CP 2 Course Manual_April 2005.pdf - CP 2\u2013Cathodic Protection Technician Course Manual April 2005 \u00a9 NACE International 2000 Acknowledgements The time

CP 2 Course Manual_April 2005.pdf - CP 2–Cathodic...

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Unformatted text preview: CP 2–Cathodic Protection Technician Course Manual April 2005 © NACE International, 2000 Acknowledgements The time and expertise of a many members of NACE International have gone into the development of this course. Their dedication and efforts are greatly appreciated by the authors of this course and by those who have assisted in making this work possible. The scope, desired learning outcomes and performance criteria were prepared by the Cathodic Protection Training and Certification Program Task Group under the auspices of the NACE Certification and Education Committees. Special thanks go to the following: On behalf of NACE, we would like to thank the following members who were instrumental in the development and review of this program. Buddy Hutson Steve Bean Joe C. Bowles, Jr. Raul Castillo David Edwards Gerry Garleiser Kevin Garrity Robert Gummow Brad J. Lewis Thomas H. Lewis Ed Ondak Larry Rankin John Schmidt David A. Schramm William H. Thomason Southern Cathodic Protection, Apopka, Florida Southern California Gas Company, Los Angeles, California Tellepsen Gas Pipeline Services, Houston, Texas Dow Chemical, Freeport, Texas Santa Fe Pipelines, Rocklin, California Exxon Co. USA, Houston, Texas CC Technologies, Dublin, Ohio CorrEng Consulting Service Inc., Downsview, Ontario Kinder Morgan Energy Partners L.P., Tucson, Arizona LORESCO, Inc., Hattiesburg, MS EJ Ondak Associates, Inc, Littleton, Colorado Corrpro Companies Inc., Houston, Texas Duke Energy, Houston, Texas ENEngineering, Woodridge, Illinois Conoco, Inc. Ponca City, Oklahoma This group of NACE members worked closely with the contracted course developers, who were John Fitzgerald, John Wagner, and Walter Young of Corrpro Cos. Inc. Much of the material in the courses is based on existing NACE cathodic protection training material which was developed and refined over several years by members including Robert A. Gummow, (CorrEng, Downsview, Ontario), James R. Myers (JRM Associates, Franklin, Ohio), Frank Rizzo (FERA Corporation, Houston, Texas), Marilyn Lewis, P.E. (Lewis Engineering, Hattiesburg, MS), Larry Brandon (CorPre Tek, Inc., Hubbardston, MI) and James F. Jenkins, P.E. (Cambria, California). IMPORTANT NOTICE: Neither the NACE International, its officers, directors, nor members thereof accept any responsibility for the use of the methods and materials discussed herein. No authorization is implied concerning the use of patented or copyrighted material. The information is advisory only and the use of the materials and methods is solely at the risk of the user. Printed in the United States. All rights reserved. Reproduction of contents in whole or part or transfer into electronic or photographic storage without permission of copyright owner is expressly forbidden. CP 2–CATHODIC PROTECTION TECHNICIAN COURSE MANUAL TABLE OF CONTENTS General Information Course Outline Introduction CP 2–Cathodic Protection Technician Certification Application Section 1 Chapter 1—Corrosion Theory The Corrosion Cell .....................................................................................1:1 Driving Force for Corrosion ..................................................................1:3 Voltage ...............................................................................................1:3 Metal...................................................................................................1:3 Electrolyte...............................................................................................1:9 Concentration Cells..........................................................................1:10 Corrosion Rate..........................................................................................1:14 Faraday’s Law ......................................................................................1:14 Voltage Difference ...............................................................................1:15 Reference Electrodes (Half-Cells) .......................................................1:15 Polarization...........................................................................................1:23 IR Drop.............................................................................................1:26 Factors Affecting Polarization.........................................................1:27 Passivity................................................................................................1:31 Passivating vs. Nonpassivating........................................................1:31 Forms of Corrosion ..................................................................................1:33 Experiment 1.1 Investigation of Changes in Corrosion Cell Operation to Changes in the Electrolyte .............................................1:36 Exercise 1.1 Resistor and Instrument Lab ...............................................1:38 CP 2–Cathodic Protection Technician Course Manual © NACE International, 2000 04/15/05 Section 2 Chapter 2—Cathodic Protection Fundamentals Concept of Cathodic Protection .................................................................2:1 Polarization of a Structure..........................................................................2:2 Current Requirement ..................................................................................2:4 Surface Area ...........................................................................................2:4 Polarization.............................................................................................2:6 Effect of Environment pH on CP Current Requirement.......................2:6 Temperature Effect on CP Current Requirement..................................2:7 Effect of Oxidizers on CP Current Requirement ..................................2:9 Effect of Relative Movement Between the Structure and Electrolyte on CP Current Requirements .........................................2:10 Applied Current vs. Corrosion Rate ....................................................2:11 Criteria for Cathodic Protection...............................................................2:13 RP0169 Criteria....................................................................................2:13 Basis of RP0169 Criteria......................................................................2:14 Polarized Potential................................................................................2:16 Application of Criteria .........................................................................2:19 Other Criteria........................................................................................2:20 International Standard ISO 15589-1 ........................................................2:23 American Water Works Assocation ........................................................2:23 Non-NACE International Criteria............................................................2:24 E log I........................................................................................................2:27 Section 3 Chapter 3—Cathodic Protection Systems Components of Galvanic Cathodic Protection ..........................................3:1 Anodes ....................................................................................................3:1 Anode Backfill .......................................................................................3:5 Wiring and Connections.........................................................................3:6 Components of Impressed Current Cathodic Protection...........................3.6 Applications of Impressed Current Cathodic Protection ......................3:7 Anodes ....................................................................................................3:7 Anode Backfill .....................................................................................3:10 Power Supply .......................................................................................3:11 Wiring and Connections.......................................................................3:11 Environmental Issues ...............................................................................3:12 Anode Configurations ..............................................................................3:13 Galvanic Anodes ..................................................................................3:16 Impressed Current Anodes...................................................................3:17 CP 2–Cathodic Protection Technician Course Manual © NACE International, 2000 04/15/05 Experiment 3.1 Demonstrate the Use of a Sacrificial Anode to Mitigate Corrosion in a Local Action Cell .....................................3:19 Experiment 3.2 Demonstrate the Used of an Impressed Current System to Mitigate Local Action Cell Corrosion ...............................3:24 Section 4 Chapter 4—DC Power Sources for Cathodic Protection Transformer-Rectifier.................................................................................4:1 Circuit Breakers......................................................................................4:2 Transformer ............................................................................................4:4 Rectifying Circuits .................................................................................4:5 Bridge Circuits ...................................................................................4:5 Center Tap Circuits ............................................................................4:9 Silicon-Controlled Rectifiers (SCR)................................................4:11 Switching-Mode Rectifiers..............................................................4:14 Pulse Rectifier ..................................................................................4:15 Operational Modes...........................................................................4:16 Other Rectifier Components ............................................................4:18 Other Power Sources................................................................................4:20 Engine Generator Sets..........................................................................4:20 Thermoelectric Generators...................................................................4:20 Solar Power Supplies ...........................................................................4:22 Wind-Driven Generators......................................................................4:23 Batteries ................................................................................................4:24 Fuel Cells..............................................................................................4:25 Rectifier Testing .......................................................................................4:26 Output Problems...................................................................................4:26 Circuit Diagrams ..................................................................................4:32 Electrical Damage ................................................................................4:32 Efficiency Test .....................................................................................4:32 Filters ....................................................................................................4:33 Detection of Cable Breaks ...................................................................4:33 Testing Transformers ...........................................................................4:34 CP 2–Cathodic Protection Technician Course Manual © NACE International, 2000 04/15/05 Section 5 Chapter 5—Safety Introduction.................................................................................................5:1 Electrical .....................................................................................................5:2 Electrical Equipment (Rectifiers) ..............................................................5:3 Electrical Equipment (Rectifier) Case...................................................5:3 Cathodic Protection Rectifiers ...............................................................5:3 Lock Out / Tag Out ....................................................................................5:4 Electrical Hazardous Areas ........................................................................5:5 Explosions or Ignitions...............................................................................5:5 Cathodic Protection Surveys......................................................................5:6 Induced AC Voltages .................................................................................5:7 Excavations.................................................................................................5:8 Hazardous Material ....................................................................................5:8 Material Safety Data Sheets (MSDS) ........................................................5:8 Reaction Products.......................................................................................5:9 Other General Precautions .........................................................................5:9 Section 6 Chapter 6—Field Measurements General........................................................................................................6:1 Measurement of Cathodic Protection Effectiveness .................................6:1 Structure-to-Electrolyte Potentials.............................................................6:2 The Potential Measurement Circuit and Measurement Error ...............6:3 Voltage Drop Errors in the Potential Measurement Due to Current in the Pipeline ......................................................................6:10 IR Drop Error Determination and Correction .....................................6:10 Current Interruption .........................................................................6:11 Reference Electrode Near the Structure ..........................................6:15 External CP Coupons.......................................................................6:17 Reference Electrode at Remote Earth..............................................6:19 Stepwise Current Reduction Method ..............................................6:20 Surface Potential Surveys ........................................................................6:23 Close Interval Potential Survey ...........................................................6:24 Analysis of Surface Potential Surveys.................................................6:26 Surveys of Cathodically Protected Structures.................................6:26 Lateral/Side Drain Surface Surveys ................................................6:29 Current Measurement...............................................................................6:29 Using an Ammeter to Measure Current...............................................6:30 Using a Shunt to Determine Current Magnitude.................................6:31 CP 2–Cathodic Protection Technician Course Manual © NACE International, 2000 04/15/05 Zero Resistance Ammeter....................................................................6:32 Clamp-On Ammeter.............................................................................6:33 Pipeline Current Measurements...........................................................6:34 Uses ..................................................................................................6:34 Use of a Clamp-On Ammeter..........................................................6:35 2-Wire Line Current Test.................................................................6:35 4-Wire Line Current Test.................................................................6:38 Earth Current Measurements ...............................................................6:40 Non-Cathodically Protected Structures ...............................................6:40 Surface Coating Evaluation Techniques on Buried Pipelines ................6:43 Pearson Survey .....................................................................................6:43 Direct Current Voltage Gradient (DCVG) Survey..............................6:46 Pipeline Current Mapping....................................................................6:50 Coating Resistance Calculations..........................................................6:50 Current Requirement Tests ......................................................................6:53 Electrical Isolation....................................................................................6:55 Indication of Problems .........................................................................6:55 Locating the Problem ...........................................................................6:55 Use of a Pipeline/Cable Locator for Isolation Testing....................6:56 Testing Above Grade Isolating Flange/Unions...................................6:57 Structure-to-Electrolyte Potential for Isolation Testing......................6:58 Interrupted Structure-to-Electrolyte Potential to Test Isolation..........6.59 DC Line Current to Test Isolation .......................................................6:59 Fixed Cell to Moving Ground for Continuity Test .............................6:60 Current Response .................................................................................6:61 Casings......................................................................................................6:62 Indication of Problems .........................................................................6:62 Locating the Problem ...........................................................................6:62 Soil Resistivity Testing ............................................................................6:66 Purposes................................................................................................6:66 Measurement Techniques ....................................................................6:66 Measuring pH ...........................................................................................6:75 Concrete Structures ..................................................................................6:75 Direct Inspection ......................................................................................6:77 Leak Frequency ........................................................................................6:77 In-Line Inspection ....................................................................................6:78 CP 2–Cathodic Protection Technician Course Manual © NACE International, 2000 04/15/05 Section 7 Chapter 7—Stray Current and CP Interference Stray Current...............................................................................................7:1 Dynamic Currents.......................................................................................7:2 Sources of Dynamic Stray Currents ......................................................7:2 Detecting Dynamic Stray Currents........................................................7:3 Static (Steady State) Currents ....................................................................7:6 Cathodic Interference .................................................................................7:7 Anodic Interference................................................................................7:8 Detection of Static Interference Currents ..............................................7:8 Sample Field Data ....................................................................................7:11 Structure-to-Electrolyte Potentials.......................................................7:11 Current Measurements .........................................................................7:12 Resolving Interference Problems..................................................
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