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© ISO 2017 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[.]
INTERNATIONAL STANDARD ISO 8502-2 Third edition 2017-01 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 Préparation des subjectiles d’acier avant application de peintures et de produits assimilés — Essais pour apprécier la propreté d’une surface — Partie 2: Recherche en laboratoire des chlorures sur les surfaces nettoyées Reference number ISO 8502-2:2017(E) © ISO 2017 ISO 8502-2:2017(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2017, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2017 – All rights reserved ISO 8502-2:2017(E) Contents Page Foreword iv Introduction v Scope Normative references Principle Reagents and materials Apparatus Procedure Expression of results Test report Annex A (informative) Determination of chloride by coulometric titration Bibliography © ISO 2017 – All rights reserved iii ISO 8502-2:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f 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 non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso org/patents) Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html 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 o f analysis methods from other standards have been added; c) the coulometric method has been added and briefly described in an in formative annex; d) the formula in Clause has been replaced by Formula (1) transforming chloride concentration in a solution to amount o f chloride on the sur face; 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: — — — — — — — — iv 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 © ISO 2017 – All rights reserved ISO 8502-2:2017(E) Introduction T he p er formance o f pro te c tive co ati ngs o f p nt a nd relate d pro duc ts appl ie d to s te el i s s ign i fic antly a ffe c te d b y the s tate o f the s te el s u r face i m me d iately prior to p a i nti ng T he pri nc ip a l known to i n fluence th i s p er formance are as fac tors that are fol lows: a) pre s ence o f r u s t and m i l l s c a le; b) pre s ence o f s u r face conta m i nants , i nclud i ng s a lts , du s t, oi l s and gre as e s; c) s u r face pro fi le T he I S O 01 , I S O 02 and I S O s erie s o f I nternationa l Sta ndard s have b e en prep are d 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 s p e ci fie d level s o f cle an l i ne s s These series of International Standards not contain recommendations for the protective coating s ys tem s to b e appl ie d to the s te el s ur face Neither they conta i n re com mendation s qua l ity re qu i rements for for the s u r face s p e ci fic s ituation s even though s u r face qua l ity c an h ave a d i re c t i n fluence on the choice of protective coating to be applied and on its performance Such recommendations are found i n o ther c u ments s uch a s nationa l s tandard s a nd co de s o f prac tice I t wi l l b e ne ce s s a r y for the u s ers o f the s e I nternationa l Standard s to en s u re that the qua l itie s s p e c i fie d are — compatible and appropriate both for the environmental conditions to which the steel will be exposed a nd — for the pro te c tive co ati ng s ys tem to b e u s e d, and with i n the c ap abi l ity o f the cle an i ng pro ce dure s p e ci fie d 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: — I S O 01 on vi s ua l as s e s s ment o f s u r face cle an l i ne s s; — I S O 02 on te s ts — I S O on s u r face rough ne s s charac teri s tics o f bla s t- cle a ne d s te el s ub s trate s; for the as s e s s ment o f s u r face cle an l i ne s s; — ISO 8504 on surface preparation methods Each of these International Standards is in turn divided into separate parts This part of ISO 8502 de s c rib e s a me tho d for the a s s e s s ment o f ch loride - conta i ni ng s a lts th at are re ad i ly s oluble i n water a nd are pre s ent on a s te el s u r face Ru s te d s te el s ub s trate s , p a r tic u larly o f ru s t grade s C or D (s e e I S O 01-1) , even when bla s t cle a ne d to prep aration grade S a (s e e I S O 01-1) c a n s ti l l b e conta m i nate d b y s oluble salts and corrosion products These compounds are almost colourless and are localized at the lowest p oi nt o f the r u s t pits I f they are no t remove d prior to p a i nti ng , chem ic a l re ac tion s c a n re s u lt i n large acc u mu l ation s o f r u s t th at de s troy the ad he s ion b e twe en the s ub s trate a nd the appl ie d pro te c tive co ati ng E ven i f the s a lt i s re ad i ly s oluble i n water, it i s o ften i mp o s s ible to remove it comple tely from the s ur face b y a s i mple was h i ng s uch as th at de s c rib e d i n th i s pro ce du re T he me tho d e s no t there fore 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 © ISO 2017 – All rights reserved v INTERNATIONAL STANDARD ISO 8502-2:2017(E) 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 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 sur face The method is also applicable to previously coated sur faces This part o f ISO 8502 includes a method, applicable in the field or in the laboratory, for washing o ff the sur face while several methods are re ferred to for chloride analyses NOTE ISO 8502-5 describes a field test for the determination o f chloride on a sur face NOTE The precision o f the method is limited by both the accuracy o f the selected method o f analyses and by uncertainties in the sampling procedure The extraction method might not take all the water soluble material off the surface due to — soluble material hiding in crevices, under folds of metal or at the bottom of pits, and — soluble material hiding under corrosion layers, passivation layers, inhibitors, oil, grease, or other non-visible thin films as these boundary layers can prevent contact with the underlying salt for its removal NOTE The per formance o f a paint system is a ffected by the amount o f soluble chloride remaining on the surface The acceptable level of this contamination is related to the service conditions For further information regarding levels o f water-soluble salt contamination, see ISO/TR 15235 Normative references The following documents, in whole or in part, are normatively re ferenced in this document and are indispensable for its application For dated re ferences, only the edition cited applies For undated re ferences, the latest edition o f the re ferenced document (including any amendments) applies ISO 3696, Water for analytical laboratory use — Specification and test methods Principle A defined area o f the steel sur face is washed with a known volume o f water and assessment o f chloride concentration in the wash water is then carried out using instrumental methods Reagents and materials During the analysis, use only reagents o f recognized analytical grade 4.1 Water, forming to the requirements o f grade o f ISO 3696 4.2 Chalk, essentially chloride- free, or other suitable means for marking the test area 4.3 Absorbent cotton pads (cotton wool) , of mass g to 1,5 g © ISO 2017 – All rights reserved ISO 8502-2:2017(E) Apparatus 5.1 Ruler 5.2 Metal spatula or knife 5.3 Gloves , of plastics material 5.4 Beakers , o f capacity 250 ml 5.5 Small glass rod 5.6 Filter funnel 5.7 Filter paper, approximately 120 mm diameter 5.8 Measuring cylinder, o f capacity 50 ml 5.9 Volumetric flasks , of capacities 50 ml, 100 ml and 000 ml 5.10 Volumetric pipettes , of capacities ml and 20 ml Procedure 6.1 Washing of the surface Carry out the test at least in duplicate During the swabbing procedure, prevent accidental contamination o f the wash water by using, for example, clean plastics gloves (5.3 ) each time Mark out a test area measuring approximately 25 000 mm (for example, 250 mm × 100 mm) using the ruler (5.1) and chalk or other suitable means (4.2) Record the actual area in square millimetres Mark two beakers (5.4) A and B Pour 45 ml of water (4.1) into beaker A, using the measuring cylinder (5.8) Soak an absorbent cotton pad (4.3) in the water and thoroughly swab the test area with the pad Do not allow water to drip from the pad or run off the test area Remove the water from the surface with the absorbent cotton pad and squeeze the washings into beaker B In the case of bare steel, scrape the surface with the metal spatula or knife (5.2) until bright metal is exposed and is o f su fficient size to conduct a representative sur face retrieval or replicates the sur face condition specified immediately prior to coating Repeat the swabbing procedure with several portions of water until all the water in beaker A has been used If the cotton pad becomes worn out, use a fresh one and keep the used absorbent cotton pads The swabbing procedure should take at least 10 Filter the washings, using the filter paper (5.7 ) and the filter funnel (5.6) and collect the filtrate in the volumetric flask o f capacity 50 ml (5.9 ) Wash the used absorbent cotton pads and the filter paper with small portions of water (total ml), using beaker B and the small glass rod (5.5) Squeeze the pads and collect the washings in the flask Fill up to the mark with water NOTE An alternative method for sampling is described in ISO 8502-6 © ISO 2017 – All rights reserved ISO 8502-2:2017(E) 6.2 Wash-water analysis For the assessment of chloride concentration in the wash-water, different methods can be used dep end i ng on e qu ipment ava i lable and acc u rac y re qu i re d S ome e xample s are as — ion ch romato graphy (I S O 10 -1) ; — de te c tion me tho d o f the ion de te c tion tub e me tho d (I S O 02 -5 ) ; — ion s ele c tive ele c tro de (I S O 517 ) ; fol lows: — coulometric titration, see Annex A NOTE Both the ion detection tube method (ISO 8502-5) and the ion selective electrode (ISO 9517) require co nd ition i n g o f the wa s h-water b e fore a n a l ys e s I f a l l s a lts pre s ent i n the was h-water are s idere d to b e contai n i ng the a nion ch loride, conduc tivity me as u rement c a n b e u s e d a nd conver te d to a n as s u me d non- s p e ci fic re s u lt u s i ng I S O -9 O ther me tho d s tha n tho s e l i s te d ab ove m ight b e appropri ate T he me as u rement u ncer tai nty o f the me tho d u s e d s l l a lways b e ta ken i nto accou nt a nd rep or te d Titration i nclud i ng merc u r y or ch romate contai n i ng s ub s tance s shou ld b e avoide d due to he a lth a nd environmental hazards Expression of results Calculate the amount of chloride per unit surface area, ρA(Cl), expressed in milligrams per square metre, using Formula (1): ρA ( Cl ) = c × VA⋅ 10 (1) where c A V i s the ch loride concentration i n the was h-water, expre s s e d i n m i l l igram s p er l itre; is the surface area washed, expressed in square millimetres is the sampling volume of water, expressed in millilitres (50 ml used in the procedure of ) D i lution, e g by add i ng acid or ion s treng th adj u s tor or from add i ng a s ma l l a mount o f the s a mple to a larger volume of buffer solution (required for the ion detection tube, the ion selective electrode and f volume to be used in Formula (1) or the cou lome tric titration me tho d s , re s p e c tively) , s l l b e ta ken i nto accou nt when c a lc u l ati ng the Test report The test report shall contain at least the following information: a) a l l de tai l s ne ce s s ar y to identi fy the s u r face te s te d, i nclud i ng de ta i l s o f sh ap e and attitude (e g hori z onta l, ver tic a l , at a n angle) ; b) a re ference to th i s p ar t o f I S O 02 , i e I S O -2 ; c) the me tho d u s e d for a s s e s s i ng the ch loride concentration i n the wa s h-water; d) the results of the test, including the results of all individual determinations and their mean, expressed as indicated in Clause ; © ISO 2017 – All rights reserved ISO 85 02 -2 : 01 7(E) e) any deviation s f) any u nu s ua l from the te s t me tho d s p e ci fie d; fe atu re s (anoma l ie s) ob s er ve d du ri ng the te s t; g) date(s) of the test © ISO 2017 – All rights reserved ISO 8502-2:2017(E) Annex A (informative) Determination of chloride by coulometric titration Principle for the method: A current is passed between a cathode and a silver-containing anode placed in a buffer solution to which a portion of a reference solution with known chloride contents is added followed by the sample The chloride ions will react with the produced silver ions forming a precipitate The end point can be detected by changes in solution conductivity due to the presence o f excess silver ions in solution or by potential changes Accuracy o f the method is dependent on the system used for controlling current and the end point, the bu ffer solution and electrodes used (a ffecting the current e fficiency and solubility o f species formed), the accuracy o f the re ference solution, the di fference in chloride concentration between the re ference and the sample and the use of the instrumentation If commercial instruments are used, it is vital to follow the instrument manual, using proper buffer solutions etc © ISO 2017 – All rights reserved ISO 8502-2:2017(E) Bibliography [1] ISO 9517, Iron ores — Determination of water-soluble chloride — Ion-selective electrode method [2 ] ISO -1 , Water quality — Determination of dissolved anions by liquid chromatography of ions — Part 1: Determination of bromide, chloride, fluoride, nitrate, nitrite, phosphate and sulfate Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 5: Measurement of chloride on steel surfaces prepared for painting (ion detection tube method) [3 ] ISO [4] ISO [5] ISO 8502-9, 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 [6 ] -5 , Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 6: Extraction of soluble contaminants for analysis — The Bresle method 85 02- 6, Preparation of steel substrates before application of paints and related products — Collected information on the effect of levels of water-soluble salt contamination I S O/ T R 5 , © ISO 2017 – All rights reserved ISO 85 02 -2 : 01 7(E) ICS 25.220.10 Price based on pages © ISO 2017 – All rights reserved