UFC 3-570-06
JANUARY 31 2003
Figure 2-14. Stray Current Corrosion Cell Caused by an HVDC Transmission
System
POWER
(+)
conversion
conversion
unit
unit
Unbalanced
AC
AC
Ground
Ground
conversion
conversion
(-)
unit
unit
2-2.4.3
Welding Operations. DC welders are a source of DC current. One
example of this type of electrochemical corrosion cell occurs when an electric welding
machine on board a metallic ship with a grounded DC line on shore forces the current to
leave the bottom of the ship (anode) to return to the grounding system (cathode).
Figure 2-15. Stray Current Corrosion Cell Caused by a DC Welding Operation
DC Welder
Metal Boat
Ground Rod
Anode
Cathode
Current Flow in the Earth
2-2.4.4
Cathodic Protection Systems. Cathodic protection systems are a major
source of stray current on other metallic structures. An example of this electrochemical
corrosion cell is when a foreign pipeline passes near an anode, and then crosses the
protected structure (cathode). Detailed procedures are provided for testing and
mitigation of these problems in Chapter 7.
2-18
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