CATHODIC CORROSION PROTECTION
CCP (Cathodic Corrosion Protection) as an active protection method attacks corrosion at it’s roots. It is based on the connection between the potential of steel and the corrosion rate. Through installation of a negative protection current the electrochemical potential of the pipeline is brought to a stable passive state and the corrosion process is stopped.
There are two ways for creating an active corrosion protection system for earthburried pipelines:
- Cathodic protection with impressed current
- Cathodic protection with galvanic anodes.
V&C offers both methods, however, we prefer working with an impressed current protection system for earthburried structures.
Cathodic Protection with an Impressed Current Protection System
An impressed current system uses current which is produced by a rectifier and transmitted by foreign current anodes to the earthburried object to be protected. The advantage of this method lies primarily in the possibility that the output voltage can be regulated depending on the soil resistance and the protecting current requirements of the pipeline. Furthermore cathodic corrosion protection with an impressed current system enables automatic recording of the state of the pipeline and thereby possible irregularities can be immediately recognized and fixed. Depending on the local surrounding conditions there are primarily FeSi anodes used, either single or pre-finished as canister anode with backfill.
Cathodic Protection with a Galvanic Anode System
For smaller objects or those where a power supply with rectifier is difficult (e.g. in less conductive grounds) cathodic protection with galvanic anodes is used. The method is based on the difference between the anode material and the object to be protected. As the anode material is not as precious as the metal of the pipeline, current flows automatically from the anode to the pipeline because of the voltage gradient. The required number and size of anodes depend on the size of the object to be protected, the specific soil resistance and the planned term of protection.
The rectifiers of V&C are custom-build and in conformity to international norms and safety standards. They range from a simple, manually adjustable protection rectifier up to a fully automatic regulating rectifier station with remote control for the monitoring of several or complex objects.
Maintenance and Monitoring
A complete monitoring system consists of reference electrodes, measuring devices, measuring points or a wireless remote data transmission system. V&C offers the maintenance of corrosion protection systems with wireless data transmission and remote recording of the data. The data is transferred via GSM network and can then be evaluated comfortably in the office. In this way a permanent monitoring of the protection plants is guaranteed and possible failures can be removed immediately. In addition V&C has a well-skilled and experienced staff team who can carry out commissioning and maintenance measurements on site.