Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Submerging – raising – or manipulating line of pipe or cable...
Reexamination Certificate
2002-01-29
2004-09-28
Safavi, Michael (Department: 3673)
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Submerging, raising, or manipulating line of pipe or cable...
C405S168300
Reexamination Certificate
active
06796742
ABSTRACT:
This is a nationalization of PCT/FR00/01155, filed Apr. 28, 2000, and published in French.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the connection and laying of the successive parts of an offshore supply line from a vessel performing installation operations, particularly in very great depths of water.
It applies to any supply line intended to carry a fluid, an electrical current, optical signals or information, and in particular to rigid or flexible tubular supply lines, umbilicals and electrical cables, whose behaviour in the vertical plane of the stretch of water is completely similar whatever the transverse rigidity of the supply line, provided that the depth of the said stretch of water exceeds 500 to 600 meters; the curvature adopted by the supply line under such conditions, whatever its nature, being substantially equivalent to the mathematical curve known as a catenary curve, since the effects of the rigidity of the supply line on the resulting curvature are secondary relative to the effects of gravity under these operating conditions.
The word “vessel” means any movable floating unit adapted to allow the laying of a supply line.
2. Description of the Related Art
The connection of the supply line parts requires the already submerged supply line part to be held, the new supply line part to be presented to the end of this part, the assembly tools to be operated and the supply line to be guided for laying in the sea.
Laying apparatuses are known which comprise, on board a vessel, (A) a variable inclination support equipped with means for supporting the weight of the already submerged supply line part and keeping available within an assembly plane the above-water end of this supply line part, means for receiving a new supply line part in accordance with the longitudinal axis of laying of the supply line and bringing it into the said assembly plane, and guide means, (B) means constituting a horizontal pivot of the support on the vessel such that the support can be inclined into the appropriate inclination for the undersea laying of the supply line, (C) means for controlling the pivoting of the support and for maintaining it at the requisite inclination, (D) means for depositing the new supply line part on the support, and (E) a workstation equipped with means for performing the assembly of the two supply line parts and ancillary tasks.
Examples of such apparatuses are described, in particular, in the following patents: U.S. Pat. No. 3,680,322; U.S. Pat. No. 5,421,675; U.S. Pat. No. 5,464,307 and U.S. Pat. No. 3,860,122.
In these embodiments, the workstation is carried by the support and means are required to ensure that this station retains the appropriate attitude, which is generally a substantially horizontal position at the assembly post, whatever the inclination of the support.
This is because the inclination of the support for laying may vary in accordance with the applications, since it depends on various factors including, in particular, the nature of the piping to be laid and the depth of laying.
An apparatus is also known which comprises a supply line support and a workstation which is carried not by the support but by the vessel, the support being fixed and the means for supporting the weight of the supply line part already submerged before assembly takes place being carried by the workstation (EP 0,478,742).
SUMMARY OF THE INVENTION
One of the objects of the invention is to allow the use of a workstation carried by the vessel and not by the support, in the case of a variable inclination support, which confers numerous advantages (simplicity, efficiency, etc.).
This is achieved, in accordance with the present invention, by arranging the pivot of the support so that it intersects the longitudinal axis of laying substantially in the said plane of assembly.
Under these conditions, the situation of the workstation for working is substantially independent of the inclination of the support, and the workstation can be carried by the vessel at a specific location.
In practice, nevertheless, it may be desirable to provide the workstation with a certain freedom of movement on the vessel in order to adapt it as well as possible to the inclination of the support.
The possibility of movement may also be desirable in order to change the nature of the work and, for example, to change from an assembly operation to a coating or monitoring operation.
Finally, the possibility of movement may be desirable in order to retract the station so as not to obstruct the tilting of the support if the support has to be folded down on the deck to make allowance for sea conditions or with a view to a major movement by the vessel.
Assembly by welding is preferred, but the invention is not confined to this form of assembly. In particular, as an alternative embodiment, provision is made for assembly to be undertaken by screwing, sliding fitting or an assembly connector.
Embodiments according to the present invention also possess one or more of the following features:
means having a curvature for guiding, on the support, a continuous supply line coming from a drum,
a beam and means for adjusting and maintaining the beam in position when it is in an inclined position, the beam furthermore being equipped with means having a curvature in order to guide a continuous supply line, coming from a drum, towards the support when the beam is in this position,
the means having a curvature possess a chute,
the means having a curvature possess a pulley,
the beam has a U-shaped upper end,
the means for maintaining the beam in position possess means for locking the beam to the support which comprise a structural link, associated with a bolt,
the support is a tower of metal girders shaped to allow a displacement of the workstation through or within the support,
the workstation is displaceable on rails rigidly fixed to the vessel,
the workstation is displaceable parallel to the longitudinal axis of the vessel,
the workstation possesses a floor for the movement of personnel and a ceiling and/or a ceiling-type structure which bears necessary means for supplying power to welding heads mounted to be displaceable substantially in the assembly plane,
the workstation possesses a ceiling and a floor which have channels for the passage of the end of the submerged supply line part and of the new supply line part,
the workstation possesses a rotating turntable equipped with means for supplying power to welding heads,
the rotating turntable is carried by a ceiling of the workstation or by a ceiling-type structure,
the turntable is capable of translational displacement within the station between an operating position and a retracted position,
the workstation comprises a turntable equipped with means for carrying out the said assembly and a turntable equipped with means for carrying out coating operations on the area of assembly, these two turntables being carried by fixed ceiling-type structures or on a ceiling of the station and being displaceable so as to be capable of substitution one for the other,
the workstation possesses control means rigidly fixed to an articulated arm which is itself rigidly fixed to a fixed support,
the workstation is a cabin whose position relative to the axis of the vessel can be adjusted as a function of the inclination of the tower,
the apparatus possesses two workstations respectively equipped with means for assembly and means for carrying out coating of the assembly, these two stations being movable in order to be able to be substituted one for the other in the operating position.
The invention applies, inter alia, to the laying of a supply line consisting of rectilinear sections or strings assembled and laid by stages, each section itself being capable of comprising a plurality of basic lengths of supply line assembled in order to form a string. These basic lengths are generally 12 meters.
It is advantageous, in order to deposit a new string on the support, to use a beam adapted to support the new string and to pivot about a substantially horizontal p
Baylot Michel
Roger Pierre
Rol François-Xavier
Rueda Christian
Bouygues Offshore
Jacobson & Holman PLLC
Safavi Michael
LandOfFree
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