ISO 128-3:2020
(Main)Technical product documentation (TPD) — General principles of representation — Part 3: Views, sections and cuts
Technical product documentation (TPD) — General principles of representation — Part 3: Views, sections and cuts
This document specifies the general principles for presenting views, sections and cuts applicable to various kinds of technical drawings (e.g. mechanical, electrical, architectural, civil engineering), following the orthographic projection methods specified in ISO 5456-2. Views and sections for shipbuilding technical drawings are discussed in ISO 128-15. Views and sections for 3D models are discussed in ISO 16792. Attention has also been given in this document to the requirements of reproduction, including microcopying in accordance with ISO 6428.
Documentation technique de produits (TPD) — Principes généraux de représentation — Partie 3: Vues, sections et coupes
Le présent document établit les principes généraux de représentation des vues, des sections et des coupes applicables aux différents types de dessins techniques (par exemple génie mécanique, génie électrique, génie architectural, génie civil) suivant les méthodes de projection orthographique, spécifiées dans l'ISO 5456‑2. Les vues et sections pour les dessins techniques de construction navale sont discutées dans l'ISO 128‑15. Les vues et sections pour les modèles 3D sont discutées dans l'ISO 16792. Les spécifications du présent document ont été établies en tenant compte des exigences de reproduction, y compris celles de la micrographie, conformément à l'ISO 6428.
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INTERNATIONAL ISO
STANDARD 128-3
First edition
2020-06
Technical product documentation
(TPD) — General principles of
representation —
Part 3:
Views, sections and cuts
Documentation technique de produits (TPD) — Principes généraux de
représentation —
Partie 3: Vues, sections et coupes
Reference number
ISO 128-3:2020(E)
©
ISO 2020
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ISO 128-3:2020(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
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ISO 128-3:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Basic conventions for views . 2
4.1 General information on views. 2
4.2 Choice of views . 3
4.3 Partial views . 3
4.4 Simplified view of symmetrical parts . . 4
4.5 First angle projection method . 4
4.6 First angle projection method views . 4
4.7 First angle projection graphical symbol . 5
4.8 Third angle projection method . 5
4.9 Third angle projection method views . 5
4.10 Third angle projection graphical symbol . 6
4.11 Other projection methods . 6
4.12 Enlarged features . 6
5 Reference indication for views and enlarged features . 7
5.1 General . 7
5.2 Details of the reference indication . 7
5.3 Examples of indication . 8
6 General information on cuts and sections . 9
6.1 General . 9
6.2 Indication of cuts and sections . 9
6.2.1 Cutting plane . 9
6.2.2 Identification of the cutting plane. 9
6.2.3 Identification of the cuts and sections . 9
6.2.4 Reference indication for cuts and sections .10
6.3 Sections revolved in the relevant view .11
6.4 Cuts/sections of symmetrical parts .12
6.5 Local cuts/sections .12
7 Basic conventions for representing areas on cuts and sections.13
7.1 General information on cuts and sections .13
7.2 Hatching .13
7.3 Shading or toning .14
7.4 Extra-wide continuous outlines .15
7.5 Thin sections .15
7.6 Thin adjacent sections .15
7.7 Specific materials .16
Annex A (normative) Graphical symbols .17
Annex B (informative) Former practices .20
Annex C (normative) Views on mechanical engineering technical drawings .22
Annex D (normative) Sections on mechanical engineering technical drawings .34
Annex E (normative) Projection methods in building technical drawings .39
Annex F (normative) Representation of views, sections and cuts on construction drawings .41
Bibliography .48
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ISO 128-3:2020(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, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/SS
F01, Technical drawings, in accordance with the Agreement on technical cooperation between ISO and
CEN (Vienna Agreement).
This first edition cancels and replaces the following documents:
— ISO 128-30:2001
— ISO 128-33:2018
— ISO 128-34:2001
— ISO 128-40:2001
— ISO 128-44:2001
— ISO 128-50:2001
The main changes to these documents are as follows:
— harmonization of the former parts listed above;
— introduction of reference indication for views and enlarged features;
— use of arc arrow in special position of views moved to a former practice annex.
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 128-3:2020(E)
Introduction
This document contains generally applicable rules for the presentation of views, sections and cuts in all
kinds of technical product documentation. The first angle projection method (formerly referred to as
method E) and the third angle projection method (formerly referred to as method A) are described in
more detail in ISO 5456-2.
All figures in this document, excluding Figure 1, Figure 6 and Figure 7, have been drawn in first-angle
projection method unless other methods are stated. 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 views, sections and cuts within drawings of special technical fields varies
considerably. Therefore, rules of application specific to technical fields are given in Annex A, B and C.
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INTERNATIONAL STANDARD ISO 128-3:2020(E)
Technical product documentation (TPD) — General
principles of representation —
Part 3:
Views, sections and cuts
1 Scope
This document specifies the general principles for presenting views, sections and cuts applicable to
various kinds of technical drawings (e.g. mechanical, electrical, architectural, civil engineering),
following the orthographic projection methods specified in ISO 5456-2. Views and sections for
shipbuilding technical drawings are discussed in ISO 128-15. Views and sections for 3D models are
discussed in ISO 16792.
Attention has also been given in this document to the requirements of reproduction, including
microcopying in accordance with ISO 6428.
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.
1)
ISO 128-2:— , Technical drawings — General principles of presentation — Part 2: Basic conventions for lines
ISO 129-1, Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 1:
General principles
ISO 3098-1, Technical product documentation — Lettering — Part 1: General requirements
ISO 5456-2, Technical drawings — Projection methods — Part 2: Orthographic representations
ISO 6428, Technical drawings — Requirements for microcopying
ISO 10209:2012, Technical product documentation — Vocabulary — Terms relating to technical drawings,
product definition and related documentation
ISO 15519-1, Specification for diagrams for process industry — Part 1: General rules
ISO 81714-1, Design of graphical symbols for use in the technical documentation of products — Part 1:
Basic rules
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/
1) Under preparation. Stage at the time of publication: ISO/FDIS 128-2:2020.
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ISO 128-3:2020(E)
3.1
cut
sectional view
section (3.2) showing, in addition, outlines beyond the cutting plane
Note 1 to entry: While “cut” is generally used in the construction field, “section” is generally used in the
mechanical engineering field, regardless of the definitions in 3.1 or 3.2.
[SOURCE: ISO 10209:2012, 3.11, modified — Note 1 to entry added.]
3.2
section
representation showing only the outlines of an object lying in one or more cutting planes
Note 1 to entry: While “cut” is generally used in the construction field, “section” is generally used in the
mechanical engineering field, regardless of the definitions in 3.1 or 3.2.
[SOURCE: ISO 10209:2012, 3.61, modified — Note 1 to entry added.]
3.3
technical drawing
drawing showing a technical installation, process or product with a view to clarifying its structure and
enabling its construction
Note 1 to entry: For the purpose of this document, the term “technical drawing” is interpreted in the broadest
possible sense, encompassing the total package of documentation specifying the product (work piece,
subassembly, assembly).
[SOURCE: ISO 5127:2017, 3.4.7.54, modified — Note 1 to entry added.]
4 Basic conventions for views
4.1 General information on views
The most informative view of an object shall be used as the principle view, taking into consideration, for
example, its functioning position, position of manufacturing or mounting.
Each view, with the exception of the front or principal figure (view, plan, principal figure), shall be
given clear identification with a capital letter, repeated near the reference arrow needed to indicate the
direction of viewing for the relevant view. Whatever the direction of viewing, the capital letter shall
always be positioned in normal relation to the direction of reading and be indicated either above or on
the right side of the reference arrow.
The reference arrow is defined in Annex A (for the former practice of arc arrow, see Annex B), as is the
lettering height of the identification.
The designated views may be located irrespective of the principal figure. The capital letters identifying
the referenced views shall be placed immediately above the relevant views (see Figure 1).
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ISO 128-3:2020(E)
Figure 1 — Identification of referenced views
For applying views and sections to mechanical engineering technical drawings, Annex C and Annex D
shall apply. For applying projection methods in building technical drawings, Annex E shall apply. For
applying views, sections and cuts to construction technical drawings, Annex F shall apply.
4.2 Choice of views
When views (including cuts and sections) are needed, these shall be selected according to the following
principles:
— limit the number of views (and cuts and sections) to the minimum necessary but sufficient to fully
delineate the object without ambiguity;
— avoid the need for hidden outlines and edges;
— avoid unnecessary repetition of a detail.
Views and sections for 3D models are given in ISO 16792.
4.3 Partial views
Features needing specific illustration, but not meriting a full view, can be illustrated using a partial view
limited by a continuous narrow line with zigzags of type 01.1 according to ISO 128-2:— (see Figure 2).
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ISO 128-3:2020(E)
Figure 2 — Partial view
4.4 Simplified view of symmetrical parts
To save time and space, symmetrical objects can be drawn as a fraction of the whole [see Figure 3 a), b)
and c)].
The line of symmetry is identified at each of its ends by two narrow short parallel lines drawn at right
angles to it [see Figure 3 a), b) and c)]. The graphical symbol for symmetry shall be drawn in accordance
with A.3.
a) Example 1 b) Example 2 c) Example 3
Figure 3 — Examples of simplified views of symmetrical parts
4.5 First angle projection method
The first angle projection method, if used, shall be in accordance with ISO 5456-2.
4.6 First angle projection method views
With reference to the front view, (a), the other views are arranged as follows (see Figure 4):
— the view from above, (b), is placed underneath;
— the view from below, (e), is placed above;
— the view from the left, (c), is placed on the right;
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ISO 128-3:2020(E)
— the view from the right, (d), is placed on the left;
— the view from the rear, (f), may be placed on the left or right, as convenient.
Figure 4 — First angle projection method
4.7 First angle projection graphical symbol
The graphical symbol for the first angle projection method is shown in Figure 5. The proportions and
dimensions of this graphical symbol are specified in ISO 5456-2.
Figure 5 — First angle projection graphical symbol
4.8 Third angle projection method
The third angle projection method, if used, shall be in accordance with ISO 5456-2.
4.9 Third angle projection method views
With reference to the front view, (a), the other views are arranged as follows (see Figure 6):
— the view from above, (b), is placed above;
— the view from below, (e), is placed underneath;
— the view from the left, (c), is placed on the left;
— the view from the right, (d), is placed on the right;
— the view from the rear, (f), may be placed on the left or right, as convenient.
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ISO 128-3:2020(E)
Figure 6 — Third angle projection method
4.10 Third angle projection graphical symbol
The graphical symbol for the third angle projection method is shown in Figure 7. The proportions and
dimensions of this graphical symbol are specified in ISO 5456-2.
Figure 7 — Third angle projection graphical symbol
4.11 Other projection methods
Refer to ISO 5456-2 for information on other projection methods such as mirrored orthographic
projections.
4.12 Enlarged features
When the scale of a technical drawing does not allow all features to be clearly shown or dimensioned,
the unclear features shall be enclosed or encircled by a continuous narrow line (type 01.1), with the area
thus enclosed identified by a capital letter. The features in the area shall also be shown on an enlarged
scale, in a view that is broken with a continuous narrow freehand/free formed curve line (type 01.1).
This shall be accompanied by the identification letter and an indication of the scale beside it between
parentheses, as shown in Figure 8. The rules for lettering height are discussed in Annex A.
Figure 8 — Enlarged features
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ISO 128-3:2020(E)
For unambiguous relation between the circle and the identification letter, a leader line by a continuous
narrow line (type 01.1) and a reference line by a continuous narrow line (type 01.1) should be drawn.
See Figure 9.
Figure 9 — Enlarged features with leader line
5 Reference indication for views and enlarged features
5.1 General
On large-format mechanical technical drawings and technical drawings consisting of more than one
drawing sheet with an extensive amount of views and enlarged features, the readability should be
improved by information (reference indication) after the identification letter of the views.
The purpose is to find the views and the identification letters more easily on the technical drawing or
drawings.
On construction drawings, designations for views and enlarged features can be complemented by
general reference to other drawings containing the views/features.
5.2 Details of the reference indication
The reference indication after the identification letter on the views shall be in accordance with
ISO 15519-1.
Examples with explanation are shown in Figure 10 and Figure 11.
Figure 10 — Details of the reference indication with a single drawing
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ISO 128-3:2020(E)
Figure 11 — Details of the reference indication with multiple drawings
5.3 Examples of indication
Examples of indication are given in Table 1.
Table 1 — Examples of indication
Indication on technical drawing Interpretation
View A is represented at technical drawing
coordinates C10 on the same sheet.
The identification letter and reference arrow on the
main view is represented at technical drawing
coordinates A3 on the same sheet.
Enlarged feature Z is represented at technical drawing
coordinates D5 on sheet 2.
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ISO 128-3:2020(E)
Table 1 (continued)
Indication on technical drawing Interpretation
The indication of the enlarged feature Z is represented
at technical drawing coordinates B3 on sheet 1.
6 General information on cuts and sections
6.1 General
The general rules for the arrangement of views apply equally when drawing cuts and sections.
6.2 Indication of cuts and sections
6.2.1 Cutting plane
The position of the cutting plane(s) shall be indicated by means of a cutting line represented with a
dashed dotted wide line (type 10.2) according to ISO 128-2:—, Annex E and Annex G. A straight cutting
plane shall be drawn (see Figure 12).
If the cutting plane changes its direction, the cutting line should only be drawn at the ends of the cutting
plane, where the cutting plane changes direction (see Figure 13).
If necessary for its legibility, the cutting line may be connected with a long-dashed dotted narrow line
of the type 04.1 according to ISO 128-2:—, Annex D or 04.1 according to ISO 128-2:—, Annex F).
The direction of viewing for the relevant cut and section is indicated by the reference arrows as defined
in Annex A.
The designated cut and section can be located irrespective of the view in which the cutting plane is taken.
Representation of areas on cuts and sections is covered in Clause 7.
6.2.2 Identification of the cutting plane
Each cut and section plane shall be given clear identification with twice the same capital letter, once at
each of the cut and section arrows. This identification should be positioned for reading from the bottom
of the technical drawing.
The 30° or 90° cut and section arrow is defined in A.4, as is the lettering height of the identification.
6.2.3 Identification of the cuts and sections
The identification of the referenced cuts and sections shall be placed immediately above the relevant
representation. (see Figure 12 and 13).
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ISO 128-3:2020(E)
Figure 12 — Example from construction field
Figure 13 — Example from mechanical engineering field
6.2.4 Reference indication for cuts and sections
6.2.4.1 General
On large-format technical drawings and technical drawings consisting of more than one drawing sheet
with an extensive number of cuts and sections, the readability should be improved by information
(reference indication) after the identification letter of the cutting plane and the identification letters of
the referenced cuts and sections.
The purpose is to find the cuts and sections and the identification letters more easily on the technical
drawing or drawings.
The cut and section arrows shall be drawn in accordance with A.5.
6.2.4.2 Details of the reference indication
The reference indication after the identification letter on the views shall be in accordance with
ISO 15519-1.
Examples with explanation are shown in Figure 10 and Figure 11 and Table 2.
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ISO 128-3:2020(E)
Table 2 — Examples of indication
Indication on technical drawing Interpretation
Section A-A is represented at technical drawing
coordinates D5 of the same sheet.
Section B-B is represented at technical drawing
coordinates F4 on drawing sheet 2.
Cutting plane identification A is represented at
technical drawing coordinates C2 of the same sheet.
Cutting plane identification B is represented at
technical drawing coordinates A8 on drawing sheet 1.
Section A-A is represented on technical drawing
number 54934 on sheet 2 at coordinates D5.
Cutting plane identification A is represented on
technical drawing 54932 on sheet 1 at coordinates A8.
6.3 Sections revolved in the relevant view
If unambiguous, a section can be revolved in the relevant view. If this is done, the outline of the section
shall be drawn with continuous narrow lines of the type 01.1 according to ISO 128-2:—. Further
identification is then not necessary [see Figure 14 a) and b)].
NOTE The rotational direction of the section in the view is unknown.
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ISO 128-3:2020(E)
a) Example 1 b) Example 2
Figure 14 — Sections revolved in relevant view
6.4 Cuts/sections of symmetrical parts
Symmetrical parts may be drawn half in view and half in cut/section (see Figure 15).
Figure 15 — Half in cut/section of symmetrical part
6.5 Local cuts/sections
A local cut/section may be drawn if a complete or a half cut/section is unnecessary. The local break shall
be shown by a continuous narrow line (type 01.1) with zigzags or freehand/freeform curve according
to ISO 128-2:—. See Figure 16.
Figure 16 — Local cut/section
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ISO 128-3:2020(E)
7 Basic conventions for repre
...
NORME ISO
INTERNATIONALE 128-3
Première édition
2020-06
Documentation technique de produits
(TPD) — Principes généraux de
représentation —
Partie 3:
Vues, sections et coupes
Technical product documentation (TPD) — General principles of
representation —
Part 3: Views, sections and cuts
Numéro de référence
ISO 128-3:2020(F)
©
ISO 2020
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ISO 128-3:2020(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
Case postale 401 • Ch. de Blandonnet 8
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Tél.: +41 22 749 01 11
E-mail: copyright@iso.org
Web: www.iso.org
Publié en Suisse
ii © ISO 2020 – Tous droits réservés
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ISO 128-3:2020(F)
Sommaire Page
Avant-propos .iv
Introduction .vi
1 Domaine d'application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Conventions de base pour les vues . 2
4.1 Informations générales sur les vues . 2
4.2 Choix des vues . 3
4.3 Vues partielles . 3
4.4 Vue simplifiée de parties symétriques . 4
4.5 Méthode de projection du premier dièdre . 4
4.6 Vues selon la méthode de projection du premier dièdre. 4
4.7 Symbole graphique de la projection du premier dièdre . 5
4.8 Méthode de projection du troisième dièdre . 5
4.9 Vues selon la méthode de projection du troisième dièdre . 5
4.10 Symbole graphique de la projection du troisième dièdre . 6
4.11 Autres méthodes de projection. 6
4.12 Éléments représentés à plus grande échelle . 6
5 Indication de référence pour les vues et éléments représentés à plus grande échelle .7
5.1 Généralités . 7
5.2 Détails de l'indication de référence . 7
5.3 Exemples d'indication . 8
6 Informations générales sur les coupes et les sections . 9
6.1 Généralités . 9
6.2 Indication des coupes et des sections . 9
6.2.1 Plans de coupe . 9
6.2.2 Identification du plan de coupe . 9
6.2.3 Identification des coupes et des sections .10
6.2.4 Indication de référence pour les coupes et les sections .10
6.3 Sections rabattues sur la vue représentée .12
6.4 Coupes/sections de pièces symétriques .12
6.5 Coupes/sections locales .12
7 Conventions de base pour la représentation des surfaces sur des coupes et des sections .13
7.1 Informations générales sur les coupes et les sections .13
7.2 Hachures .13
7.3 Ombrage par trame ou dégradé .15
7.4 Contours en trait continu extra-fort .15
7.5 Sections de faible épaisseur .15
7.6 Sections adjacentes de faible épaisseur .16
7.7 Matériaux spécifiques .16
Annexe A (normative) Symboles graphiques .17
Annexe B (informative) Anciennes pratiques .20
Annexe C (normative) Vues dans des dessins techniques industriels .22
Annexe D (normative) Sections dans des dessins techniques industriels .35
Annexe E (normative) Méthodes de projection dans des dessins techniques de construction .40
Annexe F (normative) Représentation des vues, sections et coupes sur les dessins de
construction .42
Bibliographie .49
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ISO 128-3:2020(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 technique de
produits, en collaboration avec le comité technique CEN/SS F01, Dessins techniques, du Comité européen
de normalisation (CEN) conformément à l’Accord de coopération technique entre l’ISO et le CEN (Accord
de Vienne).
Cette première édition annule et remplace les documents suivants:
— ISO 128-30:2001
— ISO 128-33:2018
— ISO 128-34:2001
— ISO 128-40:2001
— ISO 128-44:2001
— ISO 128-50:2001
Les principales modifications faites à ces documents sont les suivantes:
— harmonisation des parties listées ci-dessus;
— introduction de l'indication de référence pour les vues et les élements représentés à plus grande
échelle;
— utilisation de l'arc fléché dans une position spéciale de vue déplacé dans l'annexe sur les anciennes
pratiques.
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ISO 128-3:2020(F)
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/ fr/ members .html.
© ISO 2020 – Tous droits réservés v
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ISO 128-3:2020(F)
Introduction
Le présent document comprend des règles généralement applicables pour la représentation de vues,
sections et coupes dans toutes sortes de documentations techniques de produits. La méthode de
projection du premier dièdre (qui étaient auparavant la méthode E) et la méthode de projection du
troisième dièdre (qui étaient auparavant la méthode A) sont décrites plus en détail dans l’ISO 5456-2.
Toutes les figures dans le présent document, à l'axception de la Figure 1, de la Figure 6 et de la Figure 7,
ont été dessinées selon la méthode de projection du premier dièdre, sauf si d'autres méthodes sont
précisées. Il convient de comprendre que la projection du troisième dièdre ou d'autres méthodes
auraient pu tout aussi bien être utilisées sans remettre en cause les principes établis.
L’application des vues, sections et coupes dans les dessins de domaines techniques particuliers varie
considérablement. Par conséquent, les règles d’application spécifiques aux champs techniques sont
données dans l’Annexe A, B et C.
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NORME INTERNATIONALE ISO 128-3:2020(F)
Documentation technique de produits (TPD) — Principes
généraux de représentation —
Partie 3:
Vues, sections et coupes
1 Domaine d'application
Le présent document établit les principes généraux de représentation des vues, des sections et des coupes
applicables aux différents types de dessins techniques (par exemple génie mécanique, génie électrique,
génie architectural, génie civil) suivant les méthodes de projection orthographique, spécifiées dans
l'ISO 5456-2. Les vues et sections pour les dessins techniques de construction navale sont discutées
dans l’ISO 128-15. Les vues et sections pour les modèles 3D sont discutées dans l’ISO 16792.
Les spécifications du présent document ont été établies en tenant compte des exigences de reproduction,
y compris celles de la micrographie, conformément à l'ISO 6428.
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).
1)
ISO 128-2:—, Documentation technique de produits — Principes généraux de représentation — Partie 2:
Conventions de base pour les traits
ISO 129-1, Documentation technique de produits (TPD) — Représentation des dimensions et tolérances —
Partie 1: Principes généraux
ISO 3098-1, Documentation technique de produits — Écriture — Partie 1: Exigences générales
ISO 5456-2, Dessins techniques — Méthodes de projection — Partie 2: Représentations orthographiques
ISO 6428, Dessins techniques — Conditions requises pour la micrographie
ISO 10209:2012, Documentation technique de produits — Vocabulaire — Termes relatifs aux dessins
techniques, à la définition de produits et à la documentation associée
ISO 15519-1, Spécifications pour schémas de l’industrie de traitement — Partie 1: Règles générales
ISO 81714-1, Création de symboles graphiques à utiliser dans la documentation technique de produits —
Partie 1: Règles fondamentales
3 Termes et définitions
Pour les besoins du présent document, les termes et les définitions de l’ISO 10209 ainsi que les suivants
s’appliquent.
1) En cours d’élaboration. Stade au moment de la publication: ISO/FDIS 128-2:2020.
© ISO 2020 – Tous droits réservés 1
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ISO 128-3:2020(F)
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
— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/
3.1
coupe
vue en coupe
section (3.2) montrant, en plus, les contours situés en arrière du plan de coupe
Note 1 à l'article: D'une manière générale, et indépendamment des définitions données en 3.1 et 3.2, le terme
“coupe” est utilisé dans le domaine de la construction, alors que le terme “section” est utilisé en construction
mécanique.
[SOURCE: ISO 10209:2012, 3.11, modifié — Note 1 à l'article ajouté.]
3.2
section
représentation montrant exclusivement les contours d'un objet se trouvant dans un ou plusieurs plans
de coupe
Note 1 à l'article: D'une manière générale, et indépendamment des définitions données en 3.1 et 3.2, le terme
“coupe” est utilisé dans le domaine de la construction, alors que le terme “section” est utilisé en construction
mécanique.
[SOURCE: ISO 10209:2012, 3.61, modifié — Note 1 à l'article ajouté.]
3.3
dessin technique
dessin montrant une installation technique, un procédé, ou un produit dans le but de clarifier leur
structure et de permettre leur construction
Note 1 à l'article: 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).
[SOURCE: ISO 5127:2017, 3.4.7.54, modifié — Note 1 à l'article ajouté.]
4 Conventions de base pour les vues
4.1 Informations générales sur les vues
La vue la plus caractéristique de l'objet doit être choisie comme vue de principe, en prenant en
considération, par exemple, sa position d'utilisation, de fabrication ou de montage.
Chaque vue, à l'exception de la vue de la figure de face ou principale (vue, plan, figure principale)
doit avoir une identification claire avec une lettre majuscule, répétée à côté de la flèche de référence
nécessaire pour indiquer la direction d'observation de la vue concernée. Quelle que soit la direction
d'observation, la lettre majuscule doit toujours être positionnée dans le sens perpendiculaire à la
direction de lecture et indiquée au-dessus ou à droite de la flèche de référence.
La flèche repère est définie dans l'Annexe A (pour l’ancienne pratique de l'arc fléché, voir Annexe B), de
même que la hauteur des caractères de l'identifiant.
Les vues désignées peuvent être placées indifféremment par rapport à la figure principale. Les lettres
majuscules identifiant les vues référencées doivent être placées immédiatement au-dessous des vues
correspondantes (voir Figure 1).
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ISO 128-3:2020(F)
Figure 1 — Identification des vues référencées
Pour appliquer les vues et sections aux dessins techniques de génie mécanique, l'Annexe A et l'Annexe D
doivent s'appliquer. Pour appliquer les méthodes de projection aux dessins techniques de la construction,
l'Annexe E doit s'appliquer. Pour appliquer les vues, sections et coupes aux dessins techniques de la
construction, l'Annexe F doit s'appliquer.
4.2 Choix des vues
Lorsque des vues (y compris des coupes et des sections) sont nécessaires, elles doivent être choisies de
manière à:
— limiter le nombre de vues (et de coupes et de sections) au minimum nécessaire, mais suffisant pour
définir complètement l'objet sans ambiguïté;
— éviter la représentation de nombreux contours ou arêtes cachés;
— éviter la répétition inutile de détails.
Les vues et sections pour des modèles 3D sont données dans l’ISO 16792.
4.3 Vues partielles
Les éléments, qui nécessitent une illustration spécifique mais pas une vue entière, peuvent être
représentés par une vue partielle, délimitée par un trait continu fin avec zigzags, type 01.1 selon
l’ISO 128-2:— (voir Figure 2).
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ISO 128-3:2020(F)
Figure 2 — Vue partielle
4.4 Vue simplifiée de parties symétriques
Pour gagner du temps et de l'espace, les pièces symétriques peuvent être représentées par une fraction
de leur vue complète [voir Figure 3 a), b) et c)].
Le trait du plan de symétrie doit être repéré à chacune de ses extrémités par deux petits traits fins
parallèles, perpendiculaires au trait [voir Figure 3 a), b) et c)]. Le symbole graphique de symétrie doit
être réalisé conformément à l'A.3.
a) Exemple 1 b) Exemple 2 c) Exemple 3
Figure 3 — Exemples de vues simplifiées de parties symétriques
4.5 Méthode de projection du premier dièdre
La méthode de projection du premier dièdre, si elle est utilisée, doit être conforme à l'ISO 5456-2.
4.6 Vues selon la méthode de projection du premier dièdre
Par rapport à la vue de face (a), les autres vues sont disposées comme suit (voir Figure 4):
— la vue de dessus (b) est placée au-dessous;
— la vue de dessous (e) est placée au-dessus;
— la vue de gauche (c) est placée à droite;
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ISO 128-3:2020(F)
— la vue de droite (d) est placée à gauche;
— la vue de derrière (f) est placée à droite ou à gauche, selon la nécessité.
Figure 4 — Méthode de projection du premier dièdre
4.7 Symbole graphique de la projection du premier dièdre
Le symbole graphique de la méthode de projection du premier dièdre est représenté à la Figure 5. Les
proportions et les dimensions de ce symbole graphique sont spécifiées dans l'ISO 5456-2.
Figure 5 — Symbole graphique de la projection du premier dièdre
4.8 Méthode de projection du troisième dièdre
La méthode de projection du troisième dièdre, si elle est utilisée, doit être conforme à l'ISO 5456-2.
4.9 Vues selon la méthode de projection du troisième dièdre
Par rapport à la vue de face (a), les autres vues sont disposées comme suit (voir Figure 6):
— la vue de dessus (b) est placée au-dessus;
— la vue de dessous (e) est placée au-dessous;
— la vue de gauche (c) est placée à gauche;
— la vue de droite (d) est placée à droite;
— la vue de derrière (f) est placée à droite ou à gauche, selon la nécessité.
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ISO 128-3:2020(F)
Figure 6 — Méthode de projection du troisième dièdre
4.10 Symbole graphique de la projection du troisième dièdre
Le symbole graphique de la méthode de projection du troisième dièdre est représenté à la Figure 7. Les
proportions et les dimensions de ce symbole graphique sont spécifiées dans l'ISO 5456-2.
Figure 7 — Symbole graphique de la projection du troisième dièdre
4.11 Autres méthodes de projection
Se reporter à l’ISO 5456-2 pour des informations sur d’autres méthodes de projection telles que les
projections orthographiques en miroir.
4.12 Éléments représentés à plus grande échelle
Lorsque l’échelle d'un dessin technique est trop petite pour permettre une représentation et une
cotation claires de tous les éléments, ceux-ci doivent être entourés d’un trait continu fin (type 01.1) et
repérés par une lettre majuscule. Les éléments dans la surface doivent aussi être représentés à plus
grande échelle dans une vue qui est cassée avec un trait continu fin à main levée/trait courbe librement
formé (type 0.1.1). Il doit être accompagné d’une lettre d’identification et d'une identification de l’échelle
choisie donnée entre parenthèses, tel que présenté à la Figure 8. Les règles pour la hauteur des lettres
sont présentés en Annexe A.
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ISO 128-3:2020(F)
Figure 8 — Éléments représentés à plus grande échelle
Pour une relation univoque entre le cercle et la lettre d’identification, il convient de tracer une ligne
repère par un trait continu fin (type 01.1) et un trait de référence par un trait continu fin (type 01.1).
Voir Figure 9.
Figure 9 — Éléments représentés à plus grande échelle avec ligne repère
5 Indication de référence pour les vues et éléments représentés à plus
grande échelle
5.1 Généralités
Dans des dessins techniques mécaniques de grand format et des dessins techniques comprenant plus
d'une feuille de dessin avec un nombre important de vues et d’éléments représentés à plus grande
échelle, il convient que la lisibilité soit améliorée par des informations (indication de référence) après la
lettre d'identification des vues.
L’objet est de trouver les vues et les lettres d'identification plus facilement sur le ou les dessins
techniques.
Sur les dessins de construction, les désignations pour les vues et les éléments représentés à plus grande
échelle peuvent être complétés par une référence générale à d'autres dessins contenant les vues/les
éléments.
5.2 Détails de l'indication de référence
L’indication de référence après la lettre d'identification sur les vues doit être conforme à l'ISO 15519-1.
Des exemples avec une explication sont présentés à la Figure 10 et la Figure 11.
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ISO 128-3:2020(F)
Figure 10 — Détails de l'indication de référence avec un seul dessin
Figure 11 — Détails de l'indication de référence avec plusieurs dessins
5.3 Exemples d'indication
Des exemples d'indication sont donnés dans le Tableau 1.
Tableau 1 — Exemples d'indication
Indication sur le dessin technique Interprétation
La vue A est représentée aux coordonnées C10 du des-
sin technique sur la même feuille.
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ISO 128-3:2020(F)
Tableau 1 (suite)
Indication sur le dessin technique Interprétation
La lettre d'identification et la flèche repère sur la vue
principale sont représentées aux coordonnées A3 du
dessin technique sur la même feuille.
L'élément représenté à plus grande échelle Z est repré-
senté aux coordonnées D5 du dessin technique sur la
feuille 2.
L'indication de l’élément représenté à plus grande
échelle Z est représentée aux coordonnées B3 du des-
sin technique sur la feuille 1.
6 Informations générales sur les coupes et les sections
6.1 Généralités
Les règles générales sur la disposition des vues s'appliquent également aux représentations des coupes
et des sections.
6.2 Indication des coupes et des sections
6.2.1 Plans de coupe
La position du (des) plan(s) de coupe doit être repérée par une ligne de coupe représentée avec un trait
mixte fort à un point et un trait long (type 10.2) selon l’ISO 128-2:—, Annexe E et Annexe G. Un plan de
coupe droit doit être tracé (voir Figure 12).
Si le plan de coupe change de direction, il est recommandé que la ligne de coupe ne soit dessinée qu'aux
extrémités du plan de coupe et à l'endroit où celui-ci change de direction (voir Figure 13).
Si cela est nécessaire pour des raisons de lisibilité, la ligne de coupe connectée avec un trait mixte fin à
un point et un tiret long du type 04.1 selon l’ISO 128-2:—, Annexe D ou 04.1 de l’ISO 128-2:—, Annexe F.
La direction d'observation pour la coupe ou la section concernée est indiquée par les fléches repères
tels que définies dans l'Annexe A.
La coupe ou la section désignée peut être placée indifféremment par rapport à la vue dans laquelle est
pris le plan de coupe.
La représentation des surfaces sur les coupes ou les sections fait l’objet de l'Article 7.
6.2.2 Identification du plan de coupe
Chaque plan de coupe ou de section doit être repéré par une identification claire avec deux fois la même
lettre majuscule, une fois à chacune des fléches de coupe et de section. Il convient que cette identification
soit placée de manière à être lue à partir du bas du dessin technique.
Les fléches de vue et de section à 30° ou à 90° sont définies dans A.4, ainsi que la hauteur des lettres de
l'identification.
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ISO 128-3:2020(F)
6.2.3 Identification des coupes et des sections
L'identification des coupes ou des sections repérées doit se trouver immédiatement au-dessus de la
représentation correspondante (voir Figures 12 et 13).
Figure 12 — Exemple tiré du domaine de la construction
Figure 13 — Exemple tiré du domaine de la construction mécanique
6.2.4 Indication de référence pour les coupes et les sections
6.2.4.1 Généralités
Dans des dessins techniques de grand format et des dessins techniques comprenant plus d'une feuille
de dessin avec un nombre important de coupes et de sections, il convient que la lisibilité soit améliorée
par des informations (indication de référence) après la lettre d'identification du plan de coupe et les
lettres d'identification des coupes ou des sections repérées.
L’objet est de trouver les coupes et les sections et les lettres d'identification plus facilement sur le ou les
dessins techniques.
Les flèc
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 128-3
ISO/TC 10
Technical product documentation
Secretariat: SIS
(TPD) — General principles of
Voting begins on:
2020-03-16 representation —
Voting terminates on:
Part 3:
2020-05-11
Views, sections and cuts
Documentation technique de produits (TPD) — Principes généraux de
représentation —
Partie 3: Vues, sections et coupes
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 128-3:2020(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
---------------------- Page: 1 ----------------------
ISO/FDIS 128-3:2020(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 128-3:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Basic conventions for views . 2
4.1 General information on views. 2
4.2 Choice of views . 3
4.3 Partial views . 3
4.4 Simplified view of symmetrical parts . . 4
4.5 First angle projection method . 4
4.6 First angle projection method views . 4
4.7 First angle projection graphical symbol . 5
4.8 Third angle projection method . 5
4.9 Third angle projection method views . 5
4.10 Third angle projection graphical symbol . 6
4.11 Other projection methods . 6
4.12 Enlarged features . 6
5 Reference indication for views and enlarged features . 7
5.1 General . 7
5.2 Details of the reference indication . 7
5.3 Examples of indication . 8
6 General information on cuts and sections . 9
6.1 General . 9
6.2 Indication of cuts and sections . 9
6.2.1 Cutting plane . 9
6.2.2 Identification of the cutting plane. 9
6.2.3 Identification of the cuts and sections . 9
6.2.4 Reference indication for cuts and sections .10
6.3 Sections revolved in the relevant view .11
6.4 Cuts/sections of symmetrical parts .12
6.5 Local cuts/sections .12
7 Basic conventions for representing areas on cuts and sections.13
7.1 General information on cuts and sections .13
7.2 Hatching .13
7.3 Shading or toning .14
7.4 Extra-wide continuous outlines .15
7.5 Thin sections .15
7.6 Thin adjacent sections .15
7.7 Specific materials .16
Annex A (normative) Graphical symbols .17
Annex B (informative) Former practices .20
Annex C (normative) Views on mechanical engineering technical drawings .22
Annex D (normative) Sections on mechanical engineering technical drawings .34
Annex E (normative) Projection methods in building technical drawings .39
Annex F (normative) Representation of views, sections and cuts on construction drawings .41
Bibliography .48
© ISO 2020 – All rights reserved iii
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ISO/FDIS 128-3:2020(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, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/SS
F01, Technical drawings, in accordance with the Agreement on technical cooperation between ISO and
CEN (Vienna Agreement).
This first edition cancels and replaces the following documents:
— ISO 128-30:2001
— ISO 128-34:2001
— ISO 128-40:2001
— ISO 128-44:2001
— ISO 128-50:2001
— ISO 128-33:2018
— ISO 8048:1984
The main changes to these documents are as follows:
— harmonization of the former parts listed above;
— introduction of reference indication for views and enlarged features;
— use of arc arrow in special position of views moved to a former practice annex.
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 128-3:2020(E)
Introduction
This document contains generally applicable rules for the presentation of views, sections and cuts in all
kinds of technical product documentation. The first angle projection method (formerly referred to as
method E) and the third angle projection method (formerly referred to as method A) are described in
more detail in ISO 5456-2.
All figures in this document, excluding Figure 1, Figure 6 and Figure 7, have been drawn in first-angle
projection method unless other methods are stated. 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 views, sections and cuts within drawings of special technical fields varies
considerably. Therefore, rules of application specific to technical fields are given in Annex A, B and C.
© ISO 2020 – All rights reserved v
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 128-3:2020(E)
Technical product documentation (TPD) — General
principles of representation —
Part 3:
Views, sections and cuts
1 Scope
This document specifies the general principles for presenting views, sections and cuts applicable to
various kinds of technical drawings (e.g. mechanical, electrical, architectural, civil engineering),
following the orthographic projection methods specified in ISO 5456-2. Views and sections for
shipbuilding technical drawings are discussed in ISO 128-15. Views and sections for 3D models are
discussed in ISO 16792.
Attention has also been given in this document to the requirements of reproduction, including
microcopying in accordance with ISO 6428.
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.
1)
ISO 128-2:— , Technical drawings — General principles of presentation — Part 2: Basic conventions for lines
ISO 129-1, Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 1:
General principles
ISO 3098-1, Technical product documentation — Lettering — Part 1: General requirements
ISO 5456-2, Technical drawings — Projection methods — Part 2: Orthographic representations
ISO 6428, Technical drawings — Requirements for microcopying
ISO 10209:2012, Technical product documentation — Vocabulary — Terms relating to technical drawings,
product definition and related documentation
ISO 15519-1, Specification for diagrams for process industry — Part 1: General rules
ISO 81714-1, Design of graphical symbols for use in the technical documentation of products — Part 1:
Basic rules
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:
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1) Under preparation. Stage at the time of publication: ISO/FDIS 128-2:2020.
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3.1
cut
sectional view
section (3.2) showing, in addition, outlines beyond the cutting plane
Note 1 to entry: While “cut” is generally used in the construction field, “section” is generally used in the
mechanical engineering field, regardless of the definitions in 3.1 or 3.2.
[SOURCE: ISO 10209:2012, 3.11, modified — Note 1 to entry added.]
3.2
section
representation showing only the outlines of an object lying in one or more cutting planes
Note 1 to entry: While “cut” is generally used in the construction field, “section” is generally used in the
mechanical engineering field, regardless of the definitions in 3.1 or 3.2.
[SOURCE: ISO 10209:2012, 3.61, modified — Note 1 to entry added.]
3.3
technical drawing
drawing showing a technical installation, process or product with a view to clarifying its structure and
enabling its construction
Note 1 to entry: For the purpose of this document, the term “technical drawing” is interpreted in the broadest
possible sense, encompassing the total package of documentation specifying the product (work piece,
subassembly, assembly).
[SOURCE: ISO 5127:2017, 3.4.7.5.4, modified — Note 1 to entry added.]
4 Basic conventions for views
4.1 General information on views
The most informative view of an object shall be used as the principle view, taking into consideration, for
example, its functioning position, position of manufacturing or mounting.
Each view, with the exception of the front or principal figure (view, plan, principal figure), shall be
given clear identification with a capital letter, repeated near the reference arrow needed to indicate the
direction of viewing for the relevant view. Whatever the direction of viewing, the capital letter shall
always be positioned in normal relation to the direction of reading and be indicated either above or on
the right side of the reference arrow.
The reference arrow is defined in Annex A (for the former practice of arc arrow, see Annex B), as is the
lettering height of the identification.
The designated views may be located irrespective of the principal figure. The capital letters identifying
the referenced views shall be placed immediately above the relevant views (see Figure 1).
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Figure 1 — Identification of referenced views
For applying views and sections to mechanical engineering technical drawings, Annex C and Annex D
shall apply. For applying projection methods in building technical drawings, Annex E shall apply. For
applying views, sections and cuts to construction technical drawings, Annex F shall apply.
4.2 Choice of views
When views (including cuts and sections) are needed, these shall be selected according to the following
principles:
— limit the number of views (and cuts and sections) to the minimum necessary but sufficient to fully
delineate the object without ambiguity;
— avoid the need for hidden outlines and edges;
— avoid unnecessary repetition of a detail.
Views and sections for 3D models are given in ISO 16792.
4.3 Partial views
Features needing specific illustration, but not meriting a full view, can be illustrated using a partial view
limited by a continuous narrow line with zigzags of type 01.1 according to ISO 128-2:— (see Figure 2).
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Figure 2 — Partial view
4.4 Simplified view of symmetrical parts
To save time and space, symmetrical objects can be drawn as a fraction of the whole [see Figure 3 a), b)
and c)].
The line of symmetry is identified at each of its ends by two narrow short parallel lines drawn at right
angles to it [see Figure 3 a), b) and c)]. The graphical symbol for symmetry shall be drawn in accordance
with A.3.
a) Example 1 b) Example 2 c) Example 3
Figure 3 — Examples of simplified views of symmetrical parts
4.5 First angle projection method
The first angle projection method, if used, shall be in accordance with ISO 5456-2.
4.6 First angle projection method views
With reference to the front view, (a), the other views are arranged as follows (see Figure 4):
— the view from above, (b), is placed underneath;
— the view from below, (e), is placed above;
— the view from the left, (c), is placed on the right;
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— the view from the right, (d), is placed on the left;
— the view from the rear, (f), may be placed on the left or right, as convenient.
Figure 4 — First angle projection method
4.7 First angle projection graphical symbol
The graphical symbol for the first angle projection method is shown in Figure 5. The proportions and
dimensions of this graphical symbol are specified in ISO 5456-2.
Figure 5 — First angle projection graphical symbol
4.8 Third angle projection method
The third angle projection method, if used, shall be in accordance with ISO 5456-2.
4.9 Third angle projection method views
With reference to the front view, (a), the other views are arranged as follows (see Figure 6):
— the view from above, (b), is placed above;
— the view from below, (e), is placed underneath;
— the view from the left, (c), is placed on the left;
— the view from the right, (d), is placed on the right;
— the view from the rear, (f), may be placed on the left or right, as convenient.
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Figure 6 — Third angle projection method
4.10 Third angle projection graphical symbol
The graphical symbol for the third angle projection method is shown in Figure 7. The proportions and
dimensions of this graphical symbol are specified in ISO 5456-2.
Figure 7 — Third angle projection graphical symbol
4.11 Other projection methods
Refer to ISO 5456-2 for information on other projection methods such as mirrored orthographic
projections.
4.12 Enlarged features
When the scale of a technical drawing does not allow all features to be clearly shown or dimensioned,
the unclear features shall be enclosed or encircled by a continuous narrow line (type 01.1), with the area
thus enclosed identified by a capital letter. The features in the area shall also be shown on an enlarged
scale, in a view that is broken with a continuous narrow freehand/free formed curve line (type 01.1).
This shall be accompanied by the identification letter and an indication of the scale beside it between
parentheses, as shown in Figure 8. The rules for lettering height are discussed in Annex A.
Figure 8 — Enlarged features
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For unambiguous relation between the circle and the identification letter, a leader line by a continuous
narrow line (type 01.1) and a reference line by a continuous narrow line (type 01.1) should be drawn.
See Figure 9.
Figure 9 — Enlarged features with leader line
5 Reference indication for views and enlarged features
5.1 General
On large-format mechanical technical drawings and technical drawings consisting of more than one
drawing sheet with an extensive amount of views and enlarged features, the readability should be
improved by information (reference indication) after the identification letter of the views.
The purpose is to find the views and the identification letters more easily on the technical drawing or
drawings.
On construction drawings, designations for views and enlarged features can be complemented by
general reference to other drawings containing the views/features.
5.2 Details of the reference indication
The reference indication after the identification letter on the views shall be in accordance with
ISO 15519-1.
Examples with explanation are shown in Figure 10 and Figure 11.
Figure 10 — Details of the reference indication with a single drawing
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Figure 11 — Details of the reference indication with multiple drawings
5.3 Examples of indication
Examples of indication are given in Table 1.
Table 1 — Examples of indication
Indication on technical drawing Interpretation
View A is represented at technical drawing
coordinates C10 on the same sheet.
The identification letter and reference arrow on the
main view is represented at technical drawing
coordinates A3 on the same sheet.
Enlarged feature Z is represented at technical drawing
coordinates D5 on sheet 2.
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Table 1 (continued)
Indication on technical drawing Interpretation
The indication of the enlarged feature Z is represented
at technical drawing coordinates B3 on sheet 1.
6 General information on cuts and sections
6.1 General
The general rules for the arrangement of views apply equally when drawing cuts and sections.
6.2 Indication of cuts and sections
6.2.1 Cutting plane
The position of the cutting plane(s) shall be indicated by means of a cutting line represented with a
dashed dotted wide line (type 10.2) according to ISO 128-2:—, Annex E and Annex G. A straight cutting
plane shall be drawn (see Figure 12).
If the cutting plane changes its direction, the cutting line should only be drawn at the ends of the cutting
plane, where the cutting plane changes direction (see Figure 13).
If necessary for its legibility, the cutting line may be connected with a long-dashed dotted narrow line
of the type 04.1 according to ISO 128-2:—, Annex D or 04.1 according to ISO 128-2:—, Annex F).
The direction of viewing for the relevant cut and section is indicated by the reference arrows as defined
in Annex A.
The designated cut and section can be located irrespective of the view in which the cutting plane is taken.
Representation of areas on cuts and sections is covered in Clause 7.
6.2.2 Identification of the cutting plane
Each cut and section plane shall be given clear identification with twice the same capital letter, once at
each of the cut and section arrows. This identification should be positioned for reading from the bottom
of the technical drawing.
The 30° or 90° cut and section arrow is defined in A.4, as is the lettering height of the identification.
6.2.3 Identification of the cuts and sections
The identification of the referenced cuts and sections shall be placed immediately above the relevant
representation. (see Figure 12 and 13).
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Figure 12 — Example from construction field
Figure 13 — Example from mechanical engineering field
6.2.4 Reference indication for cuts and sections
6.2.4.1 General
On large-format technical drawings and technical drawings consisting of more than one drawing sheet
with an extensive number of cuts and sections, the readability should be improved by information
(reference indication) after the identification letter of the cutting plane and the identification letters of
the referenced cuts and sections.
The purpose is to find the cuts and sections and the identification letters more easily on the technical
drawing or drawings.
The cut and section arrows shall be drawn in accordance with A.5.
6.2.4.2 Details of the reference indication
The reference indication after the identification letter on the views shall be in accordance with
ISO 15519-1.
Examples with explanation are shown in Figure 10 and Figure 11 and Table 2.
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Table 2 — Examples of indication
Indication on technical drawing Interpretation
Section A-A is represented at technical drawing
coordinates D5 of the same sheet.
Section B-B is represented at technical drawing
coordinates F4 on drawing sheet 2.
Cutting plane identification A is represented at
technical drawing coordinates C2 of the same sheet.
Cutting plane identification B is represented at
technical drawing coordinates A8 on drawing sheet 1.
Section A-A is represented on technical drawing
number 54934 on sheet 2 at coordinates D5.
Cutting plane identification A is represented on
technical drawing 54932 on sheet 1 at coordinates A8.
6.3 Sections revolved in the relevant view
If unambiguous, a section can be revolved in the relevant view. If this is done, the outline of the section
shall be drawn with continuous narrow lines of the type 01.1 according to ISO 128-2:—. Further
identification is then not necessary [see Figure 14 a) and b)].
NOTE The rotational direction of the section in the view is unknown.
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