Protecting buried pipelines from corrosion is easily achieved by the use of two commonly applied protection methods:
1. External coating
2. Cathodic protection
These two methods are complementary and should be used in conjunction with the other.
Cathodic protection prevents corrosion at those defects by applying DC current from an external source, forcing the pipeline to become cathode. Application of sufficient DC current to the pipeline will prevent any corrosion from occurring. The two general types of cathodic protection systems are sacrificial and impressed current.
There are three basic approaches to cathodically protect buried pipelines using impressed current anodes:
1. One method is the deep anode in which high current capacity anodes are installed from the structure in a deep hole drilled vertically 150+ feet deep;
2. Another method is to use a shallow ground bed anode design where many smaller capacity ground bed anodes are spaced near the intended structures;
3. The third method is to place a linear anode parallel to and in close proximity to the pipeline to be protected discharging current continuously along its length.
