INTERNATIONAL Iso STANDARD 8504-1 First edition 1992-12-01 Preparation of steel substrates before application of paints and related products — Surface preparation methods — Part 1: General principles Préparation des subjectiles d'acier avant application de peintures et de produits assimilés — Méthodes de préparation des subjectiles — Partie 1: Principes généraux Reference number (SO 8504-11992)ISO 8504-1:1992(E) Foreword ISO (the International Organization for Standardization) is 8 worldwide federation of national standards bodies (ISO member bodies). The work Of preparing Intemational Standards is normally carried out through ISO technical committees. Each member body interested in @ 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 Intemational 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 ISO 8504-1 was prepared by Technical Committee ISO/TC 36, Paints and varnishes, Sub-Committee SC 12, Preparation of steal substrates before application of paints and related products. 1SO 8504 consists of the following parts, under the general title Prepara- tion of steel substrates before application of paints and related products — Surface preparation methods: — Part 1: General principles — Part 2: Abrasive blast-cleaning — Part 3: Hand- and power-tool cleaning Further parts are planned. © 150 1992 [Al rights reserved. No part of this publication may be reproduced or utilized in any form oF by eny meens, electron or mechanical, Including photocopying and microti, without por mission In wring from the publisher Intemational Organization for Standardization. Case Postale 65 * CH-1211 Geneve 20 « Switzerland Printed in SwitrerlandIntroduction ‘The performance of protective coatings of paint and related products ap- plied to steel is significantly affected by the state of the steel surface im- mediately prior to painting. The principal factors that are known to influence this performance are ) the presence of rust and mill scale; b) the presence of surface contaminants, including salts, dust, oils and greases; ©) 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 avelable for cleaning stee! 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 fn 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: ISO 8501 — Visual assessment of surface cleanliness, |SO 8502 — Tests for the assessment of surface cleanliness; |SO 8503 — Surface roughness characteristics of blast-cleaned steel substrates; |SO 8504 — Surface preparation methods. Each of these International Standards is in turn divided into separate parts. The primary objective of surface preparation is to ensure the removal of deleterious matter and to obtain a surface that permits satisfactory ad-1SO 8504-1:1992(E) hesion of the priming paint to the steel. It should also assist in reducing the amounts of contaminants that initiate corrosion. This part of ISO 8504 describes the general principles for the selection of surface preparation methods. It should be read in conjunction with ISO 8504-2 and subsequent parts of ISO 8504 that describe particular surface preparation methods. It is stressed that there is a very wide variation in the condition of steel surfaces requiring cleaning prior to painting. This particularly applies to maintenance of an already coated structure. The age of the structure and its location, the quality of the previous surface, the performance of the existing coating system and the extent of breakdown, the type and inten- sity of previous and future corrosion environments, and the intended new coating system all infiuence the amount of treatment required.INTERNATIONAL STANDARD ISO 8504-1:1992(E) Preparation of steel substrates before application of paints and related products — Surface preparation methods — Part 1: General principles 1 Scope This part of ISO 8504 describes the general principles, for the selection of methods for the preparation of steel surfaces before coating with paints and related products. It also contains information on features that must be taken into account before certain surface preparation methods and preparation grades are selected and specified 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 8504. 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 8504 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. ISO 4628-2:1982, Paints and vamishes — Evaluation of degradation of paint coatings — Designation of in- tensity, quantity and size of common types of defect — Part 2: Designation of degree of blistering. 1SO 4628-3:1982, Paints and vamishes — Evaluation of degradation of paint coatings — Designation of in- tensity, quantity and size of common types of defect — Part 3: Designation of degree of rusting. 1) To be published. ISO 4628-4:1982, Paints and varnishes — Evaluation of degradation of paint coatings — Designation of in- tensity, quantity and size of common types of defect — Part 4: Designation of degree of cracking. 1SO 4628-5:1982, Paints and vamishes — Evaluation of degradation of paint coatings — Designation of in- tensity, quantity and size of common types of defect — Part 8: Designation of degree of fieking. ISO 8501-1:1988, Preparation of stee! substrates be- fore application of paints and related products — Vis- ual assessment of surface cleanliness — Part 1: Rust grades and preparation grades of uncoated steé! sub- strates and of stee! substrates after overall removal of previous coatings. ISO 8501-2:—, Preparation of stee! substrates before application of paints and related products — Visual assessment of surface cleanliness — Part 2: Prepa- ration grades of previously coated steel substrates, after localized removal of previous coatings. ISO/TR 8502-1:1981, Preparation of stee! substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 1: Field test for soluble iron corrosion products. ISO 8502-2:1992, Preparation of stee! substrates be- fore application ‘of paints and related products — Tests for the assessment of surface cleanliness — Part 2: Laboratory determination of chloride on cleaned surfaces.ISO 8504-1:1992(E) ISO 8502-3:1992, Preparation of steel substrates be- fore application of paints and related products — Tests for the assessment of surface cleanliness — Part 3: Assessment of dust on steel surfaces pre- pared for painting (pressure-sensitive tape method). 1SO 8502-4—, Preparation of stee! substrates before application of paint and related products — Tests for the assessment of surface cleanliness — Part 4: Guidence on the estimation of the probability of condensation prior to paint application. ISO 8503-1:1988, Preparation of stee! substrates be- fore application of paints and related products — Sur- face roughness characteristics of blast-cleaned steel substrates — Part 1: Specifications and definitions for ISO surface profile comparators for the assessment of abrasive blast-cleaned surfaces. 10 8503-2:1988, Preparation of steel! substrates be- fore application of paints and related products — Sur- face roughness characteristics of blast-cleaned steel substrates — Part 2: Method for the grading of sur- face profile of abrasive blast-cleaned steel — Comparator procedure. 1SO 8503-3:1988, Preparation of steel substrates be- fore application of paints and related products — Sur- face roughness characteristics of blast-cleaned stee! substrates — Part 3: Method for the calibration of ISO surface profile comparators and for the determi- nation of surface profile — Focusing microscope pro- cedure. ISO 8503-4:1988, Preparation of steel substrates be- fore application of paints and related products — Sur- face roughness characteristics of blast-cleaned steel substrates — Part 4: Method for the calibration of ISO surface profile comparators and for the determi- nation of surface profile — Stylus instrument pro- cedure. 1SO 8504-2:1992, Preparation of steel substrates be- fore application of paints and related products — Sur- face preparation methods — Part 2: Abrasive blast-cleaning. 3 General When selecting 2 surface preparation method, it is necessary to consider the preparation grade required to give @ level of surface cleanliness and, if required, a surface profile (roughness), such as coarse, medium or fine (see ISO 8503-1 and ISO 8503-2}, appropriate to the coating system to be applied to the steel sur- face. Since the cost of surface preparation is usvelly in proportion to the level of cleanliness, a preparation - grade appropriate to the purpose and type of coating system oF a coating system appropriate to the prepa- ration grade which can be achieved should be chosen, Firms carrying out surface preparation work should have the personnel and technical knowledge of the processes involved to enable them to carry out the work adequately. All relevant health and safety regu- lations shall be observed. The surfaces to be treated should preferably be readily accessible and sufficiently illuminated. All surface preparation work should be property supervised and inspected. Details regarding the preliminary treatment of welds, the removal of weld spatter and removal of burrs and other sharp edges should be provided. These meas- ures should normally be taken in connection with the manufacturing process before the surface prepara tion. If the specified preparation grade has not been achieved by the preparation method selected or when ‘the condition of the prepared surface has sub- sequently changed before the application of the coat- ing system, relevant parts of the procedure should be repeated so as to obtain the specified preparation grade. 4 Con prepared ion of the surface to be 4.1 Assessment of the surface condition As the cost of surface preparation is significantly in- fluenced by the condition of the surface to be pre- pared, information as given in a) or b) below should be available before particular surface preparation methods and preparation grades are specified. The rust grade assessed in accordance with ISO 8501-1 will determine which representative photographic example(s) is (are) to be used in accordance with ISO 8501-1 or ISO 8501-2. 2) for uncoated surfaces — the type of steel (including special treatments that influence the surface preparation, for ex- ampie cold-rolling processes) and the thickness of the steel; — the worst rust grade, assessed in accordance with ISO 8501-1, that is evident, together with any relevant supplementary details (for exam- ple “rust grade D with heavy rust layers"); supplementary details conceming, for example, chemical andjor other contaminants, b) for coated surfaces — the type (for example type of binder and pigment), approximate film thickness, condition and age of the coating or coating system;— the degree of rusting assessed in accordance with ISO 4628-3, together with any relevant supplementary details on apparent underrust; — the degree of blistering assessed in accord- ance with ISO 4628-2; — the degree of cracking assessed in accordance with ISO 4628-4; — the degree of flaking assessed in accordance with ISO 4628.5; — supplementary details concerning, for example, adhesion and chemical andjor other contami- rants. 4.2. Influence of on-site environmental In order to hold down the cost of surface preparation and because of possible severe contamination by corrosion-stimulating substances that are difficult to remove, storage of unprotected steel in industrial or matine ‘environments should be avoided. As far as possible, surface preparation should take place when rust grade A or A to B as defined by ISO 8501-1 is present, followed by application of suitable priming paints as soon as possible. No surface preparation work using dry or moisture- injection (see ISO 8504-2) blast-cleaning methods or other dry surface preparation methods should be car- ried out'on site during rainfall or other precipitation. To minimize condensation, the temperature of the surface being prepared should be higher than the dew point of the surrounding air. If the work has to be continued even under unfavourable conditions, it is essential to take special precautions such as working under a cover, enclosing in a tent, warming the sur face andjor drying the air (see ISO 8502-4) ‘Surface preperation work in areas where there is a fire ‘or explosion hazard requires special precautions (for ‘example low-spark, electrical-grounding or flamefree procedures). 4.3 Removal of contaminants Oil, grease, dirt and similar contaminants shall be re- moved prior to surface preparation using the selected method. In addition, prior removal of heavy, firmly adhering rust and mill scale by suitable manual or mechanical techniques may be necessary. If specified or agreed, soluble salts may also be re- moved, using other techniques, prior to andjor after application of the selected surface preparation method. ISO 8504-1:1992(E) 5 Selection of the surface preparation method The selection of the method to be used for the prep- aration of a given surface will depend on — the surface condition (see clause 4 and ISO 8502 and ISO 8503); — practicability (for example operating conditions; target dates; and health, safety and environmental considerations such as evolution of dust, amount ‘of water required and flame application); — whether the complete surface or only parts of it are to be prepared; — the specified or required preparation grade; — the coating system to be applied; — economic considerations; — particular requirements with regard to operating conditions or the required result of the surface preparation procedure (for example surface profile or removal of soluble salts) 6 Selection of the preparation grade The selection of the preparation grade for a given ‘surface will depend on — the surface condition (see clause 4 and ISO 8502 and ISO 8503); — the coating system to be applied; — the corrosivity of the environment to which the coated surface will be exposed; — whether the complete surface or only parts of it are to be prepared; — the practicability of the surface preparation method associated with the preparation grade; — economic considerations. Normally the preparation grades specified in ISO 8501-1 and ISO 8501-2 are used. Other prepara- tion grades, defined either by special reference specimens or by reference areas that are part of the object to be treated, can be used by agreement be- tween the interested parties. If reference areas are agreed, these should be either effectively protected against change or photographed.1SO 8504-1:1992(E) Preperation grades corresponding to the highest de- gree of surface cleanliness, for example Sa 3 as de- fined in ISO 8501-1, should be specified only when a) they are required by the surface condition (for ex- ample considerable amount of corrosive contami- ants), by the intended coating system and/or by the corrosivity of the environment for which the coated surface is intended and 'b) the conditions for achieving and maintaining the Preparation grade (for example dry and clean air) can be met. The highest degree of surface cleanliness may also bbe justified when the maintenance intervals are pro longed, thus reducing costs of later maintenance work (for example costs for scaffold work or pro- duction shut-down). 7 Assessment of the prepared surface ‘The appearance of the prepered surface depends on — the condition of the surface prior to treatment; — the type of steel; — the surface preparation method, including the tool ‘or material (for example blast-cleaning abrasive) used. All prepared surfaces should be assessed in accord- ance with ISO 8501-1 or ISO 8501-2. If specified or agreed, the surfaces should additionally be assessed in accordance with ISO/TR&B02-1,, 1$0.8502-2 and ISO 8503-2.ISO 8504-1:1992(E) UDC 667.648.1:669.14:621.7.02 Descriptors: paints, verishes, substrates, stool products, surfece treatment, cleaning, goneralies Price based on 4 pages