Fe Si Anodes
Are the most common impressed current anodes
Are used in soil, water or sea water
Come in two grades; FeSi and FeSiCr for sea water applications
Anode typical chemical composition as well as electrochemical properties are shown in the coming slide.
Anodes could be a single head type or double head, solid or tubular.
Cable connection to anode shall be handled with great care.
There are numerous methods of cable connections to anode.
Composition, ASTM A518 Grade 3
| Silicon | 14.20 - 14.75% |
|---|---|
| Chromium | 3.25 - 5.00% |
| Manganese | 1.50% max |
| Carbon | 0.70 -1 .10% |
| Copper | 0.50% max |
| Molybdenum | 0.20% max |
Electrochemical properties
| Average soil resistivity along grounded, Ohm cm | Maximum Amps per anode in a coke breeze column, 12" OD by 60" | Equivalent current density on surface of coke breeze column, Milliamps/sq ft |
|---|---|---|
| Less than 1000 | 2.00 | 127 (see note) |
| 1000 - 1500 | 1.75 | 111 (see note) |
| 1500 - 2000 | 1.50 | 96 |
| 2000 - 3000 | 1.25 | 80 |
| Over 3000 | 1.00 | 64 |