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IS0
I N T ERN Ail ON A L O RG A N IZ AT1 O N FO R STA N DARD 12 AT1 ON
IS0 RECOMMENDATION
R 738
CONIFEROUS SAWN TIMBER
SIZES - TOLERANCES AND SHRINKAGE
1st EDITION
May 1968
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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 738, Coniferous sawn timber - Sizes - Tolerances and shrinkage,
was drawn up by Technical Committee ISO/TC 55, Sawn timber, the Secretariat of which is held by
the Komitet Standartov, Mer i Izmeritel'nyh Priborov pri Sovete Ministrov S.S.S.R. (GOST).
Work on this question by the Technical Committee began in 1956 and led, in 1963, to the
adoption of a Draft IS0 Recommendation.
In November 1965, this Draft IS0 Recommendation (No. 875) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies :
Ireland Spain
Australia
Italy Sweden
Canada
Japan Turkey
Czechoslovakia
Netherlands U.A.R.
Denmark
Poland U.S.S.R.
France
Portugal Yugoslavia
Hungary
Israel Romania
India South Africa, Rep. of
Five Member Bodies opposed the approval of the Draft :
Austria Germany
Belgium United Kingdom
Finland
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in May 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 738-1968 (E)
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IS0 Recommendation R 738 May 1968
CONIFEROUS SAWN TIMBER
SIZES - TOLERANCES AND SHRINKAGE
1. SCOPE
1.1 This IS0 Recommendation specifies permissible deviations, due to inaccuracies in sawing,
from nominal thickness, width and length of coniferous sawn timber.
For information, average values of shrinkage are given in Annex A and Annex B.
1.2 The IS0 Recommendation covers unplaned square-edged and unedged coniferous sawn timber
10 mm (0.3937’in) to 310 mm (12.2047 in) thick and/or wide.
2. DEVIATIONS AND SHRINKAGE
The nominal sizes of.sawn timber are established at 20 absolute moisture content.
2.1
The actual thickness and width of sawn timber with moisture content over 20 should be
larger, and those of sawn timber with moisture content below 20 may be smaller, than the
nominal sizes, by the corresponding shrinkage value.
Tables of average shrinkage are given for information in Annexes A and B.
NOTE. - Absolute moisture content is understood as moisture content related to oven-dry mass of timber
expressed in per cent.
2.2 The actual thicknesses of all kinds of sawn timber as well as widths of square-edged sawn timber
with parallel edges, in any cross section of each piece of sawn timber, may have permitted
deviations due to inaccuracy of sawing, from nominal sizes (corrected for shrinkage) not
exceeding
for thickness up to 29
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