Some of the more commonly used cathodic protection materials are outlined as follows:
The majority of sacrificial anodes used in soils are either magnesium or zinc. Aluminum anodes are not as common, but are available for special applications. The high-potential magnesium anodes vary in size from one (1) pound up to thirty-two (32) pounds and larger if desired. The zinc anodes are also available in various sizes, including the forty (40) pound treater anode. This anode is specifically designed for internal protection of vessels. Aluminum anodes are also used in this application. For soil application, both the zinc and magnesium anodes are supplied with a special backfill to enhance the anode operation.
Impressed Current Anodes:
There are several anodes available in this category. The use of one type as compared to another largely depends on circumstances involved.
i) Cast Iron Anodes:
Presently these anodes are the most widely used impressed current anode in North America. They can operate at current densities up to 2.0 amperes per anode, with an expected minimum life of 10 years.
These anodes can be supplied either as standard or with chromium additions. The standard anodes are somewhat less expensive. However, the chromium added to anodes results in lower consumption rates.
All cast iron anodes come complete with an eight (8) foot lead. The connection to the anode is both mechanically sound and guaranteed waterproof. Various lead lengths can easily be supplied upon request.
ii. Mixed Metal Oxide Anodes:
These anodes are small, lightweight, and can operate at current densities much higher than conventional impressed current anodes (approximately 10 amps/ft2 in soil). In addition, the mixed metal oxide coating on the anodes has an almost negligible consumption rate of less than 1.0 mg/amp-year.
These anodes are becoming more popular due to their high performance and extremely long life.
B. Calcined Petroleum Coke Breeze:
Standard practice is to surround impressed current anodes with clean, calcined petroleum coke breeze with a resistivity not to exceed 50 ohm-centimeters. Also available is Loresco coke breeze, which is primarily used in deep anode applications.
Also available is Loresco coke breeze, which is primarily used in deep anode applications. Interior Corrosion Services can supply all cable demands required for use in cathodic protection installations.
D. Cathodic Protection Rectifiers:
The DC current rectifiers are available in a wide variety of standard sizes and usually one of these standard sizes will closely match the requirements of any given application. The custom aspect is usually applied in the metering, control and protection phases of the specific units.
E. Miscellaneous Materials
In conjunction with the major materials mentioned previously, Interior Corrosion Services is readily able to acquire materials related to the cathodic protection industry. To list all of these here would be impractical however, to put forward some ideas of the scope involved, and some are listed as follows:
- Test Stations
- Thermal Weld Equipment
- Connection and Splicing Materials
- Insulating Unions and Flange Kits