It’s a Little Rusty: How and Where These Common Forms of Corrosion Occur

Rusty and corroded metal wall

Corrosion forms when a metal comes in contact with oxygen or moisture. Other corrosive agents include acid and salt (usually from saltwater). Over time, corrosion can cause the degradation of engineering materials.

Buildings are at a serious risk of disintegration when corrosion occurs. Additionally, oxidization threatens the integrity of tanks, Enviro Care Inc. says. But, corrosion can be prevented even before the construction of the tower by choosing the right materials like metals and protective coating.

Similarly, cathodic protection can be applied. In this method, the engineering material is coated with a metal that is more likely to oxidize, the outer layer then serves as a protective or sacrificial coating.

Preventive measures vary and depend, in part, on the kind of corrosion that occurs.

  • Localized Corrosion: This corrosion occurs on a specific area of the metal and can be either pitting, filiform, or a crevice.
  • Pitting: When this occurs, holes form on the metal. The pits can be narrow and deep, or elliptical and shallow. These tiny cavities can compromise the entire engineering system of a building.
  • Filiform: This occurs under painted or plated surfaces and causes flaws in the coating. Usually, surfaces with quick-dry paints are vulnerable to this kind of corrosion.
  • Crevice: This usually occurs on surfaces where oxygen is limited or not present, including on insulation materials and washers.
  • Galvanic Corrosion: This is also called bi-metallic corrosion because it occurs when a current is self-inducted between two dissimilar materials. One of the metals becomes the anode and the other becomes the cathode. The anode corrodes faster, while the cathode corrodes slower.
  • Flow-Accelerated Corrosion: This occurs when the metal’s protective film experiences dissolution due to fast-flowing liquid. Consequently, the metal under the film starts to deteriorate.

Corrosion is a big problem, especially in the engineering industry. In fact, there is an estimated $2.5 trillion loss due to corrosion. Apart from the financial problems that come with it, oxidization can also pose a serious health risk as it can form on the metal surface of water tanks.