Cryogenic sandblasting:
technological stripping !

Discover in this article the process and the advantages of cryogenic sandblasting, a process derived from cryogenic stripping.

What is cryogenic sandblasting?…
What does this technique consist of?

For the vast majority of people, the term Cryogenic sandblasting is the expression
which refers to the technique of stripping surfaces by blasting dry ice or
Dry ice®.

This term can be replaced by “dry ice cleaning”, “cryogenic stripping” or “cryogenic cleaning”, insofar as only dry ice is sprayed.
In the case where the use of an abrasive supplement is used, for a thorough stripping effect , it is then called “cryogenic scrubbing” (cryogenic cleaner + abrasive kit or scrubbing kit): this process involves more thorough protection by tarpaulin.

In this article we will only focus on the process involving only the projection dry ice. For the technique using a “cryogenic scrubbing” abrasive supplement, see below: “For more information”.

Cryogenic sandblasting: how does it work?

As mentioned above: the cryogenic sandblasting technique uses dry ice as a stripping or cleaning agent. Dry ice in contact with pollution peels off, leaving the treated surface clean and dry. The process is extremely effective.

One of the many differences with sandblasting stripping is also that the cryogenic process does not cause abrasion on the treated substrate, because the hardness of dry ice is close to that of chalk.

Another difference with abrasive sandblasting is that the dry ice disappears, leaving only the pollution on the ground.

Illustration :

The cryogenic sandblasting process in detail…

Dry ice or dry ice (solid CO2) is projected onto the surfaces to be decontaminated using compressed air.
The supersonic speed of the ice projection on the pollutant takes off the latter without damaging the support.

3 instant actions take place:

1- The kinetic energy transferred to the dry ice (speed of the compressed air), is transformed into energy by the impact of the ice on the pollutant: creation of “micro-cracks” on the dirt.

Please note: The hardness of dry ice is only 2 mohs (hardness of chalk), so it does not create abrasion on the support. Cryogenic sandblasting does not remove deep rust: only the rust flower.

2- The temperature of dry ice at -80°C causes a temperature difference between the pollution and the support: the pollution shrinks under the action of cold, this phenomenon is called “thermal shock”.

Note: the sweeping or firing during the cryogenic sandblasting operation lowers the surface temperature

of the support by 8°C on average, compared to the ambient temperature.

3- Dry ice, on impact, passes from the solid state to the gas state in a ratio of 1 to 400: sublimation.

The dirt is then blown away.

Note:


on the ground no water, no abrasive… just the pollutant removed.

Discover the explanations of the process in pictures

Implementation of the cryogenic blasting process

To perform a cryogenic sandblasting operation, you must have:

1- Dry ice blasting machine, dry ice, compressed air (dry and clean), gun and nozzle(s)

2- The first step is to connect your blaster (as well as the 220 V power supply, if electro-pneumatic) to a compressed air source.
3- Then, connect the firing hose, as well as the gun and nozzle adapted to the job.
Fill the hopper with dry ice, and start the system.

The blasting of dry ice is carried out from top to bottom: the speed of the work depends on the speed with which it is done. from which the pollution is detached. The choice of nozzle, dry ice consumption and pressure and air volume affect the performance of the process.

The advantages of cryogenic blasting or dry ice blasting

As mentioned above, the process is not abrasive because the hardness of dry ice is close to that of chalk: however, in order to ensure the feasibility of a dry ice blasting project you must carry out a preliminary test.

As the medium used is solid CO2, the latter sublimates (goes from a solid state to a gas), leaving only the detached pollution on the ground: no reprocessing of secondary waste.
This process is ideal in industries, where no source of external pollution must interfere with internal production.

Dry ice is also called “dry ice” because it does not go through a liquid phase when it is sublimated. She is also non-conductive (up to a certain voltage), allowing firing on uncovered under-tensioned surfaces: caution use
the appropriate equipment and follow the “certifying” training for this type of work.

Cryogenic blasting is also 2 to 8 times faster than traditional methods.

Example: cleaning conveyor chains in the food industry 2X 750 linear meters

• Traditional method (high-pressure cleaning):
  2 operators carrying out 7 days of work including 2 days of dismantling, 3 days of cleaning and re-lubrication, 2 days of reassembly
  Production shutdown (24 hours): 7 days

• Cryogenic sandblasting method:
  3 operators working 2 1/2 days: including 2 1/2 days of cleaning. No disassembly, no reassembly
  Production shutdown (24 hours a day): 2 1/2 days