API 571 : 4.3.2 : Atmospheric Corrosion

Marine environments and moist polluted industrial environments are highly corrosive due to the presence of airborne contaminants such as salt, sulfur compounds, and pollutants. These contaminants react with the metal surfaces, leading to the formation of corrosion products. The high humidity and moisture in these environments accelerate the corrosion process, making them particularly severe for atmospheric corrosion. Therefore, the statement "Marine environments and moist polluted industrial environments with airborne contaminants are most severe to atmospheric corrosion" is true.

Bird turds can cause accelerated atmospheric corrosion because they contain high levels of uric acid, which is highly corrosive to metals. When bird droppings come into contact with metal surfaces, the uric acid reacts with the metal, causing it to corrode at a faster rate than normal. This can lead to damage and deterioration of structures or objects exposed to bird droppings over time. Therefore, it is true that bird turds can cause accelerated atmospheric corrosion.

Marine environments are known to be highly corrosive due to the presence of saltwater and various other corrosive agents. The corrosion rate in such environments is typically high, resulting in the degradation of metal structures and equipment. The approximate corrosion rate of 20mpy (mils per year) suggests that metal surfaces in marine environments can experience significant corrosion, leading to potential damage and the need for regular maintenance and corrosion protection measures.

Atmospheric corrosion refers to the corrosion that occurs when metal is exposed to the atmosphere. It is caused by the interaction of the metal with moisture, oxygen, and other corrosive agents present in the air. Corrosion Under Insulation (CUI) is a specific type of atmospheric corrosion that occurs when moisture becomes trapped between insulation material and the metal surface, leading to accelerated corrosion. Galvanic corrosion, on the other hand, occurs when two different metals are in contact with each other in the presence of an electrolyte, causing one metal to corrode faster. Mechanical damage refers to corrosion caused by physical forces such as abrasion or impact, rather than chemical reactions with the environment. Since atmospheric corrosion is the general mechanism at play in this question, the correct answer is None of these.

Bimetallic connections, such as copper to aluminium electrical connections, can experience atmospheric corrosion. This is a process where the metal surfaces react with elements in the air, such as oxygen and moisture, leading to the formation of corrosion products. Over time, this corrosion can weaken the connection, leading to electrical resistance, poor conductivity, and potential failure of the connection. Erosion refers to the wearing away of materials due to mechanical forces, while galvanic corrosion occurs when two dissimilar metals are in contact in the presence of an electrolyte, causing one metal to corrode.