BS ISO TR 11444-1996 Quality of sawn wood used for the construction of pallets《托盘结构用锯木质量》.pdf

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1、BRITISH STANDARD BS ISO TR 11444:1995 Implementation of ISO TR 11444:1995 Quality of sawn wood used for the construction of pallets ICS 55.180.20BSISOTR11444:1995 This British Standard, having been prepared under the directionof the Consumer Products and Services Sector Board, was published under th

2、eauthority of the Standards Board and comes into effect on 15 March 1996 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference PKW/3 Special announcement in BSINews September 1995 ISBN 0 580 25288 4 Committees responsible for this British Standard The prep

3、aration of this British Standard was entrusted to Technical Committee PKW/3, Distribution packaging, transport packaging and unit loads, upon which the following bodies were represented: British Adhesives and Sealants Association British Apparel and Textile Confederation British Carton Association B

4、ritish Fibreboard Packaging Association British Glass Manufacturers Confederation British Industrial Truck Association British Plastics Federation British Retail Consortium British Rubber Manufacturers Association Ltd. British Tensional Strapping Association Ltd. British Timber Merchants Association

5、 British Wood Preserving and Damp-proofing Association Chamber of Shipping Chemical Industries Association China Clay Association Cranfield Logistics Department of Transport Engineering Equipment and Materials Users Association Federation of the Electronics Industry Flexible IBC Association Food and

6、 Drink Federation Independent Pallet Repair Committee Institute of Grocery Distribution Metal Packaging Manufacturers Association Ministry of Defence National Association of Pallet Distributors Power Fastenings Association Pira International Road Haulage Association Ltd. Society of Motor Manufacture

7、rs and Traders Ltd. Storage Equipment Manufacturers Association Timber Packaging and Pallet Confederation Timber Research and Development Association United Kingdom Softwood Sawmillers Association Amendments issued since publication Amd. No. Date CommentsBSISOTR11444:1995 BSI 10-1999 i Contents Page

8、 Committees responsible Inside front cover National foreword ii Foreword iii Text of ISO TR 11444 1BSISOTR11444:1995 ii BSI 10-1999 National foreword This British Standard reproduces verbatim ISO TR11444:1995 and implements it as the UK national standard. This British Standard is published under the

9、 direction of the Consumer Products and Services Sector Board whose Technical Committee PKW/3 has the responsibility to: aid enquirers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed;

10、monitor related international and European developments and promulgate them in the UK. NOTEInternational and European Standards, as well as overseas standards, are available from Customer Services, BSI, 389 Chiswick High Road, London W44AL. A British Standard does not purport to include all the nece

11、ssary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theIS

12、O TR title page, pages ii to iv, pages1 to 6, an inside back cover and abackcover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.ISO/TR11444:1995(E) ii BSI 10-1999 Contents Page Fo

13、reword iii Introduction 1 1 Scope 1 2 Moisture content 1 3 Deterioration and decay 2 4 Stains, moulds and weathering 2 5 Checks, splits and shakes 3 6 Bark and wane 3 7 Knots 3 8 Slope of grain (cross grain, diagonal grain) 4 9 Rate of growth 5 10 Density 5 11 Sawn-surface finish and deck-surface fr

14、iction requirements 5 12 Strength and stiffness 6 13 Nail withdrawal and shear resistance 6 Annex A (informative) Bibliography Inside back cover Figure 1 Pallet components showing end shakes and splits 3 Figure 2 Knot in a pallet board 4 Figure 3 Grain slope in pallet stringer 4 Figure 4 Measurement

15、 of slope of grain 5 Table 1 Examples of strength properties of softwoods 2ISO/TR11444:1995(E) BSI 10-1999 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies).The work of preparing International Standards is

16、 normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part

17、 in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The main task of technical committees is to prepare International Standards, but in exceptional circumstances a technical committee may propose the publ

18、ication of a Technical Report of one of the following types: type1, when the required support cannot be obtained for the publication of an International Standard, despite repeated efforts; type2, when the subject is still under technical development or where for any other reason there is the future

19、but not immediate possibility of an agreement on an International Standard; type3, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example). Technical Reports of types1 and2 are subject to r

20、eview within three years of publication, to decide whether they can be transformed into International Standards. Technical Reports of type3 do not necessarily have to be reviewed until the data they provide are considered to be no longer valid or useful. ISO/TR11444, which is a Technical Report of t

21、ype2, was prepared by Technical Committee ISO/TC51, Pallets for unit load method of materials handling. This document is being issued in the type2 Technical Report series of publications (according to subclause G.4.2.2 of part1 of the ISO/IEC Directives,1992) as a “prospective standard for provision

22、al application” in the field of sawn wood used for the construction of pallets because there is an urgent need for guidance on how standards in this field should be used to meet an identified need. This document is not to be regarded as an “International Standard”. It is proposed for provisional app

23、lication so that information and experience of its use in practice may be gathered. Comments on the content of this document should be sent to the ISO Central Secretariat. A review of this type2 Technical Report will be carried out not later than two years after its publication with the options of:

24、extension for another two years; conversion into an International Standard; or withdrawal. Annex A of this Technical Report is for information only.iv blankISO/TR11444:1995(E) BSI 10-1999 1 Introduction Components of wooden pallets typically exhibit major differences in physical and mechanical prope

25、rties between pieces of identical shape, size and species. These differences are caused by natural variations in the growth of a living tree, the anisotropic characteristics of wood, and the manufacturing practices used in the conversion of wood into industrial and consumer products. Each of these d

26、ifferences significantly alters the physical, mechanical and aesthetic properties of wood and wood by products. The properties of wooden pallets of like design will vary significantly if the size, frequency, location and type of variation are not controlled. For example, a large knot located above t

27、he notch cut into a wooden stringer/bearer can cause potentially catastrophic failure of a pallet in bending, even when the pallet is carrying well below its rated load. Some of the variations affecting the physical and mechanical properties of wood are a direct result of infestation or plant diseas

28、es such as American or European chestnut blight and Dutch elm disease. The unrestricted intercontinental distribution of pallets containing infested wood can and has resulted in the devastation of unresistant timber species. Reasons for recognizing natural variations in wood in order to control the

29、quality of sawn wood in pallets include: assembly of the most cost-effective pallet; selection of a superior pallet at minimal cost; determination of the life cycle cost between pallets of differing grades and quality; prediction of the strength of pallets of like design; prevention of potentially d

30、angerous failure; control of the spread of plant disease. The Technical Committee ISO/TC51 has therefore decided to publish these guidelines, prepared by Working Group WG5, in the form of a Technical Report. In view of the way in which current ISO test methods and performance requirements for pallet

31、s are specified and the general move by national and international standardization bodies away from specifying strict material quality standards, this Technical Report does not provide grading rules intended to ensure a minimum strength quality of wood. It is essential that it remains possible to me

32、et the performance requirements specified in ISO/TR10233 using any hardwood or softwood, from any country in the world, by modifying the wood or fastenings content to achieve the required performance. The guidelines, although related primarily to wooden pallets, may also be of value in relation to t

33、he construction of wooden packaging for industrial or agricultural purposes. A list of International Standards related to this Technical Report is given inAnnex A. 1 Scope This Technical Report gives information on the faults and features which may affect sawn wood used for the construction of palle

34、ts, and provides guidance on their effects in relation to the physical and mechanical properties of both components and complete wooden pallets. It is strongly recommended that these guidelines be followed when wooden pallets are constructed for testing in accordance with ISO8611, while their use in

35、 pallet manufacture should provide a more consistent level of performance. NOTE 1In view of the different timber species used for pallet construction in various parts of the world, it may be appropriate for member bodies adopting this Technical Report to add information about the characteristics of

36、species used for the construction of pallets in their respective countries. 2 Moisture content 2.1 A proportion of the water in wet wood (around25%) is chemically bound in varying degrees to the wood fibres. Living trees and freshly felled sawn timber can contain even more water than this (up to200%

37、 of free water, with even more in certain species 1) ). 1) Moisture content can be above100% because of the method of definition where the mass of water is expressed as a percentage of the oven-dry mass of the wood.ISO/TR11444:1995(E) 2 BSI 10-1999 2.2 There are two methods of measuring moisture con

38、tent in common use. The most common method, a rapid test using an electrical moisture meter, is an essentially non-destructive test which is based upon the principle that the electrical resistance of wood varies with its moisture content. Meters are commonly marked to indicate a range between6% and5

39、0% moisture content, but their accurate range is normally from9% to25%. A skilled user can obtain results between these limits within 2% of the true moisture content. They are particularly appropriate for pallet work where extreme accuracy is not needed. The other method used takes at least several

40、hours to achieve a reading and is destructive, in that it involves taking the whole piece of wood (or a tiny rectangular cut sample), weighing it to determine the mass of wood plus the water it contains, drying it to obtain the dry mass and calculating the moisture content as follows: NOTE 2Wood in

41、which the mass of water is equal to the mass of dry wood has a moisture content of100%. Known as the “oven-drying method”, this is the more precise method, but is only necessary for accurate testing or for research work. 2.3 Before wood is stored or used to construct pallets, it is usually necessary

42、 to remove a portion of the water it contains. The reason for drying prior to storage is that wood of many species will decay if kept at a high moisture content for long periods and, even in the short term, susceptible species will suffer from mould and staining (see clause4). Examples of this are t

43、he blue stain that particularly affects pine species, although spruces and others are also susceptible. Below about20% moisture content, a level known as the decay safety line (timber line), wood is generally safe from such discoloration or damage. 2.4 Wet pallets are less stiff (i.e. bend more unde

44、r a given load) and less strong (i.e. have a lower breaking strength and a lower maximum working load) than dry pallets. Allowance needs to be made for this both during the test and in actual usage, since their performance when under load can vary enormously with a change in moisture. The change can

45、 be typically, for Douglas fir, a reduction of19% in terms of strength comparing green timber with air-dry, or a23% change for European redwood (seeTable 1 for examples). Table 1 Examples of strength properties of softwoods 3 Deterioration and decay This Technical Report gives only basic guidance on

46、 this complex and extensive subject. Many types of timber decay can be spread by insects and worms and, in view of the fact that it is difficult for pallet manufacturers to distinguish between the two, it is advisable that none at all should be present. Sporophores, surface mycelium, brash and punky

47、 wood can have major weakening effects and should be avoided in any pallet member. Decay cannot occur in wood having a moisture content less than15% (based on oven-dry weight) and decay of consequence will not usually occur in wood having a moisture content less than20%. To prevent such deterioratio

48、n, pallets should be stored in an environment that ensures that a moisture content of20% is not exceeded. Decay will have a strength-reducing factor in relation to the volume of wood affected. Mineral streaks and stains do not affect the structural strength of pallets and are acceptable. 4 Stains, m

49、oulds and weathering 4.1 Stain is the term used to describe a discoloration, frequently deep in the wood substance, caused by chemical reactions or fungi, whereas mould is the surface discoloration caused by staining fungi which can sometimes be brushed off and is easily removed by planing. NOTE 3Blue stain is often, but not always, a mould. It also frequently penetrates the sapwood, which is why this Technical Report does not define stain as chemical (mechanical) discoloration and mould as fungal discoloration even though this is true for