Introduction
Various segments of the industry face constant challenges with corrosion, which not only compromises the integrity of structures and equipment but also threatens operational safety and sustainability.
Corrosion is a natural phenomenon that primarily affects metallic materials, causing their degradation and loss of properties, which can compromise the quality, safety, and productivity of industrial assets, leading to financial and environmental losses.
Global Scenario:
Corrosion represents an annual cost of $2.5 trillion worldwide, according to data obtained by the National Association of Corrosion Engineers (NACE).
Nexa Resources points out that approximately 30% of the world’s iron and steel production is lost due to corrosion.
Main Types of Corrosion in Industry
Understanding the causes of each type of corrosion is essential to implementing effective measures to control and prevent damage to assets.
Below are the most common types found in the industry.
Uniform Corrosion: It is the most common type of corrosion, characterized by the uniform loss of material along the surface of the metal. This process can occur slowly but consistently, compromising the structural integrity of the parts.
Pitting Corrosion: In this case, corrosion occurs unevenly, forming pits or irregular spots on the metal surface, where pieces gradually detach from the part.
Pitting Corrosion: It is characterized by the formation of small cavities or “pits” on the metal surface. It can be especially harmful since the depth of the corrosion is usually greater than the diameter of the formed crater, potentially developing rapidly.
Crevice Corrosion: This type of corrosion occurs in areas where there is restricted access to oxygen and water, such as crevices, joints, and interfaces between materials, and is common in welded or bolted structures.
Intergranular Corrosion: Resulting from the degradation of the grain boundaries of the metal, intergranular corrosion can compromise the structural integrity of parts as it weakens the metal structure, potentially leading to failures.
Alveolar Corrosion: Characterized by the formation of small cavities resembling alveoli on the metal surface, it has a rounded bottom and a depth less than its diameter.
Exfoliation Corrosion: It is characterized by the separation of layers within the material, causing the metal to swell, resulting in a loss of thickness and weakening of the structure.
Under Insulation Corrosion: Occurs when corrosion develops under materials used to insulate equipment and pipelines. These materials retain moisture and corrosive substances, creating a conducive environment for damage.
Prevention and Correction Strategies
To mitigate the harmful effects of corrosion, several prevention and correction strategies can be adopted:
Prevention:
- Use of protective coatings such as paints, varnishes, or galvanization.
- Use of corrosion-resistant metal alloys.
- Application of protective layers such as chrome plating or anodization.
- Engineering design that minimizes corrosion points, such as proper drainage and ventilation.
- Use of chemical inhibitors to reduce corrosion rates.
- Implementation of continuous monitoring systems.
Correction:
Corrective action varies depending on the extent and nature of corrosion, the type of affected structure, and the environment.
When the structure is not compromised, common corrective actions include cleaning the area by removing corrosion using mechanical methods such as wire brushes, sanding, or blasting, or chemical methods such as applying chemical solvents and acids to dissolve it. Subsequently, a protective agent like primer or specially formulated corrosion-resistant paint is applied.
Conclusion
It is crucial for companies to implement preventive and corrective measures to combat various types of corrosion. Investing in corrosion protection not only prolongs the lifespan of industrial assets but also ensures safety and operational continuity.
By prioritizing effective asset integrity management, companies strengthen not only their infrastructure but also their reputation and corporate responsibility, demonstrating a firm commitment to people’s safety, operational excellence, and long-term sustainability.
References:
IBRAM (ed.). Corrosion process causes 30% of global iron and steel production to be wasted. 2020. Available at: IBRAM Website.
KOCH G.; VARNEY J.; THOMPSON O.; MORGHISSI M.; GOULD M.; PAYER J. International Measures of Prevention, Application, and Economics of Corrosion Technologies Study. Nace Int. 2016 (2016). Available at: NACE International Report.
