Metal or thermal spraying is a technology, which protects and greatly extends the life of a wide variety of products in the most hostile environments and in situations where coatings are vital for longevity. The variety of metallised coatings is vast but can be broken down into two main categories. These include finishing coatings, such as anti-corrosion or decorative coatings, and engineering coatings such as wear resistant and thermal barrier coatings. Metal spraying is carried out in a wide range of anti corrosion and engineering markets, including oil and gas, construction, petrochemical and marine. Corrosion is a major problem for these industries.
Thermal Spraying is not a new process. It has proved itself to be extremely effective in the 90 years of its existence in all manner of applications ranging from coatings in gas turbines to corrosion protection on park benches. As a protective system for structural steelwork it is unsurpassed being the only system, recommended by International and European standards EN ISO 14713 as giving greater than 20 years to first maintenance in very aggressive environments such the marine splash zones.
The range of applications that metallising is used for has mainly developed as a result of the limitations of other available processes. For example, new bridge sections are often sprayed to offer maximum corrosion protection. The ‘I’ beams can
be as much as 40m (120ft) long, 4m (12ft) high and 2m (6ft) wide. Obviously, this is too large for the average hot-dip galvanising tank. The process is also transportable, so structural steelwork can also be sprayed on-site or repaired where on-site welding has removed the galvanising. Other common anti-corrosion application areas are off-shore oil platforms, ships, fences, underground pipes, electric rolled welded (ERW) tube manufacture, multi-void aluminium tube manufacture, LPG cylinders, water / fuel tanks, external and internal steelwork and playground furniture. This is a very short summary of a virtually endless list of applications.
Independent laboratory testing carried out by the American Society for Testing and Materials has verified that Thermal Sprayed Zinc exhibited superior corrosion resistance to that of hot dipped galvanising for iron products when tested in accordance with the various international standards. In summary after 120 hours of exposure to salt spray, the galvanised item exhibited red corrosion. The thermal sprayed zinc sample did not exhibit any signs of corrosion.
Below we have attached details on the lifespan of thermal coatings applied to Bristish and European Standards.