1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 9224:2012Corrosion of metals and alloys Corrosivity of atmospheres Guiding values for the corrosivity categoriesBS EN ISO 9224:2012 BRITISH STANDARDNational forewordThi
2、s British Standard is the UK implementation of EN ISO 9224:2012. Together with BS EN ISO 9223:2011, BS EN ISO 9225:2011, and BS EN ISO 9226:2011, it supersedes BS EN 12500:2000, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C o m m i t t e e I S E / N
3、F E / 8 , C o r r o s i o n o f m e t a l s a n d a l l o y s .A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.
4、 The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 69029 7 ICS 77.060 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 2
5、9 February 2012.Amendments issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 9224 February 2012 ICS 77.060 Supersedes EN 12500:2000English Version Corrosion of metals and alloys - Corrosivity of atmospheres - Guiding values for the corrosivi
6、ty categories (ISO 9224:2012) Corrosion des mtaux et alliages - Corrosivit des atmosphres - Valeurs de rfrence relatives aux classes de corrosivit (ISO 9224:2012) Korrosion von Metallen und Legierungen - Korrosivitt von Atmospren - Anhaltswerte fr die Korrosivittskategorien (ISO 9224:2012) This Euro
7、pean Standard was approved by CEN on 22 January 2012. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references c
8、oncerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member
9、 into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, I
10、reland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Aven
11、ue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 9224:2012: EBS EN ISO 9224:2012 EN ISO 9224:2012 (E) 3 Foreword This document (EN ISO 9224:2012) has been prepared by Technical Committee ISO/TC
12、 156 “Corrosion of metals and alloys“ in collaboration with Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endors
13、ement, at the latest by August 2012, and conflicting national standards shall be withdrawn at the latest by August 2012. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identify
14、ing any or all such patent rights. This document supersedes EN 12500:2000. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, De
15、nmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 9224:2012 has be
16、en approved by CEN as a EN ISO 9224:2012 without any modification. BS EN ISO 9224:2012ISO 9224:2012(E) ISO 2012 All rights reserved iiiContents Page Foreword iv Introduction . v 1 Scope 1 2 Normative references 1 3 Terms and definitions . 1 4 Principle . 2 5 Prediction of corrosion attack after exte
17、nded exposure . 2 6 Specific criteria for calculation of corrosion rates of structural metals 3 6.1 Steels 3 6.2 Zinc materials 4 6.3 Copper alloys . 4 6.4 Aluminium alloys . 4 7 Long-term exposures 4 Annex A (informative) Example of maximum corrosion attack after extended exposures for corrosivity
18、categories . 7 Annex B (informative) Average initial corrosion rates and average steady corrosion rates in intervals relative to classified corrosivity categories 9 Annex C (informative) Prediction of corrosion attack of steels with regard to steel composition 10 Bibliography 12 BS EN ISO 9224:2012I
19、SO 9224:2012(E) iv ISO 2012 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each me
20、mber 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 E
21、lectrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards ad
22、opted 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. Attention is drawn to the possibility that some of the elements of this document may be the subject of pa
23、tent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 9224 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys. This second edition cancels and replaces the first edition (ISO 9224:1992), which has been technically revised. BS EN
24、 ISO 9224:2012ISO 9224:2012(E) ISO 2012 All rights reserved vIntroduction The “corrosivity category” established in ISO 9223 is a general term suitable for engineering purposes, which describes the corrosion properties of atmospheres based on current knowledge of atmospheric corrosion. Guiding value
25、s of corrosion attack can be used to predict the extent of corrosion attack in long-term exposures based on measurements of corrosion attack in the first-year exposure to the outdoor atmosphere in question. These values can also be used to determine conservative estimates of corrosion attack based o
26、n environmental information or corrosivity category estimates as shown in ISO 9223. Corrosion attack estimates obtained by using the methods in this International Standard can be used to predict the useful life of metallic components and, in some cases, of metallic coatings exposed to outdoor atmosp
27、heres covered by ISO 9223. The corrosion attack results can also be used to determine whether or not protective measures, such as coatings, are required to achieve desired product lives. Other uses include the selection of construction materials for outdoor atmospheric service. Guiding values of cor
28、rosion can be used as information for the selection of a protection method against atmospheric corrosion according to ISO 11303. The guiding values in this International Standard are based on a large number of exposures in many locations throughout the world. However, the procedure used in this Inte
29、rnational Standard cannot possibly cover all the situations in natural environments and service conditions which can occur. In particular, situations that result in significant changes in the environment can cause major increases or decreases in corrosion rates. Users of this International Standard
30、are cautioned to consult with qualified experts in the field of outdoor atmospheric corrosion in cases where localized corrosion can be more important than general attack. The specific issues of galvanic (bi-metallic) corrosion, pitting corrosion, crevice corrosion, environmental cracking and corros
31、ion product wedging are not addressed in this International Standard. BS EN ISO 9224:2012BS EN ISO 9224:2012INTERNATIONAL STANDARD ISO 9224:2012(E) ISO 2012 All rights reserved 1Corrosion of metals and alloys Corrosivity of atmospheres Guiding values for the corrosivity categories 1 Scope This Inter
32、national Standard specifies guiding values of corrosion attack for metals and alloys exposed to natural outdoor atmospheres for exposures greater than one year. This International Standard is intended to be used in conjunction with ISO 9223. Guiding corrosion values for standard structural materials
33、 can be used for engineering calculations. The guiding corrosion values specify the technical content of each of the individual corrosivity categories for these standard metals. Annex A provides examples of calculated maximum corrosion attack after extended exposure (up to 20 years) for six standard
34、ized corrosivity categories. Annex B provides presumed average initial and steady-state corrosion rates of standard metals in intervals relative to six standardized corrosivity categories. Annex C provides the calculation procedure for corrosion attack of steels in regard to their composition. 2 Nor
35、mative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 8044, Corrosion of metals a
36、nd alloys Basic terms and definitions ISO 9223, Corrosion of metals and alloys Corrosivity of atmospheres Classification, determination and estimation 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 8044 and the following apply. 3.1 guiding corrosion
37、 value corrosion rates, mass loss, penetration or other corrosion characteristics expressing the expected corrosive action of the atmospheric environment of a given corrosivity category towards standard metals 3.2 corrosion rate after extended exposure corrosion rate after exposures longer than one
38、year BS EN ISO 9224:2012ISO 9224:2012(E) 2 ISO 2012 All rights reserved3.3 average corrosion rate ravyearly corrosion rate calculated as an average value for the first 10 years of atmospheric exposure of a metal 3.4 steady-state corrosion rate rlinyearly corrosion rate derived from a long-term atmos
39、pheric exposure of a metal, not including the initial period NOTE For the purposes of this International Standard, the corrosion rate after 10 years of exposure is considered constant. 4 Principle The corrosion rate of metals and alloys exposed to natural outdoor atmospheres is not constant with exp
40、osure time. For most metals and alloys, it decreases with exposure time because of the accumulation of corrosion products on the surface of the metal exposed. The progress of attack on engineering metals and alloys is usually observed to be linear when the total damage is plotted against exposure ti
41、me on logarithmic coordinates. This relationship indicates that the total attack, D, expressed either as mass loss per unit area or penetration depth, may be given as: D = rcorrtb(1) where t is the exposure time, expressed in years; rcorris the corrosion rate experienced in the first year, expressed
42、 in grams per square metre per year g/(m2a) or micrometres per year (m/a), in accordance with ISO 9223; b is the metal-environment-specific time exponent, usually less than 1. 5 Prediction of corrosion attack after extended exposure This procedure should be used in cases where the extent of corrosio
43、n attack in the first year is available or can be estimated by the procedures in ISO 9223, and the desire is to predict the extent of attack after an extended exposure. The attack prediction is calculated by substituting the values in Equation (1). An appropriate b value is selected or calculated ac
44、cording to Clause 7. In cases where long-term metal loss data are available, use the b value from this data. In cases where the detailed composition of the metal is not known, select the B1 value from Table 2 for the metal or alloy in question. This is the b value to be used in Equation (1). The B1
45、values were taken as the average time exponents from regression analyses of the flat panel long-term results of the ISO CORRAG atmospheric exposure programme1. NOTE It is necessary to distinguish between metal-environment-specific time exponent, b, in Equation (1), estimated from exposure data, and
46、B1 and B2 values assumed or calculated from the ISO CORRAG programme as generalized b values. Table 3 contains values of the function tbfor time values up to 100 years with the B1 exponents to simplify the calculations. However, it is possible for Equation (1) not to apply to exposures beyond 20 yea
47、rs (see Clause 7 below for a discussion of long-term exposures). BS EN ISO 9224:2012ISO 9224:2012(E) ISO 2012 All rights reserved 3In cases where it is important to estimate a conservative upper limit of corrosion attack after an extended exposure, the b value used in Equation (1) should be increase
48、d to account for uncertainties in the data. One way to do this is to add two standard deviations to the average value to obtain a value at the upper 95 % confidence level. For the four metals shown in Table 2, the standard deviations of the b values1are: Carbon steel: 0,026 0 Zinc: 0,030 0 Copper: 0
49、,029 5 Aluminium: 0,039 5 NOTE Estimation of a conservative upper limit of corrosion attack after an extended exposure is based on uncertainties in b. This estimation does not take into account uncertainties in rcorr, which are defined in ISO 9223. The B2 values in Table 2 include the two standard deviation additions and may be used where an upper limit of corrosion attack is desired when using the flat panel data from the ISO CORRAG programme. Table 3 also provides calculated values for the function, tb, up to
