Unbonded flexible pipe

Abstract

The invention relates to an unbonded flexible pipe for sub sea transportation of fluids. The pipe has a length and comprises a tubular inner sealing sheath defining a bore and an axis of the pipe. In a pipe length section it comprises a second sealing sheath surrounding the inner sealing sheath and forming an annulus between the inner sealing sheath and the second sealing sheath. The annulus provides a primary maintaining passage along the length of the pipe length section with a first and a second end. The pipe comprises at least one secondary maintaining passage along the length of the pipe with a first and a second end. The secondary maintaining passage is arranged with an axial distance which is larger than the axial distance of the inner sealing sheath. The first end of one of the primary and the secondary maintaining passages is arranged as an input end for a maintaining fluid and the first end of the other of the primary and the secondary maintaining passages is arranged as an outflow end for the maintaining fluid, and the primary and the secondary maintaining passages are in fluidic connection with each other at their second ends to provide a pathway for the maintaining fluid. The pathway for a maintaining fluid makes it possible in a simple and effective manner to keep the corrosion of elements—such as armouring elements in the annulus—relatively low, and accordingly the duration of the unbonded flexible pipe can thereby be increased.

Dependencies are inferred from the claim text.