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 2020
© ISO 2020
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Published in Switzerland
ii © ISO 2020 – All rights reserved

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
Foreword
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electrotechnical standardization.
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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).
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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

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.
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
...