Flexible pipe body with buoyancy element and method of producing same
View Patent ↗A flexible pipe body and method of producing a flexible pipe body are disclosed. The flexible pipe body includes an inner fluid retaining layer; an armour layer provided radially outwards of the inner fluid retaining layer; and a buoyancy layer including a plurality of discrete elongate buoyancy elements provided radially outwards of the fluid retaining layer wound at a helical pitch angle equal to or more than 0 degrees and less than about 85 degrees to the longitudinal axis of the flexible pipe body.
1. A flexible pipe body, comprising:
an inner fluid retaining layer;
an armour layer provided radially outwards of the inner fluid retaining layer; and
a buoyancy layer comprising a plurality of discrete elongate buoyancy elements provided radially outwards of the fluid retaining layer wound at a helical pitch angle equal to or more than 0 degrees and less than about 85 degrees to the longitudinal axis of the flexible pipe body, and a protective outer sheath layer provided radially outwards of the plurality of discrete buoyancy elements.
2. The flexible pipe body as claimed in claim 1 , wherein each of the plurality of buoyancy elements extends along a longitudinal axis of the flexible pipe body.
3. The flexible pipe body as claimed in claim 1 , wherein each of the plurality of buoyancy elements extends in parallel to the remainder of the plurality of buoyancy elements.
4. The flexible pipe body as claimed in claim 1 , wherein the plurality of discrete buoyancy elements comprise tubes filled with a material with a density less than the density of sea water.
5. The flexible pipe body as claimed in claim 4 , wherein the tubes are filled with air or syntactic foam.
6. The flexible pipe body as claimed in claim 1 , wherein the plurality of discrete buoyancy elements comprise rods of a material with a density less than the density of sea water.
7. The flexible pipe body as claimed in claim 6 , wherein the rods comprise syntactic foam.
8. The flexible pipe body as claimed in claim 1 , wherein at least one of the plurality of discrete buoyancy elements are configured to be connectable to an external fluid source.
9. The flexible pipe body as claimed in claim 1 , wherein the plurality of discrete buoyancy elements are helically wound at a lay angle of around 20 to 30 degrees with respect to the longitudinal axis of the flexible pipe body.
10. The flexible pipe body as claimed in claim 9 , wherein the plurality of discrete buoyancy elements are helically wound, contra-helically to wound wires of an underlying layer.
11. The flexible pipe body as claimed in claim 9 , wherein the armour layer is a tensile armour layer.
12. A flexible pipe comprising the flexible pipe body as claimed in claim 9 and at least one end fitting.
13. A riser comprising at least one flexible pipe as claimed in claim 12 .
14. A method of manufacturing a flexible pipe body, comprising:
providing an inner fluid retaining layer;
providing an armour layer radially outwards of the inner fluid retaining layer; and
providing a buoyancy layer comprising a plurality of discrete elongate buoyancy elements radially outwards of the fluid retaining layer wound at a helical pitch angle equal to or more than 0 degrees and less than about 85 degrees to the longitudinal axis of the flexible ripe body, and providing a protective outer sheath layer radially outwards of the plurality of discrete buoyancy elements.