ISO 3669:2020

INTERNATIONAL ISO
STANDARD 3669
Third edition
2020-02
Corrected version
2020-05
Vacuum technology — Dimensions of
knife-edge flanges
Technique du vide — Dimensions des brides à guillotine
Reference number
ISO 3669:2020(E)
©
ISO 2020

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ISO 3669:2020(E)

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ii © ISO 2020 – All rights reserved

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ISO 3669:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 1
5 Requirements . 2
5.1 Materials . 2
5.1.1 Flange . 2
5.1.2 Bolt holes . 2
5.1.3 Grooves . . 2
5.1.4 Gasket . 2
5.2 Dimensions . 2
Bibliography . 7
© ISO 2020 – All rights reserved iii

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ISO 3669:2020(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 112, Vacuum technology.
This third edition cancels and replaces the second edition (ISO 3669:2017), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— the title has been updated;
— Clause 4 and Table 1: “l ” has changed to “l – Depth for pipe connection”;
7 7
— Reference [4] has been updated.
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.
This corrected version of ISO 3669:2020 incorporates the following correction:
— In Figure 2, the vertical dimension from the knife-edge to the surface of the flange has been corrected
from "0,98" to "0,65 ±0,05".
iv © ISO 2020 – All rights reserved

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ISO 3669:2020(E)

Introduction
This document is a minor revision of the second edition (ISO 3669:2017) and contains significant
technical changes from the first edition (ISO 3669:1986), which defined two series of “bakeable”
flanges:
— as a preferred series, the main dimensions of which ensure compatibility with already standardized
non-bakeable flanges (see ISO 1609);
— a secondary series corresponding to flanges in common use.
This document specifies only one series and is no longer dependent on the preferred number. Effectively,
the preferred series has been made obsolete, thereby promoting the secondary series to be the one and
only set of specified dimensions. Furthermore, several dimensions in what was formerly the secondary
series, have been modified to correspond to flanges in common use. Finally, detailed dimensions for the
knife-edge sealing profile have been incorporated.
1)
It is noted, however, that the original ConFlat® flange dimensions and tolerances, as developed by
Varian, were not available during the development stage of this specification. The intent of this document
is to ensure interchangeability of flanges. It is reasonable to accept that flanges manufactured to the
original Varian specifications are compatible with flanges manufactured according to this document,
even though they might not fall within all tolerances.
1) ConFlat® is the trademark of a product supplied by Varian, Inc. This information is given for the convenience of
users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products
may be used if they can be shown to lead to the same results.
© ISO 2020 – All rights reserved v

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INTERNATIONAL STANDARD ISO 3669:2020(E)
Vacuum technology — Dimensions of knife-edge flanges
1 Scope
This document specifies the dimensions of fixed or rotatable bolted knife-edge flanges used in vacuum
−11
systems for pressures ranging from atmospheric to as low as 10 Pa.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC mainta
...