ISO-8502-9-1998.pdf
STD-IS0 8502-9-ENGL 1998 I 4851903 0805821 194 W INTERNATIONAL STANDARD IS0 8502-9 First edition 1998-05-01 Corrected and reprinted 1999-1 2-1 5 Preparation of steel substrates before application of paints and related products - Tests for the assessment of surface cleanliness - Part 9: Field method for the conductometric determination of water-soluble salts Préparation des subjectiles dacier avant application de peintures et de produits assimilés - Essais pour apprécier la propreté dune surface - Partie 9: Méthode in situ pour la détermination des sels solubles dans leau par conductimétrie This material is reproduced from IS0 documents under International Organization for Standardization (ISO) Copyright License Number HIS/CC/I 996. Not for resale. No part oftliese IS0 documents may be reprodiiced in any form, electronic retrieval system or otherwise, except as allowed in the copyright law ofthe country of lise, or with the prior written consent of IS0 (Case poslale 56,121 I Geneva 20, Switzerland, Fax +41 22 734 10 79), IHS or the IS0 Licensors members. Reference number IS0 8502-9: 1998(E) STDOIS0 8502-9-ENGL 3998 4853903 0805822 020 IS0 8502-9: 1 998( E) 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. Intemational Standard IS0 8502-9 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. IS0 8502 consists of the following parts, under the general title Preparation o f steel substrates before application of paints and related products - Tests for the assessment of surface cleanliness: - Part I: Field test for soluble iron corrosion products Technical Report - Part 2: Laboratory determination of chloride on cleaned surfaces - Part 3: Assessment of dust on steel sugaces prepared for painting (pressure-sensitive tape method) - Part 4: Guidance on the estimation o f the probability of condensation prior to paint application Q IS01998 All rights reserved. UnleSS otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in wrifng from the publisher. Intemational Organization for Standardization Case postale 56 CH-121 1 Genève 20 Switzerland Intemet central 8 iso.ch X.400 c=ch; a3400net; p=iso; o=isocs; s=central Printed in Switzerland COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services o IS0 STD-IS0 8502-9-ENGL I998 H 4853903 0805823 Tb7 9 IS0 8502-9:1998(E) - Part 5: Measurement of chloride on steel sutj5aces prepared for painting - Ion detection tube method - Part 6: Extraction o f soluble contaminants for analysis - The Bresle method - Part 7: Field method for determination o f oil and grease - Part 8: Field method for refractometric determination o f moisture - Part 9: Field method for the conductometric determination of water-soluble salts - Part 10: Field method for the titrimetric determination of chloride . II1 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services - STD*ISO 8502-9-ENGL L998 H 4853903 0805824 9T3 H IS0 8502-9:1998(E) Q IS0 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 IS0 8501, IS0 8502 and IS0 8503 have been prepared 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 protective coating system to be applied to the steel surface. Neither do they contain recornendations 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 Intemational 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 o f sulface cleanliness; IS0 8503 Su flace roughness characteristics o f blast-cleaned steel substrates; IS0 8504 Surface preparation methods. Each of these International Standards is in turn divided into separate parts. iv COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services STD=ISO 4502-7-ENGL 1778 4853703 0805425 43T IS0 8502-9: 1998(E) This part of IS0 8502 describes a field method for the assessment of the total amount of water- soluble salts, the salts being regarded as forming one single contaminant. The more aggressive contaminants causing corrosion and blistering (the ionic species) can easily be dissolved off and determined rapidly by this method. Consequently, the less aggressive and not so easily dissolved minor part of contaminant will remain un-assessed. For additional information on the test method, its potential and its limitations, see BRESLE, Å., Conductometric determination of salts on steel surfaces, MP (Materials Perf¿mzance), June 1995, Vol. 34, No. 6, pp. 35-37, NACE International, Houston TX, USA. Rusty steel substrates, particularly those of rust grades C or D (see IS0 8501-i), even when blast-cleaned to preparation grade Sa3 (see ISO8501-1 and ISO8501-2), may still be contaminated by water-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 blister formation and accumulations of rust that destroy the adhesion between the substrate and the applied protective coating. V COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services STD.IS0 6502-9-ENCL 1998 4853903 080582b 776 W INTERNATIONAL STANDARD 0 IS0 IS0 8502-9:1998(E) Preparation of steel substrates before application of paints and related products - Tests for the assessment of surface cleanliness - Part 9: Field method for the conductometric determination of water-soluble salts 1 Scope This part of IS0 8502 describes a field method for the assessment of the total surface density of various water-soluble salts (mostly chlorides and sulfates) on steel surfaces before and/or after surface preparation. The individual surface densities of chlorides, sulfates, etc., cannot be determined by this method. This method assesses ionic contaminants only. These represent the greater part of the contamination. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of IS0 8502. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreement based on this part of IS0 8502 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 3696: 1987, Water for analytical laboratory use - Specification and test methods. IS0 8502-6: 1995, Preparation o f steel substrates before application o f paints and related products - Tests for the assessment of su$ace cleanliness - Part 6: Extraction o f soluble contaminants for analysis - The Bresle method. 3 Principle The salts on the given area of the steel surface are dissolved by the Bresle method (see IS0 8502-6), using water as solvent. The conductivity of the solution thus obtained is measured. Finally, the total surface density of the salts in this area is calculated by a simple but sufficiently accurate equation. 1 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services vSTD*ISO 8502-9-ENGL 1998 4851903 0805827 ho2 W IS0 8502-9: 1998( E) Q IS0 4 Solvent Water of at least grade 3 purity in accordance with IS0 3696. NOTE - Usually, distilled or de-ionized water of conductivity less than 0,5 mS/m (5 km) meets this requirement. 5 Apparatus and materials 5 . 1 Conductometer, with temperature compensation and sufficient range, e.g. from O mS/m (O pS/cm) to 200 mS/m (2000 pS/cm). 5 . 2 Glass beaker, of convenient size and shape for housing the electrode end of the conductometer (5.1) during measurement. 5 . 3 Standard adhesive patch, as specified in 4.1 of IS0 8502-6: 1995, e.g. of size A-1250. NOTE- The patch should not cause any noticable contamination of the extraction liquid. Certain patches are available today which are guaranteed to cause an ionic contamination of less than 7 mg/m2, which is generally satisfactory. If there is no guarantee or if improved accuracy is required, then a blank test is recommended. 5.4 Syringe, as specified in 4.2 of IS0 8502-61995. 6 Procedure 6 . 1 Preparation of water and blank test 6 . 1 . 1 Pour into the beaker (5.2) an amount of water (clause 4) that is just large enough for the operation of the conductometer (5.1). Usually a volume between 10 ml and 20 ml is needed. To prevent foreign matter inside the beaker and syringe, and on the conductometer probe, from influencing the result, carry out the following blank test. 6 . 1 . 2 Completely fill the syringe (5.4) with water from the beaker. Then empty the syringe back into the beaker. 6 . 1 . 3 Immerse the electrodes of the conductometer fully in the water in the beaker and agitate gently. Record the conductivity (yi) and the units in which it is expressed, for example pS/cm. 6 . 2 Removal of salts from the steel surface 6 . 2 . 1 Follow the procedure specified in clause 5 of IS0 8502-6: 1995, subject to the following specific requirements. 63.2 Fill the syringe with about one-quarter of the water contained in the beaker. 6 . 2 . 3 After 1 min, suck the water back into the syringe cylinder (see 5.6 of IS0 8502-6: 1995). 2 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services STD-IS0 8502-9-ENGL 1998 4853903 0805828 549 IS0 8502-9:1998(E) 6.2.4 Without removing the syringe needle from the patch, re-inject the water into the patch compartment and then suck the water back into the syringe cylinder. Repeat until 10 cycles of injection and sucking have been completed (see 5.7 of IS0 8502-6: 1995). 6.2.5 At the end of the 10th cycle, retrieve as much as possible of the water from the patch compartment and transfer to the beaker (5.2), thus restoring its content to nearly the original volume in 6.1.1 (see 5.8 of 8502-6: 1995). 6.3 Conductometric measurement Immerse the electrodes of the conductometer fully in the now contaminated water in the beaker, and record the conductivity (y2) expressed in the same units as in 6.1.3. 7 Expression of results The total surface density pA of the salts is given by the equation m P A = 2 .( 1) where rn is the mass of salts dissolved from that part of the surface which is covered by the patch compartment; A is the area of that part of the surface. In this case, rn is given by m = c . V . Ay .( 2) where -2 -1 c is an empirical constant approximately equal to 5 kg.m .S (see also clause 8); V is the original volume of water in the beaker (see 6.1. i); Ay is the change in conductivity, i.e. the difference between the conductivity measured in 6.3 ( y2) and the conductivity measured in 6.1.3 (y,). From (i) and (2), it follows that P A Since c = that P A - c . V . Ay - A 2 -1 5 kg.m- .S , and if for example V = 10 ml (6.1.1) andA = 1250 mm2 (5.3), it follows = Ay.40. kg.m-'.S-' .( 4) 3 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services Equation (4) gives pA expressed in the SI unit kg/m2. Multiplying the numerical value obtained from equation (4) by lo6 gives pA in mg/m2. Multiplying the numerical value obtained from equation (4) by lo5 gives pA in pg/cm2. Inserting different values of V in equation (3) for other volumes of water gives equations similar to equation (4). Three straight lines corresponding to three different equations are plotted in figure 1. f m In u- O ) . . . c Y , U L 1 O00 L = In d m 4 - O t 500 O 50 100 150 200 Change in conductivity, A a lpS/crn) NOTE- Each straight line corresponds to a different volume of water in the beaker. In each case, the patch size is A-1250, in accordance with IS0 8502-6. Figure 1 - The total surface density pA of the salts as a function of the change in conductivity A y 4 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information H
