Pipeline Cathodic Protection against pipelines corrosion

Steel pipelines are used in many areas of the world and in many businesses. They may be located above ground, below ground, and under water. Whether they are used for transporting oil or other fuels or for transporting water from one location to another, they are an important part of many businesses and even can be very important to countries all over the world. Because of their importance, many pipelines use a pipeline cathodic protection system.

Over time, steel can corrode, especially if the steel pipeline is submerged under water or is carrying water. The free electrons in the steel itself interact with the oxygen that is available in the water and create hydroxyl ions, which then may recombine with the oxygen in the water to create what is called ferrous hydroxide. Another term for this is corrosion. As you can imagine, problems can occur when areas of important pipelines begin to corrode. If the corrosion is not stopped or at least impeded to some degree, areas of pipeline will constantly need replacement in order to prevent problems from occurring when the contents of the pipeline leak out through the corroded areas of pipeline.

Pipeline cathodic protection was invented as a means to stop or slow this corrosion and was actually visualized by Sir Humphry Davy in 1824. It took about one hundred years before this method of protecting steel from corrosion became widely used. The basic idea of a cathodic protection system is that the pipeline is cathodically protected through the use of an electrical current. This can be done with either galvanic anodes or impressed current. Because the current supplies a steady stream of free electrons along the pipeline, the hydroxyl ions do not recombine with the oxygen from the water, and corrosion is avoided or minimized.

The steel in the pipelines have areas that are both cathodic and anodic. The anodic areas are the places that corrode, so as part of galvanic or anodic pipeline cathodic protection, sacrificial anodes are attached or combined with the pipeline so that the pipeline itself does not corrode. Such sacrificial anodes can be made of a variety of materials, depending on the material that the pipeline is to be made from. Often, aluminum and magnesium alloys are used. This basically means that the entire pipe becomes a cathode and the sacrificial anode corrodes. There is no outside power source necessary for this type of protection because the materials themselves cause the current to flow naturally. The sacrificial anode will eventually become totally corroded and will need replacement as the pipeline structure ages.

Impressed current pipeline cathodic protection (ICCP) systems are generally used in larger structures because the galvanic anodes are not capable of producing enough current to provide sufficient cathodic protection. The impressed current requires a DC power source. Usually, other power sources are used and converted to the necessary DC. A variety of materials may be used as anodes for the impressed current

Pipeline cathodic protection can be applied to new pipelines, systems that have been around for a while that need additional protection, and even in hot spots where corrosion is becoming a problem. This means that the life of existing pipeline systems can be extended and problems avoided through the use of this technology. A thinner-walled pipe may be used if it has been sufficiently protected, which can save quite a bit of money in the production of the pipeline itself. As you can see, there are many advantages to using pipeline cathodic protection.

When a power source is being used, a pipeline cathodic protection station is often set up to monitor the output of the current and to keep tabs on how the system is working. The cathodic protection station may have one or more channels and may be equipped with alarm systems. Volts and amps may be recorded and the values compared to the tested settings. Modern technology has allowed such stations to be controlled via mobile phones so that no matter where you are, you can keep tabs on what is happening at the station and even make adjustments to the amount of current being supplied. You can start the CPU, set your parameters for monitoring, select the desired mode of operation and required settings and even change the control program settings. You can also receive emergency messages from the control system.

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