UFC 3-570-06
JANUARY 31 2003
6-4
OTHER CONSIDERATIONS ............................................................ 6-4
6-4.1
Determining Voltage Drops ............................................................... 6-5
6-4.2
Sound Engineering Practices............................................................ 6-5
6-4.3
In-Line Inspection of Pipes................................................................ 6-5
6-4.4
Stray Currents and Stray Electrical Gradients .................................. 6-5
6-5
ALTERNATIVE REFERENCE ELECTRODES ................................. 6-5
6-5.1
Alternative to Saturated Copper / Copper Sulfate ............................ 6-5
6-5.2
Alternative Metallic Material or Structure .......................................... 6-5
CHAPTER 7 TESTING
Paragraph
7-1
POTENTIAL MEASUREMENT ......................................................... 7-1
7-2
SOURCES OF ERROR .................................................................... 7-1
7-2.1
Accuracy of the Reference Electrode................................................ 7-1
7-2.2
IR Drop Error..................................................................................... 7-3
7-2.3
Anode Gradient Error ........................................................................ 7-4
7-2.4
Contact Resistance Error .................................................................. 7-5
7-2.5
Mixed Potential Error......................................................................... 7-6
7-3
PRACTICAL MEASUREMENT OF CATHODIC PROTECTION
POTENTIALS .................................................................................... 7-7
7-3.1
Test Criteria Selection....................................................................... 7-7
7-3.2
Test Methods for the -0.85 ON Criterion ........................................... 7-9
7-3.3
Test Methods for the -0.85 Instant-OFF Criterion ............................. 7-11
7-3.4
Test Methods for the 100mV Polarization Criterion .......................... 7-11
7-3.5
Instant-OFF Test Methods ................................................................ 7-11
7-3.6
Types of Interrupters ......................................................................... 7-12
7-3.7
Specific Methods for Various Instant-OFF Potential Measurement
Techniques ....................................................................................... 7-13
7-4
STRUCTURE-TO-SOIL POTENTIAL LIMITS ................................... 7-17
7-4.1
Excessive Cathodic Protection Current............................................. 7-17
7-4.2
Water Storage Tanks ........................................................................ 7-18
7-4.3
Underground Structures.................................................................... 7-18
7-4.4
Uncoated Structures ......................................................................... 7-19
7-5
CELL-TO-CELL POTENTIAL TESTING PROCEDURES ................. 7-19
7-5.1
Performing Test................................................................................. 7-19
7-5.2
Accuracy ........................................................................................... 7-20
7-6
RECTIFIER EFFICIENCY TESTING PROCEDURES ...................... 7-21
7-6.1
Determining Efficiency ...................................................................... 7-21
7-6.2
Alternate Procedure .......................................................................... 7-21
7-6.3
Expected Efficiency........................................................................... 7-22
7-7
DIELECTRIC TESTING PROCEDURES .......................................... 7-22
7-7.1
Testing for a Shorted Dielectric......................................................... 7-23
7-7.2
Using a Radio Frequency Tester ...................................................... 7-25
7-7.3
Using a Pipe Locator......................................................................... 7-25
7-7.4
Using a Temporary Local Cathodic Protection System..................... 7-27
7-8
CASING TESTS ................................................................................ 7-27
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