Above ground storage tanks display a large surface area that can often be covered in unsightly rust. A long-term coating is needed to reduce maintenance costs as scaffolding and tarping a tank for coating typically costs more than the actual blasting and re-painting costs. Thermal spray zinc (TSZ) duplex coatings have been shown to be highly durable. In a life cycle comparison with paint, the durability of metallic zinc coatings eliminates the repeat burdens of maintenance painting, significantly reducing the total cost of ownership of a structure. Furthermore, zinc coatings have significantly lower life cycle impact in terms of global warming potential, acidification potential, and photo-chemical ozone creation potential, providing a more sustainable corrosion maintenance strategy. A thermal spray zinc duplex coating applied with three aerial work platforms can eliminate the need for scaffolding and tarping and provide an economical and sustainable coating system with a service life typically exceeding 50 years.
Controlling corrosion of steel is expensive. The direct costs of corrosion maintenance are estimated to be over 3% of GDP every year.1 Metallic zinc coatings provide very effective corrosion protection for steel by acting first as a barrier coating, keeping corrosive elements away from the steel, and secondly as a sacrificial anode.2 Should the zinc coating be compromised, accidentally by a scratch or on purpose with a drilled hole, the zinc will provide anodic protection to the exposed steel. Metallic zinc coatings can be pure zinc or zinc-based alloys and will be referred to generically as zinc coatings in the paper. Zinc coatings can be efficiently applied by thermal spraying, which involves projecting particles of semi-molten zinc onto the surface of the steel using compressed air. With thermal sprayed zinc (TSZ) coatings, there is no size limitation to the part to be coated, and the technology is fully portable, allowing easy field applications.
