Pure foam systems
Pure foams offer many advantages over macrosphere composite foam systems including robustness, ease of repair and modification in the event of damage or design changes, and extremely low water ingress rates. It should be noted, however, that these are ‘premium products’ and are therefore typically selected for more demanding service conditions such as extreme operating depths and/or service criticality such as manned service.
Two ranges of pure syntactic foam are available, differing primarily in core density. Both the “Standard Range” and the “Ultra-Low Density Range” are normally produced in pre-cast blocks. These blocks may be supplied for client assembly or can be factory assembled into finished buoyancy modules.
The buoyancy performance of the ultra-low density material is understood to be unique amongst ROV buoyancy foams in that the buoyancy does not progressively reduce due to hydrostatic compression as the ROV flies into deeper water. This is because the bulk modulus - ie, the compressibility under hydrostatic pressure - of the foams is marginally less than sea water.
ROV/AUV external finishing
The selection of a barrier coating on buoyancy modules of any type is a critical issue. These coatings provide impact and abrasion resistance while offering high visibility smooth gloss finishes.
The most frequently supplied ROV/AUV coating is a 3-5mm spray applied elastomer. This is applied to all upper and external surfaces to give a very effective coating for work class ROVs.
Standard finishes are provided in smooth high gloss yellow, orange, red or white. Other colours are available to suit project parameters.
Where a quantity of modules of the same generic shape is required, in applications such as skid module blocks or trim modules for example, Balmoral provides an alternative to PU or GRP skins by utilising rotationally moulded polyethylene shells.
Polyethylene is a material used extensively in the offshore industry and these shells can be manufactured for heavy duty applications with thicknesses ranging from 6-14mm.
Provision should be made within the design to accommodate the tolerances applicable to rotationally moulded products.
