EN 14505-2005 en Cathodic protection of complex structures《复杂构造的阴极保护》.pdf

1、BRITISH STANDARD BS EN 14505:2005 Cathodic protection of complex structures The European Standard EN 14505:2005 has the status of a British Standard ICS 77.060 BS EN 14505:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 19 May 2005 BSI 1

2、9 May 2005 ISBN 0 580 46033 9 National foreword This British Standard is the official English language version of EN 14505:2005. Reference should also be made to BS 7361, Code of practice for land and marine applications, which will eventually be withdrawn when all the CEN standards relating to cath

3、odic protection currently being prepared, are published. The UK participation in its preparation was entrusted to Technical Committee GEL/603, Cathodic protection, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cros

4、s-references The British 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

5、British Standards 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; pr

6、esent to the responsible 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, a

7、n inside front cover, the EN title page, pages 2 to 24, an inside back cover 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 CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN1

8、4505 April2005 ICS77.060 Englishversion Cathodicprotectionofcomplexstructures Protectioncathodiquedesstructurescomplexes KathodischerKorrosionsschutzkomplexerAnlagen ThisEuropeanStandardwasapprovedbyCENon15March2005. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatethecon

9、ditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheCentralSecretariatortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German)

10、.Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hu

11、ngary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland,Portugal, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 20

12、05CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN14505:2005:EEN 14505:2005 (E) 2 Contents Page Foreword 3 1 Scope .4 2 Normative references .4 3 Terms and definitions.4 4 Criteria for the cathodic protection of complex structures .4 5 Prerequisites

13、 for the application of cathodic protection to a complex structure 5 6 Base data for design.6 7 Design and prerequisites .7 8 Installation of cathodic protection systems10 9 Commissioning .11 10 Inspection and maintenance12 Annex A (informative) Principle scheme of a complex structure .14 Annex B (i

14、nformative) Example of an industrial complex structure.15 Annex C (informative) Reinforced concrete data in complex structures .16 Annex D (informative) Increasing soil potential .17 Annex E (informative) Groundbed data 21 Bibliography.24 EN 14505:2005 (E) 3 Foreword This European Standard (EN 14505

15、:2005) 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 October 2005, and conflic

16、ting national standards shall be withdrawn at the latest by October 2005. It may be difficult to obtain complete cathodic protection of certain structures when following the general guidelines in EN 12954. This may be due to an electrical connection to one or more metal structures (electrodes) situa

17、ted in the same electrolyte as the structure, which is to be protected. In particular, the structure may be earthed in order to mitigate electrical hazards or the connection to the other structures may be dictated by construction or operational requirements. An electrical connection to a foreign str

18、ucture can result in a significantly increased cathodic protection current demand, since the current flows not only to the structure to be protected but also to the foreign structure. This unwanted increased current demand is enhanced when the foreign structure consists of a metal, which is more nob

19、le (having a more positive resting potential) than the metal in the structure to be protected. Connection to a copper earthing electrode or to the steel reinforcement in a concrete structure are examples of the latter. These difficulties can mean that a significantly increased cathodic protection cu

20、rrent is required because of structures electrically connected to the structure to be protected, resulting in inadequate cathodic protection, current distribution and shielding effects. For this reason, the term “complex structure” has been used. It does not refer to the complexity of the structure

21、or to the complexity of the cathodic protection system. In such conditions the prerequisites, the criteria and the methods described in the present document expand those given in EN 12954. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countr

22、ies are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerla

23、nd and United Kingdom. EN 14505:2005 (E) 4 1 Scope This European Standard applies to the cathodic protection of complex structures. It is applicable to structures, which are to be cathodically protected, but cannot be electrically isolated, whether for technical or safety reasons, from foreign metal

24、lic structures situated in the same electrolyte as the structure to be protected. Such a structure is referred to as a “complex structure”. This European Standard is not applicable to structures that can be protected in accordance with EN 12954. When contacts with foreign structures or defective iso

25、lation from foreign structures exist, but can be corrected, EN 12954 is applicable instead of this document. As an example pipeline network distribution systems are not considered to be complex structures It is assumed in this document that the design, installation, commissioning, inspection and mai

26、ntenance are entrusted to adequately trained, experienced, competent and reliable personnel in order to achieve effective and efficient cathodic protection. Annexes A and B show the principle scheme of a complex structure with examples. 2 Normative references The following referenced documents are i

27、ndispensable 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 12954:2001, Cathodic protection of buried or immersed metallic structures General prin

28、ciples and application for pipelines. EN 50162, Protection against corrosion by stray current from direct current systems. 3 Terms and definitions For the purposes of this European Standard, the terms and definitions given in EN 12954:2001 and the following apply. NOTE For other definitions related

29、to corrosion, refer to EN ISO 8044:1999. 3.1 complex structure structure composed of the structure to be protected and of one or more foreign electrodes, which, for safety or technical reasons, cannot be electrically separated from it 3.2 foreign electrode electrode (anode or cathode), in contact wi

30、th the structure under consideration NOTE a foreign anode is a foreign electrode, which has a more negative potential than the structure, a foreign cathode is a foreign electrode, which has a more positive potential than the structure. 4 Criteria for the cathodic protection of complex structures For

31、 complex structures, the cathodic protection criteria defined in EN 12954 should be used where possible. Indeed, the characteristics of complex structures and the special influential factors (see Clause 5) which can occur means that it is not always possible on every part of the complex structure to

32、 determine by measurement whether these criteria of cathodic protection are met. In this case alternative methods of verification may be selected to EN 14505:2005 (E) 5 ensure an adequate reduction of the corrosion rate. Particular attention should be paid to the selection of these alternative metho

33、ds, and these will depend upon the structure and the soil characteristics. The following three alternative methods may be used as criteria. They are based upon practical experience and are widely used. All structure to electrolyte potential measurements are stated with respect to a copper/saturated

34、copper sulphate reference electrode. a) Potential measurement method An on potential E on equal to or more negative than 1,2 V, if the measuring point is outside the area of influence of the large foreign cathode (e.g. reinforced concrete or copper earthing system) and if the soil resistivity is suf

35、ficiently low (less than about 100 m) with the exception that an on potential E on more negative than 0,8 Vcould be acceptable at entries to, and in the vicinity (within 0,5 m) of large foreign cathodes (demonstrating that the effect of a galvanic cell with the large foreign cathode is mitigated). b

36、) Current method The purpose of this method is to demonstrate that current is able to enter the structure at critical locations either: 1) directly (i.e. when the protection current is switched on, a negative shift from the free corrosion potential E nby at least 0,3 V indicating that probably suffi

37、cient current is entering the structure); or 2) by means of either current density or potential shift measurements at test probes or coupons. NOTE A critical location is location where the probability to have an anodic current leaving the structure to be protected is high (e.g., vicinity of foreign

38、cathode due to galvanic couple, heterogeneity of the soil or shielding effect). c) Depolarisation measurement method A positive shift (depolarisation) on test probes or coupons of at least 0,1 V measured from immediately after disconnection (E off ) to 1 h after disconnection from the structure indi

39、cates that the structure is polarized. These test probes/coupons are disconnected only for measurements. One of these alternative criteria shall be used as a minimum. More than one of these alternative criteria may be required to verify adequate protection over the entire complex structure. Other cr

40、iteria can be used if they can be shown to reduce the external corrosion rate to an acceptable level. 5 Prerequisites for the application of cathodic protection to a complex structure 5.1 General The cathodic protection system depends on the size and shape of the complex structure, the type of coati

41、ng, the aggressive action of the soil and its resistivity, d.c. and a.c interference, national regulations, and also on the technical and economic criteria. To achieve cathodic protection, the conditions given in 5.2 to 5.4 should be satisfied. 5.2 Electrical continuity In the case of a complex stru

42、cture, all metallic parts of the structure to be protected should be electrically continuous. Foreign electrodes should also be electrically continuous. 5.3 Electrical isolation For the cathodic protection system to be properly designed, the form and extent of the structure should be clearly defined

43、 in terms of its location and electrical isolation from foreign structures. EN 14505:2005 (E) 6 If the electrical isolation is ineffective and cannot be restored to its original condition, then the extent of the complex structure should be revised to take this into account. 5.4 External coating Prot

44、ective coatings are not always applied to components in a complex structure (e.g. earthing systems). Uncoated components significantly increase protection current demands and thus add to the difficulties of the application of cathodic protection and increase the risk of interference. Wherever possib

45、le, buried metallic components should be suitably coated. 6 Base data for design 6.1 General In addition to following the principles laid out in EN 12954, other specific data, as given in 6.2 to 6.8, should be used when dealing with complex structures. 6.2 Structure details The surface area of all b

46、uried or immersed components of a complex structure should be ascertained as well as the status of the coating (if any). 6.3 Coatings Types of the different coating applied on all components of a complex structure should be taken into account. 6.4 Environment Depending on the composition of some par

47、ts of a complex structure, particular environmental conditions should be considered, for example, the chloride content of the electrolyte when an integral part of a complex structure is made of stainless steel, or reinforcement steel in concrete (rebar). 6.5 Shielding All relevant information should

48、 be obtained on any feature that might act as a shield to the cathodic protection current or its distribution, e.g. reinforced concrete foundations, pits, ducts, any geotextiles, and pipe sleeves. The location of the anodes with respect to the shields should be selected such that shielding is minimi

49、zed. A shield can be either conductive or non-conductive. A conductive shield can be either a part of the complex structure itself or a foreign structure such as steel sleeves for pipes, large conducting structures (sheet piling and reinforced concrete foundations) close to the structure to be protected. Non-