Ensure ENGIE a continuous service in the extension of a pipework connection in London

In line with the London plan energy strategy, the Energy Statement proposed a residential development program favoring Renewable and Low or Zero Carbon (LZC) technologies in construction projects to offset a proportion of the developments carbon emissions.

ENGIE has been involved in the Angel Lane District Stratford project consisting of the extension of the existing Heating and Cooling pipework connection as part of the construction 33 storey tower block with 181 apartments. In total, 1560 meters of 300 mm diameter pipe had been installed.
The District Cooling pipework needed to undergo a pre-commissioning clean to remove swarf and construction debris from the pipework before it could be put into service. A conventional flush of the network would have taken approximately 1 week and required high flows and pumping costs.  

When operational, the District Cooling network will cycle chilled liquid from the Stratford Energy Centre around several hotels and apartment buildings, to be utilized for air conditioning and refrigeration systems. This centralized approach can be up to 40% more energy efficient than each building having an individual cooling plant

SUEZ has previously carried out several other pre-commissioning Ice Pigging® operations on ENGIE networks, so it was the obvious choice for this project.

The ice slurry was pumped into the pipework to form a long ice pig, this was then driven through the pipework by pushing water in behind the ice.

As the pig traveled through the network it has collected any swarf, welding debris and accumulated sediment which is then discharged from the network suspended in the ice. The operation also collected a large piece of insulation which had been left in the pipework during construction. Any objects like this can cause serious blockages if not removed before the network goes live.

Water in front of the pig is discharged normally while the sediment laden ice had been collected separately in a tanker for safe disposal. All of this took place without exceeding the normal operating pressure of the pipework or causing damage to the pipe wall.

SUEZ was able to utilize existing fittings for all pipe connections and therefore no enabling works were required for the operation.

All pipe was cleaned with Ice Pigging® in one day which related to big time saving at the end of a civils project with a tight schedule. The District Cooling networks in-situ pumps were not used at all during the process which represents a significant energy saving when compared with closed loop flushing, which requires high velocity pumping for several days. 
Ice Pigging produces superior results compared to flushing as it involves a physical cleaning action, rather than just a high velocity flush.

It also poses significantly lower risk than using foam pigs which can become stuck requiring excavation to remove. Ice Pigs can deform around obstructions in the pipe and if one ever were to get stuck, it would simply melt.  
Approximately 25 tons of ice were used for this operation which was manufactured in Bristol and transported to site, however we also have mobile ice manufacturing equipment for operations further away.