| 摘要 |
A rigid pipe-in-pipe structure for subsea transportation of fluids comprises inner 30 and outer 22 pipes defining a thermally-isolating annulus between them. Thermal insulation material 20 is disposed in the annulus. The outer pipe 30 is made of metal, preferably carbon steel. The inner pipe is a polymeric composite structure of bonded layers comprising a first, radially outer tubular polymeric electrically insulating layer 32, which may be of pure polymer, surrounding a second, composite layer 18 comprising reinforcement fibres, preferably continuous carbon fibres, embedded in a polymer matrix. Conveniently the second layer is a heating layer in which the carbon fibres conduct electricity to heat the inner pipe 30. The inner pipe 30 may also comprise a radially inner tubular polymer layer 34 within the second composite layer. The inner pipe 30 can comprise a series of longitudinally spaced formations 38 protruding radially outward from the outer layer 32 of the inner pipe 30. These formations 38 can be formed integrally with, or bonded onto, the outer layer 32. |
