SIST EN ISO 5817:2023

SLOVENSKI STANDARD
SIST EN ISO 5817:2023
01-maj-2005
Nadomešča:
SIST EN ISO 5817:2014
Varjenje - Talilno zvarjeni spoji na jeklu, niklju, titanu in njihovih zlitinah
(izključeno varjenje s snopom) - Stopnje sprejemljivosti nepravilnosti (ISO
5817:2023)
Welding - Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) - Quality levels for imperfections (ISO 5817:2023)
Schweißen - Schmelzschweißverbindungen an Stahl, Nickel, Titan und deren
Legierungen (ohne Strahlschweißen) - Bewertungsgruppen von Unregelmäßigkeiten
(ISO 5817:2023)
Soudage - Assemblages en acier, nickel, titane et leurs alliages soudés par fusion
(soudage par faisceau exclu) - Niveaux de qualité par rapport aux défauts (ISO
5817:2023)
Ta slovenski standard je istoveten z: EN ISO 5817:2023
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
SIST EN ISO 5817:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 5817:2023

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SIST EN ISO 5817:2023


EN ISO 5817
EUROPEAN STANDARD

NORME EUROPÉENNE

March 2023
EUROPÄISCHE NORM
ICS 25.160.40 Supersedes EN ISO 5817:2014
English Version

Welding - Fusion-welded joints in steel, nickel, titanium
and their alloys (beam welding excluded) - Quality levels
for imperfections (ISO 5817:2023)
Soudage - Assemblages en acier, nickel, titane et leurs Schweißen - Schmelzschweißverbindungen an Stahl,
alliages soudés par fusion (soudage par faisceau exclu) Nickel, Titan und deren Legierungen (ohne
- Niveaux de qualité par rapport aux défauts (ISO Strahlschweißen) - Bewertungsgruppen von
5817:2023) Unregelmäßigkeiten (ISO 5817:2023)
This European Standard was approved by CEN on 10 February 2023.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye 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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 5817:2023 E
worldwide for CEN national Members.

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SIST EN ISO 5817:2023
EN ISO 5817:2023 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 5817:2023
EN ISO 5817:2023 (E)
European foreword
This document (EN ISO 5817:2023) 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 September 2023, and conflicting national standards
shall be withdrawn at the latest by September 2023.
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 5817:2014.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 5817:2023 has been approved by CEN as EN ISO 5817:2023 without any modification.

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SIST EN ISO 5817:2023

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SIST EN ISO 5817:2023
INTERNATIONAL ISO
STANDARD 5817
Fourth edition
2023-02
Welding — Fusion-welded joints in
steel, nickel, titanium and their alloys
(beam welding excluded) — Quality
levels for imperfections
Soudage — Assemblages en acier, nickel, titane et leurs alliages
soudés par fusion (soudage par faisceau exclu) — Niveaux de qualité
par rapport aux défauts
Reference number
ISO 5817:2023(E)
© ISO 2023

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SIST EN ISO 5817:2023
ISO 5817:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
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SIST EN ISO 5817:2023
ISO 5817:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 3
5 A ssessment of imperfections .4
Annex A (informative) Examples of determination of percentage (%) porosity.21
Annex B (informative) Additional criteria for welds in steel subject to fatigue .23
Bibliography .26
iii
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SIST EN ISO 5817:2023
ISO 5817:2023(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 10, Quality management in the field of welding, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 121, Welding and allied processes,
in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 5817:2014), which has been technically
revised.
The main changes are as follows:
— editorial updates;
— actual throat thickness a used in Table 1, nos 1.3, 1.4, 1.16 and 3.2;
A,
— figures for Table 1, nos 1.4, 1.5, 1.6, 1.11, 1.14, 1.16, 1.19, 2.12, 2.13 and 4.1 changed or added;
— Table 1, no. 4.1: exclusion of several imperfections and change of acceptance criteria;
— Former Annex B deleted.
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. Official
interpretations of ISO/TC 44 documents, where they exist, are available from this page:
https://committee.iso.org/sites/tc44/home/interpretation.html.
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SIST EN ISO 5817:2023
ISO 5817:2023(E)
Introduction
This document is intended to be used as a reference in the drafting of application codes and/or other
application standards. It contains a simplified selection of fusion weld imperfections based on the
designations given in ISO 6520-1.
Some of the imperfections described in ISO 6520-1 have been used directly and some have been grouped
together. The basic numerical referencing system from ISO 6520-1 has been used.
The purpose of this document is to specify dimensions of typical imperfections which might be
expected in normal fabrication. It may be used within a quality system for the production of welded
joints. It provides three sets of dimensional values from which a selection can be made for a particular
application. The quality level necessary in each case should be specified by the application standard or
the responsible designer in conjunction with the manufacturer, user and/or other parties concerned.
The quality level shall be prescribed before the start of production, preferably at the enquiry or order
stage. For special purposes, additional details may be prescribed. If the welds will be subsequently
coated with a protective coating, lining or paint, the welds might require more thorough post weld
treatment or surface finishing to achieve the requirements in ISO 8501-3.
The quality levels given in this document provide basic reference data and are not specifically related
to any particular application. They refer to types of welded joint in fabrication and not to the complete
product or component itself. It is possible, therefore, that different quality levels are applied to
individual welded joints in the same product or component.
The main part of the document takes no account for fitness or design for purpose. Annex B gives a
possibility to address design for purpose for fatigue applications.
It would normally be expected that for a particular welded joint the dimensional limits for imperfections
can all be covered by specifying one quality level. In some cases, it can be necessary to specify different
quality levels for different imperfections in the same welded joint. The choice of quality level for any
application should take account of design considerations, subsequent processing (e.g. surfacing), mode
of stressing (e.g. static, dynamic), service conditions (e.g. temperature, environment) and consequences
of failure. Economic factors are also important and should include not only the cost of welding but also
of inspection, testing and repair.
Although this document includes types of imperfection relevant to the fusion welding processes listed
in Clause 1, only those which are applicable to the process and application in question need to be
considered.
Imperfections are quoted in terms of their actual dimensions, and their detection and evaluation
can require the use of one or more methods of non-destructive testing. The detection and sizing of
imperfections is dependent on the testing methods and the extent of testing specified in the application
standard or contract.
This document does not address the methods used for the detection of imperfections. However,
ISO 17635 contains a correlation between the quality level and acceptance level for different NDT
methods.
This document is directly applicable to visual testing of welds and does not include details of
recommended methods of detection or sizing by non-destructive means. It should be considered that
there are difficulties in using these limits to establish appropriate criteria applicable to non-destructive
testing methods, such as ultrasonic testing (UT), radiographic testing (RT), eddy current testing (ET),
penetrant testing (PT) and magnetic particle testing (MT) and that these will possibly need to be
supplemented by requirements for inspection, examining and testing.
The values given for imperfections are for welds produced using normal welding practice. Requirements
for smaller (more stringent) values as stated in quality level B may include additional manufacturing
processes, e.g. grinding, TIG dressing.
Annex B gives additional requirements for welds subject to fatigue.
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SIST EN ISO 5817:2023

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SIST EN ISO 5817:2023
INTERNATIONAL STANDARD ISO 5817:2023(E)
Welding — Fusion-welded joints in steel, nickel, titanium
and their alloys (beam welding excluded) — Quality levels
for imperfections
1 Scope
This document specifies quality levels of imperfections in fusion-welded joints (except for beam
welding) in all types of steel, nickel, titanium and their alloys. It applies to material thickness ≥ 0,5 mm.
It covers fully penetrated butt welds and all fillet welds. Its principles can also be applied to partial-
penetration butt welds.
Quality levels for beam-welded joints in steel are presented in ISO 13919-1.
Three quality levels are given in order to permit application to a wide range of welded fabrication. They
are designated by symbols B, C and D. Quality level B corresponds to the highest requirement on the
finished weld.
Several types of loads are considered, e.g. static load, thermal load, corrosion load, pressure load.
Additional guidance on fatigue loads is given in Annex B.
The quality levels refer to production and good workmanship.
This document is applicable to:
a) non-alloy and alloy steels;
b) nickel and nickel alloys;
c) titanium and titanium alloys;
d) manual, mechanized and automatic welding;
e) all welding positions;
f) all types of welds, e.g. butt welds, fillet welds and branch connections;
g) the following welding processes and their sub-processes, as defined in ISO 4063:
— 11 metal arc welding without gas protection;
— 12 submerged arc welding;
— 13 gas-shielded metal arc welding;
— 14 gas-shielded arc welding with non-consumable tungsten electrode;
— 15 plasma arc welding;
— 31 oxyfuel gas welding (for steel only).
Metallurgical aspects, such as grain size and hardness, are not covered by this document.
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.
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SIST EN ISO 5817:2023
ISO 5817:2023(E)
ISO 25901 (all parts), Welding and allied processes — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in the ISO 25901 series and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
quality level
description of the quality of a weld on the basis of type, size and amount of selected imperfections
3.2
short imperfection
imperfection whose total length is not greater than 25 mm in the
100 mm of the weld which contains the greatest number of imperfections
3.3
short imperfection
< welds less than 100 mm long> imperfection whose total length is not greater than 25 % of the length
of the weld
3.4
systematic imperfection
imperfection that is repeatedly distributed in the weld over the weld length to be tested, the size of a
single imperfection being within the specified limits
3.5
projected area
area where imperfections distributed along the volume of the weld under consideration are imaged
two-dimensionally
Note 1 to entry: In contrast to the cross-sectional area, the occurrence of imperfections is dependent on the weld
thickness when exposed radiographically (see Figure 1).
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SIST EN ISO 5817:2023
ISO 5817:2023(E)
Key
1 direction of rays 3 sixfold thickness 5 twofold thickness
2 four pores per volume unit 4 threefold thickness 6 onefold thickness
Figure 1 — Radiographic films of specimens with identical occurrence of pores per volume unit
3.6
cross-sectional area
area to be considered after fracture or sectioning
3.7
smooth transition
even surface with no irregularities or sharpness at the transition between the weld bead and the parent
material and/or the adjacent welding bead(s)
3.8
fatigue class
FATx
classification reference to S-N curve
6
Note 1 to entry: x is the stress range in MPa at 2 · 10 cycles.
Note 2 to entry: Fatigue properties are described by S-N curves (stress-number of cycle-curves).
Note 3 to entry: See Annex B.
4 Symbols
a nominal throat thickness of the fillet weld (see also ISO 2553)
a actual throat thickness (throat thickness of the finalized weld) (see ISO/TR 25901-1)
A
A area surrounding the gas pores
b width of weld reinforcement
d diameter of gas pore
d diameter of area surrounding the gas pores
A
h height or width of imperfection
3
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SIST EN ISO 5817:2023
ISO 5817:2023(E)
i penetration in fillet welds
l length of imperfection in longitudinal direction of the weld
l length of projected or cross-sectional area
p
r radius of weld toe
s nominal butt weld thickness
t wall or plate thickness (nominal size)
w width of the weld or width or height of the cross-sectional area
p
z leg length of a fillet weld (see also ISO 2553)
α angle of weld toe
β angle of angular misalignment
5 Assessment of imp erfections
Limits for imperfections in accordance with ISO 6520-1 are given in Table 1.
If, for the detection of imperfections, macro-examination is used, only those imperfections shall be
considered which can be detected with a maximum of tenfold magnification. Excluded from this are
micro lack of fusion (see Table 1, 1.5) and microcracks (see Table 1, 2.2).
Systematic imperfections are only permitted in quality level D, provided the other requirements of
Table 1 are fulfilled.
A welded joint should usually be assessed separately for each individual type of imperfection (see
Table 1, 1.1 to 3.2).
Different types of imperfection occurring at any cross-section of the joint need special consideration
(see multiple imperfections in Table 1, 4.1).
The limits for multiple imperfections (see Table 1) are only applicable for cases where the requirements
for a single imperfection are not exceeded.
Any two adjacent imperfections separated by a distance smaller than the major dimension of the
smaller imperfection shall be considered as a single imperfection.
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SIST EN ISO 5817:2023
ISO 5817:2023(E)
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Table 1 — Limits for imperfections
Reference Limits for imperfections for quality levels
t
Imperfection
No. to Remarks
designation
D C B
mm
ISO 6520-1
1 Surface imperfections
1.1 100 Crack ≥ 0,5 Not permitted Not permitted Not permitted
1.2 104 Crater crack ≥ 0,5 Not permitted Not permitted Not permitted
1.3 2017 Surface pore On the weld face or the weld root 0,5 to 3 Butt welds Not permitted Not permitted
d ≤ 0,3 s
Maximum dimension of a single pore
fillet welds
d ≤ 0,3 a
A
> 3 Butt welds butt welds d ≤ 0,2 s, Not permitted
d ≤ 0,3 s, but max. but max. 2 mm
3 mm
fillet welds
fillet welds d ≤ 0,2 a , but max.
A
d ≤ 0,3 a , but 2 mm
A
max. 3 mm
1.4 2025 End crater pipe — butt welds 0,5 to 3 Butt welds Not permitted Not permitted
h ≤ 0,2 s
d ≤ 0,3 s
fillet welds
h ≤ 0,2 a ,
A
d ≤ 0,3 a
A
— fillet welds > 3 Butt welds Butt welds h ≤ 0,1 s, Not permitted
h ≤ 0,2 s, but max. but max. 1 mm
2 mm
d ≤ 0,2 s, but max.
d ≤ 0,3 s, but max. 2 mm
3 mm
fillet welds
fillet welds h ≤ 0,1 a , but max.
A
h ≤ 0,2 a , but 1 mm
A
max. 2 mm
d ≤ 0,2 a , but max.
A
d ≤ 0,3 a , but 2 mm
A
max. 3 mm
1.5 401 Lack of fusion (in- ≥ 0,5 Not permitted Not permitted Not permitted
complete fusion)
4014 Micro lack of Only detectable by micro examination (≥50 × ) ≥ 0,5 Permitted Permitted Not permitted
fusion

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SIST EN ISO 5817:2023
ISO 5817:2023(E)
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Table 1 (continued)
Reference Limits for imperfections for quality levels
t
Imperfection
No. to Remarks
designation
mm D C B
ISO 6520-1
1.6 4021 Incomplete root Only for single side butt welds (full penetration) ≥ 0,5 Short Not permitted Not permitted
penetration imperfections:
h ≤ 0,2 t but max.
2 mm
1.7 5011 Continuous un- Smooth transition is required. 0,5 to 3 Short Short Not permitted
dercut This is not regarded as a systematic imperfection. imperfections: imperfections:
h ≤ 0,2 t h ≤ 0,1 t
5012 Intermittent > 3 h ≤ 0,2 t, but max. h ≤ 0,1 t, but max. h ≤ 0,05 t, but max.
undercut (short 1 mm 0,5 mm 0,5 mm
imperfection)
1.8 5013 Shrinkage Smooth transition is required. 0,5 to 3 Short Short Not permitted
grooves imperfections: imperfections:

h ≤ 0,1 t + 0,2 mm h ≤ 0,1 t
  > 3 Short Short Short
imperfections: imperfections: imperfections:
h ≤ 0,2 t, but max. h ≤ 0,1 t, but h ≤ 0,05 t, but max.
2 mm max.1 mm 0,5 mm

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SIST EN ISO 5817:2023
ISO 5817:2023(E)
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Table 1 (continued)
Reference Limits for imperfections for quality levels
t
Imperfection
No. to Remarks
designation
mm D C B
ISO 6520-1
1.9 502 Excess weld Smooth transition is required between the capping run(s) and the plate ≥ 0,5 h ≤ 0,25 b + 1 mm, h ≤ 0,15 b + 1 mm, h ≤ 0,1 b + 1 mm,
metal (butt weld) surface and/or the adjacent welding bead(s) but max. 10 mm but max. 7 mm but max. 5 mm
1.10 503 Excessive convex- Smooth transition is required between the cap of the weld and the plate ≥ 0,5 h ≤ 0,25 b + 1 mm, h ≤ 0,15 b + 1 mm, h ≤ 0,1 b + 1 mm,
ity (fillet weld) surface and/or the adjacent welding bead(s) but max. 5 mm but max. 4 mm but max. 3 mm
1.11 504 Excessive pene- 0,5 to 3 h ≤ 0,6 b + 1 mm h ≤ 0,3 b + 1 mm h ≤ 0,1 b + 1 mm
tration
> 3 h ≤ 1,0 b + 1 mm, h ≤ 0,45 b + 1 mm, h ≤ 0,2 b + 1 mm,
but max. 5 mm but max. 4 mm but max. 3 mm

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SIST EN ISO 5817:2023
ISO 5817:2023(E)
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Table 1 (continued)
Reference Limits for imperfections for quality levels
t
Imperfection
No. to Remarks
designation
mm D C B
ISO 6520-1
1.12 505 Incorrect weld — butt welds ≥ 0,5 α ≥ 90° α ≥ 110° α ≥ 150°
toe

Not applicable for the root
— fillet welds ≥ 0,5 α ≥ 90° α ≥ 100° α ≥ 110°

α ≥ α and α ≥ α
1 2
1.13 506 Overlap ≥ 0,5 h ≤ 0,2 b Not permitted Not permitted
1.14 509 Sagging Smooth transition is required 0,5 to 3 Short Short Not permitted
imperfections: imperfections:
h ≤ 0,25 t h ≤ 0,1 t
> 3 Short Short Short
imperfections: imperfections: imperfections:
h ≤ 0,25 t, but h ≤ 0,1 t, but max. h ≤ 0,05 t, but max.
max. 2 mm 1 mm 0,5 mm

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SIST EN ISO 5817:2023
ISO 5817:2023(E)
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Table 1 (continued)
Reference Limits for imperfections for quality levels
t
Imperfection
No. to Remarks
designation
mm D C B
ISO 6520-1
511 Incompletely
filled groove
1.15 510 Burn through — ≥ 0,5 Not permitted Not permitted Not permitted
1.16 512 Excessive asym- In cases where an asymmetric fillet weld has not been prescribed. ≥ 0,5 h ≤ 0,2 a + 2 mm h ≤ 0,15 a + 2 mm h ≤ 0,15 a + 1,5 mm
A A A
metry of fillet
weld (excessive
unequal leg
length)
h = |Z − Z |
1 2

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SIST EN ISO 5817:2023
ISO 5817:2023(E)
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Table 1 (continued)
Reference Limits for imperfections for quality levels
t
Imperfection
No. to Remarks
designation
mm D C B
ISO 6520-1
1.17 515 Root concavity Smooth transition is required. 0,5 to 3 h ≤ 0,1 t + 0,2 mm Short Not permitted
imperfections:
h ≤ 0,1 t
  > 3 Short Short Short
imperfections: imperfections: imperfections:
h ≤ 0,2 t, but max. h ≤ 0,1 t, but max. h ≤ 0,05 t, but max.
2 mm 1 mm 0,5 mm
1.18 516 Root porosity Spongy formation at the root of a weld due to bubbling of the weld metal at ≥ 0,5 Acceptance Not permitted Not permitted
the moment of solidification (e.g. lack of gas backing) depends on
application, e.g.
material, corro-
sion protection
1.19 517 Poor restart ≥ 0,5 Permitted Not permitted Not permitted
The limit depends
on the type of im-
perfection which
occurred due to
the restart

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SIST EN ISO 5817:2023
ISO 5817:2023(E)
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Table 1 (continued)
Reference Limits for imperfections for quality levels
t
Imperfection
No. to Remarks
designation
mm D C B
ISO 6520-1
1.20 5213 Insufficient Not applicable to processes with proof of greater depth of penetration 0,5 to 3 Short Short Not permitted
throat thickness imperfections: imperfections:
h ≤ 0,1 a + 0,2 mm h ≤ 0,2 mm
  > 3 Short Short Not permitted
imperfections: imperfections:
h ≤ 0,1 a + 0,3 mm, h ≤ 0,1 a + 0,3 mm,
but max. 2 mm but max. 1 mm
1.21 5214 Excessive throat The actual throat thickness of the fillet weld is too large. ≥ 0,5 Permitted h ≤ 0,2 a + 1 mm, h ≤ 0,15 a + 1 mm,
thickness but max. 4 mm but max. 3 mm

1.22 601 Stray arc — ≥ 0,5 Permitted, if the Not permitted Not permitted
properties of the
parent metal are
not affected
1.23 602 Spatter — ≥ 0,5 Acceptance Acceptance Acceptance
depends on depends on depends on ap-
application, e.g. application, e.g. plication, e.g. ma-
material, corro- materi
...

SLOVENSKI STANDARD
oSIST prEN ISO 5817:2021
01-september-2021
Varjenje - Talilno zvarjeni spoji na jeklu, niklju, titanu in njihovih zlitinah (izključeno
varjenje s snopom) - Stopnje sprejemljivosti nepopolnosti (ISO/DIS 5817:2021)
Welding - Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) - Quality levels for imperfections (ISO/DIS 5817:2021)
Schweißen - Schmelzschweißverbindungen an Stahl, Nickel, Titan und deren
Legierungen (ohne Strahlschweißen) - Bewertungsgruppen von Unregelmäßigkeiten
(ISO/DIS 5817:2021)
Soudage - Assemblages en acier, nickel, titane et leurs alliages soudés par fusion
(soudage par faisceau exclu) - Niveaux de qualité par rapport aux défauts (ISO/DIS
5817:2021)
Ta slovenski standard je istoveten z: prEN ISO 5817
ICS:
25.160.40 Varjeni spoji in vari Welded joints and welds
oSIST prEN ISO 5817:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 5817:2021

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oSIST prEN ISO 5817:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5817
ISO/TC 44/SC 10 Secretariat: DIN
Voting begins on: Voting terminates on:
2021-08-05 2021-10-28
Welding — Fusion-welded joints in steel, nickel, titanium
and their alloys (beam welding excluded) — Quality levels
for imperfections
Soudage — Assemblages en acier, nickel, titane et leurs alliages soudés par fusion (soudage par faisceau
exclu) — Niveaux de qualité par rapport aux défauts
ICS: 25.160.40
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 5817:2021(E)
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 SUPPORTING DOCUMENTATION. ISO 2021

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oSIST prEN ISO 5817:2021
ISO/DIS 5817:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

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oSIST prEN ISO 5817:2021
ISO/DIS 5817:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 3
5 Assessment of imperfections . 4
Annex A (informative) Examples of determination of percentage (%) porosity .20
Annex B (informative) Additional information and guidelines for use of this document .22
Annex C (informative) Additional requirements for welds in steel subject to fatigue .23
Bibliography .26
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oSIST prEN ISO 5817:2021
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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 10, Quality management in the field of welding.
This fourth edition cancels and replaces the third edition (ISO 5817:2014), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— the document was editiorial updated,
— figures to imperfection no. 1.4, 1.11, 1.16, 1.19, 1.11 and 4.1 in Table 1 have been changed.
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 2021 – All rights reserved

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oSIST prEN ISO 5817:2021
ISO/DIS 5817:2021(E)

Introduction
This document should be used as a reference in the drafting of application codes and/or other application
standards. It contains a simplified selection of fusion weld imperfections based on the designations
given in ISO 6520-1.
Some of the imperfections described in ISO 6520-1 have been used directly and some have been grouped
together. The basic numerical referencing system from ISO 6520-1 has been used.
The purpose of This document is to define dimensions of typical imperfections which might be
expected in normal fabrication. It may be used within a quality system for the production of welded
joints. It provides three sets of dimensional values from which a selection can be made for a particular
application. The quality level necessary in each case should be defined by the application standard or
the responsible designer in conjunction with the manufacturer, user and/or other parties concerned.
The quality level shall be prescribed before the start of production, preferably at the enquiry or order
stage. For special purposes, additional details may be prescribed. If the welds will be subsequently
coated with a protective coating, lining or paint, the welds might require more thorough post weld
treatment or surface finishing to achieve the requirements in ISO 8501-3.
The quality levels given in this document provide basic reference data and are not specifically related
to any particular application. They refer to types of welded joint in fabrication and not to the complete
product or component itself. It is possible, therefore, that different quality levels are applied to
individual welded joints in the same product or component.
It would normally be expected that for a particular welded joint the dimensional limits for imperfections
could all be covered by specifying one quality level. In some cases, it may be necessary to specify
different quality levels for different imperfections in the same welded joint. The choice of quality
level for any application should take account of design considerations, subsequent processing (e.g.
surfacing), mode of stressing (e.g. static, dynamic), service conditions (e.g. temperature, environment)
and consequences of failure. Economic factors are also important and should include not only the cost
of welding but also of inspection, testing and repair.
Although this document includes types of imperfection relevant to the fusion welding processes listed
in Clause 1, only those which are applicable to the process and application in question need to be
considered.
Imperfections are quoted in terms of their actual dimensions, and their detection and evaluation
may require the use of one or more methods of non-destructive testing. The detection and sizing of
imperfections is dependent on the testing methods and the extent of testing specified in the application
standard or contract.
This document does not address the methods used for the detection of imperfections. However,
ISO 17635 contains a correlation between the quality level and acceptance level for different NDT
methods.
This document is directly applicable to visual testing of welds and does not include details of
recommended methods of detection or sizing by non-destructive means. It should be considered
that there are difficulties in using these limits to establish appropriate criteria applicable to non-
destructive testing methods such as ultrasonic testing (UT), radiographic testing (RT), eddy current
testing (ET), penetrant testing (PT), magnetic particle testing (MT) and may need to be supplemented
by requirements for inspection, examining and testing.
The values given for imperfections are for welds produced using normal welding practice. Requirements
for smaller (more stringent) values as stated in quality level B may include additional manufacturing
processes, e.g. grinding, TIG dressing.
Annex C gives additional guidance for welds subject to fatigue.
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oSIST prEN ISO 5817:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 5817:2021(E)
Welding — Fusion-welded joints in steel, nickel, titanium
and their alloys (beam welding excluded) — Quality levels
for imperfections
1 Scope
This document provides quality levels of imperfections in fusion-welded joints (except for beam
welding) in all types of steel, nickel, titanium and their alloys. It applies to material thickness ≥ 0,5 mm.
It covers fully penetrated butt welds and all fillet welds. Its principles can also be applied to partial-
penetration butt welds.
Quality levels for beam-welded joints in steel are presented in ISO 13919-1.
Three quality levels are given in order to permit application to a wide range of welded fabrication. They
are designated by symbols B, C and D. Quality level B corresponds to the highest requirement on the
finished weld.
Several types of loads are considered, e.g. static load, thermal load, corrosion load, pressure load.
Additional guidance on fatigue loads is given in Annex C.
The quality levels refer to production and good workmanship.
This document is applicable to
a) non-alloy and alloy steels,
b) nickel and nickel alloys,
c) titanium and titanium alloys,
d) manual, mechanized and automated welding,
e) all welding positions,
f) all types of welds, e.g. butt welds, fillet welds and branch connections
g) the following welding processes and their sub-processes, as defined in ISO 4063:
— 11 metal arc welding without gas protection;
— 12 submerged arc welding;
— 13 gas-shielded metal arc welding;
— 14 gas-shielded arc welding with non-consumable tungsten electrode;
— 15 plasma arc welding;
— 31 oxyfuel gas welding (for steel only).
Metallurgical aspects, e.g. grain size, hardness, are not covered by this document.
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 2021 – All rights reserved 1

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oSIST prEN ISO 5817:2021
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ISO 6520-1, Welding and allied processes — Classification of geometric imperfections in metallic
materials — Part 1: Fusion welding
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 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 https:// www .electropedia .org/
3.1
quality level
description of the quality of a weld on the basis of type, size and amount of selected imperfections
3.2
fitness for purpose
ability of a product, process or service to serve a defined purpose under specific conditions
3.3
short imperfections in welds 100 mm long or longer
imperfections whose total length is not greater than 25 mm in the 100 mm of the weld which contains
the greatest number of imperfections
3.4
short imperfections in welds less than 100 mm long
imperfections whose total length is not greater than 25 % of the length of the weld
3.5
systematic imperfections
imperfections that are repeatedly distributed in the weld over the weld length to be examined, the size
of a single imperfection being within the specified limits
3.6
projected area
area where imperfections distributed along the volume of the weld under consideration are imaged
two-dimensionally
Note 1 to entry: In contrast to the cross-sectional area, the occurrence of imperfections is dependent on the weld
thickness when exposed radiographically (see Figure 1).
3.7
cross-sectional area
area to be considered after fracture or sectioning
3.8
smooth weld transition
even surface with no irregularities or sharpness at the transition between the weld bead and the parent
material and/or the adjacent welding bead(s)
3.9
fatigue class
FATx
6
classification reference to S-N curve, in which x is the stress range in MPa at 2 · 10 cycles
Note 1 to entry: Fatigue properties are described by S-N-Curves (Stress-Number of cycle- curves).
Note 2 to entry: See Annex C.
2 © ISO 2021 – All rights reserved

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oSIST prEN ISO 5817:2021
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Key
1 direction of X-rays 3 6-fold thickness 5 2-fold thickness
2 4 pores per volume unit 4 3-fold thickness 6 1-fold thickness
Figure 1 — Radiographic films of specimens with identical occurrence of pores per volume unit
4 Symbols
The following symbols are used in Table 1 and Table C.1.
a nominal throat thickness of the fillet weld (see also ISO 2553)
a actual throat thickness (throat thickness of the finalized weld) (see ISO TR 25901-1)
A
A area surrounding the gas pores
b width of weld reinforcement
d diameter of gas pore
d diameter of area surrounding the gas pores
A
h height or width of imperfection
l length of imperfection in longitudinal direction of the weld
l length of projected or cross-sectional area
p
s nominal butt weld thickness
t wall or plate thickness (nominal size)
w width of the weld or width or height of the cross-sectional area
p
z leg length of a fillet weld (see also ISO 2553)
α angle of weld toe
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oSIST prEN ISO 5817:2021
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β angle of angular misalignment
i penetration in fillet welds
r radius of weld toe
5 Assessment of imperfections
Limits for imperfections are given in Table 1.
If, for the detection of imperfections, macro-examination is used, only those imperfections shall be
considered which can be detected with a maximum of tenfold magnification. Excluded from this are
micro lack of fusion (see Table 1, 1.5) and microcracks (see Table 1, 2.2).
Systematic imperfections are only permitted in quality level D, provided other requirements of Table 1
are fulfilled.
A welded joint should usually be assessed separately for each individual type of imperfection (see
Table 1, 1.1 to 3.2).
Different types of imperfection occurring at any cross-section of the joint need special consideration
(see multiple imperfections in Table 1, 4.1).
The limits for multiple imperfections (see Table 1) are only applicable for cases where the requirements
for a single imperfection are not exceeded.
Any two adjacent imperfections separated by a distance smaller than the major dimension of the
smaller imperfection shall be considered as a single imperfection.
4 © ISO 2021 – All rights reserved

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© ISO 2021 – All rights reserved 5
Table 1 — Limits for imperfections
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
1  Surface imperfections
1.1 100 Crack ≥ 0,5 Not permitted Not permitted Not permitted
1.2 104 Crater crack ≥ 0,5 Not permitted Not permitted Not permitted
1.3 2017 Surface pore On the weld face or the weld root 0,5 to 3 butt welds d ≤ 0,3 s Not permitted Not permitted
Maximum dimension of a single pore fillet welds d ≤ 0,3 a
A
> 3 butt welds d ≤ 0,3 s, but butt welds d ≤ 0,2 s, but Not permitted
max. 3 mm max. 2 mm
fillet welds d ≤ 0,3 a , fillet welds d ≤ 0,2 a , but
A A
but max. 3 mm max. 2 mm
1.4 2025 End crater —  butt welds 0,5 to 3 butt welds h ≤ 0,2 t Not permitted Not permitted
pipe
d ≤ 0,3 s
fillet welds h ≤ 0,2a ,
A
d ≤ 0,3 a
—  fillet welds > 3 butt welds h ≤ 0,2 t, but butt welds h ≤ 0,1 t, but Not permitted
max. 2 mm max. 1 mm
d ≤ 0,3 s, but max. 3 mm d ≤ 0,2 s, but max. 2 mm
fillet welds h ≤ 0,2 a , fillet welds h ≤ 0,1 a , but
A A
but max. 2 mm max. 1 mm
d ≤ 0,3 a , but max. d ≤ 0,2 a , but max. 2 mm
A A
3 mm
1.5 401 Lack of fusion — ≥ 0,5 Not permitted Not permitted Not permitted
(incomplete
fusion)
Micro lack of Only detectable by micro examination ≥ 0,5 Permitted Permitted Not permitted
fusion
1.6 4021 Incomplete Only for single side butt welds ≥ 0,5 Short imperfections: Not permitted Not permitted
root penetra- h ≤ 0,2 t but max. 2 mm
tion

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6 © ISO 2021 – All rights reserved
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
1.7 5011 Continuous Smooth transition is required. 0,5 to 3 Short imperfections: Short imperfections: Not permitted
undercut This is not regarded as a systematic imperfec- h ≤ 0,2 t h ≤ 0,1 t
tion.
5012 Intermittent > 3 h ≤ 0,2 t, but max. 1 mm h ≤ 0,1 t, but max. 0,5 mm h ≤ 0,05 t, but max.
undercut 0,5 mm
(short imper-
fection)
1.8 5013 Shrinkage Smooth transition is required. 0,5 to 3 Short imperfections: Short imperfections: Not permitted
grooves h ≤ 0,1 t + 0,2 mm h ≤ 0,1 t
  > 3 Short imperfections: Short imperfections: Short imperfections:
h ≤ 0,2 t, but max. 2 mm h ≤ 0,1 t, but max.1 mm h ≤ 0,05 t, but max.
0,5 mm
1.9 502 Excess weld Smooth transition is required between the cap ≥ 0,5 h ≤ 0,25 b + 1 mm, but h ≤ 0,15 b + 1 mm , but h ≤ 0,1 b + 1 mm ,but
metal (butt of the weld and the plate surface and/or the adja- max. 10 mm max. 7 mm max. 5 mm
weld) cent welding bead(s)

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© ISO 2021 – All rights reserved 7
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
1.10 503 Excessive con- Smooth transition is required between the cap ≥ 0,5 h ≤ 0,25 b + 1 mm, but h ≤ 0,15 b + 1 mm, but h ≤ 0,1 b + 1 mm, but
vexity (fillet of the weld and the plate surface and/or the adja- max. 5 mm max. 4 mm max. 3 mm
weld) cent welding bead(s)
1.11 504 Excessive 0,5 to 3 h ≤ 0,6 b + 1 mm h ≤ 0,3 b + 1 mm h ≤ 0,1 b + 1 mm
penetration
> 3 h ≤ 1,0 b + 1 mm, but h ≤ 0,45 b +1 mm,but max. h ≤ 0,2 b + 1 mm,but
max. 5 mm 4 mm max. 3 mm

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8 © ISO 2021 – All rights reserved
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
1.12 505 Incorrect weld —  butt welds ≥ 0,5 α ≥ 90° α ≥ 110° α ≥ 150°
toe

—  fillet welds ≥ 0,5 α ≥ 90° α ≥ 100° α ≥ 110°

α ≥ α and α ≥ α
1 2
1.13 506 Overlap ≥ 0,5 h ≤ 0,2 b Not permitted Not permitted
1.14 509 Sagging Smooth transition is required 0,5 to 3 Short imperfections: Short imperfections: Not permitted
h ≤ 0,25 t h ≤ 0,1 t
511 Incompletely > 3 Short imperfections: Short imperfections: Short imperfections:
filled groove h ≤ 0,25 t, but max. h ≤ 0,1 t, but max. 1 mm h ≤ 0,05 t, but max.
2 mm 0,5 mm
1.15 510 Burn through — ≥ 0,5 Not permitted Not permitted Not permitted

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© ISO 2021 – All rights reserved 9
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
1.16 512 Excessive In cases where an asymmetric fillet weld has not ≥ 0,5 h ≤ 0,2 a + 2 mm h ≤ 0,15 a + 2 mm h ≤ 0,15 a + 1,5 mm
A A A
asymmetry been prescribed.
of fillet weld
(excessive
unequal leg
length)
h= |Z - Z |
1 2
1.17 515 Root concavity Smooth transition is required. 0,5 to 3 h ≤ 0,1 t + 0,2 mm Short imperfections: Not permitted
h ≤ 0,1 t
  > 3 Short imperfections: Short imperfections: Short imperfections:
h ≤ 0,2 t, but max. 2 mm h ≤ 0,1 t, but max. 1 mm h ≤ 0,05 t, but max.
0,5 mm

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10 © ISO 2021 – All rights reserved
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
1.18 516 Root porosity Spongy formation at the root of a weld due to ≥ 0,5 Locally permitted Not permitted Not permitted
bubbling of the weld metal at the moment of
solidification (e. g. lack of gas backing)
1.19 517 Poor restart ≥ 0,5 Permitted Not permitted Not permitted
The limit depends on
the type of imperfec-
tion occurred due to
restart.
1.20 5213 Insufficient Not applicable to processes with proof of greater 0,5 to 3 Short imperfections: Short imperfections: Not permitted
throat thick- depth of penetration h ≤ 0,1 a + 0,2 mm h ≤ 0,2 mm
ness
  > 3 Short imperfections: Short imperfections: Not permitted
h ≤ 0,1 a + 0,3 mm, but h ≤ 0,1 a + 0,3 mm,but
max. 2 mm max. 1 mm
1.21 5214 Excessive The actual throat thickness of the fillet weld is ≥ 0,5 Permitted h ≤ 0,2 a + 1 mm, but max. h ≤ 0,15 a + 1 mm, but
throat thick- too large. 4 mm max. 3 mm
ness

1.22 601 Stray arc — ≥ 0,5 Permitted, if the prop- Not permitted Not permitted
erties of the parent
metal are not affected.

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© ISO 2021 – All rights reserved 11
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
1.23 602 Spatter — ≥ 0,5 Acceptance depends on Acceptance depends on Acceptance depends on
application, e.g. materi- application, e.g. material, application, e.g. material,
al, corrosion protection corrosion protection corrosion protection
1.24 610 Temper colour — ≥ 0,5 Acceptance depends on Acceptance depends on Acceptance depends on
(Discoloura- application, e.g. materi- application, e.g. material, application, e.g. material,
tion) al, corrosion protection corrosion protection corrosion protection
2  Internal imperfections
2.1 100 Cracks All types of crack except microcracks and crater ≥ 0,5 Not permitted Not permitted Not permitted
cracks
2.2 1001 Microcracks A crack usually only visible under the microscope ≥ 0,5 Permitted Acceptance depends on Acceptance depends on
(50 × ) type of parent metal with type of parent metal
particular reference to with particular refer-
crack sensitivity ence to crack sensitivity
2.3 2011 Gas pore The following conditions and limits for imper-
fections shall be fulfilled. See also Annex A for
2012 Uniformly
information.
distributed
a1)  Maximum dimension of the area of the ≥ 0,5 For single layer: ≤ 2,5 % For single layer: ≤ 1,5 % For single layer: ≤ 1 %
porosity
imperfections (inclusive of systematic imperfec-
For multi-layer: ≤ 5 % For multi-layer: ≤ 3 % For multi-layer: ≤ 2 %
tion) related to the projected area
NOTE  The porosity in the project area depends
on the numbers of layers (volume of the weld).
a2)  Maximum dimension of the cross-sectional ≥ 0,5 ≤ 2,5 % ≤ 1,5 % ≤ 1 %
area of the imperfections (inclusive of systematic
imperfection) related to the fracture area (only
applicable to test pieces: production test, welder
or procedure qualification tests)
b)  Maximum dimension for a single pore for ≥ 0,5
—  butt welds d ≤ 0,4 s, but max. 5 mm d ≤ 0,3 s, but max. 4 mm d ≤ 0,2 s, but max. 3 mm
—  fillet welds d ≤ 0,4 a, but max. 5 mm d ≤ 0,3 a, but max. 4 mm d ≤ 0,2 a, but max. 3 mm

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12 © ISO 2021 – All rights reserved
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
2.4 2013 Clustered ≥ 0,5 d ≤ 25 mm d ≤ 20 mm d ≤ 15 mm
A A A
(localized)
or or or
porosity
d ≤ w d ≤ w d ≤ w /2
A, max p A, max p A, max p
  Reference length for l is 100 mm.
p
The total gas pore area within the cluster is rep-
resented by a circle of diameter d surrounding
A
all the gas pores.
The requirement for a single gas pore shall be
met by all the gas pores within this circle.
A permitted porous area shall be local. The possi-
bility of the pore cluster masking other imperfec-
tions shall be taken into consideration.
If D is less than d or d , whichever is smaller,
A1 A2
then the total gas pore area is represented by a
circle of diameter d , where d = d + d + D.
AC AC A1 A2
Systematic cluster porosity is not permitted.
d corresponds to d , d or d , whichever is
A A1 A2 AC
applicable.

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© ISO 2021 – All rights reserved 13
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No. Remarks
ISO 6520-1 designation
D C B
mm
2.5 2014 Linear poros- —  butt welds ≥ 0,5 h ≤ 0,4 s, but max. 4 mm h ≤ 0,3 s, but max. 3 mm h ≤ 0,2 s, but max. 2 mm
ity
l ≤ s, but max. 75 mm l ≤ s, but max. 50 mm l ≤ s, but max. 25 mm
—  fillet welds ≥ 0,5 h ≤ 0,4 a, but max. 4 mm h ≤ 0,3 a, but max. 3 mm h ≤ 0,2 a, but max. 2 mm
l ≤ a, but max. 75 mm l ≤ a, but max. 50 mm l ≤ a, but max. 25 mm
  Case 1 (D > d )
2
Case 2 (D < d )
2
Reference length for l is 100 mm.
p
For case 1: d = h
1
For case 2: d + d + D = h
1 2

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oSIST prEN ISO 5817:2021
ISO/DIS 5817:2021(E)

14 © ISO 2021 – All rights reserved
Table 1 (continued)
t Limits for imperfections for quality levels
Reference to Imperfection
No.
...