Furnace Stack High-Temperature Coating

The challenge

A furnace stack corrodes under operating heat, where the hot steel and the flue conditions drive surface attack that thins the shell over time. The metal loss spreads across the stack and weakens the structure that carries the exhaust, and if it is left to run it can force an unplanned outage. The problem is that the unit could not be cooled and shut down for a conventional repair, so any protection had to go on while the stack stayed hot and in service.

Our approach

We treat the stack in place at operating heat rather than waiting for a shutdown that the plant could not give us. First we prepare the hot surface so the coating has clean, sound metal to bond to. Then we apply a Belzona 5000 Series high-temperature coating that is formulated to be put on and cured on a hot substrate, sealing the steel against the corrosion that was thinning it. Where the surface had lost metal, we bring it back with a compatible repair before coating. The crew works the stack in stages so the unit keeps running through the job.

1. Assess and mapWe inspect the hot stack to map the corrosion and metal loss and confirm the operating conditions so the right high-temperature system is selected.
2. Prepare the hot surfaceWe clean and profile the stack surface at operating heat so the coating bonds to sound metal.
3. Rebuild lost metalWe bring thinned and corroded areas back to profile with a compatible repair before the coating goes on.
4. Apply the high-temperature coatingWe apply a Belzona 5000 Series coating formulated for application and cure on a hot substrate, sealing the steel against further attack.
5. Cure and return to serviceWe confirm the coating has cured on the hot surface and hand the stack back without any interruption to operation.