Hull scanning of ageing tankers provides owners and managers an effective tool to optimise the requirements for steel renewal. The hull scanning system is based on a remotely operated vehicle (ROV) continuously recording the shell plate thickness giving a detailed picture of steel condition.
Single hull tankers passing 3rd periodic class renewal, e.g. 15 year and older have experienced significant internal corrosion in the bottom plating. Extensive corrosion may result in high cost related to steel renewal in drydock as well as it will reduce the possibility obtaining a first class CAP rating for the vessel.
By scanning the vessel prior to drydocking, giving a detailed picture of the steel condition, the owner and manager are enabled to optimise the requirement for steel renewal. Further, the results can be applied for optimisation in relation to the condition assessment program (CAP).
DNV and the Fred. Olsen related companies Ganger Rolf and Bonheur have entered into a joint project based on patented technology. Red Band is appointed project manager offering Hull Scanning services to the market.
Detailed picture of steel condition
The Hull Scanning system is based on a remotely operated vehicle (ROV) continuously recording the shell plate thickness giving a detailed picture of steel condition. The operation can be performed in ballast or loaded condition while the ship is at anchor - no tank cleaning or gas freeing required. Typically, an operation for a Suexmax tanker takes 24 hrs, a VLCC 48 hrs and ULCC 60 hrs.
Results from the Hull Scanning shows a clear picture of the tanks, original plate thickness and corrosion patterns. Further, the results are processed in relation to class or CAP criterias in order to highlight areas requiring attention.
For vessels having limited margins in relation to the requirements, great success have been obtained by utilizing the results in an optimisation process based on calculation of strength.
Date: 2003-05-15