ISO 8501-2:1994 塗料および関連製品を塗布する前の鋼基板の準備—表面の清浄度の視覚的評価—パート2：以前のコーティングを局所的に除去した後の以前にコーティングされた鋼基板の準備グレード | ページ 2

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 nongovernmental, 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.

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 ISO 8501-2 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.

ISO 8501 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 1: 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 blastcleaned with different abrasives.
• Part 2: Preparation grades of previously coated steel substrates after localized removal of previous coatings.
• Part 3: Preparation grades of welds, cut edges and surface imperfections.

Annexes A to J form an integral part of this part of ISO 8501.

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.

International Standards ISO 8501, ISO 8502 and ISO 8503 have been prepared to provide methods of assessing these factors, while ISO 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 protective 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 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:

Each of these International Standards is in turn divided into separate parts.

This part of ISO 8501 supplements ISO 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 2½ and P Ma have been taken from DIN 55 928, Part 4, Supplement 1 (August 1978) and Supplement 2 (January 1986), respectively.

The basis of this part of ISO 8501 is the experience that complete removal of 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 contribution 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 significantly damaged;
• real savings in costs for the maintenance work should be made possible.

1 Scope

This part of ISO 8501 specifies a series of preparation grades for steel surfaces after localized removal of previous paint coatings The various preparation grades are defined by written descriptions (see clause 4) together with the representative photographic examples given in ISO 8501-1. In addition, photographs showing examples of preparation grades P Sa 2½ and P Ma are given.

This part of ISO 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 ISO 8501 relates the cleanliness of a surface to its visual appearance. 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 ISO 8502. The roughness characteristics of the surface should also be considered by reference to ISO 8503.

2 Normative references

The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 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 ISO 8501 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.