EN ISO 27509:2012

SLOVENSKI STANDARD
01-januar-2014
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Petroleum and natural gas industries - Compact flanged connections with IX seal ring
(ISO 27509:2012)
Erdöl- und Erdgasindustrie - Kompakte Flanschverbindungen (ISO 27509:2012)
Industries du pétrole et du gaz naturel - Raccordements à brides compactes avec bague
d'étanchéité IX (ISO 27509:2012)
Ta slovenski standard je istoveten z: EN ISO 27509:2012
ICS:
23.040.60 Prirobnice, oglavki in spojni Flanges, couplings and joints
elementi
75.180.01 Oprema za industrijo nafte in Equipment for petroleum and
zemeljskega plina na splošno natural gas industries in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 27509
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2012
ICS 23.040.60
English Version
Petroleum and natural gas industries - Compact flanged
connections with IX seal ring (ISO 27509:2012)
Industries du pétrole et du gaz naturel - Raccordements à Erdöl- und Erdgasindustrie - Kompakte
brides compactes avec bague d'étanchéité IX (ISO Flanschverbindungen mit IX Dichtungsring (ISO
27509:2012) 27509:2012)
This European Standard was approved by CEN on 18 December 2012.

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

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 27509:2012: E
worldwide for CEN national Members.

Contents Page
Foreword . 3
Foreword
This document (EN ISO 27509:2012) has been prepared by Technical Committee ISO/TC 67 “Materials,
equipment and offshore structures for petroleum, petrochemical and natural gas industries” in collaboration
with Technical Committee CEN/TC 12 “Materials, equipment and offshore structures for petroleum,
petrochemical and natural gas industries” the secretariat of which is held by AFNOR.
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 2013, and conflicting national standards shall be withdrawn at
the latest by June 2013.
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.
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, 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.
Endorsement notice
The text of ISO 27509:2012 has been approved by CEN as a EN ISO 27509:2012 without any modification.

INTERNATIONAL ISO
STANDARD 27509
First edition
2012-12-15
Petroleum and natural gas industries —
Compact flanged connections with IX
seal ring
Industries du pétrole et du gaz naturel — Raccordements à brides
compactes avec bague d'étanchéité IX

Reference number
ISO 27509:2012(E)
©
ISO 2012
ISO 27509:2012(E)
©  ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
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Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 27509:2012(E)
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms, definitions, symbols and abbreviated terms .2
3.1 Terms and definitions .2
3.2 Symbols.2
3.3 Abbreviated terms .4
4 Design.5
4.1 General .5
4.2 Design principles.5
4.3 Assembly requirements.6
4.4 Standard components.7
4.5 Units of measurements.8
4.6 Rounding.8
4.7 Compliance with piping design codes .8
4.8 Compliance to this International Standard.8
5 Designation .8
5.1 Designation of flanges.8
5.2 Designation of seal rings.9
6 Materials .9
6.1 General .9
6.2 Flange materials .9
6.3 Bolting materials .10
6.4 Seal ring materials.11
7 Strength, pressure/temperature ratings and leak tightness.11
7.1 General .11
7.2 Pressure/temperature ratings .12
7.3 Pressure testing and leak tightness.12
8 Dimensions of flanges .13
8.1 General .13
8.2 Weld neck (WN) dimensions .14
8.3 Blind flange (BL) dimensions.21
8.4 Integral flange (IF) dimensions .24
8.5 Rigid interface (RI) dimensions .31
8.6 Dimensions of paddle blanks (PB) and paddle spacers (PS) .34
8.7 Handle and lifting lugs.37
8.8 Dimensions of orifice spacers (OS).38
8.9 Dimensions of reducing threaded flanges (RTs) .39
8.10 Auxiliary connections .40
8.11 Flange tolerances .40
8.12 Surface finish.42
9 Marking of flanges.42
9.1 Flanges other than integral flanges.42
9.2 Manufacturer's name or trademark .43
9.3 Nominal size.43
9.4 Pressure class designation.43
ISO 27509:2012(E)
9.5 Pipe dimensions .43
9.6 Material designation .43
9.7 Identification of internally threaded flanges .43
9.8 Material traceability .44
9.9 Marking examples.44
9.10 Stamping.44
10 Dimensions of seal rings .44
11 Inspection and testing of seal rings .48
12 Coating and colour coding .48
13 Marking of seal rings.48
14 Quality management systems.48
15 Bolt dimensions and masses .48
Annex A (normative) Pressure temperature ratings and shear capacity of seal rings.49
Annex B (informative) Integral flange angle selection .54
Annex C (informative) Quality management system .64
Annex D (normative) Bolt dimensions and masses .65
Annex E (informative) Handling, installation, assembly and repair of flanges.71
Annex F (informative) Mass of flanges.84
Annex G (informative) Metric bolting .95
Annex H (informative) Additional information on bibliographical references .97
Bibliography .98

iv © ISO 2012 – All rights reserved

ISO 27509:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 27509 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries, Subcommittee SC 6, Processing equipment and
systems.
ISO 27509:2012(E)
Introduction
[36]
This International Standard, which is based on NORSOK L-005 , has been developed to provide a standard
for compact flanged connections (CFCs) that constitutes an alternative to conventional flanges as specified in
ASME standards, European Standards and other International Standards, with reduced mass and smaller
overall dimensions, as well as increased reliability in leak tightness by means of its inherent design features
and make up procedures. CFCs can also provide an alternative to other types of clamp and hub type
mechanical connectors.
The use of load carrying sealing elements, traditionally referred to as "gaskets", does not comply with the
fundamental requirements of this International Standard.
This International Standard has been developed for use in process piping systems, which are designed
according to codes for pressure piping, e.g. ASME B31.3. See 4.7 for more details.
The flange designs have been selected to achieve a minimum safety factor of 2,0 when subjected to a design
pressure equal to ASME B16.5 pressure temperature ratings within the temperature limits of this International
Standard.
The main body of this International Standard contains all necessary information on how to manufacture and
supply flange and seal ring materials, such as
⎯ flange dimensions and material requirements;
⎯ seal ring dimensions and material requirements;
⎯ bolting dimensions and material requirements;
⎯ requirements to tolerances and surface finish;
⎯ requirements to designation and marking of finished products.
Normative annexes A and D cover the following topics:
⎯ structural capacity equations for flange assemblies;
⎯ bolt dimensions and masses.
Informative annexes B, C, E, F and G cover the following topics:
⎯ how to apply the flanges to special geometries of valves and equipment nozzles;
⎯ quality management;
⎯ installation and assembly instructions, and guidelines on how to repair damage and irregularities on
sealing surfaces;
⎯ masses of all standard components;
⎯ suitable dimensions of alternative metric bolting.
vi © ISO 2012 – All rights reserved

ISO 27509:2012(E)
For the purposes of this International Standard, the following verbal forms apply:
⎯ "shall" indicates a requirement strictly to be followed in order to conform to this International Standard and
from which no deviation is permitted, unless accepted by all involved parties;
⎯ "should" indicates that among several possibilities one is recommended as particularly suitable, without
mentioning or excluding others, or that a certain course of action is preferred but not necessarily required;
⎯ "may" indicates a course of action permissible within the limits of this International Standard;
⎯ "can" is used for statements of possibility and capability, whether material, physical or casual.

INTERNATIONAL STANDARD ISO 27509:2012(E)

Petroleum and natural gas industries — Compact flanged
connections with IX seal ring
1 Scope
This International Standard specifies detailed manufacturing requirements for circular steel and nickel alloy
compact flanged connections and associated seal rings, for designated pressures and temperatures in class
designations CL 150 (PN 20) to CL 1500 (PN 260) for nominal sizes from DN 15 (NPS ½) to DN 1200
(NPS 48), and for CL 2500 (PN 420) for nominal sizes from DN 15 (NPS ½) to DN 600 (NPS 24).
NOTE NPS is in accordance with ASME B36.10M and ASME B36.19M.
This International Standard is applicable to welding neck flanges, blind flanges, paddle spacers and spacer
blinds (paddle blanks), valve/equipment integral flanges, orifice spacers, reducing threaded flanges and rigid
interfaces for use in process piping for the petroleum, petrochemical and natural gas industries.
This International Standard is applicable within a temperature range from −196 °C to +250 °C.
This International standard is not applicable for external pressure.
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.
ISO 2768-1, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
ISO 4288, Geometric Product Specifications (GPS) — Surface texture: Profile method — Rules and
procedures for the assessment of surface texture
ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-
section conduits running full — Part 1: General principles and requirements
ISO 5167-2:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 2: Orifice plates
ISO 14313, Petroleum and natural gas industries — Pipeline transportation systems — Pipeline valves
ISO 80000-1:2009, Quantities and units — Part 1: General
ASME B16.5, Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
ASME B16.34, Valves — Flanged, Threaded and Welding End
ASME B1.20.1, Pipe Threads, General Purpose (Inch)
ASME B31.3, Process Piping
ISO 27509:2012(E)
EN 1092-1, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories, PN
designated — Part 1: Steel flanges
EN 1779, Non-destructive testing — Leak testing — Criteria for method and technique selection
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
class
CL
ASME pressure class in accordance with ASME B16.5 and ASME B16.34
3.1.2
compact flanged connection
CFC
non-gasketed bolted static pipe connection including two flanges and where the bolt loads are transferred
through metal to metal contact between the flange faces
3.1.3
gasket
barrier to prevent the passage of fluids, but which does transmit all loads between flanges
EXAMPLE As shown in EN 1591-1:2001, Figure 3.
3.1.4
purchaser
individual or organization that buys the pipe connection on behalf of the user and/or operator or for its own use
3.1.5
seal
component providing a barrier to prevent the passage of fluids, transmitting no significant loads between the
flanges
3.1.6
supplier
individual or organization that takes the responsibility for the supply of the pipe connection and its
conformance with this International Standard
3.2 Symbols
A outside diameter of neck
A maximum outer diameter to accommodate standard tools
max
A minimum neck outer diameter listed in Table 7 to Table 12
min
Area cross-sectional area of the neck/pipe calculated from t
015 015
Area cross-sectional area of a special flange neck geometry calculated from t
eqv eqv
B bore diameter, where the bore should not exceed the maximum listed bore in this International
Standard
B maximum listed bore diameter
max
2 © ISO 2012 – All rights reserved

ISO 27509:2012(E)
B minimum bore diameter for which the face angles are valid
min
B1 minimum bore diameter for flange to be blinded
NOTE B1 is also the start diameter for blind and reducing threaded flange face angles.
BCD bolt circle diameter
d bolt size
B
d average diameter of neck end = (A+B)/2
p
DA1 internal diameter of groove
DA3 outer diameter of groove
DG4 seal ring seal diameter
DW1 inner recess diameter
DW2 outer recess diameter
DW3 outside diameter of flange
DW4 flange to neck fillet outer diameter
e radial distance between BCD and d
p
e (DW3 + DW2)/4 – BCD/2
B
e (DW3 + DW2)/4 –(A+B)/4
p
E1 depth of groove
E2 depth of recess
E3 depth of recess for gasket
F applied axial force
A
F bolt total plastic capacity (root area × number of bolts × yield strength)
cB
F flange axial load capacity without effect of bolt prying
f
F flange axial load capacity including the effect of bolt prying
fP
F end cap force calculated to seal ring seal diameter
end
F resulting force from external tension force F and external bending moment M
R A A
f flange material yield strength at temperature
y
HP1 thickness of PB, PS and OS
HW3 flange thickness
HW5, HT5 overall length
L bolt hole diameter
L1,L2,L3 bolt hole depths
M applied bending moment
A
n number of bolts
p internal pressure in N/mm
ISO 27509:2012(E)
RA radius
RB radius
RC radius (maximum value tabulated)
RV1 neck to flange ring radius on integral flanges
t pipe wall thickness
t minimum neck thickness that can be used which is defined by the standard pipe outer diameter,
min
A, and maximum listed bore diameter, B .
max
t the maximum neck thickness that can be used which is defined by A and the minimum listed
max max
bore diameter
t the wall thickness giving the smallest possible face angle (0,15°)
t the wall thickness calculated from a special flange neck geometry
eqv
X half major ellipse axis
Y half minor ellipse axis
αA2 groove angle
αB1 flange face bevel angle
αB2 effective face angle/rear face bevel angle
ψ flange utilization ratio
3.3 Abbreviated terms
BL blind flange
CFC compact flanged connection
CL class
DN nominal pipe diameter (expressed in millimetres)
ID internal diameter
IF integral flange (as part of some other equipment or component)
IX special metallic seal ring applied in Clause 4
LB line blinds (including PS and PB)
NPS nominal pipe size (expressed in inches)
OD outer diameter
OS orifice spacer
PB paddle blank
PN nominal pressure (bar)
PS paddle spacer
PTFE polytetrafluoroethylene
RI rigid interface
4 © ISO 2012 – All rights reserved

ISO 27509:2012(E)
RT reducing threaded flange
WN weld neck
4 Design
4.1 General
In order to be compliant with this International Standard, CFCs fulfil the minimum design requirements
outlined below.
⎯ They have been designed for face-to-face make-up for transfer of the bolt loading through the flange
faces.
⎯ They have been designed so that a static mode is maintained in the bolted joint up to 1,5 times the
specified pressure/temperature rating, see 7.2. Static mode is maintained as long as the difference
between maximum and minimum nominal stress sustained by the bolts in the joint does not exceed 5 %
of the minimum values specified in Table 3.
⎯ They have been standardized to cover as a minimum the same pressure temperature class designations
and sizes as can be found in ASME B16.5 with equal or better performance.
⎯ They have been standardized to fit with commonly used standards by the valve industry (e.g. ASME
B16.34, ISO 14313 and the EN 12516 series of parts), and other valve standards which make reference
to these standards for pressure design.
⎯ The weakest part of flanged connections according to this International Standard regarding fatigue failure
is always located somewhere in the transition from flange to pipe or flange to nozzle neck of an
equipment or valve. The bolted joint itself is never subjected to fatigue load if considerations to cycling
temperatures are taken when selecting bolt material, see 6.3.
4.2 Design principles
Figure 1 shows the design principles of compact flanges and its seal system according to this International
Standard.
The flange face includes a slightly convex bevel with the highest point, called the heel, adjacent to the bore
and a small outer wedge around the outer diameter of the flange. The assembly is made up by
tightening/tensioning the flange bolting which pulls the two connector halves together. The bevel angles have
been standardized for different and relevant adjoining pipe wall thicknesses for each welding neck flange of a
given size and pressure class.
For the IX seal ring, axial forces are exerted on the taper of the metal seal ring and translated into a radial
sealing force. Furthermore with increased pre-load, the bevel is closed and face to face contact is achieved at
the outer wedge while most of the bolt pre-load is transferred as compressive forces between the flange faces
at the heel, as illustrated in Figure 1. The arrows in the figure indicate the applied forces/pressure and the
contact forces after make-up and during normal operation.
The principle design of the flange face includes two independent seals. The first seal is created by application
of seal seating stress at the flange heel. However, an undamaged flange heel may not seal at any extreme
load condition, but the heel contact will be maintained for pressure values up to 1,5 times the flange pressure
rating at room temperature for any combination of WN flange and a corresponding pipe within given limits of
pipe wall thicknesses in tables of dimensions. This requirement is only applicable when the WN thickness
fulfils the code requirement for minimum pipe wall thickness for the actual material. The main seal is the IX
seal ring. The seal ring force is provided by the elastic stored energy in the stressed seal ring. Any heel
leakage will give internal pressure acting on the seal ring inside intensifying the sealing action.
ISO 27509:2012(E)
The design aims at preventing exposure to oxygen and other corrosive agents in the way that adjoining
flanges remain in contact along their outer circumference for all allowable load levels. Thus, this prevents
corrosion of the flange faces, the stressed length of the bolts and the seal ring.
The back face of the flange in the made-up position is parallel to the flange face in order to prevent bending of
the bolts in the assembled condition.

a)  Before assembly b)  Completed assembly c)  Design loads
Key
1 Wedge 6 Weld neck flange
2 Stud 7 Bolt clamping force
3 Nut 8 Hydrostatic end force plus external loads
4 IX seal ring 9 Fluid pressure
5 Heel
Figure 1 — Design principles of standard compact flange assemblies
4.3 Assembly requirements
In order to comply with the design principles as described in 4.2 it is mandatory to assemble the flanged
connections to target bolt loads according to Table 1 below. For detailed advice on how to assemble compact
flanges, see Annex E.
NOTE Compact flange IX seal rings require sufficient flexibility to enable seal ring size entrance and removal. The
required spacing needs to be considered during piping design and layout to ensure necessary flexibility in the piping
systems.
6 © ISO 2012 – All rights reserved

ISO 27509:2012(E)
Table 1 — Target residual preload for bolt materials used to assemble compact flanges to this
International Standard
Stud bolt size Target residual preload
in kN
½-UNC 44
⅝-UNC 71
¾-UNC 106
⅞-UNC 147
1-UNC 193
1 ⅛-8UN 255
1 ¼-8UN 325
1 ⅜-8UN 405
1 ½-8UN 492
1 ⅝-8UN 589
1 ¾-8UN 693
1 ⅞-8UN 807
2-8UN 929
2 ¼-8UN 1199
2 ½-8UN 1503
2 ¾-8UN 1667
3-8UN 2004
3 ¼-8UN 2373
3 ½-8UN 2773
3 ¾-8UN 3204
4-8UN 3666
4.4 Standard components
The types of flanges covered by this International Standard are given in Table 2.
Table 2 — Types of flanges and accepted raw material forms for manufacture
Type Description Raw material product forms
WN Weld neck flange Forged to shape
BL Blind flange Plate or forged to shape
IF Forging, forged bar (maximum DN 50) or casting
Integral flange as part of some other equipment or
component
RI Rigid interface as part of some other equipment or Plate, forging or casting
component
PB Paddle blank Plate or forged to shape
PS Paddle spacer Plate or forged to shape
OS Orifice spacer Plate or forged to shape
RT Reducing threaded flange Plate or forged to shape
ISO 27509:2012(E)
4.5 Units of measurements
In this International Standard, data are expressed in both SI units and USC units. For a specific order item,
unless otherwise stated, only one system of units shall be used, without combining data expressed in the
other system.
For data expressed in SI units, a comma is used as the decimal separator and a space is used as the
thousands separator. For data expressed in USC units, a dot (on the line) is used as the decimal separator
and a comma is used as the thousands separator.
4.6 Rounding
Except as otherwise required by this International Standard, to determine conformance with the specified
requirements, observed or calculated values shall be rounded to the nearest unit in the last right-hand place of
figures used in expressing the limiting value, in accordance with the rounding method of ISO 80000-1:2009,
Annex B, Rule A.
4.7 Compliance with piping design codes
Although not listed as a component standard in ASME B31.3, all components contained in this International
Standard fulfil the requirements for unlisted piping components in paragraph 302.2.3 in ASME B31.3. This is
based on full compliance with paragraph 304.7.2 (a), (b), (c) and (d):
a) The service experience requirement is fulfilled because this type of CFC has been widely used in the
North Sea since 1990. The service experience covers the complete size range covered by this
International Standard.
b) The experimental stress analysis requirements is fulfilled since a number of tests on strain gauged test
specimens have been run over the years. Reference is made to References [40] to [43], [50], [51] and [52].
c) The proof test requirements are fulfilled since a number of pressure tests have been performed over the
years. In addition to tests referenced under (b), reference is made to References [38], [44] and [45].
d) Compact flanged connections to this International Standard were originally developed and designed using
the design by analysis method to pre 2007 issue of ASME VIII div.2, appendix 4 and appendix 6. Specific
requirements may apply to components designed by analysis, depending on the applied piping design
code. Such requirements normally include impact testing at a defined temperature relative to the
minimum design temperature and a specified extent of non-destructive testing.
4.8 Compliance to this International Standard
The manufacturer shall be responsible for complying with all of the applicable requirements of this
International Standard. It shall be permissible for the purchaser to make any investigation necessary in order
to be assured of compliance by the manufacturer and to reject any material that does not comply.
5 Designation
5.1 Designation of flanges
The following shall designate the flanges in accordance with EN 1092-1:
⎯ flange type abbreviation according to Table 2;
⎯ number of this International Standard;
⎯ nominal flange size (DN);
8 © ISO 2012 – All rights reserved

ISO 27509:2012(E)
⎯ pressure class designation;
⎯ pipe dimensions:
⎯ for standard pipes, the wall thickness in mm to one decimal accuracy;
⎯ for non-standard pipes, the pipe bore and wall thickness.
⎯ material designation.
The designation elements shall be separated by a slash. The number of characters is not fixed.
Examples of designation are given below:
EXAMPLE 1 Designation of WN flange in CL 600, nominal size DN 250 with pipe schedule 40S, i.e. 9,3 mm wall
thickness and material ASTM A182F51 (duplex):
WN/ISO 27509/DN250/CL600/9.3/A182F51
EXAMPLE 2 For designation of a BL flange in CL 2500, nominal size DN 200 and with material ASTM A516 Grade 70
(low temperature carbon steel):
BL/ISO 27509/DN200/CL2500/A516Grade70
EXAMPLE 3 Designation of an RT flange in CL900, nominal size DN 25, threaded outlet specified (0,5 inch NPT is
default, see 8.9), and with material ASTM A182F316 (stainless steel):
RT/ISO 27509/DN25/CL900/0,5”NPT/A182F316
5.2 Designation of seal rings
The IX seal ring shall be designated as described below:
⎯ number of this International Standard;
⎯ type - and ring size - IX and the appropriate DN;
⎯ material designation.
The designation elements shall be separated by “/” (slash). The number of characters is not fixed.
EXAMPLE Designation of an IX seal ring for DN 250 and material ASTM A182F51 (Duplex):
ISO 27509/IX250/A182F51
6 Materials
6.1 General
Criteria for the selection of materials suitable for a particular fluid service are not part of this International
Standard.
6.2 Flange materials
Flanges covered by this International Standard shall be made from base material product forms as listed in
Table 2. The standardized bevel angle as described in 4.2 is applicable for steel and nickel alloys, which are
covered in this International Standard.
ISO 27509:2012(E)
It is assumed that the flange material has a Young's modulus in the range 190 000 MPa to 210 000 MPa at
room temperature. Minimum specified yield strength for flanges to this International Standard is 205 MPa at
room temperature.
The elliptical transition between flange ring and flange neck of WN flanges, and the corresponding crotch
transition of IF flanges shall be subject to 100 % surface examination irrespective of flange material.
Examination method and acceptance criteria shall be according to standards referenced in the applied Piping
Design Code.
Cast flanges shall be non-destructive tested to comply with casting factor used in calculations to determine
performance. In general cast flanges used as IF should be examined by 100 % surface and volumetric control
in order to obtain a casting factor of 1,0, and thus obtaining the minimum pressure and temperature ratings
stated in Clause 7. Examination and acceptance criteria shall be agreed between purchaser and manufacturer,
but sealing surfaces shall satisfy requirements in 8.12.
Test samples for certification testing required by the material standard, shall be taken from the flange ring
transverse to the dominant grain flow direction, or alternatively in both axial (weld neck) and tangential (flange
ring) direction relative to internal bore.
No repair welding is accepted in the elliptical transition for the WN flange (see Figure 2) as well as in the
crotch radius for the IF (see Figure 4) manufactured in line with this International Standard.
6.3 Bolting materials
The minimum bolt yield strength at temperature shall be in accordance with Table 3. Linear interpolation can
be used to calculate minimum yield strength for intermediate temperatures.
Table 3 — Minimum bolt yield strength as function of maximum design temperature, T
des
Bolt T ≤ 20 °C T = 50 °C T = 100 °C T = 150 °C T = 200 °C T = 250°C
des des des des des des
nominal
diameter, d
B
d ≤ 2 ½” 725 MPa 713 MPa 672 MPa 648 MPa 632 MPa 613 MPa
2 ½” < d ≤ 4” 655 MPa 645 MPa 607 MPa 586 MPa 569 MPa 555 MPa
Bolt pre-load requirements described in Table 1 are based upon these requirements and so are the flange
face angles and groove dimensional details.
Nuts shall have sufficient strength to carry 100 % of the bolt capacity defined by the specified minimum yield
strength as listed above, and the thread stress area, see NOTE. Thread tolerances shall be considered in the
nut strength evaluation.
NOTE Nuts to ISO 898-2 should not be used in order to reduce the risk of nut thread stripping.
Imperial or metric standard bolts threaded at both ends or full length may be used. Hex nuts with a minimum
height equal to one nominal bolt diameter shall be used. The choice of bolt thread standard may affect
assembly and bolt preloading procedures. Annex E is based on imperial bolting dimensions, while Annex G
describes which metric bolts to choose for replacing the listed imperial bolts.
The effects of differential thermal expansion and bolt relaxation could affect the functionality of the joint up to
loss of preload. Care shall be taken by selecting an appropriate bolt material for the above effects. Within the
maximum temperature limits of this International Standard, it is acceptable to use low alloy steel bolting in
combination with austenitic stainless steel flange materials. In such applications, washers shall be applied
under the nuts in order to avoid indenting the nut into the flange which would cause loss of pre-load.
Washers shall be in same or equivalent grade of material as the nuts and should be through hardened.
10 © ISO 2012 – All rights reserved

ISO 27509:2012(E)
Relaxation is not regarded to be of any importance for this flange standard since the maximum design
temperature is 250 °C. A margin of 5 % points was used on bolt pre-load when documenting the flange
standard to the functionality requirements in Clause 4, meaning the FEAs were performed with 70 % bolt yield
as pre-load over the 75 % specified as target residual pre-load in Table 1. The 5 % point reduction was
applied to account for uncertainties in pre-loading procedures and any long term relaxation.
6.4 Seal ring materials
Typical minimum yield stress and ultimate tensile stress for the seal ring material shall at maximum design
temperature be 300 MPa and 360 MPa, respectively, in order to allow for reasonably elastic spring-back.
The user is responsible for selecting a seal ring material which is suitable for the service medium and the
design temperature conditions.
There is no requirement for Charpy impact testing of seal ring materials.
Seal rings shall be made of forged or worked material. For in service use, Table 4 gives a guideline for seal
ring selection and temperature limitations.
Table 4 — Seal ring selection
Flange material Service temperature Seal ring material
Typical manufacturing
standard
(Fine grained) carbon steel -50 °C to +250 °C Carbon steel or low alloy ASTM A788 or equivalent
steels, e.g. CS360LT or
AISI 4140
Stainless steel -50 °C to +250 °C 22Cr Duplex ASTM A182 or equivalent
Stai
...