Numéro : 2456 - Year : 2005
New rules for the FPSO units classification
Etienne ARSELIN, Bureau Veritas - Division Marine – Paris (France)
Ulrick FRORUP, Bureau Veritas - Division Marine – Paris (France)
Phillipe CAMBOS, Bureau Veritas - Division Marine – Paris (France)
Michel HUTHER, Bureau Veritas - Division Marine – Paris (France)
Bureau Veritas is preparing a full set of classification rules covering the different systems of an FPSO. The present document deals with the structural assessment of the hull.
Based on the recent return of experience, Bureau Veritas has developed new rules for ship-shaped (or box-shaped) FPSOs, based on the ship classification rules, taking into account the specificities of the FPSOs: units fixed on a specific site, units permanently moored (no dry dock scheduled for inspections and maintenance), units continuously loading and unloading on site (constant variation of draught).
The rules so consider a direct hydrodynamic analysis, taking into account the metocean data of the site and the mooring conditions, with the purpose to define the sea loads on the structure. The required structural assessment is carried out taking into account the results of the hydrodynamic analysis, and includes the following steps: global strength assessment (yielding and ultimate), local structural assessment, based on a 100 year return period, impacts (bow impact, flat bottom reinforcements, sloshing), spectral and deterministic fatigue assessment and collisions, explosions, dropped objects.
The contents of those various items are presented and discussed.