16 August 2023

THQ beams passivation

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August 2019

Location project:

Parking garage Dekamarkt, Wormerveer, Netherlands


Construction company and owner together, the Netherlands


Parking garage Dekamarkt


Corrosion Passivator - Fluid


None, not necessary

Application method:

Floating. Curing time: Not applicable

The parking garage in question was constructed using hollow THQ beams (hat beams). All hat beams are made of galvanized steel, and the individual plates are welded together to form a hat beam. Cross bracing was also welded into the hollow hat beams for reinforcement. To eliminate the risk of corrosion, a practical solution is being sought to protect the inside of the already installed hat beams, especially at the welds.

The challenge here is that with a traditional coating solution, all beams must be opened to their full length to allow blasting and coating/painting. In order to reach the beams properly, parts of the concrete structure must also be removed. A very time-consuming and expensive operation.

nC Group adopted the application of nC Corrosion Passivator – Fluid as they have been treating the ballast water tanks of ocean-going vessels for many years and was commissioned to apply this process to the Top Hat Q beams.

The requirements from the construction company:

  • Durable solution with warranty
  • No movement or opening of the structure
  • No dangerous work
  • Rapid application to avoid as much garage closing time as possible
  • Possibility of periodic checks on the inside of the beam

First, one hole is drilled at the top of the hat beam (highest side) and then a hole is drilled in the same hat beam at the bottom (lowest side). This gap is now being stopped. nC Nano Corrosion Passivator Fluid floats on water. In a ratio of 2 liters of passivator to 1 m³ of volume, the nC Nano Corrosion Passivator Fluid is poured into the hat girder. Then the girder is filled with water. As a result, the passivator is “lifted” by the rising water level and settles on the metal inside of the THQ beam. After complete filling, the stopper is then removed from the bottom of the top hat beam. This causes the water to run off again and the passivator to be distributed over the metal surface once more. The corrosion passivating particles contained in the passivator fluid form a bond with the surface (electron pairs) and in this way prevent new rust formation and stop any corrosion process already present.

Benefits passivation of hat beams with nC Corrosion Passivator – Fluid for Dekamarkt:

  • Long-term protection against new and existing corrosion.
  • No time wasted opening up the THQ beams.
  • No huge cost and risk of deformation due to opening of THQ beams.
  • No need for blasting or corrosion removal in existing beams.
  • Corrosion passivation at rust prone areas prevents recurring corrosion.
  • Very cost-effective solution compared to traditional approach, saves factor 20, where traditional solution of opening and coating is actually not feasible.

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