World's most powerful trenching machine from SMD HydrovisionVessel & ROV News // November 7, 2006
SMD Hydrovision in the UK says it has recently completed successful testing of what it claims to be the world’s most powerful subsea trenching machine.
The 2MW pipeline trencher was designed and built for the Sea Trucks Group, based in Nigeria.
The system was tested in the River Tyne immediately adjacent to where it was manufactured at SMDH’s Turbinia Works.
"The machine created quite a splash when it was tested at full power," said the company, "sending plumes of water 50m from its powerful dredge pumps. The system is now on its way to Nigeria where it will be used next year."
The contract to build the machine was the result of two year discussions between SMDH, Sea Trucks and their clients (Shell Petroleum Development Company Nigeria and Hyundai Heavy Industries) to find a solution to protect two new pipelines they will install for the Bonny Island Terminal Project.
The 36in and 48in lines will be installed and buried between two existing live lines from the beach to offshore. Conventionally, the lines could have been pre-trenched using a cutter suction dredger.
However, since the existing lines lie close together, conventional dredging would present a serious risk to these lines, as offshore class dredgers can only prepare large access channels.
The solution developed by SMDH is a powerful self contained jetting and dredging machine, which runs on rollers on top of pipeline.
The machine fluidises the soil around and under the pipe and removes it using strong dredge pumps. Hence, only a narrow trench is formed under the pipeline, with the resulting limited impact on the environment.
The machine is supported by the pipe and large buoyancy tanks. These can also be lowered by remote control to act as skids in the surf zone. The machine is bi-directional enabling it to make multiple passes between the beach and the support barge without being turned around. The 750m long power umbilical allows it to work at quite a distance from the barge.
The machine will use SMDH’s Distributed VEhicle Control System (DVECS) to precisely monitor and control the trenching process. Power and telemetry will be transmitted via a single armoured umbilical to containerised control and power vans located on the support barge. The umbilical winch is also designed and built by SMD Hydrovision.