HANDBOOK ELECTRICAL ENGINEERING CATHODIC PROTECTION
HANDBOOK ELECTRICAL ENGINEERING CATHODIC PROTECTION (marinenotesonline.blogspot.com)
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HANDBOOK ELECTRICAL ENGINEERING CATHODIC PROTECTION (marinenotesonline.blogspot.com)
ELECTRICAL ENGINEERING CATHODIC PROTECTION
CONTENTS
Page
Section 1 INTRODUCTION
1.1 Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Cancellation. . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Related Technical Documents. . . . . . . . . . . . . . . . . 1
Section 2 CATHODIC PROTECTION CONCEPTS
2.1 Corrosion as an Electrochemical Process. . . . . . . . . . . 3
2.1.1 Driving Force. . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.2 The Electrochemical Cell. . . . . . . . . . . . . . . . . . . 3
2.1.2.1 Components of the Electrochemical Cell. . . . . . . . . . . . 3
2.1.2.2 Reactions in an Electrochemical Cell. . . . . . . . . . . . . 3
2.2 The Electrochemical Basis for Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.1 Potentials Required for Cathodic Protection. . . . . . . . . 4
2.3 Practical Application of Cathodic Protection. . . . . . . . . 5
2.3.1 When Cathodic Protection Should Be Considered. . . . . . . . 5
2.3.1.1 Where Feasible. . . . . . . . . . . . . . . . . . . . . . . . 5
2.3.1.2 When Indicated By Experience. . . . . . . . . . . . . . . . . 5
2.3.1.3 As Required By Regulation. . . . . . . . . . . . . . . . . . 5
2.3.2 Functional Requirements for Cathodic Protection . . . . . . . 8
2.3.2.1 Continuity. . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.2.2 Electrolyte. . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.2.3 Source of Current. . . . . . . . . . . . . . . . . . . . . . 8
2.3.2.4 Connection to Structure. . . . . . . . . . . . . . . . . . . 8
2.4 Sacrificial Anode Systems. . . . . . . . . . . . . . . . . . 8
2.4.1 Anode Materials. . . . . . . . . . . . . . . . . . . . . . . 9
2.4.2 Connection to Structure. . . . . . . . . . . . . . . . . . . 10
2.4.3 Other Requirements. . . . . . . . . . . . . . . . . . . . . . 10
2.5 Impressed Current Systems. . . . . . . . . . . . . . . . . . 10
2.5.1 Anode Materials. . . . . . . . . . . . . . . . . . . . . . . 10
2.5.2 Direct Current Power Source. . . . . . . . . . . . . . . . . 10
2.5.3 Connection to Structure. . . . . . . . . . . . . . . . . . . 10
2.5.4 Other Requirements. . . . . . . . . . . . . . . . . . . . . . 11
Section 3 CRITERIA FOR CATHODIC PROTECTION
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Electrical Criteria. . . . . . . . . . . . . . . . . . . . . 13
3.3 Interpretation of Structure-to-Electrolyte
Potential Readings. . . . . . . . . . . . . . . . . . . . . . 13
3.3.1 National Association of Corrosion Engineers
(NACE)Standard RP-01-69. . . . . . . . . . . . . . . . . . . 13
3.3.1.1 Criteria for Steel. . . . . . . . . . . . . . . . . . . . . . 15
3.3.1.2 Criteria for Aluminum. . . . . . . . . . . . . . . . . . . . 15
3.3.1.3 Criteria for Copper. . . . . . . . . . . . . . . . . . . . . 15
3.3.1.4 Criteria for Dissimilar Metal Structures. . . . . . . . . . . 15
3.3.2 Other Electrical Criteria. . . . . . . . . . . . . . . . . . 15
3.3.2.1 Criteria for Lead. . . . . . . . . . . . . . . . . . . . . . 16
3.3.2.2 NACE RP-02-85. . . . . . . . . . . . . . . . . . . . . . . . 16
3.4 Failure Rate Analysis. . . . . . . . . . . . . . . . . . . . 16
3.5 Nondestructive Testing of Facility. . . . . . . . . . . . . . 16
3.5.1 Visual Analysis. . . . . . . . . . . . . . . . . . . . . . . 16
3.6 Consequences of Underprotection. . . . . . . . . . . . . . . 17
3.7 Consequences of Overprotection. . . . . . . . . . . . . . . . 18
3.7.1 Coating Disbondment. . . . . . . . . . . . . . . . . . . . . 18
3.7.2 Hydrogen Embrittlement. . . . . . . . . . . . . . . . . . . . 18
Section 4 CATHODIC PROTECTION SYSTEM DESIGN PRINCIPLES
4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 General Design Procedures. . . . . . . . . . . . . . . . . . 19
4.2.1 Drawings and Specifications. . . . . . . . . . . . . . . . . 19
4.2.1.1 Drawings and Specifications for the Structure to
be Protected. . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.1.2 Site Drawings. . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.2 Field Surveys. . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2.1 Water Analysis. . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2.2 Soil Characteristics. . . . . . . . . . . . . . . . . . . . . 20
4.2.2.3 Current Requirement Tests. . . . . . . . . . . . . . . . . . 21
4.2.2.4 Location of Other Structures in the Area. . . . . . . . . . . 22
4.2.2.5 Availability of ac Power. . . . . . . . . . . . . . . . . . . 22
4.2.3 Current Requirements. . . . . . . . . . . . . . . . . . . . . 22
4.2.4 Choice of Sacrificial or Impressed Current
System. . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2.5 Basic Design Procedure for Sacrificial Anode
Systems. . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.6 Basic Design Procedure for Impressed Current
Systems. . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.2.6.1 Total Current Determination. . . . . . . . . . . . . . . . . 24
4.2.6.2 Total Resistance Determination. . . . . . . . . . . . . . . . 26
4.2.6.3 Voltage and Rectifier Determination. . . . . . . . . . . . . 27
4.2.7 Analysis of Design Factors. . . . . . . . . . . . . . . . . . 28
4.3 Determination of Field Data. . . . . . . . . . . . . . . . . 28
4.3.1 Determination of Electrolyte Resistivity . . . . . . . . . . 29
4.3.1.1 In Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.1.2 Liquids. . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.2 Chemical Analysis of the Environment . . . . . . . . . . . . 31
4.3.2.1 pH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.3.3 Coating Conductance. . . . . . . . . . . . . . . . . . . . . 31
4.3.3.1 Short Line Method. . . . . . . . . . . . . . . . . . . . . . 33
4.3.3.2 Long Line Method. . . . . . . . . . . . . . . . . . . . . . . 33
4.3.4 Continuity Testing. . . . . . . . . . . . . . . . . . . . . . 35
4.3.4.1 Method 1. . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.4.2 Method 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.4.3 Method 3. . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.5 Insulation Testing. . . . . . . . . . . . . . . . . . . . . . 35
4.3.5.1 Buried Structures. . . . . . . . . . . . . . . . . . . . . . 35
4.3.5.2 Aboveground Structures. . . . . . . . . . . . . . . . . . . . 38
4.4 Corrosion Survey Checklist. . . . . . . . . . . . . . . . . . 38
Section 5 PRECAUTIONS FOR CATHODIC PROTECTION SYSTEM DESIGN
5.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 39
5.2 Excessive Currents and Voltages. . . . . . . . . . . . . . . 39
5.2.1 Interference. . . . . . . . . . . . . . . . . . . . . . . . . 39
5.2.1.1 Detecting Interference. . . . . . . . . . . . . . . . . . . . 41
5.2.1.2 Control of Interference - Anode Bed Location. . . . . . . . . 43
5.2.1.3 Control of Interference - Direct Bonding. . . . . . . . . . . 43
5.2.1.4 Control of Interference - Resistive Bonding. . . . . . . . . 45
5.2.1.5 Control of Interference - Sacrificial Anodes. . . . . . . . . 47
5.2.2 Effects of High Current Density. . . . . . . . . . . . . . . 47
5.2.3 Effects of Electrolyte pH. . . . . . . . . . . . . . . . . . 47
5.3 Hazards Associated with Cathodic Protection. . . . . . . . . 49
5.3.1 Explosive Hazards. . . . . . . . . . . . . . . . . . . . . . 49
5.3.2 Bonding for Electrical Safety. . . . . . . . . . . . . . . . 49
5.3.3 Induced Alternating Currents. . . . . . . . . . . . . . . . . 50
Section 6 IMPRESSED CURRENT SYSTEM
6.1 Advantages of Impressed Current Cathodic
Protection Systems. . . . . . . . . . . . . . . . . . . . . . 53
6.2 Determination of Circuit Resistance. . . . . . . . . . . . . 53
6.2.1 Anode-to-Electrolyte Resistance. . . . . . . . . . . . . . . 53
6.2.1.1 Effect on System Design and Performance. . . . . . . . . . . 53
6.2.1.2 Calculation of Anode-to-Electrolyte Resistance . . . . . . . 54
6.2.1.3 Basic Equations . . . . . . . . . . . . . . . . . . . . . . . 54
6.2.1.4 Simplified Expressions for Common Situations. . . . . . . . . 55
6.2.1.5 Field Measurement. . . . . . . . . . . . . . . . . . . . . . 57
6.2.1.6 Effect of Backfill. . . . . . . . . . . . . . . . . . . . . . 58
6.2.2 Structure-to-Electrolyte Resistance. . . . . . . . . . . . . 59
6.2.3 Connecting Cable Resistance. . . . . . . . . . . . . . . . . 59
6.2.4 Resistance of Connections and Splices. . . . . . . . . . . . 59
6.3 Determination of Power Supply Requirements. . . . . . . . . . 59
6.4 Selection of Power Supply Type. . . . . . . . . . . . . . . . 60
6.4.1 Rectifiers. . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.4.2 Thermoelectric Generators. . . . . . . . . . . . . . . . . . 60
6.4.3 Solar. . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.4.4 Batteries. . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.4.5 Generators. . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.5 Rectifier Selection. . . . . . . . . . . . . . . . . . . . . 60
6.5.1 Rectifier Components. . . . . . . . . . . . . . . . . . . . . 61
6.5.1.1 Transformer Component. . . . . . . . . . . . . . . . . . . . 61
6.5.1.2 Rectifying Elements. . . . . . . . . . . . . . . . . . . . . 61
6.5.1.3 Overload Protection. . . . . . . . . . . . . . . . . . . . . 61
6.5.1.4 Meters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
6.5.2 Standard Rectifier Types . . . . . . . . . . . . . . . . . . 63
6.5.2.1 Single-Phase Bridge. . . . . . . . . . . . . . . . . . . . . 63
6.5.2.2 Single-Phase Center Tap. . . . . . . . . . . . . . . . . . . 63
6.5.2.3 Three-Phase Bridge. . . . . . . . . . . . . . . . . . . . . . 63
6.5.2.4 Three-Phase Wye. . . . . . . . . . . . . . . . . . . . . . . 65
6.5.2.5 Special Rectifier Types . . . . . . . . . . . . . . . . . . . 65
6.5.3 Rectifier Selection and Specifications. . . . . . . . . . . . 68
6.5.3.1 Available Features. . . . . . . . . . . . . . . . . . . . . . 69
6.5.3.2 Air Cooled Versus Oil Immersed. . . . . . . . . . . . . . . . 69
6.5.3.3 Selecting ac Voltage. . . . . . . . . . . . . . . . . . . . . 70
6.5.3.4 dc Voltage and Current Output. . . . . . . . . . . . . . . . 70
CONTENTS
Page
Section 1 INTRODUCTION
1.1 Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Cancellation. . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Related Technical Documents. . . . . . . . . . . . . . . . . 1
Section 2 CATHODIC PROTECTION CONCEPTS
2.1 Corrosion as an Electrochemical Process. . . . . . . . . . . 3
2.1.1 Driving Force. . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.2 The Electrochemical Cell. . . . . . . . . . . . . . . . . . . 3
2.1.2.1 Components of the Electrochemical Cell. . . . . . . . . . . . 3
2.1.2.2 Reactions in an Electrochemical Cell. . . . . . . . . . . . . 3
2.2 The Electrochemical Basis for Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.1 Potentials Required for Cathodic Protection. . . . . . . . . 4
2.3 Practical Application of Cathodic Protection. . . . . . . . . 5
2.3.1 When Cathodic Protection Should Be Considered. . . . . . . . 5
2.3.1.1 Where Feasible. . . . . . . . . . . . . . . . . . . . . . . . 5
2.3.1.2 When Indicated By Experience. . . . . . . . . . . . . . . . . 5
2.3.1.3 As Required By Regulation. . . . . . . . . . . . . . . . . . 5
2.3.2 Functional Requirements for Cathodic Protection . . . . . . . 8
2.3.2.1 Continuity. . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.2.2 Electrolyte. . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.2.3 Source of Current. . . . . . . . . . . . . . . . . . . . . . 8
2.3.2.4 Connection to Structure. . . . . . . . . . . . . . . . . . . 8
2.4 Sacrificial Anode Systems. . . . . . . . . . . . . . . . . . 8
2.4.1 Anode Materials. . . . . . . . . . . . . . . . . . . . . . . 9
2.4.2 Connection to Structure. . . . . . . . . . . . . . . . . . . 10
2.4.3 Other Requirements. . . . . . . . . . . . . . . . . . . . . . 10
2.5 Impressed Current Systems. . . . . . . . . . . . . . . . . . 10
2.5.1 Anode Materials. . . . . . . . . . . . . . . . . . . . . . . 10
2.5.2 Direct Current Power Source. . . . . . . . . . . . . . . . . 10
2.5.3 Connection to Structure. . . . . . . . . . . . . . . . . . . 10
2.5.4 Other Requirements. . . . . . . . . . . . . . . . . . . . . . 11
Section 3 CRITERIA FOR CATHODIC PROTECTION
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Electrical Criteria. . . . . . . . . . . . . . . . . . . . . 13
3.3 Interpretation of Structure-to-Electrolyte
Potential Readings. . . . . . . . . . . . . . . . . . . . . . 13
3.3.1 National Association of Corrosion Engineers
(NACE)Standard RP-01-69. . . . . . . . . . . . . . . . . . . 13
3.3.1.1 Criteria for Steel. . . . . . . . . . . . . . . . . . . . . . 15
3.3.1.2 Criteria for Aluminum. . . . . . . . . . . . . . . . . . . . 15
3.3.1.3 Criteria for Copper. . . . . . . . . . . . . . . . . . . . . 15
3.3.1.4 Criteria for Dissimilar Metal Structures. . . . . . . . . . . 15
3.3.2 Other Electrical Criteria. . . . . . . . . . . . . . . . . . 15
3.3.2.1 Criteria for Lead. . . . . . . . . . . . . . . . . . . . . . 16
3.3.2.2 NACE RP-02-85. . . . . . . . . . . . . . . . . . . . . . . . 16
3.4 Failure Rate Analysis. . . . . . . . . . . . . . . . . . . . 16
3.5 Nondestructive Testing of Facility. . . . . . . . . . . . . . 16
3.5.1 Visual Analysis. . . . . . . . . . . . . . . . . . . . . . . 16
3.6 Consequences of Underprotection. . . . . . . . . . . . . . . 17
3.7 Consequences of Overprotection. . . . . . . . . . . . . . . . 18
3.7.1 Coating Disbondment. . . . . . . . . . . . . . . . . . . . . 18
3.7.2 Hydrogen Embrittlement. . . . . . . . . . . . . . . . . . . . 18
Section 4 CATHODIC PROTECTION SYSTEM DESIGN PRINCIPLES
4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 General Design Procedures. . . . . . . . . . . . . . . . . . 19
4.2.1 Drawings and Specifications. . . . . . . . . . . . . . . . . 19
4.2.1.1 Drawings and Specifications for the Structure to
be Protected. . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.1.2 Site Drawings. . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.2 Field Surveys. . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2.1 Water Analysis. . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2.2 Soil Characteristics. . . . . . . . . . . . . . . . . . . . . 20
4.2.2.3 Current Requirement Tests. . . . . . . . . . . . . . . . . . 21
4.2.2.4 Location of Other Structures in the Area. . . . . . . . . . . 22
4.2.2.5 Availability of ac Power. . . . . . . . . . . . . . . . . . . 22
4.2.3 Current Requirements. . . . . . . . . . . . . . . . . . . . . 22
4.2.4 Choice of Sacrificial or Impressed Current
System. . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2.5 Basic Design Procedure for Sacrificial Anode
Systems. . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.6 Basic Design Procedure for Impressed Current
Systems. . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.2.6.1 Total Current Determination. . . . . . . . . . . . . . . . . 24
4.2.6.2 Total Resistance Determination. . . . . . . . . . . . . . . . 26
4.2.6.3 Voltage and Rectifier Determination. . . . . . . . . . . . . 27
4.2.7 Analysis of Design Factors. . . . . . . . . . . . . . . . . . 28
4.3 Determination of Field Data. . . . . . . . . . . . . . . . . 28
4.3.1 Determination of Electrolyte Resistivity . . . . . . . . . . 29
4.3.1.1 In Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.1.2 Liquids. . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.2 Chemical Analysis of the Environment . . . . . . . . . . . . 31
4.3.2.1 pH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.3.3 Coating Conductance. . . . . . . . . . . . . . . . . . . . . 31
4.3.3.1 Short Line Method. . . . . . . . . . . . . . . . . . . . . . 33
4.3.3.2 Long Line Method. . . . . . . . . . . . . . . . . . . . . . . 33
4.3.4 Continuity Testing. . . . . . . . . . . . . . . . . . . . . . 35
4.3.4.1 Method 1. . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.4.2 Method 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.4.3 Method 3. . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.5 Insulation Testing. . . . . . . . . . . . . . . . . . . . . . 35
4.3.5.1 Buried Structures. . . . . . . . . . . . . . . . . . . . . . 35
4.3.5.2 Aboveground Structures. . . . . . . . . . . . . . . . . . . . 38
4.4 Corrosion Survey Checklist. . . . . . . . . . . . . . . . . . 38
Section 5 PRECAUTIONS FOR CATHODIC PROTECTION SYSTEM DESIGN
5.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 39
5.2 Excessive Currents and Voltages. . . . . . . . . . . . . . . 39
5.2.1 Interference. . . . . . . . . . . . . . . . . . . . . . . . . 39
5.2.1.1 Detecting Interference. . . . . . . . . . . . . . . . . . . . 41
5.2.1.2 Control of Interference - Anode Bed Location. . . . . . . . . 43
5.2.1.3 Control of Interference - Direct Bonding. . . . . . . . . . . 43
5.2.1.4 Control of Interference - Resistive Bonding. . . . . . . . . 45
5.2.1.5 Control of Interference - Sacrificial Anodes. . . . . . . . . 47
5.2.2 Effects of High Current Density. . . . . . . . . . . . . . . 47
5.2.3 Effects of Electrolyte pH. . . . . . . . . . . . . . . . . . 47
5.3 Hazards Associated with Cathodic Protection. . . . . . . . . 49
5.3.1 Explosive Hazards. . . . . . . . . . . . . . . . . . . . . . 49
5.3.2 Bonding for Electrical Safety. . . . . . . . . . . . . . . . 49
5.3.3 Induced Alternating Currents. . . . . . . . . . . . . . . . . 50
Section 6 IMPRESSED CURRENT SYSTEM
6.1 Advantages of Impressed Current Cathodic
Protection Systems. . . . . . . . . . . . . . . . . . . . . . 53
6.2 Determination of Circuit Resistance. . . . . . . . . . . . . 53
6.2.1 Anode-to-Electrolyte Resistance. . . . . . . . . . . . . . . 53
6.2.1.1 Effect on System Design and Performance. . . . . . . . . . . 53
6.2.1.2 Calculation of Anode-to-Electrolyte Resistance . . . . . . . 54
6.2.1.3 Basic Equations . . . . . . . . . . . . . . . . . . . . . . . 54
6.2.1.4 Simplified Expressions for Common Situations. . . . . . . . . 55
6.2.1.5 Field Measurement. . . . . . . . . . . . . . . . . . . . . . 57
6.2.1.6 Effect of Backfill. . . . . . . . . . . . . . . . . . . . . . 58
6.2.2 Structure-to-Electrolyte Resistance. . . . . . . . . . . . . 59
6.2.3 Connecting Cable Resistance. . . . . . . . . . . . . . . . . 59
6.2.4 Resistance of Connections and Splices. . . . . . . . . . . . 59
6.3 Determination of Power Supply Requirements. . . . . . . . . . 59
6.4 Selection of Power Supply Type. . . . . . . . . . . . . . . . 60
6.4.1 Rectifiers. . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.4.2 Thermoelectric Generators. . . . . . . . . . . . . . . . . . 60
6.4.3 Solar. . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.4.4 Batteries. . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.4.5 Generators. . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.5 Rectifier Selection. . . . . . . . . . . . . . . . . . . . . 60
6.5.1 Rectifier Components. . . . . . . . . . . . . . . . . . . . . 61
6.5.1.1 Transformer Component. . . . . . . . . . . . . . . . . . . . 61
6.5.1.2 Rectifying Elements. . . . . . . . . . . . . . . . . . . . . 61
6.5.1.3 Overload Protection. . . . . . . . . . . . . . . . . . . . . 61
6.5.1.4 Meters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
6.5.2 Standard Rectifier Types . . . . . . . . . . . . . . . . . . 63
6.5.2.1 Single-Phase Bridge. . . . . . . . . . . . . . . . . . . . . 63
6.5.2.2 Single-Phase Center Tap. . . . . . . . . . . . . . . . . . . 63
6.5.2.3 Three-Phase Bridge. . . . . . . . . . . . . . . . . . . . . . 63
6.5.2.4 Three-Phase Wye. . . . . . . . . . . . . . . . . . . . . . . 65
6.5.2.5 Special Rectifier Types . . . . . . . . . . . . . . . . . . . 65
6.5.3 Rectifier Selection and Specifications. . . . . . . . . . . . 68
6.5.3.1 Available Features. . . . . . . . . . . . . . . . . . . . . . 69
6.5.3.2 Air Cooled Versus Oil Immersed. . . . . . . . . . . . . . . . 69
6.5.3.3 Selecting ac Voltage. . . . . . . . . . . . . . . . . . . . . 70
6.5.3.4 dc Voltage and Current Output. . . . . . . . . . . . . . . . 70
6.5.3.5 Filters. . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6.5.3.6 Explosion Proof Rectifiers. . . . . . . . . . . . . . . . . . 70
6.5.3.7 Lightning Arresters. . . . . . . . . . . . . . . . . . . . . 71
6.5.3.8 Selenium Versus Silicon Stacks. . . . . . . . . . . . . . . . 71
6.5.3.9 Other Options. . . . . . . . . . . . . . . . . . . . . . . . 71
6.5.3.10 Rectifier Alternating Current Rating. . . . . . . . . . . . . 71
6.6 Anodes for Impressed Current Systems. . . . . . . . . . . . . 73
6.6.1 Graphite Anodes. . . . . . . . . . . . . . . . . . . . . . . 74
6.6.1.1 Specifications. . . . . . . . . . . . . . . . . . . . . . . . 74
6.6.1.2 Available Sizes. . . . . . . . . . . . . . . . . . . . . . . 74
6.6.1.3 Characteristics. . . . . . . . . . . . . . . . . . . . . . . 77
6.6.1.4 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.6.2 High Silicon Cast Iron. . . . . . . . . . . . . . . . . . . . 78
6.6.3 High Silicon Chromium Bearing Cast Iron
(HSCBCI). . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.6.3.1 Specifications. . . . . . . . . . . . . . . . . . . . . . . . 78
6.6.3.2 Available Sizes. . . . . . . . . . . . . . . . . . . . . . . 79
6.6.3.3 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.6.4 Aluminum. . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.6.5 Platinum. . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.6.6 Platinized Anodes. . . . . . . . . . . . . . . . . . . . . . 79
6.6.6.1 Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.6.6.2 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.6.7 Alloyed Lead. . . . . . . . . . . . . . . . . . . . . . . . . 91
6.7 Other System Components. . . . . . . . . . . . . . . . . . . 91
6.7.1 Connecting Cables. . . . . . . . . . . . . . . . . . . . . . 91
6.7.1.1 Factors to be Considered. . . . . . . . . . . . . . . . . . . 91
6.7.1.2 Insulation. . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.7.1.3 Recommended Cables for Specific Applications. . . . . . . . . 93
6.7.1.4 Economic Wire Size. . . . . . . . . . . . . . . . . . . . . . 93
6.7.2 Wire Splices and Connections. . . . . . . . . . . . . . . . . 94
6.7.3 Test Stations. . . . . . . . . . . . . . . . . . . . . . . . 96
6.7.4 Bonds. . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6.7.5 Insulating Joints. . . . . . . . . . . . . . . . . . . . . . 96
Section 7 SACRIFICIAL ANODE SYSTEM DESIGN
7.1 Theory of Operation. . . . . . . . . . . . . . . . . . . . . 113
7.1.1 Advantages of Sacrificial Anode Cathodic
Protection Systems. . . . . . . . . . . . . . . . . . . . . . 113
7.1.2 Disadvantages of Sacrificial Anode Cathodic
Protection Systems. . . . . . . . . . . . . . . . . . . . . . 113
7.2 Sacrificial Anode Cathodic Protection System
DesignProcedures. . . . . . . . . . . . . . . . . . . . . . . 113
7.3 Determination of Current Required for
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
7.4 Determination of Anode Output. . . . . . . . . . . . . . . . 114
7.4.1 Simplified Method for Common Situations. . . . . . . . . . . 114
7.4.2 Determination of Output Using
Anode-to-Electrolyte Resistance. . . . . . . . . . . . . . . 114
7.4.2.1 Calculation of Anode-to-Electrolyte Resistance. . . . . . . . 114
7.4.2.2 Determination of Structure-to-Electrolyte
Resistance. . . . . . . . . . . . . . . . . . . . . . . . . 115
7.4.2.3 Connecting Cable Resistance. . . . . . . . . . . . . . . . . 115
7.4.2.4 Resistance of Connections and Splices. . . . . . . . . . . . 115
7.4.2.5 Total Circuit Resistance. . . . . . . . . . . . . . . . . . . 115
7.4.2.6 Anode-to-Structure Potential. . . . . . . . . . . . . . . . . 115
7.4.2.7 Anode Output Current. . . . . . . . . . . . . . . . . . . . . 115
7.4.3 Field Measurement of Anode Output. . . . . . . . . . . . . . 116
7.5 Determination of Number of Anodes Required. . . . . . . . . . 116
7.6 Determination of Anode Life. . . . . . . . . . . . . . . . . 116
7.7 Seasonal Variation in Anode Output. . . . . . . . . . . . . . 117
7.8 Sacrificial Anode Materials . . . . . . . . . . . . . . . . . 117
7.8.1 Magnesium. . . . . . . . . . . . . . . . . . . . . . . . . . 117
7.8.1.1 Composition. . . . . . . . . . . . . . . . . . . . . . . . . 118
7.8.1.2 Anode Efficiency. . . . . . . . . . . . . . . . . . . . . . . 118
7.8.1.3 Potentials. . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.1.4 Sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.1.5 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.1.6 Backfill. . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.2 Zinc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.2.1 Composition. . . . . . . . . . . . . . . . . . . . . . . . . 125
7.8.2.2 Anode Efficiency. . . . . . . . . . . . . . . . . . . . . . . 125
7.8.2.3 Potentials. . . . . . . . . . . . . . . . . . . . . . . . . . 125
7.8.2.4 Sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.2.5 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.2.6 Backfill. . . . . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.3 Aluminum. . . . . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.3.1 Composition. . . . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.2 Anode Efficiency. . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.3 Potentials. . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.4 Sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.5 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 127
7.9 Other System Components . . . . . . . . . . . . . . . . . . . 127
7.9.1 Connecting Wires. . . . . . . . . . . . . . . . . . . . . . . 127
7.9.1.1 Determination of Connecting Wire Size and Type. . . . . . . . 133
7.9.2 Connections and Splices. . . . . . . . . . . . . . . . . . . 134
7.9.3 Bonds and Insulating Joints. . . . . . . . . . . . . . . . . 134
7.9.4 Test Station Location and Function. . . . . . . . . . . . . . 134
7.9.5 Backfill. . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Section 8 TYPICAL CATHODIC PROTECTION
8.1 Diagrams of Cathodic Protection Systems. . . . . . . . . . . 137
Section 9 CATHODIC PROTECTION SYSTEM DESIGN EXAMPLES
9.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 155
9.2 Elevated Steel Water Tank. . . . . . . . . . . . . . . . . . 155
9.2.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 156
9.2.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 156
9.3 Elevated Water Tank (Where Ice is Expected). . . . . . . . . 173
9.3.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 176
9.3.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 176
9.4 Steel Gas Main. . . . . . . . . . . . . . . . . . . . . . . . 177
9.4.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 180
9.4.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 180
9.5 Gas Distribution System. . . . . . . . . . . . . . . . . . . 184
9.5.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 185
6.5.3.7 Lightning Arresters. . . . . . . . . . . . . . . . . . . . . 71
6.5.3.8 Selenium Versus Silicon Stacks. . . . . . . . . . . . . . . . 71
6.5.3.9 Other Options. . . . . . . . . . . . . . . . . . . . . . . . 71
6.5.3.10 Rectifier Alternating Current Rating. . . . . . . . . . . . . 71
6.6 Anodes for Impressed Current Systems. . . . . . . . . . . . . 73
6.6.1 Graphite Anodes. . . . . . . . . . . . . . . . . . . . . . . 74
6.6.1.1 Specifications. . . . . . . . . . . . . . . . . . . . . . . . 74
6.6.1.2 Available Sizes. . . . . . . . . . . . . . . . . . . . . . . 74
6.6.1.3 Characteristics. . . . . . . . . . . . . . . . . . . . . . . 77
6.6.1.4 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.6.2 High Silicon Cast Iron. . . . . . . . . . . . . . . . . . . . 78
6.6.3 High Silicon Chromium Bearing Cast Iron
(HSCBCI). . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.6.3.1 Specifications. . . . . . . . . . . . . . . . . . . . . . . . 78
6.6.3.2 Available Sizes. . . . . . . . . . . . . . . . . . . . . . . 79
6.6.3.3 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.6.4 Aluminum. . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.6.5 Platinum. . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.6.6 Platinized Anodes. . . . . . . . . . . . . . . . . . . . . . 79
6.6.6.1 Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.6.6.2 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.6.7 Alloyed Lead. . . . . . . . . . . . . . . . . . . . . . . . . 91
6.7 Other System Components. . . . . . . . . . . . . . . . . . . 91
6.7.1 Connecting Cables. . . . . . . . . . . . . . . . . . . . . . 91
6.7.1.1 Factors to be Considered. . . . . . . . . . . . . . . . . . . 91
6.7.1.2 Insulation. . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.7.1.3 Recommended Cables for Specific Applications. . . . . . . . . 93
6.7.1.4 Economic Wire Size. . . . . . . . . . . . . . . . . . . . . . 93
6.7.2 Wire Splices and Connections. . . . . . . . . . . . . . . . . 94
6.7.3 Test Stations. . . . . . . . . . . . . . . . . . . . . . . . 96
6.7.4 Bonds. . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6.7.5 Insulating Joints. . . . . . . . . . . . . . . . . . . . . . 96
Section 7 SACRIFICIAL ANODE SYSTEM DESIGN
7.1 Theory of Operation. . . . . . . . . . . . . . . . . . . . . 113
7.1.1 Advantages of Sacrificial Anode Cathodic
Protection Systems. . . . . . . . . . . . . . . . . . . . . . 113
7.1.2 Disadvantages of Sacrificial Anode Cathodic
Protection Systems. . . . . . . . . . . . . . . . . . . . . . 113
7.2 Sacrificial Anode Cathodic Protection System
DesignProcedures. . . . . . . . . . . . . . . . . . . . . . . 113
7.3 Determination of Current Required for
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
7.4 Determination of Anode Output. . . . . . . . . . . . . . . . 114
7.4.1 Simplified Method for Common Situations. . . . . . . . . . . 114
7.4.2 Determination of Output Using
Anode-to-Electrolyte Resistance. . . . . . . . . . . . . . . 114
7.4.2.1 Calculation of Anode-to-Electrolyte Resistance. . . . . . . . 114
7.4.2.2 Determination of Structure-to-Electrolyte
Resistance. . . . . . . . . . . . . . . . . . . . . . . . . 115
7.4.2.3 Connecting Cable Resistance. . . . . . . . . . . . . . . . . 115
7.4.2.4 Resistance of Connections and Splices. . . . . . . . . . . . 115
7.4.2.5 Total Circuit Resistance. . . . . . . . . . . . . . . . . . . 115
7.4.2.6 Anode-to-Structure Potential. . . . . . . . . . . . . . . . . 115
7.4.2.7 Anode Output Current. . . . . . . . . . . . . . . . . . . . . 115
7.4.3 Field Measurement of Anode Output. . . . . . . . . . . . . . 116
7.5 Determination of Number of Anodes Required. . . . . . . . . . 116
7.6 Determination of Anode Life. . . . . . . . . . . . . . . . . 116
7.7 Seasonal Variation in Anode Output. . . . . . . . . . . . . . 117
7.8 Sacrificial Anode Materials . . . . . . . . . . . . . . . . . 117
7.8.1 Magnesium. . . . . . . . . . . . . . . . . . . . . . . . . . 117
7.8.1.1 Composition. . . . . . . . . . . . . . . . . . . . . . . . . 118
7.8.1.2 Anode Efficiency. . . . . . . . . . . . . . . . . . . . . . . 118
7.8.1.3 Potentials. . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.1.4 Sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.1.5 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.1.6 Backfill. . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.2 Zinc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.8.2.1 Composition. . . . . . . . . . . . . . . . . . . . . . . . . 125
7.8.2.2 Anode Efficiency. . . . . . . . . . . . . . . . . . . . . . . 125
7.8.2.3 Potentials. . . . . . . . . . . . . . . . . . . . . . . . . . 125
7.8.2.4 Sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.2.5 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.2.6 Backfill. . . . . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.3 Aluminum. . . . . . . . . . . . . . . . . . . . . . . . . . . 126
7.8.3.1 Composition. . . . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.2 Anode Efficiency. . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.3 Potentials. . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.4 Sizes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.8.3.5 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 127
7.9 Other System Components . . . . . . . . . . . . . . . . . . . 127
7.9.1 Connecting Wires. . . . . . . . . . . . . . . . . . . . . . . 127
7.9.1.1 Determination of Connecting Wire Size and Type. . . . . . . . 133
7.9.2 Connections and Splices. . . . . . . . . . . . . . . . . . . 134
7.9.3 Bonds and Insulating Joints. . . . . . . . . . . . . . . . . 134
7.9.4 Test Station Location and Function. . . . . . . . . . . . . . 134
7.9.5 Backfill. . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Section 8 TYPICAL CATHODIC PROTECTION
8.1 Diagrams of Cathodic Protection Systems. . . . . . . . . . . 137
Section 9 CATHODIC PROTECTION SYSTEM DESIGN EXAMPLES
9.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 155
9.2 Elevated Steel Water Tank. . . . . . . . . . . . . . . . . . 155
9.2.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 156
9.2.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 156
9.3 Elevated Water Tank (Where Ice is Expected). . . . . . . . . 173
9.3.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 176
9.3.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 176
9.4 Steel Gas Main. . . . . . . . . . . . . . . . . . . . . . . . 177
9.4.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 180
9.4.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 180
9.5 Gas Distribution System. . . . . . . . . . . . . . . . . . . 184
9.5.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 185
9.5.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 185
9.6 Black Iron, Hot Water Storage Tank. . . . . . . . . . . . . . 187
9.6.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 188
9.6.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 188
9.7 Underground Steel Storage Tank. . . . . . . . . . . . . . . . 190
9.7.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 190
9.7.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 192
9.8 Heating Distribution System. . . . . . . . . . . . . . . . . 192
9.8.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 192
9.8.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 193
9.8.3 Groundbed Design . . . . . . . . . . . . . . . . . . . . . . 194
9.8.4 Rectifier Location. . . . . . . . . . . . . . . . . . . . . . 195
9.9 Aircraft Multiple Hydrant Refueling System. . . . . . . . . . 195
9.9.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 195
9.9.2 Computations. . . . . . . . . . . . . . . . . . . . . . . . . 196
9.10 Steel Sheet Piling in Seawater (Galvanic nodes). . . . . . . 199
9.10.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 199
9.10.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 201
9.11 Steel Sheet Piling in Seawater (Impressed
Current
9.11.1 Design Data. . . . . . . . . . . . . . . . . . . . . . . . . 203
9.11.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 203
9.12 Steel H Piling in Seawater (Galvanic Anodes). . . . . . . . . 207
9.12.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 208
9.12.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 208
9.13 Steel H Piling in Seawater (Impressed Current). . . . . . . . 210
9.13.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 210
9.13.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 210
Section 10 INSTALLATION AND CONSTRUCTION PRACTICES
10.1 Factors to Consider. . . . . . . . . . . . . . . . . . . . . 213
10.2 Planning of Construction. . . . . . . . . . . . . . . . . . . 213
10.3 Pipeline Coating. . . . . . . . . . . . . . . . . . . . . . . 213
10.3.1 Over-the-Ditch Coating. . . . . . . . . . . . . . . . . . . . 213
10.3.2 Yard Applied Coating. . . . . . . . . . . . . . . . . . . . . 213
10.3.3 Joint and Damage Repair. . . . . . . . . . . . . . . . . . . 214
10.3.4 Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . 214
10.4 Coatings for Other Structures. . . . . . . . . . . . . . . . 214
10.5 Pipeline Installation. . . . . . . . . . . . . . . . . . . . 214
10.5.1 Casings. . . . . . . . . . . . . . . . . . . . . . . . . . . 214
10.5.2 Foreign Pipeline Crossings. . . . . . . . . . . . . . . . . . 215
10.5.3 Insulating Joints. . . . . . . . . . . . . . . . . . . . . . 215
10.5.4 Bonds. . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
10.6 Electrical Connections. . . . . . . . . . . . . . . . . . . . 216
10.7 Test Stations. . . . . . . . . . . . . . . . . . . . . . . . 216
10.8 Sacrificial Anode Installation. . . . . . . . . . . . . . . . 216
10.8.1 Vertical. . . . . . . . . . . . . . . . . . . . . . . . . . . 216
10.8.2 Horizontal. . . . . . . . . . . . . . . . . . . . . . . . . . 217
10.9 Impressed Current Anode Installation. . . . . . . . . . . . . 217
10.9.1 Vertical. . . . . . . . . . . . . . . . . . . . . . . . . . . 219
10.9.2 Horizontal. . . . . . . . . . . . . . . . . . . . . . . . . . 219
10.9.3 Deep Anode Beds. . . . . . . . . . . . . . . . . . . . . . . 219
10.9.4 Other Anode Types. . . . . . . . . . . . . . . . . . . . . . 225
10.9.5 Connections. . . . . . . . . . . . . . . . . . . . . . . . . 225
10.10 Impressed Current Rectifier Installation. . . . . . . . . . . 225
Section 11 SYSTEM CHECKOUT AND INITIAL ADJUSTMENTS
11.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 229
11.2 Initial Potential Survey. . . . . . . . . . . . . . . . . . . 229
11.3 Detection and Correction of Interference. . . . . . . . . . . 229
11.4 Adjustment of Impressed Current Systems. . . . . . . . . . . 229
11.4.1 Uneven Structure-To-Electrolyte Potentials. . . . . . . . . . 229
11.4.2 Rectifier Voltage and Current Capacity. . . . . . . . . . . . 230
11.5 Adjustment of Sacrificial Anode Systems. . . . . . . . . . . 230
11.5.1 Low Anode Current Levels. . . . . . . . . . . . . . . . . . . 230
11.5.2 Inadequate Protection at Designed Current Levels . . . . . . 230
Section 12 MAINTAINING CATHODIC PROTECTION
12.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 231
12.2 Required Periodic Monitoring and Maintenance. . . . . . . . . 231
12.3 Design Data Required for System Maintenance. . . . . . . . . 231
12.3.1 Drawings. . . . . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.2 System Data. . . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.2.1 Design Potentials. . . . . . . . . . . . . . . . . . . . . . 231
12.3.2.2 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.2.3 System Settings and Potential Readings. . . . . . . . . . . . 231
12.3.2.4 Rectifier Instructions. . . . . . . . . . . . . . . . . . . . 232
12.4 Basic Maintenance Requirements. . . . . . . . . . . . . . . . 232
12.5 Guidance for Maintenance . . . . . . . . . . . . . . . . . . 232
12.5.1 Agency Maintenance and Operations Manuals. . . . . . . . . . 232
12.5.2 DOT Regulations. . . . . . . . . . . . . . . . . . . . . . . 235
12.5.3 NACE Standards. . . . . . . . . . . . . . . . . . . . . . . . 235
Section 13 ECONOMIC ANALYSIS
13.1 Importance of Economic Analysis. . . . . . . . . . . . . . . 237
13.2 Economic Analysis Process. . . . . . . . . . . . . . . . . . 237
13.2.1 Define the Objective. . . . . . . . . . . . . . . . . . . . . 237
13.2.2 Generate Alternatives. . . . . . . . . . . . . . . . . . . . 238
13.2.3 Formulate Assumptions. . . . . . . . . . . . . . . . . . . . 238
13.2.4 Determine Costs and Benefits. . . . . . . . . . . . . . . . . 238
13.2.4.1 Costs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
13.2.4.2 Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . 239
13.2.5 Compare Costs and Benefits and Rank
Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
13.2.6 Perform Sensitivity Analysis. . . . . . . . . . . . . . . . . 239
13.3 Design of Cathodic Protection Systems. . . . . . . . . . . . 239
13.4 Economic Analysis - Example 1 . . . . . . . . . . . . . . . . 240
13.4.1 Objective. . . . . . . . . . . . . . . . . . . . . . . . . . 240
13.4.2 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . 240
13.4.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 240
13.4.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 240
13.4.4.1 Cost - Alternative 1--Steel Line Without
Cathodic Protection. . . . . . . . . . . . . . . . . . . . . 240
13.4.4.2 Cost - Alternative 2--Steel Line with Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . 242
13.4.4.3 Cost - Alternative 3--Plastic Line. . . . . . . . . . . . . . 242
13.4.4.4 Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.4.5 Compare Costs/Benefits . . . . . . . . . . . . . . . . . . . 243
13.5 Economic Analysis - Example 2 . . . . . . . . . . . . . . . . 243
13.5.1 Objective. . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.5.2 Alternative . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.5.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.5.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 244
13.5.4.1 Cost - Alternative 1--Steel Line Without
Cathodic Protection. . . . . . . . . . . . . . . . . . . . . 244
13.5.4.2 Cost - Alternative 2--Steel Line With Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . 245
13.5.4.3 Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . 246
13.5.5 Compare Costs/Benefits . . . . . . . . . . . . . . . . . . . 246
13.5.6 Conclusions and Recommendations. . . . . . . . . . . . . . . 247
13.6 Economic Analysis - Example 3 . . . . . . . . . . . . . . . . 247
13.6.1 Objective. . . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.2 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 247
13.6.4.1 Cost - Alternative 1--Impressed Current Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.4.2 Cost - Alternative 2--Galvanic Anode System. . . . . . . . . 248
13.6.5 Compare Costs/Benefits . . . . . . . . . . . . . . . . . . . 249
13.7 Economic Analysis - Example 4 . . . . . . . . . . . . . . . . 249
13.7.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . 249
13.7.2 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . 249
13.7.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 249
13.7.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 249
13.7.4.1 Cost - Alternative 1--Cathodic Protection System
Maintenance Continued. . . . . . . . . . . . . . . . . . . 249
13.7.4.2 Cost - Alternative 2--Cathodic Protection System
Maintenance Discontinued. . . . . . . . . . . . . . . . . . 250
13.7.5 Compare Benefits and Costs . . . . . . . . . . . . . . . . . 251
13.8 Economic Analysis Goal. . . . . . . . . . . . . . . . . . . . 251
Section 14 CORROSION COORDINATING COMMITTEE PARTICIPATION
14.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 253
14.2 Functions of Corrosion Coordinating Committees. . . . . . . . 253
14.3 Operation of the Committees. . . . . . . . . . . . . . . . . 253
14.4 Locations of Committees. . . . . . . . . . . . . . . . . . . 253
APPENDIX
APPENDIX A UNDERGROUND CORROSION SURVEY CHECKLIST . . . . . . . . . . . 255
B ECONOMIC LIFE GUIDELINES . . . . . . . . . . . . . . . . . . 265
C PROJECT YEAR DISCOUNT FACTORS . . . . . . . . . . . . . . . . 267
D PRESENT VALUE FORMULAE . . . . . . . . . . . . . . . . . . . 269
E DOT REGULATIONS . . . . . . . . . . . . . . . . . . . . . . . 271
9.6 Black Iron, Hot Water Storage Tank. . . . . . . . . . . . . . 187
9.6.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 188
9.6.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 188
9.7 Underground Steel Storage Tank. . . . . . . . . . . . . . . . 190
9.7.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 190
9.7.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 192
9.8 Heating Distribution System. . . . . . . . . . . . . . . . . 192
9.8.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 192
9.8.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 193
9.8.3 Groundbed Design . . . . . . . . . . . . . . . . . . . . . . 194
9.8.4 Rectifier Location. . . . . . . . . . . . . . . . . . . . . . 195
9.9 Aircraft Multiple Hydrant Refueling System. . . . . . . . . . 195
9.9.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 195
9.9.2 Computations. . . . . . . . . . . . . . . . . . . . . . . . . 196
9.10 Steel Sheet Piling in Seawater (Galvanic nodes). . . . . . . 199
9.10.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 199
9.10.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 201
9.11 Steel Sheet Piling in Seawater (Impressed
Current
9.11.1 Design Data. . . . . . . . . . . . . . . . . . . . . . . . . 203
9.11.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 203
9.12 Steel H Piling in Seawater (Galvanic Anodes). . . . . . . . . 207
9.12.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 208
9.12.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 208
9.13 Steel H Piling in Seawater (Impressed Current). . . . . . . . 210
9.13.1 Design Data . . . . . . . . . . . . . . . . . . . . . . . . . 210
9.13.2 Computations . . . . . . . . . . . . . . . . . . . . . . . . 210
Section 10 INSTALLATION AND CONSTRUCTION PRACTICES
10.1 Factors to Consider. . . . . . . . . . . . . . . . . . . . . 213
10.2 Planning of Construction. . . . . . . . . . . . . . . . . . . 213
10.3 Pipeline Coating. . . . . . . . . . . . . . . . . . . . . . . 213
10.3.1 Over-the-Ditch Coating. . . . . . . . . . . . . . . . . . . . 213
10.3.2 Yard Applied Coating. . . . . . . . . . . . . . . . . . . . . 213
10.3.3 Joint and Damage Repair. . . . . . . . . . . . . . . . . . . 214
10.3.4 Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . 214
10.4 Coatings for Other Structures. . . . . . . . . . . . . . . . 214
10.5 Pipeline Installation. . . . . . . . . . . . . . . . . . . . 214
10.5.1 Casings. . . . . . . . . . . . . . . . . . . . . . . . . . . 214
10.5.2 Foreign Pipeline Crossings. . . . . . . . . . . . . . . . . . 215
10.5.3 Insulating Joints. . . . . . . . . . . . . . . . . . . . . . 215
10.5.4 Bonds. . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
10.6 Electrical Connections. . . . . . . . . . . . . . . . . . . . 216
10.7 Test Stations. . . . . . . . . . . . . . . . . . . . . . . . 216
10.8 Sacrificial Anode Installation. . . . . . . . . . . . . . . . 216
10.8.1 Vertical. . . . . . . . . . . . . . . . . . . . . . . . . . . 216
10.8.2 Horizontal. . . . . . . . . . . . . . . . . . . . . . . . . . 217
10.9 Impressed Current Anode Installation. . . . . . . . . . . . . 217
10.9.1 Vertical. . . . . . . . . . . . . . . . . . . . . . . . . . . 219
10.9.2 Horizontal. . . . . . . . . . . . . . . . . . . . . . . . . . 219
10.9.3 Deep Anode Beds. . . . . . . . . . . . . . . . . . . . . . . 219
10.9.4 Other Anode Types. . . . . . . . . . . . . . . . . . . . . . 225
10.9.5 Connections. . . . . . . . . . . . . . . . . . . . . . . . . 225
10.10 Impressed Current Rectifier Installation. . . . . . . . . . . 225
Section 11 SYSTEM CHECKOUT AND INITIAL ADJUSTMENTS
11.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 229
11.2 Initial Potential Survey. . . . . . . . . . . . . . . . . . . 229
11.3 Detection and Correction of Interference. . . . . . . . . . . 229
11.4 Adjustment of Impressed Current Systems. . . . . . . . . . . 229
11.4.1 Uneven Structure-To-Electrolyte Potentials. . . . . . . . . . 229
11.4.2 Rectifier Voltage and Current Capacity. . . . . . . . . . . . 230
11.5 Adjustment of Sacrificial Anode Systems. . . . . . . . . . . 230
11.5.1 Low Anode Current Levels. . . . . . . . . . . . . . . . . . . 230
11.5.2 Inadequate Protection at Designed Current Levels . . . . . . 230
Section 12 MAINTAINING CATHODIC PROTECTION
12.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 231
12.2 Required Periodic Monitoring and Maintenance. . . . . . . . . 231
12.3 Design Data Required for System Maintenance. . . . . . . . . 231
12.3.1 Drawings. . . . . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.2 System Data. . . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.2.1 Design Potentials. . . . . . . . . . . . . . . . . . . . . . 231
12.3.2.2 Current Output. . . . . . . . . . . . . . . . . . . . . . . . 231
12.3.2.3 System Settings and Potential Readings. . . . . . . . . . . . 231
12.3.2.4 Rectifier Instructions. . . . . . . . . . . . . . . . . . . . 232
12.4 Basic Maintenance Requirements. . . . . . . . . . . . . . . . 232
12.5 Guidance for Maintenance . . . . . . . . . . . . . . . . . . 232
12.5.1 Agency Maintenance and Operations Manuals. . . . . . . . . . 232
12.5.2 DOT Regulations. . . . . . . . . . . . . . . . . . . . . . . 235
12.5.3 NACE Standards. . . . . . . . . . . . . . . . . . . . . . . . 235
Section 13 ECONOMIC ANALYSIS
13.1 Importance of Economic Analysis. . . . . . . . . . . . . . . 237
13.2 Economic Analysis Process. . . . . . . . . . . . . . . . . . 237
13.2.1 Define the Objective. . . . . . . . . . . . . . . . . . . . . 237
13.2.2 Generate Alternatives. . . . . . . . . . . . . . . . . . . . 238
13.2.3 Formulate Assumptions. . . . . . . . . . . . . . . . . . . . 238
13.2.4 Determine Costs and Benefits. . . . . . . . . . . . . . . . . 238
13.2.4.1 Costs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
13.2.4.2 Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . 239
13.2.5 Compare Costs and Benefits and Rank
Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
13.2.6 Perform Sensitivity Analysis. . . . . . . . . . . . . . . . . 239
13.3 Design of Cathodic Protection Systems. . . . . . . . . . . . 239
13.4 Economic Analysis - Example 1 . . . . . . . . . . . . . . . . 240
13.4.1 Objective. . . . . . . . . . . . . . . . . . . . . . . . . . 240
13.4.2 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . 240
13.4.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 240
13.4.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 240
13.4.4.1 Cost - Alternative 1--Steel Line Without
Cathodic Protection. . . . . . . . . . . . . . . . . . . . . 240
13.4.4.2 Cost - Alternative 2--Steel Line with Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . 242
13.4.4.3 Cost - Alternative 3--Plastic Line. . . . . . . . . . . . . . 242
13.4.4.4 Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.4.5 Compare Costs/Benefits . . . . . . . . . . . . . . . . . . . 243
13.5 Economic Analysis - Example 2 . . . . . . . . . . . . . . . . 243
13.5.1 Objective. . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.5.2 Alternative . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.5.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 243
13.5.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 244
13.5.4.1 Cost - Alternative 1--Steel Line Without
Cathodic Protection. . . . . . . . . . . . . . . . . . . . . 244
13.5.4.2 Cost - Alternative 2--Steel Line With Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . . 245
13.5.4.3 Benefits. . . . . . . . . . . . . . . . . . . . . . . . . . . 246
13.5.5 Compare Costs/Benefits . . . . . . . . . . . . . . . . . . . 246
13.5.6 Conclusions and Recommendations. . . . . . . . . . . . . . . 247
13.6 Economic Analysis - Example 3 . . . . . . . . . . . . . . . . 247
13.6.1 Objective. . . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.2 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 247
13.6.4.1 Cost - Alternative 1--Impressed Current Cathodic
Protection. . . . . . . . . . . . . . . . . . . . . . . . . 247
13.6.4.2 Cost - Alternative 2--Galvanic Anode System. . . . . . . . . 248
13.6.5 Compare Costs/Benefits . . . . . . . . . . . . . . . . . . . 249
13.7 Economic Analysis - Example 4 . . . . . . . . . . . . . . . . 249
13.7.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . 249
13.7.2 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . 249
13.7.3 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 249
13.7.4 Cost/Benefit Analysis . . . . . . . . . . . . . . . . . . . . 249
13.7.4.1 Cost - Alternative 1--Cathodic Protection System
Maintenance Continued. . . . . . . . . . . . . . . . . . . 249
13.7.4.2 Cost - Alternative 2--Cathodic Protection System
Maintenance Discontinued. . . . . . . . . . . . . . . . . . 250
13.7.5 Compare Benefits and Costs . . . . . . . . . . . . . . . . . 251
13.8 Economic Analysis Goal. . . . . . . . . . . . . . . . . . . . 251
Section 14 CORROSION COORDINATING COMMITTEE PARTICIPATION
14.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 253
14.2 Functions of Corrosion Coordinating Committees. . . . . . . . 253
14.3 Operation of the Committees. . . . . . . . . . . . . . . . . 253
14.4 Locations of Committees. . . . . . . . . . . . . . . . . . . 253
APPENDIX
APPENDIX A UNDERGROUND CORROSION SURVEY CHECKLIST . . . . . . . . . . . 255
B ECONOMIC LIFE GUIDELINES . . . . . . . . . . . . . . . . . . 265
C PROJECT YEAR DISCOUNT FACTORS . . . . . . . . . . . . . . . . 267
D PRESENT VALUE FORMULAE . . . . . . . . . . . . . . . . . . . 269
E DOT REGULATIONS . . . . . . . . . . . . . . . . . . . . . . . 271
Figure 1 The Electrochemical Cell . . . . . . . . . . . . . . . . . . 6
2 Corrosion Cell - Zinc and Platinum
in Hydrochloric Acid . . . . . . . . . . . . . . . . . . . 6
3 Cathodic Protection Cell . . . . . . . . . . . . . . . . . . 7
4 Hydraulic Analogy of Cathodic Protection . . . . . . . . . . 7
5 Sacrificial Anode Cathodic Protection/Impressed
Current Cathodic Protection . . . . . . . . . . . . . . . . 9
6 Structure-to Electrolyte Potential Measurement . . . . . . . 14
7 Failure Rate Versus Time . . . . . . . . . . . . . . . . . . 17
8 Temporary Cathodic Protection System for
Determining Current Requirements . . . . . . . . . . . . . 23
9 4-Pin Soil Resistivity Measurement . . . . . . . . . . . . . 30
10 Soil Box for Determination of Resistivity . . . . . . . . . . 30
11 pH Meter . . . . . . . . . . . . . . . . . . . . . . . . . . 32
12 Antimony Electrode Potential Versus pH . . . . . . . . . . . 32
13 Coating Conductance - Short Line Method . . . . . . . . . . . 34
14 Coating Conductance - Long Line Method . . . . . . . . . . . 34
15 Continuity Testing - Potential Method . . . . . . . . . . . . 36
16 Continuity Testing - Potential Drop Method . . . . . . . . . 36
17 Continuity Testing - Pipe Locator Method . . . . . . . . . . 37
18 Insulation Testing - Two-Wire Test Station . . . . . . . . . 37
19 Interference from Impressed Current
Cathodic Protection System . . . . . . . . . . . . . . . . 40
20 Interference Due to Potential Gradients . . . . . . . . . . . 41
21 Interference Testing . . . . . . . . . . . . . . . . . . . . 42
22 Plot of Potentials from Interference Test . . . . . . . . . . 42
23 Measurement of Current Flow in Structure . . . . . . . . . . 44
24 Correction of Interferencce - Direct Bonding . . . . . . . . 44
25 Correction of Interference - Resistive Bonding . . . . . . . 45
26 Effects of Bonding on Interference Test
Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
27 Bonding for Continuity . . . . . . . . . . . . . . . . . . . 48
28 Control of Interference - Sacrificial Anode . . . . . . . . . 48
29 Interference Due to Cathodic Protection of
Quaywall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
30 Correction of Interference - Bonding . . . . . . . . . . . . 51
31 Equavalent Cathodic Protection Circuit . . . . . . . . . . . 54
32 Single-Phase - Full-Wave Bridge Rectifier . . . . . . . . . . 62
33 Full-Wave Rectified Current . . . . . . . . . . . . . . . . . 64
34 Single-Phase - Center Tap Circuit . . . . . . . . . . . . . . 64
35 Three-Phase Bridge Circuit . . . . . . . . . . . . . . . . . 65
36 Three-Phase Wye Circuit . . . . . . . . . . . . . . . . . . . 66
37 Half-Wave Rectified Current . . . . . . . . . . . . . . . . . 66
38 Constant Current Rectifier . . . . . . . . . . . . . . . . . 67
39 Constant Potential Rectifier . . . . . . . . . . . . . . . . 67
40 Multicircuit Constant Current Rectifier . . . . . . . . . . . 68
41 Efficiency Versus Voltage - Selenium Stacks . . . . . . . . . 72
42 Efficiency Versus Voltage - Silicon Stacks . . . . . . . . . 73
43 Anode-to-Cable Connection - Graphite Anode . . . . . . . . . 75
44 Center Connected Graphite Anode . . . . . . . . . . . . . . . 76
45 Duct Anode . . . . . . . . . . . . . . . . . . . . . . . . . 83
46 Button Anode . . . . . . . . . . . . . . . . . . . . . . . . 83
47 Bridge Deck Anode - Type I . . . . . . . . . . . . . . . . . 84
48 Bridge Deck Anode - Type II . . . . . . . . . . . . . . . . . 85
49 Tubular Anode . . . . . . . . . . . . . . . . . . . . . . . . 86
50 Anode to Cable Connection - Epoxy Seal . . . . . . . . . . . 87
51 Anode to Cable Connection - Teflon Seal . . . . . . . . . . . 88
52 Center Connected High Silicon Chromium
Bearing Cast Iron Anode . . . . . . . . . . . . . . . . . . 89
53 Typical Platinized Anode . . . . . . . . . . . . . . . . . . 90
54 Flush-Mounted Potential Test Station . . . . . . . . . . . . 97
55 Soil Contact Test Station . . . . . . . . . . . . . . . . . . 98
56 IR Drop Test Station . . . . . . . . . . . . . . . . . . . . 99
57 Insulating Flange Test Station (Six-Wire) . . . . . . . . . . 100
58 Wiring for Casing Isolation Test Station . . . . . . . . . . 101
59 Bond Test Station . . . . . . . . . . . . . . . . . . . . . . 101
60 Anode Balancing Resistors . . . . . . . . . . . . . . . . . . 102
61 Bonding of a Dresser-Style Coupling . . . . . . . . . . . . . 103
62 Bonding Methods for Cast Iron Bell-and-Spigot
Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
63 Isolating a Protected Line from an Unprotected
Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
64 Electrical Bond . . . . . . . . . . . . . . . . . . . . . . . 106
65 Thermosetting-Resin Pipe Connection . . . . . . . . . . . . . 106
66 Clamp Type Bonding Joint . . . . . . . . . . . . . . . . . . 107
67 Underground Splice . . . . . . . . . . . . . . . . . . . . . 108
68 Welded Type Bonding Joint for Slip-On
Pipe Installed Aboveground . . . . . . . . . . . . . . . . 109
69 Test Box for an Insulating Fitting . . . . . . . . . . . . . 110
70 Steel Insulating Joint Details for Flanged
Pipe Installed Below Grade . . . . . . . . . . . . . . . . 111
71 Steel Insulating Joint Details for Aboveground
Flanged Pipe . . . . . . . . . . . . . . . . . . . . . . . 112
72 Insulating Joint Details for Screwed Pipe
Connections . . . . . . . . . . . . . . . . . . . . . . . . 112
73 Efficiency Versus Current Density - Magnesium
Anodes . . . . . . . . . . . . . . . . . . . . . . . . . . 118
74 Aluminum Alloy Bracelet Anodes . . . . . . . . . . . . . . . 133
75 Current-Potential Test Station . . . . . . . . . . . . . . . 135
76 Typical Building Underground Heat & Water Lines . . . . . . . 138
77 Impressed Current Point Type Cathodic Protection
for Aircraft Hydrant Refueling System . . . . . . . . . . . . 138
78 Galvanic Anode Type Cathodic Protection for
Coated Underground Sewage Lift Station . . . . . . . . . . . 139
79 Zinc Anode on Reinforced Concrete Block . . . . . . . . . . . 140
80 Radiant Heat or Snow-Melting Piping . . . . . . . . . . . . . 141
81 Cathodic Protection of Foundation Piles . . . . . . . . . . . 142
82 Impressed Current Cathodic Protection for
Existing On-Grade Storage Tank . . . . . . . . . . . . . . 142
83 Impressed Current Cathodic Protection with
Horizontal Anodes for On-Grade Storage Tank - New
Installation . . . . . . . . . . . . . . . . . . . . . . . 143
84 On-Grade Fresh Water Tank Using Suspended Anodes . . . . . . 144
85 Open Water Box Cooler . . . . . . . . . . . . . . . . . . . . 144
86 Horizontal Hot Water Tank - Magnesium Anode
Installation . . . . . . . . . . . . . . . . . . . . . . . 145
87 Impressed Current Cathodic Protection System for
Sheet Piling for Wharf Construction . . . . . . . . . . . . 146
88 Suspended Anode Cathodic Protection for H-Piling
in Seawater . . . . . . . . . . . . . . . . . . . . . . . . . 146
89 Cathodic Protection for H-Piling in Seawater . . . . . . . . 147
90 Cellular Earth Fill Pier Supports . . . . . . . . . . . . . . 148
91 Elevated Fresh Water Tank Using Suspended Anodes . . . . . . 149
92 Cathodic Protection of Tanks using Rigid
Floor-Mounted Anodes . . . . . . . . . . . . . . . . . . . 150
93 Cathodic Protection of Hydraulic Elevator
Cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . 151
94 Hydraulic Hoist Cylinder . . . . . . . . . . . . . . . . . . 152
95 Typical Cathodic Protection of Underground Tank
Farm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
96 Gasoline Service Station System . . . . . . . . . . . . . . . 154
97 Segmented Elevated Tank for Area Calculations . . . . . . . . 157
98 Anode Spacing for Elevated Steel Water Tank . . . . . . . . . 160
99 Anode Suspension Arrangement for Elevated
Steel Water Tank . . . . . . . . . . . . . . . . . . . . . 162
100 Equivalent Diameter for Anodes in a
Circle in Water Tank . . . . . . . . . . . . . . . . . . . 163
101 Fringe Factor for Stub Anodes . . . . . . . . . . . . . . . . 164
102 Elevated Steel Water Tank Showing Rectifier and
Anode Arrangement . . . . . . . . . . . . . . . . . . . . . 172
103 Hand Hole and Anode Suspension Detail for
Elevated Water Tank . . . . . . . . . . . . . . . . . . . . . . . . . 174
104 Riser Anode Suspension Detail for Elevated Water
Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
105 Dimensions: Elevated Steel Water Tank . . . . . . . . . . . 175
106 Cathodic Protection for Tanks Using Rigid Mounted . . . . . . 178
Button-Type Anodes and Platinized Titanium Wire
107 Cathodic Protection System for Gas Main . . . . . . . . . . . 179
108 Layout of Gas Piping in Residential District . . . . . . . . 184
109 Cathodic Protection for Black Iron, Hot Water
Storage Tank . . . . . . . . . . . . . . . . . . . . . . . . 187
110 Galvanic Anode Cathodic Protection of
Underground Steel Storage Tank . . . . . . . . . . . . . . . 191
111 Impressed Current Cathodic Protection for
Heating Conduit System . . . . . . . . . . . . . . . . . . . . . . . . 193
112 Galvanic Anode Cathodic Protection for Hydrant
Refueling System . . . . . . . . . . . . . . . . . . . . . . 197
113 Galvanic Anode Cathodic Protection System for
Steel Sheet Piling Bulkhead . . . . . . . . . . . . . . . . . 200
114 Impressed Current Cathodic Protection System
for Steel Sheet Piling Bulkhead . . . . . . . . . . . . . . . 207
115 Pier Supported by H Piling for Para. 9.12 . . . . . . . . . . 208
116 Test Station for Under-Road Casing Isolation . . . . . . . . 215
117 Vertical Sacrificial Anode Installation . . . . . . . . . . . 217
118 Horizontal Sacrificial Anode Installation When
Obstruction is Encountered . . . . . . . . . . . . . . . . 218
119 Horizontal Sacrificial Anode Installation -
Limited Right-of-Way . . . . . . . . . . . . . . . . . . . 218
120 Vertical HSCBCI Anode Installation . . . . . . . . . . . . . 220
121 Vertical HSCBCI Anode Installation With Packaged
Backfill . . . . . . . . . . . . . . . . . . . . . . . . . 221
122 Horizontal HSCBCI Anode Installation . . . . . . . . . . . . 222
123 Typical Deep Well Anode Cathodic Protection
Installation . . . . . . . . . . . . . . . . . . . . . . . 223
124 Deep Anode Installation Details . . . . . . . . . . . . . . . 224
125 Typical Pole-Mounted Cathodic Protection
Rectifier Installation . . . . . . . . . . . . . . . . . . 226
126 Typical Pad-Mounted Cathodic Protection
Rectifier Installation . . . . . . . . . . . . . . . . . . 227
127 Form for Recording and Reporting Monthly
Rectifier Readings . . . . . . . . . . . . . . . . . . . . . 233
128 Form for Recording and Reporting Quarterly
Structure-to-Electrode Potentials . . . . . . . . . . . . 234
TABLES
Table 1 Current Requirements for Cathodic Protection of
Bare Steel . . . . . . . . . . . . . . . . . . . . . . . . . 20
2 Current Requirements for Cathodic Protection of
Coated Steel . . . . . . . . . . . . . . . . . . . . . . . 21
3 Galvanic Anode Size Factors . . . . . . . . . . . . . . . . . 25
4 Structure Potential Factor . . . . . . . . . . . . . . . . . 26
5 Adjusting Factor for Multiple Anodes (F) . . . . . . . . . . 27
6 Corrections Factors - Short Line Coating Conductance . . . . 33
7 Results of Structure-to-Electrolyte
Potential Measurements . . . . . . . . . . . . . . . . . . 43
8 Standard HSCBCI Anodes . . . . . . . . . . . . . . . . . . . 80
9 Special HSCBCI Anodes . . . . . . . . . . . . . . . . . . . . 82
10 Standard Wire Characteristics . . . . . . . . . . . . . . . . 92
11 M Factors for Determining Economic Wire Size
(Cost of losses in 100 feet of copper cable
at 1 cent per kWhr) . . . . . . . . . . . . . . . . . . . . 95
12 Standard Alloy Magnesium Anodes - Standard
Sizes for Use in Soil . . . . . . . . . . . . . . . . . . . 120
13 Standard Alloy Magnesium Anodes - Standard
Sizes for Use in Water . . . . . . . . . . . . . . . . . . 121
14 Standard Alloy Magnesium Anodes -Standard
Sizes for Condensors and Heat Exchangers . . . . . . . . . 121
15 Standard Alloy Magnesium Anodes - Elongated . . . . . . . . . 122
16 High Potential Alloy Magnesium Anodes - Standard
Sizes for Soil and Water . . . . . . . . . . . . . . . . . 122
17 Standard Alloy Magnesium Anodes - Standard Size
Extruded Rod for Water Tanks and Water Heaters . . . . . . 123
18 Zinc Anodes - Standard Sizes for Underground or
Fresh Water . . . . . . . . . . . . . . . . . . . . . . . . 123
19 Zinc Anodes - Special Sizes for Underground or
Fresh Water . . . . . . . . . . . . . . . . . . . . . . . . 124
20 Zinc Anodes - Standard Sizes for Use in Seawater . . . . . . 124
21 Zinc Anodes - Special Sizes for Use in Seawater . . . . . . . 125
22 Aluminum Pier and Piling Anodes - Standard Sizes . . . . . . 128
23 Type I Aluminum Alloy Anodes - Standard Sizes
for Offshore Use . . . . . . . . . . . . . . . . . . . . . 129
24 Type III Aluminum Alloy Anodes for Offshore Use . . . . . . . 130
25 Aluminum Alloy Hull Anodes - Standard Sizes
(Types I, II, and III) . . . . . . . . . . . . . . . . . . 132
26 Aluminum Alloy Bracelet Anode - Standard Sizes . . . . . . . 133
27 Technical Data - Commonly Used HSCBCI Anodes . . . . . . . . 161
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
2 Corrosion Cell - Zinc and Platinum
in Hydrochloric Acid . . . . . . . . . . . . . . . . . . . 6
3 Cathodic Protection Cell . . . . . . . . . . . . . . . . . . 7
4 Hydraulic Analogy of Cathodic Protection . . . . . . . . . . 7
5 Sacrificial Anode Cathodic Protection/Impressed
Current Cathodic Protection . . . . . . . . . . . . . . . . 9
6 Structure-to Electrolyte Potential Measurement . . . . . . . 14
7 Failure Rate Versus Time . . . . . . . . . . . . . . . . . . 17
8 Temporary Cathodic Protection System for
Determining Current Requirements . . . . . . . . . . . . . 23
9 4-Pin Soil Resistivity Measurement . . . . . . . . . . . . . 30
10 Soil Box for Determination of Resistivity . . . . . . . . . . 30
11 pH Meter . . . . . . . . . . . . . . . . . . . . . . . . . . 32
12 Antimony Electrode Potential Versus pH . . . . . . . . . . . 32
13 Coating Conductance - Short Line Method . . . . . . . . . . . 34
14 Coating Conductance - Long Line Method . . . . . . . . . . . 34
15 Continuity Testing - Potential Method . . . . . . . . . . . . 36
16 Continuity Testing - Potential Drop Method . . . . . . . . . 36
17 Continuity Testing - Pipe Locator Method . . . . . . . . . . 37
18 Insulation Testing - Two-Wire Test Station . . . . . . . . . 37
19 Interference from Impressed Current
Cathodic Protection System . . . . . . . . . . . . . . . . 40
20 Interference Due to Potential Gradients . . . . . . . . . . . 41
21 Interference Testing . . . . . . . . . . . . . . . . . . . . 42
22 Plot of Potentials from Interference Test . . . . . . . . . . 42
23 Measurement of Current Flow in Structure . . . . . . . . . . 44
24 Correction of Interferencce - Direct Bonding . . . . . . . . 44
25 Correction of Interference - Resistive Bonding . . . . . . . 45
26 Effects of Bonding on Interference Test
Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
27 Bonding for Continuity . . . . . . . . . . . . . . . . . . . 48
28 Control of Interference - Sacrificial Anode . . . . . . . . . 48
29 Interference Due to Cathodic Protection of
Quaywall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
30 Correction of Interference - Bonding . . . . . . . . . . . . 51
31 Equavalent Cathodic Protection Circuit . . . . . . . . . . . 54
32 Single-Phase - Full-Wave Bridge Rectifier . . . . . . . . . . 62
33 Full-Wave Rectified Current . . . . . . . . . . . . . . . . . 64
34 Single-Phase - Center Tap Circuit . . . . . . . . . . . . . . 64
35 Three-Phase Bridge Circuit . . . . . . . . . . . . . . . . . 65
36 Three-Phase Wye Circuit . . . . . . . . . . . . . . . . . . . 66
37 Half-Wave Rectified Current . . . . . . . . . . . . . . . . . 66
38 Constant Current Rectifier . . . . . . . . . . . . . . . . . 67
39 Constant Potential Rectifier . . . . . . . . . . . . . . . . 67
40 Multicircuit Constant Current Rectifier . . . . . . . . . . . 68
41 Efficiency Versus Voltage - Selenium Stacks . . . . . . . . . 72
42 Efficiency Versus Voltage - Silicon Stacks . . . . . . . . . 73
43 Anode-to-Cable Connection - Graphite Anode . . . . . . . . . 75
44 Center Connected Graphite Anode . . . . . . . . . . . . . . . 76
45 Duct Anode . . . . . . . . . . . . . . . . . . . . . . . . . 83
46 Button Anode . . . . . . . . . . . . . . . . . . . . . . . . 83
47 Bridge Deck Anode - Type I . . . . . . . . . . . . . . . . . 84
48 Bridge Deck Anode - Type II . . . . . . . . . . . . . . . . . 85
49 Tubular Anode . . . . . . . . . . . . . . . . . . . . . . . . 86
50 Anode to Cable Connection - Epoxy Seal . . . . . . . . . . . 87
51 Anode to Cable Connection - Teflon Seal . . . . . . . . . . . 88
52 Center Connected High Silicon Chromium
Bearing Cast Iron Anode . . . . . . . . . . . . . . . . . . 89
53 Typical Platinized Anode . . . . . . . . . . . . . . . . . . 90
54 Flush-Mounted Potential Test Station . . . . . . . . . . . . 97
55 Soil Contact Test Station . . . . . . . . . . . . . . . . . . 98
56 IR Drop Test Station . . . . . . . . . . . . . . . . . . . . 99
57 Insulating Flange Test Station (Six-Wire) . . . . . . . . . . 100
58 Wiring for Casing Isolation Test Station . . . . . . . . . . 101
59 Bond Test Station . . . . . . . . . . . . . . . . . . . . . . 101
60 Anode Balancing Resistors . . . . . . . . . . . . . . . . . . 102
61 Bonding of a Dresser-Style Coupling . . . . . . . . . . . . . 103
62 Bonding Methods for Cast Iron Bell-and-Spigot
Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
63 Isolating a Protected Line from an Unprotected
Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
64 Electrical Bond . . . . . . . . . . . . . . . . . . . . . . . 106
65 Thermosetting-Resin Pipe Connection . . . . . . . . . . . . . 106
66 Clamp Type Bonding Joint . . . . . . . . . . . . . . . . . . 107
67 Underground Splice . . . . . . . . . . . . . . . . . . . . . 108
68 Welded Type Bonding Joint for Slip-On
Pipe Installed Aboveground . . . . . . . . . . . . . . . . 109
69 Test Box for an Insulating Fitting . . . . . . . . . . . . . 110
70 Steel Insulating Joint Details for Flanged
Pipe Installed Below Grade . . . . . . . . . . . . . . . . 111
71 Steel Insulating Joint Details for Aboveground
Flanged Pipe . . . . . . . . . . . . . . . . . . . . . . . 112
72 Insulating Joint Details for Screwed Pipe
Connections . . . . . . . . . . . . . . . . . . . . . . . . 112
73 Efficiency Versus Current Density - Magnesium
Anodes . . . . . . . . . . . . . . . . . . . . . . . . . . 118
74 Aluminum Alloy Bracelet Anodes . . . . . . . . . . . . . . . 133
75 Current-Potential Test Station . . . . . . . . . . . . . . . 135
76 Typical Building Underground Heat & Water Lines . . . . . . . 138
77 Impressed Current Point Type Cathodic Protection
for Aircraft Hydrant Refueling System . . . . . . . . . . . . 138
78 Galvanic Anode Type Cathodic Protection for
Coated Underground Sewage Lift Station . . . . . . . . . . . 139
79 Zinc Anode on Reinforced Concrete Block . . . . . . . . . . . 140
80 Radiant Heat or Snow-Melting Piping . . . . . . . . . . . . . 141
81 Cathodic Protection of Foundation Piles . . . . . . . . . . . 142
82 Impressed Current Cathodic Protection for
Existing On-Grade Storage Tank . . . . . . . . . . . . . . 142
83 Impressed Current Cathodic Protection with
Horizontal Anodes for On-Grade Storage Tank - New
Installation . . . . . . . . . . . . . . . . . . . . . . . 143
84 On-Grade Fresh Water Tank Using Suspended Anodes . . . . . . 144
85 Open Water Box Cooler . . . . . . . . . . . . . . . . . . . . 144
86 Horizontal Hot Water Tank - Magnesium Anode
Installation . . . . . . . . . . . . . . . . . . . . . . . 145
87 Impressed Current Cathodic Protection System for
Sheet Piling for Wharf Construction . . . . . . . . . . . . 146
88 Suspended Anode Cathodic Protection for H-Piling
in Seawater . . . . . . . . . . . . . . . . . . . . . . . . . 146
89 Cathodic Protection for H-Piling in Seawater . . . . . . . . 147
90 Cellular Earth Fill Pier Supports . . . . . . . . . . . . . . 148
91 Elevated Fresh Water Tank Using Suspended Anodes . . . . . . 149
92 Cathodic Protection of Tanks using Rigid
Floor-Mounted Anodes . . . . . . . . . . . . . . . . . . . 150
93 Cathodic Protection of Hydraulic Elevator
Cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . 151
94 Hydraulic Hoist Cylinder . . . . . . . . . . . . . . . . . . 152
95 Typical Cathodic Protection of Underground Tank
Farm . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
96 Gasoline Service Station System . . . . . . . . . . . . . . . 154
97 Segmented Elevated Tank for Area Calculations . . . . . . . . 157
98 Anode Spacing for Elevated Steel Water Tank . . . . . . . . . 160
99 Anode Suspension Arrangement for Elevated
Steel Water Tank . . . . . . . . . . . . . . . . . . . . . 162
100 Equivalent Diameter for Anodes in a
Circle in Water Tank . . . . . . . . . . . . . . . . . . . 163
101 Fringe Factor for Stub Anodes . . . . . . . . . . . . . . . . 164
102 Elevated Steel Water Tank Showing Rectifier and
Anode Arrangement . . . . . . . . . . . . . . . . . . . . . 172
103 Hand Hole and Anode Suspension Detail for
Elevated Water Tank . . . . . . . . . . . . . . . . . . . . . . . . . 174
104 Riser Anode Suspension Detail for Elevated Water
Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
105 Dimensions: Elevated Steel Water Tank . . . . . . . . . . . 175
106 Cathodic Protection for Tanks Using Rigid Mounted . . . . . . 178
Button-Type Anodes and Platinized Titanium Wire
107 Cathodic Protection System for Gas Main . . . . . . . . . . . 179
108 Layout of Gas Piping in Residential District . . . . . . . . 184
109 Cathodic Protection for Black Iron, Hot Water
Storage Tank . . . . . . . . . . . . . . . . . . . . . . . . 187
110 Galvanic Anode Cathodic Protection of
Underground Steel Storage Tank . . . . . . . . . . . . . . . 191
111 Impressed Current Cathodic Protection for
Heating Conduit System . . . . . . . . . . . . . . . . . . . . . . . . 193
112 Galvanic Anode Cathodic Protection for Hydrant
Refueling System . . . . . . . . . . . . . . . . . . . . . . 197
113 Galvanic Anode Cathodic Protection System for
Steel Sheet Piling Bulkhead . . . . . . . . . . . . . . . . . 200
114 Impressed Current Cathodic Protection System
for Steel Sheet Piling Bulkhead . . . . . . . . . . . . . . . 207
115 Pier Supported by H Piling for Para. 9.12 . . . . . . . . . . 208
116 Test Station for Under-Road Casing Isolation . . . . . . . . 215
117 Vertical Sacrificial Anode Installation . . . . . . . . . . . 217
118 Horizontal Sacrificial Anode Installation When
Obstruction is Encountered . . . . . . . . . . . . . . . . 218
119 Horizontal Sacrificial Anode Installation -
Limited Right-of-Way . . . . . . . . . . . . . . . . . . . 218
120 Vertical HSCBCI Anode Installation . . . . . . . . . . . . . 220
121 Vertical HSCBCI Anode Installation With Packaged
Backfill . . . . . . . . . . . . . . . . . . . . . . . . . 221
122 Horizontal HSCBCI Anode Installation . . . . . . . . . . . . 222
123 Typical Deep Well Anode Cathodic Protection
Installation . . . . . . . . . . . . . . . . . . . . . . . 223
124 Deep Anode Installation Details . . . . . . . . . . . . . . . 224
125 Typical Pole-Mounted Cathodic Protection
Rectifier Installation . . . . . . . . . . . . . . . . . . 226
126 Typical Pad-Mounted Cathodic Protection
Rectifier Installation . . . . . . . . . . . . . . . . . . 227
127 Form for Recording and Reporting Monthly
Rectifier Readings . . . . . . . . . . . . . . . . . . . . . 233
128 Form for Recording and Reporting Quarterly
Structure-to-Electrode Potentials . . . . . . . . . . . . 234
TABLES
Table 1 Current Requirements for Cathodic Protection of
Bare Steel . . . . . . . . . . . . . . . . . . . . . . . . . 20
2 Current Requirements for Cathodic Protection of
Coated Steel . . . . . . . . . . . . . . . . . . . . . . . 21
3 Galvanic Anode Size Factors . . . . . . . . . . . . . . . . . 25
4 Structure Potential Factor . . . . . . . . . . . . . . . . . 26
5 Adjusting Factor for Multiple Anodes (F) . . . . . . . . . . 27
6 Corrections Factors - Short Line Coating Conductance . . . . 33
7 Results of Structure-to-Electrolyte
Potential Measurements . . . . . . . . . . . . . . . . . . 43
8 Standard HSCBCI Anodes . . . . . . . . . . . . . . . . . . . 80
9 Special HSCBCI Anodes . . . . . . . . . . . . . . . . . . . . 82
10 Standard Wire Characteristics . . . . . . . . . . . . . . . . 92
11 M Factors for Determining Economic Wire Size
(Cost of losses in 100 feet of copper cable
at 1 cent per kWhr) . . . . . . . . . . . . . . . . . . . . 95
12 Standard Alloy Magnesium Anodes - Standard
Sizes for Use in Soil . . . . . . . . . . . . . . . . . . . 120
13 Standard Alloy Magnesium Anodes - Standard
Sizes for Use in Water . . . . . . . . . . . . . . . . . . 121
14 Standard Alloy Magnesium Anodes -Standard
Sizes for Condensors and Heat Exchangers . . . . . . . . . 121
15 Standard Alloy Magnesium Anodes - Elongated . . . . . . . . . 122
16 High Potential Alloy Magnesium Anodes - Standard
Sizes for Soil and Water . . . . . . . . . . . . . . . . . 122
17 Standard Alloy Magnesium Anodes - Standard Size
Extruded Rod for Water Tanks and Water Heaters . . . . . . 123
18 Zinc Anodes - Standard Sizes for Underground or
Fresh Water . . . . . . . . . . . . . . . . . . . . . . . . 123
19 Zinc Anodes - Special Sizes for Underground or
Fresh Water . . . . . . . . . . . . . . . . . . . . . . . . 124
20 Zinc Anodes - Standard Sizes for Use in Seawater . . . . . . 124
21 Zinc Anodes - Special Sizes for Use in Seawater . . . . . . . 125
22 Aluminum Pier and Piling Anodes - Standard Sizes . . . . . . 128
23 Type I Aluminum Alloy Anodes - Standard Sizes
for Offshore Use . . . . . . . . . . . . . . . . . . . . . 129
24 Type III Aluminum Alloy Anodes for Offshore Use . . . . . . . 130
25 Aluminum Alloy Hull Anodes - Standard Sizes
(Types I, II, and III) . . . . . . . . . . . . . . . . . . 132
26 Aluminum Alloy Bracelet Anode - Standard Sizes . . . . . . . 133
27 Technical Data - Commonly Used HSCBCI Anodes . . . . . . . . 161
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
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