Since 1982, there has been a move to Thermal Sprayed Aluminum (TSA) coating in the “splash zone” of offshore structures.  Our experience indicates that an experience applicator, good surface preparation and quality of wire combined to achieve required thickness and apply the sealer to seal the entire surface.

Corrosion protection of large structures such us wind turbines or offshore platforms operating in corrosive seawater environment is usually provided by cathodic protection (CP) and/or protective coatings. However those methods have some limitations. Organic coatings without CP can provide protection to steel substrate only when they remain intact whereas sacrificial anodes can considerably increase the overall mass of the protected structure and have to be replaced periodically. Moreover sacrificial anodes are only effective under submerged conditions and don’t protect the structure under alternating wetting and drying condition so-called “splash zone” which is particularly corrosive environment due to constant splashing of highly aerated seawater UV radiation and increased concentration of seawater constituents during drying. Furthermore confined volume of electrolyte easy access to oxygen and atmospheric pollutant deposited on the metals’ surface lead to more severe corrosion in this region than in the submerged zone.An alternative corrosion mitigation method is application of thermally sprayed metallic coatings such as thermally sprayed aluminium (TSA). TSA affords long-term and maintenance-free protection to steel substrate in two ways. Firstly when intact it acts as a barrier to the corrosive environment and secondly it provides sacrificial protection by working as an evenly distributed anode which preserves steel in case of a damage of a coating. Moreover large operating temperature range high resistance to mechanical damage and low corrosion rate in ocean water make it a perfect corrosion prevention method for offshore applications.One of the characteristic features of thermally sprayed coatings is porosity which is filled with corrosion products when the corrosion progresses. To delay the self-corrosion of the protective coating application of sealers is recommended.In this work the behaviour of several arc-sprayed metal coatings is investigated under full artificial seawater (ASTM D1141) immersion and compared with simulated splash zone conditions under droplets of artificial seawater. Effectiveness of TSA coatings is evaluated using electrochemical techniques and corrosion products are examined. The effect of novel sealers containing nanomaterials is also assessed.

Splash and immersion zones on offshore installations are areas that are exposed to extremely aggressive environments due to the effects of sea water, tides, wind, waves, and/or ultraviolet radiation.  Various certifications such as NORSOK(1) exist to help guide customers select a coating based on its corrosion resistance performance. Despite the necessity of these standards, it is helpful to understand that other properties such as substrate surface and cure conditions can greatly effect performance of the coatings. In this paper, we will compare adhesion of two coatings to different substrate surface conditions while both coatings will be cured in two different environments. Our goal is to investigate the effect of curing environment of coatings on adhesion to the substrate.