MIL-HDBK-1004/10

High

Standard

Potential

High

Magnesium

Magnesium

Purity

Alloy

Alloy

Zinc

Zinc

For protection of

40,000

96,000

120,000

40,000

well coated structures

For protection of poorly

50,000

120,000

190,000

50,000

coated or bare structures

f

=

anode size factor from Table 3

y

=

structure potential factor from Table 4

p

=

electrolyte resistivity in ohms-cm

The number of anodes is then determined by dividing the total

current required by the output per anode. The expected anode life is

estimated based upon the practical deterioration rate for the selected anode

material. Magnesium is consumed at a typical rate of 17 pounds per ampere

year (lbs/A yr), zinc at 26 lbs/A yr, and typical aluminum alloy anodes at 11

lbs/A yr. As the actual design is an iterative process, such factors as anode

size or material may be adjusted in order to optimize the system being

designed.

More precise calculations for the design of sacrificial anode

cathodic protection systems are given in Section 7. Examples of typical

designs using both sacrificial anode and impressed current systems are given

in Section 8.

For the

4.2.6

Basic Design Procedure for Impressed Current Systems.

design of impressed current systems three steps are taken.

Total Current Determination. The first step is the same as for

4.2.6.1

sacrificial anode systems, namely the determination of the total current

required either from actual current requirement measurements or by multiplying

a typical current requirement (from Tables 1 or 2) by the surface area of the

structure to be protected.

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