CEN/TC 74/WG 10 - Calculation methods

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.).

This Technical Report gives guidance for the calculation of full face gasketed joints on the basis of the calculation method given in EN 1591-1.

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

This Report provides technical background information on EN 1591-1.

This document gives background information for guidance to be used in conjunction with the calculation method for design rules for gasketed circular flange connections as specified in FprEN 1591-1:2024.
NOTE   References to formulae numbered in this document have a decimal format whilst those in FprEN 1591-1:2024 are indicated by whole numbers.

2006 12 19 Tolerance of 6 months requested before formal vote per CEN/TC 74 res. 263/2006.
Tolerance of up to nine months before enquiry (TC resolution CEN/TC 74 C 245/2004) (Note by SV on 2005-02-10)

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.).

TC - Contains the modifications due to the prior corrigendum EN 1591-1:2001+A1:2009/AC:2010; contains a new change to be made in Subclause 6.5 in EN 1591-1:2001+A1:2009; modifications to be implemented in the three language versions of EN 1591-1:2001+A1:2009.
2013: Originator of XML version: first setup pilot of CCMC in 2012

1.1   General
This European Standard defines a Calculation method for bolted, gasketed, circular flange joints. Its purpose is to ensure structural integrity and control of leaktightness. The following equations use gasket parameters based on definitions and test methods specified in EN 13555.
1.2   Requirement for use of the Calculation method
Where permitted, the Calculation method is an alternative to design validation by other means e.g.
- special testing;
- proven practice;
- use of standard flanges within permitted conditions.
1.3   Validity
1.3.1   Geometry
The Calculation method is applicable to the configurations having:
-   flanges whose section is given or may be assimilated to those given in Figures 4 to 12;
-   four or more identical bolts uniformly distributed;
-   gasket whose section and configuration after loading can be assimilated by one of those given in Figure 3;
-   flange dimension which meet the following conditions:
a)   0,2 ≤ bF/eF ≤ 5,0; 0,2 ≤ bL/eL ≤ 5,0
b)   eF ≤ max {e2; dB0; pB x  }
c)   
NOTE   For explanations of symbols see clause 3.
NOTE   The condition bF/eF ≤ 5,0 need not be met for collar in combination with loose flange.
NOTE   The condition   is for limitation of non-uniformity of gasket pressure due
to spacing of bolts. The values 0,01 and 0,10 are to be applied for soft (non-metallic) and hard (metallic)
gaskets respectively. A more precise criterion is given in annex A.
NOTE   Attention may need to be given to the effects of tolerances and corrosion on dimensions; reference should be made to other codes under which the calculation is made, for example values are given in EN 13445 and EN 13480.
The following configurations are outside the scope of the Calculation method:
- flanges of essentially non-axisymmetric geometry, e.g. split loose flanges, web reinforced flanges;

2009-12-21 EMA: Corrigendum created following resolution 282/2009 taken on 2009-12-04.
TC - Correction of various symbols and equations in Clauses 3, 4, 5, 6 and in Annex E - Mechanical engineering

1.1  General
This European Standard defines a Calculation method for bolted, gasketed, circular flange joints. Its purpose is to ensure structural integrity and control of leaktightness. ENV 1591-2 gives values for gasket properties which can be used in the Calculation method.
1.2  Requirement for use of the Calculation method
Where permitted, the Calculation method is an alternative to design validation by other means e.g.
  special testing;
  proven practice;
  use of standard flanges within permitted conditions.
1.3  -Validity
1.3.1  Geometry
The Calculation method is applicable to the configurations having:
flanges whose section is given or may be assimilated to those given in Figures 4 to 12;
four or more identical bolts uniformly distributed;
gasket whose section and configuration after loading can be assimilated by one of those given in Figure 3;
flange dimension which meet the following conditions:
a) 0,2   bF/eF   5,0; 0,2   bL/eL   5,0
b)
e sub FUNC F ~>=~max ~LEFT LBRACE e sub 2;~ d sub { FUNC B0};~  p sub FUNC B ~ × ~ NROOT 3 {(0,01...0,10) ~ × ~ p sub FUNC B / b sub FUNC F } RIGHT RBRACE                                                  
c) cos s   1/(1 + 0,01 ds/es)
NOTE 1    For explanations of symbols see clause 3.
NOTE 2   The condition bF/eF   5,0 need not to be met for collar in combination with loose flange.
NOTE 3   The condition  
is for limitation of non-uniformity of gasket pressure due to spacing of bolts. The values 0,01 and 0,10 are to be applied for soft (non-metallic) and hard (metallic) gaskets respectively. A more precise criterion is given in annex A.
NOTE 4   Attention may need to be given to the effects of tolerances and corrosion on dimensions; reference should be made to other codes under which the calculation is made, for example values are given in EN 13445 and EN 13480.

This European Prestandard specifies gasket parameters for use in EN 1591-1.
WARNING   The reader is directed to obtain gasket parameters for use in the calculation method given in EN 1591-1 from the
gasket supplier. Where this is not possible, then the values in this document may be used. In the latter case the reader should
ensure the latest version of this document is used. If in doubt the national CEN member can be contacted.