SIST EN 1591-1:2014
(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 European Standard 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. 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 Flanschverbindungen - Regeln für die Auslegung von Flanschverbindungen mit runden Flanschen und Dichtung - Teil 1: Berechnung
1.1 Allgemeines
Diese Europäische Norm legt eine Berechnungsmethode für Flanschverbindungen mit runden Flanschen, Schrauben und Dichtung fest. Sie hat den Zweck, die Festigkeit der Konstruktion sicherzustellen und die Dichtigkeit zu kontrollieren. Die folgenden Gleichungen verwenden Dichtungskennwerte, die auf Definitionen und Prüfverfahren nach EN 13555 beruhen.
1.2 Anforderung an die Anwendung dieser Berechnungsmethode
Diese Berechnungsmethode bietet, sofern zulässig, eine Alternative zum Nachweis der Gültigkeit der Auslegung mit anderen Mitteln, z. B.:
- besondere Prüfung;
- bewährte Praxis;
- Verwendung genormter Flansche unter zulässigen Bedingungen.
1.3 Gültigkeit
1.3.1 Geometrie
Die Berechnungsmethode ist anwendbar bei Konfigurationen mit:
- Flanschen, deren Querschnitt angegeben oder auf die in Bild 4 bis Bild 12 dargestellten Flansche zurückzuführen ist;
- vier oder mehr gleichmäßig verteilten identischen Schrauben;
- Dichtung, deren Querschnitt und Einbaulage unter Belastung durch eine der Konstruktionen in Bild 3 dargestellt werden kann;
- Flanschmaßen, die folgende Bedingungen erfüllen:
a)
b)
ANMERKUNG 1 Zur Bedeutung der Formelzeichen siehe Abschnitt 3.
ANMERKUNG 2 Die Bedingung bF/eF 5,0 braucht bei Bunden oder Bördeln in Verbindung mit losen Flanschen nicht eingehalten zu werden.
ANMERKUNG 3 Wurden die Auswirkungen von Korrosion in der Auslegung berücksichtigt, sollten diese Zuschläge bei der Berechnung wieder abgezogen werden. Eventuell ist auch auf die Auswirkungen von Maßtoleranzen zu achten; andere Regelwerke, nach denen die Berechnung erfolgt ist, sollten berücksichtigt werden, zum Beispiel sind Werte in EN 13445 und EN 13480 angegeben.
Die folgenden Konfigurationen liegen außerhalb des Anwendungsbereichs dieser Berechnungsmethode:
- Flansche mit im Wesentlichen nicht axialsymmetrischer Geometrie, z. B. geteilte lose Flansche, mit Stegen verstärkte Flansche;
- Verbindungen, bei denen die Flansche direkten oder indirekten metallischen Kontakt zueinander innerhalb und/oder außerhalb der Dichtung, innerhalb und/oder außerhalb des Lochkreisdurchmessers haben.
1.3.2 Werkstoffe
Werte für Nenn Berechnungsspannungen sind in dieser Berechnungsmethode nicht festgelegt. Sie sind abhängig von anderen Regelwerken, die angewendet werden; diese Werte sind z. B. in EN 13445 und EN 13480 angegeben.
Nenn Berechnungsspannungen für Schrauben sind wie für Flansche und Schalen zu ermitteln. Die Dichtung wird dargestellt durch elastisches Verhalten mit einer Korrektur für den plastischen Anteil.
Bei Dichtungen in unelastischen Werkstoffen, die starke Verformungen zulassen (z. B. Flachdichtungen, die größtenteils aus Gummi bestehen), können die Ergebnisse nach dieser Berechnungsmethode übermäßig konservativ sein (d. h. erforderliche Schraubenkraft zu hoch, zulässiger Mediendruck zu gering, erforderliche Flanschdicke zu groß usw.), da die Methode diese Eigenschaften vernachlässigt.
1.3.3 Belastungen
Die Berechnungsmethode gilt für folgende Belastungsarten:
- Mediendruck: innen oder außen;
- äußere Belastungen: Axial und Querkräfte, Torsions und Biegemomente;
- axiale Ausdehnung von Flanschen, Schrauben und Dichtungen, vor allem infolge von Temperatur-einwirkungen.
In der Berechnung sind alle Betriebszustände (Anfahren, Prüfung, Betrieb, Reinigung, Instandhaltung, Abfahren und sonstige außergewöhnliche Zustände) zu berücksichtigen, soweit sie sich auf die Konstruktion auswirken.
1.3.4 Mechanisches Modell
Die Berechnungsmethode beruht auf dem folgenden mechanischen Modell:
a) die Geometrie der Flansche und der Dichtung ist axialsymmetrisch. Kleine Abweichungen, z. B. aufgrund einer begrenzten Anzahl von Schrauben, sind zulässig. Geteilte lose Flansche oder ovale Flansche sind unzulässig;
Brides et leurs assemblages - Règles de calcul des assemblages à brides circulaires avec joint - Partie 1: Méthode de calcul
1.1 Généralités
La présente Norme européenne 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. Les équations suivantes utilisent des paramètres de joints basés sur les définitions et les modes opératoires d'essais spécifiés dans l'EN 13555.
1.2 Prescription d'emploi
La méthode de calcul 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 ;
- l'utilisation de brides normalisées, dans les conditions autorisées.
1.3 Domaine de validité
1.3.1 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 dans les Figures 4 à 12 ;
- quatre boulons identiques ou plus, répartis régulièrement ;
- un joint dont la section et la configuration après chargement peuvent être assimilées à l'une de celles présentées en Figure 3 ;
- des dimensions de brides qui satisfont aux conditions suivantes :
a) 0,2 ≤ bF/eF ≤ 5,0 ; 0,2 ≤ bL/eL ≤ 5,0
b)
NOTE 1 Voir l'Article 3 pour la signification des symboles.
NOTE 2 La condition bF/eF ≤ 5,0 n'a pas besoin d'être satisfaite pour le collet d'une bride tournante.
NOTE 3 Lorsqu'une surépaisseur de corrosion a été appliquée dans la conception, il convient de la soustraire lors du calcul. Il peut être nécessaire de prêter attention à la manière dont les tolérances peuvent modifier les dimensions ; en la matière, il convient 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 ;
- assemblages à brides à contact métal-métal direct ou indirect entre brides, à l'intérieur et/ou à l'extérieur du joint, à l'intérieur et/ou à l'extérieur du cercle de boulonnage.
1.3.2 Matériaux
La méthode de calcul ne spécifie pas de valeurs des contraintes nominales de calcul. Elles dépendent des autres codes qui sont appliqués, par exemple, ces valeurs sont spécifiées dans l'EN 13445 et l'EN 13480.
Les contraintes nominales de calcul des boulons sont à déterminer selon les mêmes règles que pour les brides et les enveloppes d'appareils. Le joint est modélisé par un comportement élastique avec correction plastique.
Pour les joints en matériau incompressible qui présentent de grandes déformations (par exemple : les joints plats dont le caoutchouc est le composant majeur), les résultats fournis par la méthode 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.), car elle ne prend pas en compte l'effet de telles propriétés.
1.3.3 Sollicitations
La méthode de calcul est applicable pour les sollicitations suivantes :
- pression du fluide : interne ou externe ;
- charges extérieures : forces axiales et latérales ainsi que moments de torsion et de flexion ;
- dilatation axiale des brides, boulons et joint, particulièrement due aux changements de température.
Toutes les situations (démarrage, épreuve, service, nettoyage, maintenance, arrêt et autres situations exceptionnelles) doivent être prises en compte dans le calcul dans la mesure où elles ont une influence sur la conception.
1.3.4 Modèle mécanique
La méthode de calcul est basée sur le modèle mécanique suivant :
Prirobnice in prirobnični spoji - Pravila za konstruiranje prirobničnih spojev, sestavljenih iz okroglih prirobnic in tesnil - 1. del: Izračun
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Flansche und Flanschverbindungen - Regeln für die Auslegung von Flanschverbindungen mit runden Flanschen und Dichtung - Teil 1: BerechnungBrides et leurs assemblages - Règles de calcul des assemblages à brides circulaires avec joint - Partie 1: Méthode de calculFlanges and their joints - Design rules for gasketed circular flange connections - Part 1: Calculation23.040.60Prirobnice, oglavki in spojni elementiFlanges, couplings and jointsICS:Ta slovenski standard je istoveten z:EN 1591-1:2013SIST EN 1591-1:2014en,fr,de01-februar-2014SIST EN 1591-1:2014SLOVENSKI
STANDARDSIST EN 1591-1:2002+A1:2009/AC:2011SIST EN 1591-1:2002+A1:20091DGRPHãþD
SIST EN 1591-1:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 1591-1
December 2013 ICS 23.040.60 Supersedes EN 1591-1:2001+A1:2009English Version
Flanges and their joints - Design rules for gasketed circular flange connections - Part 1: Calculation
Brides et leurs assemblages - Règles de calcul des assemblages à brides circulaires avec joint - Partie 1: Méthode de calcul
Flansche und ihre Verbindungen - Regeln für die Auslegung von Flanschverbindungen mit runden Flanschen - Teil 1: Berechnung This European Standard was approved by CEN on 12 October 2013.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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:
Avenue Marnix 17,
B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1591-1:2013 ESIST EN 1591-1:2014
EN 1591-1:2013 (E) 2 Contents Page Foreword .5 1 Scope .7 2 Normative references .7 3 Notation .7 3.1 Use of figures .7 3.2 Subscripts and special marks .7 3.2.1 Subscripts .7 3.2.2 Special marks .9 3.3 Symbols .9 3.4 Terminology . 14 3.4.1 Flanges . 14 3.4.2 Loading . 14 3.4.3 Load conditions . 14 3.4.4 Compliances . 14 4 Requirements for use of the calculation method . 22 4.1 General . 22 4.2 Geometry . 22 4.3 Material . 23 4.4 Loads . 23 5 Checking the assembly for a specified initial tightening bolt force (or torque) . 23 6 Calculation parameters . 24 6.1 General . 24 6.2 Flange parameters . 24 6.2.1 General . 24 6.2.2 Flange ring . 25 6.2.3 Connected shell . 26 6.2.4 Flexibility-related flange parameters . 27 6.3 Bolt and washer parameters . 28 6.3.1 General . 28 6.3.2 Effective cross-section area of bolts . 28 6.3.3 Flexibility modulus of bolts . 28 6.3.4 Geometric parameters for washers and contact surfaces . 28 6.3.5 Flexibility modulus of washers . 29 6.4 Gasket parameters . 29 6.4.1 General . 29 6.4.2 Theoretical dimensions . 29 6.4.3 Effective dimensions . 29 6.4.4 Axial flexibility modulus of gasket . 30 6.4.5 Lever arms . 32 7 Forces . 33 7.1 General . 33 7.2 Applied loads . 33 7.2.1 Assembly condition (I = 0) . 33 7.2.2 Subsequent conditions (I = 1, 2 …) . 33 7.3 Compliance of the joint . 34 7.4 Minimum forces necessary for the gasket . 35 7.4.1 Assembly condition (I = 0) . 35 7.4.2 Subsequent conditions (I = 1, 2, ….) . 35 7.5 Internal forces in assembly condition (I = 0). 35 7.5.1 Required forces . 35 SIST EN 1591-1:2014
EN 1591-1:2013 (E) 3 7.5.2 Accounting for bolt-load scatter at assembly . 36 7.6 Internal forces in subsequent conditions (I = 1, 2, …) . 37 8 Load limits . 38 8.1 General . 38 8.2 Bolts . 38 8.3 Gasket . 39 8.4 Integral flange and collar . 39 8.5 Blank flange . 41 8.6 Loose flange with collar. 42 Annex A (informative)
Dimensions of standard metric bolts . 43 Annex B (informative)
Tightening . 44 B.1 Scatter of initial bolt load of a single bolt — Indicative values 01- and 01+ for a single bolt . 44 B.2 Scatter for the global load of all the bolts. 44 B.3 Manual uncontrolled tightening . 45 B.4 Assembly using torque wrench . 45 B.5 Assembly using bolt tensioner . 46 Annex C (informative)
Flange rotations . 48 C.1 General . 48 C.2 Use of flange rotation. 48 C.3 Calculation of flange rotations . 48 Annex D (informative)
Use of the calculation method . 50 D.1 Calculation method principle . 50 D.2 Mechanical model . 51 D.3 Required checks . 52 D.4 Calculation sequence. 52 Annex E (informative)
Gasket/flange face friction coefficients examples . 54 Annex F (normative)
Determination of ∆eGc,I based on a given PQR . 55 F.1 Determination of the deflection occurring during a PQR test . 55 F.2 Determination of the deflection to be taken into account in the calculation . 56 Annex G (informative)
Sealing gasket parameter when no leakage rate is specified . 57 Annex H (informative)
Alternative calculation procedure taking into account the plastic deformation of the gasket in subsequent load conditions procedures (after assembly) . 58 H.1 Introduction . 58 H.2 Calculation procedure. 58 H.2.1 General description . 58 H.2.2 No additional plastic deformation . 59 H.2.3 Additional plastic deformation . 59 H.3 Flat gaskets . 59 H.3.1 Flat gaskets with small or median deformations . 59 H.3.2 Flat gaskets with greater deformations . 61 H.4 Metal gaskets with curved surfaces (Figures 3b, c, e, f ) . 62 H.5 Metal gaskets with octagonal section (Figure 3d) . 62 Annex I (informative)
Available, incomplete models for conversion of the leakage rates in different conditions (based on certain flow models) . 63 I.1 Introduction and warning . 63 I.2 Flow theory fundamentals . 63 I.2.1 Transport modes . 63 I.2.2 Case of gases . 64 I.2.3 Case of liquids: Parallel capillary model. 65 I.3 Factors of influence on the leakage rate of gaskets and gasketed joints . 65 I.3.1 List of identified factors . 65 I.3.2 Limits and restriction of the proposed models . 65 I.3.3 Dependence on pressure . 66 I.3.4 Dependence on temperature . 67 SIST EN 1591-1:2014
EN 1591-1:2013 (E) 4 I.3.5 Dependence on the type of fluid . 68 I.3.6 Influence of the gasket thickness . 68 I.3.7 Influence of gasket width . 69 I.3.8 Influence of gasket stress . 69 I.3.9 Influence of other factors . 69 I.3.10 Conclusion on the factors of influence . 70 I.4 Practical application for EN 1591-1 calculations . 70 I.4.1 General . 70 I.4.2 Determination of a trend for the leakage rate for the flange connection in “actual” from “reference” conditions . 71 I.4.3 Determination of a trend for the leakage rate for the flange connection in “reference” from “actual” conditions . 72 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 97/23/EC . 74 Bibliography . 75
SIST EN 1591-1:2014
EN 1591-1:2013 (E) 5 Foreword This document (EN 1591-1:2013) has been prepared by Technical Committee CEN/TC 74 “Flanges and their joints”, the secretariat of which is held by DIN. 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 June 2014, and conflicting national standards shall be withdrawn at the latest by June 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 1591-1:2001+A1:2009. The major changes in comparison with the previous edition include: correction of load ratio calculation for blind flanges; integration of spacers (washers); modification of bolt load ratio calculation; integration of lateral forces and torsion moments applied on the bolted joint; integration of an alternative calculation method (more precise) for the determination of the gasket effective width (informative annex); integration of the possibility to handle gasket creep/relaxation behaviour through additional deflection; integration of an informative annex concerning leakage rates conversions; integration of the possibility to check a bolted flange connection for a specified initial bolt load value; integration of the possibility to perform a calculation even when no tightness requirement is defined through basic gasket parameters
(Annex G). 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(s), 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 EN 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 SIST EN 1591-1:2014
EN 1591-1:2013 (E) 6 CEN/TR 1591-5, Flanges and their joints — Design rules for gasketed circular flange connections — Part 5: Calculation method for full face gasketed joints 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. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
SIST EN 1591-1:2014
EN 1591-1:2013 (E) 7 1 Scope This European Standard 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. 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, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 13555:2004, Flanges and their joints — Gasket parameters and test procedures relevant to the design rules for gasketed circular flange connections 3 Notation 3.1 Use of figures 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. NOTE 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 Type 12
Figure 13 Type 13
Figure 14 Type 21
Figures 6 to 9
3.2 Subscripts and special marks 3.2.1 Subscripts A – Additional (FA, MA) B – Bolt SIST EN 1591-1:2014
EN 1591-1:2013 (E) 8 C – Creep of gasket (∆eGc) 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 (FLI) M – Moment N – Nut P – Fluid pressure Q – Net axial force due to pressure R – Net axial force due to external force S – Shell, shear
T – Shell, modified TG – Torsion (MTG) X – Flange weakest cross section W – Washer ∆ – Symbol for change or difference av – average c – calculated d – design
e – effective i – Interim value max – maximum min – minimum nom – nominal opt – optimal req – required SIST EN 1591-1:2014
EN 1591-1:2013 (E) 9 s – non-threaded part of bolt specified – refers to the case of calculation performed for a given (specified) initial bolt load t – theoretical, torque, thread 0 – initial bolt-up condition (I = 0, see subscript I) 3.2.2 Special marks ~ – Accent placed above symbols of flange parameters that refers to the second flange of the joint, possibly different from the first.
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], Formula (41) AF, AL Gross radial cross-section area (including bolt holes) of flange ring, loose flange [mm2], Formulae (10), (13) and (16) AGe, AGt Gasket area, effective, theoretical [mm2], Formulae (56), (53) AQ Effective area for the axial fluid-pressure force [mm2], Formula (90) EB, EF, EL EW Modulus of elasticity of the part designated by the subscript, at the temperature of the part [MPa] EG, Modulus of elasticity of the gasket for unloading/reloading at the considered temperature, considering the initial compressed thickness [MPa]
FA Additional external axial force [N], tensile force > 0, compressive force < 0, see Figure 1, Formulae (92) and (96) FB Bolt force (sum of all bolts) [N] FG Gasket force [N] FG∆,
Minimum gasket force in assembly condition [N] that guarantees, after all load changes, to subsequent conditions the required gasket force, Formulae (105), (106)
FL Force resulting from the additional radial forces [N], Formula (93) and (104) FQ Axial fluid-pressure force [N], Formula (91) FR Force resulting from the additional external loads [N], Formula (96) FX, FY, FZ Additional forces along X, Y and Z-axis at gasket interface [N], Formulae (92) and (93) I Load condition identifier, for assembly condition I = 0, for subsequent conditions I = 1, 2, 3,. MA Resulting external bending moment [N × mm], Figure 1, Formula (94) and (104) Mt Bolt assembly torque [N × mm], Formula (B.4) SIST EN 1591-1:2014
EN 1591-1:2013 (E) 10 Mt,B Twisting moment [N × mm] applied to bolt shanks as a result of application of the bolt assembly torque Mt, Formula (B.9) MTG Additional external torsion moment due to friction, Formula (95) and (104) NR Number of re-assemblies and re-tightenings during service life of joint, Formulae (119), (2) P Pressure of the fluid [MPa], internal pressure > 0, external pressure < 0 (1 bar = 0,1 MPa), Formula (91) NOTE P in this standard is equal to the maximum allowable pressure PS according to the PED. PQR Creep factor which is the ratio of the residual and the original gasket surface pressure at load conditions [-] (Annex F). QG Mean effective gasket compressive stress [MPa], QG = FG/AGe (57) QA Gasket surface pressure at assembly prior to the unloading which is necessary for the validity of the corresponding Qsmin (L)I in all subsequent conditions [MPa], Formula (103).The lowest acceptable value for QA is Qmin (L) from EN 13555. Q0,min Gasket surface pressure required at assembly prior to the unloading when no specific leak rate is requested [MPa], replacement of QA in Formula (103), Annex G Qmi
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