MIL-HDBK-1004/10
d)
Design for 1 mA/ft of bare pipe after polarization.
e)
Magnesium packaged type anodes must be used.
f)
System is adequately insulated from foreign structures.
g) All pipe was mill-coated with hot applied coal-tar enamel and
wrapped with asbestos felt. Coating was tested over the trench for holidays,
and defects were corrected. Coating is assumed better than 99.5 percent
perfect at installation.
(See Figure 112)
9.9.2
a) Total outside area of liquid fuel piping serving the hydrant
refueling area:
Pipe Length (ft)
Pipe Area (ft/ft)
Pipe Size (in)
3
(defueling header)
2 x 293
=
586
586
x
0.916
=
537
6
(defueling return)
90
90
x
1.734
=
156
8
(refueling header)
2 x 293
=
586
586
x
2.258
=
1,323
10
(supply line)
90
90
x
2.814
=
253
6
(hydrant laterals)
3 x 960
= 2,880
2,880
x
1.734
=
4,995
Total area of POL pipe in ft
7,264
b) Area of bare pipe based on 90 percent coating efficiency
(coating efficiency deteriorates from 99.5 percent to 90 percent in the
15-year life of the cathodic protection system):
A
=
7,264 x 0.1
A
=
726 ft
c) Maximum current required based on 1 mA/ft of bare pipe:
I = 1.0 mA/ft x 726 ft
I = 726 mA or 0.73 A
196
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