Hull integrity is a critical part of being able to stay on station for extended periods.
Good hull integrity requires meaningful and accurate data on hull condition and this comes from high quality inspection. Regulators require operators to assure hull integrity and this requires inspection of the hull internal structure as well as isolation valves, elements of marine piping, external appendages and mooring systems.
Current methods for external inspection of floating assets on-station use divers or ROVs but these methods incur high safety, POB and cost penalties. The data produced by current methods is restricted by marine growth and limited access to isolation valves.
The HITS (Hull Inspection Techniques and Strategy) JIP called for new methods to be developed that minimise or eliminate diving. This has now been achieved by carrying out many of the inspections from inside the hull and using advanced methods to inspect critical isolation valves and marine piping and inspection of the hull appendages by mini-ROV fly-past.
Avoiding additional tank entries for the inspections from within the hull is achieved by agreeing continuous survey ‘Long Term Inspection Plans’ that align the ‘underwater’ scope with tank entry for Continuous Hull Survey Programmes and spread the inspections over a 5 year cycle which is updated and repeated for the required life cycle of the asset.
Benefits of this alternative method include over 20% cost reductions and 70% reductions in POB (Persons On Board) coupled with minimal weather / sea state downtime and much improved inspection data.
Further advances in hull inspection are currently being developed to eliminate man-entry of confined spaces, such as tanks, and the inspection of cargo tanks with minimal cleaning effort.
This paper describes how these rapid advances have been made on inspection challenges identified by the HITS JIP and close cooperation between Operators (SBM), Classification Societies (ABS) and Service Providers (EM&I).