ISO 738:2015 pdf free
ISO 738:2015 pdf free.Coniferous sawn timber一Sizes一Permissible deviations and shrinkage
ISO 738 specifies permissible deviations, due to inaccuracies in sawing, from nominal thicknesses, widths and lengths, for coniferous sawn timber.
It also gives, for information, average values for shrinkage for some wood species.
It is applicable to unplanned square-edged and unedged coniferous sawn timber having thicknesses or widths in the range10 mm to 310 mm.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 24294, Timber一Round and sawn timber一Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 24294 apply.
4 Permissible deviations and shrinkage
The nominal sizes of coniferous sawn timber are established at an absolute moisture content of 20 %.
NOTE The absolute moisture content is the moisture content related to the oven-dry mass of the timber,expressed as a percentage.
The actual thickness and width of sawn timber having moisture contents greater than 20 % may be larger than, and those of sawn timber having moisture contents less than 20 % may be smaller than, the nominal sizes, by the corresponding value for shrinkage.
Average values for shrinkage are given, for information, in Annexes A and B.The actual thicknesses of all kinds of coniferous sawn timber, and the widths of square-edged sawn timber with parallel edges, in any cross-section of each piece of sawn timber, may deviate, due to inaccuracy in sawing, from the nominal sizes corrected for shrinkage by not more than
a) for thicknesses and widths in the range up to and including 30 mm to 105 mm: ±2 mm;
b) for thicknesses and widths greater than 105 mm: ±3 mm.
If 20 pieces of the same size are taken at random from a lot of sawn timber, the average actual thickness (irrespective of the kind of sawn timber) and the average actual width of square edged sawn timber with parallel edges shall not be less than the nominal sizes, corrected for shrinkage.
The permissible deviations of actual lengths of sawn timber from the nominal length, due to inaccuracy in sawing, shall be +50 mm, and -25 mm.ISO 738 pdf download.
