Causes of Corrosion in Steel Structures in Coastal Areas: Key Issues in Corrosion Prevention for Power Plants and Industrial Buildings (II)

Given the causes of corrosion in steel structures discussed in “Corrosion of Steel Structures in Coastal Areas (I),” what preventive measures can we take?

1. Preventive Measures

(1) Appropriate Material Selection

During the initial construction phase of power plants in coastal regions, steel materials with excellent corrosion resistance should be selected based on environmental characteristics. For example, weathering steel is an excellent choice; through the addition of specific alloying elements, it naturally forms a dense oxide layer in the atmosphere, effectively resisting corrosion. Additionally, for critical components or areas prone to severe corrosion, the use of stainless steel should be considered.

(2) Optimizing Surface Treatment

1) Thorough Rust Removal

Before fabricating and installing steel structures, appropriate rust removal methods—such as sandblasting or shot blasting—should be employed to thoroughly remove rust and scale from the surface. This ensures compliance with specified rust removal grade standards and lays a solid foundation for the subsequent application of protective coatings.

2) Surface Pretreatment

After rust removal is complete, the steel structure surface should undergo appropriate pretreatment, such as phosphating or passivation, to further enhance the surface’s reactivity and corrosion resistance, thereby improving the adhesion between the protective coating and the substrate.

(3) Application of Protective Coatings

1) Selecting Appropriate Coatings

Based on the characteristics of the coastal environment, select a protective coating system with high weather resistance, water resistance, and salt spray resistance. Common combinations include epoxy zinc-rich primers and polyurethane topcoats. The zinc powder in the epoxy zinc-rich primer provides cathodic protection, while the polyurethane topcoat offers excellent weather resistance and decorative properties.

2) Standardizing Coating Application

When applying protective coatings, strictly adhere to construction specifications. Ensure uniform coating thickness and avoid missed or thin spots. Additionally, observe drying times between coats and adhesion requirements to guarantee the integrity and effectiveness of the coating system.

(4) Environmental Control and Maintenance

1) Humidity Control

In steel mills or power plants, indoor air humidity can be reduced by installing dehumidification equipment, thereby minimizing the likelihood of moisture condensation on steel structure surfaces.

2) Waste Gas and Slag Treatment

Improve waste gas and slag treatment systems during production to reduce emissions of pollutants such as acidic gases and dust, thereby mitigating their corrosive effects on steel structures.

(5) Strengthening Structural Design

1) Rational Layout

When designing steel structures, coastal environmental factors must be taken into account. Structural components should be arranged rationally to avoid water accumulation and poor ventilation, thereby reducing the time the steel structure is exposed to humid and corrosive environments.

2) Optimization of Connection Design

Optimize the design of connection points in steel structures by adopting reliable connection methods, such as high-strength bolted connections, and implementing appropriate sealing measures to prevent moisture and corrosive substances from entering the joints and causing rust.

(5) Treatment Methods

1) Surface Cleaning

When rust is detected on a steel structure, the first step is to thoroughly clean the affected areas. Use manual rust removal tools or mechanical equipment to completely remove surface rust layers and peeling protective coatings until the bright surface of the steel substrate is exposed.

2) Localized Repair

For areas with minor corrosion, localized repair methods may be used. First, reapply a primer to the cleaned area—such as an epoxy zinc-rich primer compatible with the original protective coating system. Once the primer is dry, apply the corresponding topcoat to restore its protective function.

3) Comprehensive Repair

If the steel structure exhibits severe corrosion over a large area, comprehensive repair is necessary. This may involve a series of operations, including re-rust removal, pretreatment, and the application of protective coatings across the entire steel structure surface, ensuring the structure is restored to a sound protective condition.

4) Structural Reinforcement

While addressing corrosion issues, if it is found that the steel structure has experienced a reduction in strength or deformation due to corrosion, reinforcement measures must also be implemented. This can be achieved by adding support members or replacing damaged components to ensure the structural safety of the steel structures.

2. Summary

The issue of corrosion in steel structures of industrial buildings within power plants in coastal regions is a matter that requires high priority. Through an in-depth analysis of the causes of corrosion, we recognize the importance and necessity of inspection and assessment. Only through regular, professional inspections and assessments can the condition of steel structures be accurately assessed, potential issues be identified in a timely manner, and a basis be provided for implementing effective preventive and remedial measures. At the same time, only by combining reasonable preventive measures with targeted treatment methods can the safety and service life of steel structures be effectively guaranteed, thereby ensuring the continuous operation of normal production activities at steel mills and power plants.