Over many years of parking at Sydney Airport Domestic 1 the author has watched rust steadily taking over..
Will there be a recoat before it is too late?
What is rust?
Rust is another name for iron oxide, which occurs when iron or an alloy
that contains iron, like steel, is exposed to oxygen and moisture for a
long period of time. Over time, the oxygen combines with the metal at an
atomic level, forming a new compound called an oxide
and weakening the bonds of the metal itself.
Left: This load bearing pillar in Sydney Domestic is badly eroded.
Time to take action.
What triggers the degradation?
The salt blown in by the proximity to the bay and the prevailing easterly wind greatly accelerates the rust process. Pooling water doesn’t help, and is especially evident on the closed flanges. The initial coating system can’t have been too sound either for such degradation to take place. Along with lack of preventative maintenance.
What should be done?
A remedial program should be immediately put in place. We suggest this would involve;
- Removal and replacement (under engineer supervision) of holding down nuts, preferably if safe to do so with cleaning and rust removal in between the two operations.
- Thorough cleaning to remove all salt contamination, preferably by high pressure water blasting.
- Spot blast rust areas to Class 2.5.
- Abrade sound existing coating
- Apply 100 microns Zinc Rich epoxy to all bare steel.
- Apply 250 microns High Build epoxy to primed areas and sound existing coating.
- Apply 60 microns Fluoropolymer to all primed areas.
A&I Coatings has all these products available in both solvent borne and water borne systems, and sells Australia wide through Dulux for steel coatings. They sell under the Duration brandname.
Alternatively
It may not be possible to achieve the level of cleanliness needed for a zinc rich primer.
The author about 12 years ago cleaned an area of badly rusted handrail (uninvited), and applied A&I Coatings E1980 Rust Convertor. This product is not a typical rust convertor, being based on an expensive European resin.
This area was left without high build intermediate coat epoxy, or topcoat, and was observed for about 6 years.
The rust convertor performed amazingly well. This may be the way to go. That is;
- Thorough salt removal
- Thorough hand tool cleaning
- Application of Envirothane 1980 Rust Convertor
- Application of high build epoxy
- Application of fluoropolymer topcoat
Again, all possible in waterborne, with minimal disruption to the carpark.
Please feel free to email us on Helpdesk@aicoatings.com or get in touch with us below with your details if you would like more info on these products. our Team will be glad to assist!
Want more info on our range of Steel Protection systems? look at some of our other blogs…
