A highly saline atmosphere, extremes of temperature and severe mechanical stress creates specific challenges for those needing to protect their offshore structures from corrosion. Failing to adequately guard against these harmful effects will cost dearly in terms of shortened asset life, increased maintenance costs and more downtime.
Hempel, a world leading coatings supplier, has developed a revolutionary technology called Avantguard. A zinc-rich epoxy coating that exhibits the strength of a traditional epoxy alongside unrivalled anti-corrosion properties.
It does this by combining the ingredients used in traditional zinc epoxies with two new elements – hollow glass spheres and a proprietary activator. This makes the zinc much more effective in altering the electro-chemical reaction between salt, water and oxygen that allows the zinc particles to rust instead of the underlying steel structure. By enhancing the performance of zinc in this way – known as the galvanic effect – Avantguard is able to outperform conventional zinc epoxies. Galvanic protection is just one of three properties delivered by Avantguard to ensure exceptional levels of anti-corrosion. The activated zinc in Avantguard has a high tendency to form insoluble salts throughout the film that makes it less permeable to water penetration creating a barrier effect. This is a significant advantage as traditional zinc epoxies generally exhibit a low level of water resistance.
Simultaneously, the insoluble salts act as environmental scavengers and react with the chloride ions to reduce the movement of corrosive elements through the coating. This delays the corrosion process as the chloride ions are trapped within the coating and prevented from reaching the steel surface. This inhibitor effect is the third type of protection offered by Avantguard.
Continued exposure over extended periods often cause micro-cracks in the paint, which will eventually lead to real cracks and corrosion. The hollow glass spheres within Avantguard absorb most of the stress from the initial cracks and prevents them from worsening. The sub-products formed during the zinc activation process will then occupy the micro-crack and stop it from developing into something more serious. This significantly reduces rust creep helping to ensure the coating retains its anti-corrosive properties for much longer.