parameters regarding the stress relaxation function of the gasket (see Annex C). 3.4 Terminology 3.4.1 Flanges Integral flange: Flange attached to the shell either by welding (e.g. neck weld, see Figures 4 to 7 of EN 1591-1:2001 or slip on weld see Figures 8 and 11 of EN 1591-1:2001) or cast onto the envelope (integrally cast flanges, Type 21) Blank flange: Flat closure, Figure 9 of EN 1591-1:2001 Loose flange: Separate flange ring abutting a collar, Figure 10 of EN 1591-1:2001 Hub: Axial extension of flange ring, usually connecting flange ring to shell, Figures 4, 5 of EN 1591-1:2001 Collar: Abutment for a loose flange, Figure 10 of EN 1591-1:2001 3.4.2 Loading External loads: Forces and/or moments applied to the connection by attached equipment, e.g. weight and thermal expansion of pipes. 3.4.3 Loading conditions Load condition: State with set of applied simultaneous loads; designated by I. Assembly condition: Load condition due to initial tightening of bolts (bolting up), designated by I = 0 Subsequent condition: Load condition subsequent to assembly condition, e.g. operating condition, test condition, conditions arising during start-up and shut-down; designated by I = 1,
2, 3 . 3.4.4 Compliances Compliance: Inverse stiffness (axial), symbol Y, [mm/N] SIST EN 1591-3:2009

axial:
symbol X, [1/mm]
rotational: symbol Z, [1/mm3]
Figure 1 — 2 types of MMC BFC: gasket with limiter ring and gasket inserted in a groove, with theoretical dimensions 4 Calculation parameters 4.1 General The parameters defined in this Clause are effective dimensions and areas as well as stiffness parameters. Most Parameters of 4.2 to 4.4 are extracted from EN 1591-1:2001. 4.2 Flange parameters 4.2.1 General The formulae given in 4.2 shall be used for each of the two flanges and where applicable, the two collars of a connection. Specific flange types are treated as follows: Integral flange: calculated as an equivalent ring with rectangular cross-section, dimensions bF · eF con-nected at diameter dE to an equivalent shell of constant wall thickness eE. Blank flange: calculated as an equivalent ring with rectangular cross-section, dimensions bF · eF, con-nected at diameter dE = d0 to a plate of constant thickness e0. It may have a central opening of diameter d9. If a nozzle is connected at the opening the nozzle is not taken into account in the calculation. Loose flange: calculated as an equivalent ring with rectangular cross-section dimensions bL · eL without connection to a shell. SIST EN 1591-3:2009

It follows that hG, hH and hL can vary with each iteration necessary to calculate bGe and dGe (see 4.3.2).  for the calculation of load ratios (Clause 6), the most favourable value between d7 min and d7 max can be used. 4.2.5 Flexibility-related flange parameters NOTE When the gasket is of the flat type, the parameter hQ below can be calculated only when dGe has been deter-mined, i.e. when the calculations stated in 4.3.2 have been carried out. 4.2.5.1 Integral flange and collar <>SEFFE/ϕγcos⋅⋅⋅=dbde (20) FEES/,eed⋅⋅=ϕθcos550 (21) FQFP//eeee=−=1λ (22) NOTE eP and eQ are defined in Figures 4 to 12 of EN 1591-1:2001 (when eP = eF, eQ = 0). <><><>[]{}422236216331411θγθθλλλθγθγ⋅→⋅→⋅−⋅→→−⋅⋅⋅→⋅→=/Fc (23) <><>θγθλ⋅→→⋅−⋅⋅=12111//,EEeFSdeh (24) <><>θγθγλ⋅→⋅−−=1212/FTeh (25) SIST EN 1591-3:2009

<>2ymax,⋅⋅π→⋅→⋅⋅⋅π=QdFEZhEZhEdebGeGFFGFFGGmGeGGi~/~~// GeGGm/,AFKEE⋅→=1050 FF~,ZZ according to Equation (30) or (34) In all cases: GeGGebdd−=2 2 Metal gaskets with curved surfaces, simple contact, see Figures 3b, 3c of EN 1591 First approximation:
GGtGrGi/EQbbymax,2cos6⋅⋅⋅=ϕ More accurate:
2ymax,2cos6⋅⋅π→⋅⋅π⋅⋅=QdFEdFbGeGGGeGGrGiϕ In all cases: G0Gedd=
3 Metal octagonal section gaskets see Figure 3d of EN 1591 In all cases:
bGi = length bGe according to Figure 3d of EN 1591 (Projection of contacting surfaces in axial direction.) GtGedd= 4 Metal oval or circular section gaskets, double contact see Figures 3e, 3f of EN 1591 First approximation:
GGtGrGi/EQbbymax,2cos12⋅⋅⋅=ϕ More accurate:
2ymax,2cos12⋅⋅π→⋅⋅π⋅⋅=QdFEdFbGeGGGeGGrGiϕ In all cases: GtGedd=
)(WWBWW21224ddneX−⋅π⋅⋅= (46) For other kind of washers the axial flexibility modulus has to be determined following the manufacturer indi-cations. 4.6 Calculation parameters for the metal to metal contact area 4.6.1 Metal to metal contact theoretical dimensions Theoretical diameter of the metal to metal contact : dMt 221MMMtddd→= (47) Theoretical width of the metal to metal contact : bMt 212MMMtddb→= (48) (see Figure 1) 4.6.2 Metal to metal contact effective dimensions 4.6.2.1 Inside diameter of the metal to metal contact area The inside diameter of the metal to metal contact area depends on the flanges geometries and on the rotation angles of the flanges: In the case of MMC with compression limiter ring:
FFMFGFGGGeeM~~ΘΘ∆∆→−−−×→=eeeedd21 (49) SIST EN 1591-3:2009

Figure 2 — Inside diameter of the MMC area 4.6.2.2 Effective diameter of the metal to metal contact area The effective metal to metal contact diameter dMe is the diameter where the metal to metal contact force acts. eMMeMeMMMMe122112222423ddddddd→→⋅→= (51) SIST EN 1591-3:2009

We consider the gasket thickness in compression as a function of the gasket compression stress is linear by pieces (see Annex A). Such as forGjGGjQQQ≤≤−1, the thickness of the gasket in compression for a gasket compression stress QG is given by: <><>)()(GjGjGjGjGjGGjGG1111−−−−−−⋅−→=QQeeQQeQe (53) 4.8 Local deformation parameters 4.8.1 General Local compressions may occur at the contact areas between the different components of the connection. When significant, these local compressions have to be considered in the axial deformation balances. Here below are given the expressions of local compressions at the different contact area in the connection. (See also Annex B). SIST EN 1591-3:2009
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