AU2014255537B2

AU2014255537B2 - Equipment for carrying out maintenance and/or inspection operations inside a tank and method for installing such equipment

Info

Publication number: AU2014255537B2
Application number: AU2014255537A
Authority: AU
Inventors: Benjamin CHARPENTIER; Romain CLEMONT; Catalina VENAULT; Alain Virgl
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2013-04-15
Filing date: 2014-04-10
Publication date: 2017-05-25
Anticipated expiration: 2034-04-10
Also published as: FR3004432A1; AU2014255537A1; EP2986425B1; FR3004432B1; KR20150143665A; MY173562A; WO2014170587A1; CN105142864B; KR102164854B1; CN105142864A; EP2986425A1

Abstract

The invention relates to a ready‑to‑install assembly for producing an item of equipment intended to carry out maintenance and/or inspection operations inside a tank (1) having an upper wall provided with an opening (2), said assembly comprising: a set of elements intended to form a support column supporting an articulated arm (5), said set comprising: - at least one extension element (8a, 8b, 8c), - a first end‑of‑column element (7) bearing said articulated arm (5); - a second end‑of‑column element (9) bearing a connecting flange designed to attach the column to the periphery of the opening (2); and - a flange to assist with installation comprising anchor members intended to interact with the periphery of the opening (2) in the tank (1), said installation-assistance flange being equipped with a first temporary fastener, in which the extension element (8a, 8b, 8c) and the first end‑of‑column element (7) are each equipped with a second temporary fastener able to interact with the first temporary fastener of the installation-assistance flange so as to allow the first end‑of‑column element (7) and the extension element (8a, 8b, 8c) to be secured temporarily to the installation‑assistance flange while the ready‑to‑install assembly is being installed.

Description

1

EQUIPMENT FOR CARRYING OUT MAINTENANCE AND/OR INSPECTION OPERATIONS INSIDE A TANK AND METHOD FOR INSTALLING SUCH

EQUIPMENT

Technical field 5 The invention relates to tank maintenance and/or inspection equipment and concerns, notably, the maintenance and inspection of the tanks of merchant ships used for transporting liquefied natural gas.

More particularly, the invention concerns equipment for carrying out maintenance and/or inspection operations inside a tank and a method for installing 10 such equipment.

Prior art

The tanks of merchant ships regularly undergo maintenance or inspection operations, such as cleaning, welding, testing or leak detection operations.

To perform these maintenance and inspection operations, there is a known is way of fastening maintenance tools, platforms for transporting technicians, or inspection tools such as cameras to the ends of an articulated arm. The articulated arm can move inside the tank in such a way that its end can move near the various walls of the tank.

Generally, in order to access the inside of a tank and perform these 2 0 maintenance and inspection operations, an opening is made in an upper wall of the tank. This opening passes through the double hull system of the ship and opens on the ship’s deck. In the case of a floating storage and regasification unit (FSRU) or a floating production and storage and offloading unit (FPSO), a ceiling for supporting equipment is located above the ship’s deck and forms a restricted space above the 25 opening. Access to the opening is therefore relatively difficult.

Thus the process of introducing maintenance and inspection equipment into the tank through the opening formed in the upper wall of the tank is particularly complicated. 2

Summary

The invention is based on the idea of providing a ready-to-install kit for constructing equipment for carrying out maintenance and/or inspection operations in a tank, which is simple and reliable and can be introduced into the tank through a 5 small space.

According to one embodiment, the invention provides a ready-to-install kit for constructing equipment for carrying out maintenance and/or inspection operations inside a tank having an upper wall provided with an opening , said kit comprising: 10 - a set of elements intended to form a support column of an articulated arm, said set comprising: - at least one extension element having a first end provided with a first attachment member and a second end provided with a second attachment member, is - a first column end element carrying said articulated arm, said first column end element having an end provided with an attachment member capable of interacting with the first attachment member of an extension element in order to fix the first column end element to an extension element; 20 - a second column end element having a first end provided with an attachment member capable of interacting with the second attachment member of an extension element in order to fix the second column end element to an extension element and a second end carrying a fastening flange arranged to fasten the column to the periphery of the opening; and 25 - an installation assistance flange, comprising securing members intended to interact with the periphery of the opening in the tank, said installation assistance flange being equipped with a first temporary fastening member, wherein the extension element and the first column end element are each fitted with a second temporary fastening member capable of interacting with the first temporary 30 fastening member of the installation assistance flange so as to provide a temporary fastening of the first column end element and of the extension element to the installation assistance flange, during the installation of the ready-to-install kit. 3 A ready-to-install kit of this type is relatively simple to assemble. Furthermore, this kit can be installed in a limited space, since the support column of the articulated arm is composed of a plurality of sections which are introduced into the tank as the assembly progresses. 5 According to embodiments, this ready-to-install kit may have one or more of the following characteristics: - The ready-to-install kit has a plurality of modular extension elements, said first and second attachment members of an extension element being capable of interacting, respectively, with the second and first attachment members of the 10 other extension elements, so as to allow an extension element to be fixed to one or more adjacent modular extension elements.

The first temporary fastening member of the installation assistance flange comprises a pin fitted movably on the installation assistance flange, and the second temporary fastening members of the extension element and of the first is column end element comprise, in each case, an aperture for receiving said pin. The aperture for receiving the pin is an oblong aperture.

The aperture for receiving the pin is formed in the extension element, near its second end. - The extension element comprises a frame extending longitudinally between its 20 first and second ends, the first and second attachment members of said extension element being carried by a connecting element which is movable, relative to said frame, along the longitudinal direction of the frame, the second column end element comprising a pulling device capable of exerting a pull on the attachment member of the first end of the second column end element in the 25 direction of the second end of said second column end element, so as to allow a reduction of the play in the articulated arm support column when the extension element and the first and second column end elements are fixed to one another. - The second column end element comprises a frame, the pulling device comprising a rod, movable relative to said frame, which has a first end carrying 30 the attachment member of the second column end element and a second end interacting with a screw and nut system and/or an actuator capable of moving said second end translationally. 4

The extension element comprises a device for tensioning the connecting element, arranged so as to exert a pulling force on the connecting element toward the second end of said extension element.

The extension element and the first and second column end elements each 5 have a hollow frame to allow the passage of a person and/or an electrical and/or hydraulic and/or pneumatic supply line for the articulated arm.

According to one embodiment, the invention also relates to equipment comprising a ready-to-install kit of the aforementioned type in an installed state, in 10 which the installation assistance flange is installed on the periphery of an opening in an upper wall of a tank, the first column end element, the second column end element and at least one extension element being fixed to one another, and the fastening flange of the second column end element is fastened at the periphery of the opening. 15 According to one embodiment, the invention also proposes a method for assembling an aforementioned ready-to-install kit, on a tank having an upper wall provided with an opening, said method comprising, in succession: securing the installation assistance flange to the upper wall of the tank, at the periphery of its opening ; 20 - introducing the first column end element into the tank, through the opening, and fastening the first column end element to the installation assistance flange, using the first temporary fastening member of the installation assistance flange and the second temporary fastening member of the first column end element; 25 - fixing an extension element to the first column end element, using the first attachment member of the extension element and the attachment member of the first column end element; releasing the fastening of the first column end element to the installation assistance flange; 30 - introducing the extension element, fixed to the first column end element, into the tank, through the opening, and fastening said extension element to the installation assistance flange, using the first temporary fastening member of the installation assistance flange and the second temporary fastening member of the extension element; 5 - fixing the second column end element to the extension element fastened to the installation assistance flange, using the attachment member of the second column end element and the second attachment member of the extension element; 5 - releasing the fastening of the extension element which is fastened to the installation assistance flange; - fastening the fastening flange to the periphery of the opening in the tank.

In one embodiment, the fastening flange of the second column end element 10 is lowered to bear on the installation assistance flange.

In one embodiment, the assembly method further comprises, after the fastening of the extension element to the installation assistance flange, the following sequence of steps, carried out one or more times: - fixing a subsequent extension element to a previous extension is element; - releasing the fastening of the previous extension element; - introducing the subsequent extension element into the tank, through the opening, and fastening said subsequent extension element to the installation assistance flange, using the second temporary fastening member of 2 0 the subsequent extension element.

In one embodiment, the method further comprises a step of reducing the play in the support column of an articulated arm, in which step an upward pulling force is applied to the attachment member of the first column end element. 6

Brief description of the drawings

The invention will be better understood and other objects, details, characteristics and advantages thereof will be more fully apparent from the following description of some specific embodiments of the invention, provided solely for 5 illustrative purposes and in a non-limiting way, with reference to the attached drawings. • Figure 1 is a schematic view of a tank provided with an opening formed in an upper wall, and with equipment for carrying out maintenance and/or inspection operations, in an installed state, inside the tank. ίο · Figures 2 to 8 are perspective views showing the successive steps of the method of assembling said equipment; • Figure 9 is a sectional view of one of the extension elements of a support column of an articulated arm; • Figure 10 is a perspective rendering showing the upper end of the is support column and its fastening to the tank at the periphery of the opening; • Figure 11 is a sectional view of the upper end of the support column shown in Figure 10; • Figure 12 is a detailed view of Figure 10, showing a device for tensioning an extension element. 20 Detailed description of embodiments

Figure 1 shows, schematically, a tank 1 for storing and/or carrying a fluid such as liquefied natural gas. The tank 1 has an opening 2 which is formed in an upper wall 3. In some tanks 1, this opening 2 serves, when the tank 1 is filled with liquefied natural gas, to collect the gases evaporated in the tank 1 in order to convey 25 them toward a reliquefaction installation or a burner. A tank 1 of this type may form part of a land-based storage installation, for storing LNG for example, or may be installed in a floating structure in coastal or deep waters, notably in a gas carrier ship, a floating storage and regasification unit (FSRU), a floating production and storage and offloading unit (FPSO), or others. 30 Equipment 4 for maintenance and/or inspection is placed inside the tank 1 and fastened to the wall 3 at the periphery of the opening 2. 7

The equipment 4 comprises an articulated arm 5, shown in Figure 1 in a folded state. The end 6 of the articulated arm 5 can receive an inspection or maintenance platform or tool, such as a camera, a cleaning apparatus or a welding apparatus, for example. The articulated arm 5 can be deployed and moved inside 5 the tank 1. An articulated arm 5 of this type is well-known to those skilled in the art, and will not be described further.

The equipment 4 also comprises a support column for the articulated arm, enabling said articulated arm 5 to be positioned, inside the tank 1, at a height such that the end 6 of the articulated arm 5 can move near the walls of the tank 1 when ίο the articulated arm 5 is deployed. By way of example, a support column of this type has a length of about 10 to 20 meters. The support column comprises a lower column end element 7 carrying said articulated arm 5, a plurality of extension elements 8a, 8b, 8c, of which there are three in the illustrated embodiment, and an upper column end element 9 carrying a fastening flange for fastening said column to is the upper wall 3. A method for assembling this equipment 4 will now be described with reference to Figures 2 to 8.

Figure 1 shows a flange 10 for assistance in the installation of the equipment 4. The flange 10 comprises a frame 11 and a securing collar 12 having a 2 0 plurality of apertures for the passage of securing screws (not shown) which are intended to interact with apertures formed on the perimeter of the opening 2. The frame 11 comprises a central opening whose shape is adapted to guide the column elements 7, 8a, 8b, 8c and 9 during their introduction into the tank 1. The frame 11 further comprises temporary fastening members for the temporary fastening of 25 column elements 7, 8a, 8b, 8c and 8d to said flange 10 during the assembly of the column. In the illustrated embodiment, the temporary fastening members comprise two pins 13a, 13b installed movably, in apertures opening into the central opening of the flange 10, between a locking position and a release position.

Subsequently, when the flange 10 has been secured to the periphery of the 30 opening 2, the lower column end element 7, which carries the articulated arm 5, can be introduced into the tank 1 through the opening 2 as shown in Figure 3. The lower column end element 7 is then fastened temporarily to the flange 10, as shown in Figure 4. For this purpose, the lower column end element 7 comprises apertures 8 (not shown) which are arranged to interact with the pins 13a, 13b. Thus the pins 13a, 13b provide, in their locking position, a temporary fastening of the lower column end element 7 to the flange 10.

The upper end of the lower column end element 7 is fitted with a plurality of 5 attachment members 15 intended to interact with complementary attachment members carried by the lower end of an adjacent extension element 8a. The lower column end element 7 is, in this case, fitted with female members 15 intended to interact with male members carried by the lower end of the adjacent extension element 8a, the female members 15 and the male members having apertures for the ίο insertion of a pin for fastening the male members 15 to the female members. Clearly, the attachment members 15 are described and illustrated here by way of example, and the use of any other type of member would be feasible. In the illustrated embodiment, the lower end of the lower column end element 7 further comprises positioning studs 16 for interaction with complementary apertures formed 15 in the lower end of the extension element 8a. Thus the extension element 8a can be fixed to the lower column end element 7, as shown in Figure 5.

The pins 13a, 13b can then be moved toward their release position, so as to release the fastening of the lower column end element 7 to the flange 10 and allow the introduction of the extension element 8a into the tank 1, followed by the 2 0 temporary fastening of the extension element 8a to the flange 10, as shown in Figure 6.

For the temporary fastening of the extension element 8a to the flange 10, the frame of the extension element 8a comprises apertures 17, notably as shown in Figure 5, capable of interacting with the pins 13a, 13b when they are in their locking 25 position.

The apertures 17 are positioned near the upper end of the extension element 8a, so that most of said extension element 8a extends inside the tank 1 when the extension element 8a is fastened to the flange 10. Additionally, the apertures 17 have an oblong shape, the longest direction of which is oriented 30 vertically. This arrangement can facilitate the movement of the pins 13a, 13b from their locking position, in which they interact with the apertures 17, toward their release position. This is because the oblong shape of the apertures allows said extension element 8a to be lifted before the pins 13a, 13b are moved toward their 9 release position, so that the forces due to the weight of the column elements acting on the pins 13a, 13b are neutralized during the movement of the pins 13a, 13b.

The upper end of the extension element 8a comprises attachment members 18, shown in Figures 5 and 6, capable of interacting with complementary 5 attachment members of the lower end of an adjacent extension element 8b. The upper end of the extension element 8a also comprises positioning studs 19 for interaction with complementary apertures formed in the lower end of the adjacent extension element 8b.

In one embodiment, the extension elements 8a, 8b, 8c are identical, and ίο the attachment members of one of the lower and upper ends of an extension element 8a, 8b, 8c are capable of interacting with the attachment members of the other lower or upper end of each of the other extension elements 8a, 8b, 8c. In this case, the lower end of each of the extension elements 8a, 8b, 8c is fitted with male members for interaction with female members 18 of complementary shape on the 15 upper end of each of the extension elements 8a, 8b, 8c, the male and female members being provided with apertures for the introduction of pins 20 for fixing the male and female members to one another. Additionally, the upper end of each of the extension elements 8a, 8b, 8c carries positioning studs 19 capable of interacting with apertures of complementary shape formed in the lower end of each of said 20 extension elements. Clearly, a reverse arrangement of the male and female members, respectively, on the upper and lower ends is also possible.

When an extension element 8a is fastened to the flange 10, a subsequent extension element 8b is then fastened to the previous extension element 8b, using the attachment members 18 described above. The pins 13a, 13b are then moved 25 toward their release position, so as to allow the release of the fastening of the previous extension element 8a to the flange 10 and the introduction of the subsequent extension element 8b into the tank 1. The subsequent extension element 8b can then be fastened to the flange 10.

These steps are carried out as many times as required for the assembly of 30 the plurality of extension elements 8a, 8b, 8c.

When the final extension element 8c has been introduced into the tank 1, through the opening 2, and fastened to the flange 10, an upper column end element 9 can be fastened to the final extension element 8c, as shown in Figure 7. For this 10 purpose, the upper 9 column end element comprises a lower end fitted with attachment members 29, shown in Figure 11, capable of interacting with the attachment members 18 of the upper end of the final extension element 8c. The attachment members 29 of the upper column end element 9 are similar to the 5 attachment members on the lower ends of the extension elements 8a, 8b, 8c.

The upper column end element 9 also comprises a terminal flange 21 at its upper end. The terminal flange 21 enables the upper column end element 9 to be fastened to the opening 2. For this purpose, the terminal flange 21 comprises a frame 23 capable of enclosing the body of the flange 10 and an annular collar 22 ίο having a plurality of apertures for the passage of screws which are not shown.

When the temporary fastening of the final extension element 8c to the flange 10 is released, the upper column end element 9 can be lowered until the annular collar 22 of the terminal flange 21 comes to rest on the annular collar 12 of the flange 10. The terminal flange 21 can then be fastened to the upper wall 3, 15 directly or via the flange 10.

Finally, when all the elements 7, 8a, 8b, 8c and 9 of the column have been assembled and fastened to the opening 2, a step of reducing the play in the column is carried out, in order to stiffen the column.

To enable the play to be reduced in this way, the attachment members 18 2 0 on the upper ends of the extension elements 8a, 8b, 8c and the attachment members 24 on their lower ends are carried by a connecting bar 25, shown in Figure 9. The connecting bar 25 is installed so as to be slidable, inside the frame of the extension elements 8a, 8b, 8c, along the longitudinal direction of said extension elements 8a, 8b, 8c. This connecting bar 25 enables a pulling force to be 25 transmitted from the attachment members 18 on the upper ends of the extension elements 8a, 8b, 8c toward the attachment members 24 on their lower ends.

The upper column end element 9 is also fitted with pulling devices capable of exerting a pull toward the top of the tank 1 on the attachment members 15 of the 30 lower column end element 7, by means of the attachment members 18, 24 and the connecting bars 25 of the extension elements 8a, 8b, 8c, in order to reduce the play between the column elements 7, 8a, 8b, 8c, 9. 11 A pulling device comprises a pulling rod 28 installed so as to be slidable on the frame of the upper column end element 9 along the longitudinal direction of the column. The pulling rod 28 carries an attachment member 29 at its lower end, and interacts at its upper end with a screw and nut system 30 capable of moving the 5 pulling rod 28 translationally. In an alternative embodiment which is not shown, the pulling force on the attachment members 29 is exerted via a plurality of actuators.

It is also evident that the pulling forces may be transmitted by any other appropriate means in place of the connecting bars 25. In particular, the pulling forces can be transmitted by means of cables or link rods, for example. ίο Additionally, in the illustrated embodiment, each of the extension elements 8a, 8b, 8c comprises a tensioning device, shown in Figures 9, 10 and 11, enabling an upward pull to be exerted on the attachment means 24 of the lower ends of said extension elements 8a, 8b, 8c in the course of their assembly.

For this purpose, the connecting bar 25 is fixed to a sliding piece 26 15 movable in a slide 27 formed in the frame of each of the extension elements 8a, 8b, 8c and extending along the longitudinal direction of the frame. The end of the sliding piece 26, shown in detail in Figure 12, projects from the outside of the frame, and comprises a bore interacting with a retaining member 31. The retaining member 31 has a head 32 which interacts with a bearing plate 33 carried by the frame. The 20 retaining member is, for example, a threaded rod interacting with a thread formed in the aperture of the end of the sliding piece 26.

This tensioning device can provide a preliminary reduction in the play in the column in the course of the assembly of the extension elements 8a, 8b, 8c.

It should also be noted that the frames of the extension elements 8a, 8b, 8c 25 and the lower 7 and upper 9 column end elements are substantially in the shape of a rectangular parallelepiped. The frames of the column elements 7, 8a, 8b, 8c and 9 are hollow, and their lower and upper faces are open. Thus it is possible for personnel and/or electrical, hydraulic and/or pneumatic supply lines to pass through the articulated arm support column. 30 It should be noted that, in order to permit the passage of personnel, the frames of the extension elements 8a, 8b, 8c and the lower 7 and upper 9 column end elements carry a ladder which can be used for descending into the tank 1. The 12 frame of the extension element 8a can also be provided with a lateral opening (not shown) enabling personnel to access the inside of the tank 1.

Although the invention has been described with reference to particular embodiments, it is evidently not limited in any way to these embodiments, and 5 comprises all the technical equivalents of the means described and their combinations where these fall within the scope of the invention.

The use of the verb “to have”, “to comprise” or “to include” and any of its conjugated forms does not exclude the presence of elements or steps other than those stated in a claim. The use of the indefinite article “a” or “an” for an element or ίο a step does not exclude the presence of a plurality of such elements or steps unless otherwise specified.

In the claims, any reference symbol in brackets is not to be interpreted as a limitation of the claim.

Claims

1. A ready-to-install kit for constructing equipment for carrying out maintenance and/or inspection operations inside a tank (1) having an upper wall (3) provided with an opening (2), said kit comprising: - a set of elements intended to form a support column of an articulated arm (5), said set comprising: - at least one extension element (8a, 8b, 8c) having a first end provided with a first attachment member (24) and a second end provided with a second attachment member (18), - a first column end element (7) carrying said articulated arm (5), said first column end element (7) having an end provided with an attachment member (15) capable of interacting with the first attachment member (24) of an extension element (8a, 8b, 8c) in order to fix the first column end element (7) to an extension element (8a, 8b, 8c); - a second column end element (9) having a first end provided with an attachment member (29) capable of interacting with the second attachment member (18) of an extension element (8a, 8b, 8c) in order to fix the second column end element (9) to an extension element (8a, 8b, 8c) and a second end carrying a fastening flange (21) arranged to fasten the column to the periphery of the opening (2); and - an installation assistance flange (10), comprising securing members intended to interact with the periphery of the opening (2) in the tank (1), said installation assistance flange (10) being equipped with a first temporary fastening member (13a, 13b), wherein the extension element (8a, 8b, 8c) and the first column end element (7) are each fitted with a second temporary fastening member (17) capable of interacting with the first temporary fastening member (13a, 13b) of the installation assistance flange (10) so as to provide a temporary fastening of the first column end element (7) and of the extension element (8a, 8b, 8c) to the installation assistance flange (10), during the installation of the ready-to-install kit.

2. The ready-to-install kit as claimed in claim 1, comprising a plurality of modular extension elements (8a, 8b, 8c), said first and second attachment members (24, 18) of an extension element (8a, 8b, 8c) being capable of interacting, respectively, with the second and first attachment members (18, 24) of the other extension elements (8a, 8b, 8c), so as to allow an extension element (8a, 8b, 8c) to be fixed to one or more adjacent modular extension elements (8a, 8b, 8c).

3. The ready-to-install kit as claimed in claim 1 or 2, wherein the first temporary fastening member of the installation assistance flange (10) comprises a pin (13a, 13b) fitted movably on the installation assistance flange (10), and the second temporary fastening members of the extension element and of the first column end element comprise, in each case, an aperture (17) for receiving said pin (13a, 13b).

4. The ready-to-install kit as claimed in claim 3, wherein the aperture (17) for receiving the pin is an oblong aperture.

5. The ready-to-install kit as claimed in claim 4, wherein the aperture (17) for receiving the pin is formed, in the extension element (8a, 8b, 8c), near the second end of this element.

6. The ready-to-install kit as claimed in any of claims 1 to 5, wherein the extension element (8a, 8b, 8c) comprises a frame extending longitudinally between its first and second ends, the first and second attachment members (24, 18) of said extension element (8a, 8b, 8c) being carried by a connecting element (25) which is movable, relative to said frame, along the longitudinal direction of the frame, the second column end element (9) comprising a pulling device capable of exerting a pull on the attachment member (29) of the first end of the second column end element (9) in the direction of the second end of said second column end element, so as to allow a reduction of the play in the articulated arm support column when the extension element (8a, 8b, 8c) and the first and second column end elements (7, 9) are fixed to one another.

7. The ready-to-install kit as claimed in claim 6, wherein the second column end element (9) comprises a frame, the pulling device comprising a rod (28), movable relative to said frame, which has a first end carrying the attachment member (29) of the second column end element (9) and a second end interacting with a screw and nut system (30) and/or an actuator capable of moving said second end translationally.

8. The ready-to-install kit as claimed in claim 6 or 7, wherein the extension element (8a, 8b, 8c) comprises a device (26, 27, 21, 32, 33) for tensioning the connecting element (25), arranged so as to exert a pulling force on the connecting element (25) toward the second end of said extension element.

9. The ready-to-install kit as claimed in any of claims 1 to 8, wherein the extension element (8a, 8b, 8c) and the first and second column end elements (7, 9) each have a hollow frame to allow the passage of personnel and/or an electrical and/or hydraulic and/or pneumatic supply line for the articulated arm (5).

10. Equipment for carrying out maintenance and/or inspection operations, comprising a ready-to-install kit as claimed in any of claims 1 to 9, in an installed state, in which the installation assistance flange (10) is installed on the periphery of an opening (2) in an upper wall (3) of a tank (1), the first column end element (7), the second column end element (9) and at least one extension element (8a, 8b, 8c) being fixed to one another, and the fastening flange (21) of the second column end element is fastened at the periphery of the opening (2).

11. A method for assembling a ready-to-install kit as claimed in any of claims 1 to 9, on a tank (1) having an upper wall (3) provided with an opening (2), said method comprising, in succession: - securing the installation assistance flange (10) to the periphery of the opening (2) of the tank (1); - introducing the first column end element (7) into the tank (1), through the opening (2), and fastening the first column end element (7) to the installation assistance flange (10), using the first temporary fastening member (13a, 13b) of the installation assistance flange (10) and the second temporary fastening member of the first column end element (7); - fixing an extension element (8a) to the first column end element (7), using the first attachment member (24) of the extension element (8a) and the attachment member (15) of the first column end element (7); - releasing the fastening of the first column end element (7) to the installation assistance flange (10); - introducing the extension element (8a), fixed to the first column end element (7), into the tank (1) through the opening (2), and fastening said extension element (8) to the installation assistance flange (10), using the first temporary fastening member (13a, 13b) of the installation assistance flange (10) and the second temporary fastening member (17) of the extension element (8a, 8b, 8c); - fixing the second column end element (9) to the extension element (8a, 8b, 8c) fastened to the installation assistance flange (10), using the attachment member (29) of the second column end element (9) and the second attachment member (18) of the extension element (8a, 8b, 8c); - releasing the fastening of the extension element (8a, 8b, 8c) which is fastened to the installation assistance flange (10); - fastening the fastening flange (21) to the periphery of the opening (2) in the tank (1).

12. The assembly method as claimed in claim 11, further comprising, after the fastening of the extension element (8a) to the installation assistance flange, the following sequence of steps, carried out one or more times: - fixing a subsequent extension element (8b, 8c) to a previous extension element (8a, 8b); - releasing the fastening of the previous extension element (8a, 8b); - introducing the subsequent extension element (8b, 8c) into the tank (1), through the opening (2), and fastening said subsequent extension element (8b, 8c) to the installation assistance flange (10), using the second temporary fastening member (13a, 13b) of the subsequent extension element (8b, 8c).

13. The assembly method as claimed in claim 11 or 12, comprising a step of reducing the play in the support column of an articulated arm (5), in which step an upward pulling force is applied to the attachment member (15) of the first column end element (7).