Two technologies of cathodic protection

Two technologies of cathodic protection

There are two kinds of cathodic protection technologies: sacrificial anode cathodic protection and forced current (impressed current) cathodic protection.

1) Sacrificial anode cathodic protection technology

Sacrificial anode cathodic protection technology is to electrically connect a metal or alloy with a potential more negative than that of the metal to be protected with the metal of the cathodic protection material to be protected, and protect other metals by relying on the current generated by the continuous corrosion and dissolution of the metal with a relatively negative potential.

Advantages: A: the one-time investment cost is low, and there is basically no need to pay maintenance costs during operation

B: The utilization rate of protection current is high, and no over protection will be generated

C: For adjacent underground metal

The facility has no interference effect, which is applicable to the plant area, long-distance pipelines without power supply, and small-scale scattered pipeline protection

D: E: the construction technology is simple, and special professional maintenance and management are not required at ordinary times.

Disadvantages: A: low driving potential, narrow protection current regulation range and small protection range

B: The use range is limited by the soil resistivity, that is, the soil resistivity is greater than 50 Ω? Generally, the sacrificial anode protection method should not be used

C: In the area with strong stray current interference, especially under AC interference, the anode performance may be reversed

D: The effective cathodic protection life is limited by the life of sacrificial anode and needs to be replaced regularly

2) Forced current cathodic protection technology

The forced current cathodic protection technology is to connect a DC power supply in series in the circuit, pass the true current to the protected metal with the help of the auxiliary anode, and then turn the protected metal into a cathode for protection.

Advantages: A: high driving voltage, flexible control of cathodic protection current output in a wide range, suitable for protection

A wide range of occasions.

B: It is also applicable to harsh corrosion conditions or high resistivity environment

c: When insoluble or slightly soluble auxiliary anode is selected, long-term cathodic protection can be carried out

D: Each auxiliary anode bed has a large protection range. When the pipeline anticorrosion coating is of good quality, the protection range of a cathodic protection station can reach tens of kilometers

E: Complete cathodic protection can also be achieved for bare or poor quality pipes

Disadvantages: A: the one-time investment cost is high, and the electricity fee needs to be paid during the operation

B: During the operation of cathodic protection system, strict professional maintenance management is required

C: Cannot leave the outside

D: It may cause interference to adjacent underground metal structures