The steel secondary containment bund had several perforations in its structure. These appeared to be where near by lawn cutting operations had caused flints and stones to impact the existing coatings, exposing the steel substrate and thus allowing it to corrode.
We proposed a hybrid protective coating solution that both resolves the corrosion that was present as well as bridging the perforations in the structure and strengthening the bund.
Initially all loose and unsound existing protective coatings were removed from the bund using needle guns and tungsten carbide scrapers. The exposed steel was prepared to ST2 as per ISO8501-1. All existing firmly adhered existing coatings were feather edged and thoroughly abraded to raise a surface profile to ensure adhesion of the new protective coatings.
Preparing the surfaces
Following preparation all surfaces were thoroughly vacuumed clean and a soluble salt test conducted due to concerns about potential chemical salt contamination from the contents within the bund. If present soluble salts will draw moisture through a coating film due to their hygroscopic action, leading to premature protective coating failure.
Priming with Corroless EPF Rus Stabalising Epoxy Primer
A primer coat of Corroless EPF rust stabilsing epoxy primer was then applied by brush and roller to a thickness of 200 microns dry film thickness. Corroless EPF contains a mined pigment that passivates any corrosion present, preventing further corrosion form occurring. In addition to this it contains self-leafing glass flake which laminate within the coating to provide a more tortuous route for oxygen and moisture to reach the substrate.
Following priming 3mm thick stainless steel plates which had been manufactured off site and grit blasted to raise sufficient profile for adhesion were bonded to the bund structure using a thixotropic epoxy adhesive. This both bridged the perforations in the bund structure and also served to strengthen any surrounding areas of weakness.
Coating with a UV Stable Polyurethane Coating
Finally the stainless steel plates were coated with a UV stable polyurethane coating to provide an aesthetically pleasing finish.