Dry Ice Blasting in a confined space of a casting vacuum unit
More new and exciting projects recently completed by the Optimum team included a dry ice clean down of a casting vacuum unit.
Whilst the blast itself was rather straight forward, the dust control was anything but! If anyone reading this works with a Consarc 350 casting unit, or has blasted one, then you will know exactly what I’m talking about.
The internal machine surface becomes covered in a carbon deposit that has to be removed as it effects product quality after a period of time. The removal process sends the carbon airborne and, as we are working in a confined space, reduces visibility to virtually zero. We use powerful vents to push air in at one end, and filtration/dust control to extract (as much as we can) at the other end.
The problem when working inside a tank is that the nature of our blast guns means the air vortexes around, and with it the dust. To create a safe working environment for the teams these were the processes put in place:
- ATEX rated spot lights – this enabled the crews to, not only see what needed to be removed, but also to make sure that we weren’t damaging any vital components and that we had safe entry and exit movement.
- Positive Air flow/extraction systems
- 2 man crew inside the tank (one blasting, one observing and swapping roles every 15 minutes) 2 man crew outside the tank (swapping roles with the internal crew every hour)
- obligatory confined space PPE – air fed helmets
- obligatory confined space PPE – harnesses and ‘man down’ extraction winch systems
- obligatory confined space PPE – explosion control and monitoring
- obligatory confined space PPE – CO2 gas monitoring
The process was safe and controlled and the customer was very pleased with the quality of the clean and also the time taken to complete.
- The blast time was 6 hours and 100% of the contaminant removed from the surface.
- The traditional method of cleaning involves 5 operatives using scotch bright pads. This can take up to 4 days and 100% removal isn’t guaranteed.
- The machine downtime costs are estimated at losses of between £8K and £12K per day.
- The saving to the company is estimated at around £40k per machine (5 machines in total)
We have now been asked to quote for the remaining 4 machines at the site and have been included on a monthly cleaning schedule.
All in all a very successful blast and I’d like to thank the crews involved for their professionalism, input and hard work.
By Ian Reynolds