Reinforced submarine pipeline and assembly of two coaxial pipelines comprising same

A reinforced undersea unit pipe element suitable for transporting fluids flowing out in said pipe and suitable for being laid empty and to rest on the seabed at depths in excess of 1000 m, the reinforced undersea unit pipe element comprising:

• a tubular wall comprising:
• at least one external peripheral reinforcing element creating a plurality of localized zones on the outside surface of said tubular wall, the radial distance between the outside surface of the pipe and the longitudinal axis of said tubular wall in said localized zones being greater than the outside radius of tubular wall portions lying between said localized zones in a longitudinal direction, two successive ones of said localized zones being spaced apart in said longitudinal direction of said tubular wall by a distance equal to ½ to 4 times the outside diameter of said tubular wall portions, said successive localized zones being spaced apart regularly;
• and
• at least two coaxial helical reinforcing elements that are mutually parallel such that the at least two coaxial helical reinforcing elements constitute respective ones of said localized zones that are diametrically opposite about the axis of said tubular wall, respectively on each of said two helical elements.

A reinforced undersea unit pipe element suitable for transporting fluids flowing out in said pipe and suitable for being laid empty and to rest on the seabed at depths in excess of 1000 m, the reinforced undersea unit pipe element comprising:

• a tubular wall comprising at least one external peripheral reinforcing element creating a plurality of localized zones on the outside surface of said tubular wall, the radial distance between the outside surface of the pipe and the longitudinal axis of said tubular wall in said localized zones being greater than the outside radius of tubular wall portions lying between said localized zones in a longitudinal direction, two successive ones of said localized zones being spaced apart in said longitudinal direction of said tubular wall by a distance equal to ½ to 4 times the outside diameter of said tubular wall portions, said successive localized zones being spaced apart regularly;
• at least one continuous helical reinforcing element disposed in a central portion of the pipe;
• and
• at least one annular reinforcing element that is discontinuously situated between at least one end of said pipe and said continuous helical reinforcing element.