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IS0
I N T ERN AT I O N A L ORGANIZATION FOR STAND A RD IZATION
IS0 RECOMMENDATION
R 388
IS0 METRIC SERIES FOR BASIC THICKNESSES OF SHEET
AND DIAMETERS OF WIRE
1st EDITION
October 1964
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 388, International Metric Series ,for Basic Thicknesses of
Sheet and Diameters of M’ire. was drawn up by Technical Committee ISOjTC 62, Sheet and
Wire Gauqes i Designation of Diatneters and Thicknesses). the Secretariat of which is held by the
Standards Association of Australia (SAA).
Work on thi5 question b> the Technical Committee began in 1953 and led, in 1959, to the
adoption of a Draft IS0 Recommendation.
In No\ember 1959. this Draft IS0 Recommendation (No. 324) was circulated to all the
It was approved, subject to a few modifications of an edi-
IS0 Member Bodies for enquiry.
torial nature, by the following Member Bodies:
Australia Hungary Portugal
Burma India Romania
Italy Sweden
Chile
Czechmlol akia Japan United Kingdom
Finland Netherlands U.S.S.R.
New Zealand Yugoslavia
France
Norway
German)
Greece Poland
One Member Body opposed the approval of the Draft:
U.S.A.
IS0 Recommendation was then submitted by correspondence to the IS0 Council,
The Draft
\vhich decided. in October 1964, to accept it as an IS0 RECOMMENDATION.
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FOREWORD
The designation of thicknesses of sheet and diameters of wire by arbitrary gauge numbers
has long been recognised as presenting difficulties because of the multiplicity of gauge systems
currently in use, and because the significance of gauge numbers may, in fact, vary from industry
to industry and from country to country.
The purpose of this IS0 Recommendation is to provide a basic set of sizes (in millimetres)
for thicknesses of sheet and for diameters of wire, to replace existing gauge systems. The nominal
size of a sheet thickness or a wire diameter is the basic size as given in the tabulation.
It is contemplated that, where a specification for sheet or wire lays down standard thicknesses
or diameters, the sizes given should be a selection from the series of basic sizes given in this
IS0 Recommendation, such selection taking account of the thicknesses or diameters appropriate
to the product in question and of the extent of size differentiation appropriate to its manufacture
and application. Attention is drawn to the note to the Table of Basic Sizes, recommending that,
in the selection of sizes, preference should be given to the R 10, R 20 and R 40 series, in that
order. In particular, the use of the R 40 series is to be avoided, except where application requires
fine differentiation of sizes.
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ISO/R 3â8 - 1S4 (E)
IS0 Recommendation R 388 Octo ber 1964
IS0 METRIC SERIES FOR BASIC THICKNESSES
OF SHEET AND DIAMETERS OF WIRE
The IS0 metric series for the basic thicknesses of sheet and diameters of wire is estab-
lished on the series of preferred numbers set out in 1SO Recommendation R 3-Preferred
nuinhers. Series of preferred numbers. See Table, pages 6 and 7.
The range of sizes is from 0.020 to 25 mm.
In selecting sizes. prefxence should be given to sizes in the R IO, R 20 and R 40 series, in
that order.
The method of designating the thickness of sheet or diameter of wire is to be by stating
the basic size in millimetres followed. if desired. by the letter U to indicate that this size
belongs to the IS0 metric series.
NOTE. - The equivalent inch
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