Electrical Engineering Cathodic Protection

Section 1 INTRODUCTION 1.1 Scope. 1.2 Cancellation. 1.3 Related Technical Documents. Section 2 CATHODIC PROTECTION CONCEPTS 2.1 Corrosion as an Electrochemical Process. 2.2 The Electrochemical Basis for Cathodic Protection. 2.3 Practical Application of Cathodic Protection. 2.3.1 When Cathodic Protection Should Be Considered. 2.3.2 Functional Requirements for Cathodic Protection 2.4 Sacrificial Anode Systems. 2.4.1 Anode Materials. 2.4.2 Connection to Structure. 2.4.3 Other Requirements. 2.5 Impressed Current Systems. Section 3 CRITERIA FOR CATHODIC PROTECTION 3.1 Introduction. 3.2 Electrical Criteria. 3.3 Interpretation of Structure-to-Electrolyte Potential Readings. 3.4 Failure Rate Analysis. 3.5 Nondestructive Testing of Facility. 3.6 Consequences of Underprotection. 3.7 Consequences of Overprotection. 3.7.1 Coating Disbondment. 3.7.2 Hydrogen Embrittlement. Section 4 CATHODIC PROTECTION SYSTEM DESIGN PRINCIPLES 4.1 Introduction. 4.2 General Design Procedures. 4.3 Determination of Field Data. 4.3.1 Determination of Electrolyte Resistivity 4.3.2 Chemical Analysis of the Environment 4.3.3 Coating Conductance. 4.3.4 Continuity Testing. 4.3.5 Insulation Testing. 4.4 Corrosion Survey Checklist. Section 5 PRECAUTIONS FOR CATHODIC PROTECTION SYSTEM DESIGN 5.1 Introduction. 5.2 Excessive Currents and Voltages. 5.2.1 Interference. 5.2.2 Effects of High Current Density. 5.2.3 Effects of Electrolyte pH. 5.3 Hazards Associated with Cathodic Protection. 5.3.1 Explosive Hazards. 5.3.2 Bonding for Electrical Safety. 5.3.3 Induced Alternating Currents. Section 6 IMPRESSED CURRENT SYSTEM 6.1 Advantages of Impressed Current Cathodic Protection Systems. 6.2 Determination of Circuit Resistance. 6.2.1 Anode-to-Electrolyte Resistance. 6.2.2 Structure-to-Electrolyte Resistance. 6.2.3 Connecting Cable Resistance. 6.2.4 Resistance of Connections and Splices. 6.3 Determination of Power Supply Requirements. 6.4 Selection of Power Supply Type. 6.5 Rectifier Selection. 6.6 Anodes for Impressed Current Systems. 6.7 Other System Components. 6.7.1 Connecting Cables. 6.7.2 Wire Splices and Connections. 6.7.3 Test Stations. 6.7.4 Bonds. 6.7.5 Insulating Joints. Section 7 SACRIFICIAL ANODE SYSTEM DESIGN 7.1 Theory of Operation. 7.2 Sacrificial Anode Cathodic Protection System Design Procedures. 7.3 Determination of Current Required for Protection. 7.4 Determination of Anode Output. 7.5 Determination of Number of Anodes Required. 7.6 Determination of Anode Life. 7.7 Seasonal Variation in Anode Output. 7.8 Sacrificial Anode Materials 7.9 Other System Components Section 8 TYPICAL CATHODIC PROTECTION 8.1 Diagrams of Cathodic Protection Systems. Section 9 CATHODIC PROTECTION SYSTEM DESIGN EXAMPLES 9.1 Introduction. 9.2 Elevated Steel Water Tank. 9.3 Elevated Water Tank (Where Ice is Expected). 9.4 Steel Gas Main. 9.5 Gas Distribution System. 9.6 Black Iron, Hot Water Storage Tank. 9.7 Underground Steel Storage Tank. 9.8 Heating Distribution System. 9.9 Aircraft Multiple Hydrant Refueling System. 9.10 Steel Sheet Piling in Seawater (Galvanic nodes). 9.11 Steel Sheet Piling in Seawater (Impressed Current 9.12 Steel H Piling in Seawater (Galvanic Anodes). 9.13 Steel H Piling in Seawater (Impressed Current). Section 10 INSTALLATION AND CONSTRUCTION PRACTICES 10.1 Factors to Consider. 10.2 Planning of Construction. 10.3 Pipeline Coating. 10.4 Coatings for Other Structures. 10.5 Pipeline Installation. 10.6 Electrical Connections. 10.7 Test Stations. 10.8 Sacrificial Anode Installation. 10.9 Impressed Current Anode Installation. 10.10 Impressed Current Rectifier Installation. Section 11 SYSTEM CHECKOUT AND INITIAL ADJUSTMENTS 11.1 Introduction. 11.2 Initial Potential Survey. 11.3 Detection and Correction of Interference. 11.4 Adjustment of Impressed Current Systems. 11.5 Adjustment of Sacrificial Anode Systems. Section 12 MAINTAINING CATHODIC PROTECTION 12.1 Introduction. 12.2 Required Periodic Monitoring and Maintenance. 12.3 Design Data Required for System Maintenance. 12.4 Basic Maintenance Requirements. 12.5 Guidance for Maintenance Section 13 ECONOMIC ANALYSIS 13.1 Importance of Economic Analysis. 13.2 Economic Analysis Process. 13.3 Design of Cathodic Protection Systems. 13.4 Economic Analysis - Example 1 Section 14 CORROSION COORDINATING COMMITTEE PARTICIPATION