BS EN 12502-2-2005 Protection of metallic materials against corrosion - Guidance on the assessment of corrosion likelihood in water distribution and storage systems - Influencing f.pdf

1、BRITISH STANDARD BS EN 12502-2:2004 Protection of metallic materials against corrosion Guidance on the assessment of corrosion likelihood in water distribution and storage systems Part 2: Influencing factors for copper and copper alloys The European Standard EN 12502-2:2004 has the status of a Briti

2、sh Standard ICS 77.060; 23.040.99; 91.140.60 BS EN 12502-2:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 19 January 2005 BSI 19 January 2005 ISBN 0 580 45297 2 National foreword This British Standard is the official English language ve

3、rsion of EN 12502-2:2004. The UK participation in its preparation was entrusted to Technical Committee ISE/NFE/8, Corrosion of metals and alloys, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The B

4、ritish Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards

5、Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the respo

6、nsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cov

7、er, the EN title page, pages 2 to 17 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12502-2 December 2004 ICS 77.060; 23

8、.040.99; 91.140.60 English version Protection of metallic materials against corrosion - Guidance on the assessment of corrosion likelihood in water distribution and storage systems - Part 2: Influencing factors for copper and copper alloys Protection des matriaux mtalliques contre la corrosion - Rec

9、ommandations pour lvaluation du risque de corrosion dans les installations de distribution et de stockage deau - Partie 2 : Facteurs considrer pour le cuivre et les alliages de cuivre Korrosionsschutz metallischer Werkstoffe - Hinweise zur Abschtzung der Korrosionswahrscheinlichkeit in Wasserverteil

10、ungs- und speichersystemen - Teil 2: Einflussfaktoren fr Kupfer und Kupferlegierungen This European Standard was approved by CEN on 22 November 2004. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status

11、of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A vers

12、ion in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Eston

13、ia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KO

14、MITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12502-2:2004: EEN 12502-2:2004 (E) 2 Contents Page Foreword3 Introduction .4 1 Scope 5 2 Normative referen

15、ces 5 3 Terms, definitions, and symbols5 3.1 Terms and definitions .5 3.2 Symbols .5 4 Types of corrosion.5 4.1 General5 4.2 Uniform corrosion7 4.3 Pitting corrosion 9 4.4 Selective corrosion12 4.5 Bimetallic corrosion 13 4.6 Erosion corrosion14 4.7 Stress corrosion 15 4.8 Corrosion fatigue.16 5 Ass

16、essment of corrosion likelihood16 Bibliography 17 EN 12502-2:2004 (E) 3 Foreword This document (EN 12502-2:2004) has been prepared by 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

17、 national standard, either by publication of an identical text or by endorsement, at the latest by June 2005, and conflicting national standards shall be withdrawn at the latest by June 2005. This standard is in five parts: Part 1: General; Part 2: Influencing factors for copper and copper alloys; P

18、art 3: Influencing factors for hot dip galvanized ferrous materials; Part 4: Influencing factors for stainless steels; Part 5: Influencing factors for cast iron, unalloyed and low alloyed steels. Together these five parts constitute a package of interrelated European Standards with a common date of

19、withdrawal (dow) of 2005-06. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Icelan

20、d, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 12502-2:2004 (E) 4 Introduction This document results mainly from investigations into and experience gained of the corrosion of copper

21、 materials in drinking water distribution systems in buildings. However, it can be applied analogously to other water systems. The corrosion likelihood of copper and copper alloys depends on the formation of a corrosion product layer that begins to form as soon as these materials come in contact wit

22、h water. The more this layer prevents ionic and electronic exchanges between the metal and water, the more protective it is and the higher the durability of the metal. Copper and copper alloy drinking water systems are, in general, resistant to corrosion damage in normal use. However, there are cert

23、ain conditions under which they will sustain corrosion damage. As a result of the complex interactions between the various influencing factors, the extent of corrosion can only be expressed in terms of likelihood. This document is a guidance document and does not set explicit rules for the use of co

24、pper and copper alloys in water systems. It can be used to minimize the likelihood of corrosion damages occurring by: assisting in designing, installing and operating systems from an anti-corrosion point of view; evaluating the need for additional corrosion protection methods for a new or existing s

25、ystem; assisting in failure analysis, when failures occur in order to prevent repeat failures occurring. However, a corrosion expert, or at least a person with technical training and experience in the corrosion field is required to give an accurate assessment of corrosion likelihood or failure analy

26、sis. EN 12502-2:2004 (E) 5 1 Scope This document gives a review of influencing factors of the corrosion likelihood of copper and copper alloys used as tubes, tanks and equipment in water distribution and storage systems as defined in EN 12502-1. 2 Normative references The following referenced docume

27、nts 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. EN 12502-1:2004, Protection of metallic materials against corrosion Guidance on

28、the assessment of corrosion likelihood in water distribution and storage systems Part 1: General. EN ISO 8044:1999, Corrosion of metals and alloys Basic terms and definitions (ISO 8044:1999). 3 Terms, definitions, and symbols 3.1 Terms and definitions For the purposes of this document, the terms and

29、 definitions given in EN ISO 8044:1999 and EN 12502-1:2004 apply. 3.2 Symbols c(HCO 3 - ) concentration of hydrogen carbonate ions in mmol/l c(SO 4 2- ) concentration of sulphate ions in mmol/lc(O 2 ) concentration of oxygen in mmol/l 4 Types of corrosion 4.1 General The most common types of corrosi

30、on are listed in EN 12502-1. Internal corrosion of copper and copper alloys in water distribution and storage systems generally leads to the build-up of layers formed by corrosion products, which can or cannot be protective. In some cases corrosion can lead to the impairment of the function of the s

31、ystem or failure because of corrosion damage (see Table 1). EN 12502-2:2004 (E) 6 Table 1 General characteristics of the different types of corrosion of copper and copper alloys Type of corrosion Uniform corrosion Pitting corrosion Erosion corrosion Selective corrosion Stress corrosion Corrosion fat

32、igue Manifestation Thin adherent layer Adherent layer Non-protective layer of corrosion products Locally perforated protective layer Protective layer destroyed mechanically or removed Dezincification Cracks perpendicular to the principal tensile stress Cracks perpendicular to tensile stress and para

33、llel to bending stress Visible corrosion products Brown/ black Cu 2O/ CuO Green Cu 2(OH) 2CO 3 a Blue Cu 2(OH) 2SO 4 green Cu 2(OH) 2CO 3 aPits covered with nodules Cu 2(OH) 2CO 3 (Type 1) aPits covered with nodules Cu 2(OH) 2SO 4 (Type 2 and microbially induced) aNo products covering the pits (Type

34、 2) aNone White products of Zn(OH) 2and/or Zn 5(OH) 6(CO 3) 2 None None Corrosion effect Negligible uniform corrosion attack Negligible uniform corrosion attack Significant uniform corrosion attack with release of corrosion products Pitting corrosion attack Profiled attack Change in colour and struc

35、ture of the alloy Cracks visible to the naked eye or under microscope Visible cracks Possible corrosion damage None None Staining of sanitary equipment Leakage Leakage Leakage, disfunction of valves Leakage Leakage aWithin a layer of Cu 2O. EN 12502-2:2004 (E) 7 The types of corrosion considered for

36、 copper and copper alloys comprise the following: uniform corrosion; pitting corrosion; selective corrosion; bimetallic corrosion; erosion corrosion; stress corrosion; corrosion fatigue. For each type of corrosion, the following influencing factors, described in EN 12502-1:2004, Table 1 and Clause 5

37、, are considered: characteristics of the metallic material; characteristics of the water; design and construction; pressure testing and commissioning; operating conditions. 4.2 Uniform corrosion 4.2.1 General Experience shows that corrosion damage to copper and copper alloys as a result of uniform c

38、orrosion is rare. The occurrence of uniform corrosion of these materials strongly depends on the properties of the surface layers that are formed. Blue-green staining of sanitary equipment and blue-green coloured water arising from dripping taps is an indicator of copper ions in the water and hence

39、of uniform corrosion, but it cannot be taken as an indicator of corrosion damage of the copper or copper alloy component itself. Copper ions in water can promote pitting corrosion of less noble metals (e.g. zinc, iron) in the same circuit by depositing as metallic copper, which enhances the local ac

40、tivity of the cathodic oxygen reduction. Protective layers consisting of copper corrosion products normally form on copper and copper alloys. In a few cases the layer is very thin, brown and homogeneous and consists of copper (I) oxide and copper (II) oxide. In most cases, however, there is sufficie

41、nt hydrogen carbonate in the water to allow the formation of a layer of copper hydroxycarbonate Cu 2 (OH) 2 CO 3above the copper (I) oxide and copper (II) oxide. This occurs during the initial operating period, progressively forming a green scale. The actual copper concentration is influenced by the

42、 water composition and the time and conditions of operation such as high flow rates and water hammer. Although copper corrosion products are only sparingly soluble, copper ions are released into water. The formation of copper ions caused by uniform corrosion and dissolution of corrosion products und

43、er stagnant conditions leads to an increase of the concentration of copper ions in the water. The detectable number of copper ions will depend on: EN 12502-2:2004 (E) 8 the concentration of the carbonic acid species and total organic carbon ; the duration of stagnation of water in pipes; the age of

44、the installation; the dilution caused by mixing with fresh water; the method of sampling. The quantity of loosely adherent copper corrosion products that can be removed from the tube walls will depend on: the duration of low water velocity; the extent of any sudden turbulent flow. 4.2.2 Influence of

45、 the characteristics of the metallic material Within a group of alloys with the same major alloying elements the material composition, heat treatment and differences of the surface condition resulting from the manufacturing process, are not known to influence the long-term behaviour of copper and co

46、pper alloys with respect to uniform corrosion. 4.2.3 Influence of the characteristics of the water Under flowing conditions in oxygen-containing waters, the rate of uniform corrosion of copper mainly depends on the pH value of water. Generally, it increases with decreasing pH value of the incoming w

47、ater and is negligible above pH 7,5. In waters of low hydrogen carbonate content, i.e. when c(HCO 3 - ) 1,0 mmol/l, corrosion products other than copper hydroxycarbonate can become those of the lowest solubility, e.g. copper hydroxysulphate Cu 2 (OH) 2 SO 4which forms loosely adherent layers. Loosel

48、y adherent corrosion products are easily dislodged into the water stream. In these cases, the analytically observed copper concentration in the water can exceed the values expected from the dissolution of the corrosion products alone, since copper in particulate form will also be present. In waters

49、with pH values less than 7,5, the detectable number of copper ions generally increases with increasing total organic carbon. The rate of uniform corrosion can be decreased by the addition of inhibitors, e.g. orthophosphates, or by alkalization of the water by addition of NaOH and/or Na 2 CO 3 , by addition of Ca(OH) 2or by use of filters e.g. marble, limestone, dolomite. 4.2.4 Influence of design and construction The formation of prot