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.

The Belzona approach

Work starts with cleaning the tank internals back to clean, profiled steel so the repair bonds and the corrosion has nowhere left to sit. A Belzona 1000 Series composite cold-fills the pits, 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, a 5000 Series immersion-grade lining goes 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 mapThe tank is entered, the deepest pitting mapped, and seawater immersion service confirmed so the lining is keyed correctly.
2. Surface preparationThe internals are cleaned and abrasive blasted to a profiled surface so the cold-fill composite and the lining both bond to bare steel.
3. Cold-fill the pittingA 1000 Series composite fills the pits, bringing the scattered metal loss flush with no welding and no heat in the tank.
4. Apply immersion liningA 5000 Series immersion-grade lining goes across the full surface as one continuous barrier over the steel and the filled pits.
5. Inspect and return to serviceThe lining is checked for continuity, and the tank is ready to take ballast again.