EN ISO 2553:2019

Welding and allied processes - Symbolic representation on drawings - Welded joints (ISO 2553:2019, Corrected version 2021-09)

This document defines the rules to be applied for symbolic representation of welded joints on technical drawings. This can include information about the geometry, manufacture, quality and testing of the welds. The principles of this document can also be applied to soldered and brazed joints.
It is recognized that there are two different approaches in the global market to designate the arrow side and other side on drawings. In this document:
—          clauses, tables and figures which carry the suffix letter "A" are applicable only to the symbolic representation system based on a dual reference line;
—          clauses, tables and figures which carry the suffix letter "B" are applicable only to the symbolic representation system based on a single reference line;
—          clauses, tables and figures which do not have the suffix letter "A" or "B" are applicable to both systems.
The symbols shown in this document can be combined with other symbols used on technical drawings, for example to show surface finish requirements.
An alternative designation method is presented which can be used to represent welded joints on drawings by specifying essential design information such as weld dimensions, quality level, etc. The joint preparation and welding process(es) are then determined by the production unit in order to meet the specified requirements.
NOTE       Examples given in this document, including dimensions, are illustrative only and are intended to demonstrate the proper application of principles.

Schweißen und verwandte Prozesse - Symbolische Darstellung in Zeichnungen - Schweißverbindungen (ISO 2553:2019, korrigierte Fassung 2021-09)

Dieses Dokument legt die Regeln fest, die in technischen Zeichnungen für die symbolische Darstellung von Schweißnähten anzuwenden sind. Die Symbole können Angaben zur Geometrie, Herstellung, Qualität und Prüfung der Schweißnähte enthalten. Die Grundsätze dieses Dokuments können auch für weich- und hartgelötete Verbindungen verwendet werden.
Es wird die Tatsache berücksichtigt, dass es auf dem Weltmarkt zwei unterschiedliche Methoden gibt, um in Zeichnungen die Pfeilseite und die Gegenseite zu kennzeichnen. In diesem Dokument
- gelten Abschnitte, Tabellen und Bilder mit dem Suffix "A" nur für das System, bei dem in den Symbolen eine doppelte Bezugslinie verwendet wird,
- gelten Abschnitte, Tabellen und Bilder mit dem Suffix "B" nur für das System, bei dem in den Symbolen eine einfache Bezugslinie verwendet wird,
- gelten Abschnitte, Tabellen und Bilder, in denen weder der Suffix "A" noch der Suffix "B" angegeben ist, für beide Darstellungssysteme.
Die in diesem Dokument angegebenen Symbole können mit anderen Symbolen kombiniert werden, die in technischen Zeichnungen angewendet werden, z. B. um Anforderungen an die Oberflächenbeschaffenheit darzustellen.
Ein alternatives Bezeichnungsverfahren wird beschrieben, das angewendet werden kann, um Schweißverbindungen in Zeichnungen durch Festlegung der wichtigsten Konstruktionsangaben, z. B. Nahtmaße, Bewertungsgruppen usw., darzustellen Die Schweißnahtvorbereitung und der/die Schweißprozess(e) werden anschließend von dem Hersteller so festgelegt, dass die festgelegten Anforderungen erfüllt werden.
ANMERKUNG Die in diesem Dokument angegebenen Beispiele, einschließlich der Maße, dienen nur zur Veranschaulichung der korrekten Anwendung der Grundsätze.

Soudage et techniques connexes - Représentations symboliques sur les dessins - Assemblages soudés (ISO 2553:2019, Version corrigée 2021-09)

Le présent document définit les règles à suivre pour représenter symboliquement les joints soudés sur les dessins techniques. Cela peut inclure des informations sur la géométrie, la fabrication, la qualité et les essais des soudures. Les principes du présent document peuvent également être appliqués aux joints soudés et brasés.
Le présent document reconnaît qu'il existe deux méthodes différentes sur le marché mondial pour désigner le côté ligne repère et le côté opposé à la ligne repère sur les dessins. Il convient de noter que :
—          les articles, tableaux et figures qui portent le suffixe «A» sont applicables uniquement au système de représentation symbolique fondé sur un double trait de référence;
—          les articles, tableaux et figures qui portent le suffixe «B» sont applicables uniquement au système de représentation symbolique fondé sur un trait de référence simple;
—          les articles, tableaux et figures qui ne portent ni le suffixe «A» ni le suffixe «B» sont applicables aux deux systèmes.
Les symboles donnés dans le présent document peuvent être combinés à d'autres symboles utilisés sur les dessins techniques, par exemple pour indiquer les exigences de finition de surface.
Une autre méthode de désignation est donnée. Elle peut être utilisée pour représenter des joints soudés sur les dessins en spécifiant les informations essentielles de conception, telles que les dimensions de la soudure, le niveau de qualité, etc. La préparation du joint et le(s) procédé(s) de soudage sont ensuite déterminés par l'unité de production afin de satisfaire aux exigences spécifiées.
NOTE       Les exemples du présent document, y compris les dimensions, ne sont donnés qu'à titre d'illustration et sont destinés à montrer l'application appropriée des principes.

Varjenje in sorodni postopki - Prikazovanje s simboli na risbah - Varjeni spoji (ISO 2553:2019)

Ta dokument določa pravila za prikazovanje varjenih spojev na tehničnih risbah s simboli. To lahko vključuje podatke o geometriji, izdelavi, kakovosti in preskušanju zvarov. Načela tega dokumenta je mogoče uporabiti tudi pri spajkanih in trdo spajkanih spojih.
Na svetovnem trgu obstajata na risbah dva različna pristopa za označevanje na strani s puščico in na drugi strani. V tem dokumentu:
– točke, preglednice in številke s črko »A« se uporabljajo samo za sistem simboličnega predstavljanja, ki temelji na dvojni referenčni vrstici;
– točke, preglednice in številke s črko »B« se uporabljajo samo za sistem simboličnega predstavljanja, ki temelji na enojni referenčni vrstici;
– točke, preglednice in številke brez dodane črke »A« ali »B« se uporabljajo za oba sistema.
Simbole, prikazane v tem dokumentu, je mogoče kombinirati z drugimi simboli, ki se uporabljajo na tehničnih risbah, na primer za prikaz zahtev glede površinske obdelave.
Predstavljena je alternativna metoda označevanja, ki jo je mogoče uporabiti za predstavljanje varjenih spojev na risbah z navedbo bistvenih informacij o konstrukciji, kot so mere vara, raven kakovosti itd. Da so zahteve izpolnjene, poskrbi proizvodna enota, ki določi postopek izdelave in varjenja.
OPOMBA: Primeri v tem dokumentu, vključno z merami, so zgolj ilustrativni in namenjeni
ponazoritvi pravilne uporabe načel.

General Information

• Status: Published
• Publication Date: 16-Apr-2019
• Withdrawal Date: 30-Oct-2019
• ICS: 01.100.20 - Mechanical engineering drawings
• ICS: 25.160.40 - Welded joints and welds
• Technical Committee: CEN/TC 121 - Welding
• Drafting Committee: CEN/TC 121 - Welding
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 17-Apr-2019
• Completion Date: 17-Apr-2019
• Directive: 2014/29/EU - Directive 2014/29/EU of The European Parliament and of the Council of 26 February 2016 on the harmonisation of the laws of the Member States relating to the making available on the market of simple pressure vessels
• Mandate: M/BC/CEN/89/2 - Standardization mandate to CEN concerning supporting standards in the context of pressure vessels
• Ref Project: SIST EN ISO 2553:2019 - Welding and allied processes - Symbolic representation on drawings - Welded joints (ISO 2553:2019)

Relations

• Replaces: EN ISO 2553:2013 - Welding and allied processes - Symbolic representation on drawings - Welded joints (ISO 2553:2013)
• Effective Date: 24-Apr-2019

Overview

EN ISO 2553:2019 (ISO 2553:2019) specifies rules for the symbolic representation of welded joints on technical drawings. It standardizes how weld geometry, manufacture, quality and testing instructions are shown using welding symbols. The principles also apply to soldered and brazed joints. The standard was published in 2019 and replaces earlier versions; it is adopted as EN ISO 2553:2019 for European use.

Key topics and technical requirements

• Welding symbol systems: Defines two global approaches - a dual reference line system (clauses/tables/figures suffixed “A”) and a single reference line system (suffixed “B”); content without suffix applies to both.
• Basic and elementary symbols: Standardized symbols for typical weld types (fillet, butt, plug, spot, seam, stud, overlay, etc.) and rules for combining them.
• Supplementary symbols: Additional notations such as weld‑all‑around, field welds, intermittent welds and surface‑related symbols that can be combined with other drawing symbols (for example, surface finish).
• Reference line, arrow line and tail: Rules for locating welds on drawings, multiple and broken arrow lines, and how to include supplementary instructions in the tail.
• Dimensioning: How to specify cross‑sectional weld dimensions, weld length, intermittent weld spacing, butt weld penetration and joint preparation details.
• Alternative designation method: An option to specify required weld design information (dimensions, quality level, testing) while leaving joint preparation and welding process selection to the production unit.
• Informative annexes: Examples of symbol use, tolerances and transition points for weld types, and alternative ways to designate intermittent welds.

Practical applications

• Creating clear, unambiguous engineering and fabrication drawings for structural, mechanical and piping systems.
• Communicating weld geometry and quality requirements from design to fabrication, inspection and testing.
• Supporting procurement, welding procedure specification (WPS) implementation, and quality assurance activities.
• International projects where consistent welding symbols reduce misinterpretation across suppliers and inspection bodies.

Who should use this standard

• Mechanical and structural designers, CAD draughtspersons and detailers
• Welding engineers and welding coordinators
• Fabrication shops, welders and supervisors
• Quality inspectors and non‑destructive testing (NDT) personnel
• Procurement and contract managers in manufacturing and construction

Related standards and integration

ISO 2553 is commonly used alongside welding procedure and quality standards, welding procedure specifications (WPS), and NDT/inspection codes to provide a complete framework for welding documentation and compliance.

Keywords: ISO 2553, EN ISO 2553:2019, welding symbols, welded joints, technical drawings, weld dimensioning, fillet welds, butt welds, welding notation, weld quality.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2019
Nadomešča:
SIST EN ISO 2553:2014
Varjenje in sorodni postopki - Prikazovanje s simboli na risbah - Varjeni spoji (ISO
2553:2019)
Welding and allied processes - Symbolic representation on drawings - Welded joints
(ISO 2553:2019)
Schweißen und verwandte Prozesse - Symbolische Darstellung in Zeichnungen -
Schweißverbindungen (ISO 2553:2019)
Soudage et techniques connexes - Représentations symboliques sur les dessins - Joints
soudés (ISO 2553:2019)
Ta slovenski standard je istoveten z: EN ISO 2553:2019
ICS:
01.100.20 Konstrukcijske risbe Mechanical engineering
drawings
25.160.40 Varjeni spoji in vari Welded joints and welds
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 2553
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2019
EUROPÄISCHE NORM
ICS 01.100.20; 25.160.40 Supersedes EN ISO 2553:2013
English Version
Welding and allied processes - Symbolic representation on
drawings - Welded joints (ISO 2553:2019)
Soudage et techniques connexes - Représentations Schweißen und verwandte Prozesse - Symbolische
symboliques sur les dessins - Assemblages soudés (ISO Darstellung in Zeichnungen - Schweißverbindungen
2553:2019) (ISO 2553:2019)
This European Standard was approved by CEN on 22 March 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 2553:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 2553:2019) has been prepared by Technical Committee ISO/TC 44 "Welding
and allied processes" in collaboration with Technical Committee CEN/TC 121 “Welding and allied
processes” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2019, and conflicting national standards shall
be withdrawn at the latest by October 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 2553:2013.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 2553:2019 has been approved by CEN as EN ISO 2553:2019 without any modification.

INTERNATIONAL ISO
STANDARD 2553
Fifth edition
2019-03
Welding and allied processes —
Symbolic representation on drawings
— Welded joints
Soudage et techniques connexes — Représentations symboliques sur
les dessins — Assemblages soudés
Reference number
ISO 2553:2019(E)
©
ISO 2019
ISO 2553:2019(E)
© ISO 2019
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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 2553:2019(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Welding symbol . 5
4.1 General . 5
4.2 Basic welding symbol . 5
4.3 Welding symbol systems . 6
4.4 Elementary symbols . 6
4.4.1 General. 6
4.4.2 Combinations of elementary symbols . 9
4.4.3 Double-sided butt welds . 9
4.5 Supplementary symbols .10
4.5.1 General.10
4.5.2 Weld-all-around symbol .13
4.5.3 Welds of the same type made from point to point .14
4.5.4 Field welds .15
4.5.5 Root reinforcement — Butt welds made from one side .15
4.5.6 Welds on flanged butt and flanged corner joints .15
4.6 Arrow line .17
4.6.1 General.17
4.6.2 Multiple arrow lines .17
4.6.3 Broken arrow line .17
4.7 Reference line and weld location .18
4.7.1 Reference line .18
4.7.2 Weld location .18
4.7.3 Multiple reference lines .19
4.8 Tail .20
5 Dimensioning of welds .21
5.1 General .21
5.2 Cross-sectional dimensions .21
5.3 Length dimensions .21
5.3.1 General.21
5.3.2 Intermittent welds.21
5.4 Butt welds .22
5.4.1 Penetration depth .22
5.4.2 Double-sided welds .22
5.4.3 Flanged butt welds .22
5.4.4 Flare bevel and flare-V butt welds .22
5.5 Fillet welds .22
5.5.1 Weld size .22
5.5.2 Deep penetration fillet welds .22
5.6 Plug welds in circular holes .23
5.7 Plug welds in elongated holes (slots) .23
5.8 Spot welds .23
5.9 Seam welds .23
5.10 Edge welds .23
5.11 Stud welds .23
5.12 Overlay welds .23
5.13 Stake welds .24
6 Dimensioning of joint preparations .37
ISO 2553:2019(E)
6.1 General .37
6.2 Root gap .37
6.3 Included angle .37
6.4 Root radius and depth of root faces — U and J butt joints .38
6.5 Depth of joint preparation .38
6.6 Countersink angle for plug welds .39
7 Alternative butt weld symbol with required weld quality .39
7.1 General .39
7.2 Example .40
Annex A (informative) Examples of the use of welding symbols .41
Annex B (informative) Tolerances and transition points for weld types .51
Annex C (informative) Alternative methods for designating intermittent butt and fillet welds .52
Bibliography .55
iv © ISO 2019 – All rights reserved

ISO 2553:2019(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 44, Welding and allied processes,
Subcommittee SC 7, Representation and terms.
Any feedback, question or request for official interpretation related to any aspect of this document
should be directed to the Secretariat of ISO/TC 44/SC 7 via your national standards body. A complete
listing of these bodies can be found at www .iso .org/members .html. Official interpretations, where they
exist, are available from this page: https: //committee .iso .org/sites/tc44/home/interpretation .html.
This fifth edition cancels and replaces the fourth edition (ISO 2553:2013), which has been technically
revised. The main changes compared to the previous edition are as follows:
— editorial corrections especially to align with other ISO/TC 44 standards and terminology;
— figures updated to more accurately reflect welds illustrated;
— plug welds in circular and elongated holes (slots) — clarification especially as it relates to slot welds;
— old Figure 5 is now shown as Table 5 for clarity;
— Clause 6 has been revised to reflect Pacific Rim practices.
ISO 2553:2019(E)
Introduction
The symbols given in this document can be used on technical drawings for welded components. Design-
related specifications, such as type, thickness, and length of weld, weld quality, surface treatment, filler
material and testing specifications, can be indicated directly at the weld by means of the symbols. The
principals of this document can be applied to brazed and soldered joints.
Clarity can be improved by references to collective information in the drawings or references to
additional design-related documents.
Preparation for production can require detailed welding-related planning. The type of representation
described in this document can be used for this purpose and complemented by additional production-
related information (e.g. welding position, welding process, WPS, joint preparation, preheating).
This information is often given in production-related documents, such as work schedules or welding
procedure specifications (WPS).
Technical drawings are intended to clearly and understandably illustrate design-related specifications.
Welding-related drawings are prepared and checked by specially trained personnel (see ISO 14731).
This document recognizes that there are two different approaches in the global market to designate the
arrow side and other side on drawings, and allows for either to be used in isolation, to suit a particular
market need. Application of either approach identifies a welding symbol in accordance with this
1)
document. The approach in accordance with system A is based on ISO 2553:1992 . The approach in
accordance with system B is based upon standards used by Pacific Rim countries.
1)  Withdrawn.
vi © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 2553:2019(E)
Welding and allied processes — Symbolic representation
on drawings — Welded joints
1 Scope
This document defines the rules to be applied for symbolic representation of welded joints on technical
drawings. This can include information about the geometry, manufacture, quality and testing of the
welds. The principles of this document can also be applied to soldered and brazed joints.
It is recognized that there are two different approaches in the global market to designate the arrow side
and other side on drawings. In this document:
— clauses, tables and figures which carry the suffix letter "A" are applicable only to the symbolic
representation system based on a dual reference line;
— clauses, tables and figures which carry the suffix letter "B" are applicable only to the symbolic
representation system based on a single reference line;
— clauses, tables and figures which do not have the suffix letter "A" or "B" are applicable to both
systems.
The symbols shown in this document can be combined with other symbols used on technical drawings,
for example to show surface finish requirements.
An alternative designation method is presented which can be used to represent welded joints on
drawings by specifying essential design information such as weld dimensions, quality level, etc. The
joint preparation and welding process(es) are then determined by the production unit in order to meet
the specified requirements.
NOTE Examples given in this document, including dimensions, are illustrative only and are intended to
demonstrate the proper application of principles.
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 (all parts), Technical drawings — General principles of presentation
ISO 129-1, Technical product documentation (TPD) — Presentation of dimensions and tolerances — Part 1:
General principles
ISO 3098-2, Technical product documentation — Lettering — Part 2: Latin alphabet, numerals and marks
ISO 4063, Welding and allied processes — Nomenclature of processes and reference numbers
ISO/TR 25901 (all parts), Welding and related processes — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TR 25901 (all parts) and the
following apply.
ISO 2553:2019(E)
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
welding symbol
symbol consisting of an arrow line (3.3)and a reference line (3.4) and which can also include elementary
symbols (3.8) and supplementary symbols (3.9), dimensions and/or tail, used on technical drawings
Note 1 to entry: See Clause 4.
3.2
basic welding symbol
symbol consisting of an arrow line (3.3), reference line (3.4) and tail used when the joint is not specified
and only to indicate that a welded joint is to be made
Note 1 to entry: See 4.2.
3.3
arrow line
leader line used to indicate that the joint is to be welded generally drawn at 135° to the reference line (3.4)
Note 1 to entry: See 4.6.
3.4
reference line
part of the welding symbol (3.1) on which the elementary symbol (3.8) is located, generally drawn
parallel to the bottom edge of the drawing
Note 1 to entry: See 4.7.
3.5
tail
V-shaped element added to the end of the continuous reference line (3.4) away from the arrow line (3.3)
Note 1 to entry: See 4.8.
3.6
arrow side
side of the joint to which the arrow line (3.3) is pointing
Note 1 to entry: See 4.7.2.1.
3.7
other side
opposite side of the joint to the arrow side (3.6)
Note 1 to entry: See 4.7.2.1.
3.8
elementary symbol
symbol forming part of the welding symbol (3.1) and drawn on the reference line (3.4) to indicate the
type of weld and joint preparation
Note 1 to entry: See 4.4.
3.9
supplementary symbol
symbol used in conjunction with elementary symbols (3.8) to convey additional information about the joint
Note 1 to entry: See 4.5.
2 © ISO 2019 – All rights reserved

ISO 2553:2019(E)
3.10
complementary information
non-symbolic information, relevant to the welds being made, which may be included in the tail (3.5) of
the welding symbol (3.1)
Note 1 to entry: See 4.8.
3.11
intermittent weld
series of weld elements made at intervals along a joint
[SOURCE: ISO/TR 25901-1:2016, 2.1.6.15]
Note 1 to entry: See 5.3.2.
3.11.1
chain intermittent weld
intermittent weld (3.11) on each side of a joint arranged so that the weld elements lie opposite one
another along the joint
Note 1 to entry: These are usually fillet welds in T-joints and lap joints.
Note 2 to entry: See 5.3.2.2.
[SOURCE: ISO/TR 25901-1:2016, 2.1.6.17, modified — Note 2 to entry has been adapted.]
3.11.2
staggered intermittent weld
intermittent weld (3.11) on each side of a joint arranged so that the weld elements on one side lie opposite
the spaces on the other side (3.7) along the joint
Note 1 to entry: These are usually fillet welds in T-joints and lap joints.
Note 2 to entry: See 5.3.2.3.
[SOURCE: ISO/TR 25901-1:2016, 2.1.6.16, modified — Note 2 to entry has been adapted.]
3.12
offset
distance between the start of welding on one side of a staggered intermittent weld (3.11.2) and the start
of welding on the other side (3.7)
Note 1 to entry: See 5.3.2.3, C.2.3, Table C.1, No. 3, C.3.3 and Table C.2, No. 3.
3.13
back run
DEPRECATED: sealing run
final run deposited on the root side of a fusion weld
[SOURCE: ISO/TR 25901-1:2016, 2.1.8.21]
3.14
backing weld
backing in the form of a weld
3.15
nominal weld length
design length of a weld
Note 1 to entry: Nominal weld length is the length where the weld has its full size.
ISO 2553:2019(E)
3.15.1
nominal length of weld element
nominal length of each element of the weld
Note 1 to entry: Nominal weld length is the length where the weld has its full size.
3.16
nominal throat thickness
a
design value of the height of the largest isosceles triangle that can be inscribed in the section of a
fillet weld
Note 1 to entry: If other nominal throat thicknesses are specified, e.g. fillet welds with unequal leg lengths (see
Table 6, No. 2.3), they need to be clearly specified. In these cases, the symbol a shall not be used.
[SOURCE: ISO/TR 25901-1:2016, 2.1.7.8, modified — The symbol a has been added. Note 1 to entry has
been changed.]
3.17
leg length
z
distance from the actual or projected intersection of the fusion faces and the toe of a fillet weld,
measured across the fusion face
[SOURCE: ISO/TR 25901-1:2016, 2.1.7.5, modified — The symbol z has been added.]
3.18
penetration depth
deposit thickness
DEPRECATED: weld metal thickness
thickness of the weld metal, excluding any reinforcement
[SOURCE: ISO/TR 25901-1:2016, 2.1.7.4]
3.19
deep penetration throat thickness
s
nominal throat thickness (3.16) or effective throat thickness to which a certain amount of fusion
penetration is added
[SOURCE: ISO/TR 25901-1:2016, 2.1.7.9, modified — The symbol s has been added. Note 1 to entry has
been deleted.]
3.20
flare-bevel weld
butt weld between a joint member with a curved surface and another with a planar surface
Note 1 to entry: See Table 6, No. 1.7.
[SOURCE: ISO/TR 25901-1:2016, 2.1.6.18]
3.21
flare-V weld
butt weld between two members with curved surfaces
Note 1 to entry: See Table 6, No. 1.6.
[SOURCE: ISO/TR 25901-1:2016, 2.1.6.19]
4 © ISO 2019 – All rights reserved

ISO 2553:2019(E)
3.22
field weld
weld made outside workshops usually at the place of final installation
[SOURCE: ISO/TR 25901-1:2016, 2.1.8.40]
3.23
stake weld
weld in a T-joint where a laser beam or electron beam is irradiated from a horizontal plate/flange to
vertical plate/web
Note 1 to entry: Vertical plates can be of different forms, such as corrugated panels and folded plates
4 Welding symbol
4.1 General
A reference line and arrow line are required elements. Additional elements may be included to convey
specific information.
It is preferable to show the welding symbol on the same side of the joint that the weld is to be made, i.e.
the arrow side (see 4.7).
The thickness of the arrow lines, reference line, elementary symbols and lettering shall be in accordance
with ISO 128 (all parts) and ISO 3098-2.
In order not to overburden drawings, reference should be made to notes in the drawing or other design-
related documents.
4.2 Basic welding symbol
If joint details are not specified and the only requirement is to indicate that a joint is to be welded,
the basic symbol shown in Figure 1 may be used. In this case, a dual reference line is not required for
system A (see 4.7.1 A) as no details concerning the weld are being conveyed.
The basic welding symbol shall comprise an arrow line, reference line and a tail.
Key
1 arrow line
2 reference line
3 tail
NOTE This symbol is often used to indicate the location of tack welds.
Figure 1 — Basic welding symbol (joint details and type not specified)
ISO 2553:2019(E)
4.3 Welding symbol systems
This document recognizes two different systems, A and B, to designate the arrow side and other side on
drawings.
The symbolic representation in system A is based on a dual reference line consisting of a continuous
line and a dashed line (see 4.7).
The symbolic representation in system B is based on a single reference line (see 4.7).
Clauses, Tables and Figures which carry the suffix "A" or "B" are applicable only to system A or system
B respectively.
Clauses, tables and figures which do not have a suffix are applicable to both systems.
System A and B shall not be mixed and drawings shall clearly indicate which system is used including
units of measurement in accordance with ISO 129-1.
Examples of comprehensive welding symbols showing the location of elements are given in Figure A.1.
4.4 Elementary symbols
4.4.1 General
Elementary symbols, in accordance with Table 1, may be added to the reference line in both systems A
and B to indicate the type of weld to be made.
Elementary symbols form part of the welding symbol and shall be drawn attached to the reference line
generally at the mid-point.
Elementary symbols may be complemented by:
— supplementary symbols (see 4.5 and Table 3);
— dimensions (see Clause 5);
— complementary information.
The orientation of the elementary symbols shall not be changed to that shown in Tables 1 to 3.
Annex B gives guidance on tolerances and transition points for butt welds, edge welds and fillet welds.
If clear illustration by means of symbols is not possible, cross-sections of the welds may be drawn and
dimensioned.
6 © ISO 2019 – All rights reserved

ISO 2553:2019(E)
Table 1 — Elementary symbols
Illustration of weld type
Designation
a
No. (dashed lines show joint preparation Symbol
(weld type)
prior to welding)
b
1 Square butt
b
2 Single-V butt
Single-V butt with
b
broad root face
b
4 Single-bevel butt
Single-bevel butt
b
with broad root face
b
6 Single-U butt
b
7 Single-J butt
8 Flare V
9 Flare bevel
10 Fillet
a
The grey line is not part of the symbol. It indicates the position of the reference line.
b
Butt welds are full penetration unless otherwise indicated by dimensions on the welding symbol or by reference to
other information, for example the WPS.
c
Symbol can also be used for joints with more than 2 members.
ISO 2553:2019(E)
Table 1 (continued)
Illustration of weld type
Designation
a
No. (dashed lines show joint preparation Symbol
(weld type)
prior to welding)
11 Plug
c
12.1 Resistance spot
System A
12.2 Projection
System B
13 Fusion spot
c
14 Resistance seam
15 Fusion seam
16 Stud
Steep-flanked
b
single-V butt
a
The grey line is not part of the symbol. It indicates the position of the reference line.
b
Butt welds are full penetration unless otherwise indicated by dimensions on the welding symbol or by reference to
other information, for example the WPS.
c
Symbol can also be used for joints with more than 2 members.
8 © ISO 2019 – All rights reserved

ISO 2553:2019(E)
Table 1 (continued)
Illustration of weld type
Designation
a
No. (dashed lines show joint preparation Symbol
(weld type)
prior to welding)
Steep-flanked
b
single-bevel butt
c
19 Edge
Flanged butt
20.1
(see also Table 4)
20.2 Flanged corner
21 Overlay
c
22 Stake
a
The grey line is not part of the symbol. It indicates the position of the reference line.
b
Butt welds are full penetration unless otherwise indicated by dimensions on the welding symbol or by reference to
other information, for example the WPS.
c
Symbol can also be used for joints with more than 2 members.
4.4.2 Combinations of elementary symbols
Elementary symbols may be combined as required to represent particular weld configurations.
4.4.3 Double-sided butt welds
The elementary symbols shall be arranged opposite each other on the reference line, including all
required information, when used to represent double-sided butt welds.
In the case of symmetrical double-sided welds with identical symbols and dimensions, the dashed
reference line should be deleted for system A (see Table 2).
An example of an asymmetrical double-sided weld is shown in Table A.3.
ISO 2553:2019(E)
Table 2 — Combined elementary symbols to represent symmetrical double-sided welds
a b
No. Weld type Illustration of weld Symbol
1 Double-V butt
2 Double bevel butt
3 Double-U butt
Double bevel butt
4 (with broad root or
face) and fillet welds
a
Welds may be partial or full penetration which is to be indicated by dimensions on the welding symbol (see Table 6,
No. 1.1 and No. 1.2) or by reference to other information, for example the WPS.
b
The grey line is not part of the symbol. It indicates the position of the reference line.
4.5 Supplementary symbols
4.5.1 General
Additional information concerning the required joint may be provided by the use of supplementary
symbols in accordance with Table 3. Supplementary symbols can, for example, provide information
about the shape of the weld or how the welded joint shall be made.
10 © ISO 2019 – All rights reserved

ISO 2553:2019(E)
Table 3 — Supplementary symbols
a a
No. Designation Symbol Application example Illustration of weld
b
Flush
(flat-finished)
b
2 Convex
b
3 Concave
Toes blended
4 No example
c
smoothly
d
a)  Back run
(made after the sin-
gle-V butt weld)
d
b)  Backing weld
(made before the
single-V butt weld)
Specified root re-
6 inforcement (butt
e
welds)
7a Backing (unspecified)
f
7b Permanent backing
Removable/
7c
f
temporary backing
g
8 Spacer
a
The grey line is not part of the symbol and is included to show the position of symbol on reference line and/or the
arrow line only.
b
Welds that require approximately flush, convex or concave faces without post-weld finishing are specified by use of the
flush, convex or concave contour symbol.
Welds to be finished flush, convex or concave by post-weld finishing or that require a flat but not flush surface require
additional information, e.g. addition of a note in the tail of the welding symbol.
Other symbols in accordance with ISO 1302 may be used to specify surface finish.
c
The toes shall be blended smoothly by welding or finishing. Processing details may be specified in the work
instructions or WPS.
d
The weld run sequence may be indicated on the drawing e.g. by use of multiple reference lines, a note in the tail or by
reference to a weld procedure specification.
e
In system B, also used to designate flanged butt/corner welds (see 4.5.6).
f
M, material to be part of the final welded joint, MR, material to be removed after welding. Further information on the
material can be included in the tail or elsewhere.
g
The material and the dimensions of the consumable insert or spacer can be specified in the tail of the welding symbol
or on the drawing.
h
Explanations of a, z, n, l and (e) are given in Clause 5.
ISO 2553:2019(E)
Table 3 (continued)
a a
No. Designation Symbol Application example Illustration of weld
a)  Joint showing insert in
place
g
9 Consumable insert
b)  Welded joint showing
root bead (insert incorpo-
rated into root). Single V
butt weld not shown
Example A
10 Weld-all-around
Example B
Example C
a
The grey line is not part of the symbol and is included to show the position of symbol on reference line and/or the
arrow line only.
b
Welds that require approximately flush, convex or concave faces without post-weld finishing are specified by use of the
flush, convex or concave contour symbol.
Welds to be finished flush, convex or concave by post-weld finishing or that require a flat but not flush surface require
additional information, e.g. addition of a note in the tail of the welding symbol.
Other symbols in accordance with ISO 1302 may be used to specify surface finish.
c
The toes shall be blended smoothly by welding or finishing. Processing details may be specified in the work
instructions or WPS.
d
The weld run sequence may be indicated on the drawing e.g. by use of multiple reference lines, a note in the tail or by
reference to a weld procedure specification.
e
In system B, also used to designate flanged butt/corner welds (see 4.5.6).
f
M, material to be part of the final welded joint, MR, material to be removed after welding. Further information on the
material can be included in the tail or elsewhere.
g
The material and the dimensions of the consumable insert or spacer can be specified in the tail of the welding symbol
or on the drawing.
h
Explanations of a, z, n, l and (e) are given in Clause 5.
12 © ISO 2019 – All rights reserved

ISO 2553:2019(E)
Table 3 (continued)
a a
No. Designation Symbol Application example Illustration of weld
or
Weld between two
points (see 4.5.3)
or
12 Field weld No example
Staggered intermit-
or
h
tent welds
a
The grey line is not part of the symbol and is included to show the position of symbol on reference line and/or the
arrow line only.
b
Welds that require approximately flush, convex or concave faces without post-weld finishing are specified by use of the
flush, convex or concave contour symbol.
Welds to be finished flush, convex or concave by post-weld finishing or that require a flat but not flush surface require
additional information, e.g. addition of a note in the tail of the welding symbol.
Other symbols in accordance with ISO 1302 may be used to specify surface finish.
c
The toes shall be blended smoothly by welding or finishing. Processing details may be specified in the work
instructions or WPS.
d
The weld run sequence may be indicated on the drawing e.g. by use of multiple reference lines, a note in the tail or by
reference to a weld procedure specification.
e
In system B, also used to designate flanged butt/corner welds (see 4.5.6).
f
M, material to be part of the final welded joint, MR, material to be removed after welding. Further information on the
material can be included in the tail or elsewhere.
g
The material and the dimensions of the consumable insert or spacer can be specified in the tail of the welding symbol
or on the drawing.
h
Explanations of a, z, n, l and (e) are given in Clause 5.
4.5.2 Weld-all-around symbol
The weld-all-around symbol, added at the junction of the arrow and reference lines, may be used to
designate a continuous weld, single or double-sided, extending around a series of connected joints (see
Table 3).
The series of joints may involve different directions and may lie in more than one plane but the weld
shall always be of the same type and dimensions.
ISO 2553:2019(E)
The weld-all-around symbol shall not be used if:
a) the weld does not start and end at the same point, i.e. it is not continuous (see 4.5.3);
b) the weld type changes, for example from a fillet we
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