Turret for drilling or production ship

• US 5,359,957 A
• Filed: 05/28/1993
• Issued: 11/01/1994
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: Norsk Hydro Asa (Norsk Hydro)
• Original Assignee: Norsk Hydro Asa (Norsk Hydro)
• Inventors: Askestad, Sigmund
• Primary Examiner(s): Avila, Stephen P.
• Application Number:
  US08/070,348
• Time in Patent Office: 522 Days
• Field of Search: 114/230, 441/3, 441/4, 441/5
• US Class Current: 114/230.12
• CPC Class Codes: B63B 21/507 with mooring turrets

Abstract

A turret for a vessel, such as a drilling or production vessel for recovery of oil offshore, is installed in such a manner that it can rotate in a throughgoing opening or well in the hull of the vessel, and includes bearing arms which are equipped with axially and radially fitted bearing elements which act against corresponding bearing elements on the vessel. The bearing arms are connected to a substructure in the turret which provide individual suspension to and can absorb unevennesses and deformations in the bearing. A track of the axial bearing is disposed on a pedestal-like elevated area that is rigid in the axial direction. The pedestal-like elevated area is connected with the hull, mainly at the level of the neutral axis of the vessel, and the radial bearing element on the vessel is in the form of a band-like structure.

Claims

1. In a turret installed in a well in the hull of a vessel such that said turret is rotatable relative thereto, said turret including plural bearing arms supporting axial and radial bearing elements acting on corresponding respective axial and radial bearing track elements on said vessel, the improvement comprising:

said bearing arms being connected to and supported on a substructure of said turret such that each said bearing arm may be flexed individually and independently of adjacent said bearing arms, thereby enabling said bearing arms to individually absorb unevenness and deformations in said bearing elements;

said axial bearing track element being mounted on an elevated area of a pedestal structure mounted on said hull of said vessel, said pedestal structure being rigid axially of said turret; and

said radial bearing track element comprising a cylindrical band-shaped member.

2. The improvement claimed in claim 1, wherein said pedestal structure is mounted on and extends upwardly from a deck of said vessel.

3. The improvement claimed in claim 1, wherein said elevated area of said pedestal structure is at a level of the neutral axis of said vessel.

4. The improvement claimed in claim 1, wherein said pedestal structure includes an annular rigid torque box.

5. The improvement claimed in claim 4, wherein said torque box is mounted directly on a deck of said vessel.

6. The improvement claimed in claim 4, wherein said torque box is connected to a deck of said vessel by at least one annular column extending upwardly from a deck of said vessel.

7. The improvement claimed in claim 6, comprising two said columns spaced radially of each other.

8. The improvement claimed in claim 7, wherein said band-shaped member comprises a radially inner wall of said torque box.

9. The improvement claimed in claim 1, wherein said band-shaped member comprises an annular column connected with a deck of said vessel by a foundation in the form of a thin shell plate.

10. The improvement claimed in claim 9, wherein said column and said foundation are connected by a coupling.

11. The improvement claimed in claim 9, wherein said column is reinforced by ring-shaped braces.

12. The improvement claimed in claim 1, wherein both said axial and radial bearing comprise roller bearings.

13. The improvement claimed in claim 1, wherein each said bearing arm has mounted thereon a bogie, said axial bearing track element comprises two parallel rails, and each said axial bearing element comprises paris of roller bearings mounted on opposite circumferential ends of a respective said bogie and running on respective said rails.

14. The improvement claimed in claim 1, wherein said radial bearing elements comprise roller bearings mounted close together on a rigid rim connected to said bearing arms.

15. The improvement claimed in claim 1, wherein said substructure comprises a lower ring-shaped support base, a cylindrical column extending upwardly from said support base, plural vertical supports extending upwardly from said support base within said column, said bearing arms being connected to respective said vertical supports, and an upper top plate.

16. The improvement claimed in claim 15, wherein said support base has therein a chamber divided by bulkheads into separate ballast tanks.