Cathodic corrosion protection systems: a guide for oil and gas industries

Machine generated contents note: 1.1. Behavior of Buried or Immersed Metals in the Absence of CP

1.1.1. The Nature of Metallic Corrosion

1.1.2. Polarization

1.1.3. Formation of Cells

1.1.4. Passivity

1.1.5. Reactions at Cathodic Areas

1.2. Cathodic Protection

1.2.1. Basis of CP

1.3. Considerations Applicable to Most Types of Structures

1.3.1. Range of Application

1.3.2. Basis of Design

1.3.3. Design or Modification of Structures to be Protected

1.3.4.Comparison of the Various Systems

1.3.5. Special Considerations

1.3.6. Measures to Safeguard Neighboring Structures

1.3.7. Design of CP Installations to Minimize Corrosion Interaction

1.3.8. Measures to Reduce Corrosion Interaction

1.3.9. CP Systems Installed Adjacent to Telecommunication Services

1.3.10. CP Systems Adjacent to Railway Signals and Protection Circuits

1.3.11. Interaction at Discontinuities in Cathodically Protected Structures

1.3.12. Jetties and Ships: Corrosion Interaction at Sea and River Terminals

1.4. Safety Aspects

1.4.1. Danger of Electric Shock

1.4.2. Fault Conditions in Electricity Power Systems in Relation to Remedial and/or Unintentional Bonds

1.4.3. Hydrogen Evolution

1.4.4. Installation in Hazardous Atmospheres

2.1. Criteria for Cathodic Protection

2.2. Buried Pipes

2.3. Tanks Exteriors

2.4. Submerged Pipelines

2.5. Offshore Structures and Ship Hulls

2.6. Tank, Pipe, and Water Box Interiors

2.7. Well Casings

2.8. Types of Cathodic Protection Systems

2.8.1. Impressed Current Systems

2.8.2. Galvanic Anode Systems

2.8.3. Galvanic versus Impressed Current System

2.9. Equipment and Facilities for Impressed Current Systems

2.9.1. Cathodic Protection Transformer Rectifiers

2.9.2. Alternative Cathodic Protection Power Sources

2.9.3. Impressed Current Anodes

2.9.4. Cables

2.9.5. Insulating Devices

2.9.6. Anode Beds

2.9.7. Electrical Bonding Station

2.9.8. Test Stations

2.9.9. Connections

2.9.10. Electrical Continuity

2.9.11. Protective Coatings

2.9.12. Insulation

2.9.13. Safety

2.9.14. Site Survey

2.9.15. Provision for Testing

2.10. Cathodic Protection of Buried Steel Pipes

2.10.1. Application

2.10.2. Types of Cathodic Protection Systems

2.10.3. Galvanic Anode Systems

2.10.4. Isolation of Buried Pipes

2.10.5. Test and Bonding Stations

2.10.6. Cased Crossing Test Station

2.10.7. Line Crossing Test Station

2.10.8. Insulated Fitting Test Station

2.10.9. System Design

2.10.10. Particular Considerations

2.11. Cathodic Protection In-Plant Facilities

2.11.1. Application

2.11.2. Types of Cathodic Protection Systems

2.11.3. Impressed Current System Details

2.11.4. Galvanic Anode System Details

2.11.5. Test and Bonding Stations

2.11.6. Hazardous Locations

2.11.7. Oil Storage Tank Bottoms

2.12. Cathodic Protection of Vessel and Tank Internals

2.12.1. Types of Cathodic Protection Systems

2.12.2. Current Density

2.12.3. Anode Distribution

2.12.4. Reference Electrode Position

2.12.5. Protection of Specific Installations

2.13. Cathodic Protection of Marine Structures

2.13.1. Current Density

2.13.2. Marine Structural Zones

2.13.3. Zone Protection

2.13.4. Protection of Specific Installations Including Vessels

2.13.5. Anodes for Impressed Current Systems

2.13.6. Anodes for Galvanic Anode Systems

2.13.7. Boosted Polarization

2.13.8. Cathodic Protection Design for Marine Structures

2.13.9. Fixed Potential Monitoring Systems

2.13.10. Potential Survey

2.13.11. Retrofits

2.14. Anodic Protection

2.14.1. Principles of Anodic Protection

2.14.2. Contrast with Cathodic Protection

2.14.3. Effects of Variable Factors on Anodic Protection

2.14.4. Applications to Process Plants

3.1. Principles of Cathodic Protection

3.2. Methods of Applying Cathodic Protection

3.2.1. Impressed Current

3.2.2. Sacrificial Anodes

3.3. Protection Potentials

3.4. Current Density

3.5. Coatings

3.6. Calcareous Scales

3.7. Choice of a Cathodic-Protection System

3.8. Anode Resistance

3.9. Impressed-Current System

3.9.1. Current[

]Voltage Relationships

3.9.2. Single Drain Point

3.9.3. Multiple Drain Points

3.9.4. Effect of Coating

3.9.5. Point of Minimum Protection

3.9.6. Bare and Poorly Coated Lines

3.9.7. Voltage Limitations

3.9.8. Current Requirements

3.9.9. Measurements

3.9.10. Sizing of Rectifiers

3.9.11. Calculations

3.10. Galvanic Anode System

3.10.1. Symbols

3.10.2. Current Output

3.11. Design Principle of Cathodic Protection for Marine Structures

3.11.1. Design- Calculations

3.11.2. Single Cylindrical Vertical Anode

3.11.3. Group of Vertical Anodes Equally Spaced in a Straight Line

3.11.4. Galvanic Anode Systems

3.11.5. Anode Output Formula

3.11.6. Pipelines and Attenuation of Potential

3.11.7. Sacrificial Anode Materials

3.11.8. The Use of Sacrificial.

Anodes for Internal Cathodic Protection

3.11.9. The Type and Number of Anodes Required

3.11.10. Anode Location

3.11.11. The Use of Sacrificial Anodes for External Cathodic Protection

3.11.12. The Type and Number of Anodes Required (Full Hull Protection)

3.12. Anode Location

3.12.1. Fitting Out Protection

3.12.2. Tank Descaling

3.12.3. Individual Anode Output Determination and Calculation (Sacrificial Anodes)

3.12.4. Impressed Current

3.13. Anodic Protection

4.1. Impressed Current Anodes

4.2. Manufacturing of Materials

4.3. Anode Casting

4.3.1. Casting of High-Silicon[

]Chromium[

]Iron Anode

4.3.2. Casting of Graphite Anode

4.3.3. Casting of Magnetite Anode

4.4. Lead Wire-to-Anode Connection

4.5. Anode Lead Wire

4.5.1. Conductor

4.5.2. Lead Wire Insulation

4.6. Properties

4.6.1. Mechanical Resistance Test

4.6.2. Electrical Resistance Test

4.6.3. Temperature Dependence

4.6.4. Fluoropolymer-Insulated Anode Lead Wire Test

4.6.5. Radiographic Test

4.7. Dimensions and Weights

4.8. Carbonaceous Backfill for Impressed Current Anodes

4.8.1. Requirements

4.8.2. Bulk Density

4.8.3. Resistivity

4.8.4. Particle Size

4.9. Galvanic Anodes for Underground Applications (Magnesium and Zinc)

4.9.1. Classification

4.9.2. Materials and Manufacture

4.9.3. Anode Composition

4.9.4. Anode Core

4.9.5. Production Testing

4.9.6. Requirements

4.9.7. Workmanship, Finish, and Appearance

4.9.8. Mechanical Resistance

4.9.9. Electrical Resistance

4.9.10. Anode Dimensions and Weights

4.9.11. Zinc Anodes

4.9.12. Methods of Attachment of Cable for Cast Anodes

4.9.13. Identification of Anodes

4.10. Chemical Backfill for Galvanic Anodes

4.10.1. Backfill Composition

4.10.2. Particle Size

4.10.3. Backfill Analysis

4.10.4. Anode Packaging

4.11. Method for the Determination of the Anode-to-Core Resistance of Galvanic Anodes

4.11.1. Circuit

4.11.2. Procedure

4.12. Galvanic Anodes for Submerged Applications (Magnesium and Zinc)

4.12.1. Materials and Manufacture

4.12.2. Magnesium Anodes

4.12.3. Zinc Anodes

4.12.4. Production Testing

4.12.5. Requirements

4.12.6. Quality of Steel Inserts

4.12.7. Electrical Resistance

4.12.8. Identification of Anodes

4.13. Method for the Determination of the Anode-to-Core Resistance of Galvanic Anodes

4.13.1. Principle

4.13.2. Apparatus

4.13.3. Circuit

4.13.4. Procedure

4.14. Bracelet-Type Galvanic Anodes for Submarine Pipelines (Aluminum and Zinc)

4.14.1. Materials and Manufacture

4.14.2. Alloy Composition

4.14.3. Production Testing

4.15. Anode Core Steel Works

4.15.1. Insert Material

4.15.2. Insert Surface Preparation

4.15.3. Welding

4.15.4. Requirements

4.15.5. Mechanical Resistance

4.15.6. Electrical Resistance

4.15.7. Consumption Rate of Aluminum Anodes in Seawater

4.15.8. Closed Circuit Potential of Aluminum Anodes in Seawater

4.15.9. Surface Irregularities in the Anode Casting

4.15.10. Cracks in Cast Anodes Material

4.15.11. Anode Connections

4.16. Method for the Determination of the Anode-to-Core Resistance of Galvanic Anodes

4.16.1. Apparatus

4.16.2. Circuit

4.16.3. Procedure

4.17. Method for the Determination of the Consumption Rate of Aluminum Anode Alloys Immersed in Seawater

4.17.1. Apparatus

4.17.2. Circuit

4.17.3. Preparation of Test Anodes

4.17.4. Procedure

4.18. Method for the Determination of the Closed-Circuit Potential of Aluminum Anodes Immersed in Seawater

4.18.1. Apparatus

4.18.2. Circuit

4.18.3. Preparation of Test Anode

4.18.4. Procedure

4.19. Cast Galvanic Anodes for Fixed Offshore Installations (Aluminum)

4.19.1. Materials and Manufacture

4.19.2. Type of Anodes

4.19.3. Chemical Composition

4.19.4. Production Testing

4.19.5. Anode Insert

4.20. Requirements

4.20.1. Casting Quality

4.20.2. Weight and Dimensional Tolerances

4.20.3. Performance Requirements

4.20.4. Identification of Anodes

4.20.5. Anode Protection

4.21. CP Cables

4.21.1. Conductor

4.21.2. Insulation

4.21.3. Insulating Materials

4.22. Specific Cable Requirements

4.22.1. Positive Conductor Cable

4.22.2. Negative, Bond, or Test Conductor Cable

4.23. Quality Assurance Provisions

4.24. Tests

4.25. Fabrication and Inspection of Monolithic Insulating Joints

4.25.1. Design

4.25.2. Materials

4.25.3. Manufacture

4.26. Approved Welding Processes

4.27. Coating

4.28. Quality Assurance Provisions

4.29. Tests

4.29.1. Chemical Analysis

4.29.2. Mechanical Test

4.29.3. Dielectric Test and Megger Test

4.29.4. Hydrostatic Test

4.29.5. Low Pressure Leakage Test (Air Test)

4.29.6. Prototype Tests

4.29.7. Radiographic Test

4.29.8. Magnetic Particle and Ultrasonic Test

4.29.9. Dye Penetrant Test

4.29.10. Visual Inspection and Dimensional Check

4.30. Flange Insulation Kit

4.30.1. Materials

4.30.2. Requirements

4.30.3. Detail Requirements for Insulating Gaskets and Sleeves

4.30.4. Packaging

4.30.5. Quality Assurance Provisions

Note continued: 4.30.6. Sampling

4.31. Polypropylene Rope

4.31.1. Requirements

4.31.2. Other Characteristics

4.31.3. Quality Assurance Provisions

4.31.4. Splicing Kit

4.31.5. Description

4.31.6. Materials and Manufacture

4.31.7. Properties of Catalyzed Resins

4.31.8. Packaging

4.31.9. Sampling

4.32. Split Bolt Connector (Line Tap)

4.32.1. Materials and Manufacture

4.32.2. Dimensions

4.32.3. Workmanship, Finish, and Appearance

4.32.4. Quality Assurance Provisions

4.32.5. Splice Coating Materials

4.32.6. Electrical Insulating Plastic Tape

4.33. Rubber Splicing Tape

4.33.1. Materials and Manufacture

4.33.2. Requirements

4.33.3. Storage Test

4.33.4. Roll Size

4.33.5. Color

4.33.6. Packaging, and Sampling

4.34. Thermit Weld (Cad Weld) Powder

4.34.1. Sampling

5.1. Criteria for Cathodic Protection

5.1.1. Buried Pipes

5.1.2. Tanks Exteriors

5.1.3. Submerged Pipelines

5.1.4. Offshore Structures and Ship Hulls

5.1.5. Tank, Pipe, and Water Box Interiors

5.1.6. Well Casings

5.1.7. Potential Limits

5.1.8. Aluminum

5.1.9. Lead

5.1.10. Stainless Steels

5.1.11. Steel in Concrete

5.2. Periodic Inspection

5.2.1. Potential Survey

5.2.2. Test Equipment for Potential Survey

5.2.3. Procedure to Be Observed

5.3. Potential Survey of Buried Steel Pipes

5.3.1. Instruments

5.3.2. Potential Measurements

5.3.3.Compensation for the IR Drop Component in Cathodically Protected Pipelines

5.3.4. Overprotection

5.3.5. Potential Survey at Cased Crossings

5.3.6. Potential Tests at Insulating Devices

5.4. Potential Survey of Cathodically Protected Reinforced Concrete

5.4.1. Potential Measurement

5.4.2. Electrodes and Probes for Some Concretes

5.5. Potential Survey of Offshore Structures

5.5.1. Reference Electrodes

5.5.2. Methods of Measurement

5.5.3. Potential Measurements with a Diver-Operated Unit

5.5.4. Potential Measurements with Surface Voltmeter, Cable, and Measuring Electrode

5.5.5. Subsea Pipeline Potential Survey

5.5.6. Time Intervals

5.5.7. The Extent of the Potential Survey

5.6. Inspection of Rectifiers

5.6.1. Records

5.6.2. Major Points for Routing Inspection

5.6.3. Annual Inspection

5.7. Inspection of Ground Bed

5.7.1. On-land Ground Bed

5.7.2. Submerged Ground Beds

5.8. Inspection of Offshore Sacrificial Anodes

5.9. Current Survey

5.9.1. Pipelines

5.9.2. Offshore Structures

5.10. Inspection Following Failure Report

5.10.1. Increase in Circuit Resistance

5.10.2. Stray Electric Currents

5.10.3. Tests for Electrical Continuity

5.10.4. Problems Associated with Galvanic Anode Installation

5.11. Inspection and Survey for Efficiencies of Coatings

5.11.1. Coating Resistance Measurement

5.11.2. Attenuation Test Method

5.11.3. Pearson Method

5.11.4. Coating Inspection by C-Scan

5.11.5. Visual Inspection

5.11.6. Over-the-Line Potential Survey

5.12. Data Recording and Analysis

5.12.1. Data Recording

5.12.2. Analysis of Data

5.13. Interferences

5.13.1. Cathode Field Interferences

5.13.2. Measurements of Cathode Field Interferences

5.13.3. Anode Field Interferences

5.13.4. Measurements of Anode Field Interferences

5.13.5. Corrective Measurers

5.14. Meters and Equipment

5.14.1. Reference Electrode

5.14.2.C6pper/Copper Sulfate Electrode

5.14.3. Silver/Silver Chloride Electrode

5.14.4. Pure Zinc Electrode

5.14.5. Calomel Electrode

5.15. Potentiometer and Voltmeter

5.15.1. Conventional Voltmeter (High Resistance)

5.15.2. Potentiometer[

]Voltmeter

5.15.3. Potentiometer

6.1. Test Methods for the Short Circuit Point

6.1.1. Locating Casing Short Circuit

6.1.2. Insulation Tests

6.2. American Society for Testing and Material Standard Test Method for Half-Cell Potentials of Uncoated Reinforcing Steel Bar in Concrete

6.2.1. Scope

6.2.2. Significance and Use

6.2.3. Apparatus

6.2.4. Calibration Standardization

6.2.5. Procedure

6.2.6. Recording Half-Cell Potential Values

6.2.7. Data Presentation

6.2.8. Interpretation of Results

6.2.9. Report

6.2.10. Precision and Bias

6.3. Subsea Pipeline CP Survey Method

6.3.1. Introduction

6.3.2. System Components

6.3.3. Survey Operation

6.3.4. Survey Results

6.4. Line Current Survey Test Method

6.4.1. Test Procedure with the Test Point Consisting of Four Wires

6.4.2. Test Procedure Using the Null Amp Test Circuit for Line Current Measurement

6.5.Computer Modeling of Offshore CP Systems Utilized in CP Monitoring

6.5.1.Computerized Modeling Techniques

6.5.2. Short Theoretical Background

6.5.3. Numerical Solutions

6.5.4. Analysis of Existing CP Systems

6.5.5. Performance of Sacrificial Anodes

6.5.6. Analysis of Attenuation Curves at Sacrificial Anodes

6.5.7. Potentials in Nodal Areas[

]Improved Efficiency in Potential Surveys of Nodes

6.6. Coating Resistance Measurement Method

6.6.1. Current[

]Voltage Change Method

6.6.2. Pipeline Current with Interrupter On and Off

6.7. Test Method and Calculation for "Attenuation Constant"

6.7.1. Significance of Attenuation Constant

6.7.2. Example Use of Graph Relating to Attenuation Constant

6.8. Coating Inspection by the Pearson Method

6.8.1. Equipment

6.8.2. Procedure

6.8.3. Data Obtained

6.8.4. Presentation of Data

6.9. Coating Inspection by the C-Scan System

6.9.1.C-Scan System Features

6.9.2. Performing Survey by C-Scan

6.9.3. Advantages of the System

6.9.4. Theoretical Background

6.9.5. Operation Principle

6.10. Coating Evaluation by Electromagnetic Current Attenuation Survey

6.10.1. Equipment

6.10.2. Procedure

6.10.3. Data Obtained

6.10.4. Presentation of Data

6.10.5. Criteria and Interpretation

6.11. Close Interval Pipe-to-Soil Potential Survey

6.11.1. Measurement Intervals

6.11.2. Switching Frequency

6.11.3. Distance Measurement

6.11.4. Stationary Measurements

6.11.5. Equipment

6.11.6. Procedure

6.11.7. Data Obtained

6.11.8. Presentation of Data

6.11.9. Criteria and Interpretation

6.12. An Example for Cathodic Field Interference Test Method

6.13. Tests for Electrical Continuity

7.1. Galvanic Anodes

7.2. Impressed Current Anodes

7.3. Transformer/Rectifier Equipment

7.4. Excavation and Backfilling

7.5. Installation of CP Systems for Buried Pipelines

7.5.1. Installation of Impressed Current Systems

7.5.2. Installation of Transformer/Rectifier Equipment

7.5.3. Cabling

7.5.4. Electrical Connections

7.5.5. Installation of Test Stations (Test Points)

7.5.6. Installation of Test Box(es)

7.5.7. Earthing of CP Equipment

7.5.8. Fencing

7.5.9. Parallel Power Lines

7.5.10. Lightning Protection

7.5.11. Surge Arrestors

7.6. Installation of Galvanic Anode Systems

7.6.1. Single Packaged Anode

7.6.2. Multiple Galvanic Anodes

7.6.3. Extruded Ribbon Anodes

7.6.4. Connection of Galvanic Anodes to the Pipeline

7.7. Installation of CP Systems for Compact Buried Structures

7.7.1. Structure Preparation (to be- Considered by the Structural Constructor)

7.7.2. Installation of Permanent Reference Electrodes

7.7.3. Installation of Insulating Flanges, Joints, and Couplings

7.8. Installation of CP Systems for Internal Surfaces

7.8.1. Materials and Equipment Acceptance (or Compliance)

7.8.2. Installation of Impressed Current Systems

7.8.3. Safety Precautions

7.8.4. Installation of Galvanic Anode Systems

7.8.5. Permanently Installed Reference Electrodes

7.9. Installation of CP Systems for Marine Structures

7.9.1. Immersed Structures

7.9.2. Installation of Galvanic Anode Systems

7.9.3. Electrical Connections

7.9.4. Corrosion Control Test Stations, Connection, and Bonds

7.9.5. Installation of Insulating Joints/Flanges and Devices

7.10. Submarine Pipelines

7.10.1. Installation of Impressed Current Systems

7.10.2. Installation of Galvanic Anode Systems

7.10.3. Corrosion Control Test Stations, Connections, and Bonds

7.10.4. Reinforcement

7.10.5. Pipeline Crossings

7.11. Electrical Measurements and Tests

7.11.1. Potential Measurements

7.11.2. Potential Survey of Internal Protection of the Plant

7.11.3. Determination of Bond Resistance

7.12. Tests Prior to Installation of CP on Buried or Immersed Structures

7.12.1. Soil/Water Evaluation

7.12.2. Structure/Electrolyte "Natural" Potential Survey

7.12.3. Stray Electric Currents

7.12.4. Tests for Electrical Continuity

7.13. Tests during the Commissioning Period

7.13.1. Buried Structures

7.13.2. Fixed Immersed Structures

7.13.3. Internal Protection of Plant

7.13.4. Internal Surfaces

7.14. Specialized Surveys

8.1. Precommissioning Inspection and Check

8.2. Hookup and Commissioning

8.2.1. Impressed Current Systems

8.2.2. Sacrificial Anodes

8.2.3. Interference

8.3.Commissioning Survey

8.4.Commissioning Report

8.5. Installation of Electrical Isolation Equipment

8.5.1. Installation

8.5.2. Insulating Joints

8.5.3. Isolated Flange Joints

8.5.4. Protection Against External Moisture Ingress

8.5.5. Pipeline Casing Insulators

8.5.6. High Voltage Protection

8.6. Thermit Welding of CP Leads

8.7. Pipe Preparation

8.8. Thermit Weld Preparation and Procedure

8.9. Control of Interference Currents on Foreign Structures

8.10. Notifying Owners of Other Structures for Interference Testing

8.11. Interference Testing

8.11.1. Stage at Which Interference Tests Shall Be Made

8.11.2. Tests to Assess Interference.

8.11.3. Tests After Remedial Measures Have Been Applied

8.12. Criteria for Limiting Corrosion Interaction

8.12.1. Limit of Positive Structure/Electrolyte Potential Changes for All Structures

8.12.2. Negative Changes of Structure/Electrolyte Potential

8.12.3. Control of Interference

8.12.4. Control by the Use of Galvanic Anodes

8.12.5. Control by the Use of Impressed Current CP

8.12.6. Control by Bonding

Note continued: 8.12.7. Fault Conditions in Electricity Power Systems in Relation to Remedial and/or Unintentional Bonds

8.13. Telluric Current

8.14. AC Effects

8.15. Measurement of Soil Resistivity

8.16. Field Procedures

8.17. Frequency of Measurement

8.17.1. Presentation of Results

8.17.2. Criteria and Interpretation

8.18. Measurement of Electrode Resistance

8.18.1. Measurement of Earth Electrode Resistance

8.18.2. Measurement of Resistance of Earthing Conductor

8.19. Current Drainage Survey

8.19.1. Method

8.20. Determination In situ of the Redox Potential of Soil

8.20.1. Apparatus

8.20.2. Materials

8.20.3. Procedure

8.20.4. Calculations and Expression of the Results

8.20.5. Test Report

8.21. Inspection of CP Installations

8.21.1. CP Installations

8.21.2. Test Points, Cased Crossings and Insulating Joints

8.21.3. Coating Inspection

8.22. Installation in Hazardous Atmospheres

8.22.1. Bonds

8.22.2. Isolating Joints

8.22.3. Short Circuits between Points of Different Potentials

8.22.4. Disconnection, Separation, or Breaking of Protected Pipework

8.22.5. Electrical Equipment

8.22.6. Test Instruments

8.22.7. Internal Anodes

8.22.8. Sacrificial Anodes

8.22.9. Instruction of Personnel.