The Corrosion of Underground Metallic Constructions by Soil
Corrosion is the deterioration of a material over time due to exposure to various environments, including the soil. This can be an issue for underground metallic constructions, as certain soils can cause an accelerated rate of corrosion. Corrosion of these types of constructions can be very costly and time consuming to repair, so it is important to understand the processes that cause corrosion in soils and how to mitigate the effects.
This paper will discuss the various factors that can lead to corrosion of underground metallic constructions, and provide some strategies for controlling it. It will begin by describing the different types of corrosion seen in soils and the effects each has on metal constructions. It will then discuss the factors that contribute to corrosion, including chemical and electrical properties, and discuss how to control these factors. Finally, the paper will discuss how to prevent corrosion and make sure it does not occur in the first place.
There are three main types of corrosion that can occur in underground metallic constructions exposed to soil: uniform, localized and pitting corrosion. Uniform corrosion is a general, widespread and uniform dissolution of the material, while localized corrosion is a specific reactive site or area of the material which experiences a higher rate of corrosion than the surrounding area. Pitting corrosion is a form of localized corrosion which forms small holes, or pits, in the material. Of these three types, pitting corrosion is the most difficult to detect, as it often only has a small surface area.
The factors that contribute to corrosion in soils are primarily related to the chemical and electrical properties of the soils. Chemical properties of the soil can influence the corrosion rate, as certain chemicals can act as either electrolytes (which promote corrosion) or inhibitors (which protect against corrosion). Electrical properties, like pH, temperature, and soil moisture, can also have an effect, as higher levels of electrolytes tend to increase the chances of corrosion.
In order to control the factors that contribute to corrosion, it is important to understand the composition of the soil and its electrical and chemical properties. This can help to identify which chemicals may be present and how to mitigate them. One method of controlling the corrosion rate is to use cathodic protection, where an external current is passed through the construction to provide an electron flow away from the structure, which helps to reduce the rate of corrosion. Other strategies include installing proper drainage and controlling the moisture content of the soil.
In order to prevent corrosion, it is important to make sure that the soil composition is regularly monitored to ensure that the right chemical balance is maintained. It is also important to ensure that any metallic constructions are properly sealed against moisture and properly protected from the environment. It is also worthwhile to use coatings and protective paints to provide a further layer of protection from corrosion.
In conclusion, corrosion of underground metallic constructions due to exposure to soil is a serious issue, as it can be costly and time consuming to repair. By understanding the factors that contribute to corrosion and using appropriate strategies to control them, it is possible to minimize the risk of corrosion and ensure that the construction remains safe and durable for many years to come. By regularly monitoring the soil composition and using protective measures such as coatings, paints and cathodic protection, it is possible to keep corrosion at bay and prevent further damage to the construction.
