UFC 3-570-06
JANUARY 31 2003
percent. It is important that replacement anodes be of the same type as the originals,
as the design of the system is dependent on the anode material used, unless
replacement of the entire system is accomplished. Anodes of the incorrect type could
lead to insufficient protection.
Table 2-5. Composition of Magnesium Anodes
ELEMENT
STANDARD
HIGH POTENTIAL
Aluminum
5.3 - 6.7%
0.1% max
0.15% min
0.5 - 1.3%
Zinc
2.5 - 3.5%
Copper
0.2% max
0.02% max
Silicon
0.1% max
Iron
0.003% max
0.03% max
Nickel
0.002% min
0.001% max
Other Metals
0.3% maxi
0.3% max total
0.05% max. each
Magnesium
Remainder
Remainder
2-6.1.2
Zinc Anodes. Zinc anodes are commonly available in weights from 2.27
kilograms to 113.4 kilograms (5 pounds to 250 pounds) in the form of plates, bars, and
rods as shown in MIL-HDBK-1004/10 (Table 2-10). Zinc is also available as ribbon
anodes in 16-millimeter by 22.2-millimeter (5/8-inch by 7/8-inch), 13-millimeter by 14.3-
millimeter (1/2-inch by 9/16-inch), and 8.7-millimeter by 11.9-millimeter (11/32-inch by
15/32-inch) sizes, each with a 2.5-millimeter (1/10-inch) diameter galvanized steel wire
core. Zinc anodes are most commonly used in immersion service either in fresh or salt
water. They are, however, occasionally used in the protection of buried structures when
special circumstances are encountered, usually in soil resistivities below 2,000 ohm-
centimeters with extremely well coated structures. Two zinc anode compositions are
commonly available. They are a standard alloy formulated for use in fresh water and
soil and an alloy specially formulated for use in seawater. The composition of these
alloys is given in Table 2-6. As is the case for magnesium alloy anodes, consumed zinc
anodes should be replaced with zinc anodes of the same type and size as those
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