© ISO 2017 Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 4 Guidance on the estimation of the probability of[.]
INTERNATIONAL STANDARD ISO 8502-4 Second edition 2017-01 Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 4: Guidance on the estimation of the probability of condensation prior to paint application Préparation des subjectiles d’acier avant application de peintures et de produits assimilés — Essais pour apprécier la propreté d’une surface — Partie 4: Principes directeurs pour l’estimation de la probabilité de condensation avant application de peinture Reference number ISO 8502-4:2017(E) © ISO 2017 ISO 8502-4:2017(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 8502-4:2017(E) Contents Page Foreword iv Introduction vi Scope Normative references Probability of condensation Instruments Procedure Test report Annex A (informative) Table for determination of dew-point Bibliography 26 © ISO 2017 – All rights reserved iii ISO 8502-4:2017(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 second edition cancels and replaces the first edition (ISO 8502-4:1993), which has been technically revised with the following changes: a) normative references have been updated; b) mercury thermometer has been replaced by thermometer in Clause a); c) d) e) f) additional information is given in the note to Clause b); combined instrument described in Clause d); notes on instrument properties have been added in Clause 4; in 5.2, “at a given atmospheric pressure” has been added to read “Their parameters are air temperature and relative humidity at a given atmospheric pressure”; g) in 5.3 , it has been added that non-contact thermometers should not be used; h) 5.4 has been changed to account for the definition of high and low risk of condensation given in Clause ; i) description of the procedure with combined instruments has been added in 5.5 j) a re ference to the formula used in Annex A has been added 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) © ISO 2017 – All rights reserved ISO 85 02 -4: 01 7(E) — — — — — — 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 v ISO 8502-4:2017(E) Introduction T he p er formance o f pro te c tive co ati ngs o f p a i nt and rel ate 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 ur face i m me d i ately prior to p nti ng T he pri ncip a l known to i n fluence th i s p er forma nce are as fac tors that a re fol lows: a) presence of rust and mill scale; b) presence of surface contaminants, including salts, dust, oils and greases; 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 Standard s have b e en prep a re 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 c i fie d level s o f cle a n 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 u r face Neither they contai n re com mendation s qua l ity re qui rements for for the s ur face s p e c i fic s ituation s even though s ur face qua l ity c an have 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 tanda rd s and co de s o f prac tice I t wi l l b e ne ce s s ar y for the u s ers o f the s e I nternationa l Stand ard 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 and — 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 a ni ng pro ce du re s p e c i 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: — ISO 8501 on visual assessment of surface cleanliness; — ISO 8502 on tests for the assessment of surface cleanliness; — I S O 03 on s ur face rough ne s s ch arac teri s tics o f bl as t- cle ane d s te el s ub s trate s; — ISO 8504 on surface preparation methods Each of these International Standards is in turn divided into separate parts S ome p a i nts ( but no t a l l) re qu i re d r y s u r face s when b ei ng appl ie d to s te el s tr uc tu re s T h i n fi l m s o f conden s e d water on s te el s u r face s are mo s tly i nvi s ible I t i s there fore i mp or ta nt to h ave a me tho d b y wh ich the prob abi l ity o f conden s ation c an b e e s ti mate d prior to the appl ic ation o f p nt vi © ISO 2017 – All rights reserved INTERNATIONAL STANDARD ISO 8502-4:2017(E) Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 4: Guidance on the estimation of the probability of condensation prior to paint application Scope This part of ISO 8502 give s gu idance on the e s ti mation o f the prob abi l ity o f conden s ation on a s ur face to b e p nte d I t may b e u s e d to e s tabl i sh whe ther cond ition s at the j ob s ite are s uitable for p nti ng or no t Normative references T he fol lowi ng i nd i s p en s able c u ments , i n whole or i n p ar t, are normatively re ference d i n th i s c u ment a nd are for its appl ic ation For date d re ference s , on ly the e d ition cite d appl ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c u ment (i nclud i ng any amend ments) appl ie s ISO 8601, Data elements and interchange formats — Information interchange — Representation of dates and times Probability of condensation T he relative hu m id ity o f the a i r a nd the s te el s u r face temp eratu re are the b a s i s for the e s ti mation o f the prob abi l ity o f conden s ation, but there i s no s i mple ru le to employ T he s ituation i s comple x b e c au s e there a re a mu ltitude of fac tors wh ich have moisture, such as — heat conductance of the structure, — solar radiation on the surface, a n i n fluence on the — flow o f a mbient a i r arou nd the s truc ture, and — contam i nation b y hygro s copic s ub s ta nce s on the s ur face T he s e fac tors conden s ation and evap oration o f s ome ti me s provoke we tti ng or prevent d r yi ng lo c a l ly on the s u r face, e g where the s ur face temp eratu re rema i n s low or tend s to fa l l due to he at lo s s e s or where the r b e come s qu ickly s atu rate d due to re duce d venti lation Natu l ly, the s ame fac tors s ome ti me s have the opp o s ite e ffe c t T here fore, a ny te s t re s u lts shou ld b e i nterpre te d with the gre ate s t c are Un le s s o ther wi s e agre e d , the s te el s ur face temp eratu re s hou ld genera l ly b e at le a s t ° C ab ove the dew- point when paints are used NO TE Fo r p a i nts th at a re tolera nt to mo i s tu re on the s u r face , a temp eratu re d i fference le s s th a n ° C m ight be acceptable O ther temp eratu re d i fference s may b e s p e c i fie d b y the p nt manu fac tu rer or agre e d b y the i ntere s te d parties © ISO 2017 – All rights reserved ISO 8502-4:2017(E) If the difference between the surface temperature and the dew-point is below or will fall below the required and/or agreed minimum, the probability o f condensation should be considered as being “high” I f the di fference is above and will remain above the required and/or agreed minimum, the probability of condensation should be considered as being “low” It is important to judge whether a temperature drop, su fficient to cause condensation, is likely to occur during the critical period Table may be used to help with this determination I f the relative humidity is 85 % or higher, then painting should be judged critically as the dew-point is a maximum o f 2,5 °C away I f the relative humidity is high (92 % or dew-point 1,3 °C away), painting should only be considered i f conditions can be confidently expected to remain static or improve during the application and drying period NOTE This period is usually approximately h I f the relative humidity is apparently satis factory (for example, 80 % or dew-point 3,4 °C away), the environmental conditions over an appropriate time period ahead, often about h, should still be considered in order to ascertain that dew conditions will not occur Instruments The following instruments should be used, although instruments other than those described may be used provided that they have an equivalent or greater accuracy a) For air temperature measurements, thermometers accurate to ±0,5 °C b) For air humidity measurements, any o f the following instruments 1) Aspirated psychrometers and whirling (sling) hygrometers, including tables for calculation o f humidity (see ISO 4677-1 and ISO 4677-2, respectively), accurate to ±3 % RH NOTE The aspirated psychrometer is the re ference instrument type according to the World Meteorological Organization (WMO) 2) Digital electronic hygrometers based on measurement o f capacitance change o f polymer films, accurate to ±3 % RH and capable o f operating at any relative humidity in the range % RH to 100 % RH and at any temperature in the range −40 °C to +80 °C 3) Digital electronic hygrometers based on measuring the resistance change in a salt bridge, accurate to ±2 % RH and capable o f operating at any relative humidity in the range % RH to 97 % RH and at any temperature in the range °C to 70 °C Due to the sensitivity to hysteresis, electronic dew point gauges should be handled according to manu facturer specifications and the probability for hysteresis should be prevented to maintain correct results The probe should, for example, not be exposed to large temperature/humidity variations Condensation on the sensor sur face may give o ffset reading in the order o f 10 %, for some sensor types lasting for days NOTE Hygrometers are sensitive to contamination; salts or other substances adsorbing moisture will NOTE Hygrometers require calibration; some types, as sensors using a salt bridge, more o ften than others cause erroneous readings c) For sur face temperature measurements, digital electronic thermometers, accurate to ±0,5 °C Magnetic sur face thermometers may be used provided that they have the required accuracy and are le ft on the sur face for su fficient time to reach the sur face temperature © ISO 2017 – All rights reserved ISO 8502-4:2017(E) d) D igita l ele c tronic i n s tru ments me a s u ri ng r temp eratu re, s u r face temp eratu re a nd hu m id ity, capable of calculating the dew point, as well as the difference between the air temperature and the dew point Procedure Using the instruments described in Clause a) and Clause b), measure the air temperature to the 5.1 neares t , °C and the relative humidity Calculate the dew-point, which is a logarithmic function of the vapour pressure at the actual temperature There are tables or charts from which the dew-point can be determined Their parameters Annex A f f 5.2 are air temp erature and relative humidity at a given atmo s p heric p res s ure S uch a tab le is given in C o mmercial dew- p o int calculato rs o s u ficient accuracy may als o b e us ed Table — Temperature drop needed for condensation to occur, as a function of the relative humidity 98 Relative humidity, % Temperature drop , ° C NO TE 0, T he fi g u re s a re me a n va lue s fi g u re s c a n b e o b ta i ne d fro m 95 0,8 Annex A fo r a i r temp eratu re s 92 1,3 fro m 90 1,6 85 2,5 80 ,4 ° C to ° C Fo r a g i ve n a i r temp eratu re , mo re acc u rate Using the instrument described in Clause c), measure the steel surface temperature Take at of the surface and adopt the lowest measured f temperature in calculating the dew point Non-contact thermometers (IR-thermometers) should not be used to measure surface temperature due to interference with the surrounding air 5.3 leas t o ne temp erature meas urement When s ele c ti ng lo c ation s for o r every m temp eratu re me a s urements , a ny vari ation i n the th ickne s s o f the s te el a nd the effect of shade should be considered NO TE S ome d igita l ele c tron ic hygrome ters a l s o me a s u re the a i r temp eratu re a nd c a lc u l ate the dew-p oi nt temp eratu re autom atic a l l y 5.4 Estimate the minimum surface temperature (above the dew-point) that is needed to obtain a “low” risk of condensation under the prevailing environmental conditions, see C laus e If using a combined instrument described in Clause d), points 5.1 to 5.4 following procedure: Read the dew point, calculate or read the difference between the dew point and the surface temperature and check if risks for condensation are considered “low” or “high”, see 5.5 s hall b e rep laced by the C laus e Test report The test report shall include the following: a) a reference to this part of ISO 8502, i.e ISO 8502-4; b) c) d) e) f) the date o f c a rr yi ng out the me as u rements (i nclud i ng the day and hou r) , expre s s e d i n accorda nce with ISO 8601; a description of the instruments used; the calculated dew-point; the measured steel surface temperature; the difference between the steel surface temperature and the dew-point; © ISO 2017 – All rights reserved ISO 85 02 -4: 01 7(E) g) the minimum temperature difference needed to avoid condensation; fe atu re s h) any u nu s ua l i) an e s ti mate o f the prob abi l ity o f conden s ation a s b ei ng “h igh” or “low” (anoma l ie s) ob s er ve d du ri ng the te s t; © ISO 2017 – All rights reserved ISO 8502-4:2017(E) Table A.1 (continued) , Relative humidity RH (%) 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 14 Air temperature t 20 (° C ) 21 22 23 24 25 26 27 28 29 - 7, - ,9 -3 , -3 , -3 , -3 4, -3 4, -3 ,4 -3 , -3 , -3 , -3 , -2 , -2 , -2 , -2 , -2 , -20,6 -18,5 -16,7 -15,2 -25,6 -22,5 -19,9 -17,8 -16,0 -14,4 -1 , -1 , -2 , -2 , -12,4 -6,5 -5,7 -5,0 -11,7 -10,5 -9,4 -8,4 -7,4 -6,5 -5,7 -4,9 -4,2 - 4, -3 ,4 -1 , -10,2 -9,2 -8,2 -7, -3 , -2,9 -2 , -1,7 -1,1 -0,6 -2,8 -2,1 -1,5 -0,9 -0, 0, -25,0 -21,8 -19,2 -17,1 -1 , -1 , -12,2 -10,9 -9,7 -8,6 -7,6 -6,6 -5,8 -4,9 -4,1 -3 ,4 -2,6 -1,9 -1 , -0,6 0,0 0,5 1,1 -28,7 -21,1 -18,5 -16,4 -14,6 -12,9 -11,5 -10,2 -9,0 -7,9 -6,8 -5,9 -5,0 -4,1 -3 , -2,5 -1,8 -1,1 -0,5 0,2 0,8 1,4 2,0 -28,0 -20,4 -17,8 -15,7 -1 , -12,2 -10,7 -9,4 -8,2 -7,1 -6,0 -5,1 -4,2 -3 , -2,5 -1,7 -1,0 -0,3 0,4 1,0 1,6 2,2 2,8 -27,4 -19,7 -17,1 -15,0 -1 , -11,5 -10,0 -8,6 -7,4 -6,3 -5 , - 4, -3 ,4 -2,5 -1,7 -0,9 -0,2 0,5 1,2 1,8 2,5 ,1 ,6 -26,8 -19,0 -16,4 -14,2 -12,4 -10,7 -9,2 -7,9 -6,7 -5,5 -4,5 -3 , -2,6 -1,7 -0,9 -0,1 0,6 1,3 2,0 2,7 3,3 ,9 4,5 -26,1 -21,7 -18,4 -15,7 -1 , -11,6 -10,0 -8,5 -7,1 -5,9 -4,8 -3 ,7 -2,7 -1,8 -0,9 -0,1 0,7 1,4 2,2 2,8 3,5 4,1 4,7 5,3 -25,5 -21,0 -17,7 -15,0 -12,8 -10,9 -9,2 -7,7 -6,4 -5,1 -4,0 -2,9 -1,9 -1,0 -0,1 0,7 1,5 2,3 ,0 ,7 4, 5,0 5,6 6,2 -24,9 -2 , -17,0 -14 , -12,1 -10,2 -8,5 -7,0 -5,6 -4,4 -3 , -2,1 -1,1 -0,2 0,7 1,5 ,3 ,1 3,8 4,5 5,2 5,8 6,4 7,0 © ISO 2017 – All rights reserved