Buried pipe, external corrosion

Corrosion occurs either internally or externally. External corrosion can occur on both surface and buried portions of the pipeline. Aboveground, piping is protected by painting or specialized coatings. Below-groimd, piping is protected by specialized coatings and... 

External corrosion system that includes corrosion problems such as those occurring in the soil surrounding the buried pipe, the coating, the cathodic protection system,. .. 

Examples of the sacrificial-anode method include the use of zinc, magnesium, or aluminum as anodes in electrical contact with the metal to be protected. These may be anodes buried in the ground for protection of underground pipe lines or attachments to the surfaces of equipment such as condenser water boxes or on ship hulls. The current required is generated in this method by corrosion of the sacrificial-anode material. In the case of the impressed emf, the direct current is provided by external sources and is passed through the system by use of essentially nonsacrificial anodes such as carbon, noncor-rodible alloys, or platinum buried in the ground or suspended in the electrolyte in the case of aqueous systems. 

Resistance to corrosion due to external and internal environment, including compatibility with different materials external threats such as soils in which the pipe is buried, groundwater, and so forth, and internal factors such as corrosion inhibition and other chemical treatments... 

Offshore platforms are, in essence, similar to buried pipelines because in both, external and internal surfaces are exposed to corroding environments in buried pipelines the external surface of the pipe is exposed to the soil (which is a corrosive environment), and its internal surface is under the corrosive impact of the fluid that is going through, either water, oil or the like. In case of offshore platforms, the whole immersed stmcture is exposed to seawater (a corrosive medium), and the internal surfaces of the systems such as seawater injection systems or oil storage facilities can be considered locations at which corrosion is occurring internally. 

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