National foreword

This British Standard is the UK implementation of ISO 3669:2020. It supersedes BS ISO 3669:2017, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee MCE/8/-/4, Vacuum technology.

A list of organizations represented on this committee can be obtained on request to its secretary.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 February 2020.

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: “l₇” has changed to “l₇ – Depth for pipe connection”;
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".

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.

It is noted, however, that the original ConFlat®1 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 Scope

This document specifies the dimensions of fixed or rotatable bolted knife-edge flanges used in vacuum systems for pressures ranging from atmospheric to as low as 10⁻¹¹ Pa.

2 Normative references

3 Terms and definitions

4 Symbols and abbreviated terms

5 Requirements

5.1 Materials

5.2 Dimensions

Bibliography

BS ISO 3669:2020

Vacuum technology. Dimensions of knife-edge flanges

Current, Under Review

Published:

30 Jun 2020