Résumé : |
A new perimeter security barrier was installed at an electrical power station in the rural, mid-Atlantic U.S. Installed over several weeks in the late fall, the barrier was construted from thin galvanized sheet panels, approximately 6 feet by 8 feet in size, that were formed into a corrugated shape and then shop-coated. The formed shape had horizontally angled bends across the sheet (near the top and bottom) and multiple vent openings.
The primary surface preparation in the shop consisted of a degreasing process using an acidic solution. The galvanized sheet was then powder coated in a fluidized bed process with a low-density polyethylene (LDPE) coating material. Field touch-up was accomplished using an acrylic primer/finish coating.
The following spring, coating failure was first reported in the form of delamination from the galvanized substrate. The failure grew worse as the year progressed, and the facility owner contracted with an independent coating consulting firm to investigate the premature failure. |