AS 2832.4-1994

1 - AS 2832.4-1994 CATHODIC PROTECTION OF METALS - INTERNAL SURFACES
4 - PREFACE
5 - CONTENTS
7 - FOREWORD
8 - SECTION 1 SCOPE AND GENERAL
8 - 1.1 SCOPE
8 - 1.2 REFERENCED DOCUMENTS
9 - 1.3 DEFINITIONS
9 - 1.3.1 Anaerobic
9 - 1.3.2 Anode
9 - 1.3.3 Anode screen
9 - 1.3.4 Anode shield
9 - 1.3.5 Back e.m.f.
9 - 1.3.6 Bond (electrical)
9 - 1.3.7 Bond (coating)
9 - 1.3.8 Cathode
9 - 1.3.9 Cathodic disbonding
9 - 1.3.10 Cathodic protection
9 - 1.3.11 Copper/copper sulfate reference electrode
9 - 1.3.12 Corrosion
9 - 1.3.13 Corrosion cell anode
9 - 1.3.14 Corrosion current
9 - 1.3.15 Current density (at anode)
9 - 1.3.16 Current density (at cathode)
9 - 1.3.17 Current density (at coated cathode)
9 - 1.3.18 Earth (noun)
9 - 1.3.19 Earth (verb)
9 - 1.3.20 Electrode
9 - 1.3.21 Electrode potential
10 - 1.3.22 Electrolyte
10 - 1.3.23 Foreign (secondary) structure
10 - 1.3.24 Galvanic action
10 - 1.3.25 Galvanic anode
10 - 1.3.26 Half-cell
10 - 1.3.27 Impressed current
10 - 1.3.28 Impressed current anode
10 - 1.3.29 Insulating joint
10 - 1.3.30 Interference
10 - 1.3.31 Interrupter
10 - 1.3.32 Loop resistance
10 - 1.3.33 Polarization
10 - 1.3.34 Polarization cell
10 - 1.3.35 Primary structure
10 - 1.3.36 Protective potential
10 - 1.3.37 Protective current
10 - 1.3.38 Reference electrode
10 - 1.3.39 Silver/silver chloride reference electrode (Ag/AgCl)
10 - 1.3.40 Stray current
10 - 1.3.41 Structure
10 - 1.3.42 Structure potential
10 - 1.3.43 Structure potential shift
10 - 1.3.44 Sulfate-reducing bacteria
10 - 1.3.45 Test point
11 - SECTION 2 DESIGN OF STRUCTURES FOR CATHODIC PROTECTION
11 - 2.1 GENERAL
11 - 2.2 STRUCTURE COATING
11 - 2.3 INTERFERENCE WITH FOREIGN STRUCTURES
12 - 2.4 ISOLATION OF STRUCTURES IN CONTACT WITH THE INTERNAL ELECTROLYTE
12 - 2.5 METALLIC CONTINUITY
12 - 2.6 FITTINGS TO SUPPORT ANODES AND MONITORING EQUIPMENT
12 - 2.7 VENTING
13 - SECTION 3 COATINGS FOR USE WITH CATHODIC PROTECTION
13 - 3.1 GENERAL
13 - 3.2 COATING PROPERTIES
13 - 3.2.1 General
14 - 3.2.2 Application and curing properties
14 - 3.2.3 Chemical properties
14 - 3.2.4 Physical properties
14 - 3.3 COATING CHOICE
16 - SECTION 4 CRITERIA FOR CATHODIC PROTECTION
16 - 4.1 GENERAL
16 - 4.2 POTENTIAL CRITERIA FOR FERROUS VESSELS
17 - 4.3 POTENTIAL CRITERIA FOR MIXED METALLIC STRUCTURES
17 - 4.4 OVERPROTECTION
18 - SECTION 5 DESIGN OF CATHODIC PROTECTION SYSTEMS
18 - 5.1 GENERAL
18 - 5.2 SAFETY PRECAUTIONS
18 - 5.3 CHOICE OF SYSTEM-IMPRESSED CURRENT OR GALVANIC ANODES
19 - 5.4 CABLES
19 - 5.4.1 General
19 - 5.4.2 Anode, cathode and test cables
19 - 5.4.3 Test cables
19 - 5.4.4 Impressed current anode cables
20 - 5.4.5 Galvanic anode cables
20 - 5.5 CHECK LIST FOR INITIAL SURVEYS
20 - 5.6 DETERMINATION OF CATHODIC PROTECTION CURRENT REQUIREMENTS
20 - 5.6.1 General
20 - 5.6.2 Basic procedures
21 - 5.6.3 Determination of immersed surface area
21 - 5.6.4 Determination of current density requirements
22 - 5.6.5 Calculation of the current capacity
22 - 5.6.6 Anode layout design
23 - 5.6.7 Galvanic anode mass requirement
24 - 5.7 ANODE ARRANGEMENTS
24 - 5.7.1 General
25 - 5.7.2 Calculation of appropriate anode to structure separation
25 - 5.7.3 Positioning of anodes
26 - 5.8 ANODE MATERIALS, APPLICATION AND OPERATING CHARACTERISTICS
26 - 5.9 POWER SUPPLY CONSIDERATIONS
26 - 5.9.1 Sources of direct current
26 - 5.9.2 Equipment
26 - 5.9.3 Calculation of voltage requirements
27 - 5.10 SYSTEM DESIGN DOCUMENTATION
29 - SECTION 6 INSTALLATION OF CATHODIC PROTECTION SYSTEMS
29 - 6.1 GENERAL
29 - 6.2 MATERIALS AND EQUIPMENT ACCEPTANCE TESTS
29 - 6.2.1 General
29 - 6.2.2 Anodes
29 - 6.2.3 Cables
29 - 6.2.4 Transformer/rectifier equipment
30 - 6.3 INSTALLATION OF GALVANIC ANODE SYSTEMS
30 - 6.4 INSTALLATION OF IMPRESSED CURRENT SYSTEMS
30 - 6.4.1 Anodes and cabling
31 - 6.4.2 Transformer/rectifier
31 - 6.5 REFERENCE ELECTRODES
32 - SECTION 7 OPERATION AND MAINTENANCE OF CATHODIC PROTECTION SYSTEMS
32 - 7.1 GENERAL
32 - 7.2 MEASURING TECHNIQUES
32 - 7.3 COMMISSIONING SURVEY
34 - 7.4 CATHODIC PROTECTION POTENTIAL SURVEYS
34 - 7.5 EQUIPMENT MAINTENANCE CHECKS
34 - 7.5.1 For impressed current systems
34 - 7.5.2 For galvanic anode installations
34 - 7.6 STRUCTURE INSPECTIONS
34 - 7.7 RECORDS
36 - APPENDIX A - GUIDANCE ON THE GENERAL USE OF CATHODIC PROTECTION
36 - A1 SCOPE
36 - A2 GENERAL COMPONENTS OF CATHODIC PROTECTION INSTALLATIONS
36 - A3 FACTORS AFFECTING THE CORROSION OF METALLIC STRUCTURES
39 - APPENDIX B - COMPARISON OF STRUCTURE/ELECTROLYTE POTENTIALS OBTAINED WHEN MEASURED WITH VARIOUS REFERENCE ELECTRODES
39 - B1 SCOPE
40 - APPENDIX C - CONTROL OF INTERFERENCE CURRENTS-LIST OF ELECTROLYSIS COMMITTEES

Provides guidelines for the cathodic protection of internal surfaces of pipes and structures and gives information on the design, installation, operation and maintenance of cathodic protection systems.

This Standard provides guidelines for the cathodic protection of internal surfaces of pipes and structures including heat exchangers, hot water systems, clarifiers, ballast and water storage tanks, cooling conduits and reservoirs, that are in contact with natural waters including seawater and waters of near neutral pH.The Standard specifically covers the following subjects which relate to cathodic protection: (a) The design of structures requiring cathodic protection.(b) Coatings for use on internal surfaces.(c) Criteria for the choice of cathodic protection potential. (d) The design of cathodic protection systems.(e) The installation of cathodic protection systems.(f) The operation and maintenance of cathodic protection systems.NOTES:1 Guidance on the general use and design of cathodic protection systems and factors affecting the corrosion of internal surfaces are given in Appendix A.2 This Standard employs conventional (positive) current flow, for consistency with accepted practice, and uses the potential sign conventions specified in AS 1852. In order to understand the various electrochemical reactions which occur at electrodes during cathodic protection, it should be recognized that electron flow occurs in the opposite direction to conventional currect flow.

First published as AS 2832.4-1994.