How to improve the corrosion resistance of steel structures in deep sea environments?

Improving the corrosion resistance of steel structures in deep-sea environments requires comprehensive measures from multiple dimensions such as materials, processes, technology and management.

1. Material upgrade and innovation
   Research and development of seawater corrosion-resistant steel
   Develop new alloy steels, such as the corrosion-resistant steel plates for marine building structures developed by Anshan Iron and Steel. Through composition optimization and organizational regulation, the corrosion resistance is increased by more than 3 times compared with traditional steel, and it can adapt to the high salt fog and strong radiation environment of the South China Sea.
   Explore the combination of high-strength steel (such as 1500MPa grade) and low-temperature resistance (zero plastic transition temperature ≤-100℃) to meet the needs of extremely deep sea areas.
   Surface modification technology
   Use metal coatings such as hot-dip galvanizing and thermal spraying aluminum to form a physical isolation layer;
   Develop nano-composite coatings (such as graphene-modified epoxy resin) to improve anti-penetration and self-healing capabilities.
2. Composite anti-corrosion technology system
   Multi-layer mineral fat coating technology
   Developed by the Institute of Oceanology, Chinese Academy of Sciences, it achieves long-term protection through a four-layer structure (mineral fat anti-corrosion paste, anti-corrosion belt, buffer layer, FRP protective cover), can be constructed with water, and is suitable for anti-corrosion in splash zones of new and old structures, with a service life of more than 30 years.
   Coating and cathodic protection synergy
   Organic coatings: epoxy, polyurethane and other coatings provide basic protection, and sandblasting and rust removal are required to ensure adhesion;
   Cathode protection: sacrificial anode method (zinc, aluminum-based alloy) or impressed current method to inhibit local corrosion, especially suitable for full immersion areas.
3. Structural design optimization
   Reduce corrosion hazards
   Avoid structures that are prone to fouling such as gaps and sharp corners, and adopt streamlined design to reduce the attachment of marine organisms;
   Choose welding instead of bolted connections to reduce the risk of electrochemical corrosion.
   Corrosion allowance reserve
   Increase thickness redundancy in key parts (such as the legs of the conductor frame) to extend the service life.
4. Intelligent monitoring and maintenance
   Digital monitoring system
   Integrate fiber grating sensors and AI algorithms to monitor corrosion rate, coating integrity and structural stress in real time, and warn of potential risks.
   Green maintenance technology
   Develop coating materials that can be repaired underwater (such as self-healing polyurethane), and combine robotic operations to reduce maintenance costs.
5. Full life cycle management
   Standardization and certification
   Formulate standards for deep-sea steel (such as corrosion resistance and weldability indicators) to promote international mutual recognition.
   Circular economy model
   Use recyclable steel and combine scrap steel resources to reduce environmental load.
   Summary:
   Deep-sea steel structure corrosion protection needs to focus on the “material-process-monitoring” trinity, combined with multi-layer mineral fat coating, high-performance corrosion-resistant steel and intelligent technology to break through the splash zone protection problem. Future trends include self-healing coatings, bionic corrosion protection (such as imitating marine biological mucus) and full industry chain collaboration to achieve long life, low cost and sustainable development of deep-sea facilities.