Hot Dip Galvanising and GALVACOAT Paint System (paint for galvanised steel) combine successfully
When it came to designing Newry’s Street Market back in 2001, the challenge was to re-create ‘old world’ charm and character. This was achieved through the use of Victorian style, steel columns that support the attractive timber paneled roof.
As is often the case, functionality and aesthetics needed to combine in order to achieve a successful outcome. Nicolas O’ Dwyer Consulting Engineers had a requirement that the steelwork would meet certain criteria:
- It should be adequately protected from corrosion.
- It should be maintenance free for the maximum period achievable.
- It should provide an aesthetic impression in keeping with the overall design concept.
The key to corrosion protection was Hot Dip Galvanising. It has great advantages over other systems.
Firstly, the dipping process ensures that all the steelwork is protected inside and out.
Secondly, the sacrificial action of the galvanised coating ensures that any local damage caused in the future would not spread as sideways creep of rust is prevented.
The other great advantage of Hot Dip Galvanising is its longevity. The corrosion rate of zinc is so slow that 80-100 years life to first maintenance is quite achievable in an environment such as this.
Finally, to finish off the steelwork a topcoat of paint was required to provide the aesthetic appeal that was appropriate. The difficulty has always been to find a quality paint that would adhere well to the galvanised surface while also providing a tough, long lasting surface that would stand up to daily abuse and natural weather conditions.
The answer to this problem was a product called Galvacoat. This is quite simply a top quality, 2-pack polyurethane paint with unique binding agents that allow it to bond successfully with galvanised surfaces – immediately after galvanising.
Galvacoat is readily available in all Ral & BS colours and fills a void in the market that specifiers have struggled with for years.
As this was one of the first major projects where this system was used we thought it would be useful to carry out a study of its performance over the two and a half years since it was erected. It was examined to see if good adhesion had been achieved or if the colour/appearance had deteriorated. The results were excellent from both perspectives.
These pictures clearly demonstrate how well the appearance has been retained and that no peeling is apparent over the entire 80 tonnes of steel.
Consulting Engineer: Nicholas O'Dwyer
Steel Fabricator: Terence McCormack Ltd.