Ballast Tank Pitting Rebuild

The challenge

A ballast tank sits under constant seawater immersion, alternately flooded and emptied, and that cycle drives deep, localized pitting into the steel. As the pits advance, the wall loses thickness at scattered points across the plate and the internals, and the corrosion keeps concentrating wherever bare steel is exposed. Left untreated, the pitting perforates the plate and the tank can no longer hold ballast or keep the vessel trimmed safely. The owner needed the steel protected and the pitting arrested without cutting out and replacing plate, which means hot work that is hard to justify inside a confined ballast tank.

Our approach

We start by cleaning the tank internals back to clean, profiled steel so the repair bonds and the corrosion has nowhere left to sit. We cold-fill the pits with a Belzona 1000 Series composite, bringing the scattered metal loss back to a flush, sound surface with no welding and no heat in the tank. Once the substrate is solid and shaped, we apply a 5000 Series immersion-grade lining over the full surface, sealing the cold-filled pits and the surrounding steel under one continuous barrier keyed to seawater service. The work stays cold and confined-space friendly from start to finish.

1. Assess and mapWe enter the tank, map where the pitting is deepest, and confirm seawater immersion service so the lining is keyed correctly.
2. Surface preparationWe clean and abrasive blast the internals to a profiled surface so the cold-fill composite and the lining both bond to bare steel.
3. Cold-fill the pittingWe fill the pits with a 1000 Series composite, bringing the scattered metal loss flush with no welding and no heat in the tank.
4. Apply immersion liningWe apply a 5000 Series immersion-grade lining across the full surface as one continuous barrier over the steel and the filled pits.
5. Inspect and return to serviceWe check the lining for continuity and hand the tank back ready to take ballast again.