Ice Pigging™
& Cooling Networks
When commissioning district heating or cooling networks, all newly laid pipes have to be cleared of sediment and particulate contaminants before the system can be made operational. Cleaning these out with conventional methods such as water flushing can take several weeks and require significant amounts of power and chemicals.
Ice Pigging™ produces equivalent results to solid pigging, without any of the associated challenges; the ice can navigate complex pipework including diameter restrictions, bends, valve systems and other obstructions with no risk of becoming stuck. It can also be inserted and removed from the network using existing fill and drain vents.
Ice Pigging™ can be used as part of the commissioning process on new networks, or as a maintenance technique on existing pipework.
Ice Pigging™ is generally applied on larger bore pipes (between 40 and 500mm); therefore it is most commonly used on below ground pipework running between the energy centre and plant rooms.
The process
An ice delivery unit will pump ice slurry into the pipe through a suitable fitting at one end of the pipe.
Once the ice has been inserted, the in-situ pumps can be used to push the Ice Pig™ through the full length of the pipe. Alternatively, an external pump and water supply can be used.
At the outlet, the clean water within the pipe is discharged to ground and the dirty ice is collected in a waste tanker.
After a short flush to remove the ice residues, the cleaning is complete.
Time: Each pipe is cleaned in a single pass and most networks can be cleaned in a single day
Cost: Highly cost effective with zero chemical and pumping costs for the full process
Ease: Ice is inserted and ejected using existing vent points, no network modifications required
Low risk: Exceptionally low risk – if ever the ice gets stuck, it will simply melt down
Effectiveness: A physical clean is undertaken rather than just a flush. Produces quantifiable results – proof of quantity of sediment removed
Environmental Benefits: Low energy use with no chemicals to dispose of
Example of Ice Pigging™ in operation
“We have used and specified Ice Pigging™ on all of our larger diameter installations, as the dynamic flushing on these pipes can be incredibly difficult due to the flow rates required. Ice Pigging™ has proved to be a much simpler method for the dynamic flushing element of the works and it has allowed us to reduce the overall timeline of the commissioning process.” Eneteq Services
The Issue: Our client, a district heating specialist, installed 4,000m of heating transmission pipes at the redevelopment of Wembley Park. These pipes transfer heat from the purpose-build Combined Heat & Power plant to each of the residential blocks providing 8,400 new homes at the seven acre park.
Before the transmission pipes can be used, they must be carefully cleaned to remove any particulate matter such as swarf or construction residues which could damage the heat exchangers or shorten the life of the pipework.
The Solution: The mobile Ice Pigging™ team conducted four phases of pipe cleaning work between December 2018 and February 2021, as each phase of installation was completed. The four thousand meters of pipework to be cleaned, with diameters ranging from 25mm to 250mm was broken into several distinct Ice Pigging™ runs, with each taking between 15 and 60 minutes to clean.
The Results:
- Each section cleaned in a single pass in a matter of hours. The process is much faster and more straightforward than dynamic flushing. Cleaning for each phase took less than a day, saving 13 days from the commissioning process
- Each run was refined to ensure smooth integration with the other activities on the building site.
- No specialist pumping equipment required so lower levels of power consumed
- Existing fill and drain vents were used on the network so no excavation required.
- No harmful chemicals used.
- The combined total time for cleaning the entire network was 27 hours.