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Basic Electricity 1:6

CP 1 – Cathodic Protection Tester Course Manual

© NACE International, 2000

02/01/05

Electrical Schematic Diagram

Symbols

Resistor

Ground

Battery

Connection

Rectifier

Switch

Diode

T/R

Table of Contents

Default Chapter2
- Acknowledgements2
- Important Notice3
- Cathodic Protection Tester Certification Application4
- Glossary of Terms10
- Examination Results12
- Nace Corrosion Network14
- Cathodic Protection Tester15
- Course Outline15
- The Course16
- Audience (Who Should Attend)17
- Experiments17
- Length17
- Prerequisites17
- Certification Application18
- Quizzes and Examinations18
- Attestation23
- Basic Electricity24
- Electrical Terms24
- Electrons24
- Voltage24
- Common Symbols for Voltage25
- Current25
- Resistance and Resistivity26
- Crossectional Area27
- Typical Resistivity of Common Materials28
- Electrical Schematic Diagram Symbols29
- Ohm’s Law30
- Electrical Laws30
- Basic DC Electrical Circuit30
- Electric Circuit30
- Current through a Resistor31
- Power32
- What Is the Current Flow?32
- Current Law33
- Kirchhoff’s Laws33
- Kirchhoff’s Voltage Law33
- Voltage Law33
- Kirchhoff’s Current Law34
- Series Circuit34
- Parallel Circuit36
- Series-Parallel Circuit38
- Series and Parallel Circuits Combined39
- Typical Alternating Current41
- Alternating Current (AC)41
- Pure Direct Current41
- Direct Current (DC)41
- DC Produced by Rectifying AC42
- Transformers42
- Impedance43
- Typical Transformer Wiring in a Rectifier43
- Meter Operation44
- Analog Meters45
- Basic Meter Movement45
- D'arsonval Movement (Voltmeter)46
- Ammeters47
- Ohmmeters47
- Voltmeters47
- Meter Hook up48
- Digital Meters48
- Basis of Operation48
- Resistor and Instrument Lab52
- Data Sheet54
- Diode Check55
- Measured Voltage Drops55
- Meter Fuses – Instructions for Replacement56
- Color Code for Resistors57
- Atoms58
- Basic Chemistry58
- Elements58
- Compounds (Molecules)59
- Ions59
- The Bohr Model of an Atom59
- Water Molecule60
- Acidity and Alkalinity (Ph)60
- Illustration of Acid and Alkaline Ph61
- Basic Electrochemistry62
- Effect of Ph on the Rate of Corrosion62
- Anodic Process (Half Reaction)63
- Oxidation63
- Cathodic Process (Half Reaction)64
- Reduction64
- Electrochemical Circuits65
- Electrolyte65
- Ionization65
- Anode Reactions66
- Corrosion Cell66
- Cathode Reactions67
- Typical Local Action Corrosion Cells on a Structure67
- External Circuit68
- Charge Transfer in the Electrolyte68
- Electron and Ion Flow68
- A Voltmeter Connection Is a Parallel Connection69
- Conventional Current Flow69
- Use of Voltmeters69
- Voltmeter Hook up69
- Current Direction70
- Polarity Sign70
- Sign Convention71
- Copper-Copper Sulfate Electrode72
- Reference Electrodes (Half-Cells)72
- Copper-Copper Sulfate Reference Electrode in Contact with Earth73
- Portable Copper-Copper Sulfate Reference Electrodes73
- Use and Care of Copper Sulfate Reference Electrodes74
- Elevation Difference Causes Water to Flow75
- Driving Force for Corrosion75
- Consumption Rate (K) for Various Metals76
- Corrosion Rate76
- Faraday’s Law76
- Polarization77
- Anode/Cathode Ratio78
- Factors that Affect the Corrosion Rate78
- Influence of the Environment78
- Moisture Content78
- Chemical Activity79
- Conductivity79
- Causes of Corrosion80
- Dissimilar Metals (Galvanic Corrosion)80
- Naturally Occurring Corrosion80
- Practical Galvanic Series81
- Alloying82
- Flashlight Battery as an Example of a Galvanic Cell82
- Graphite-Zinc Battery82
- Mechanical Stresses82
- Dissimilar Soils83
- Metal Ion Concentration Cell83
- Oxygen Concentration Cell83
- Temperature Differences in the Electrolyte83
- Metal Electrode Potentials in Tap Wate84
- Conclusions85
- Results85
- Corrosion-Cell86
- Potential Measurement87
- Polarized Potential Measurement88
- Current Direction in the External Circuit in Corrosion Cell89
- Experiment 2.3 Current Direction in the Electrolyte in Corrosion Cells92
- Reference Cell Maintenance94
- Conversions and Definitions96
- U.S. Customary/Metric Conversions98
- Materials Selection99
- Protective Coatings99
- Underground Corrosion Control99
- Underground or Submerged Structures99
- Bituminous Enamels100
- Exposure to Sunlight100
- Extruded Polyolefin and Polyethylene100
- Types of Mill Applied Underground Coatings100
- Two-Component Liquid Resin Coatings101
- Surface Preparation101
- Application101
- Girth Weld and Other Field Coatings101
- Electrical Isolation102
- Environmental Control102
- Maintenance Inspections102
- Adjustment of Ph103
- Inhibitors103
- Maintenance of Environmental Control103
- Cathodic Protection104
- Microscopic Corrosion Cell104
- Theory104
- Cathodic Protection on a Structure105
- Definition105
- Structures that Can be Cathodically Protected106
- Typical Galvanic Anode Cathodic Protection107
- Anodes107
- Galvanic Anode Systems107
- Applications of Galvanic Anode Systems108
- Advantages of Galvanic Anodes109
- Component Parts of Galvanic Systems109
- Limitations of Galvanic Anodes109
- Magnesium109
- Aluminum110
- Galvanic Anode Efficiency110
- Zinc110
- Attachment to Structures111
- Backfill111
- Size and Shapes111
- Specifications of Galvanic Anode Systems111
- Typical Impressed Current Cathodic Protection112
- Impressed Current Systems112
- Applications of Impressed Current Cathodic Protection113
- Power Sources113
- Advantages of Impressed Current Systems114
- Component Parts of Impressed Current Systems114
- Graphite114
- Limitations of Impressed Current Systems114
- Mixed Metal Oxide115
- Platinum115
- Conductive Polymer116
- Lead-Silver116
- Power Supply116
- Scrap Metal116
- Solar Panels117
- Cathodic Protection Rectifier Schematic117
- Engine-Generator Units118
- Wind Powered Generator Installation118
- Wind Powered Generators118
- Electrical Connections119
- Thermoelectric Generators119
- Coating120
- Factors Influencing Operation of Cathodic Protection120
- Moisture Content of Soil120
- Soil Texture120
- Glacial Till121
- Movement of Structure and Electrolyte121
- Oxygen Content121
- Temperature121
- Metal122
- Electrical Shielding122
- Make up of the Electrolyte122
- Cathodic Shielding Due to a Shorted Casing122
- Criteria for Cathodic Protection123
- Dielectric123
- NACE International Recommended Criteria123
- Ir Drop124
- Resistances124
- Voltage Drops in a Measuring Circuit124
- Recommended Criteria126
- Underground or Submerged Iron and Steel126
- Application of These Criteria127
- Structure-To-Electrolyte Potentials127
- Underground or Submerged Aluminum and Copper Piping128
- Offshore Platforms in Salt Water128
- Dissimilar Metal Situations128
- Above Ground Storage Tanks129
- Interiors of Steel Water Storage Tanks129
- Oil Heater-Treaters129
- Canada130
- International Standard ISO 15589-1130
- Steel Reinforced Concrete130
- Demonstrate Change in Polarized Potential with Time136
- Experiment to Demonstrate Change in Polarized Potential with Time136
- Safety138
- Safety Analysis Prior to Commencing Project138
- Electrical139
- Electrical Equipment (Rectifier) Case139
- Electrical Equipment (Rectifiers)139
- Cathodic Protection (CP) Rectifiers140
- Lock out / Tag out141
- Electrical Hazardous Areas142
- Explosions or Ignitions142
- Group Scissor Lock out / Tag out (LOTO)142
- Cathodic Protection Surveys143
- Induced AC Voltages144
- Excavations145
- Hazardous Material145
- Material Safety Data Sheets (MSDS)145
- Other General Precautions146
- Reaction Products146
- Calomel Reference Electrode148
- Field Measurements148
- Other Portable Reference Electrodes148
- Silver-Silver Chloride Reference Electrode148
- Stationary Reference Electrodes149
- Sulfate Reference Electrode149
- Basis of Measurement150
- Structure–To–Electrolyte Potential150
- Typical Applications150
- Voltmeter Ranges150
- Close Interval Potential Survey151
- Location of Reference Electrode151
- Pipe-To-Soil Potential Profile152
- Earth Current Flow and Surface Potential Measurements153
- Potential Measurement between Two Reference Electrodes153
- Recording Voltmeters153
- Voltage (IR) Drop in Potential Data153
- X-Y Plotters154
- Strip Chart Recorders154
- Data Loggers154
- Ammeter Connection155
- Measuring Current155
- Series Connection155
- Use of an Ammeter155
- Current Flow Sign156
- Current Range156
- Direction of Current Flow in an Ammeter Measurement156
- Clamp-On Ammeters157
- Shunts157
- Current Calculation158
- Shunt Measurement158
- Direction of Current Flow159
- Shunt Types and Values161
- Galvanic Anode Output162
- Current Flow on a Pipeline or Cable163
- Current Requirement Tests163
- Rectifier Current Output163
- 2-Wire Line Current Test164
- Steel Pipe Resistance166
- Table of Pipe Resistances166
- 4-Wire Line Current Test167
- Bond Current169
- Measuring Resistance169
- Typical Measurements169
- Using Ohm’s Law169
- Isolation Joint Test Using an Ohmmeter170
- Using an Ohmmeter170
- Purpose and Usage171
- Electrical Continuity171
- Accidental Contacts172
- Isolation (Insulating) Joints172
- Measuring Structure Continuity173
- Methods for Testing an Isolation Fitting Include173
- Testing Resistance between a Pipe and Casing173
- Diode Bias174
- Four-Pin (Wenner) Method of Measuring Soil Resistivity175
- Measuring Electrolyte Resistivity175
- Wenner Four-Pin Method175
- Average and Layer Resistivity176
- Resistivity Soil Box177
- Soil Box177
- Single Probe Soil Resistivity Measurement178
- Resistivity Probe178
- Measuring Ph178
- Use of Pipe Locating Devices179
- Conductive180
- Conductive Pipe Locator Principle180
- Example of a Conductive Pipe Locator181
- Inductive181
- Inductive Pipe Locator Principle181
- Coupon Measurements182
- Current Interrupter182
- Use of Current Interrupters182
- Definitions184
- Effects184
- Sources184
- Types of Stray Current185
- Steady State Stray Current185
- Dynamic Stray Current185
- Measurement Indications186
- Proximity of Possible Sources186
- Recording of Dynamic Stray Currents186
- Identification of Stray Current186
- Location of Foreign Structures and Rectifiers188
- Pipe-To-Soil Data Plot Indicating Cathodic Interference188
- Mitigation Bonds189
- Stray Current Corrosion Control189
- Mitigation with Cathodic Protection191
- Demonstration of Cathodic Interference192
- Reasons for Monitoring194
- Monitoring Cathodic Protection195
- Monitoring Requirements195
- Technical197
- Date, Time, and Weather197
- Recordkeeping197
- Importance of Good Record Keeping197
- Computer Records and Spreadsheets198
- Facility Maps and Work Documentation198
- Site Conditions198
- Sketches198
- Test Stations200
- Construction Notes201
- Environmental Factors201
- Types of Test Stations202
- Typical Post Mounted Potential Measurement Test Station202
- IR (Millivolt) Drop (Current Span)203
- Typical Flush Mounted Potential Measurement Test Station203
- Pipe Casing204
- IR Drop Test Station204
- Casing Test Station205
- Foreign Line Crossing205
- Foreign Line Crossing Test Station206
- Isolating Joint206
- Isolating Coupling207
- Isolating Union207
- Isolating Flange208
- Properly Isolated Casing208
- Coupons209
- Isolation Joint Test Station Mitigation Bond209
- Typical Coupon Test Station210
- Thermite (Exothermic) Welding211
- Wire Attachment211
- Thermite Weld Process212
- Galvanic (Sacrificial) Anodes213
- Mechanical213
- Prepackaged Anodes214
- Multiple Prepackaged Vertical Anodes215
- Single Prepackaged Vertical Anode215
- Bracelet Anodes216
- Non Packaged Anodes216
- Ribbon or Strip Anodes216
- Offshore Anodes217
- Typical Bracelet Anode217
- Aluminum Alloy Anodes for Offshore Structures218
- Impressed Current Groundbeds218
- Handling and Inspection of Anodes and Cable219
- Prepackaged Impressed Current Anode220
- Surface Groundbed Configurations221
- Vertical Anode Installation221
- Horizontal Anode Installation222
- Header Cable Installation223
- Horizontal Impressed Current Anode223
- Distributed Anode Configuration224
- Surface Remote Groundbed Configuration224
- Deep Anode Groundbed Configuration225
- Distributed Anode Groundbed Protecting Wharf Piling225
- Surface Distributed Anode Groundbed Configuration225
- Deep Anode Installation227
- Negative Circuit227
- Installation of Rectifiers or Other Power Sources228
- Rectifiers228
- DC Output229
- Anode Circuit (Positive Circuit)229
- AC Power and Wiring229
- Troubleshooting230
- Current Profile231
- Illustration of Shorted Structure231
- Testing a Pipeline231
- Locating a Short through Current Flow232
- Tone Generator232
- Casing Shorts233
- Using Audio Tone Locator to Find Shorts233
- Resistance Testing between a Casing and a Pipeline234
- Isolating Joint Shorts235
- Resistance Test Set-Up for an Isolating Joint235
- Cathodic Protection Levels236
- Improper Backfill237
- Galvanic and Impressed Current Groundbeds237
- Groundbed Malfunctions237
- Anode Deterioration237
- Drying of Soil238
- Routine Maintenance238
- Output Problems239
- Zero Current and Voltage Outputs239
- Locating a Short Circuit in a Rectifier Circuit240
- Significant Changes in both Voltage and Current Outputs241
- Significant Current Change with Unchanged Voltage241
- Zero Current Output with Unchanged Voltage Output241
- Appended Documents242
- Primary Reference244
- Nace Glossary of Corrosion-Related Terms247
- Reference Electrode Classifications265
- Element Types265
- Factors Affecting the Accuracy of Reference Electrodes265
- Electrolyte Types265
- External Influences266
- Lights Effects266
- Reference Potential266
- Temperature Effects266
- Contamination Effects267
- Design Life of Permanent Cells267
- Electrolyte Concentration Effects267
- References268
- Standard Recommended Practice269
- Table of Contents271
- NACE International Standard Recommended Practice271
1 General272
2 Definitions272
3 Determination of Need for External Corrosion Control274
- Economic Factors Include the Following274
4 Piping System Design275
- External Corrosion Control275
- Corrosion Control Test Stations276
5 External Coatings277
- Storage, Handling, Inspection, and Installation278
6 Criteria and Other Considerations for Cathodic Protection283
- Criteria for Copper286
- Criteria for Aluminum286
- Criteria for Steel and Cast Iron286
- Additional References286
- Bibliography for Section 6286
7 Design of Cathodic Protection Systems288
- Design Drawings and Specifications291
- Bibliography for Section 7291
8 Installation of Cathodic Protection Systems292
- Construction Specifications292
- Construction Supervision292
- Installing Anodes292
9 Control of Interference Currents293
- Mechanism of Interference-Current Corrosion293
10 Operation and Maintenance of Cathodic Protection Systems295
11 External Corrosion Control Records296
- Installation of Interference Mitigation Facilities297
- References298
Appendix A-Interference Testing299
Appendix B-Method for Determining Probable Corrosion Rate and Costs of Maintaining Service300
Appendix C-Contingent Costs of Corrosion300
Appendix B-Costs of Corrosion Control300
- Recommended Practice302
- NACE International Standard304
- Definitions305
- General305
- Cathodic Protection of New UST Systems306
- Structures in Selected Oil Provinces356
Appendix A-Typical Design Parameters for Offshore Petroleum Production356
- Design Criteria for Cathodic Protection Systems358
- Resistivities (Ohm-CM) Temperature358
- A1: Current Density/Temperature Curves359
Appendix B-Energy Capabilities and Consumption Rates of Various Commercial Galvanic Anodes Available for Cathodic Protection of Offshore Structures359
Appendix C-Consumption Rates in Seawater of Various Commercial Types of Impressed Current Anodes Available for Cathodic Protection of Offshore Structu360
Appendix D-Typical Method for Calculation of Galvanic Anode Current Output Using Initial, Maintenance, and Final Current Densities360
Appendix E-Typical Method of Calcuation of Galvanic Anode Current Output Using Design Slope and Maintenance Current Density362
- Seawater362
- General367
- Definitions367
- Determination of the Need for Cathodic Protection368
Appendix A-Wire Gauge Conversions395
- Human Resistance to Electrical Curren389
- Internal Cathodic Protection Systems in Oil-Treating Vessels396
- Definitions399
- General399
- Design and Selection of Cathodic Protection System400
- Determination of Need for Cathodic Protection400
- Anode Installation402
Appendix A-Glossary of Terms452
Appendix B-Additional Information Useful for Design453
Appendix C-Test Equipment454
- Steel-Cased Pipeline Practices455
- Definitions458
- Design458
- General458
- Installation459
- Maintenance and Repair461
- Monitoring462
- Bibliography463
- References463
Appendix A: Typical Casing-Filling Procedures464
Appendix B: Monitoring Techniques465
- Establishing a Circuit for a Four-Wire IR Drop Test469
- Four-Wire IR Drop Test469
- Establishing the Circuit (Downstream [D/S] End)470
- Alternate Method: Lineal Conductance Values for the Casing472
- Casing Depolarization Test472
- Cycling the Rectifier472
- Casing Clear473
- Casing Shorted473
- Use of Pipe/Cable Locator474
- Pipe Data475
- Standard Test Method478
- NACE International Standard Test Method480
- Definitions481
- General481
- Instrumentation and Measurement Guidelines483
- Safety Considerations483
- Instrument Accuracy484
- Pipe-To-Electrolyte Potential Measurements484
Appendix A: Reference Electrodes498
- Measurement Techniques for Net Protective Current499
- Two-Reference-Electrode Surface Survey499
Appendix B: Net Protective Current499
- Pipe-To-Electrolyte Potential Survey501
- Cathodic Protection Using the Net Protective Current Technique502
- Direction of Survey Travel503
- Surface Potential Survey503
Appendix C: Using Coupons to Determine Adequacy of Cathodic Protection505
- Definitions512
- General512
- Instrumentation and Measurement Guidelines514
- Safety Considerations514
- Tank-To-Electrolyte Potential Measurements515
Appendix A: Using Coupons to Determine the Adequacy of Cathodic Protection532