SIST EN 16222:2014
(Main)Cathodic protection of ships
Cathodic protection of ships
This European Standard defines the general criteria and recommendations for cathodic protection of immersed external ship hulls and appurtenances. This European Standard does not cover safety and environmental protection aspects associated with cathodic protection. Relevant national or international regulations and classification society requirements apply.
Kathodischer Korrosionsschutz von Schiffen
1.1 Allgemeines
Die vorliegende Europäische Norm legt die allgemeinen Kriterien und Empfehlungen für kathodischen Korrosionsschutz von unter Wasser befindlichen Schiffsrümpfen und Zubehör fest.
1.2 Konstruktionen
Diese Europäische Norm gilt für den kathodischen Korrosionsschutz von unter Wasser befindlichen Rümpfen von Schiffen, Booten und anderen Schwimmkörpern mit Selbstantrieb, die üblicherweise zusammen mit ihrem Zubehör wie beispielsweise Ruder, Propeller, Wellen und Stabilisatoren in Meerwasser eingesetzt werden.
Sie gilt auch für den kathodischen Korrosionsschutz von Strahlruder, Seekisten und Wassereinlässen (bis zum ersten Ventil).
Sie gilt nicht für den Schutz von innenliegenden Oberflächen wie beispielsweise Ballasttanks. Dies wird in EN XXXXX behandelt.
Sie gilt nicht für schwimmende Offshore-Anlagen aus Stahl. Diese werden in EN 13173 behandelt.
1.3 Werkstoffe
Diese Europäische Norm gilt für den kathodischen Korrosionsschutz von Schiffsrümpfen vorwiegend aus Manganstählen einschließlich Zubehör aus anderen Eisen- oder Nichteisenlegierungen wie beispielsweise nichtrostender Stahl und Kupferlegierungen usw.
Diese Norm gilt für sowohl beschichtete wie auch unbeschichtete Rümpfe; die meisten Rümpfe sind beschichtet.
Beim kathodischen Schutzsystem muss gewährleitstet sein, dass jede galvanische Verbindung vollständig unter Kontrolle ist.
Diese Europäische Norm gilt nicht für den kathodischen Korrosionsschutz von Rümpfen, die überwiegend aus anderen Werkstoffen bestehen wie beispielsweise Aluminiumlegierungen, nichtrostende Stähle oder Beton.
1.4 Umgebung
Diese Europäische Norm gilt für den Rumpf und Zubehör in Meerwasser und allen Wässern weltweit, in denen das Schiff während seiner Lebensdauer eingesetzt werden könnte.
1.5 Sicherheit und Umweltschutz
Protection cathodique des coques de bateaux
1.1 Généralités
La présente Norme européenne définit les critères généraux et les recommandations concernant la protection
cathodique de la surface externe des coques de bateaux et des parties annexes immergées.
1.2 Structures
La présente Norme européenne couvre la protection cathodique des coques immergées de navires, bateaux
et autres ouvrages flottants autopropulsés, généralement utilisés en eau de mer, ainsi que des parties
annexes telles que les gouvernails, hélices, arbres et stabilisateurs.
Elle traite également de la protection cathodique des propulseurs, manchons de coque et prises d’eau
(jusqu’à la première vanne).
Elle ne couvre pas la protection des surfaces internes telles que les citernes de ballast, qui est traitée dans
l’EN XXXXX.
Elle ne couvre pas les structures en acier flottant en mer, qui sont traitées dans l’EN 13173.
1.3 Matériaux
La présente Norme européenne couvre la protection cathodique des coques de bateaux réalisées
principalement à partir d’acier au carbone/manganèse, y compris des parties annexes réalisées à partir
d’autres alliages ferreux ou non ferreux, tels que les aciers inoxydables et les alliages de cuivre, etc.
La présente norme s’applique à la fois aux coques nues ou revêtues, la plupart des coques étant revêtues.
La protection cathodique doit être conçue de manière à assurer une parfaite maîtrise de tout couplage
galvanique.
La présente Norme européenne ne couvre pas la protection cathodique des coques réalisées principalement
à partir d’autres matériaux comme les alliages d’aluminium, les aciers inoxydables ou le béton.
1.4 Environnement
La présente Norme européenne s’applique à la coque et aux parties annexes utilisées en eau de mer et dans
toutes les eaux mondiales que peut traverser un bateau pendant son service.
Katodna zaščita ladij
Ta evropski standard določa splošna merila in priporočila za katodno zaščito potopljenih ladijskih trupov in pripadajočih elementov. Ta evropski standard ne zajema varnostnih vidikov in vidikov zaščite okolja, povezanih s katodno zaščito. Veljajo ustrezni nacionalni ali mednarodni predpisi in zahteve klasifikacijskih zavodov.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kathodischer Korrosionsschutz von SchiffenProtection cathodique des coques de bateauxCathodic protection of ships47.020.01Splošni standardi v zvezi z ladjedelništvom in konstrukcijami na morjuGeneral standards related to shipbuilding and marine structures25.220.40Kovinske prevlekeMetallic coatingsICS:Ta slovenski standard je istoveten z:EN 16222:2012SIST EN 16222:2014en,fr,de01-julij-2014SIST EN 16222:2014SLOVENSKI
STANDARD
SIST EN 16222:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16222
October 2012 ICS 47.020.01; 77.060 English Version
Cathodic protection of ship hulls
Protection cathodique des coques de bateaux
Kathodischer Korrosionsschutz von Schiffen This European Standard was approved by CEN on 25 August 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 concerning 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 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue 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 16222:2012: ESIST EN 16222:2014
EN 16222:2012 (E) 2 Contents Page Foreword .4Introduction .51Scope .61.1General .61.2Structures .61.3Materials .61.4Environment .62Normative references .63Terms and definitions .74Competence of personnel .75Design basis .85.1General .85.2Cathodic protection criteria .85.3Design process .95.4Design parameters. 105.5Current demand . 105.6Cathodic protection systems . 135.7Electrical continuity . 145.8Fitting out period . 146Impressed current system . 146.1Objectives . 146.2Design considerations . 146.3Equipment considerations . 157Galvanic anodes system . 197.1Objectives . 197.2Design considerations . 197.3Anode materials . 197.4Factors determining the anode current output and operating life . 207.5Location of anodes . 208Commissioning, Operation and Maintenance . 218.1Objectives . 218.2Measurement Procedures . 218.3Commissioning: Galvanic Systems . 218.4Commissioning: Impressed Current Systems . 228.5Operation and maintenance . 238.6Dry-docking period . 249The protection of ships' hulls during fitting out and when laid up . 259.1Fitting out period . 259.2Lay up period . 2510Documentation . 2510.1Objectives . 2510.2Impressed current system . 2610.3Galvanic anode systems . 26Annex A (informative)
Impressed current system for hulls of ships based on two cathodic protection zones . 28SIST EN 16222:2014
EN 16222:2012 (E) 3 Annex B (informative)
Guidance on design current values for cathodic protection of hulls of ships . 29B.1Typical design current densities for the cathodic protection of bare steel (Jb) . 29B.2Coating breakdown of conventional paint systems (fc) . 29B.3Typical current densities for global approach of the cathodic protection of coated ships (Jg) . 30Annex C (informative)
Anode resistance, current and life duration formulae . 31C.1Anode resistance formulae . 31C.2Calculation of the anode resistance at the end of life . 32C.3Electrolyte resistivity . 33C.4Galvanic anode current output . 35C.5Anode life . 35C.6Minimum Net Weight Requirement . 35Annex D (informative)
Electrical bonding systems . 37Annex E (informative)
Monitoring of electrical bonding of a ship's propeller . 39Annex F (informative)
Impressed current system for ships based on an aft (stern) system only . 40Annex G (informative)
Location of galvanic anodes in the stern area . 41Annex H (informative)
Electrochemical characteristics of impressed current anodes . 42Annex I (informative)
Cofferdam arrangements . 43Annex J (informative)
Cathodic protection of a moored ship using suspended galvanic anodes . 45Bibliography . 46 SIST EN 16222:2014
EN 16222:2012 (E) 4 Foreword This document (EN 16222:2012) 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 April 2013, and conflicting national standards shall be withdrawn at the latest by April 2013. 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 identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, 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. SIST EN 16222:2014
EN 16222:2012 (E) 5 Introduction Cathodic protection is usually applied, mostly as a complement to protective coatings, to protect the external surfaces of ship hulls and immersed appurtenances from corrosion due to seawater. Cathodic protection works by supplying sufficient direct current to the immersed external surface of the structure in order to change the steel to electrolyte potential to values where corrosion is insignificant. The general principles of cathodic protection are detailed in EN 12473. SIST EN 16222:2014
EN 16222:2012 (E) 6 1 Scope 1.1 General This European Standard defines the general criteria and recommendations for cathodic protection of immersed external ship hulls and appurtenances.
This European Standard does not cover safety and environmental protection aspects associated with cathodic protection. Relevant national or international regulations and classification society requirements apply. 1.2 Structures This European Standard covers the cathodic protection of the underwater hulls of ships, boats and other self propelled floating vessels generally used in seawater together with their appurtenances such as rudders, propellers, shafts and stabilisers. It also covers the cathodic protection of thrusters, sea chests and water intakes (up to the first valve). It does not cover the protection of internal surfaces such as ballast tanks.
It does not cover steel offshore floating structures which are covered in EN 13173. 1.3 Materials This European Standard covers the cathodic protection of ship hulls fabricated principally from carbon manganese steels including appurtenances of other ferrous or non-ferrous alloys such as stainless steels and copper alloys, etc.
This European Standard applies to both coated and bare hulls; most hulls are coated. The cathodic protection system should be designed to ensure that there is a complete control over any galvanic coupling. This European Standard does not cover the cathodic protection of hulls principally made of other materials such as aluminium alloys, stainless steels or concrete. 1.4 Environment This European Standard is applicable to the hull and appurtenances in seawater and all waters which could be found during a ship’s world-wide deployment. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12473, General principles of cathodic protection in sea water EN 12496, Galvanic anodes for cathodic protection in seawater and saline mud
EN 13509, Cathodic protection measurement techniques EN 50162, Protection against corrosion by stray current from direct current systems SIST EN 16222:2014
EN 16222:2012 (E) 7 EN ISO 8044, Corrosion of metals and alloys
Basic terms and definitions (ISO 8044) 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN ISO 8044, EN 12473 and the following apply. 3.1 immersed zone zone located below the water line at draught corresponding to normal working conditions 3.2 underwater hull part of the hull vital for its stability and buoyancy of a ship Note 1 to entry: Part of the underwater hull might include that below the light water line. 3.3 boot topping section of the hull between light and fully loaded conditions which may be intermittently immersed 3.4 cathodic protection zone
part of the structure which can be considered independently with respect to cathodic protection design Note 1 to entry: A single zone may comprise a variety of components with differing design parameters. 3.5 submerged zone zone including the immersed zone and the boot topping 3.6 driving voltage difference between the structure/electrolyte potential and the anode/electrolyte potential when the cathodic protection is operating 3.7 closed circuit potential potential measured at a galvanic anode when a current is flowing in between the anode and the surface being protected 4 Competence of personnel Personnel who undertake the design, supervision of installation, commissioning, supervision of operation, measurements, monitoring and supervision of maintenance of cathodic protection systems shall have the appropriate level of competence for the tasks undertaken. This competence should be independently assessed and documented. EN 15257 constitutes a suitable method of assessing and certifying competence of cathodic protection personnel which may be utilised.
Competence of cathodic protection personnel to the appropriate level for tasks undertaken should be demonstrated by certification in accordance with EN 15257 or by another equivalent prequalification procedure. SIST EN 16222:2014
EN 16222:2012 (E) 8 5 Design basis 5.1 General The objective of a cathodic protection system is to deliver sufficient current to protect each part of the structure and appurtenances and distribute this current so that the structure to electrolyte potential of each part of the structure is within the limits given by the protection criteria (see 5.2). Potentials should be as uniform as possible over the whole submerged surfaces. This objective may only be approached by adequate distribution of the protective current over the structure during its normal service conditions. This may be difficult to achieve in some areas such as water intakes, thrusters, sea chests, where specific provisions should be considered. The cathodic protection system for a ship is generally combined with a protective coating system, even though some appurtenances such as propellers are generally not coated. Electrochemical anti-fouling systems are often used within sea chests to prevent fouling of seawater intake systems. The possibility of interaction between the anti-fouling system and the cathodic protection system should be considered in the design and installation of the anti-fouling system. Cathodic protection within sea chests may adversely affect, by stray current interaction, box coolers in sea chests (typically copper nickel alloy tubes) if the box coolers are electrically isolated from the sea chest. The possibility of interaction should be taken into account in designing the cathodic protection requirements for the sea chest. The cathodic protection system should be designed either for the life of the ship or on the basis of the dry-docking intervals. The above objectives shall be achieved by the design of a cathodic protection system using galvanic anodes, an impressed current system or a combination of both. The design, the installation, the energising, the commissioning, the long-term operation and the documentation of all of the elements of cathodic protection systems shall be fully recorded.
EN ISO 9001 constitutes a suitable Quality Management Systems Standard which may be utilised.
Each element of the work shall be undertaken in accordance with a fully documented quality plan.
Each stage of the design shall be checked and the checking shall be documented. Each stage of the installation, energising, commissioning and operation shall be the subject of appropriate visual, mechanical and/or electrical testing and all testing shall be documented. All test instrumentation shall have valid calibration certificates traceable to national or European Standards of calibration. The documentation shall constitute part of the permanent records for the works. 5.2 Cathodic protection criteria The criteria for cathodic protection are detailed in EN 12473. To achieve an adequate cathodic protection level, steel structures should have potentials as follows. The accepted criterion for protection of steel in aerated seawater is a protection potential more negative than – 0,80 V measured with respect to Ag/AgCl/seawater reference electrode. This corresponds approximately to + 0,23 V when measured with respect to pure zinc electrode (e.g. alloy type Z2 as defined in EN 12496) or SIST EN 16222:2014
EN 16222:2012 (E) 9 + 0,25 V when measured with respect to zinc electrode made with galvanic anode alloy types Z1, Z3 or Z4 as defined in EN 12496. A negative limit of – 1,10 V with respect to Ag/AgCl/seawater reference electrode is generally recommended in order to avoid coating disbondment and / or increase in fatigue propagation rates.
Where there is a possibility of hydrogen embrittlement of steels or other metals which may be adversely affected by cathodic protection to excessively negative values, an additional less negative potential limit shall be adopted. If insufficient documentation is available for a given material, this specific negative potential limit relative to the metallurgical and mechanical conditions shall be determined by mechanical testing at the limit polarised potential. For conventional steels, this limit is – 1,10 V (Ag/AgCl/seawater reference electrode). Refer to EN 12473 for more details. The above potential criteria and limit values are “polarised” and are expressed without IR errors. IR errors, due to cathodic protection current flowing though resistive electrolyte and surface films on the protected surface, are generally considered insignificant in marine applications. Potential measurements using “Instant OFF” techniques or “coupon Instant OFF” techniques may be necessary in applications described in this European Standard in order to adequately demonstrate the achievement of the above protection criteria (see EN 13509). Particular attention should be given to this in brackish waters and close to impressed current anodes. 5.3 Design process The design of a cathodic protection system shall be conducted according to the following different stages: a) the structure is divided into various cathodic protection zones which will be considered independently with respect to cathodic protection design (see 5.4.2); b) each component included in a cathodic protection zone is fully described (see 5.4.3); c) the service conditions are well established (see 5.4.4); d) the current demand is determined for each cathodic protection zone from (see 5.5): 1) areas of components; 2) current densities regarding the state of components and service conditions; Two different approaches may be considered concerning the choice of current densities: 3) From current densities of bare metal (see 5.5.2) introducing a breakdown factor for the coating (see 5.5.3) taking into consideration physicochemical ageing and mechanical damage versus time; 4) From a global approach (see 5.5.3) based on experience. When the first approach is selected, two types of current demands are determined (see 5.5.4): 5) maximum current demand (Imax); 6) mean current demand (Imean), e) the cathodic protection system is determined for each cathodic protection zone (see 5.6); f) an electrical continuity is planned between all components of a cathodic protection zone (see 5.7); g) the appropriate cathodic protection system dedicated to a cathodic protection zone is designed (see Clauses 6 and 7). SIST EN 16222:2014
EN 16222:2012 (E) 10 NOTE The design of impressed current systems is based on maximum current demand. The design of galvanic anodes systems is based on maximum current demand and mean current demand. 5.4 Design parameters 5.4.1 General The design of a cathodic protection system takes into consideration the following parameters: structure subdivision, components characteristics and service conditions. 5.4.2 Structure subdivision The submerged surfaces of a ship hull can be divided into different cathodic protection zones which are then considered independently with respect to cathodic protection design although they are not electrically isolated. For instance, the underwater hull can be divided into two main cathodic protection zones: the forward (or bow) zone and the aft (or stern) zone illustrated by the drawing in Annex A. This subdivision is related to the higher current demand of the aft zone due to high water flow rates, turbulence and the presence of dissimilar metals due to the propeller(s). The aft cathodic protection zone includes the following appurtenances: the aft part of the hull, propeller(s), shaft(s), rudder(s), etc. Some specific components may constitute a cathodic protection zone by themselves (e.g. openings of sea chests, thrusters, rudders etc). 5.4.3 Components characteristics Each component of a cathodic protection zone as mentioned above shall be fully detailed in the design including: material, specific potential limit (where applicable) area and coating characteristics (type, lifetime and coating breakdown factor). 5.4.4 Service conditions The design of cathodic protection system(s) shall be related to the service conditions which include: lifetime, environment and operating conditions. a) Lifetime Either the whole design life or dry-docking intervals should be considered. b) Environment The characteristics of seawater should be established. Refer to EN 12473 General principles of cathodic protection in seawater. Particular attention is required for vessels anticipated to operate in ice conditions or estuarine/freshwater conditions.
c) Operating conditions The average and the maximum speeds should be considered combined with the percentages of lifetime associated to static (berthed) and dynamic (sailing) conditions. 5.5 Current demand 5.5.1 General To achieve protection criteria for the conditions outlined in 5.2 it is necessary to select the appropriate design current density for each component with respect to the environmental and service conditions. SIST EN 16222:2014
EN 16222:2012 (E) 11 The current demand of each metallic component of the structure is the result of the product of its surface area multiplied by the protection current density for the bare steel and by the coating breakdown factor. See Annexes B and C for design current density and anode resistance calculation guidance. 5.5.2 Design current density for bare steel The selection of design current densities may be based either on experience gained from similar ships operating in a similar manner or from specific tests and measurements. The protection current density of bare steels and other bare metals depends on the kinetics of electrochemical reactions. It varies with parameters such as the material, potential, surface condition, dissolved oxygen content in seawater, flow rate or speed, temperature. For each particular environmental and service conditions mentioned in 5.4.4 c), protection current density shall be evaluated. Typical values of design current densities as used for bare steel are given in Annex B. 5.5.3 Design current density for coated steel The cathodic protection system is generally combined with suitable coating systems. The coating reduces the protection current density and improves the current distribution over the surface. The reduction of protection current density from bare steel to coated steel may be in a ratio of 100 to 1 or even more. However the protection current density of coated steel will increase with time as the coating deteriorates. An initial coating breakdown factor related mainly to mechanical damage occurring during the fabrication of the ships should be considered. A coating deterioration rate (i.e. an increase of the coating breakdown factor with time) should be selected in order to take into account the coating ageing and mechanical damage occurring to the coating during the design life of the ship’s cathodic protection system or a period corresponding to the dry-docking interval. The values are strongly dependent on the actual construction and operational conditions. Guidelines for the values of coating breakdown factors are given in Annex B. The design current density required for the protection of coated steel is equal to the product of the current density for bare steel (see 5.5.2) and the coating breakdown factor: cbcf.JJ= where Jc is the protection current density for coated metal in A/m2; Jb is the protection current density for bare metal in A/m2; fc is the coating breakdown factor which varies with time due to ageing and mechanical damage: fc = 0 for a perfectly insulating coating fc = 1 for a coating with no insulation properties (equivalent to bare metal). This formula should be applied for each individual component or cathodic protection zone as defined in 5.3 where the coating or current density for bare metal can be different. SIST EN 16222:2014
EN 16222:2012 (E) 12 A global approach for the estimation of the protection current density for coated structures may be considered when values for design parameters are well known from numerous past experiences. Where a global approach is considered an average value of this protection current density (Jg) is taken into consideration. Guidelines for values of current densities for a global approach are given in Annex B. If a “global approach” is taken for the design it shall be documented in detail regarding the class of vessel and service for which the global track record has been collected and the basis upon which the satisfactory cathodic protection performance has been evaluated. 5.5.4 Current demand Unless a global approach is adopted f
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