ISO/TS 3669-2:2007

TECHNICAL ISO/TS
SPECIFICATION 3669-2
First edition
2007-09-01

Vacuum technology — Bakable flanges —
Part 2:
Dimensions of knife-edge flanges
Technique du vide — Brides étuvables —
Partie 2: Dimensions des brides à guillotine




Reference number
ISO/TS 3669-2:2007(E)
©
ISO 2007

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ISO/TS 3669-2:2007(E)
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ii © ISO 2007 – All rights reserved

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ISO/TS 3669-2:2007(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
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In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of normative document:
⎯ an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
⎯ an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
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ISO/TS 3669-2 was prepared by Technical Committee ISO/TC 112, Vacuum technology.
ISO 3669 consists of the following parts, under the general title Vacuum technology — Bakable flanges:
⎯ Dimensions
⎯ Part 2: Dimensions of knife-edge flanges [Technical Specification]
© ISO 2007 – All rights reserved iii

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ISO/TS 3669-2:2007(E)
Introduction
This Technical Specification contains significant technical changes from ISO 3669:1986, which defined two
series of bakable flanges:
⎯ a preferred series, the main dimensions of which ensure compatibility with already standardized non-
bakable flanges (see ISO 1609);
⎯ a secondary series corresponding to flanges in common use.
This part of ISO 3669 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 into being
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.

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TECHNICAL SPECIFICATION ISO/TS 3669-2:2007(E)

Vacuum technology — Bakable flanges —
Part 2:
Dimensions of knife-edge flanges
1 Scope
This part of ISO 3669 specifies the dimensions of fixed or rotatable bolted knife-edge style bakable flanges
–13
used in vacuum systems for pressures ranging from atmospheric to as low as 10 Pa.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
knife-edge style flange
metal sealed flange used for high and ultra-high vacuum service
NOTE 1 The sandwiching of one metal gasket between two knife-edge flanges and securely bolting these together
makes a vacuum-tight joint. The seal is made when the conical knife edge profile of the flange cuts into the flat surface of
a metal gasket.
1)
NOTE 2 Originally developed as Conflat flanges. The widespread and continued use of knife-edge flanges has made
these a de facto international standard, codified by this Technical Specification.
2.2
nominal bore
value intended to both identify the flange and specify the largest practical size of tubing that can be
accommodated by the flange
NOTE See Table 1, in which the convention of identifying original flanges by the outside diameter of the flange
(historically in inches) has been maintained.
2.3
leak check groove
groove machined into the seal side of the flange to facilitate the free passage of search gas from the outer
perimeter of the flange to the seal zone near the metal gasket

1) Conflat® is the trade name of a product supplied by Varian Corporation. This information is given for the convenience
of users of this Technical Specification and does not constitute an endorsement by ISO of the product named. Equivalent
products may b
...