Patent ID: 8387703

Claim:
A buoyancy can system for tensioning a plurality of top tension risers, the buoyancy can system comprising: a plurality of tubular cans coupled together and configured to move collectively as a single unit; wherein the plurality of tubular cans are coupled to the plurality of top tension risers and are configured to apply a tension load to each of the plurality of top tension risers; wherein each tubular can comprises: an upper end enclosed by a lid having an opening therein; a closure device coupled to the lid and configured to close the opening and then open the opening to increase the level of seawater in the tubular can and decrease the tension load applied to the plurality of top tension risers; an open lower end configured to allow seawater to flow freely into and out of the tubular can; and an inner surface extending between the upper end and the lower end, the inner surface devoid of structural obstructions which substantially inhibit the free flow of seawater through the lower end; and a pressurized gas system configured to selectably inject pressurized gas into one or more of the tubular cans; wherein, when the opening is open, the tubular can is ballasted by seawater; and wherein, when the opening is closed and pressurized gas is injected into the tubular can, the tubular can is de-ballasted of seawater.