iNPIPE PRODUCTS™

Large Diameter Trunk Main Swabbing & Flushing

Large-diameter foam swabbing pig being deployed during trunk main cleaning and flushing operations.

iNPIPE PRODUCTS™ was engaged by Farrans, working on behalf of Northumbrian Water, to deliver pigging operations on a newly constructed large diameter trunk main forming part of a strategic water infrastructure scheme in the North East of England. The pipeline was designed to convey treated drinking water to service reservoirs and to support future network expansion.

Client Requirement

Farrans required specialist pigging support to undertake swabbing and flushing of newly installed DN900 and DN800 steel trunk mains prior to commissioning.

The works were required to achieve a suitable standard of cleanliness to enable subsequent disinfection and water quality sampling, ensuring the pipeline could be safely brought into potable water supply.

The project involved a complex pipeline arrangement incorporating large diameters, multiple sections and both single and twin main configurations, requiring careful planning and phased execution.

Pipeline Scope

The scope of works covered over 33 km of newly installed steel potable water trunk mains. The pipeline comprised large diameter sections of 900 mm and 800 mm, configured as a combination of single and twin mains along the route. The system also incorporated a route split with provision for a future connection, allowing for network expansion at a later stage.

Pigging Operations

To ensure effective cleaning and controlled execution, the pipeline was divided into multiple discrete sections.A combination of water-driven and air-driven pigging techniques was selected to suit pipeline geometry, elevation changes and site constraints.

The availability of sufficient water volumes along sections of the pipeline route was a key operational consideration. As the project progressed, the pigging methodology was adapted in response to site conditions. While water-driven swabbing formed the basis of the cleaning strategy, air-assisted pigging was selectively adopted in sections where water availability influenced operational planning.

Specialist foam swabbing pigs were designed, manufactured and deployed, including bare foam pigs and criss-cross coated foam pigs, selected to provide effective sealing and debris removal in large diameter pipelines and to support potable water commissioning requirements. All pigs were fitted with tracking transmitters to enable real-time monitoring and positional verification throughout each pigging run.

Site setup activities included the installation of temporary launchers and receivers, associated pipework, pumping and compressor equipment, and access scaffolding at each work location.

Project Outcome

The project was completed safely, on programme and in compliance with environmental and commissioning requirements. The successful execution of the swabbing and flushing operations enabled the pipeline to be prepared for potable water commissioning, supporting timely introduction into service and ensuring readiness for future network expansion.

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