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Advanced pipe cleaning cuts costs for utilities

Jun 28, 2016
  • Forced vortex technology uses aggregate to restore heavily corroded pipelines
  • Utility trial demonstrates minimal disruption to customers
  • Multiple benefits deliver whole-life cost savings over traditional techniques

A pipe cleaning system which uses granite aggregate to blast away corrosion could save millions for utilities in the UK. The Whirlwind system developed by HTC, which is part of Manchester-based Aquam, can restore pipes at lower cost than existing systems and with less disruption to customers. 

Case study: Severn Trent Trial

A village in Shropshire where discoloured water was a persistent issue has become one of the first in the UK to benefit from this innovative pipe cleaning technology.

Utility Severn Trent Water worked with Aquam to trial its technology by clearing and chlorinating sections of 30-year-old unlined cast iron pipe in Church Preen.

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The trial was carried out using its HTC Whirlwind system, which blasts a fine granite dust to remove corrosion and restore the pipe to its original diameter, together with the Leanclean system, which flushes and chlorinates the pipe.

Ian Tindell, Business Development Manager, Aquam UK said:

“Church Preen is a rural location served by narrow country lanes, which are used by cows and horses as well as motorists. The 3-inch mains pipe ran under a road with heavy rock ground make up. 

“The advantage of using the Whirlwind and Leanclean system is that it can be used from a single access point, which means there is a minimum amount of digging and disruption.” 

The team from Aquam used Tornado, a vehicle-mounted mobile unit to blast the dried 10mm granite aggregate using the Whirlwind forced vortex. 

The Tornado unit was sited at a central point, in order to blast clean the pipe in both directions.

A spokesman for Severn Trent Water said:

“The work at Church Preen was carried out in just two days, with minimum disruption to customers. A temporary supply was fitted while work was carried out.
“The trial shows the Whirlwind and Leanclean system is a cost effective way to clean pipes, particularly in hard-to-reach locations.”  

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Before and After Cleaning

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Whirlwind can be used in combination with HTC LeanClean, which flushes and chlorinates the restored pipe, leaving it ready for use. The two systems have already been used on 90km of pipeline for one major UK utility while successful trials have been carried out elsewhere. Corroded pipework can lead to issues with water quality and colour, while heavy corrosion can reduce flow and lead to significantly increased pumping costs. In comparison with traditional pipe cleaning systems, Aquam’s HTC Whirlwind and LeanClean are quicker, lower cost, use a minimal amount of chemicals and are less likely to cause accidental damage to the pipework.

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Restoring corroded pipes can be an alternative to pipe replacement, cutting civils costs and disruption to both customer and the public. Access to the main can be through a single point of access, such as a fire hydrant, reducing the need to excavate large sections of the pipe to be treated. 

Pipe sections showing condition before and after HTC Whirlwind cleaning process.

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Beating corrosion

The Whirlwind system targets tubercules, growths caused by corrosion, which can build up on the interior of cast iron pipes, significantly reducing the diameter. In a single operation one kilometre of pipe can be cleared.

Two diesel engines mounted on the rig power blowers use a vortex to create a turbulent airflow. The two blowers can be used together or separately to produce a pressurised airflow in different diameter pipes.

Dry granite aggregate of 10mm diameter is blown along the pipe length, hitting the walls and sweeping away tubercles as it travels - restoring the pipe to its original diameter.

Both Whirlwind and the LeanClean are carried on the same vehicle-mounted rig, with different models and sizes available depending on the nature and scale of the job.
LeanClean is used to flush and chlorinate the pipe after the abrasive treatment process. 

The system uses water droplets carried by an air vortex. It uses a much higher level of chlorine at a much lower volume, with typical contact time of 30 minutes. This reduces the amount of air and water required compared with traditional techniques.
The Leanclean system can also be used to remove soft deposits such as manganese and biofilm from pipes.

Minimal waste

The Whirlwind system has a number of advantages over existing pipe cleaning technology such as the insertion of rotating flails or the use of large quantities of water for flushing.

Rotating flails can often damage existing pipework, meaning additional repairs have to be carried out. Flushing out pipes using large quantities of pressurised water can also cause damage to the existing infrastructure. 

Using water also generates vast quantities of heavily polluted wastewater, which under existing UK legislation has to be transported off site by tanker. By contrast the Whirlwind system generates a small quantity of waste aggregate, which can be used as backfill. 

The Whirlwind system is completely enclosed, with no exposed rotating parts, which minimises health and safety risks on site. The system also operates at relatively low pressures, well below the pressure of the main. 

Relatively large sections of the main can be cleared with only a small number of personnel.  Typically two engineers can clear a section of a main from a single access point within one hour. 

Unlike mechanical systems such as drag scrapers, the Whirlwind system can easily be used for lengths of main with variable diameter or which have ninety-degree bends. The portable equipment can be easily manoeuvred into hard-to-access locations and onto rural sites.