What Does Deposit Corrosion Mean?
Deposit corrosion is a type of localized corrosion in which deposits or a collection of material form on a metal surface. This type of corrosion occurs around or under an irregular deposit on metals. The localized corrosion is intense and usually occurs within guarded areas and metals open to corrosives. In general, it occurs at the area where metal comes into contact with other metals, and with with metals to non-metals.
Deposit corrosion is typically related to minute volumes of inactive solution from lap joints, surface deposits, gasket surfaces or crevices that are under rivet heads and bolts.
Deposit corrosion is also known as crevice erosion or under deposit corrosion.
Corrosionpedia Explains Deposit Corrosion
Deposit corrosion is one of the most severe types of corrosion, especially affecting piping systems. It is very localized and aggressive, leading to deep penetration of the metal surface with less corrosion involved in the adjacent areas. Surface deposits are the major reason why corrosion factors and other forms of initiating mechanisms choose individual sites.
In some cases, pitting can be seen throughout the metal surface. The effect is a very rough and irregular profile. Sometimes, the pits can only be seen in certain areas, leaving most of the metal in almost new condition. While fasteners and screws are regarded as the main sources of deposit corrosion problems, it also may occur under barnacles, washers and protective films.
Deposit corrosion can be prevented by:
- Maintaining cleanliness
- Ensuring proper use of protective coatings and sealants
- Use of stainless steel grades that contain molybdenum, like 316 or 316L, which have more resistance to deposit corrosion