《ISO-12473-2006.pdf》由会员分享，可在线阅读，更多相关《ISO-12473-2006.pdf（36页珍藏版）》请在三一文库上搜索。
1、 Reference number ISO 12473:2006(E) ISO 2006 INTERNATIONAL STANDARD ISO 12473 First edition 2006-04-01 General principles of cathodic protection in sea water Principes gnraux de la protection cathodique en eau de mer Copyright International Organization for Standardization Provided by IHS under lice
2、nse with ISO Licensee=Qatar Petroleum/5943408001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 12473:2006(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be p
3、rinted or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no
4、 liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file
5、 is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2006 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form o
6、r by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47
7、E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2006 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qatar Petroleum/5943408001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or networking pe
8、rmitted without license from IHS -,-,- ISO 12473:2006(E) ISO 2006 All rights reserved iii Foreword 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 ou
9、t 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 co
10、llaborates closely with the International Electrotechnical 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
11、Standards. 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. Attention is drawn to the possibility that some of the element
12、s of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 12473 was prepared by the European Committee for Standardization (CEN) (as EN 12473) and was adopted, under a special “fast-track procedure”, by Technical Comm
13、ittee ISO/TC 156, Corrosion of metals and alloys, in parallel with its approval by the ISO member bodies. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qatar Petroleum/5943408001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or netw
14、orking permitted without license from IHS -,-,- Page 2 EN 12473:2000 ContentsPage Foreword.iii 1Scope1 2Normative references1 3Terms and definitions.1 4Corrosion principles of buried or immersed metals 5 4.1The nature of metallic corrosion 5 4.2Polarisation. 6 5Principles of cathodic protection . 8
15、6The application of cathodic protection.10 6.1Sacrificial anode method10 6.2Impressed current method.10 6.3Hybrid systems10 7Determination of level of cathodic protection13 7.1Measurement of protection level.13 7.2Reference electrodes13 7.3Potentials of reference electrodes 13 7.4Potential measureme
16、nt.14 8Guidance for protection14 8.1General.14 8.2Steel14 8.3Other metallic materials16 9Design considerations18 9.1Introduction .18 9.2Technical and operating data 19 9.3Surfaces to be protected19 9.4Protective coatings.19 9.5Availability of electrical power.19 9.6Weight limitations .19 9.7Adjacent
17、 structures.19 iv ISO 2006 All rights reserved ISO 12473:2006(E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qatar Petroleum/5943408001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or networking permitted without license from IHS
18、 -,-,- Page 3 EN 12473:2000 9.8Installation considerations.20 9.9Current demand 20 10Effect of environmental factors on current demand .20 10.1Introduction .20 10.2Dissolved oxygen20 10.3Sea currents.20 10.4Calcareous deposits.21 10.5Temperature.21 10.6Salinity22 10.7pH22 10.8Marine fouling22 10.9Ef
19、fect of depth.22 10.10Seasonal variations and storms22 11Secondary effects of cathodic protection 22 11.1Alkalinity 23 11.2Environmentally-assisted cracking.23 11.3Chlorine24 11.4Stray currents and Interference effects24 12The use of cathodic protection in association with surface coatings.24 12.1In
20、troduction .24 12.2Coating selection 25 12.3Coating breakdown.25 Annex A (normative) Reference electrodes26 Bibliography28 ISO 2006 All rights reserved v ISO 12473:2006(E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qatar Petroleum/5943408
21、001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or networking permitted without license from IHS -,-,- Page 4 EN 12473:2000 Foreword This European Standard has been prepared by Technical Committee CEN/TC 219 “Cathodic protection“, the secretariat of which is held by BSI. This European Sta
22、ndard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2000, and conflicting national standards shall be withdrawn at the latest by July 2000. According to the CEN/CENELEC Internal Regulations, the national standard
23、s organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Annex A of thi
24、s European standard is normative. vi ISO 2006 All rights reserved ISO 12473:2006(E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qatar Petroleum/5943408001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or networking permitted witho
25、ut license from IHS -,-,- Page 5 EN 12473:2000 1Scope This European Standard covers the general principles of cathodic protection including the criteria for protection, environmental and design considerations and secondary effects of cathodic protection and is intended as an introduction to other Eu
26、ropean Standards in the general series “Cathodic Protection of Steel Structures in Sea Water“. This European Standard provides a link between the theoretical aspects and the practical applications of cathodic protection as contained in the European Standards: prEN 12474:1997, Cathodic protection for
27、 submarine pipelines. EN 12495:2000, Cathodic protection for fixed steel offshore structures. prEN 12496:1997, Galvanic anodes for cathodic protection in sea water and saline mud. prEN 13173:1998, Cathodic protection for steel offshore floating structures. This group of European Standards does not c
28、over cathodic protection of steel in concrete whether immersed or atmospherically exposed. These aspects are covered by prEN 12696-1:1997 and prEN 12696-2. 2Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative ref
29、erences are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references th
30、e latest edition of the publication referred to applies. EN ISO 8044, Corrosion of metals and alloys Basic terms and definitions (ISO 8044:1999). 3Terms and definitions For the purposes of this European Standard the terms and definitions in EN ISO 8044 and the following apply: 3.1 acidity presence o
31、f an excess of hydrogen ions over hydroxyl ions (pH 7) 3.3 anaerobic condition absence of free oxygen in the electrolyte 3.4 anodic area that part of a metal surface which acts as an anode 3.5 bond metal conductor, usually of copper, connecting two points with the intention of making the points equi
32、potential 3.6 calcareous deposits minerals precipitated on the steel cathode because of the increased alkalinity caused by cathodic protection ISO 12473:2006(E) ISO 2006 All rights reserved1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qata
33、r Petroleum/5943408001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or networking permitted without license from IHS -,-,- Page 6 EN 12473:2000 3.7 calomel reference electrode reference electrode consisting of mercury and mercurous chloride in a saturated solution of potassium chloride 3.8
34、 cathodic area that part of a metal surface which acts as a cathode 3.9 cathodic disbonding failure of adhesion between a coating and a metallic surface that is directly attributable to the application of cathodic protection 3.10 cathodic protection system entire installation, including active and p
35、assive elements, that provides cathodic protection 3.11 cell complete electrolytic system comprising of a cathode and an anode in electrical contact and with an intervening electrolyte 3.12 coating breakdown factor coating breakdown factor is the anticipated reduction in cathodic current density due
36、 to the application of an electrically insulating coating when compared to that of bare steel 3.13 coating defect discontinuity in the protective coating 3.14 coating resistance electrical resistance between a coated metal and the electrolyte. It is determined largely by the size and number of coati
37、ng defects and coating pores and is, therefore, indicative of the condition of the coating 3.15 conductor substance in which electric current flows 3.16 continuity bond bond designed and installed specifically to ensure electrical continuity of a structure 3.17 copper/copper sulphate reference elect
38、rode reference electrode consisting of copper in a saturated solution of copper sulphate 3.18 corrosion interference increase or decrease in the rate of corrosion, or the tendency towards corrosion, of an immersed structure caused by the interception of part of the cathodic protection current applie
39、d to another immersed structure 3.19 depolarization removal of factors resisting the flow of current in a cell 3.20 dielectric shield alkali resistant organic coating applied to the structure being protected in the immediate vicinity of an impressed current anode to enhance the spread of cathodic pr
40、otection and minimize the risk of hydrogen damage to the protected structure in the vicinity of the anode ISO 12473:2006(E) 2 ISO 2006 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qatar Petroleum/5943408001 Not for Resal
41、e, 04/12/2007 01:58:31 MDTNo reproduction or networking permitted without license from IHS -,-,- Page 7 EN 12473:2000 3.21 drainage bond bond to achieve electric drainage 3.22 driving potential difference between the structure/electrolyte potential and the anode/electrolyte potential 3.23 electrical
42、 resistance of coating see coating resistance 3.24 electronegative qualification applied to a metallic electrode to indicate that its potential is negative with respect to another metallic electrode in the system 3.25 electro-osmosis passage of a liquid through a porous medium under the influence of
43、 a potential difference 3.26 environmentally assisted cracking brittle fracture of a normally ductile material in which the corrosive effect of the environment is a contributory factor 3.27 galvanic action spontaneous electrochemical reaction which occurs in a system comprising a cathode and an anod
44、e in electrical contact and with an intervening electrolyte, resulting in corrosion of the anode 3.28 groundbed system of immersed electrodes connected to the positive terminal of an independent source of direct current and used to direct the cathodic protection current onto the structure being prot
45、ected 3.29 holiday see coating defect 3.30 impressed current anode anode in an impressed current installation 3.31 insulated flange flanged joint between adjacent lengths of pipe in which the nuts and bolts are electrically insulated from one or both of the flanges and the gasket is non-conducting,
46、so that there is an electrical discontinuity in the pipeline at that point 3.32 ion atom, or group of atoms, carrying a charge of positive or negative electricity 3.33 isolating joint electrically discontinuous joint or coupling between two lengths of pipe, inserted in order to provide electrical di
47、scontinuity between them ISO 12473:2006(E) ISO 2006 All rights reserved3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Qatar Petroleum/5943408001 Not for Resale, 04/12/2007 01:58:31 MDTNo reproduction or networking permitted without license
48、from IHS -,-,- Page 8 EN 12473:2000 3.34 over polarization when the structure to electrolyte potentials are more negative than those recommended for satisfactory cathodic protection. Over polarization provides no useful function and may even cause damage to the structure by excessive production of gases which may cause embrittlement or protective coating damage 3.35 polarization change in the potential of an electrode as the result of current fl