SIST EN ISO 8501-3:2025
(Main)Preparation of steel substrates before application of paints and related products - Visual assessment of surface cleanliness - Part 3: Preparation grades of welds, edges and other areas with surface imperfections (ISO 8501-3:2025)
Preparation of steel substrates before application of paints and related products - Visual assessment of surface cleanliness - Part 3: Preparation grades of welds, edges and other areas with surface imperfections (ISO 8501-3:2025)
This document provides requirements to identify visible imperfections and defines three preparation grades for welds, edges and surfaces of steel to assist in achieving efficient corrosion protection. Such imperfections can be visible before or can become visible after an abrasive blast cleaning process.
NOTE Although this document has been developed specifically for preparation of steel, the defined preparation grades will generally be appropriate for use when preparing other metal surfaces e.g. aluminium, castings, if agreed.
Vorbereitung von Stahloberflächen vor dem Auftragen von Beschichtungsstoffen - Visuelle Beurteilung der Oberflächenreinheit - Teil 3: Vorbereitungsgrade von Schweißnähten, Kanten und anderen Flächen mit Oberflächenunregelmäßigkeiten (ISO 8501-3:2025)
In diesem Dokument werden die Anforderungen an die Bestimmung sichtbarer Unregelmäßigkeiten beschrieben und drei Vorbereitungsgrade für Schweißnähte, Kanten und Oberflächen bei Stahl definiert, um zum Erreichen eines wirksamen Korrosionsschutzes beizutragen. Solche Unregelmäßigkeiten können entweder vor dem Strahlen sichtbar sein oder nach dem Strahlen sichtbar werden.
ANMERKUNG Obwohl dieses Dokument insbesondere für die Vorbereitung von Stahl ausgearbeitet wurde, gelten die definierten Vorbereitungsgrade allgemein auch für die Vorbereitung anderer Metalloberflächen, z. B. von Aluminium oder Gussstücken, sofern dies vereinbart wurde.
Préparation des subjectiles d'acier avant application de peintures et de produits assimilés - Évaluation visuelle de la propreté de surface - Partie 3: Degrés de préparation des soudures, arêtes et autres zones représentant des imperfections du subjectile (ISO 8501-3:2025)
Le présent document fournit des exigences permettant d’identifier les imperfections visibles et définit trois degrés de préparation pour les soudures, les arêtes et la surface de l’acier afin d'aider à l’obtention d'une protection efficace contre la corrosion. Ces imperfections peuvent devenir visibles avant ou après une opération de décapage par projection d'abrasif.
NOTE Bien que le présent document ait été élaboré spécialement pour la préparation de l’acier, l’utilisation des degrés de préparation définis convient généralement, sous réserve d’accord, lors de la préparation de la surface d’autres métaux, par exemple, l’aluminium ou des produits moulés.
Priprava jeklenih podlag pred nanašanjem barv in sorodnih premazov - Vizualno ocenjevanje čistosti površine - 3. del: Stopnje priprave zvarov, robov in ostalih površin s površinskimi nepravilnostmi (ISO 8501-3:2025)
Ta dokument določa zahteve za prepoznavanje vidnih nepravilnosti ter opredeljuje tri stopnje priprave zvarov, robov in površin jekla kot pomoč pri učinkoviti zaščiti pred korozijo. Takšne nepravilnosti so lahko vidne pred postopkom peskanja z abrazivom oziroma se lahko pojavijo po njem. OPOMBA: Čeprav je bil ta dokument pripravljen posebej za pripravo jekla, so opredeljene stopnje priprave na splošno ustrezne tudi za pripravo drugih kovinskih površin, npr. aluminija, ulitkov (če je tako dogovorjeno).
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2025
Nadomešča:
SIST EN ISO 8501-3:2007
Priprava jeklenih podlag pred nanašanjem barv in sorodnih premazov - Vizualno
ocenjevanje čistosti površine - 3. del: Stopnje priprave zvarov, robov in ostalih
površin s površinskimi nepravilnostmi (ISO 8501-3:2025)
Preparation of steel substrates before application of paints and related products - Visual
assessment of surface cleanliness - Part 3: Preparation grades of welds, edges and
other areas with surface imperfections (ISO 8501-3:2025)
Vorbereitung von Stahloberflächen vor dem Auftragen von Beschichtungsstoffen -
Visuelle Beurteilung der Oberflächenreinheit - Teil 3: Vorbereitungsgrade von
Schweißnähten, Kanten und anderen Flächen mit Oberflächenunregelmäßigkeiten (ISO
8501-3:2025)
Préparation des subjectiles d'acier avant application de peintures et de produits
assimilés - Évaluation visuelle de la propreté de surface - Partie 3: Degrés de
préparation des soudures, arêtes et autres zones représentant des imperfections du
subjectile (ISO 8501-3:2025)
Ta slovenski standard je istoveten z: EN ISO 8501-3:2025
ICS:
25.220.10 Priprava površine Surface preparation
87.020 Postopki za nanašanje Paint coating processes
barvnih premazov
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 8501-3
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2025
EUROPÄISCHE NORM
ICS 25.220.10 Supersedes EN ISO 8501-3:2007
English Version
Preparation of steel substrates before application of paints
and related products - Visual assessment of surface
cleanliness - Part 3: Preparation grades of welds, edges
and other areas with surface imperfections (ISO 8501-
3:2025)
Préparation des subjectiles d'acier avant application de Vorbereitung von Stahloberflächen vor dem Auftragen
peintures et de produits assimilés - Évaluation visuelle von Beschichtungsstoffen - Visuelle Beurteilung der
de la propreté de surface - Partie 3: Degrés de Oberflächenreinheit - Teil 3: Vorbereitungsgrade von
préparation des soudures, arêtes et autres zones Schweißnähten, Kanten und anderen Flächen mit
représentant des imperfections du subjectile (ISO Oberflächenunregelmäßigkeiten (ISO 8501-3:2025)
8501-3:2025)
This European Standard was approved by CEN on 15 August 2025.
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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8501-3:2025 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 8501-3:2025) has been prepared by Technical Committee ISO/TC 35 "Paints
and varnishes" in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” 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 February 2026, and conflicting national standards
shall be withdrawn at the latest by February 2026.
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 8501-3:2007.
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 8501-3:2025 has been approved by CEN as EN ISO 8501-3:2025 without any
modification.
International
Standard
ISO 8501-3
Third edition
Preparation of steel substrates
2025-08
before application of paints
and related products — Visual
assessment of surface cleanliness —
Part 3:
Preparation grades of welds,
edges and other areas with surface
imperfections
Préparation des subjectiles d'acier avant application de peintures
et de produits assimilés — Évaluation visuelle de la propreté de
surface —
Partie 3: Degrés de préparation des soudures, arêtes et autres
zones représentant des imperfections du subjectile
Reference number
ISO 8501-3:2025(en) © ISO 2025
ISO 8501-3:2025(en)
© ISO 2025
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 8501-3:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General considerations . 2
4.1 General .2
4.2 Recommended workflow .2
5 Types of imperfections . 2
6 Preparation grades . 2
Annex A (informative) Preparation grade converted into weld quality levels based on ISO
5817:2023 . 10
Bibliography .13
iii
ISO 8501-3:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 35, Paints and varnishes, Subcommittee SC
12, Preparation of steel substrates before application of paints and related products, in collaboration with the
European Committee for Standardization (CEN) Technical Committee CEN/TC 139, Paints and varnishes, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 8501-3:2006), which has been technically
revised. The main changes compared to the previous edition are as follows:
— the illustrations of types of imperfections in Table 1 have been revised;
— Clause 2 and the Bibliography have been updated.;
— the introduction has been expanded.
A list of all parts in the ISO 8501 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO 8501-3:2025(en)
Introduction
The performance of protective coatings of paint and related products applied to steel is significantly affected
by the state of the steel surface immediately prior to painting. This document provides requirements for
steel building organizations to avoid unnecessary production costs for steel structures that will be painted.
The principal factors that are known to influence the performance of protective coatings of paints and
related products applied to steel are:
a) the presence of rust and mill scale
b) the presence of surface contaminants, including salts, dust, oils and greases
c) the surface profile.
ISO 8501, ISO 8502 and ISO 8503 series have been prepared to provide methods of assessing these factors,
while ISO 8504 series provide methods that are available for cleaning steel substrates, indicating the
capabilities of each in attaining specified levels of cleanliness.
The ISO 8501, ISO 8502, ISO 8503, and ISO 8504 series do not cover the protective coating system to be
applied to the steel surface. Nor do they cover the surface quality requirements for specific situations, even
though surface quality can have a direct influence on the choice of protective coating to be applied and its
performance. This subject matter is covered in other documents such as national standards and codes of
practice.
Imperfections at welds, edges and other areas of steel substrates are generally starting points for corrosion.
Such areas are also difficult to protect by application of paints and related products. To assist in achieving
efficient corrosion protection, this document describes certain imperfections and defines preparation
grades for such areas.
Steel imperfections can be generated in the manufacturing process or during handling, shipping, building
and erection of a steel structure and can affect the durability of a protective coating system if they are not
remedied.
The required preparation grade (P1 to P3) for a specific steel structure should be based on the required
longevity of the coating system and the corrosivity of the environment that the coated steel structure will
be exposed to.
The specified surface preparation grade should be compatible with other steel structures requirements, e.g.
those specified in the ISO 8501 series, ISO 5817, the EN 10025 series and the EN 10163 series.
v
International Standard ISO 8501-3:2025(en)
Preparation of steel substrates before application of paints
and related products — Visual assessment of surface
cleanliness —
Part 3:
Preparation grades of welds, edges and other areas with
surface imperfections
1 Scope
This document provides requirements to identify visible imperfections and defines three preparation grades
for welds, edges and surfaces of steel to assist in achieving efficient corrosion protection. Such imperfections
can be visible before or can become visible after an abrasive blast cleaning process.
NOTE Although this document has been developed specifically for preparation of steel, the defined preparation
grades will generally be appropriate for use when preparing other metal surfaces e.g. aluminium, castings, if agreed.
2 Normative references
The following documents are referred to in the text in such a way that some or all 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 8501-1, Preparation of steel substrates before application of paints and related products — Visual
assessment of surface cleanliness — Part 1: Rust grades and preparation grades of uncoated steel substrates and
of steel substrates after overall removal of previous coatings
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
as welded
condition of a weld, with or without imperfections, without any dressing (3.2)
3.2
dressing
grinding the surface of a weld to remove either visible (3.3) pores, lumps, welding spatter, excess metal and
sharp edges, or correcting undercut or weld toe imperfections
3.3
visible
capable of being seen without tools in normal environmental conditions
ISO 8501-3:2025(en)
4 General consideration
...
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