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Preface to Third Edition vii
Preface to First Edition ix
1 Soil Resistivity Surveys 1
Soil Resistivity Units. Two-Terminal Resistivity Determination. Four-
Terminal Resistivity Determination. Other Methods. Locating Hot
Spots on Bare Lines. Surveys for Ground Beds. Area Surveys. Logarithmic
Resistivity Ranges. Summary.
2 Potential Surveys 16
Pipe-to-Soil Potentials: Electrodes. Electrode Placement. Pipe Line
Connection. Surface Potential Survey for Corrosion. Pipe-to-Soil Potential
as a Criterion of Cathodic Protection. Other Applications of
Pipe-to-Soil Potentials. Other Criteria. Summary.
3 Line Currents 31
Measurement of Line Current in Test Section. Stray-Current Studies.
Long-Line Currents. Cathodic Protection Tests. Coating Conductance
Measurement. Summary.
4 Current Requirement Surveys 36
The Problem: Coated Lines. Principles of Current Requirement Test.
Current Sources for Tests. Temporary Ground Beds. Special Conditions.
Summary.
5 Rectifier Systems for Coated Lines 45
General Design Principles. Attenuation Curves. Line Termination. Anode
Proximity Effects. Attenuation with Multiple Drain Points. Design
Procedure. An Alternate Method. The Economic Balance. Summary.
v
6 Ground Bed Design and Installation 59
Design Principles. Disturbing Factors. Field Modification. Installation
Methods. High-Silicon Iron Anodes. Steel Anodes. Horizontal Graphite
Anodes. Deep Anodes. A Typical Ground Bed Installation. Summary.
7 Galvanic Anodes on Coated Lines 78
When and Where to Use Magnesium. When and Where to Use Zinc.
General System Design. Installation Procedure. Polarization and Final
Adjustment. Modification of Process with Experience. Sample Problems.
Summary.
8 Hot Spot Protection 88
What "Hot Spots" Are. Hot Spot Protection. Locating Hot Spots. Anode
Selection and Spacing. Field Installation. Field Design. Zinc Anodes
in Hot Spot Protection. Installation Details. Supervision and Control.
Summary.
9 Stray-Current Electrolysis 100
Stray Current Corrosion. Sources of Stray Currents. Detection of Stray
Current. Remedial Measures. Negative Bus Bonding. Exposure Areas.
Potential Surveys. Secondary Exposure. Summary.
10 Interference in Cathodic Protection 109
The Problem. Basic Solutions. Design. Crossing Bonds. Calculation of
Bond Resistance. Multiple Bonds. Auxiliary Drainage. Parallel Lines.
Radial-Flow Interference. Foreign Lines with Insulating Joints. Summary.
11 Operation and Maintenance 125
Importance of Adequate Supervision. Failures in Rectifier-Ground Bed
Systems. Failures in Magnesium Anode Systems. Minimum Inspection
Schedule for Rectifier System. Minimum Inspection Schedule for Anodes.
Monitor System. Troubleshooting. Summary.
12 Coating Inspection and Testing 136
Construction Inspection. Evaluation of Coating in Place. Coating or
Leakage Conductance. Pearson Surveys. Accelerated Coating Tests.
Summary.
Appendix A Fundamentals of Corrosion 146
Appendix B Cathodic Protection of Steel in Soil 150
Appendix C Corrosion of Steel in Soil 153
Appendix D Attenuation Equations 160
Index 163
vi
Preface to Third Edition
A pipe line buried in the earth represents a challenge. It is made of
steel—a strong, but chemically unstable, material—and is placed in an
environment which is nonuniform, nonprotective, and nonyielding. It is
the duty of the corrosion engineer to study the properties of this system
to ensure that the pipe line will not deteriorate.
In 1955, when I was first working on cathodic protection for pipe
lines in Saudi Arabia, the first edition of this book by Marshall Parker
was just a year old. Fortunately, the company library contained Mr.
Parker's book. I found its simplicity and directness preferable in approaching
a complex subject.
During the 30 years since its publication, generations of pipe line engineers
and technicians have used this book as their first exposure to
corrosion control. Many books on the subject have been published since
1954, but the Parker book is still the best introduction to the fundamentals.
New technology has been developed, yet the principles of cathodic
protection are still the same. The result is that we have more sophisticated
instruments to use, but the measurements have not changed. Consequently,
I have retained the still-valid material of the original Marshall
text and made changes only when better and shorter methods are available.
The first task of the pipe line corrosion engineer is to study the properties
of the earthen environment. First, we shall learn how to measure
the resistivity of the soil as a preparation for further work. In the second
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