US 6,648,553 B2Granted

Load transfer unit and method for removing off-shore platform from substructure

AssigneeMarine Shuttle Operations AS

InventorGeir Rolfsnes

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Abstract

A platform topsides can be transferred from a substructure to a transporter by ballasting the transporter, locating the transporter underneath the topsides and deballasting the transporter, causing load transfer units of the transporter to lift the topsides off the substructure. Each load transfer unit comprises a compression spring which rests on a layer of particulate material located in a drum, the particulate material in turn rests on a releasable hatch-cover. The springs provide a flexible connection between the transporter and the topsides. During the deballasting of the transporter, the hatch-covers are released to suddenly let out the particulate material from the drums, thereby lowering and relieving the springs, causing a direct contact and a stiff connection between the transporter and the topsides.

Claims14

Dependent claims

A method for removing a platform topsides from a substructure by a floatable, ballastable transporter floating in the sea, the transporter is movable due to motions of the sea, comprising the following steps:

a) providing the transporter with load transfer units, each load transfer unit comprising
a drum having a hatch with a releasable hatch-cover forming a bottom of the drum, the drum is supported by the transporter,
a layer of particulate material resting on the hatch-cover,
a compression spring resting on the layer of particulate material,
a load-element which is slideable in the drum and rests on the spring, and which is adapted to contact the topsides,
b) providing the topsides with lift-brackets adapted to the load-elements,
c) ballasting the transporter and locating the transporter underneath the topsides with the load-elements of the transporter in alignment with the lift-brackets of the topsides,
d) deballasting the transporter until the load-elements contact the lift-brackets,
e) further deballasting the transporter until the springs are partly or fully compressed, the springs thereby maintain upward forces on the load-elements and ensure that contact between the load-elements and the lift-brackets is maintained during possible heave motion of the transporter,
f) releasing the hatch-covers to suddenly let out the particulate material from the drums, thereby lowering and relieving the springs, and simultaneously further deballasting the transporter, causing the lift-brackets to contact the drums, and causing the topsides to be lifted off the substructure, and
g) further deballasting the transporter until a safe distance between the topsides and the substructure is reached, and remove the transporter from the substructure.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/071,085Filed 11 Feb 2002
Priority: NO 2001 07039 Feb 2001
Published: US 2002/0108553 A115 Aug 2002
Granted: 18 Nov 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

E02B 17/00
Artificial islands mounted on piles or like supports
B63B 1/107
With multiple hulls: semi-submersibles; Small waterline area multiple hull vessels and the like, e.g. SWATH
B63B 35/003
Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for: for transporting very large loads,…
B63B 27/00
Arrangement of ship-based loading or unloading equipment for cargo or passengers