Active hold down system for jack-up drilling unit

• US 20040067110A1
• Filed: 07/01/2003
• Published: 04/08/2004
• Est. Priority Date: 07/01/2002
• Status: Active Grant

• Current Assignee: Eugene E. Begnaud, William T. Bennett Jr
• Original Assignee: Eugene E. Begnaud, William T. Bennett Jr
• Inventors: Begnaud, Eugene E., Bennett, William T. Jr.
• Granted Patent: US 6,997,647 B2
• Time in Patent Office: Days
• US Class Current: 405/196
• CPC Class Codes: E02B 17/021 with relative movement between supporting construction and platform

Abstract

A cantilever beam of a jack-up unit is provided with constant force restraining members mounted on a deck of a jack-up unit forward from conventional hold-down cantilever beam clamp. A modified cantilever beam end plate engages a first end of constant force restraining member, which may be a hydraulic cylinder, with the second end of the hydraulic cylinder secured to movable padeye, which is releasably secured to the deck of the jack-up unit. If desired a fixed foundation may be secured to the deck to reinforce the area of attachment of a padeye to the deck. To allow extension of the cantilever beam even farther to a drill well, an extension member may be attached to the end plate between a free end of the end plate and the hydraulic cylinders.

Claims

1. An apparatus for applying a constant force to a forward end of a cantilever beam extended from a structure, the apparatus comprising:

at least one hold-down member secured to the cantilever beam a distance from the forward end and exerting a pre-determined restraining force on the cantilever beam, said force having a vertical component; and

a means for securing the hold-down member to a structure, from which the cantilever beam extends, said securing means being adapted for re-positioning in relation to the cantilever beam to facilitate variance in the restraining force applied to said cantilever beam.

2. The apparatus of claim 1, wherein said securing means comprises at least one padeye, said at least one padeye having a lower portion releasably securable to the structure and an upper portion securable to said at least one hold-down member.

3. The apparatus of claim 2, wherein said at least one padeye comprises a vertical plate, a horizontal plate secured at a right angle to the vertical plate and a plurality of chocks extending upwardly from the horizontal plate and attaching the vertical plate to the horizontal plate, and wherein said at least one hold-down member is secured to the vertical plate.

4. The apparatus of claim 3, wherein said horizontal plate is securable to the structure, from which said cantilever beam extends.

5. The apparatus of claim 1, wherein said at least one hold-down member is a hydraulic cylinder.

6. The apparatus of claim 1, further comprising a beam extension assembly detachably secured to said at least one hold-down member and to the structure, from which the cantilever beam extends.

7. The apparatus of claim 2, wherein said securing means further comprises a locked-down foundation secured to the structure and a hold-down plate mounted on top of the locked-down foundation, and wherein said at least one padeye is secured under said hold-down plate.

8. An apparatus for applying a constant restraining force on a cantilever beam extended from a deck of an offshore structure and secured to the offshore structure by a cantilever beam clamp, said beam having a forward end, the apparatus comprising:

at least one hold-down member secured to the cantilever beam forward of the cantilever beam clamp and exerting a pre-determined restraining force on the cantilever beam, said force having a vertical component; and

a means for securing the hold-down member to the deck of the offshore structure, from which the cantilever beam extends, said securing means being releasably positioned at multiple pre-determined locations along port and starboard of the offshore structure to facilitate variance in the restraining force applied to said cantilever beam.

9. The apparatus of claim 8, wherein said at least one hold-down member is activated by a constant hydraulic force.

10. The apparatus of claim 8, wherein said securing means comprises a plurality of movable padeyes.

11. The apparatus of claim 10, wherein each of said padeyes comprises a vertical plate, a horizontal plate secured at a right angle to the vertical plate and a plurality of chocks extending upwardly from the horizontal plate and attaching the vertical plate to the horizontal plate, and wherein said at least one hold-down member is secured to the vertical plate.

12. The apparatus of claim 11, further comprising a plurality of insert plates secured underside of the deck of the offshore structure, and wherein the horizontal plate of each padeye is secured to an upper surface of the deck of the offshore structure in general alignment with a corresponding insert plate.

13. The apparatus of claim 11, further comprising a plurality of fixed locked-down foundations secured to an upper surface of the deck of the offshore structure and a securing plate mounted atop of each foundation, and wherein the horizontal plates are positioned between the locked-down foundation and a corresponding securing plate.

14. The apparatus of claim 11, further comprising a cantilever beam end plate and an extension member secured to the cantilever beam end plate, said extension member engaging one end of said at least one hold-down member.

15. The apparatus of claim 11, further comprising a cantilever beam end plate and a locking link for securing one end of said at least one hold-down member to the cantilever beam.

16. The apparatus of claim 15, wherein said locking link comprises a hook-shaped first portion engaging the cantilever beam and a second portion engaging one end of said at least one hold-down member.

17. An apparatus for applying a constant restraining force on a cantilever beam extended from a deck of an offshore structure and secured to the offshore structure by a cantilever beam clamp, said beam having a forward end, the apparatus comprising:

a cantilever beam end plate secured to a free end of the cantilever beam;

at least one hold-down member secured to the cantilever beam end plate forward of the cantilever beam clamp and exerting a pre-determined restraining force on the cantilever beam, said force having a vertical component; and

a means for securing the hold-down member to the deck of the offshore structure, from which the cantilever beam extends, said securing means being releasably positioned at multiple pre-determined locations along port and starboard of the offshore structure to facilitate variance in the restraining force applied to said cantilever beam.

18. The apparatus of claim 17, wherein said means for securing said at least one hold-down member comprises a plurality of securing members, each securing member having a first portion releasably secured to the deck of the offshore structure and a second portion secured to one end of said at least one hold-down member.

19. The apparatus of claim 17, wherein said means for securing said at least one hold-down member comprises a plurality of securing members and a plurality of locked-down foundations affixed to the deck of the offshore structure, each securing member having a first portion releasably secured to a corresponding locked-down foundation and a second portion secured to one end of said at least one hold-down member.

20. The apparatus of claim 17, further comprising a cantilever beam extension member secured to the cantilever beam end plate and to said at least one hold-down member.