BS EN 12473:2014
$167.15
General principles of cathodic protection in seawater
| Published By | Publication Date | Number of Pages |
| BSI | 2014 | 44 |
This European Standard covers the general principles of cathodic protection when applied in seawater, brackish waters and marine mud. It is intended to be an introduction, to provide a link between the theoretical aspects and the practical applications, and to constitute a support to the other European Standards devoted to cathodic protection of steel structures in seawater.
This European Standard specifies the criteria required for cathodic protection. It provides recommendations and information on reference electrodes, design considerations and prevention of the secondary effects of cathodic protection.
The practical applications of cathodic protection in seawater are covered by the following standards:
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EN 12495, Cathodic protection for fixed steel offshore structures;
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EN ISO 13174, Cathodic protection of harbour installations (ISO 13174);
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EN 12496, Galvanic anodes for cathodic protection in seawater and saline mud;
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EN 13173, Cathodic protection for steel offshore floating structures;
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EN 16222, Cathodic protection of ship hulls;
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EN 12474, Cathodic protection of submarine pipelines;
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ISO 15589-2, Petroleum, petrochemical and natural gas industries — Cathodic protection of pipeline transportation systems — Part 2: Offshore pipelines.
For cathodic protection of steel reinforced concrete whether exposed to seawater or to the atmosphere, EN ISO 12696 applies.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 6 | Foreword |
| 7 | 1 Scope 2 Normative references 3 Terms, definitions, abbreviations and symbols |
| 11 | 4 Application of cathodic protection in seawater 4.1 General 4.2 Galvanic anode method |
| 12 | 4.3 Impressed current method 4.4 Hybrid systems Figure 1 — Representation of cathodic protection using a galvanic anode on a structure in the seawater |
| 13 | Figure 2 — Representation of impressed current cathodic protection using inert anode in seawater Table 1 — Comparison of galvanic and impressed current systems |
| 14 | 5 Determination of level of cathodic protection 5.1 Measurement of protection level 5.2 Reference electrodes 5.3 Potentials of reference electrodes 5.4 Verification of reference electrodes 5.5 Potential measurement |
| 15 | 6 Cathodic protection potential criteria 6.1 General 6.2 Carbon-manganese and low alloy steels |
| 16 | Table 2 —Potential criteria for the cathodic protection of various metals and alloys in seawater |
| 17 | Figure 3 — Corrosion, cathodic protection and over-polarization regimes of steel expressed as a function of electrode potential 6.3 Other metallic materials 6.3.1 General 6.3.2 Stainless steels 6.3.2.1 Role of microstructure 6.3.2.2 Austenitic stainless steels |
| 18 | 6.3.2.3 Duplex stainless steels 6.3.2.4 Martensitic stainless steels 6.3.3 Nickel alloys 6.3.4 Aluminium alloys |
| 19 | 6.3.5 Copper alloys 7 Design considerations 7.1 Introduction 7.2 Technical and operating data 7.2.1 Design life 7.2.2 Materials of construction |
| 20 | 7.3 Surfaces to be protected 7.4 Protective coatings 7.5 Availability of electrical power 7.6 Weight limitations 7.7 Adjacent structures 7.8 Installation considerations |
| 21 | 7.9 Current demand 8 Effect of environmental factors on current demand 8.1 Introduction 8.2 Dissolved oxygen 8.3 Sea currents 8.4 Calcareous deposits |
| 22 | 8.5 Temperature 8.6 Salinity |
| 23 | 8.7 pH 8.8 Marine fouling 8.9 Effect of depth 8.10 Seasonal variations and storms 9 Secondary effects of cathodic protection 9.1 General |
| 24 | 9.2 Alkalinity 9.3 Environmentally-assisted cracking 9.3.1 General 9.3.2 Hydrogen embrittlement 9.3.3 Corrosion fatigue |
| 25 | Figure 4 — Typical S-N curve for fatigue behaviour of steel in various environments 9.4 Chlorine 9.5 Stray currents and interference effects |
| 26 | 10 Use of cathodic protection in association with coatings 10.1 Introduction 10.2 Coating selection |
| 27 | 10.3 Coating breakdown |
| 28 | Annex A (informative) Corrosion of carbon-manganese and low-alloy steels A.1 Nature of metallic corrosion |
| 29 | A.2 Polarization |
| 30 | Figure A.1 — Polarization diagram schematically representing the electrochemistry of aqueous corrosion |
| 31 | Figure A.2 — Polarization diagram representing control of corrosion rate by sluggish cathodic kinetics (in this case it is controlled by the rate of arrival of oxygen at the surface) and the effect of increasing oxygen availability |
| 32 | Annex B (informative) Principles of cathodic protection |
| 33 | Figure B.1 — Schematic diagram showing how corrosion can be reduced or stopped by applying cathodic protection |
| 35 | Annex C (informative) Reference electrodes C.1 General C.2 Silver/silver chloride/seawater electrode |
| 36 | Figure C.1 — Nomogram for the correction of potential readings made with the Ag/AgCl/seawater electrode in waters of varying resistivity against the saturated calomel electrode (S.C.E) and Cu/CuSO4 reference electrodes 13 |
| 37 | C.3 The zinc/seawater electrode C.4 Verification of reference electrodes |
| 38 | Table C.1 — Potentials of reference electrodes with respect to the normal hydrogen electrode (at 25 C) |
| 39 | Annex D (informative) Corrosion of metallic materials other than carbon-manganese and low-alloy steels typically subject to cathodic protection in seawater D.1 Stainless steels D.2 Nickel alloys D.3 Aluminium alloys |
| 40 | D.4 Copper alloys |
| 41 | Bibliography |
