ISO 15206:2010
(Main)Timber poles — Basic requirements and test methods
Timber poles — Basic requirements and test methods
ISO 15206:2010 specifies the requirements for grading, test methods, determination of characteristic values, methods of specifying durability and sizes of single poles manufactured from solid timber for telecommunications and electrical distribution purposes, either preservative treated or untreated, under cantilever or compression loading. It specifies the methods of measuring the sizes of solid wood poles for overhead transmission and telecommunication lines and permissible deviations that are taken into account for the acceptance of the poles; the requirements for handling and the characteristics for visual strength grading of softwood and hardwood poles, as well as the marking requirements; the methods of test to determine characteristic values for modulus of elasticity and bending strength of any population of wood poles and moisture content of solid wood poles; the requirements for durability and preservative treatment of wood poles. It is applicable to both softwood and hardwood poles.
Poteaux en bois — Exigences de base et méthodes d'essai
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 15206
First edition
2010-04-01
Timber poles — Basic requirements and
test methods
Poteaux en bois — Exigences de base et méthodes d'essai
Reference number
ISO 15206:2010(E)
©
ISO 2010
---------------------- Page: 1 ----------------------
ISO 15206:2010(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2010 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 15206:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Symbols and abbreviated terms .6
5 General requirements .7
5.1 Marking.7
5.2 Tree felling and wood preparation.7
5.3 Requirements for pole sizes, tolerances, permissible deviations and damage .7
5.4 Characteristic values .7
5.5 Strength-reducing characteristics.8
5.6 Other characteristics.10
5.7 Untreated wood poles.10
5.8 Preservative-treated wood poles .10
6 Test methods .11
6.1 Length and diameter .11
6.2 Knots and knot clusters.11
6.3 Slope of grain.11
6.4 Rate of growth .11
6.5 Bark pockets and rind galls .12
6.6 Mechanical damage.12
6.7 Fissures, splits and checks.12
6.8 Determination of moisture content.12
7 Evaluation of conformity .12
7.1 General .12
7.2 Initial type testing .12
7.3 Product assessment .13
8 Marking and declarations .13
8.1 Marking (mandatory) .13
8.2 Specific marking and declarations .13
8.3 Marking (optional) .14
Annex A (informative) Commonly used sizes for wood poles .15
Annex B (normative) Scheme for sampling preservative-treated wood poles by taking borings .16
Annex C (normative) Test method for bending properties — Cantilever method .17
Annex D (normative) Test method for bending properties — Four-point method.22
Annex E (normative) Test method for bending properties — Three-point method proof test .28
Annex F (normative) Determination of characteristic values.33
Bibliography.37
© ISO 2010 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 15206:2010(E)
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 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 in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15206 was prepared by Technical Committee ISO/TC 165, Timber structures.
iv © ISO 2010 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 15206:2010(E)
Introduction
This International Standard covers the requirements for grading and assignment of characteristic values that
can be used for the design of timber poles used as cantilevers and/or in compression.
It is the responsibility of the supplier to always ensure that all products supplied are in conformity with the
requirements of this International Standard and any other specification with which they are provided. This
International Standard is intended for the initial determination of the characteristic values for a given
population of poles and additional determination when there is a reason to suspect that the characteristics of a
population have changed.
This International Standard recognizes that there are many different visual strength-grading rules for timber in
use internationally. These have come into existence to allow for
⎯ different species or groups of species,
⎯ geographic origin,
⎯ different dimensional requirements,
⎯ varying requirements for different uses,
⎯ the quality of material available, and
⎯ historical influences or traditions.
Because of the diversity of existing standards for wood poles for overhead lines in use in different countries, it
is impossible to lay down a single set of acceptable visual grading rules.
This International Standard therefore gives the basic principles to be followed when drawing up regional,
national, local or buyer requirements for some characteristics and sets limits for others.
In laying down visual grading rules, two main factors are relevant:
⎯ they shall clearly define and limit the strength-affecting characteristics in poles, such that there is very
high confidence that poles supplied meet the required characteristic strength value;
⎯ the rules and the text are such that they can be easily understood and be suitable for implementation by
grading personnel.
This International Standard is also concerned with the durability characteristics of wood poles for overhead
power and telecommunication lines. It assumes that all such poles are constructed from round timber in which
the finished product comprises either a central core of heartwood surrounded by a zone of sapwood or the
heartwood only. Such assumptions dictate that where sapwood is present, preservative treatment is normally
required in order to provide the poles with sufficient enhanced durability, unless the amount of sapwood
present is such that its loss would not compromise the integrity of the pole during its service life and the
heartwood has sufficient natural durability as required by this International Standard.
Some timber species do not allow an easy differentiation between heartwood and sapwood. Various
standards provide recommendations to address this problem; for example, EN 351-1 and AS 2209:1994
(Appendix D) specify the method of treatment of such timber when preservation is required.
© ISO 2010 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 15206:2010(E)
Timber poles — Basic requirements and test methods
1 Scope
This International Standard specifies the requirements for grading, test methods, determination of
characteristic values, methods of specifying durability and sizes of single poles manufactured from solid
timber for telecommunications and electrical distribution purposes, either preservative treated or untreated,
under cantilever or compression loading.
It specifies the:
⎯ methods of measuring the sizes of solid wood poles for overhead transmission and telecommunication
lines and permissible deviations that are taken into account for the acceptance of the poles;
⎯ requirements for handling and the characteristics for visual strength grading of softwood and hardwood
poles, as well as the marking requirements;
⎯ methods of test to determine characteristic values for modulus of elasticity and bending strength of any
population of wood poles and moisture content of solid wood poles;
⎯ requirements for durability and preservative treatment of wood poles.
This International Standard is applicable to both softwood and hardwood poles.
This International Standard does not quantify the service life that can be expected from a pole.
NOTE This depends on its geographical location, the associated climate of its service environment and either the
natural durability of the heartwood of the species selected or the combination between selection of species, preservative
type, and requirements of retention and any incised zones.
It is not applicable to poles used as beams.
2 Normative references
The following referenced documents are indispensable for the application 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.
ISO 3166-1, Codes for the representation of names of countries and their subdivisions — Part 1: Country
codes
ISO 21887:2007, Durability of wood and wood-based products — Use classes
AS/NZS 1604.1, Specification for preservative treatment — Part 1: Sawn and round timber
AS 2209:1994, Timber — Poles for overhead lines
AS 2209:1994/Amd.1:1997, Timber — Poles for overhead lines
EN 252, Field test method for determining the relative protective effectiveness of a wood preservative in
ground contact
EN 351-1, Durability of wood and wood-based products — Preservative-treated solid wood — Part 1:
Classification of preservative penetration and retention
© ISO 2010 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 15206:2010(E)
EN 599-1, Durability of wood and wood-based products — Efficacy of preventive wood preservatives as
determined by biological tests — Part 1: Specification according to use class
EN 13183-1, Moisture content of a piece of sawn timber — Part 1: Determination by oven dry method
EN 13183-2, Moisture content of a piece of sawn timber — Part 2: Estimation by electrical resistance method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
bark pocket
bark that is partly or wholly enclosed in the wood
3.2
characteristic value
value corresponding to the 5th percentile of the statistical distribution of strength or the mean value of
modulus of elasticity, at a 75 % confidence level
3.3
charge
all the wood treated together in one treatment at one time (one complete treatment cycle)
3.4
crack
separation of wood fibres across the grain
NOTE These can be due to internal strains resulting from unequal longitudinal shrinkage, or the fibres being crinkled
by compression or other external forces
3.5
critical zone
1,6 m length of pole measured from a point 1 m above the nominal ground line to 600 mm below the nominal
ground line
NOTE If the pole is nominated as a stayed pole, an additional zone measured from the top of the pole equivalent to
the length between the nominal ground line and the butt of the pole shall be included.
3.6
decay
rot
decomposition of wood by fungi or other micro-organisms resulting in softening, progressive loss of mass and
strength, and often a change of texture and colour
3.7
direct testing
testing the preservative treatment achieved by the direct measurement of the penetration and retention of
preservative
3.8
double sweep
sweep characterized by two or more bends in one or several planes
3.9
fibre saturation point
FSP
state of a piece of timber when the cell walls are saturated with moisture but no moisture exists in the cell
cavities
2 © ISO 2010 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 15206:2010(E)
3.10
fissure
longitudinal separation of fibres
3.11
grain detector
device for detecting the angle of grain in timber
3.12
growth rate
mean number of growth rings per 25 mm
3.13
heart shake
radial end shake originating at the pith
3.14
incised zone
area of the lateral surface of the pole, which has undergone an incising process as an aid to securing deeper
and more uniform penetration of preservative
NOTE The minimum limit of the incised zone should be 400 mm above and 400 mm below the specified ground line
for the pole in service.
3.15
included sapwood
presence in the heartwood of a complete or incomplete ring, having the colour and the properties of sapwood
3.16
indirect testing
testing the preservative treatment achieved by measurement of a property found to exhibit a correlation
between itself and the penetration and retention of preservative
3.17
kerf
groove or slot formed in wood during the process of sawing
3.18
knot
portion of a branch embedded in wood
3.19
knot cluster
knots located such that no grain recovery is evident between adjacent knots
3.20
knot diameter
dimension of the knot measured on the surface of the pole and perpendicular to the axis of the pole
NOTE The diameter takes the entire knot into account, including the sapwood.
3.21
length
distance from the pole butt to the pole tip
3.22
maximum diameter
largest diameter of the pole at the section of measurement
© ISO 2010 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 15206:2010(E)
3.23
minimum diameter
smallest diameter of the pole at the section of measurement
3.24
moisture content
ratio of the mass of the quantity of water in a material to the mass of the dry material
3.25
nominal diameter
3.25.1
nominal diameter
〈pole with 5 % or less ovality〉 theoretical diameter, usually the diameter measured at the nominal ground line
3.25.2
nominal diameter
〈pole with greater than 5 % ovality〉 minimum diameter
3.26
nominal ground line
plane normal to the axis of the pole usually located at a distance of 600 mm plus 10 % of the nominal length
from the butt end
3.27
ovality
difference between the maximum and minimum diameter at a cross-section expressed as a percentage of the
minimum diameter
3.28
pith
innermost part of the pole
3.29
pole
long, round timber for use in a free-standing application
3.30
pole butt
lowermost point of the thicker end of the pole
3.31
pole tip
uppermost point of the narrow end of the pole
3.32
population
group of poles defined by having the same species, source and grade
3.33
resin pocket
cavity that contains or has previously contained resin
NOTE This may be similar to rind galls.
3.34
rind gall
surface wound that has been partially enclosed by the growth of a tree
4 © ISO 2010 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 15206:2010(E)
3.35
ring shake
fissure following the line of a growth ring
3.36
sample
one or more poles taken from a single population
3.37
sampling unit
single preservative-treated pole taken from a charge
3.38
scribe
cranked rod with a swivel handle and a needle at the tip, set to a slight trailing angle
NOTE This is used as a grain detector by pressing the needle into the timber and drawing it across the surface in the
apparent direction of the grain.
3.39
section of maximum stress
section of pole where the diameter equals 1,5 times the diameter at the point of application of load if this
section is above ground line; otherwise the actual ground-line section
3.40
short crook
local deflection
natural deviation of the axis of the pole occurring on a length less than 1,5 m
3.41
simple sweep
sweep characterized by one bend only
3.42
slope of grain
divergence of the direction of the fibres from the longitudinal axis of the piece
NOTE The slope of grain in poles is usually observed as an inclination of the wood cells on the surface, which is
referred to in some International Standards as spiral growth angle.
3.43
standard size pole
pole of a size 8 m or 10 m long and 180 mm to 220 mm diameter at 1,5 m from the butt end, and used for the
determination of characteristic values
3.44
star shake
two or more heart shakes
3.45
sweep
deviation of the longitudinal axis of round timber from a straight line
3.46
taper
gradual reduction in diameter of a stem along its height or round timber along its length
3.47
theoretical diameter
diameter of a circle with the same circumference as the actual circumference at the section of measurement
© ISO 2010 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 15206:2010(E)
4 Symbols and abbreviated terms
d nominal diameter at assumed ground line, in millimetres
g
d nominal diameter at point of load application, in millimetres
q
d nominal diameter at section of maximum stress, in millimetres
max
E modulus of elasticity parallel to grain in bending, in newtons per square millimetre
f bending strength — maximum stress at assumed ground line or point of maximum stress if this is
m
above the assumed ground line, in newtons per square millimetre
I second moment of area of cross-section at point of load application, in millimetres to the fourth
q
power
l pole length measured from butt to tip, in millimetres
l distance from butt to assumed ground line, in millimetres
g
l distance from butt to section of maximum stress or ground line, whichever is the greater, in
g
millimetres
l distance from tip to position of applied load, in millimetres
q
Q applied load, in newtons
s − s movement of load application point parallel to longitudinal axis of the pole during testing, in
a 0
millimetres (see Figure C.2)
t − t deflection at point of load application, in millimetres (see Figure C.2)
a 0
E mean value of modulus of elasticity parallel to direction of grain, in newtons per square millimetre
mean
f characteristic value of bending strength, in newtons per square millimetre
m, k
f sample fifth percentile of bending strength, in newtons per square millimetre
m, 05
k statistical factor
m mean value (the variable is given in parentheses)
m(E) sample mean values of modulus of elasticity, in newtons per square millimetre
m( f ) sample mean value of bending strength, in newtons per square millimetre
m
m( f ) mean of f values
m, 05 m, 05
n number of test poles in a sample
s standard deviation (the variable is given in parentheses)
s(E) sample standard deviation of modulus of elasticity, in newtons per square millimetre
s( f ) sample standard deviation of bending strength, in newtons per square millimetre
m
6 © ISO 2010 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 15206:2010(E)
5 General requirements
5.1 Marking
The manufacturer shall declare the species and ensure that all poles are clearly marked to identify the species,
in accordance with Clause 8.
NOTE Common names are different depending on language version.
5.2 Tree felling and wood preparation
5.2.1 Tree felling
At the time the trees are felled, it is advisable to ensure that the rising sap is low, except for timber which is to
be treated by a sap displacement process. If the trees are felled when the sap is high, it is recommended that
measures be taken to avoid pre-treatment decay or attack by insects.
5.2.2 Handling of untreated wood
The method of handling shall avoid any damage that could alter the mechanical performance and durability of
the pole, as well as the suitability of the pole for preservative treatment. Species permitted for use in poles are
generally specified in the referenced local standards.
5.2.3 Mechanical pre-treatments
Where poles are mechanically pre-treated before preservation, e.g. through incising, testing in accordance
with Clause 6 shall be carried out after the mechanical pre-treatment.
5.3 Requirements for pole sizes, tolerances, permissible deviations and damage
For poles used in structural applications, the minimum diameter of a pole shall be not less than 80 % of the
maximum diameter at any cross-section over a maximum of 80 % of the length of the pole.
The manufacturer shall declare the size of the poles, specified by the overall length, the nominal diameter at
1,5 m from the butt and the nominal diameter at the tip, measured in accordance with 6.1. The permissible
dimensional tolerances are:
⎯ length: −1 % or +2 %;
⎯ diameter: −0 or +40 mm unless otherwise declared by the manufacturer.
NOTE A list of commonly used pole sizes (minimum nominal diameter at 1,5 m from the butt, and length) is given in
Annex A.
5.4 Characteristic values
The manufacturer shall declare structural properties in accordance with 8.2.
© ISO 2010 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO 15206:2010(E)
5.5 Strength-reducing characteristics
5.5.1 Knots
The maximum dimension of knots, knot holes and knot clusters shall be recorded in the following manner:
a) individual knots or knot clusters — maximum diameter of knots or knot clusters, expressed as a factor of
the circumference of the pole at the point where the knot occurs;
b) multiple knots, etc. — maximum sum of all the knot diameters in any 300 mm length of the pole,
expressed as a factor of the circumference of the pole at the midpoint of the 300 mm length (e.g.
factor = knot diameter in mm/circumference of pole at cross-section in millimetres).
The measurement of the individual knot or knot clusters shall be according to 6.2.
Different limitations on knot sizes may be specified for different portions of the pole, e.g. the top third of poles
over 13 m long could have different knot limitations from the rest of the pole.
5.5.2 Slope of grain
The slope of grain relative to the longitudinal axis shall be measured according to 6.3. Significant changes in
the slope of grain shall not be allowed.
5.5.3 Heartwood
For hardwood poles, the minimum area of heartwood when measured at the butt shall be recorded.
Dimensions in millimetres
1 case 2: multiple knots in any 300 mm length of the pole
2 case 1: individual knots or knot clusters
Figure 1 — Measurement of knots
5.5.4 Rate of growth
If the rate of growth is required, it shall be declared as the minimum number of growth rings per 25 mm when
measured in accordance with 6.4 (i.e. maximum growth rate).
8 © ISO 2010 – All rights reserved
---------------------- Page: 13 ----------------------
ISO 15206:2010(E)
5.5.5 Straightness
A single sweep shall be permitted to the extent that a straight line drawn from the centre of the tip to the
centre of the butt shall remain in the pole.
Where double sweep and short crook exist, these shall be declared by the manufacturer.
5.5.6 Bark pockets and rind galls
Bark pockets and rind galls shall be permitted in the first 1 m of length from the butt. Above the first 1 m length
from the butt, bark pockets and rind galls shall be measured according to 6.5. Depth, position and number
shall not exceed those given for mechanical damage. They shall be specified by length, width and depth,
expressed as a percentage of the nominal diameter of the pole at that point.
5.5.7 Mechanical damage
Mechanical damage shall not extend to a depth that will reduce the diameter by more than 5 % of the
diameter at any cross-section when measured in accordance with 6.6. No more than two occurrences of
mechanical damage shall be permitted and no part of these shall be less than 500 mm apart.
5.5.8 Ring and star shake
The tip shall be free from ring shake or star shakes with five or more points. At the butt, one complete ring or
one star shake is acceptable, provided not more than two points extend to within 5 mm from the pole
circumference. If they extend to the circumference, they shall not extend along the pole more than 500 mm
from the butt.
5.5.9 Fissures, splits and checks
Seasoning fissures and splits along the grain are expected and are not recognized as defects, provided they
do not have a depth greater than half the diameter at one point along the pole or do not exceed 50 % of the
length of the pole, when measured according to 6.7.
5.5.10 Damage
Any damage in poles manufactured from trees subjected to snow breakage, frost damage, windfall or forest
fires, shall be limited to ensure that any such poles meet the grading requirements of this International
Standard and are fit for purpose.
5.5.11 Decay and insects
Poles shall be sound and free from decay and attack by insects. Minor insect holes are acceptable provided
these are, either not larger than 1,5 mm in diameter and do not exceed 5 in number, or not larger than 1,0 mm
in diameter and do not exceed 20 in number, evenly distributed in any 100 mm length of the pole.
5.5.12 Included sapwood
No included sapwood in heartwood shall be permitted in hardwood poles.
5.5.13 Cracks
Cracks across the pole and the grain shall not be permitted.
© ISO 2010 – All rights reserved 9
----------------
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.