FEATURE SPONSOR
ROVS CASE STUDY TOOLKIT
The culmination of this ongoing development that has spanned 15 years is UTROV`s Generation 4 System. This tool kit includes a MFE, clamshell bucket, tined grab, shear grab, timber grab, sampling grab and mattress laying frame; all of which can be changed out on deck quickly to ensure the UTROV can handle a range of tasks.
The UTROV provides a subsea platform and means to operate and control hydraulic systems, existing tooling from the construction industry can be easily adapted to work subsea or new tooling can be developed to carry out specific tasks.
Late in 2014 UTROV were employed by Briggs Marine to provide subsea support for the recovery of a 29t tool that was partially buried in 105 metres of water. Approximately 110 meters of tow wire and umbilical were still attached to the tool potentially hindering ROV operations.
The remit was to dredge around the tool, lift it clear of the sea bed and move it to a site approximately 3 miles away with a water depth of 20 metres. Here it would be positioned on the sea bed for Briggs divers to replace the lifting harness prior to recovery.
THE KEY OPERATIONAL STAGES WERE IDENTIFIED AS… • Survey • Possible removal of tow wire & umbilical obstructing access
• Excavation around the tool • Attaching a hoist wire • Lift the tool clear of sea bed • Move the tool to a pre-identified site • Lower and uncouple the tool
THE CONVENTIONAL APPROACH Use a combination of an ROV and a MFE to carry out the operation. The vessel used would have needed sufficient deck space for the 2 systems, berths for the operators and a winch or crane to support the operation.
THE UTROV APPROACH The adaptability of the UTROV made it possible to quickly engineer solutions for the various problems associated with the project…
1 A timber grab was purchased and modified to interface with the UTROV. This was fitted whilst carrying out the survey of the tool to allow the immediate removal of the tow wire and umbilical
2 On completion of the survey the MFE was attached and deployed. Two acoustic cameras were fitted onto the UTROV allowing the operator to closely monitor the excavation site at all times
3 A two wire grab was designed for latching onto the stranded tool and lifting it without damaging it. This was designed, manufactured, tested and delivered in 10 days. Key factors in the design of the two wire grab were that it would grip hold of the tool without causing damage and that it would be able to release the grab from the tool should the need arise due to deteriorating weather
4 The two wire grab (weighing 2.5t) was suspended in the open position from the UTROV using the timber grab to hold a buoyant spreader bar (See inset picture). Once in position the timber grab was released transferring the load onto the main winch wire of the vessel. An additional buoy provided a constant tension on the winch wire preventing the grab from being unintentionally released with the vessel movement in the swell
5 The UTROV was recovered to the surface and the tool was successfully lifted and repositioned using the vessels main winch. The UTROV was deployed again to grip the spreader bar releasing it from the tool
A SUCCESSFUL AND COST EFFECTIVE SOLUTION
This was a successful operation all carried out from Briggs Marine’s capable 61.2m x 13.5m vessel with a crew of 11 and a 4 man UTROV team providing a cost effective solution to the client.
Utility ROV Services Click to view more info
www.windenergynetwork.co.uk
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