EP0090006B1 - Floating device and procedure for hoisting and transporting loads - Google Patents

Abstract

The device comprises two parallel groups of floats (1, 2). Each group comprises a horizontal float (3, 4) to which vertical floats (5-14) are attached through one of their ends, the other ends being attached to longitudinal beams (17, 18). The end of one group is linked to the end of the other group by means of two horizontal transversal floats (15, 16) and a box-girder (19). The longitudinal beams carry movable supporting beams (20-23) which can be placed under the load to be hoisted and transported. The supporting beams (20-23) are provided at their ends with forks which can cooperate with supports attached to the load. The ends of the support columns of the barge have a shape and a relative position identical to those of the columns of the main structure. The method comprises, amongst other operations, hoisting the load by means of the support legs thereof.

Description

The invention relates to a device for lifting and transporting a load, with adjustable buoyancy, for work at sea, said device consisting of two parallel groups of floats connected at one of their ends, each group comprising a horizontal float on which are fixed, by one of their ends, vertical floats, the other ends being fixed to longitudinal beams, one end of a group being connected to one end of the other group by a horizontal transverse float and spacers. The invention also relates to a method for implementing said device.

Work at sea and in particular the construction or maintenance of oil platforms require powerful means of transport and lifting using barges and barge cranes whose limited capacities pose problems requiring complex and expensive solutions.

French patent FR-A-2,474,992 describes an adjustable buoyancy device, according to the preamble of claim 1 allowing lifting to significant load heights exceeding the possibilities of available barge cranes. The device is in the form of a U consisting of two parallel groups of floats connected at one of their ends by a float with a horizontal axis and by partially removable spacers. The horizontal and vertical floats are ballastable. The vertical floats of a group are connected at their emerging end by spacers forming a longitudinal beam. The load is placed between the two longitudinal beams while the pumps and the control station are arranged on the spacers forming a transverse beam at the end of the groups of floats.

Such a device is used inter alia for the establishment of bridges on the columns, during the construction or dismantling of the platforms. Generally, the bridge is brought to work on barges from where it is taken up by the adjustable buoyancy device which is brought above the columns and on either side thereof. After ballasting, the bridge comes to rest on the columns.

The device described, and moreover that any lifting means, applying to the edges of the bridge or of the building element, subjects the latter to forces which require a reinforcement of the structure to avoid deformations. Generally, the structure of a bridge is designed to rest at four or more points located inside the perimeter of the bridge and which transmit all the forces to the columns. The distribution of bending moments in the structure of the bridge roughly corresponds to that of a beam resting at two non-extreme points. In the case of lifting by its edges of a fully equipped bridge, the distribution of the bending moments corresponds to that of a beam resting at its ends. The realization of a bridge structure capable of meeting both conditions leads to a non-negligible increase in manufacturing costs, due to the increase in the weight of the bridge itself.

The object of the invention is a lifting device, with adjustable buoyancy, comprising means for supporting the fully equipped bridge, which does not require a strengthening of its structure, and a method for the implementation of said device. According to the invention, the device is characterized in that the longitudinal beams carry movable transverse support beams capable of moving along their longitudinal axis to be placed under a load to be lifted and transported. A method for implementing the device is characterized by the features of claim 10.

• La figure 1 représente une vue longitudinale du dispositif selon l'invention.
• La figure 2 est une vue en plan du même dispositif.
• La figure 3 est une vue selon la coupe III III de la figure 1.
• La figure 4 est une vue selon la coupe IV IV de la figure 1.
• La figure 5 est une vue en plan et en coupe partielle d'une poutre de soutien.
• La figure 6 est une vue en coupe selon VI VI de la figure 5.
• La figure 7 est une vue selon VII de la figure 6.
• La figure 8 est une vue à plus grande échelle du détail VIII de la figure 6.
• La figure 9 est une vue selon IX de la figure 8.
• La figure 10 est une vue en coupe selon X X de la figure 8.
• La figure 11 représente une vue de côté et partiellement arrachée de la première étape du procédé de mise en oeuvre du dispositif de l'invention.
• Les figures 12 à 22 montrent les différentes étapes du procédé selon l'invention, vues selon la coupe XII XII de la figure 11.

The explanations and figures given below by way of example will make it possible to understand how the invention can be implemented.

• Figure 1 shows a longitudinal view of the device according to the invention.
• Figure 2 is a plan view of the same device.
• FIG. 3 is a view according to section III III of FIG. 1.
• FIG. 4 is a view along section IV IV of FIG. 1.
• Figure 5 is a plan view and partial section of a support beam.
• FIG. 6 is a sectional view along VI VI of FIG. 5.
• FIG. 7 is a view along VII of FIG. 6.
• FIG. 8 is an enlarged view of detail VIII of FIG. 6.
• FIG. 9 is a view along IX of FIG. 8.
• FIG. 10 is a sectional view along XX of FIG. 8.
• FIG. 11 represents a side view and partially cut away of the first step of the method of implementing the device of the invention.
• FIGS. 12 to 22 show the different stages of the method according to the invention, seen according to section XII XII of FIG. 11.

Figures 1 and 2 show in longitudinal view and in plan the adjustable buoyancy device according to the invention, consisting of two parallel groups 1 and 2 of floats. Each group comprises a horizontal float 3, 4 on which are fixed by one of their ends, vertical floats 5 to 14.

The two groups are connected at one of their ends by transverse horizontal floats 15, 16, (Fig. 4). According to the embodiment shown, the floats 15 and 16 are fixed in line with the vertical floats 9 and 14 at the end and the penultimate floats 8, 13 arranged approximately at a quarter of the length of the groups relative to one end.

The vertical floats are held at their upper part by longitudinal beams 17 and 18 and by a transverse box beam 19 covering all the space between the vertical floats 13, 14, 8, 9. The box beam is fixed on the upper face longitudinal beams 17, 18. At least part of the horizontal and vertical floats are divided into compartments by watertight bulkheads (not shown) and are equipped with ballasting and drying circuits (not shown) controlling the buoyancy and attitude of the device.

In the embodiment shown, the vertical floats 7 and 12, arranged approximately at the middle part of each group, can optionally be placed in communication, on the one hand, with the sea by means consisting of valves of large diameter and , on the other hand, with the atmosphere by air purges.

When communications are ensured, the movements of the lifting device due to swell are greatly reduced.

The space between the vertical floats 5, 6, 7, 10, 11, 12 is completely free in the vertical and longitudinal direction, and the space between your floats 8.9.13.14 is free longitudinally and limited in the vertical direction by the beam box 19 and the horizontal floats 15, 16. According to the embodiment, the vertical free passage between the horizontal floats 15, 16 and the beam 19 is of the order of 15 meters and the transverse free passage, of the order 30 meters.

Along the longitudinal beams 17, 18 are arranged transverse mobile support beams 20, 21, 22, 23 capable of moving along their longitudinal axis. The beams can also be moved along the longitudinal beams 17, 18 and immobilized, by known means, in positions determined according to the dimensional characteristics of the load.

The production of the mobile support beams will be described later.

The adjustable buoyancy device according to the invention is equipped with eight anchors 27, 28 mounted at the end of cables wound on winches 24 and 25, on which it can be tanned or immobilized. The distribution of the anchors is as follows: four anchors 28 at the bow, two to port and two to starboard, and four anchors 27, aft, two to port and two to starboard. These anchors allow inter alia the transverse and longitudinal displacements of the device. The winches 24 and 25 are arranged in the box girder 19 and the port anchors 28 are controlled by the starboard winches 25 and vice versa for the starboard anchors. This arrangement allows good winding of the cables on the winches.

The box girder 19, the main function of which is to provide a rigid and non-deformable connection between the two groups of floats, is arranged on two floors as living quarters and technical premises.

According to a particularity of these premises, the box girder is completely sealed, the accesses and exits are provided only on the upper part or roof of the beam. Known means, such as ladders and / or stairs, connect the roof to the longitudinal beams 17, 18.

The movable support beams 20, 21, 22, 23 shown in FIGS. 5, 6, 7 consist of an arm 26 formed of a rectangular box structure 29 having a prismatic end 30 provided with a fork 31. This arm slides longitudinally between the branches of a stirrup 32 on a sole 33 made, for example, of an antifriction bronze. Support and friction pads 34 fixed to a cross 35 connecting the end of the stirrup arms, take up the tilting forces of the arm. At the upper part of the arm is fixed a rack 36 cooperating with a pinion 37 mounted at the end of the shaft of a motor 38 fixed to the cross-member 35. The control of this motor allows the movement of the arm 26 and its positioning under means supports 39 fixed to the load. The fingers 311, 312 of the fork 31 carry supports 40, 41, elastic, formed in known manner of alternating layers of elastomer and metal sheets vulcanized together. The role of these supports will be specified later.

The supports 40, 41 come into contact with the supports 39 (Fig. 6) fixed to the load.

Figures 8, 9, 10 show on a larger scale different views of detail VIII of Figure 6. The deck of the platform of which a part of the elements is shown in broken lines, consists of main beams bearing on load-bearing legs 42 The main beams carry legs intended to serve as support for the structure of the bridge when it rests on the columns of the marine structure or "jacket". To facilitate the positioning of the legs on the columns, a cylindrical-conical centering piece 43 is fixed to the end of the legs and is capable of engaging in the tubes which form the columns of the jacket.

In order to allow the lifting of the bridge by its legs, there is provided a support 39 forming a U whose transverse branch 44 carries a central bore 45 capable of receiving the tuble 42. The lateral branches 46, 47 of the U are, seen in elevation , triangular, and form vis-à-vis the transverse branch 44 of the reinforcement gussets which take up the forces exerted at the ends of said branch. The support 39 is welded perpendicularly to the tube 42 along its central bore and, by its lateral branches, along a generatrix of the tube. The branch 44 forms two cross members of sufficient length to rest on the gains 40, 41 of the fork 31. The elastic supports 40, 41 act as shock absorbers and avoid violent shocks which could occur during lifting and / or the positioning of the bridge giving it a certain degree of freedom in the transverse direction (shown by the arrow Fig. 9).

The lifting and transport device, according to an exemplary embodiment of the invention, has a length overall width of 61 meters, overall width of 41 meters and height of 19 meters with longitudinal beams and 24 meters with box girder. It is capable of transporting and lifting a load of around 2,000 tonnes. The living quarters are planned for 80 men.

The method for implementing the lifting and transport device, according to the invention, is described with respect to a load, which, according to one example, is represented by a fully equipped platform bridge, either of installations for use dwellings, either technical drilling or operating installations.

Figures 11 to 22 show the different stages of lifting and placing a bridge on the columns of the marine structure.

Figures 11 and 12 show, in elevation and in section, the arrival of the barge 50 supporting the bridge 51. The barge enters from the rear of the lifting and transport device between the groups of floats 1, 2, the support beams 20, 21, 22, 23 being retracted outward in the direction of the arrow. The ballasting of the barge is such that it allows it to pass freely under the box girder 19. The bridge is maintained on the barge, in known manner, the ends of the legs of the bridge cooperating with support columns forming part of '' a lattice structure attached to the deck of the barge. The ends of the support columns of the barge have a shape and a relative position identical to those of the columns of the marine structure or "jacket". The height of the columns is provided so that, under the buoyancy conditions defined above, the structure of the bridge is at a level higher than that of the support beams 20, 21, 22, 23. The support beams are removed ( Fig. 13) inwards, in the direction of the arrows, so as to bring the forks 31 under the supports 39 fixed to the legs of the bridge. The two previous operations are carried out without modifying the ballasting of the barge and the lifting device. The device is unballasted to increase its buoyancy and bring the forks 31 and the supports 39 into contact (Fig. 14). Deballasting is continued so that the load rests entirely on the support beams via the forks 31 and the supports 39 (Fig. 15). Deballasting is continued to completely disengage the barge 50 (Fig. 16) and evacuate it either towards the front or towards the rear of the device. The device carrying the load is towed to the installation site (Fig. 17) and, after possible deballasting, is placed above the structure to support the load, i.e. above the columns of marine structure 52 (Fig. 18). The load is positioned exactly below the columns by the operations of the device on its anchors. The device is ballasted until the legs of the bridge come into contact with the columns of the structure (Fig. 19) and continued (Fig. 20) until the weight of the load is transferred to the columns. The support beams are retracted outwards in the direction of the arrows (Fig. 21) and the device is released from the platform.

During the operations preparing the transfer of load from the transport barge to the device or from the device to the marine structure, the vertical floats (7, 12) of the middle of the device are preferably placed in communication with the sea to reduce the effects of the swell, the residual movements being absorbed by the elastic supports placed on the forks of the support beams.

The device according to the invention therefore allows, in a simple manner and without immobilization of significant resources, the fitting or removal of the deck, equipped or not, on marine structures with columns of the "jacket" type or other and, consequently, changing the destination of a platform, provided that these supports have the same relative positions and shapes.

Claims (11)

1. Load lifting and transport device with adjustable buoyancy for operations at sea, said device consisting of two parallel groups of floats connected at one of their ends, each group comprising a horizontal float (3,4) to which vertical floats (5, 14) are fixed by one of their ends, the other ends being fixed to longitudinal beams (17, 18), one end of one group being connected to one end of the other group by a transverse horizontal float (15) and a distance element, characterised in that the longitudinal beams (17,18) carry movable transverse support beams (20, 23) adapted to move along their longitudinal axis to be positioned beneath a load to be lifted and transported.

2. Device according to Claim 1, characterised in that the movable support beams (20, 23) carry, at their end facing the inside of the device, forks (31) adapted to cooperate with brackets (39) attached to the load.

3. Device according to Claim 1 or 2, characterised in that the brackets (39) consist of two crossmembers fixed at right angles to the tubes forming the legs of the deck and sufficiently long to cooperate with the dogs (311-312) of the forks (31).

4. Device according to any of claims 1 to 3, characterised in that the ends of the supporting columns of a barge are identical in shape and in relative position to those of the columns of the marine structure onto which the deck is required to be placed.

5. Device according to any of Claims 1 to 4, characterised in that the members of the forks carry at their upper part (40, 41) elastic rests cooperating with the brackets (39) attached to the load.

6. Device according to any of the previous claims, characterised in that the supporting beams (20. 23) consists of an arm (26) formed by a parallelepipedic caisson structure (29) exhibiting a prismatic end (30) fitted with a fork (31 with a stirrup (32) between the members of which the arm slides longitudinally, a sole-plate (33) and bearing and friction shoes (34) fixed respectively to the lower transverse part of the stirrup and to a cross-member (35) connecting the ends of the members of the stirrup permitting the movement and the maintenance of the arm. a rack (36) fixed longitudinally on the arm. a motor (38) carrying at the end of its shaft a pinion (37) cooperating with the rack to actuate the longitudinal movements of the arm.

7. Device according to any of the previous claims, characterised in that a vertical float (7, 12) placed approximately at the median part of each group (1, 2) comprises means to place it in communication with the sea and the atmosphere.

8. Device according to any of the previous claims, characterised in that the distance element connecting the two parallel groups of floats consists of a caisson (19) fixed to the summit of the longitudinal beams (17, 18) to leave a free passage in the longitudinal direction of the device.

9. Device according to Claim 8, characterised in that it also comprises, to connect the two groups of floats by one of their ends, two transverse horizontal floats (15,16) fixed in line with the last (9,14) and penultimate (8, 13) vertical floats.

10. Method of using the lifting and transport device according to any of the previous claims, characterised in that :

a) the load (51), the weight of which is absorbed by legs supported by a barge (50), is brought up behind the device between the groups of floats, the supporting beams (20, 23) being retracted outwards and the ballasting of the barge being such that the bows of the barge pass freely beneath the caisson beam ;

b) the supporting beams are extended inwards to bring the forks beneath the brackets (39) attached to the legs of the load ;

c) the device is deballasted to increase its buoyancy and bring the forks and the brackets into contact ;

d) the deballasting is continued to make the entire load rest upon the supporting beams ;

e) the deballasting is continued to disengage the load totally from the barge ;

f) the barge is moved clear by the front or the rear of the device ;

- operations a) to f) being performed without modifying the buoyancy of the barge -

g) the device is towed to the load transfer site and the device is positioned above the works required to support the load ;

h) the load is positioned by means of its anchors ;

i) the device is ballasted until the legs of the load are in contact with the works, this being continued until the transfer of the load to the works ;

j) the supporting beams are retracted inwards ;

k) the device is disengaged from the works.

11. Method according to Claim 10, characterised in that at least during operations c), d), e) and i), j), the vertical floats placed approximately at the median part of each group are placed in communication with the sea and the atmosphere.

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