16 August 2023

Passivation and conservation of drinking water tanks

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May 2022

Location project:

Navantia Shipyard Puerto Real, Cadiz


Fugro Marine Services


Fugro Discovery


nC Corrosion Passivator - Primer WET, nC Protect 4400 Surface Sealant FG


Degrease, remove loose paint by high pressure wash

Application method:

Brush and roller

Fugro has applied nC Marine’s corrosion passivation and sealing to ballast water tanks and potable water tanks on numerous vessels. The biggest advantages are seen as the short pre-treatment time, the fast application time, the above-average longevity of the solution and the minimal contamination and dirt runoff that the solution entails.

It was jointly decided to clean all drinking water tanks by high-pressure washing (200 to 500 bar). This removes all dirt and grease. All poorly adhering paint is also removed with this. It also removes loose rust. This avoids the technically unnecessary, costly and polluting removal of all well adhering paint.

After high-pressure washing, corrosion passivation can be started immediately. Corrosion passivation using nC® Corrosion Passivator – Primer WET must be performed on a wet surface. Through spot repair corrosion passivation takes place on all corroded spots on the drinking water tanks.

After corrosion passivation, the spots are sealed with nC® Protect 4400 Foodgrade Sealant to prevent new corrosion from becoming active. This seal chemically bonds into the passivated metal and has a tremendously long life of more than 15 years.

Benefits passivation:

  • No time wasted blasting and cleaning tanks.
  • No blasting waste saves huge costs.
  • No pollution on board from blasting.
  • Carefully chipping away rust or sanding away rust not necessary, saves days of work.
  • Corrosion passivation at rust prone areas prevents recurring corrosion.

Benefits sealing:

  • Completely waterproof, the sealed areas will not re- or further rust.
  • Paint on the tank remains colorfast due to protection against chlorine and salt influence.
  • Coating on tank surfaces is protected from chemical attack.

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