ISO 128-2:2020
(Main)Technical product documentation (TPD) — General principles of representation — Part 2: Basic conventions for lines
Technical product documentation (TPD) — General principles of representation — Part 2: Basic conventions for lines
This document establishes the types of lines used in technical drawings (e.g. diagrams, plans or maps), their designations and their configurations, as well as general rules for the draughting of lines. In addition, this document specifies general rules for the representation of leader and reference lines and their components as well as for the arrangement of instructions on or at leader lines in technical documents. Annexes have been provided for specific information on mechanical, construction and shipbuilding technical drawings. For the purposes of this document the term "technical drawing" is interpreted in the broadest possible sense encompassing the total package of documentation specifying the product (workpiece, subassembly, assembly).
Documentation technique de produits (TPD) — Principes généraux de représentation — Partie 2: Conventions de base pour les traits
Le présent document établit les types de traits utilisés dans les dessins techniques (par exemple schémas, plans ou cartes), leurs désignations et leurs configurations, ainsi que les règles générales pour le tracé de traits. De plus, le présent document spécifie des règles générales pour la représentation des lignes repères et traits de référence et leurs composants, ainsi que pour la disposition des instructions sur ou aux lignes repères dans les documents techniques. Des annexes ont été prévues pour des informations spécifiques sur les dessins industriels, dessins de construction et dessins de construction navale. Pour les besoins du présent document, le terme «dessin technique» est interprété au sens le plus large possible, englobant l'ensemble de la documentation spécifiant le produit (pièce, sous-ensemble, ensemble).
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INTERNATIONAL ISO
STANDARD 128-2
First edition
2020-07
Technical product documentation
(TPD) — General principles of
representation —
Part 2:
Basic conventions for lines
Documentation technique de produits (TPD) — Principes généraux de
représentation —
Partie 2: Conventions de base pour les traits
Reference number
ISO 128-2:2020(E)
©
ISO 2020
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ISO 128-2:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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ISO 128-2:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Types of lines . 3
4.1 General . 3
4.2 Basic types . 3
4.3 Line sub types . 4
4.4 Variations of the basic types of lines . 4
4.5 Combinations of lines with the same length . 4
4.5.1 Arrangement of two or more lines parallel to each other . 4
4.5.2 Arrangement of two different types of lines . 5
4.5.3 Arrangement of two continuous lines parallel to each other with regularly
recurring connecting elements between them . 5
4.5.4 Arrangement of regularly recurring geometric pictorial elements in
association with continuous lines . 5
5 Line dimensions . 6
5.1 Line width . 6
5.2 Deviation in line width . 6
5.3 Configuration of lines . 6
6 Draughting of lines . 7
6.1 Spacing . 7
6.2 Junctions . 7
6.2.1 Types . 7
6.2.2 Representation . 9
6.3 Location of a second line .10
6.4 Hierarchy of overlapping lines .10
7 Colours .11
8 Designation .11
9 Basic conventions and applications for leader lines and reference lines .11
9.1 Presentation of leader lines .11
9.2 Representation of reference lines .14
9.3 Indication of instructions.15
Annex A (informative) Preparation of lines by CAD systems .17
Annex B (normative) Lines on construction technical drawings .30
Annex C (informative) Examples of application on construction technical drawings .33
Annex D (normative) Types of lines and their application on mechanical engineering
technical drawings .39
Annex E (informative) Examples of application on mechanical engineering technical drawings.43
Annex F (normative) Types of lines and their application on shipbuilding technical drawings .56
Annex G (informative) Application examples of the different types of lines on shipbuilding
technical drawings .58
Bibliography .69
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ISO 128-2:2020(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 10, Technical product documentation.
This first edition cancels and replaces the following documents:
— ISO 128-20:1996
— ISO 128-21:1997
— ISO 128-22:1999
— ISO 128-23:1999
— ISO 128-24:2014
— ISO 128-25:1999
The main changes to these documents are as follows:
— harmonization of the former parts listed above;
— introduction of the hierarchy of overlapping lines.
A list of all parts in the ISO 128 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO 128-2:2020(E)
Introduction
ISO 128-2 contains generally applicable rules for the presentation of lines in all kinds of technical
product documentation.
All figures in this document have been drawn in first-angle projection. It should be understood that
third-angle projection or other methods could have been used equally well without prejudice to the
principles established.
The application of lines within drawings of special technical fields varies considerably. Therefore, rules
of application specific to technical fields are given in Annexes B to G.
Annex A provides information for the calculation of the most important basic types of non-continuous
lines according to types of lines and their line elements.
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INTERNATIONAL STANDARD ISO 128-2:2020(E)
Technical product documentation (TPD) — General
principles of representation —
Part 2:
Basic conventions for lines
1 Scope
This document establishes the types of lines used in technical drawings (e.g. diagrams, plans or
maps), their designations and their configurations, as well as general rules for the draughting of lines.
In addition, this document specifies general rules for the representation of leader and reference lines
and their components as well as for the arrangement of instructions on or at leader lines in technical
documents. Annexes have been provided for specific information on mechanical, construction and
shipbuilding technical drawings.
For the purposes of this document the term “technical drawing” is interpreted in the broadest
possible sense encompassing the total package of documentation specifying the product (workpiece,
subassembly, assembly).
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.
ISO 128-3, Technical drawings — General principles of representation — Part 3: Views, sections and cuts
ISO 128-15, Technical product documentation (TPD) — General principles of presentation — Part 15:
Presentation of shipbuilding drawings
ISO 129-1, Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 1:
General principles
ISO 129-5, Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 5:
Dimensioning of structural metal work
ISO 1101, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form,
orientation, location and run-out
ISO 2203, Technical drawings — Conventional representation of gears
ISO 2538-2, Geometrical product specifications (GPS) — Wedges — Part 2: Dimensioning and tolerancing
ISO 2553, Welding and allied processes — Symbolic representation on drawings — Welded joints
ISO 3040, Geometrical product specifications (GPS) — Dimensioning and tolerancing — Cones
ISO 3766, Construction drawings — Simplified representation of concrete reinforcement
ISO 4463-1, Measurement methods for building — Setting-out and measurement — Part 1: Planning and
organization, measuring procedures, acceptance criteria
ISO 4463-3, Measurement methods for building — Setting-out and measurement — Part 3: Check-lists for
the procurement of surveys and measurement services
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ISO 128-2:2020(E)
ISO 5261, Technical drawings — Simplified representation of bars and profile sections
ISO 5455, Technical drawings — Scales
ISO 5456-4, Technical drawings — Projection methods — Part 4: Central projection
ISO 5459, Geometrical product specifications (GPS) — Geometrical tolerancing — Datums and datum systems
ISO 6410-1, Technical drawings — Screw threads and threaded parts — Part 1: General conventions
ISO 6428, Technical drawings — Requirements for microcopying
ISO 7437, Technical drawings — Technical drawings — Construction drawings — General rules for
execution of production drawings for prefabricated structural components
ISO 7519, Technical drawings — Construction drawings — General principles of presentation for general
arrangement and assembly drawings
ISO 8560, Technical drawings — Construction drawings — Representation of modular sizes, lines and grids
ISO 10110-1, Optics and photonics — Preparation of drawings for optical elements and systems —
Part 1: General
ISO 10135, Geometrical product specifications (GPS) — Drawing indications for moulded parts in technical
product documentation (TPD)
ISO 10209, Technical product documentation — Vocabulary — Terms relating to technical drawings,
product definition and related documentation
ISO 11091, Construction drawings — Landscape drawing practice
ISO 12671, Thermal spraying — Thermally sprayed coatings — Symbolic representation on drawings
ISO 15785, Technical drawings — Symbolic presentation and indication of adhesive, fold and pressed joints
ISO 15787, Technical product documentation — Heat-treated ferrous parts — Presentation and indications
ISO 16792, Technical product documentation — Digital product definition data practices
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10209 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
graphical basic element
continuous graphical object with rounded or squared end shape which is represented in any way (e.g.
straight, curved), which has a length and a width
Note 1 to entry: See Figure A.1.
3.2
dot
graphical basic element (3.1) having a length equal to the width, d
Note 1 to entry: See Figure A.2.
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ISO 128-2:2020(E)
3.3
line
set of one or more graphical basic elements (3.1) having a length of more than the width
Note 1 to entry: See Figure A.3.
3.4
technical drawing
drawing showing a technical installation, process or product with a view to clarifying its structure and
enabling its construction
[SOURCE: ISO 5127:2017, 3.4.7.54, modified — Note 1 to entry removed.]
4 Types of lines
4.1 General
The line type designation consists of a combination of a basic line type and a subtype, depending on the
line width, see 4.2.
For the purposes of this document a line type application number is used to number the application
examples for the line types.
For applying line types to construction technical drawings Annex B shall be applied. For applying line
types to mechanical engineering technical drawings Annex D shall be applied. For applying line types
to ship building technical drawings Annex F shall be applied.
4.2 Basic types
The basic line types are given in Table 1.
Table 1 — Basic line types
No. Representation Description
01 Continuous line
02 Dashed line
03 Dashed spaced line
04 Long-dashed dotted line
05 Long-dashed double-dotted line
06 Long-dashed triplicate-dotted line
07 Dotted line
08 Long-dashed short-dashed line
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ISO 128-2:2020(E)
Table 1 (continued)
No. Representation Description
Long-dashed double-short-dashed
09
line
10 Dashed dotted line
11 Double-dashed dotted line
12 Dashed double-dotted line
13 Double-dashed double-dotted line
14 Dashed triplicate-dotted line
15 Double-dashed triplicate-dotted line
4.3 Line sub types
The line sub types are given in Table 2.
Table 2 — Line sub types
Sub-type
Representation Description
a
no.
.1 Narrow
.2 Wide
.3 Extra wide
a
Line identification structure
4.4 Variations of the basic types of lines
The straight lines in Table 1 and the line widths of Table 2 can have variations as shown in Table 3.
Table 3 — Line variations
Representation Description
Uniform wavy continuous line
Uniform spiral continuous line
Uniform zigzag continuous line
Freehand / freeform curve continu-
ous line
NOTE Table 3 contains only variations of the basic type of line No. 01. Variations of the basic types of Nos. 02 to 15 are
possible and are presented in the same way.
4.5 Combinations of lines with the same length
4.5.1 Arrangement of two or more lines parallel to each other
For examples see Figure 1.
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ISO 128-2:2020(E)
Figure 1 — Example of lines parallel to each other
4.5.2 Arrangement of two different types of lines
a) With different line widths superimposed. See Figure 2 a) and b) for examples.
a) A continuous line and a dotted line b) A continuous line and a dashed spaced line
Figure 2 — Example of superimposed lines
b) Arranged next to each other. See Figure 3 for an example.
Figure 3 — Two continuous narrow lines either side of a wide dashed line
4.5.3 Arrangement of two continuous lines parallel to each other with regularly recurring
connecting elements between them
See Figure 4 a) and b) for examples.
a) Filled circular elements b) Filled trapezoidal elements
Figure 4 — Example of lines parallel to each other with regularly recurring connecting
elements
4.5.4 Arrangement of regularly recurring geometric pictorial elements in association with
continuous lines
a) Without interruption of a continuous line. See Figure 5 for examples.
Figure 5 — Without interruption of a continuous line
b) With interruption of a continuous line. See Figure 6 for examples.
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ISO 128-2:2020(E)
Figure 6 — With interruption of a continuous line
5 Line dimensions
5.1 Line width
The width, d, of all types of lines shall be one of the following depending on the type and size of the
technical drawing. This series is based on a common ratio 1: √2 (≈1:1,4).
0,13 mm; 0,18 mm; 0,25 mm; 0,35 mm; 0,5 mm; 0,7 mm; 1 mm; 1,4 mm; 2 mm.
The widths of extra wide, wide and narrow lines are in the ratio 4:2:1.
The line width of any one line shall be constant throughout the whole line.
See Annexes B, D and F for information on line widths pertaining to construction, mechanical and
shipbuilding technical drawings.
5.2 Deviation in line width
Line widths can deviate from those specified in 5.1 providing that it is possible to differentiate
unambiguously between two adjacent lines with different widths. If technical drawing equipment
which produces constant line width is used, the deviation in line width between two such lines shall not
be greater than ± 0,1d.
5.3 Configuration of lines
For the preparation of technical drawings, the lengths of line elements should conform to those of
Table 4.
Table 4 — Lengths of line elements
Drawing element Line type no. Length
04 to 07 and
Dot ≤ d
10 to 15
02 and
Gap 3d
04 to 15
Short dash 08 and 09 6d
02, 03 and
Dash 12d
10 to 15
04 to 06,
Long dash ≈24d
08 and 09
Space 03 18d
NOTE The lengths shown in this table are valid for line elements with semi-circular and
squared ends. In the case of line elements with semi-circular ends, the length of the line
element corresponds to the distance covered by a technical pen (with a tubular tip and
using India ink) from the origin up to the end of the line element. The total length of such
a line element is the sum of the length shown in this table, plus d.
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ISO 128-2:2020(E)
Formulae for the calculation of some of the basic types of lines and line elements are given in Annex A.
The formulae are intended to facilitate the preparation of technical drawings using computer-aided
design (CAD) systems.
6 Draughting of lines
6.1 Spacing
The minimum space between parallel lines should not be less than 0,7 mm.
In certain cases when computer-aided technical drawing techniques are used, the spacing of lines on
the technical drawing does not represent the actual spacing, for example for the representation of
screw threads. This has to be considered when data sets are established, for example for the operation
of machine tools.
6.2 Junctions
6.2.1 Types
The basic types of lines, nos. 02 to 06 and nos. 08 to 15, should meet at a dash to avoid ambiguity; see
Figures 7 to 12.
Figure 7 — Long-dashed short-dashed lines intersecting as a cross
Figure 8 — Dashed lines intersecting as a cross
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ISO 128-2:2020(E)
Figure 9 — Dashed lines intersecting as a partial cross
Figure 10 — Four dashed lines meeting at an intersection
Figure 11 — Dash dotted lines intersecting as a cross and dashed lines meeting at corners
Figure 12 — Dashed lines meeting at corners and at intersection
Lines of basic type no. 07 should meet at a dot to avoid ambiguity, see Figure 13.
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ISO 128-2:2020(E)
Figure 13 — Dotted lines intersecting at a dot
6.2.2 Representation
Techniques for applying the recommendations of 6.2.1 are to start the lines at the junction (see
Figure 14) or by using a complete, or partial, cross or Y (see Figures 15 and 16).
Figure 14 — Partial cross intersection
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ISO 128-2:2020(E)
Figure 15 — Cross intersection
Figure 16 — Y intersection
6.3 Location of a second line
Two different ways of presenting two parallel lines are shown in Figures 17 and 18.
Figure 17 — Example of parallel lines with solid line above dashed line
Figure 18 — Example of parallel lines with dashed line above solid line
6.4 Hierarchy of overlapping lines
The rules of overlapping types of lines are defined in Annex D.
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ISO 128-2:2020(E)
7 Colours
Lines shall be drawn in black or white depending on the colour of the background. By default, lines
are black on a white background. Other standardized colours may also be used for technical drawing
standardized lines. In this case, the meaning of the colours shall be explained.
8 Designation
The designation of the basic types of lines shall comprise the following elements in the order given,
with spaces between the elements:
a) “Line”;
b) reference to this document;
c) dash separator;
d) the number of the basic type in accordance with Table 1;
e) the multiplication sign “×”;
f) the line width in accordance with 5.1;
g) forward slash (when the colour is indicated);
h) colour (when indicated).
EXAMPLES
Designation of a line of type no. 03 (03), line width 0,25 mm (0,25):
Line ISO 128-2 - 03 × 0,25
Designation of a line of type no. 05 (05), line width 0,13 mm (0,13) and blue in colour:
Line ISO 128-2 - 05 × 0,13/blue
9 Basic conventions and applications for leader lines and reference lines
9.1 Presentation of leader lines
Leader lines are executed as continuous narrow lines (type 01.1) in accordance with this document.
They are drawn at an angle to the relevant representation and/or the frame limiting the drawing sheet,
and not parallel to nearby lines, such as hatching lines. The inclination to the relevant lines shall be >15°.
See Figures 19 to 31.
Leader lines may be drawn with sharp kinks (see Figure 23), and two or more leader lines may
start from the same point (see Figures 20, 23, 25, 26 and 29). They should not cross other leader
lines (see Figure 23) except when the leader line starts from the same point and is colinear (see
Figure 25, 26 and 29), reference lines or indications, such as graphical symbols or dimensional values.
Leader lines shall terminate at the end which touches the features as follows:
— with a closed and filled arrowhead or a closed arrowhead as per ISO 129-1 if the leader line ends
at lines which represent outlines or edges of parts, piping or cables in plans, charts or diagrams;
arrowheads are also drawn at crossing points of these lines with other lines, for example lines of
symmetry (see the examples given in Figures 19 to 25);
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ISO 128-2:2020(E)
If several parallel lines have to be designated, oblique strokes instead of arrowheads are permitted (see
IEC 61082-1). See the example given in Figure 26.
— with a dot (d = 5 × line width) if the leader line ends on the surface of an object (see the examples
given in Figures 27 to 29);
— without any termination if the leader line ends at another line, for example dimension line or line of
symmetry (see the examples given in Figures 30 and 31).
Figure 19 — Example of a leader line terminating at the edge of a diameter
Figure 20 — Example of leader lines starting at the same point and terminating at part edges
Figure 21 — Example of leader lines terminating at outlines
Figure 22 — Example of leader lines not overlapping cross section lines
Figure 23 — Example of a leader line with a sharp kink
Figure 24 — Example of a leader line terminating a the crossing point of two lines
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ISO 128-2:2020(E)
Figure 25 — Example of colinear leader lines starting from the same point and terminating
with arrows
Figure 26 — Example of a colinear leader lines starting from the same point and terminating
with oblique strokes
Figure 27 — Example of a leader line terminating with a dot to a surface area
Figure 28 — Example of a leader line terminating with a dot to a surface
Figure 29 — Example of colinear leader lines starting from the same point and terminating
with dots
Figure 30 — Example of a leader line ending at a dimension line without any termination mark
Figure 31 — Example of a leader line without any termination mark
© ISO 2020 –
...
NORME ISO
INTERNATIONALE 128-2
Première édition
2020-07
Documentation technique de produits
(TPD) — Principes généraux de
représentation —
Partie 2:
Conventions de base pour les traits
Technical product documentation (TPD) — General principles of
representation —
Part 2: Basic conventions for lines
Numéro de référence
ISO 128-2:2020(F)
©
ISO 2020
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ISO 128-2:2020(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,
y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut
être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
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Tél.: +41 22 749 01 11
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Publié en Suisse
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ISO 128-2:2020(F)
Sommaire Page
Avant-propos .iv
Introduction .v
1 Domaine d'application . 1
2 Références normatives . 1
3 Termes et définitions . 2
4 Types de traits . 3
4.1 Généralités . 3
4.2 Types de base . 3
4.3 Sous-types de traits . 4
4.4 Variations des types de traits de base . 4
4.5 Combinaisons de traits de même longueur. 5
4.5.1 Combinaison de deux traits parallèles entre eux ou plus . 5
4.5.2 Combinaison de deux différents types de traits . 5
4.5.3 Combinaison de deux traits continus parallèles avec des éléments de
liaison régulièrement répétés. 5
4.5.4 Combinaison d’éléments picturaux géométriques régulièrement répétés
en association avec des traits continus . 5
5 Dimensions des traits . 6
5.1 Largeur des traits . 6
5.2 Écart dans la largeur de trait . 6
5.3 Configuration des traits . 6
6 Tracé de traits . 7
6.1 Espacement . 7
6.2 Jonctions . 7
6.2.1 Types . 7
6.2.2 Représentation . 9
6.3 Emplacement d'un deuxième trait .10
6.4 Hiérarchie des traits chevauchants .10
7 Couleurs .11
8 Désignation .11
9 Conventions de base et applications pour les lignes repères et traits de référence .11
9.1 Présentation des lignes repères .11
9.2 Représentation des traits de référence .14
9.3 Indication des instructions .15
Annexe A (informative) Préparation des traits par systèmes CAO .17
Annexe B (normative) Traits dans des dessins techniques de construction .30
Annexe C (informative) Exemples d'application sur des dessins techniques de construction .33
Annexe D (normative) Types de traits et leur application dans des dessins techniques
industriels .40
Annexe E (informative) Exemples d'application sur des dessins techniques industriels .44
Annexe F (normative) Types de traits et leur application dans des dessins techniques de
construction navale .57
Annexe G (informative) Exemples d’application des différents types de traits dans des
dessins techniques de construction navale .60
Bibliographie .72
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ISO 128-2:2020(F)
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes
nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est
en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.
L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d'approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/ directives).
L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de
brevets reçues par l'ISO (voir www .iso .org/ brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion
de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir www .iso .org/ avant -propos.
Le présent document a été élaboré par le comité technique ISO/TC 10, Documentation de produits.
Cette première édition annule et remplace les documents suivants:
— ISO 128-20:1996
— ISO 128-21:1997
— ISO 128-22:1999
— ISO 128-23:1999
— ISO 128-24:2014
— ISO 128-25:1999
Les principales modifications par rapport à ces documents sont les suivantes:
— l’harmonisation des anciennes parties citées ci-dessus;
— l’introduction de la hiérarchie des traits chevauchants.
Une liste de toutes les parties de la série ISO 128 se trouve sur le site web de l’ISO.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www .iso .org/ members .html.
iv © ISO 2020 – Tous droits réservés
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ISO 128-2:2020(F)
Introduction
L'ISO 128-2 comprend des règles généralement applicables pour la représentation de traits dans toutes
sortes de documentations techniques de produits.
Toutes les figures dans le présent document ont été dessinées selon la projection du premier dièdre. Il
convient de comprendre que la projection du troisième dièdre ou tout autres méthodes pourraient aussi
bien être utilisées sans préjudice pour les principes établis.
L’application des traits dans les dessins de domaines techniques spéciaux varie considérablement.
Par conséquent, les règles d’application spécifiques aux champs techniques sont données dans les
Annexes B à G.
L’Annexe A fournit des informations pour le calcul des plus importants types de traits interrompus de
base conformément aux types de traits et à leurs éléments de traits.
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NORME INTERNATIONALE ISO 128-2:2020(F)
Documentation technique de produits (TPD) — Principes
généraux de représentation —
Partie 2:
Conventions de base pour les traits
1 Domaine d'application
Le présent document établit les types de traits utilisés dans les dessins techniques (par exemple schémas,
plans ou cartes), leurs désignations et leurs configurations, ainsi que les règles générales pour le tracé
de traits. De plus, le présent document spécifie des règles générales pour la représentation des lignes
repères et traits de référence et leurs composants, ainsi que pour la disposition des instructions sur ou
aux lignes repères dans les documents techniques. Des annexes ont été prévues pour des informations
spécifiques sur les dessins industriels, dessins de construction et dessins de construction navale.
Pour les besoins du présent document, le terme «dessin technique» est interprété au sens le plus
large possible, englobant l'ensemble de la documentation spécifiant le produit (pièce, sous-ensemble,
ensemble).
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.
Pour les références non datées, la dernière édition du document de référence s'applique (y compris les
éventuels amendements).
ISO 128-3, Dessins techniques — Principes généraux de représentation — Partie 3: Vues, sections et coupes
ISO 128-15, Documentation technique de produits (TPD) — Principes généraux de représentation — Partie
15: Représentation des dessins de construction navale
ISO 129-1, Documentation technique de produits — Représentation des dimensions et tolérances — Partie
1: Principes généraux
ISO 129-5, Technique du produit documentation — Indication des cotes et tolérances — Partie 5: Cotes des
ouvrages de structure métallique
ISO 1101, Spécification géométrique des produits (GPS) — Tolérancement géométrique — Tolérancement
de forme, orientation, position et battement
ISO 2203, Dessins techniques — Représentation conventionnelle des engrenages
ISO 2538-2, Spécification géométrique des produits (GPS) — Coins — Partie 2: Cotation et tolérancement
ISO 2553, Soudage et techniques connexes — Représentations symboliques sur les dessins —
Assemblages soudés
ISO 3040, Spécification géométrique des produits (GPS) — Cotation et tolérancement — Cônes
ISO 3766, Dessins de construction — Représentation simplifiée des armatures de béton
ISO 4463-1, Méthodes de mesurage pour la construction — Piquetage et mesurage — Partie 1: Planification
et organisation, procédures de mesurage et critères d'acceptation
© ISO 2020 – Tous droits réservés 1
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ISO 128-2:2020(F)
ISO 4463-3, Méthodes de mesurage pour la construction — Piquetage et mesurage — Partie 3: Listes de
contrôle pour la fourniture de levés topographiques et de prestations de mesurage
ISO 5261, Dessins techniques — Représentation simplifiée des barres et des profilés
ISO 5455, Dessins techniques — Échelles
ISO 5456-4, Dessins techniques — Méthodes de projection — Partie 4: Projection centrale
ISO 5459, Spécification géométrique des produits (GPS) — Tolérancement géométrique — Références
spécifiées et systèmes de références spécifiées
ISO 6410-1, Dessins techniques — Filetages et pièces filetées — Partie 1: Conventions générales
ISO 6428, Dessins techniques — Conditions requises pour la micrographie
ISO 7437, Dessins techniques — Dessins de construction — Règles générales pour l'élaboration de dessins
d'exécution pour des composants de structure préfabriqués
ISO 7519, Dessins techniques — Dessins de construction — Principes généraux de présentation pour des
dessins d'ensemble et d'assemblage
ISO 8560, Dessins techniques — Dessins de construction — Représentation des dimensions, lignes et
quadrillages modulaires
ISO 10110-1, Optique et photonique — Indications sur les dessins pour éléments et systèmes optiques —
Partie 1: Généralités
ISO 10135, Spécification géométrique des produits (GPS) — Indications sur les dessins pour pièces moulées
dans la documentation technique de produits (TPD)
ISO 10209, Documentation technique de produits — Vocabulaire — Termes relatifs aux dessins techniques,
à la définition de produits et à la documentation associée
ISO 11091, Dessins de construction — Pratique en matière de dessins de paysages
ISO 12671, Projection thermique — Revêtements appliqués par projection thermique — Représentation
symbolique sur les dessins
ISO 15785, Dessins techniques — Représentation symbolique et indication des assemblages collés, repliés
et clinchés
ISO 15787, Documentation technique de produits — Produits ferreux traités thermiquement — Présentation
et indications
ISO 16792, Documentation technique de produits — Données de définition d’un produit
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions donnés dans l’ISO 10209, ainsi que les
suivants s'appliquent.
L'ISO et l'IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— ISO Online browsing platform: disponible à l'adresse https:// www .iso .org/ obp
— Electropedia IEC: disponible à l’adresse http:// www .electropedia .org/
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ISO 128-2:2020(F)
3.1
élément graphique de base
objet graphique continu avec une forme d’extrémité arrondie ou carrée qui est représenté d'une
certaine manière (par exemple, droit, arrondi), qui a une longueur et une largeur
Note 1 à l'article: voir la Figure A.1
3.2
point
élément graphique de base (3.1) ayant une longueur égale à la largeur, d
Note 1 à l'article: voir la Figure A.2
3.3
trait
ensemble d'un ou de plusieurs éléments graphiques de base (3.1) ayant une longueur supérieure à la largeur
Note 1 à l'article: voir la Figure A.3
3.4
dessin technique
dessin montrant une installation technique, un procédé ou un produit dans le but de clarifier sa
structure et permetant sa construction
[SOURCE: ISO 5127:2017, 3.4.7.54, modifié — Note 1 à l'article supprimé.]
4 Types de traits
4.1 Généralités
La désignation d’un type de trait comprend une combinaison d'un type de trait de base et d'un sous-
type, en fonction de la largeur du trait, voir 4.2.
Pour les besoins du présent document un nombre d'application du type de trait est utilisé pour
numéroter les exemples d'application pour les types de trait.
Pour appliquer les types de trait aux dessins techniques de construction, l'Annexe B doit être utilisée.
Pour appliquer les types de trait aux dessins techniques industriels, l'Annexe D doit être utilisée. Pour
appliquer les types de trait aux dessins techniques de construction navale, l'Annexe F doit être utilisée.
4.2 Types de base
Les types de traits de base sont donnés dans le Tableau 1.
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ISO 128-2:2020(F)
Tableau 1 — Types de trait de base
N° Representation Description
01 Trait continu
02 Trait interrompu
03 Trait interrompu espacé
04 Trait mixte à un point et un tiret long
Trait mixte à deux points et un
05
tiret long
Trait mixte à trois points et un
06
tiret long
07 Trait pointillé
08 Trait à un tiret long et un tiret court
Trait à un tiret long et deux tirets
09
courts
10 Trait mixte à un point et un tiret
11 Trait mixte à un point et deux tirets
12 Trait mixte à deux points et un tiret
Trait mixte à deux points et deux
13
tirets
14 Trait mixte à trois points et un tiret
Trait mixte à trois points et deux
15
tirets
4.3 Sous-types de traits
Les sous-types de traits sont donnés dans le Tableau 2.
Tableau 2 — Sous-types de trait
Sous-type
Représentation Description
a
n°
.1 Fin
.2 Fort
.3 Extra-fort
a
Structure d'identification du trait
4.4 Variations des types de traits de base
Les traits droits dans le Tableau 1 et les largeurs de trait du Tableau 2 peuvent avoir des variations
telles que montrées dans le Tableau 3.
Tableau 3 — Variations de trait
Représentation Description
Trait continu uniformément ondulé
Trait continu uniformément spiralé
Trait continu uniformément zigzagué
NOTE Le Tableau 3 comprend seulement des variations du type de trait de base n° 01. Des variations des types de traits de
base des n° 02 à 15 sont également possibles, et sont présentées de la même façon.
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ISO 128-2:2020(F)
Tableau 3 (suite)
Représentation Description
Trait continu à main levée / de
forme libre
NOTE Le Tableau 3 comprend seulement des variations du type de trait de base n° 01. Des variations des types de traits de
base des n° 02 à 15 sont également possibles, et sont présentées de la même façon.
4.5 Combinaisons de traits de même longueur
4.5.1 Combinaison de deux traits parallèles entre eux ou plus
Pour des exemples, voir la Figure 1.
Figure 1 — Exemple de traits parallèles entre eux
4.5.2 Combinaison de deux différents types de traits
a) Avec des traits de largeur différente se chevauchant. Voir la Figure 2 a) et b) pour des exemples.
a) Un trait continu et un trait pointillé b) Un trait continu et un trait interrompu
espacé
Figure 2 — Exemple de traits se chevauchant
b) Traits combinés proches. Voir la Figure 3 pour un exemple.
Figure 3 — Deux traits continus fins tangents de part et d’autre d’un trait épais interrompu
4.5.3 Combinaison de deux traits continus parallèles avec des éléments de liaison
régulièrement répétés
Voir la Figure 4 a) et b) pour des exemples.
a) Éléments circulaires pleins b) Éléments trapézoïdaux pleins
Figure 4 — Exemple de traits parallèles avec des éléments de liaison régulièrement répétés
4.5.4 Combinaison d’éléments picturaux géométriques régulièrement répétés en association
avec des traits continus
a) Sans interruption du trait continu. Voir la Figure 5 pour des exemples.
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ISO 128-2:2020(F)
Figure 5 — Sans interruption de trait continu
b) Avec interruption du trait continu. Voir la Figure 6 pour des exemples.
Figure 6 — Avec interruption de trait continu
5 Dimensions des traits
5.1 Largeur des traits
La largeur, d, de tous les types de traits doit être l'une des suivantes en fonction du type et de la taille du
dessin technique. Cette gamme est basée sur un rapport commun 1: √2 (≈ 1:1,4).
0,13 mm; 0,18 mm; 0,25 mm; 0,35 mm; 0,5 mm; 0,7 mm; 1 mm; 1,4 mm; 2 mm
Les largeurs des traits extra-forts, forts et fins sont dans le rapport 4:2:1.
La largeur de tout trait doit être constante tout au long de son tracé.
Voir les Annexes B, D et F pour des informations sur les largeurs de trait se rapportant aux dessins de
construction, dessins industriels et dessins de construction navale.
5.2 Écart dans la largeur de trait
Les largeurs de trait peuvent faire l'objet d'une dérogation par rapport à celles spécifiées en 5.1 pourvu
qu'il soit possible de différencier sans ambiguïté deux traits adjacents avec des largeurs différentes. Si
on utilise des instruments de dessin technique permettant d'obtenir une largeur de trait constante, les
dérogations de largeur de trait entre deux traits ne doivent pas excéder ± 0,1d.
5.3 Configuration des traits
Pour la préparation des dessins techniques, il convient que les longueurs d'éléments de trait soient
conformes avec celles du Tableau 4.
Tableau 4 — Longueurs des éléments de trait
Élément de dessin Type de trait n° Longueur
04 à 07 et
Point ≤ d
10 à 15
NOTE Les longueurs indiquées dans le présent tableau sont valables pour les éléments de
trait dont les extrémités sont semi-circulaires ou à angles droits. Dans le cas d'extrémités
semi-circulaires, les longueurs d'éléments de trait correspondent à la distance parcourue
par un stylo technique tubulaire à encre de Chine, de l'origine à la fin de l’élément de trait.
La longueur totale de cet élément de trait est la somme de la longueur donnée dans le
présent tableau, plus d.
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ISO 128-2:2020(F)
Tableau 4 (suite)
Élément de dessin Type de trait n° Longueur
02 et
Espace 3d
04 à 15
Tiret court 08 et 09 6d
02, 03 et
Tiret 12d
10 à 15
04 à 06,
Tiret long ≈24d
08 et 09
Espace 03 18d
NOTE Les longueurs indiquées dans le présent tableau sont valables pour les éléments de
trait dont les extrémités sont semi-circulaires ou à angles droits. Dans le cas d'extrémités
semi-circulaires, les longueurs d'éléments de trait correspondent à la distance parcourue
par un stylo technique tubulaire à encre de Chine, de l'origine à la fin de l’élément de trait.
La longueur totale de cet élément de trait est la somme de la longueur donnée dans le
présent tableau, plus d.
Des formules pour le calcul de certains des types de traits de base et d’éléments de trait sont données
dans l'Annexe A. Les formules ont pour but de faciliter la préparation de dessins techniques par les
systèmes de conception assistée par ordinateur (CAO).
6 Tracé de traits
6.1 Espacement
Il convient que l'espacement minimal des traits parallèles ne soit pas inférieur à 0,7 mm.
Dans certains cas où des techniques de dessin technique assisté par ordinateur sont utilisées,
l'espacement des traits sur le dessin technique ne représente pas l’espacement réel, par exemple pour la
représentation des filetages. C’est à considérer lors de l'établissement de séries de données, par exemple
pour le fonctionnement des machines-outils.
6.2 Jonctions
6.2.1 Types
Il convient que les types de traits de base, n° 02 à 06 et n° 08 à 15 se croisent sur un tiret pour éviter
toute ambiguité; voir les Figures 7 à 12.
Figure 7 — Traits à un tiret long et un tiret court se croisant comme une croix
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ISO 128-2:2020(F)
Figure 8 — Traits à un tiret se croisant comme une croix
Figure 9 — Traits à un tiret se croisant comme une croix partielle
Figure 10 — Traits à quatre tirets se rencontrant à une intersection
Figure 11 — Traits mixtes à un point et un tiret se croisant comme une croix et traits à un tiret
se rencontrant à des coins
Figure 12 — Traits à un tiret se rencontrant à des coins et à une intersection
8 © ISO 2020 – Tous droits réservés
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ISO 128-2:2020(F)
Il convient que des traits de type de base n° 07 se croisent sur un point pour éviter toute ambiguité, voir
la Figure 13.
Figure 13 — Traits à un point se croisant en un point
6.2.2 Représentation
Les techniques pour appliquer les recommendations du 6.2.1 font commencer les traits à la jonction
(voir Figure 14) ou en utilisant une croix complète, ou partielle, ou un Y (voir Figures 15 et 16).
Figure 14 — Intersection en croix partielle
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ISO 128-2:2020(F)
Figure 15 — Intersection en croix
Figure 16 — Intersection en Y
6.3 Emplacement d'un deuxième trait
Deux méthodes pour présenter deux traits parallèles sont illustrées aux Figures 17 et 18.
Figure 17 — Exemple de traits parallèles avec un trait plein au-dessus d’un trait à un tiret
Figure 18 — Exemple de traits parallèles avec un trait à un tiret au-dessus d’un trait plein
6.4 Hiérarchie des traits chevauchants
Les règles des types de trait chevauchant sont définies à l’Annexe D.
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ISO 128-2:2020(F)
7 Couleurs
Les traits doivent être tracés en noir ou en blanc suivant la couleur de fond. Par défaut, les traits sont
noirs sur un fond blanc. D'autres couleurs normalisées peuvent aussi être utilisées pour des traits
normalisés de dessin technique. Dans ce cas, la signification des couleurs doit être expliquée.
8 Désignation
La désignation des types de traits de base doit comprendre les éléments suivants dans l'ordre donné
avec des espaces entre les éléments:
a) «Trait»;
b) la référence au présent document;
c) le séparateur tiret;
d) le numéro du type de base conformément au Tableau 1;
e) le signe multiplié «×»;
f) la largeur de trait conformément au 5.1;
g) la barre oblique (lorsque la couleur est indiquée);
h) la couleur (lorsqu’elle est indiquée).
EXEMPLES
Désignation d'un trait de type n° 03 (03), d'une largeur de trait de 0,25 mm (0,25):
Trait ISO 128-
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 128-2
ISO/TC 10
Technical product documentation
Secretariat: SIS
(TPD) — General principles of
Voting begins on:
2020-04-06 representation —
Voting terminates on:
Part 2:
2020-06-01
Basic conventions for lines
Documentation technique de produits (TPD) — Principes généraux de
représentation —
Partie 2: Conventions de base pour les traits
ISO/CEN PARALLEL PROCESSING
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 128-2:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020
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ISO/FDIS 128-2:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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ISO/FDIS 128-2:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Types of lines . 3
4.1 General . 3
4.2 Basic types . 3
4.3 Line sub types . 4
4.4 Variations of the basic types of lines . 4
4.5 Combinations of lines with the same length . 4
4.5.1 Arrangement of two or more lines parallel to each other . 4
4.5.2 Arrangement of two different types of lines . 5
4.5.3 Arrangement of two continuous lines parallel to each other with regularly
recurring connecting elements between them . 5
4.5.4 Arrangement of regularly recurring geometric pictorial elements in
association with continuous lines . 5
5 Line dimensions . 6
5.1 Line width . 6
5.2 Deviation in line width . 6
5.3 Configuration of lines . 6
6 Draughting of lines . 7
6.1 Spacing . 7
6.2 Junctions . 7
6.2.1 Types . 7
6.2.2 Representation . 9
6.3 Location of a second line .10
6.4 Hierarchy of overlapping lines .10
7 Colours .11
8 Designation .11
9 Basic conventions and applications for leader lines and reference lines .11
9.1 Presentation of leader lines .11
9.2 Representation of reference lines .14
9.3 Indication of instructions.15
Annex A (informative) Preparation of lines by CAD systems .17
Annex B (normative) Lines on construction technical drawings .30
Annex C (informative) Examples of application on construction technical drawings .33
Annex D (normative) Types of lines and their application on mechanical engineering
technical drawings .39
Annex E (informative) Examples of application on mechanical engineering technical drawings.43
Annex F (normative) Types of lines and their application on shipbuilding technical drawings .56
Annex G (informative) Application examples of the different types of lines on shipbuilding
technical drawings .58
Bibliography .69
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ISO/FDIS 128-2:2020(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 10, Technical product documentation.
This first edition cancels and replaces the following documents:
— ISO 128-20:1996
— ISO 128-21:1997
— ISO 128-22:1999
— ISO 128-23:1999
— ISO 128-24:2014
— ISO 128-25:1999
The main changes to these documents are as follows:
— harmonization of the former parts listed above;
— introduction of the hierarchy of overlapping lines.
A list of all parts in the ISO 128 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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ISO/FDIS 128-2:2020(E)
Introduction
ISO 128-2 contains generally applicable rules for the presentation of lines in all kinds of technical
product documentation.
All figures in this document have been drawn in first-angle projection. It should be understood that
third-angle projection or other methods could have been used equally well without prejudice to the
principles established.
The application of lines within drawings of special technical fields varies considerably. Therefore, rules
of application specific to technical fields are given in Annexes B to G.
Annex A provides information for the calculation of the most important basic types of non-continuous
lines according to types of lines and their line elements.
© ISO 2020 – All rights reserved v
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 128-2:2020(E)
Technical product documentation (TPD) — General
principles of representation —
Part 2:
Basic conventions for lines
1 Scope
This document establishes the types of lines used in technical drawings (e.g. diagrams, plans or
maps), their designations and their configurations, as well as general rules for the draughting of lines.
In addition, this document specifies general rules for the representation of leader and reference lines
and their components as well as for the arrangement of instructions on or at leader lines in technical
documents. Annexes have been provided for specific information on mechanical, construction and
shipbuilding technical drawings.
For the purposes of this document the term “technical drawing” is interpreted in the broadest
possible sense encompassing the total package of documentation specifying the product (workpiece,
subassembly, assembly).
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.
ISO 128-3, Technical drawings — General principles of representation — Part 3: Views, sections and cuts
ISO 128-15, Technical product documentation (TPD) — General principles of presentation — Part 15:
Presentation of shipbuilding drawings
ISO 129-1, Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 1:
General principles
ISO 129-5, Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 5:
Dimensioning of structural metal work
ISO 1101, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form,
orientation, location and run-out
ISO 2203, Technical drawings — Conventional representation of gears
ISO 2538-2, Geometrical product specifications (GPS) — Wedges — Part 2: Dimensioning and tolerancing
ISO 2553, Welding and allied processes — Symbolic representation on drawings — Welded joints
ISO 3040, Geometrical product specifications (GPS) — Dimensioning and tolerancing — Cones
ISO 3766, Construction drawings — Simplified representation of concrete reinforcement
ISO 4463-1, Measurement methods for building — Setting-out and measurement — Part 1: Planning and
organization, measuring procedures, acceptance criteria
ISO 4463-3, Measurement methods for building — Setting-out and measurement — Part 3: Check-lists for
the procurement of surveys and measurement services
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ISO/FDIS 128-2:2020(E)
ISO 5261, Technical drawings — Simplified representation of bars and profile sections
ISO 5455, Technical drawings — Scales
ISO 5456-4, Technical drawings — Projection methods — Part 4: Central projection
ISO 5459, Geometrical product specifications (GPS) — Geometrical tolerancing — Datums and datum systems
ISO 6410-1, Technical drawings — Screw threads and threaded parts — Part 1: General conventions
ISO 6428, Technical drawings — Requirements for microcopying
ISO 7437, Technical drawings — Technical drawings — Construction drawings — General rules for
execution of production drawings for prefabricated structural components
ISO 7519, Technical drawings — Construction drawings — General principles of presentation for general
arrangement and assembly drawings
ISO 8560, Technical drawings — Construction drawings — Representation of modular sizes, lines and grids
ISO 10110-1, Optics and photonics — Preparation of drawings for optical elements and systems —
Part 1: General
ISO 10135, Geometrical product specifications (GPS) — Drawing indications for moulded parts in technical
product documentation (TPD)
ISO 10209, Technical product documentation — Vocabulary — Terms relating to technical drawings,
product definition and related documentation
ISO 11091, Construction drawings — Landscape drawing practice
ISO 12671, Thermal spraying — Thermally sprayed coatings — Symbolic representation on drawings
ISO 15785, Technical drawings — Symbolic presentation and indication of adhesive, fold and pressed joints
ISO 15787, Technical product documentation — Heat-treated ferrous parts — Presentation and indications
ISO 16792, Technical product documentation — Digital product definition data practices
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10209 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
graphical basic element
continuous graphical object with rounded or squared end shape which is represented in any way (e.g.
straight, curved), which has a length and a width
Note 1 to entry: See Figure A.1.
3.2
dot
graphical basic element (3.1) having a length equal to the width, d
Note 1 to entry: See Figure A.2.
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3.3
line
set of one or more graphical basic elements (3.1) having a length of more than the width
Note 1 to entry: See Figure A.3.
3.4
technical drawing
drawing showing a technical installation, process or product with a view to clarifying its structure and
enabling its construction
[SOURCE: ISO 5127:2017, 3.4.7.54, modified — Note 1 to entry removed.]
4 Types of lines
4.1 General
The line type designation consists of a combination of a basic line type and a subtype, depending on the
line width, see 4.2.
For the purposes of this document a line type application number is used to number the application
examples for the line types.
For applying line types to construction technical drawings Annex B shall be applied. For applying line
types to mechanical engineering technical drawings Annex D shall be applied. For applying line types
to ship building technical drawings Annex F shall be applied.
4.2 Basic types
The basic line types are given in Table 1.
Table 1 — Basic line types
No. Representation Description
01 Continuous line
02 Dashed line
03 Dashed spaced line
04 Long-dashed dotted line
05 Long-dashed double-dotted line
06 Long-dashed triplicate-dotted line
07 Dotted line
08 Long-dashed short-dashed line
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Table 1 (continued)
No. Representation Description
Long-dashed double-short-dashed
09
line
10 Dashed dotted line
11 Double-dashed dotted line
12 Dashed double-dotted line
13 Double-dashed double-dotted line
14 Dashed triplicate-dotted line
15 Double-dashed triplicate-dotted line
4.3 Line sub types
The line sub types are given in Table 2.
Table 2 — Line sub types
Sub-type
Representation Description
a
no.
.1 Narrow
.2 Wide
.3 Extra wide
a
Line identification structure
4.4 Variations of the basic types of lines
The straight lines in Table 1 and the line widths of Table 2 can have variations as shown in Table 3.
Table 3 — Line variations
Representation Description
Uniform wavy continuous line
Uniform spiral continuous line
Uniform zigzag continuous line
Freehand / freeform curve continu-
ous line
NOTE Table 3 contains only variations of the basic type of line No. 01. Variations of the basic types of Nos. 02 to 15 are
possible and are presented in the same way.
4.5 Combinations of lines with the same length
4.5.1 Arrangement of two or more lines parallel to each other
For examples see Figure 1.
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Figure 1 — Example of lines parallel to each other
4.5.2 Arrangement of two different types of lines
a) With different line widths superimposed. See Figure 2 a) and b) for examples.
a) A continuous line and a dotted line b) A continuous line and a dashed spaced line
Figure 2 — Example of superimposed lines
b) Arranged next to each other. See Figure 3 for an example.
Figure 3 — Two continuous narrow lines either side of a wide dashed line
4.5.3 Arrangement of two continuous lines parallel to each other with regularly recurring
connecting elements between them
See Figure 4 a) and b) for examples.
a) Filled circular elements b) Filled trapezoidal elements
Figure 4 — Example of lines parallel to each other with regularly recurring connecting
elements
4.5.4 Arrangement of regularly recurring geometric pictorial elements in association with
continuous lines
a) Without interruption of a continuous line. See Figure 5 for examples.
Figure 5 — Without interruption of a continuous line
b) With interruption of a continuous line. See Figure 6 for examples.
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Figure 6 — With interruption of a continuous line
5 Line dimensions
5.1 Line width
The width, d, of all types of lines shall be one of the following depending on the type and size of the
technical drawing. This series is based on a common ratio 1: √2 (≈1:1,4).
0,13 mm; 0,18 mm; 0,25 mm; 0,35 mm; 0,5 mm; 0,7 mm; 1 mm; 1,4 mm; 2 mm.
The widths of extra wide, wide and narrow lines are in the ratio 4:2:1.
The line width of any one line shall be constant throughout the whole line.
See Annexes B, D and F for information on line widths pertaining to construction, mechanical and
shipbuilding technical drawings.
5.2 Deviation in line width
Line widths can deviate from those specified in 5.1 providing that it is possible to differentiate
unambiguously between two adjacent lines with different widths. If technical drawing equipment
which produces constant line width is used, the deviation in line width between two such lines shall not
be greater than ± 0,1d.
5.3 Configuration of lines
For the preparation of technical drawings, the lengths of line elements should conform to those of
Table 4.
Table 4 — Lengths of line elements
Drawing element Line type no. Length
04 to 07 and
Dot ≤ d
10 to 15
02 and
Gap 3d
04 to 15
Short dash 08 and 09 6d
02, 03 and
Dash 12d
10 to 15
04 to 06,
Long dash ≈24d
08 and 09
Space 03 18d
NOTE The lengths shown in this table are valid for line elements with semi-circular and
squared ends. In the case of line elements with semi-circular ends, the length of the line
element corresponds to the distance covered by a technical pen (with a tubular tip and
using India ink) from the origin up to the end of the line element. The total length of such
a line element is the sum of the length shown in this table, plus d.
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ISO/FDIS 128-2:2020(E)
Formulae for the calculation of some of the basic types of lines and line elements are given in Annex A.
The formulae are intended to facilitate the preparation of technical drawings using computer-aided
design (CAD) systems.
6 Draughting of lines
6.1 Spacing
The minimum space between parallel lines should not be less than 0,7 mm.
In certain cases when computer-aided technical drawing techniques are used, the spacing of lines on
the technical drawing does not represent the actual spacing, for example for the representation of
screw threads. This has to be considered when data sets are established, for example for the operation
of machine tools.
6.2 Junctions
6.2.1 Types
The basic types of lines, nos. 02 to 06 and nos. 08 to 15, should meet at a dash to avoid ambiguity; see
Figures 7 to 12.
Figure 7 — Long-dashed short-dashed lines intersecting as a cross
Figure 8 — Dashed lines intersecting as a cross
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Figure 9 — Dashed lines intersecting as a partial cross
Figure 10 — Four dashed lines meeting at an intersection
Figure 11 — Dash dotted lines intersecting as a cross and dashed lines meeting at corners
Figure 12 — Dashed lines meeting at corners and at intersection
Lines of basic type no. 07 should meet at a dot to avoid ambiguity, see Figure 13.
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Figure 13 — Dotted lines intersecting at a dot
6.2.2 Representation
Techniques for applying the recommendations of 6.2.1 are to start the lines at the junction (see
Figure 14) or by using a complete, or partial, cross or Y (see Figures 15 and 16).
Figure 14 — Partial cross intersection
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Figure 15 — Cross intersection
Figure 16 — Y intersection
6.3 Location of a second line
Two different ways of presenting two parallel lines are shown in Figures 17 and 18.
Figure 17 — Example of parallel lines with solid line above dashed line
Figure 18 — Example of parallel lines with dashed line above solid line
6.4 Hierarchy of overlapping lines
The rules of overlapping types of lines are defined in Annex D.
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ISO/FDIS 128-2:2020(E)
7 Colours
Lines shall be drawn in black or white depending on the colour of the background. By default, lines
are black on a white background. Other standardized colours may also be used for technical drawing
standardized lines. In this case, the meaning of the colours shall be explained.
8 Designation
The designation of the basic types of lines shall comprise the following elements in the order given,
with spaces between the elements:
a) “Line”;
b) reference to this document;
c) dash separator
d) the number of the basic type in accordance with Table 1;
e) the multiplication sign “×”;
f) the line width in accordance with 5.1;
g) forward slash (when the colour is indicated)
h) colour (when indicated).
EXAMPLES
Designation of a line of type no. 03 (03), line width 0,25 mm (0,25):
Line ISO 128-2 - 03 × 0,25
Designation of a line of type no. 05 (05), line width 0,13 mm (0,13) and blue in colour:
Line ISO 128-2 - 05 × 0,13/blue
9 Basic conventions and applications for leader lines and reference lines
9.1 Presentation of leader lines
Leader lines are executed as continuous narrow lines (type 01.1) in accordance with this document.
They are drawn at an angle to the relevant representation and/or the frame limiting the drawing sheet,
and not parallel to nearby lines, such as hatching lines. The inclination to the relevant lines shall be >15°.
See Figures 19 to 31.
Leader lines may be drawn with sharp kinks (see Figure 23), and two or more leader lines may
start from the same point (see Figures 20, 23, 25, 26 and 29). They should not cross other leader
lines (see Figure 23) except when the leader line starts from the same point and is colinear (see
Figure 25, 26 and 29), reference lines or indications, such as graphical symbols or dimensional values.
Leader lines shall terminate at the end which touches the features as follows:
— with a closed and filled arrowhead or a closed arrowhead as per ISO 129-1 if the leader line ends
at lines which represent outlines or edges of parts, piping or cables in plans, charts or diagrams;
arrowheads are also drawn at crossing points of these lines with other lines, for example lines of
symmetry (see the examples given in Figures 19 to 25);
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If several parallel lines have to be designated, oblique strokes instead of arrowheads are permitted (see
IEC 61082-1). See the example given in Figure 26.
— with a dot (d = 5 × line width) if the leader line ends on the surface of an object (see the examples
given in Figures 27 to 29);
— without any termination if the leader line ends at another line, for example dimension line or line of
symmetry (see the examples given in Figures 30 and 31).
Figure 19 — Example of a leader line terminating at the edge of a diameter
Figure 20 — Example of leader lines starting at the same point and terminating at part edges
Figure 21 — Example of leader lines terminating at outlines
Figure 22 — Example of leader lines not overlapping cross section lines
Figure 23 — Example of a leader line with a sharp kink.
Figure 24 — Example of a leader line terminating a the crossing point of two lines
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