Impressed current cathodic protection

In engineering, the commonly used reference electrodes are copper/saturated copper sulfate, silver/silver halide and zinc reference electrodes, etc., these reference electrodes have their own characteristics, combined for different occasions.

Auxiliary anode

The role of the auxiliary anode is to transfer the DC current output from the DC power supply from the medium to the metal structure to be protected. [1]

The test of pile

The test pile is a kind of auxiliary equipment specially used for the cathodic protection of pipeline with potential probe head to test the protected pipeline. Compared with other power supply types of impressed current systems, the rectifier is economical and simple to operate. [1]

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There are three kinds of potentiostat widely used in engineering: SCR potentiostat, magnetic saturation potentiostat and transistor potentiostat. [1]

System composition

The impressed current cathodic protection system consists of the following sections: auxiliary anode, test pile, DC power supply, auxiliary materials, reference electrode and conductor. [1]

Any power source capable of producing direct current can be used as a power source for an impressed current cathodic protection system. The types of power supply used in the impressed current cathodic protection system are: [2] rectifier, potentiostat; Solar cell; The generator; Wind turbine; Hot battery. Many materials can be used as auxiliary anodes, such as scrap steel, graphite, lead-silver alloy, high-silicon cast iron, platinum-coated titanium, platinum-coated niobium, and mixed metal oxide electrodes.

The output voltage of the potentiostat is limited within 50V. When the project needs higher output voltage, it is necessary to take protective measures for the anode ground bed. These materials have their own characteristics and are used in different situations. SCR potentiostat has large power and small volume, but its overload capacity is not strong. [1]

Reference electrode

The reference electrode has two functions: on the one hand, it is used to measure the potential of the protected structure and monitor the protection effect; On the other hand, the control signal is provided for the automatically controlled potentiostat to adjust the output current, so that the structure is always in a good state of protection. [1]

Dc power supply

In an impressed current cathodic protection system, an uninterrupted DC power supply is required to provide the protection current. To the protected metal, the structure potential of the protected metal is lower than the surrounding environment to protect.

The basic requirements of the power supply of impressed current cathodic protection system are: constant output potential, constant voltage, constant current; Synchronous on-off function; Remote data transmission and remote control. Generally, when the working condition of the structure to be protected (such as the immersed area, water quality, etc.) is basically unchanged or changes very little, you can use the manually controlled rectifier; But when the working condition of the structure is often changing, the potentiostat should be used automatically to make the potential of the structure always in the best protection range. Transistor potentiostat output is stable, no noise, high control accuracy, but the circuit is more complex. In addition, in order to make the anode output protection current more average, to avoid the structure around the anode produced over protection, sometimes near the anode also must be coated with anode shielding layer. Two kinds of rectifier and potentiostat are widely used. Magnetic saturation potentiostat fastening durable, overload capacity is strong, but the volume is relatively large, processing technology is more complex. [1]

Auxiliary materials

Auxiliary materials include insulation joints, grounding batteries, thermite welding, repair pieces, hot melt adhesive, etc. Mainly used for the detection of cathodic protection parameters, is an essential device in pipeline management and maintenance, according to the test function along the layout.