Competence in surface protection
and coating

Manhole refurbishment

For the refurbishment of manhole covers we recommend a surface preparation with dry ice blasting and two-component coating substances with brief overcoating times. This way your benefit is twofold: an increased protection from corrosion and a less time-consuming and therefore cheaper application.

We carry out the blasting work with a dry ice blasting machine specially designed for this purpose. In order to be able to operate the system, a high-performance compressor is connected with special separators that have to transport absolutely dry air. The air flow rate must be at least 10 m3/h. An operating pressure of 12 bar is required.

For the coating of the frame and bottom surface of the manhole cover we use two-component coating substances. For the base coat we use a two-component epoxy priming with excellent adhesion characteristics on various surfaces and extraordinary chemical durability. Depending on temperature, the primer can be overcoated after as little as one hour. For the subsequent cover coating we use a two-component top coat with high resistance to weather and chemicals. The coating substances are applied manually with brush or roll.

Dry ice is solid carbon dioxide (CO2), which, unlike other abrasives at normal pressure without liquefaction, passes directly from the solid to the gaseous state (sublimation). Other features: Dry ice is non-toxic, electrically non-conductive and non-combustible.

The dry ice pellets used for cleaning are accelerated with compressed air and hit the surface to be cleaned at high speed. The layers to be removed are locally undercooled and brittle. Subsequent dry ice particles penetrate into these brittle cracks and sublimate abruptly when they hit. The carbon dioxide becomes gaseous and increases its volume by a factor of 700 to 1,000. Impurities and corrosion products are blown off the surface.

Advantages of dry ice blasting technology
  • Minor damage to the material to be cleaned.
  • After processing, no abrasive to be disposed of remains, as the CO2 evaporates gaseously into the ambient air.
  • Thanks to the soft abrasive dry ice (hardness according to Mohs: 2 – 3), this process can also be used to clean extremely sensitive electrical components with cable connections.
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