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SLOVENSKI STANDARD
01-julij-2022
Nadomešča:
SIST EN 14081-3:2012+A1:2018
Lesene konstrukcije - Po trdnosti razvrščen konstrukcijski les pravokotnega
prečnega prereza - 3. del: Strojno razvrščanje - Dodatne zahteve za tovarniško
kontrolo proizvodnje
Timber structures - Strength graded structural timber with rectangular cross section -
Part 3: Machine grading; additional requirements for factory production control
Holzbauwerke - Nach Festigkeit sortiertes Bauholz für tragende Zwecke mit
rechteckigem Querschnitt - Teil 3: Maschinelle Sortierung, zusätzliche Anforderungen an
die werkseigene Produktionskontrolle
Structures en bois - Bois de structure à section rectangulaire classé pour sa résistance -
Partie 3 : Classement mécanique ; exigences complémentaires relatives au contrôle de
la production en usine
Ta slovenski standard je istoveten z: EN 14081-3:2022
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
91.080.20 Lesene konstrukcije Timber structures
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 14081-3
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2022
EUROPÄISCHE NORM
ICS 79.040 Supersedes EN 14081-3:2012+A1:2018
English Version
Timber structures - Strength graded structural timber
with rectangular cross section - Part 3: Machine grading;
additional requirements for factory production control
Structures en bois - Bois de structure à section Holzbauwerke - Nach Festigkeit sortiertes Bauholz für
rectangulaire classé pour sa résistance - Partie 3 : tragende Zwecke mit rechteckigem Querschnitt - Teil
Classement mécanique ; exigences complémentaires 3: Maschinelle Sortierung, zusätzliche Anforderungen
relatives au contrôle de la production en usine an die werkseigene Produktionskontrolle
This European Standard was approved by CEN on 13 March 2022.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14081-3:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Requirements for the operation, calibration and maintenance of a grading machine . 6
5 Additional requirements for factory production control for machine control systems . 6
5.1 General . 6
5.2 Additional testing requirements . 6
6 Additional factory production control requirements for output control systems . 7
6.1 General . 7
6.2 Grading . 7
6.3 Sampling . 7
6.4 Destructive testing and calculation of characteristic values. 7
6.5 Batch verification . 8
6.6 Recording . 8
Annex A (normative) Requirements for using control planks . 9
A.1 General . 9
A.2 Requirements for selecting the control planks . 9
A.3 Requirements for the use of control planks for factory production control . 9
A.4 Requirements for the use of control planks during surveillance visits . 10
Bibliography . 11
European foreword
This document (EN 14081-3:2022) has been prepared by Technical Committee CEN/TC 124 “Timber
structures”, the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2022, and conflicting national standards shall
be withdrawn at the latest by October 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 14081-3:2012+A1:2018.
Compared to EN 14081-3:2012+A1:2018, the following modifications have been made:
— references to other parts of EN 14081 are undated;
— editorial changes to improve clarity of the text and to align terminology with the other parts of
EN 14081.
The other parts of the EN 14081 series are:
— EN 14081-1, Timber structures — Strength graded structural timber with rectangular cross section —
Part 1: General requirements;
— EN 14081-2, Timber structures — Strength graded structural timber with rectangular cross section —
Part 2: Machine grading; additional requirements for type testing.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Introduction
Machine grading is in common use in a number of countries. The countries use two basic systems,
referred to as ‘output control’ and ‘machine control’. Both systems require a visual override inspection to
cater for strength-reducing characteristics that are not automatically sensed by the machine.
The output control system is suitable for use where the grading machines are situated in sawmills grading
limited sizes, species and grades in repeated production runs of around one working shift or more. This
enables the system to be controlled by testing timber specimens from the daily output.
These tests together with statistical procedures are used to monitor and adjust the machine settings to
maintain the required strength properties for each strength class. With this system, it is permissible for
machine approval requirements to be less demanding and for machines of the same type to have
nonidentical performance.
The machine control system was developed in Europe. Because of the large number of sizes, species and
grades used, it was not possible to carry out quality-control tests on timber specimens drawn from
production. The system relies therefore on the machines being strictly assessed and controlled, and on
considerable research effort to derive the machines settings, which remain constant for all machines of
the same type.
The acceptability of grading machines and the derivation of settings rely on statistical procedures and
the results will therefore depend on the method used. For this reason, this document gives appropriate
statistical procedures.
The requirements in this document are based on machines in current use and on future types of machines
as far as these can be foreseen. It is recognized that additional clauses or standards might be required if
unforeseen developments take place.
1 Scope
This document specifies requirements additional to those given in EN 14081-1 for factory production
control of machine graded structural timber with rectangular cross-sections shaped by sawing, planing
or other methods, and having deviations from the target sizes corresponding to EN 336.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 384, Structural timber - Determination of characteristic values of mechanical properties and density
EN 408, Timber structures - Structural timber and glued laminated timber - Determination of some physical
and mechanical properties
EN 14081-1, Timber structures - Strength graded structural timber with rectangular cross section - Part 1:
General requirements
EN 14081-2, Timber structures - Strength graded structural timber with rectangular cross section - Part 2:
Machine grading; additional requirements for type testing
EN 14358, Timber structures - Calculation and verification of characteristic values
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 14081-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at
— IEC Electropedia: available at
3.1
production batch
one production run where the timber of one source, grade or grade combination, species or species
combination and size is graded using the same settings
4 Requirements for the operation, calibration and maintenance of a grading
machine
4.1 No modifications that are in conflict with the machine manufacturer’s specification shall be made
to the machine.
4.2 Access to all machine adjustments shall be limited to personnel authorized to operate or set up the
machine.
4.3 The strength grading machine shall be regularly calibrated in accordance with the manufacturer's
specification.
4.4 A strength grading machine shall only be fitted with spare parts equivalent to, or improving upon,
the performance of those fitted at the time the machine was assessed by initial type testing. If spare parts
are fitted that are not identical to those fitted at the time the machine was assessed by initial type testing,
the machine shall be reassessed to establish their effect on grading accuracy.
4.5 The details of routine service and maintenance to the strength-grading machine and ancillary
equipment shall be recorded together with the results of calibration checks.
5 Additional requirements for factory production control for machine control
systems
5.1 General
When grading structural timber in a machine control system, grading accuracy shall be monitored. A
grading machine’s dynamic performance shall be controlled by the use of control planks using the
procedures given in Annex A.
5.2 Additional testing requirements
This clause applies to bending strength classes with a characteristic bending strength level above
2 2
30 N/mm and for tension strength classes with a characteristic tension strength level above 21 N/mm .
These requirements only apply to softwoods. For hardwoods, specific requirements shall be established
within the factory production control.
During each working shift, two pieces of timber from each grade produced shall be randomly selected
and tested according to the strength class definition and EN 408. The fifth percentile value, determined
by ranking, of the last 100 strength values from 50 consecutive shifts shall meet t
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