Patent ID: 8733446

Claim:
A riser installation using a flexible pipe of the unbonded type, wherein the pipe comprises, from inside outwards, at least one internal sealing sheath and two layers of tensile armor wires wound with a long pitch; the installation further comprises: a head mechanical connection toward the sea surface, a submerged buoy at the head mechanical connection, a foot mechanical connection with the seabed, the pipe being arranged vertically between the head and the foot mechanical connections; the head mechanical connection includes a connecting upper end fitting, the buoy has a central bore for passage of the pipe and a first diameter of the bore being greater than a second diameter of the connecting upper end fitting of the pipe; fluidic connections at the head and at the foot mechanical connections to connect the riser respectively with surface equipment and with seabed equipment; and wherein the foot of the riser experiences a calculatable maximum reverse end-cap effect, at a depth of at least 1000 m and the buoy is configured to apply to the foot of the riser a reaction tension greater than at least 50% of the calculatable maximum reverse end-cap effect developed at the foot of the riser.