Nick’s recent Scottish travels took him to sites where issues ranged from extreme wind to exposure to corrosive atmosphere, from Inverary, to Fort William; from John O’Groats to Oban, from Orkney to Inverness to name just a few destinations.
Being an island under the general heading of the ‘British Isles’ much land faces sea. The result is much economic activity depends on access to the sea which brings with it wind load challenges and the corrosive impact of salt itself writes Chris Dobson.
A recent tour of UK locations which feature Hart doors showed that five sites were exposed to highly corrosive atmospheres as well as extreme wind. Under these circumstances doors have to withstand wind up to 1250 pascals. It should be noted that Hart is capable to facing global challenges. As an example a block of flats in Hong Kong has Hart doors with no failures in six years.
Returning to the impact of salt from nearby seas, there are problems for industry caused mainly by accelerating corrosion and damaging equipment.
Salt-laden air near coastlines carries chloride ions, which are highly corrosive to metals. When these ions settle on industrial equipment, they can accelerate corrosion by making moisture more conductive, speeding up electrochemical reactions that rust metal.
Further the breakdown of protective oxide layers on metals like steel and stainless steel can lead to pitting and structural weakening. Typically the electrical infrastructure can be damaged with switchgear and transformers degrading faster in coastal environments.
Electricity distribution equipment corrodes more quickly, reducing lifespan and increasing maintenance costs and in general threatening reliability.
Even concrete structures can be affected by chloride ions which penetrate concrete and corrode internal steel reinforcement. To avoid this, protective coatings such as marine‑grade paints can assist, polymer coatings, galvanisation) to isolate metal from salt exposure.
The key message is all main access to buildings should be protected by automatic door systems such as Harts insulated rolling shutter doors manufactured in the UK. As the longest established British manufacturer of high-speed insulated roller shutters, Hart offers a range of reliable custom insulated shutters suited to specific requirements. Hart has a wide selection of lath profiles recommended for temperature control.
After a recent, intensive tour of projects in Scotland, Nick Hart, Hart’s managing director, gives a detailed insight into the issues faced as result of sea salt. “Yes the electrical equipment is one area which is cause for concern in a saline environments but equal consideration should be made to the materials the doors is made from and particularly the effects of galvanic corrosion when two dissimilar metals are in contact with one another, which accelerates the corrosion of one of the components.,” says Nick.
“ We have reviewed the entire design of the doors that are destined to be installed in such an environments and create isolating barriers between the different metals to slow down any potential corrosion, as well as using corrosion resistant materials, i.e. stainless steel and non-metallic materials where possible, special bearings and protective coatings. This approach gives the customer the best door solution for what is a very difficult corrosive environment.”
Wind loading is another important factor. Mr Hart says; “Our approach is based on BSEN12424 details wind-class of doors and how to test them. It categorised wind class from 0 to 5, 5 being the most onerous and the door sample needing to survive a pressure of above 1000Pa + 25%, i.e. over 1250Pa”.
Mr Hart adds; “As we know wind class 5 rating is not adequate for many installations throughout the UK, especially in coastal locations. As a result we designed a new type of roller shutter that is capable of surviving much larger forces and build an 8meter wide test rig and tested door sample to 3000Pa and 4000Pa plus 25%, that is door samples tested to 3750Pa and 5000Pa pressure levels respectively.
“This is a industry first and as a result we have successfully sold Typhoon roller shutters in areas that annually experience extreme wind conditions, which include Hong Kong where we have supplied these doors onto the Hong Kong airport and on high rise buildings up to the 19th floor.”
