ISO 8501-2:1994

INTERNATIONAL IS0
STANDARD 8501 -2
First edition
NORME
Première edition
ilepsoe mnati~e
I NTERNATI O NALE
1994-12-15
M EXAYHAPOIH bl l?
CTAHAAPT
Preparation of steel substrates before application of paints
and related products -Visual assessment of surface
cleanliness -
Part 2:
Preparation grades of previously coated steel substrates after
localized removal of previous coatings
Préparation des subjectiles d'acier avant application de
- Évaluation visuelle de la
peintures et de produits assimilés
-
propreté d'un subjectile
Partie 2:
Degrés de préparation des subjectiles d'acier précédemment
revêtus après décapage localisé des couches
Reference number
Numero de référence
HOMep CCblilKM
IS0 8501-2:1994(E/F/R)
CD IS0 1994
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International Organization for Standardization
Case postale 56 CH-I211 Genève 20 Switzerland
Printed in Sweden/lmprimé en Suède. E Wezata 1995

IS0 8501 -2:1994( E/F/R)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0 collaborates
closely with the International Electrotechnical Commission (IEC) on all
matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting a
vote.
International Standard IS0 8501-2 was prepared by Technical Committee
ISOPC 35, Paints and varnishes, Subcommittee SC 12, Preparation of steel
substrates before application of paints and related products.
IS0@501 consists at present of the following parts, under the general title
Preparation of steel substrates before application of paints and related
products - Visual assessment of surface cleanliness :
- Part I: Rust grades and preparation grades of uncoated steel
substrates and of steel substrates after overall removal of previous
coatings.
- Informative Supplement to part 1: Representative photographic
examples of the change of appearance imparted to steel when blast-
cleaned with different abrasives.
- Part 2: Preparation grades of previously coated steel substrates after
localized removal of previous coatings.
- Part3: Preparation grades of welds, cut edges and surface
imperfections.
Annexes A to J form an integral part of this part of IS0 8501.
ii
-
IS0 8501-2:1994(E/F/R)
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération
mondiale d'organismes nationaux de normalisation (comités membres de
I'ISO). L'élaboration des Normes internationales est en général confiée aux
comités techniques de I'ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les
organisations internationales, gouvernementales et non gouvernementales,
en liaison avec I'ISO participent également aux travaux. L'ISO collabore
étroitement avec la Commission électrotechnique internationale (CEI) en ce
qui concerne la normalisation électrotechnique.
Les projets de Normes internationales adoptés par les comités techniques
sont soumis aux comités membres pour vote. Leur publication comme
Normes internationales requiert l'approbation de 75 % au moins des comités
membres votants.
IS0 8501-2 a été élaborée par le comité technique
La Norme internationale
lSO/TC 35, Peintures et vernis, sous-comité SC 12, Préparation de subjectiles
d'acier avant application de peintures et de produits assimilés.
L'ISO 8501 comprend les parties suivantes, présentées sous le titre général
Préparation des subjectiles d'acier avant application de peintures et de
produits assimilés - Évaluation visuelle de la propreté d'un subjectile :
- Partie I: Degrés de rouille et degrés de préparation des subjectiles
d'acier non recouverts et des subjectiles d'acier aprh décapage sur
toute la surface des revêtements précédents.
- Supplément informatifà la partie 1: Exemples de clichés représentatifs
du changement d'aspect communiqué B l'acier décapé avec des
abrasifs différents.
- Partie 2: Degrés de préparation des subjectiles d'acier précédemment
revêtus après décapage localisé des couchas.
- Partie3: Degrés de préparation des soudures, arêtes de coupe et
imperfections de surface.
Les annexes A à J font partie intégrante de la présente partie de I'ISO 8501.
iii
IS0 8501 -2: 1994( E/F/R)
iv
INTERNATIONAL STANDARD IS0 8501-2:1994(E)
Preparation of steel substrates before application of paints
and related products - Visual assessment of surface
cleanliness -
Part 2:
Preparation grades of previously coated steel substrates after
localized removal of previous coatings
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. The principal factors that are known to influence this
performance 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.
IS0 8501, IS0 8502 and IS0 8503 have been prepared
International Standards
to provide methods of assessing these factors, while IS0 8504 provides
guidance on the preparation methods that are available for cleaning steel
substrates, indicating the capabilities of each in attaining specified levels of
cleanliness.
These International Standards do not contain recommendations for the pro-
tective coating systems to be applied to the steel surface. Neither do they
contain recommendations for 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 on its performance. Such
recommendations are found in other documents such as national standards
IS0 8501 -2:1994( E)
and codes of practice. It will be necessary for the users of these International
Standards to ensure that the qualities specified are
- compatible and appropriate both for the environmental conditions to
which the steel will be exposed and for the protective coating system to be
used;
- within the capability of the cleaning procedure specified.
The four International Standards referred to above deal with the following
aspects of preparation of steel substrates:
IS0 8501 - Visual assessment of surface cleanliness;
IS0 8502 - Tests for the assessment of surface cleanliness;
IS0 8503 - Surface roughness characteristics of blast-cleaned steel sub-
strates;
IS0 8504 - Surface preparation methods.
Each of these International Standards is in turn divided into separate parts.
This part of IS0 8501 supplements IS0 8501-1. It identifies certain degrees of
visual cleanliness (designated as "preparation grades") following surface
preparation of steel surfaces after localized removal of previous paint
coatings. These levels of visual cleanliness are related to the common
methods of surface cleaning that are used prior to painting.
The photographic examples for preparation grades P Sa 2% and P Ma have
been taken from DIN 55 928, Part 4, Supplement 1 (August 1978) and
Supplement 2 (January 19861, respectively.
of this part of IS0 8501 is the experience that complete removal of
The basis
all previous paint coatings is not always necessary. This is especially true
where maintenance work is carried out at regular intervals. For localized
removal to be preferred, the following conditions should be fulfilled:
- the remaining intact coating should make a useful and durable contri-
bution to the new corrosion protection system and be compatible with it;
- during cleaning of locally corroded areas down to the substrate, the
coatings on the surrounding areas should not be irreparably or signifi-
cantly damaged;
IS0 8501-2:1994(E)
- real savings in costs for the maintenance work should be made
possible.
NOTE 1 This part of IS0 8501 contains the text in the three official languages of ISO,
namely English, French and Russian. It also contains the following annexes giving the
equivalent text in other languages, published under the responsibility of the respective
body indicated:
Annex A: Swedish (SIS)
Annex B: German (DIN)
Annex C: Dutch ("I)
Annex D: Italian (UNI)
Annex E: Spanish (AENOR)
Annex F: Portuguese (IPQ)
Annex G: Arabic (SASO)
Annex H: Japanese (JISC)
Annex J: Chinese (CSBTS)
IS0 8501-2:1994(E)
1 Scope
This part of IS0 8501 specifies a series of preparation grades for steel sur-
faces after localized removal of previous paint coatings The various prep-
aration grades are defined by written descriptions (see clause 4) together
with the representative photographic examples given in IS0 8501-1. In ad-
dition, photographs showing examples of preparation grades P Sa 2% and
P Ma are given.
This part of IS0 8501 is applicable to surfaces prepared for painting by
methods such as blast-cleaning, hand- and power-tool cleaning, and machine
abrading.
This part of IS0 8501 relates the cleanliness of a surface to its visual ap-
pearance. In many instances this is sufficient, but for coatings likely to be
exposed to severe environments, such as water immersion and continuous
condensation conditions, consideration should be given to testing for soluble
salts and other invisible contaminants on the visually clean surface by the
physical and chemical methods which form the subjects of the various parts
of IS0 8502. The roughness characteristics of the surface should also be
considered by reference to IS0 8503.
2 Normative references
The following standards contain provisions which, through reference in this
text, constitute provisions of this part of IS0 8501. At the time of publication,
the editions indicated were valid. All standards are subject to revision, and
parties to agreements based on this part of IS08501 are encouraged to
investigate the possibility of applying the most recent editions of the
standards indicated below. Members of IEC and IS0 maintain registers of
currently valid International Standards.
IS0 2409:1992, Paints and varnishes - Cross-cut test.
IS0 4624:1978, Paints and varnishes - Pull-off test for adhesion.
IS0 4627:1981, Paints and varnishes - Evaluation of the compatibility of a
product with a surface to be painted - Methods of test.
IS0 4628-1:1982, Paints and varnishes - Evaluation of degradation of paint
coatings - Designation of intensity, quantity and size of common types of
defect - Part 1: General principles and rating schemes.
IS0 8501-2:1994(E)
IS0 4628-2:1982, Paints and varnishes - Evaluation of degradation of paint
coatings - Designation of intensity, quantity and size of common types of
defect - Part 2: Designation of degree of blistering.
IS0 4628-3:1982, Paints and varnishes - Evaluation of degradation of paint
coatings - Designation of intensity, quantity and size of common types of
defect - Part 3: Designation of degree of rusting.
IS0 4628-4: 1982, Paints and varnishes - Evaluation of degradation of paint
coatings - Designation of intensity, quantity and size of common types of
defect - Part 4: Designation of degree of cracking.
IS0 4628-5:1982, Paints and varnishes - Evaluation of degradation of paint
coatings - Designation of intensity, quantity and size of common types of
defect - Part 5: Designation of degree of flaking.
IS0 4628-6:1990, Paints and varnishes - Evaluation of degradation of paint
coatings - Designation of intensity, quantity and size of common types of
defect - Part 6: Rating of degree of chalking by tape method.
IS0 8501-1:1988, 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 steel
substrates after overall removal of previous coatings.
3 Condition of the painted surface to be cleaned
The degrees of degradation which may be found on previously coated sur-
faces shall be assessed in accordance with IS0 4628, parts 1 to 6.
If possible, supplementary information about the previous coating, concern-
ing the generic type, number of coats applied, manufacturer's name, cor-
rosive contaminants, adhesion and film thickness, shall be given.
4 Preparation grades
4.1 General
A number of preparation grades, indicating the method of surface prep-
aration and the degree of clearling, are specified. The preparation grades are
defined (see 4.2, 4.3 and 4.4) by written descriptions of the surface appear-
ance after the cleaning operation.
IS0 8501-2:1994(E)
Each preparation grade is designated by the appropriate letters "Sa", "St" or
"Ma" to indicate the type of cleaning method used. The letter P before Sa,
St or Ma indicates only localized removal of previous paint coatings. The
number following, if any, indicates the degree of cleaning from mill scale,
rust and previous coatings.
It should be realized that the various methods of cleaning do not give com-
parable results. The degree of cleaning shall be compatible with the generic
type of coating system to be used for recoating.
Reference is made in 4.2 and 4.3 to the photographs in IS0 8501-1 which are
representative photographic examples of preparation grades.
NOTES
2 The term "foreign matter" used in 4.2, 4.3 and 4.4 includes water-soluble salts and
residues
...