INNOVATION EDGE™: ROLLDOWN PROCESS
The Rolldown process, used by Land & Marine Engineering Ltd, is a pipe insertion technique that maximises the diameter of the inserted pipe, while reducing carbon emissions and local environmental impact associated with traditional techniques.
Description
Rolldown is a site process that allows the installation of close-fit polyethylene (PE) liners into existing pressure pipelines. The intellectual property of the Rolldown is owned by Land & Marine, a wholly owned subsidiary of Murphy.
The machinery used in the process is provided by Subterra (Radius Systems).
The on-site process involves reducing the diameter of the PE pipes, inserting them into the existing pipelines, and reversing them to their original size. The dimensions of the PE pipes are specified so that their maximum external diameter is equal to the internal diameter of the existing pipeline.
The PE pipes can be welded together prior to processing. The pipe string is fed through a series of rollers, reducing the diameter of the pipe by around 10%. The reduction of the PE pipes is done at temperatures above 0°C. Approximately 1m of pipe can be reduced per minute.
The reduced diameter PE pipes are fed through the existing pipework using slipline insertion. The distance between the pipeline access points are dependent on the slipline machinery used, however insertions of typically 750m can be achieved. Once inserted, the ends of the pipe are sealed and water is introduced to the system. Water pressure within the pipe is slowly increased, causing the pipe to revert to its original diameter.
Benefits
- The Rolldown technique maximises the diameter of the inserted pipe, using as much of the original pipe possible.
- Unlike traditional open cut techniques, the Rolldown method does not require lengthy excavations. This leads to a number of significant benefits, including:
- Avoiding disruption of local ecology, structures, roads and areas of historical interest.
- Reducing excavation and its disposal to landfill, as well as purchase and delivery of infill materials.
- It minimising the time spent on excavation and backfilling activities.
- Reducing impact on businesses and stakeholders, including requirement for traffic control.
- Decreasing hazards associated with trench digging (such as landslides and striking buried services).
- The North American Society for Trenchless Technology (NASTT) suggests that in comparison to open trench method, the Rolldown process technique can achieve carbon emission savings of up to 95%. In addition, the PE pipes can be specified to either have full structural capability or rely on the structure of the original pipe.
