Cathodic Protection

The process of degradation and destruction of metal or metal objects under the influence of chemical, electrochemical, biochemical agents in environment is the corrosion. Degradation process starts at the metal surface and spreads the mass of material. In time this process can destroy the parts or subassemblies. The causes of these unwanted changes, of transformation of metals in their compounds (oxides, carbonates, sulfates, hydroxides, etc..) are chemical or electrochemical reactions that occur on metal surface. These changes are possible because metals tends to return al initial state who is found in nature. In terms of thermodynamic metal- corrosion agent systems are less stable than resulting compounds from their interaction.From quantitative perspective the biggest damage is caused by the atmospheric air, groundwater, water pipeline, gas etc. thus , iron rusts, lose its glow silver, aluminum oxidizes (forming a very thin layer of oxide) which prevents future reactions, zinc and lead lose their luster. Except noble metals , all other metals are unstable in contact with atmospheric air. The way in which manifests this instability is that how it occurs, depends on the nature of the metal and aggressive environment.

Fig.1 Cathodic protection system

In Fig. 1 presents a system of cathodic protection , that include all the necessary equipment to protect pipes from corrosion.Negative terminal (-) is connected to the pipe which must be protected against corrosion and the positive terminal (+) must be connected to a socket anode which will be connection anodes.Anodes is made through a transfer of electrons from the anode to the cathode and the potential difference meansured by reference electrode must be within the limits of (-1200..-850mv) at any point on the pipeline.In Fig. 2 presents electrical panel for cathodic protection which the following components: Distributor Transformer / rectifier Power switch Remote control unit Lightning protectionPower supply will enter in panel by distributor which can also record current consumption.Transformer / rectifier with unit for setting the output voltage remotely via remote monitoring device. Maximum voltage 50 V continuously adjustable recovered Maximum current 50 A continuously adjustable recovered, filtered.

Transformer, rectifier with socket anode and anodes provide necessary cathodic protection current injection in the pipeline.Remote control unit must be equipped with inputs and outputs through which the controller take over information from sensors in the process, this information is processes by controller and sends it through (GSM, Radio, etc.) computer to display these dates, takes data from the computer and transmit them to equipment to maintaining all process parameters in optimal conditions.

Fig.2 Electrical panel for cathodic protection