Anodic Protection: Theory and Practice in the Prevention of Corrosion

1 Anodic Protection of Metals-A Technique Whose Time Has Come.- Many Protective Methods Are Used.- Anodic Protection Used Effectively.- Protection of Alloy Steel Important.- Strategic and Absolute Factors Bearing on Materials.- Substitute Alloys for Chromium.- Prices of Substitute Alloys Increase.- Corrosion Protection Is Necessary.- Contamination Control Important.- Ecological Considerations Are Important.- Energy-Conservation Values.- Applications and Limitations.- Limitations Can Be Anticipated.- Installation Expense Factors.- Rapid Development Anticipated.- References.- 2 Anodic Protection of Industrial Equipment.- Sulfuric Acid Applications.- Sulfuric Acid Corrosion.- Hydrogen Attack Is Also a Problem.- Product Purity Is Important.- Protection of Sulfuric Acid Storage Equipment.- Application Details in Storage Tanks.- Spent Sulfuric Acid.- Heat Exchangers for Sulfuric Acid.- Transport of Sulfuric Acid.- Protection Provided for Barge.- Nitrate Fertilizer Container Protection.- Other Interesting Uses for Fertilizer Solutions.- Pulp and Paper Industry Applications.- Miscellaneous Applications.- Summary.- References.- 3 Equipment for Anodic Protection.- Characteristics of Electrodes.- Characteristics of the Cathode.- Platinum-Clad Cathodes.- Hastelloy C Cathodes.- Stainless (Cr-Ni) Steel Cathodes.- Reference-Electrode Designs.- Calomel Half-Cell.- Silver/Silver Chloride Half-Cell.- Mercury/Mercury Sulfate Half-Cell.- Metal Oxide Electrodes.- Metals As Reference Electrodes.- Electronic Control and Power Supplies.- Potential Controller.- Power Supplies.- Summary.- References.- 4 Design, Operation, and Maintenance of Anodic Protection Systems.- Design Requirements.- Electrochemistry.- Establishing Electrochemical Parameters.- Time Effects on Passivation Currents.- Electrodes.- Electronic-Hardware Selection.- Power-Supply Criteria.- Installation and Start-up.- Electrode-Installation Modes.- Electrical-Wiring Criteria.- Location of Power Supply and Controller.- Start-up Procedures.- Operation and Maintenance Parameters.- Corrosion-Rate Measurements.- How to Take Solution Samples.- Commercial Units Reliable.- Summary.- References.- 5 Economic Evaluation of Anodic Protection.- Known Costs of Anodic Protection.- Costs of Small Tanks.- Data on Larger Tanks.- Current Costs of Protecting Steel Tanks Against Sulfuric Acid.- Why Tanks Require Protection.- Cost of Internally Lining Tanks.- Sulfuric Acid Coolers.- Summary.- References.- 6 Principles of Anodic Protection.- Electrochemical Description of Passivity.- Characteristics of Anodic-Polarization Curves.- The Passive Metal Layer.- Proposed Mechanism of Iron Passivity.- Metal Passivity Breakdown.- References.- 7 The Potentiostat.- Potentiostat Mode.- Development of the Potentiostat.- Potential Control.- Control Amplifier.- Current Regulator.- Solid-State Potentiostats.- Commercial Electronic Potentiostats.- Portable/Field Potentiostat.- Summary Comments on Potentiostatic Mode.- The Potentiostat.- References.- 8 Laboratory Tests and Procedures.- Wiring Sequence for Potentiostatic Experiments.- Reproducibility of Potentiostatic and Potentiodynamic Anodic-Polarization Measurements.- Polarization Cells.- Elevated-Pressure Polarization Cells.- Proposed Experimental Procedure.- Experimental Procedure.- High-Temperature Polarization Cells.- Crevice Corrosion Testing Polarization Cells.- Summary.- References.- 9 Selected Examples of Anodic Protection.- Alloy Evaluation.- Alloy Effects.- Concentration Effects.- Temperature Effects.- Environmental Effects.- Preliminary Investigations Are Necessary.- Time Effects.- References.- 10 Future Uses for Anodic Protection.- A Realm of Probability.- Cooling-Tower Water.- Raney Catalyst.- Prosthetic Implants.- Stainless Steel Pickling.- Molten Salt-Metal Technology.- Metallography.- Coolant Systems.- Solution-Potential Concept.- Sulfide Minerals.- Enzyme Production.- Surface-Area-Ratio Concept.- The Sufficiently Real Possibilities.- Potentiostatic Cond