Hydraulic and earth engineering – Marine structure or fabrication thereof – Floatable to site and supported by marine floor
Reexamination Certificate
1999-01-04
2001-01-09
Bagnell, David (Department: 3673)
Hydraulic and earth engineering
Marine structure or fabrication thereof
Floatable to site and supported by marine floor
C405S204000
Reexamination Certificate
active
06171028
ABSTRACT:
The invention relates to a device for lifting a sea-going structure, such as a drilling platform consisting of a superstructure and a jacket, which device consists of a flotation body, such as a boat, provided with one or more laterally slidable lifting devices.
Accordingly to an earlier proposal by applicant, such a device is embodied with at least four or more jacks, each provided with a lifting device in order to enable raising of the superstructure after navigating the jacks under this superstructure. The drawback to such a jack is the poor adaptability to swell and the relative displacement of the flotation body or flotation bodies relative to the drilling platform. This can result in uncertainties.
The invention has for its object to provide a device wherein the above stated drawbacks are obviated and it provides for this purpose a device which is distinguished in that each lifting device is provided with a coupling member for fixing onto a part of the substructure which is arranged for movement in all directions relative to the lifting device.
A coupling member according to the invention is understood to mean that a positive connection takes place between the lifting means and the substructure of the sea-going structure, wherein the freedom of movement is ensured by the omnidirectional connection between the coupling member is preferably arranged at the bottom of a pendulum arm construction, which pendulum arm construction is suspended pivotally form the lifting device. A better stability of the already lifted part is thus ensured relative to the flotation bodies, which increases safety.
In the preferred embodiment the pendulum arm construction is embodied with two arms arranged at a mutual distance, the bottom ends of which are coupled to the coupling member on either side for pivoting thereon. This results in even better stability because the pendulum arms will automatically assume the optimum position relative to each other as a consequence of the reactive force generated by the weight of the lifted part of the sea-going structure.
If the substructure of the sea-going structure is assembled from tubes, it is recommended to embody the coupling member as a clamp, for instance a shell-like clamp which, if required, can close and open hydraulically.
The invention further relates to a method for lifting a sea-going body, wherein use is made of the above stated device. The method according to the invention is distinguished in that
the flotation body is placed adjacently of the sea-going body,
the coupling member of each lifting device under the superstructure is fixed to the substructure,
the or each lifting cylinder of the lifting device is energized,
the substructure elements such as the tubes are separated,
the superstructure is lifted from the substructure and set down onto a transport vessel such as a pontoon.
The method can also be used to lift the remaining part of the sea-going structure, i.e. the substructure, once the superstructure has first been removed. This substructure has a considerable length and to this end the invention therefore proposes to fix the coupling member of each lifting device to the upper end part of the substructure,
to lift the substructure,
to release the coupling members successively in a predetermined sequence and fix them to a lower part of the substructure by relieving the lifting cylinder,
to then energize the relevant lifting cylinder again in a predetermined sequence,
to set down the raised substructure onto a transport vessel.
In this way any desired length of substructure can be gradually raised by causing the coupling members to engage repeatedly on a lower part of the substructure and subsequently moving them upward.
REFERENCES:
patent: 4556004 (1985-12-01), Lamy et al.
patent: 4854800 (1989-08-01), Frick et al.
patent: 5037241 (1991-08-01), Vaughn et al.
patent: 5800093 (1998-09-01), Khachaturian
patent: 5829919 (1998-11-01), Heerema
patent: 2345280 (1975-03-01), None
Allseas Group S.A.
Bagnell David
Singh Sunil
Zovko Mark
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