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1、BRITISH STANDARD BS EN 12499:2003 Incorporating Corrigendum No. 1 Internal cathodic protection of metallic structures The European Standard EN 12499:2003 has the status of a British Standard ICS 77.060 ? Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled
2、Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/09/2004 01:29:07 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295. -,-,- BS EN 12499:2003 This British Standard was published under the authority of the Standards Policy and Strate
3、gy Committee on 28 February 2003 BSI 1 December 2003 ISBN 0 580 41349 7 National foreword This British Standard is the official English language version of EN 12499:2003. Attention is drawn to the fact that BS 7361-1:1991, Cathodic protection Part 1: Code of practice for land and marine applications
4、, provides general information on cathodic protection. Note that BS 7361-1:1991 will eventually be withdrawn when all the CEN standards relating to cathodic protection currently being prepared are published. The UK participation in its preparation was entrusted to Technical Committee GEL/603, Cathod
5、ic protection, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalo
6、gue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its corr
7、ect application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests inf
8、ormed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 39 and a back cover. The BSI copyright date displayed in this document indicates when the documen
9、t was last issued. Amendments issued since publication Amd. No. DateComments 14828 Corrigendum No. 1 1 December 2003 Changes to National foreword Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959
10、906001, 11/09/2004 01:29:07 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295. -,-,- EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12499 January 2003 ICS 77.060 English version Internal cathodic protection of metallic structures Protection cat
11、hodique interne des structures mtalliquesKathodischer Korrosionsschutz fr die Innenflchen von metallischen Anlagen This European Standard was approved by CEN on 7 November 2002. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this E
12、uropean Standard the status 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 Management Centre or to any CEN member. This European Standard exists in three official versions (Englis
13、h, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic
14、, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Ce
15、ntre: rue de Stassart, 36 B-1050 Brussels 2003 CENAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12499:2003 E Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IH
16、S Licensee=Bureau Veritas/5959906001, 11/09/2004 01:29:07 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295. -,-,- EN 12499:2003 (E) 2 Contents page Foreword3 1Scope 4 2Normative references 4 3Symbols, terms and definitions4 4Principle and criteria f
17、or internal cathodic protection.9 5Factors affecting design and application11 6Design and application of internal cathodic protection.13 7Measurements18 8Commissioning19 9Operation and maintenance20 10Cathodic protection of domestic water heater .21 11Cathodic protection of appliances for heating an
18、d storage of hot water26 12Cathodic protection of structures with variable level feed tanks condensates and similar appliances.28 13Cathodic protection of filtering tanks29 14Internal cathodic protection of wells .31 15Internal cathodic protection of pipes.32 16Cathodic protection of tubular heat ex
19、changers33 Annex A (normative) Test of the electrode potential of galvanic anodes.36 Annex B (informative) Protection potential ranges for low alloy steel compared with Ag/AgCl electrodes in different types of water38 Bibliography39 Copyright British Standards Institution Reproduced by IHS under lic
20、ense with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/09/2004 01:29:07 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295. -,-,- w w w . b z f x w . c o m EN 12499:2003 (E) 3 Foreword This document (EN 12499
21、:2002) has been prepared by Technical Committee CEN/TC 219 “Cathodic protection“, 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 endorsement, at the latest by July 2003, and conflictin
22、g national standards shall be withdrawn at the latest by July 2003. Annex A is normative. Annex B is informative. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech
23、Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy D
24、ocument provided by IHS Licensee=Bureau Veritas/5959906001, 11/09/2004 01:29:07 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295. -,-,- w w w . b z f x w . c o m EN 12499:2003 (E) 4 1 Scope This European Standard specifies the structures, metals and
25、 surfaces which can be protected against corrosion by the application of internal cathodic protection, the electrolytic solutions and the conditions necessary for the application of internal cathodic protection and gives guidance on the application and operation of an effective internal cathodic pro
26、tection system. This standard applies to the internal cathodic protection of domestic water heaters, hot and cold water tanks, circulating water pipes, condensers, heat exchangers and, generally speaking, to every structure containing an electrolytic solution that it is technically possible to catho
27、dically protect. This standard applies to metallic structures which contain stored or circulating water, which can be stagnant or renewed, cold or hot, drinking water or industrial water and also to aqueous suspension. NOTEElectrolytic solutions are assumed to have a conductivity 10-3 Siemens m-1, a
28、nd a pH 4,5. Where the pH 1 g/l6 V; Pt/Nb-c(Cl-) 1 g/l40 V; Pt/Ta-c(Cl-) 1 g/l120 V. Anode to electrolytic solution voltages need, therefore, to be suitably limited. In the presence of other halogenide ions or complexing agents, these reference values may be smaller. If there is no available experie
29、nce for such values, the break-down voltage has to be ascertained experimentally. The life of the platinum film can be affected by the magnitude and frequency of the ripple present in the d.c. supply. Transformer rectifiers with fullwave rectification are preferable to halfwave rectification. 6.6 An
30、ode construction The current distribution requirements for a given geometry of the protected object determine the number and the positioning of the anodes. Common forms of anodes are: wires, wire mesh, rods, profiles, plates, blocks, spheres, spherical segments. 6.7 Current sources The protection cu
31、rrent sources should be equipped with visual control indicators. The protection current sources need to meet the requirements resulting from conditions quoted in 5.5. There are different types of transformer-rectifiers: devices with constant U or I characteristic values at the output; grading or con
32、trolling device; potentiostat (automatic). The whole assembly, which may be wall-mounted is often required to be weatherproof and sometimes certified for use in hazardous atmospheres. The current source shall be protected against damage caused by surges on the input supply caused by lightning. There
33、 shall be a relevant connection between the negative terminal of the rectifier and the protected structure. In case of high currents (amps.) the structure shall be directly connected to the ground and not through the generator terminal to avoid development of an electrochemically significant potenti
34、al difference between the ground and the structure. 6.8 Placing of reference electrodes for potential measurements Depending upon the requirements of the cathodic protection system it may be necessary to install permanent reference electrodes (see 8.2). The location of the permanent measurement poin
35、ts should take into account the following points: areas where the least protection is anticipated; Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/09/2004 01:29:07 MST Questions or co
36、mments about this message: please call the Document Policy Group at 303-397-2295. -,-,- EN 12499:2003 (E) 17 areas where the current distribution is likely to be shielded; areas where the most protection is anticipated (particulary important if overprotection is critical). These measures should enab
37、le a potential distribution curve to be constructed. 6.9 Safety instructions 6.9.1 Danger of electric shock The current normally used for impressed current internal cathodic protection is rectified a.c. taken from a step down transformer and a rectifier. Protection against electric shock shall be se
38、cured for suitable measures against direct and indirect contact according to HD 384.4.41 S2 or equivalent national safety standards (e.g. SELV). 6.9.2 Evolution of dangerous gases 6.9.2.1 General Cathodic protection can build up gaseous hydrogen, gaseous oxygen and chlorine. Some mixtures of oxygen
39、and hydrogen are explosive; chlorine can be toxic and corrosive. The formation of gases can be kept to a minimum by the incorporation of a system of automatic control into the cathodic protection installation and by carefully designing the distribution of the anodes. Where impressed current internal
40、 cathodic protection is used in vessels normally containing hazardous atmospheres, provision shall be made to prevent sparking if the anode is operated outside liquid level. Procedures to be adopted may include positioning of anode so that it is always submerged and/or incorporation of emergency shu
41、t down procedures so that if the anode is temporary exposed all dc current is disabled. 6.9.2.2 Release of hydrogen gas In impressed current systems, and with galvanic anodes (particulary magnesium anodes), excessive polarisation can cause evolution of hydrogen gas on the protected structure. Thus,
42、in situations such as closed tanks where hydrogen can collect, an explosion hazard can arise. To avoid this hazard, it is necessary for all designs to include adequate venting to prevent the build up of a significant gaseous volume of hydrogen. Where hydrogen evolution could produce an explosion haz
43、ard, the structure/electrolytic solution potential should be carefully monitored. 6.9.2.3 Chlorine evolution For an impressed current cathodic protection in electrolytic solutions having a high rate of chloride, specially at low pH, the anodic reaction can result in the electrolytic formation of chl
44、orine. Such a formation can cause either physical discomfort or downstream corrosion effects. In order to reduce chlorine production, the anodic current density can be reduced by a reduction in the cathodic protection demand current and by an increase in the surface area of the anodes. 6.9.3 Emptyin
45、g and opening Before opening an enclosed structure the impressed cathodic protection system shall be turned off. The structure shall be completely filled with electrolytic solution and degassed. Only after that may the structure be emptied with the intake of air and opened. Copyright British Standar
46、ds Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/09/2004 01:29:07 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295. -,-,- EN 12499:2003 (E) 18 6.9.4 Measures
47、for unsteady operation It is necessary to establish whether any special precautions should be taken to cater for intermittent operation, change of use, variations in temperature and levels of concentration, and flow rate. Such provisions should include one of the following: manual or automatic adjus
48、tment of the transformer rectifier output; or automatic switching off. If a protected structure is affected in this way then plant specific instructions shall be detailed in an operating manual. Instructions for re-commissioning the cathodic protection system shall also be detailed in the operating instructions. 7 Measurements 7.1 General Measurements are necessary to ascertain the effectiveness of a cathodic protection system before commissioning. 7.2 Insulation measurements In impre