Why is a dehumidifier system important for anti-corrosion paint application

In the marine industry or in other industrial sectors where bare metal parts are exposed to the weather, different layers of paint must be applied to exterior steel to protect it from corrosion. Prior to the application of paint, however, the sand blasting process must be performed.

Sand blasting is a dry process of cleaning and surface preparation of metal products. It consists of projecting a high energy jet of sand onto a metal element to remove from its surface any metal oxides, traces of sand in the castings, paints, grease, and other unwanted components. Generally, this process is intended to obtain a clean and rough surface on which to subsequently perform other treatments for its protection.

High humidity is not suitable if you want to avoid corrosion of the substrate surface during and immediately after this abrasive cleaning. The white steel resulting from the abrasion process is highly susceptible to oxidization and requires a relative humidity of less than 40% to ensure that the steel remains corrosion free.

One method sometimes used to reduce relative humidity while performing abrasive cleaning is to heat the surrounding air. While this reduces relative humidity (%RH), it doesn’t actually remove water or reduce the water content of the air. In fact, heating the air will allow you to retain more water before saturation. Dehumidification, on the other hand, effectively reduces the moisture content of the air, providing a better solution.

Using a desiccant dehumidifier to introduce dehumidified air into your sandblasting enclosure will significantly reduce RH, which in turn will decrease the risk of oxidation. Reducing moisture to less than 50% relative humidity will allow you to keep the blasted areas of steel uncoated for days, reducing the need to clean and paint immediately after each blasting, meaning you can keep cleaning longer and meet production goals more quickly.

Among the many air-drying processes, desiccant rotor technology has been shown to best combine the highest application range with the lowest installation and operating costs.

Steel corrosion curve

FISAIR has developed desiccant rotor dehumidifiers specifically for these processes – the DFRC series – and has been supplying them to reputable customers and applicators of renowned prestige in the industry for more than twenty years.

The DFRC range is supplied as standard with a lifting frame and roof for temporary or mobile applications

This allows the units to be easily transported and is designed to withstand the aggressive environments in which they are required to function. In addition, they have a simple comprehensive control for the safe and efficient operation of the drying process.

DFRC | Air dehumidifiers for outdoor environments | Fisair

As an example of application, FISAIR supplied 12 DFRC 2100-E and 4 DFRC-1300-E modules to NAVALIA shipyards for moisture control within the tanks of meth vessels, during the internal coating phase of LNG liquefied natural gas tanks.

Application References

Some outstanding references:

    • Dragados Off-Shore 
    • Navantia 
    • DCNS 
    • Astilleros de Pasajes 

    • CNN 
    • Ulstein verft as 
    • Kleven verft as 
    • Havyard Group 

    • Simek A/S 
    • Bergen Group asa 
    • Fiskerstrand verft as 
    • Sharvik as 

    • Vaagland Batbygeri as 
    • Fitjar mekaniske verksted as
    • Truku meyer 

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