SIST EN ISO 27509:2021

SLOVENSKI STANDARD
01-februar-2021
Nadomešča:
SIST EN ISO 27509:2014
SIST EN ISO 27509:2014/AC:2014
Industrija za predelavo nafte in zemeljskega plina - Kompaktni prirobnični
konektorji s tesnilnim obročem IX (ISO 27509:2020)
Petroleum and natural gas industries - Compact flanged connections with IX seal ring
(ISO 27509:2020)
Erdöl- und Erdgasindustrie - Kompakte Flanschverbindungen mit IX Dichtungsring (ISO
27509:2020)
Industries du pétrole et du gaz naturel - Raccordements à brides compactes avec bague
d'étanchéité IX (ISO 27509:2020)
Ta slovenski standard je istoveten z: EN ISO 27509:2020
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.

EN ISO 27509
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2020
EUROPÄISCHE NORM
ICS 23.040.60 Supersedes EN ISO 27509:2012
English Version
Petroleum and natural gas industries - Compact flanged
connections with IX seal ring (ISO 27509:2020)
Industries du pétrole et du gaz naturel - Erdöl- und Erdgasindustrie - Kompakte
Raccordements à brides compactes avec bague Flanschverbindungen mit IX Dichtungsring (ISO
d'étanchéité IX (ISO 27509:2020) 27509:2020)
This European Standard was approved by CEN on 12 February 2020.

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, 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 27509:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 27509:2020) 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 NEN.
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 2021, and conflicting national standards shall be
withdrawn at the latest by June 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 27509:2012.
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, 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 the
United Kingdom.
Endorsement notice
The text of ISO 27509:2020 has been approved by CEN as EN ISO 27509:2020 without any modification.

INTERNATIONAL ISO
STANDARD 27509
Second edition
2020-12
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 27509:2020(E)
©
ISO 2020
ISO 27509:2020(E)
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

ISO 27509:2020(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 2
4 Abbreviations and symbols . 2
4.1 Abbreviated terms . 2
4.2 Symbols . 3
5 Design . 5
5.1 General . 5
5.2 Design principles . 6
5.3 Assembly requirements . 8
5.4 Standard components . 8
5.5 Units of measurements . 9
5.6 Rounding . 9
5.7 Conformance with piping design codes . 9
5.8 Conformance with this document .10
6 Designation .10
6.1 Designation of flanges .10
6.2 Designation of seal rings .10
7 Materials .11
7.1 General .11
7.2 Flange materials.11
7.3 Bolting materials .11
7.4 Seal ring materials .12
8 Strength, pressure/temperature ratings and leak tightness .13
8.1 General .13
8.2 Pressure/temperature ratings .13
8.3 Pressure testing and leak tightness .14
9  Dimensions of flanges .14
9.1 General .14
9.2 Weld neck dimensions .15
9.3 Blind flange (BL) dimensions .23
9.4 Integral flange (IF) dimensions .26
9.5 Rigid interface dimensions .37
9.6 Dimensions of paddle blanks (PB) and paddle spacers (PS) .39
9.7 Handle and lifting lugs .41
9.8 Dimensions of orifice spacers (OS) .42
9.9 Dimensions of reducing threaded flanges .44
9.10 Auxiliary connections .45
9.11 Flange tolerances .45
9.12 Surface finish .47
10  Marking of flanges.48
10.1 Flanges other than integral flanges .48
10.2 Manufacturer's name or trademark .48
10.3 Nominal size .48
10.4 Pressure class designation .48
10.5 Pipe dimensions .48
10.6 Material identification .48
10.7 Identification of internally threaded flanges .49
ISO 27509:2020(E)
10.8 Material traceability .49
10.9 Marking examples .49
10.10 Stamping .49
11 Dimensions of seal rings .49
12 Manufacture, testing and inspection of IX seal rings .53
13 Coating and colour coding .53
14 Marking of seal rings .54
15 Quality management systems .54
16 Bolt dimensions and masses .54
Annex A (normative) Pressure temperature ratings and load capacity .55
Annex B (normative) Integral flange angle selection .59
Annex C (normative) Bolt dimensions and masses .70
Annex D (normative) Handling, installation, assembly and repair of flanges .77
Annex E (informative) Mass of flanges .90
Annex F (informative) Metric bolting .100
Annex G (informative) Additional information on bibliographical references .102
Bibliography .104
iv © ISO 2020 – All rights reserved

ISO 27509:2020(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document 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, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 12, Materials, equipment and offshore structures for petroleum,
petrochemical and natural gas industries, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 27509:2012), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 27509:2012/Cor.1:2013. The main changes
compared to the previous edition are as follows:
— Annexes B and D (Annex E in previous edition) have become normative annexes;
— more stringent quality requirements regarding manufacture of products and assembly instructions
have been introduced. These include
a) ultrasonic testing of products in accordance with new requirements in ASME VIII div. 2 (in
Clause 7),
b) requirements to material strength and machining strictly in accordance with given tolerances
for IX seal rings (in Clause 12),
c) new and better coating requirements for IX seal rings (in Clause 13 and Annex D),
d) excluding use of IX seal rings to assist alignment by transfer of significant shear load during
assembly (in Annex D),
e) more comprehensive and detailed guidelines on the evaluation of damages to products and the
repair of such damages (in Annex D),
f) more comprehensive requirements to qualification of bolt tensioning procedures (in Annex D),
and
ISO 27509:2020(E)
g) the elastoplastic deformation of flanges by first assembly has been better explained in 5.3
and in Annex D, in order to prevent unnecessary re-machining or rejection when flange bevel
angles have changed.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
vi © ISO 2020 – All rights reserved

ISO 27509:2020(E)
Introduction
This document, which is originally based on NORSOK L-005, has been developed to provide an
International Standard for compact flanged connections that constitutes an alternative to conventional
flanges as specified in ASME standards, European standards and other 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 conform with
the requirements of this document.
This document has been developed for use in process piping systems, which are designed in accordance
with codes for pressure piping, e.g. ASME B31.3. See 5.7 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 document.
The main body of this document 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, and
— requirements to designation and marking of finished products.
Annexes A, B, C and D cover the following topics:
— structural capacity equations for flange assemblies;
— how to apply the flanges to special geometries of valves and equipment nozzles;
— bolt dimensions and masses;
— installation and assembly instructions, and guidelines on how to repair damage and irregularities
on sealing surfaces.
Annexes E, F and G cover the following topics:
— masses of all standard components;
— suitable dimensions of alternative metric bolting;
— additional information on bibliographical references.
In this document, the following verbal forms are used:
— "shall" indicates a requirement;
— "should" indicates a recommendation;
— "may" indicates a permission;
— "can" indicates a possibility or a capability.
INTERNATIONAL STANDARD ISO 27509:2020(E)
Petroleum and natural gas industries — Compact flanged
connections with IX seal ring
1 Scope
This document 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 expressed in accordance with ASME B36.10M and ASME B36.19M.
This document 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 document is applicable within a temperature range from −196 °C to +250 °C.
This document is not applicable for external pressure.
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.
ISO 2768-1, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
ISO 4287, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Terms, definitions
and surface texture parameters
ISO 4288, Geometrical 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
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
EN 1779, Non-destructive testing — Leak testing — Criteria for method and technique selection
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 B31.3:2018, Process Piping
ISO 27509:2020(E)
ASTM B568, Standard Test Method for Measurement of Coating Thickness by X-Ray Spectrometry
ASTM B571, Standard Practice for Qualitative Adhesion Testing of Metallic Coatings
ASME VIII Div. 2: Boiler and Pressure Vessel Code — Alternative Rules
3  Terms and definitions
For the purposes of this document, the following terms and definitions 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
class
CL
pressure class in accordance with specific values
Note 1 to entry: The values shall be in accordance with ASME B16.5 and ASME B16.34
3.2
compact flanged connection
CFL
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
3.3
gasket
barrier to prevent the passage of fluids, but which does transmit all loads between flanges
3.4
purchaser
individual or organization that buys the pipe connection on behalf of the user and/or operator or for
its own use
3.5
seal ring
component providing a barrier to prevent the passage of fluids, transmitting no significant loads
between the flanges
3.6
supplier
individual or organization that takes the responsibility for the supply of the pipe connection
4 Abbreviations and symbols
4.1 Abbreviated terms
BL blind flange
DN nominal pipe diameter (expressed in millimetres)
ID internal diameter
IF integral flange (as part of some other equipment or component)
2 © ISO 2020 – All rights reserved

ISO 27509:2020(E)
IX special metallic seal ring applied in this document
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 (expressed in bar)
PS paddle spacer
PTFE polytetrafluoroethylene
RI rigid interface
RT reducing threaded flange
WN weld neck
4.2 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
A cross-sectional area of the neck/pipe calculated from t
C015 015
A cross-sectional area of a special flange neck geometry calculated from Formula (B.1)
Ceqv
A total cross-sectional area of bolting, based on root area
Cb
A hub diameter of reducing threaded flange
T
a maximum allowable alignment gap between mating flanges (see Figure D.4)
a bolt root area
Cb
B bore diameter, where the bore should not exceed the maximum listed bore in this document
B maximum listed bore diameter
max
B minimum bore diameter for which the face angles are valid
min
B minimum bore diameter for flange to be blinded
NOTE B is also the start diameter for blind and reducing threaded flange face angles.
B bolt circle diameter
CD
d bolt size (nominal bolt diameter)
B
d effective contact diameter of nut face (average between width of cross flats and diameter
n
of bolt hole)
ISO 27509:2020(E)
d average diameter of neck end = (A+B)/2
p
d effective (mean) contact diameter of bolting threads
t
D internal diameter of groove
A1
D outer diameter of groove
A3
D seal ring seal dimension (see Figure 13)
Gn
D inner recess diameter
W1
D outer recess diameter
W2
D outside diameter of flange
W3
D flange to neck fillet outer diameter
W4
e radial distance between B and d
CD p
E depth of groove
E depth of recess
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 required bolt preload
P
F resulting force from external tension force F and external bending moment M
R A A
f flange material yield strength at temperature
y
f bolt material yield strength at temperature
yb
H seal ring seal dimension (see Figure 13)
Gn
H thickness of PB, PS and OS
P1
H flange thickness
W3
H , H overall length
W5 T5
L bolt hole diameter
L , L , L bolt hole depths (see Figure 5 and Table 22)
1 2 3
l clear bolt length between engaged threads with the nuts
M applied bending moment
A
n number of bolts
P thread pitch of bolting
t
4 © ISO 2020 – All rights reserved

ISO 27509:2020(E)
p internal pressure in N/mm
R Radius
R radius (maximum value tabulated)
C
R neck to flange ring radius on integral flanges
V1
T torque applied to the bolt
t pipe wall thickness
t minimum neck thickness that can be used which is defined by the standard pipe outer
min
diameter, A, and maximum listed bore diameter, B .
max
t maximum neck thickness that can be used which is defined by A and the minimum
max max
listed bore diameter
t wall thickness giving the smallest possible face angle (0,15°)
t equivalent wall thickness calculated from A over H
eqv Ceqv W5
W Warping moment capacity of flange
f
X half major ellipse axis
Y half minor ellipse axis
α groove angle
A2
α flange face bevel angle
B1
α effective face angle/rear face bevel angle
B2
Δ fraction of the initially applied pre-stress lost in transfer of bolt load from tension tool
to the nut
ψ flange utilization ratio
μ coefficient of friction of nut bearing surface
n
μ coefficient of friction of bolting threads
t
5 Design
5.1 General
CFCs shall:
a) be designed for face-to-face make-up for transfer of the bolt loading through the flange faces;
b) be designed so that a static mode is maintained in the bolted joint up to 1,5 times the specified
pressure/temperature rating, see 8.2. 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;
c) be 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;
ISO 27509:2020(E)
d) be standardized to fit with commonly used standards by the valve industry [e.g. ASME B16.34,
ISO 14313 and EN 12516 (all parts)], and other valve standards which make reference to these
standards for pressure design;
e) conform with the applicable requirements in the piping or pressure vessel code agreed between
the supplier and the purchaser.
The weakest part of flanged connections in accordance with this document 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 7.3.
Supplier specific CFCs may refer to this document when additional requirements to the minimum
requirements specified in this document are agreed between purchaser and supplier. The intension is
to allow alternative and additional designs to the products in this document without compromising any
of the listed items a), b) and e) in this subclause as well as the requirements of 8.1 and 8.3.
5.2 Design principles
Figure 1 shows the design principles of compact flanges and its seal system in accordance with this
document.
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.
6 © ISO 2020 – All rights reserved

ISO 27509:2020(E)
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
The principle design of the flange face includes two independent seals, which are based on different
principles, a force controlled heel seal, and a displacement controlled seal provided by the seal ring.
The first seal is created by application of seal seating stress at the flange heel. However, an undamaged
flange heel might 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.
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.
ISO 27509:2020(E)
5.3 Assembly requirements
In order to conform with the design principles as described in 5.2, the flanged connections shall be
assembled to target bolt loads in accordance with Table 1. See Annex D for detailed guidelines on how
to assemble compact flanges.
Compact flange IX seal rings require sufficient flexibility to enable seal ring size entrance and removal.
The required spacing shall be considered during piping design and layout to ensure necessary flexibility
in the piping systems
The flange dimensions can be checked in accordance with the tolerances in Table 29. Note that the flange
gap at D defined by angle α can change after the first assembly. This is because the flange angles
W3 B2
are standardized and can be changed by plastic deformation to a more optimal value through shake
down to elastic conditions, by the first assembly. Such local plastic deformations have no influence on
further flange functionality and shall not be a reason for flange face re-machining request or flange
rejection. See Annex D for further guidelines on evaluating flange dimensions in the field.
Table 1 — Target residual preload for bolt materials used to assemble compact flanges to this
document
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 1 199
2 ½-8UN 1 503
2 ¾-8UN 1 667
3-8UN 2 004
3 ¼-8UN 2 373
3 ½-8UN 2 773
3 ¾-8UN 3 204
4-8UN 3 666
NOTE  See Table F.1 for equivalent using the metric system.
5.4 Standard components
The types of flanges covered by this document are given in Table 2.
8 © ISO 2020 – All rights reserved

ISO 27509:2020(E)
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 Integral flange as part of some other equipment Forging, forged bar (maximum DN 50) or casting
or component
RI Rigid interface as part of some other equipment Plate, forging or casting
or 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
5.5 Units of measurements
In this document, 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.
5.6 Rounding
Except as otherwise required by this document, 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.
5.7 Conformance with piping design codes
Although not listed as a component standard in ASME B31.3, all components contained in this
document fulfil the requirements for unlisted piping components in ASME B31.3. This is based on full
conformance:
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
document.
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 flanges according to this document was 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.
ISO 27509:2020(E)
5.8 Conformance with this document
The manufacturer shall be responsible for conforming with all of the applicable requirements of this
document. It shall be permissible for the purchaser to make any investigation necessary in order to be
assured of conformance by the manufacturer and to reject any material that does not conform.
6 Designation
6.1  Designation of flanges
The flanges shall be designated with the following infor
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