Anti corrosion measures for Offshore & Structural Steel Plate

Metal steel in the complex marine environment is very vulnerable to corrosion from the impact of sea water, corrosion of marine microorganisms. In particular, once metal steel contacts with substances such as water vapor in seawater, the chemical reaction between them will break the protective layer and coating of metal surface, causing greater corrosion to metal steel structures.

The marine corrosion environment is generally divided into five zones: tidal range zone, marine atmosphere zone, seawater immersion zone, spray splash zone and seabed mud zone. The corrosion types of metal steel structures mainly include atmospheric corrosion, galvanic corrosion, crevice corrosion and stress corrosion.

Protective measures:

1. Electrochemical protection. According to the principle of electrochemical corrosion, when the metal electrolyte dissolution corrosion system is cathodic polarized, the potential of the metal steel will move negatively, which will reduce the potential and reaction speed after the metal anodic oxidation reaction. There are two electrochemical (cathodic) protection methods: impressed current cathodic protection and sacrificial anode cathodic protection.

2. Anticorrosive paint shall be used. Marine anti-corrosion coatings mainly include marine steel structure anti-corrosion coatings and non steel structure anti-corrosion coatings. Anticorrosive coatings for offshore structural steel mainly include offshore bridge coatings, wharf steel coatings, ship coatings, container coatings, oil pipelines, etc. Marine anti-corrosion coatings for non steel structures mainly include anti-corrosion coatings for marine concrete structures and other anti-corrosion coatings.

3. Antifouling paint. Antifouling coating can effectively prevent the adhesion of microorganisms.

4. Corrosion resistant materials. The corrosion resistance shall be fully considered when designing the steel structure. Corrosion resistant materials used in the sea include seawater corrosion resistant steel, corrosion resistant steel bars, duplex stainless steel, etc.