1、BRITISH STANDARD BS 1990-1: 1984 (Reprinted, incorporating Amendment No. 1) Wood poles for overhead power and telecommunication lines Part 1: Specification for softwood poles UDC 621.315.668.1:674.032BS1990-1:1984 This British Standard, having been prepared under the directionof the Timber Standards
2、Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 28 September1984 BSI 07-1999 First published (imperial units) July 1953 First published (metric units) March 1971 First revision September 1984 The following BSI references relate to the work on this standard: Co
3、mmittee reference TIB/20 Draft for comment 81/15497 DC ISBN 0 580 14021 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Timber Standards Committee (TIB/-) to Technical Committee TIB/20 upon which the following bodies were represented:
4、Association of Consulting Engineers British Tar Industry Association British Telecommunications British Timber Merchants Association British Wood Preserving Association Department of Energy (Electricity Division) Department of the Environment (Building Research Establishment, Princes Risborough Labo
5、ratory) Electricity Supply Industry Forestry Commission Home Timber Merchants Association of Scotland Timber Growers UK Ltd. Timber Research and Development Association Timber Trade Federation Amendments issued since publication Amd. No. Date of issue Comments 5043 April 1986 Indicated by a sideline
6、 in the marginBS1990-1:1984 BSI 07-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Timbers 1 4 Felling 1 5 Sizes and permitted tolerances 1 6 Limiting characteristics 1 7 Stacking and preparation of poles at depots 2 8 Moisture content 2 9 Prese
7、rvation 2 10 Marking 3 Appendix A Design data for the strength of poles, unstayed and stayed 5 Appendix B Determination of moisture content by the oven test method 9 Appendix C Determination of the extent of preservative penetration 9 Appendix D Determination of strength characteristics of poles 9 F
8、igure 1 Typical layout of markings 4 Figure 2 Testing position of a pole 11 Table 1 Preferred sizes of poles 6 Table 2 Ultimate loads for unstayed poles of redwood 7 Table 3 Ultimate loads for stayed poles (struts) of redwood 8 Table 4 Modification factors for the loads given in Table 2 and Table 3
9、8 Publications referred to Inside back coverBS1990-1:1984 ii BSI 07-1999 Foreword This British Standard, having been prepared under the direction of the Timber Standards Committee, supersedes BS1990:1971which is withdrawn. The revision is being undertaken in two Parts; Part1covering softwood poles a
10、nd Part 2 1)which will cover hardwoods. The first standard for wood poles for overhead lines was published in1953. A metric version of the1953edition was prepared and published in1971superseding the imperial version in1974. The difference between this edition and the1971edition is that this standard
11、 extends the range of timber species for which data are available, specifies water-borne preservative treatments in addition to pressure creosoting and gives a typical layout of markings. This standard is based primarily upon the predominant species in use, namely redwood or Scots pine (Pinus sylves
12、tris) from Northern Europe including the UnitedKingdom. The growth characteristics of timbers and their freedom from decay and other defects are of importance in the determination of the mechanical strength of poles for assessing the safe loads in service. The calculated average breaking loads of re
13、dwood or Scots pine poles both unstayed and stayed are included in Appendix A. Appendix B describes a method of determining the moisture content of poles and Appendix C describes a method for determining the extent of preservative penetration. Appendix D describes a method for establishing the stren
14、gth characteristics for the species listed in this standard. The attention of pole users is drawn to the difficulty of defining and working to precise requirements on all aspects of a natural product such as timber. Some properties have of necessity been specified in general terms only. It is theref
15、ore recommended that the acceptance of poles, and the supervision of seasoning tests and of preservation processes should be assigned only to qualified and experienced inspectors. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards ar
16、e 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, pages1 to 14, an inside back cover and a back cover. This standard
17、 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. 1) In course of preparation.BS1990-1:1984 BSI 07-1999 1 1 Scope This British Standard specifies requirements for solid softwood poles for power an
18、d telecommunication lines (seeclause3). NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard the definitions given in BS565, BS 4261and BS6100-4.1 apply. 3 Timbers Poles shall be made from the fol
19、lowing species. NOTEThe preferred dressed sizes of poles should be as given inTable 1. Poles of redwood should support the loads given inTable 2 and Table 3 derived from the calculations in accordance withAppendix A. Poles of the species listed under item b) should support the loads given inTable 2
20、and Table 3 modified by the appropriate factors given inTable 4. 4 Felling Trees other than spruce, grown in Northern Europe, shall be felled between1 November and the following31 March. They shall be sawn off as close to the ground as possible and no timber shall be removed, trimmed or cut from the
21、 butt end so as to reduce its natural size. The ends shall be sawn to give a flat section and branches shall be dressed down flush with the trunk. Bark shall be removed as soon as practicable after felling and the poles shall then either be stacked in open formation clear of the ground, or stored in
22、 water that is free from marine borer activity. 5 Sizes and permitted tolerances NOTEThis standard is applicable to all sizes of pole, however, it will generally be more economic to specify the preferred dressed sizes given in Table 1. 5.1 Measurement Many nominally round poles have a natural ellipt
23、ical cross section; the cross section measurements of such poles shall be of the minor axes. 5.2 Tolerance on length The tolerance on length shall be1% of the specified length. 6 Limiting characteristics NOTESome limiting characteristics may be eliminated by cross cutting and/or dressing to produce
24、an acceptable pole. 6.1 Straightness Sweep or crook shall be permitted to the extent that a straight line from the centre of the top to the centre of the pole1.5m from the butt remains within the pole. 6.2 Knots At any cross section along the length of a pole no knot with a diameter, measured at rig
25、ht angles to the length of the pole, greater than one-fifth of the circumference shall be permitted, and the sum of knot diameters at the cross section shall not exceed one-quarter of the circumference 2) . 6.3 Fissures Cracks across poles shall not be permitted. NOTESeasoning checks and shakes alon
26、g the grain are expected and are not recognized as defects. 6.4 Ring and star shakes The tip shall be free from ring or star shakes but one complete ring or one star shake is acceptable at the butt provided that no part extends to within 50mm from the periphery. 6.5 Slope of grain Spiral grain shall
27、 not exceed a slope of1in6. 6.6 Inbarks Inbarks shall be permitted with limitations on their length, width and depth. Maxima are given for each dimension, but when assessing inbarks, the maxima shall only be permitted for one measurement, with half the value given for the other two. a) Redwood or Sc
28、ots pine a (Pinus sylvestris) b) Corsican pine (Pinus nigra) Douglas fir (Pseudotsuga menziesii) Dunkeld (hybrid) larch (Larix eurolepis) European larch (Larix decidua) European (Norway) spruce (Picea abies) Japanese larch (Larix kaempferi) Lodgepole pine (Pinus contorta) Sitka spruce (Picea sitchen
29、sis) Western red cedar (Thuja plicata) a Hereinafter referred to as redwood. 2) The limitations on knots are based on past practice and satisfactory performance. Suitable test results relating knot size to performance are not available.BS1990-1:1984 2 BSI 07-1999 The maximum dimensions of inbarks sh
30、all be as follows. 6.7 Insect holes Pinholes and boreholes shall be permitted, provided there is no active infestation and the strength of the pole is not affected by the degree of damage. 6.8 Decay Rot or punks shall not be permitted. 6.9 Abnormal defects Other defects, such as mechanical damage, s
31、hall be permitted provided that their effect on the structural strength of the pole is likely to be no greater than the effect of any other limiting characteristic. 6.10 Sapstain Blue stain in the sapwood of softwoods shall not be considered a defect. 7 Stacking and preparation of poles at depots Al
32、l poles other than spruce shall be stacked in open formation, before and after dressing, on suitable skids so that the lowest timber of each stack is at least250mm above the ground. Sufficient dunnage or cross timbers shall be used to distribute the total mass without imposing undue strain on the po
33、les at the lower layers. The surface of the seasoning ground under and around the stacks shall be well drained and kept free from bark, shavings, grass and weeds. All poles shall be machine dressed to remove the cambium layer before preservation. All drilling, notching and cutting of poles shall be
34、completed before preservation. 8 Moisture content Preservation of species other than spruce shall not take place until the average moisture content of each batch of poles is reduced to not more than 28%. No individual pole in the batch shall have a moisture content greater than30%. The moisture cont
35、ent of the poles shall be determined prior to treatment by the oven test method described inAppendix B or by the use of moisture meters. When using the latter, any measurements over25% shall be confirmed by the oven test method. Poles for preservation shall be protected against heavy and continuous
36、rain. NOTESeasoning is deemed to commence at the time of felling, and under average weather conditions light, medium and stout poles should be seasoned for at least6,9 and12months respectively, before preservation. 9 Preservation NOTELong life is a prerequisite for poles and preservative treatment i
37、s essential. It is recommended that poles complying with this standard have an average service life of40years. 9.1 General The following species shall be pressure impregnated with creosote in accordance with BS913or with a copper/chrome/arsenic mixture in accordance with BS4072. When pressure impreg
38、nating in accordance with BS913, the coal tar creosote used shall comply with type2of BS144and the average net retention of preservative in a charge shall be not less than115kg/m 3 . When pressure impregnating in accordance with BS4072, the copper/chromate/arsenic (CCA) mixture shall have a solution
39、 strength not less than3% m/V. NOTE 1When creosoting is carried out using the Rueping (empty cell) process the gross absorption, to obtain full sapwood penetration, is likely to be double the net retention. However, as the depth of sapwood varies from pole to pole and between species, this level of
40、gross absorption is included for guidance only. NOTE 2The average net retention figures given in BS913and BS4072are average values for a whole charge and do not apply to individual poles. Owing to natural variations in the permeability of wood it has to be accepted that the net retention of individu
41、al poles may cover a considerable range on either side of any average value specified for the charge. Initial, gross and net absorptions may also vary from that specified due to the variation in the depth of sapwood present and the species being treated. As the following species cannot be treated wi
42、th preservative in the normal way by the procedures described in BS913and BS4072, they shall be preserved using a suitable modification of one of the procedures described in those standards, to meet the requirements for full sapwood penetration and net retention. Length: 4 diameter of pole Width: 0.
43、5 diameter of pole Depth: 12 mm Redwood Corsican pine Douglas fir Dunkeld larch European larch Japenese larch Lodgepole pine Western red cedar European (Norway) spruce Sitka spruceBS1990-1:1984 BSI 07-1999 3 9.2 Preparation of poles for treatment Preservative treatment shall not take place until all
44、 dressing, notching, pre-cutting and boring has been completed. NOTEFabricated poles ready for treatment are to be protected against heavy and continuous rain (seeclause8). 9.3 Extent of penetration of preservative When examined in accordance withAppendix C, all sapwood shall be completely penetrate
45、d with preservative. 10 Marking 10.1 General Each pole shall have a gouge or brand mark at least50mm long,5mm wide and 3mm deep placed3m from the butt and shall be marked with the information specified in10.2 and10.3 in characters not less than25mm high and gouged or branded5mm wide and3mm in depth.
46、 Spacings between codes shall be between20mm and30mm (seeFigure 1). 10.2 Above the gouge mark Each pole shall be marked with the following information above the gouge mark: a) length of pole (in m); b) class of pole, i.e.L (light), M (medium) or S (stout) or, alternatively, the diameter (in mm) at1.
47、5m from the butt. NOTEThe ownership mark may also be marked if required. 10.3 Below the gouge mark Each pole shall be marked with the following information below the gouge mark: a) species code, i.e.: b) country of origin 3) , i.e.: c) last two digits of year of preservation. NOTEThe depot supplying
48、 the pole and the name or mark of the preserver may also be marked. Poles preserved with creosote shall carry no other distinguishing mark. Other forms of preservation shall be denoted by appropriate letters. 10.4 The butt end Each pole shall have the following information impressed on the butt end
49、grain: a) length of pole (in m); b) class of pole, i.e.L (light), M (medium) or S (stout) or, alternatively, the diameter (in mm) at1.5m from the butt. CF Corsican pine DF Douglas fir LP Lodgepole pine LX Larch, Dunkeld Larch, European Larch, Japanese NS Norway spruce SP Scots pine or Redwood SS Sitka spruce WC Western red cedar GB United Kingdom CA Canada FI Finland NO Norway SE Sweden 3) For abbreviations of other countries, seeBS5374. BS1990-1:1984 4 BSI 07-1999 All characters are to have a minimum height of 25 mm and gouged or branded 5 mm wide a
