In order to meet the requirements for lower boil-off, as a first step, the perlite in the boxes has been replaced by glass-wool: NO96 GW. It has to be noted that this evolution is not a structural change. The bearing plywood structure is kept identical to NO96 system. The guaranteed boil-off rate with NO96 GW system is between 0,125% and 0,13% V/day.
For an ever better thermal efficiency, NO96-L03 is proposed: within the usual NO96 thickness, three layers of boxes are assembled. The primary boxes are totally identical to NO96 system. The NO96 secondary boxes are replaced by intermediate plywood boxes assembled with a third layer of insulation made from R-PUF (foam panel). In the N096-L03 configuration, only standard rectangular boxes are replaced with the foam panel design (except highly reinforced areas at the top of the tank). As a consequence, 66% of total surface of the tank is covered by NO96-L03 design. The plywood boxes are filled with glass-wool. The guaranteed boil-off rate with NO96-L03 system is 0,105% V/day
These evolutions have been approved by classification societies based on a complete justification dossier (calculations, tests, cryogenic scale 1 mock-up).
In order to meet requirements for systems sustaining higher sloshing loads, a set of different boxes corresponding to different levels of reinforcements are proposed. For classical LNGC applications, the standard, standard-reinforced and ultra-reinforced boxes are sufficient.
Depending of the specification of the project, higher levels of reinforcement can be needed. This is the basis of the development of the Mega-Reinforced design. The plywood structure is reinforced by increasing the thickness of primary box double cover and secondary box internal bulkhead.
Boil-off and reinforcements can be optimized according to ship-owner specifications.
NO96 Mega-reinforced design