Aluminum (Aluminium) Anodes
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The electrochemical performance of aluminum
makes it an attractive galvanic anode material, especially in low
resistivity applications such as seawater and produced brines. Compared
to the performance of magnesium, aluminum's lower driving potential and
high current capacity per pound are key aspects for its use in long life
saline systems.
For years, the low current efficiency of
commercially available aluminum hindered its use in cathodic protection |
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systems. The high efficiency
alloy series were developed to correct this problem and have become the
industry standard. Modern aluminum anodes stand out with respect to:
Indium activated anodes are recommended for use in seawater, saline
mud, at both ambient and high temperatures, and in hot brines including most oil
field brines. Indium activated tank anodes are recommended for
use in hot brine and oil field brine applications. This alloy provides a longer
life, reducing costs for protecting tanks containing oil field brine. Aluminum
anodes can be installed by suspending anodes from the deck of the tank from a
deck mount. Or the anodes can be placed on concrete or tile blocks placed in the
bottom of the tank. Many of the anodes can also be installed by welding or
bolting the anode core to the structure. In most cases it is recommended that
the lead wire from the anodes be attached to the outside of the vessel. A shunt
should be placed in series with the lead wire to measure the current output in
order to determine the life expectancy of the anodes.
Aluminum platform anodes are supplied in a variety of shapes and sizes for
seawater applications; for example,
offshore pipelines, bay platforms, etc., where the anodes are placed in the
mud zone or where high resistivity conditions exist. In many cases, as a
result of the higher driving potential of the Indium activated alloy, fewer
anodes may be required resulting in savings in installation costs. However, the
life of the anodes is reduced by 20% due to the higher current output.
Indium activated alloy hull anodes are also used in ballast tanks and small
oil field brine containing vessels.
Background: Galvanic
Anode Cathodic Protection System
The galvanic system uses
the natural difference in potential between metals to cause a direct electrical
current from an anode through the soil or water to the structure being
protected. Brance-Krachy Co., Inc. has provided industry with quality cathodic
protection equipment for over 65 years.
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