ISO 8502-2:2017 塗料および関連製品を塗布する前の鋼基板の準備—表面の清浄度を評価するためのテスト—パート2：洗浄された表面の塩化物の実験室での測定 | ページ 2

Foreword

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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.

This third edition cancels and replaces the second edition (ISO 8502-2:2005), which has been technically revised with the following changes:

• a) the analysis method has been deleted;
• b) a selection of analysis methods from other standards have been added;
• c) the coulometric method has been added and briefly described in an informative annex;
• d) the formula in Clause 7 has been replaced by Formula (1) transforming chloride concentration in a solution to amount of chloride on the surface;
• e) the document has been editorially revised.

ISO 8502 consists of the following parts, under the general title Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness:

• Part 2: Laboratory determination of chloride on cleaned surfaces
• Part 3: Assessment of dust on steel surfaces prepared for painting (pressure-sensitive tape method)
• Part 4: Guidance on the estimation of the probability of condensation prior to paint application
• Part 5: Measurement of chloride on steel surfaces prepared for painting (ion detection tube method)
• Part 6: Extraction of soluble contaminants for analysis — The Bresle method
• Part 9: Field method for the conductometric determination of water-soluble salts
• Part 11: Field method for the turbidimetric determination of water-soluble sulfate
• Part 12: Field method for the titrimetric determination of water-soluble ferrous ions

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 as follows:

• a) presence of rust and mill scale;
• b) presence of surface contaminants, including salts, dust, oils and greases;
• c) surface profile.

The ISO 8501, ISO 8502 and ISO 8503 series of International Standards have been prepared to provide methods of assessing these factors, while the ISO 8504 series 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 series of 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, and
• within the capability of the cleaning procedure specified.

The four series of International Standards referred to above deal with the following aspects of preparation of steel substrates before application of paints and related products:

• ISO 8501 on visual assessment of surface cleanliness;
• ISO 8502 on tests for the assessment of surface cleanliness;
• ISO 8503 on surface roughness characteristics of blast-cleaned steel substrates;
• ISO 8504 on surface preparation methods.

Each of these International Standards is in turn divided into separate parts. This part of ISO 8502 describes a method for the assessment of chloride-containing salts that are readily soluble in water and are present on a steel surface. Rusted steel substrates, particularly of rust grades C or D (see ISO 8501-1), even when blast cleaned to preparation grade Sa 3 (see ISO 8501-1) can still be contaminated by soluble salts and corrosion products. These compounds are almost colourless and are localized at the lowest point of the rust pits. If they are not removed prior to painting, chemical reactions can result in large accumulations of rust that destroy the adhesion between the substrate and the applied protective coating. Even if the salt is readily soluble in water, it is often impossible to remove it completely from the surface by a simple washing such as that described in this procedure. The method does not therefore determine the total amount of chloride on the surface but gives an indication of the cleanliness level of the surface. Prolonging the washing time should remove a larger proportion of the salt.

1 Scope

This part of ISO 8502 describes a method for the determination of chloride-containing salts that are readily soluble in water and are present on a steel surface. The method is also applicable to previously coated surfaces. This part of ISO 8502 includes a method, applicable in the field or in the laboratory, for washing off the surface while several methods are referred to for chloride analyses.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

Bibliography