ISO INTERNATIONAL STANDARD 13912 Second edition 2017-11 Structural timber Machine strength grading Basic principles Bois de structure - Classement par machine selon la résistance - Principes de base Reference number IS0 13912:2017(E) @ IS0 2017 IS0 13912:2017(E) COPYRIGHT PROTECTED DOCUMENT @ IS0 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either Iso at the address below or ISo's member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org ii @ IS0 2017 - All rights reserved IS0 13912:2017(E) Contents Page Foreword .iv Introduction. .V 1 Scope. .1 2 Normative references .1 3 Terms and definitions 1 4 Symbols and abbreviated terms 5 General. 1 5.1 Machine strength-graded timber 5.2 Machine strength-grading operations 5.3 Machine strength-grading quality procedures 2 5.3.1 Machine-controlled system. 2 5.3.2 Output-controlled system. .2 6 Resource and sawn timber input requirements .3 6.1 General .3 6.2 Input requirements. 4 6.2.1 Resource. 4 6.2.2 Sawn timber .4 6.3 Control of inputs 4 6.4 Reprocessing of previously graded material .4 7 Machine strength-grading requirements 4 7.1 Machine checking requirements 4 7.2 Machine acceptance criteria. 4 7.3 Machine strength-grading requirements 5 7.4 Visual grading requirements 5 7.4.1 General. 5 7.4.2 Automated visual grading 5 8 Machine strength-graded timber structural properties .5 8.1 General 5 8.2 Initial evaluation .5 8.3 Daily evaluation. .6 9 Product identification .6 10 Documentation. .6 Annex A (informative) Example of a machine strength-grading timber standard .7 Annex B (informative) Use of the CUsUM procedure for daily evaluation. .20 Annex C (informative) Strength-grading machine acceptance considerations. ..24 Annex D (informative) Training, supervision and oversight of grading .26 @ IS0 2017 - All rights reserved iii