FI59156C - RELEASE OF THE NUTLAEGGA EN LEDNING PAO BOTTNEN AV ETT VATTENDRAG - Google Patents

Description

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Patent · oeh reglataratyralaan AraWaut utbgd och utUkrift * n pubikarad 27.02.8l (32) (33) (31) ^ 3ry4 «tjr atuoikau» —e * glr4 prloritat 26.04.73

France-France (FR) 7315169 (71) Bouygues, 3Ö1 avenue du General de Gaulle, 92140 Clamart,

Entreprise Quille, 98 avenue de Bretagne, 76015 Rouen,

France-France (FR) (72) Claude Jeantils, Neuilly S / Seine, France-France (FR) (74) Oy Kolster Ab (54) Apparatus for lowering a pipe to the bottom of a body of water

The invention relates to a device for locating a pipeline by means of a float device at the bottom of a body of water, which device comprises a plurality of long successively arranged and articulated float elements, each of which has two longitudinally spaced control and retaining devices for the pipeline. at the center and not at the joints

To lower the pipe to the bottom of a relatively long body of water, a barge is generally used to make or join the pipe sections from which the pipe is to be assembled and a longitudinal float to support the pipe from the barge and guide it wholly or partially along its landing path.

The float device can be either a beam made of strong material or a boom formed of successive elements and connected to each other by successively lockable or unlocked joints.

2 59156

There are two different types of float equipment, depending on whether the equipment is rigid (formed of continuous or successive elements locked in the operating position or capable of articulation in use).

In the former case, the float device is a stiffening boom, which is floating or not, and the lifting capacity of which can be varied, and which is connected to the barge at one end. In some embodiments, this device may press to the bottom to lower the pipes into relatively shallow waterways (less than 30 meters), but most often this device is short compared to the length of the pipe curve that follows the barge between the barge and the bottom. The rollers support and possibly enclose the tube in the cage while it slides along the float device. The function of this type of float device is that if it presses to the bottom, it should support the pipe all the way from the barge to the bottom, while if it does not press to the bottom, this boom should give the pipe a certain curvature throughout the zone where it supports the pipe. This curvature is adjusted by adjusting the curvature of the device itself. This adjustment is usually performed by giving it a predetermined curvature in the case of a rigid structure, and by locking the joints and changing the lifting capacity of the various elements of the boom in the case of a device consisting of several successive elements. The lower curvature depends only on the conditions affecting the pipe at the point where it leaves the float and further depends on the position and shape of the bottom, so this curvature can be adjusted by adjusting the pull on the pipe, the buoyancy and possibly its curvature.

In the second case, the float device is formed by a series of floating elements which are connected to each other by joints and whose lifting capacity is possibly adjustable, this device being connected at one end to the barge and at the other end pressed to the bottom of the body of water.

The rollers remain in the cages of the pipe along the entire distance that the pipe slides along the articulated support boom. The pipes always line according to the S-shaped curve. The curvature of the pipe at each point of this curve up to the bottom depends on the conditions prevailing at the point where the pipe leaves the barge, the lifting capacity of the device and the holding force caused by it. This curvature can thus be adjusted by adjusting the traction applied to the tube and possibly the lifting capacity of the float device and / or its holding force, if this is adjustable.

In the case where the float device in use is non-articulated (the former case), it is, due to its rigidity, quite sensitive to transverse stresses 3 591 56 and to some extent also to vertical stresses. The risk of this float device being interrupted by current or wave is greater the longer it is.

As a result, the use of such a float device is limited to lengths of the order of 100 meters and allows the pipe to be lowered to a maximum depth of about 200 meters.

In the case where the float device is articulated in use (the second case mentioned), it is much less sensitive to transverse or vertical stresses due to its joints, but instead is subjected to compressive "forces which tend to change its shape to" accordion-like ". To avoid this change of shape, currently known embodiments have means for restraining the float device from the bottom (sliding anchor, plow, rope, etc.).

A further disadvantage of these known embodiments is the need to use the longer the float device or its anchorage from the bottom, the deeper the pipe has to be lowered, which in practice limits the use of this type of device, as the cost becomes unreasonably high.

The object of the invention is to provide an articulated float device which has the advantages of this type of device in terms of its ability to withstand transverse stresses, but which does not have the disadvantages caused by its large length and / or its retention from the bottom.

The device according to the invention is mainly characterized in that each float element has only one float, which can be connected to the float of an adjacent float device by a single, freely pivotable joint at the end of the central longitudinal axis of the float element. the centers of the passageways of the float element are substantially equidistant from each other as the centers of the passageways of two adjacent float elements, and that the vertical planes of the centers of the passageways of two adjacent float elements intersect the two joints joining the two float elements

Suitably, similar float elements are used, and the centers of travel of each element are located at approximately a quarter or three quarters of the length of that element.

Cages with rollers are usually used as pipe support guides, in which case the rollers are distributed around the same cross-section of the pipe or around two adjacent cross-sections.

59156 k

Suitably the shortest possible joints are used so that the gap between two successive float elements is as small as possible, so that it can be assumed that the distance between the centers of travel of a given element is approximately the same as the distance between two points of the same element.

The length of the articulated float device formed according to the invention may be such that the depth of the lower end of the device is only one third or less than the depth of the water (counting from the surface).

Such a device withstands at each point the compressive forces applied to it, which are transmitted from element to element all the way to the barge, without the device twisting.

An embodiment of the device according to the invention will now be described with reference to the figures of the accompanying drawing. Some other features of the device according to the invention will become apparent from this description and the accompanying figures.

Figure 1 shows a schematic combination of a device according to the invention used for lowering a pipe.

Figure 2 shows a side view of a float element of the device according to the invention.

Figure 3 shows a detailed view and a vertical section of one end of a floating float element and an end adjacent to the next float element.

Fig. U shows the parts shown in Fig. 3 in horizontal section.

Figure 5 shows on an enlarged scale equipped with rollers uimurielementin cage at the direction of the arrow A of Figure 6 viewed from direction.

Fig. 6 shows a cage with rollers in section VI-VI in Fig. 5.

Figure 7 shows the cage with rollers of the arrow B of Figure 6 viewed in the direction.

Figures 8-10 show a beam connecting the barge to the float, seen from the side, seen from above and cut at the line X-X in Figure 9, respectively.

Fig. 11 shows the various steps that occur when lowering the pipe by means of the device according to the invention in the event that it is assumed that the operation is interrupted due to bad weather.

The figures are shown on different scales, depending on the need for illustration.

The apparatus schematically shown in Figure 1 comprises a barge 1 for lowering and possibly manufacturing a pipe to be lowered, and having a traction system of a previously known type, whereby traction can be provided either by the barge's own propulsion or by barge anchors.

This barge will not be explained in more detail because it is not within the scope of the invention, but may be of any type known in the art.

On the side opposite the direction of pull, the barge has a support beam 2, by means of which the float device 3 according to the invention is connected to the barge.

This device is shown in its position of use, where it is used to lower the pipe 1+, a part of which is already resting at the base 5 · This device is usually formed of completely similar elements.

Figures 2-7 show the characteristic details of an element of the float device 3. This element has an elongate cylindrical cavity, i.e. a float 6, with a constant lifting capacity, with a pivot joint 7 »at each end and two cages 8 with rollers located below this float at approximately a quarter and three quarters of its length. It is noted that the center of the joint 7 is located approximately on the longitudinal axis of the float 6.

Figures 3 and U show details of the joint 7. In the illustrated example, the joint is formed by a part 9 pivotally fitted via a shaft 10 to a bracket 11 connected to the end of a floating float 6 and a second part 9 'pivotally mounted to a bracket 11' connected to an adjacent float 6 by a shaft 10 '. 'near end. These two fasteners 11 and 11 'are oriented perpendicular to each other so that one of the shafts 10 and 10' is horizontal and the other of these shafts is vertical. These hinge parts 9 and 9 'are further arranged to pivot relative to each other about an axis 12 perpendicular to the axes 10 and 10' so that these three pivot axes are located in the direction of the three axes of the rectangular coordinate system.

Of course, the invention is not limited to any particular articulation structure, but any articulation that can be pivoted in all directions and function satisfactorily can be used within the scope of the invention.

Figures 5 ~ 7 show a cage with rollers in detail.

In the example shown here, the cage 8 is a structure with rollers 13 arranged around a space reserved for the passage of the pipe so that the pipe cannot deviate in a substantially different direction than the direction of its axis. In the case described here, the cage has a structure with a lower roller 13 rotating about a horizontal axis 1U, the support surface of which is V-shaped so as to support the tube, in addition, this cage has two other rollers 13 rotating about two oblique shafts 15, 59156 adapted to guide the tube from the left and right, respectively, the three axes 1H, 15 and 16 forming the base of the isosceles triangle and its two sides.

The cage structure with rollers must be opened in such a way that the float element can possibly be removed. Thus, this structure may have two parts which can be opened by turning around the shaft 17, whereby these parts can be locked in the closed position by means of a locking device 18. These two parts comprise, respectively, an upper part 19 fixed to the float 6, which supports rollers arranged on inclined shafts for lateral guide of the pipe, and a lower part 20 pivotally fixed via the shaft 17 to the upper part, on which a support roller with a horizontal axis is arranged. The guide rollers on the sides are arranged on steel or rubber springs so that they can deviate in the radial direction.

Without departing from the scope of the invention, the number of rollers and their arrangement as well as the means used to open the cage can be changed. In some cases, cages that cannot be opened may be used.

The float device 3 is formed of successive float elements which are articulated as close to each other as possible. By way of example, the length of each float element may be of the order of 12 meters, and the length of the device formed by the end-connected elements may be of the order of 260 meters.

The buoyancy of the float device per running meter is on the order of at least three times the apparent weight of the pipe, which makes it known that the minimum radius of curvature of the lower arc of the pipe is much larger (figure) than the minimum radius of curvature of its upper arc. The possible rupture of the pipe thus always takes place at the upper end, only at a depth of a few meters, i.e. in a zone to which the divers always have access.

Finally, it should be noted that such a device is always positioned so that its head is directed against the wind or current direction when the boom is released into the wave, current and wind, which considerably reduces the risks of its breaking due to bad weather.

The float device is normally connected to the rear end of the barge 1 by a support beam 2, an embodiment of which is shown in detail in Figures 8-10. In this embodiment, such a rigid beam designed to allow the pipe from the rear end of the barge to go where it protrudes into the first cage of the float with rollers, an elongate metal frame one end of which is secured to the other end of the barge by a horizontal axis joint 21 and is connected to the first float element of the device 3 by a swivel joint 22 in each direction. Near this hinge point 22, the beam 2 has relief suction cups 23, in addition to which along the beam there are rollers 2k rotating on horizontal axes 25, which are mounted below the beam to feed the pipe H so that this pipe runs along the frame formed by the beam.

Figure 11 shows the different steps that occur when lowering the pipe and provided that the lowering has to be stopped due to bad weather.

This figure shows the following steps: - Barge when lowering the pipe. The feeding of the pipe sections is interrupted due to the reported incoming bad weather, and a rope with a pipe guide cone is placed in place to reinstall the float device after the weather has improved (Fig. 11a).

- The pipes are lowered by means of a rope 26 passing through the interior of the float device 3 (Fig. 11b).

- Barge during the unloading phase of the pipe (Figure 11c).

- At the end of the lowering, the float device 3 is in a horizontal position and remains attached to the tube by means of a rope 26 (Fig. 11d).

- A buoy 27 attached to the rope 26 is placed in place to mark the pipe U (Fig. 11e).

- At the end of the bad weather, the operations are started in the reverse order, i.e. in the order shown in Figures 11d, 11c, 11b and 11a.

In the drawing, the center of the joint corresponds to the axis 12. In fact, the whole joint can be considered as the center, given the relatively small dimensions of the joint compared to the length of the float element.

Claims (3)

8 59156 An apparatus for locating a pipeline {k) by means of a float device at the bottom of a body of water, the device comprising a plurality of long successively arranged and articulated float elements, each having two longitudinally spaced control and retaining devices (8) for the pipeline. not located at the center or at the joints of the float element, characterized in that each float element has only one float (6) which can be connected to the float (6 ') of an adjacent float device by a single joint at the end of the central longitudinal axis 7 of the float element each control and retaining device (8) forms a passageway (M) and is arranged so that the centers of the passageways (8,8) of the float element are substantially equidistant from each other of the passages of the passageways (8,8 ') of two adjacent float elements, and that the vertical planes of the centers of the passageways (8, 8 and 8 ', 8') of the two adjacent float elements intersect at the joint center of the joint (7) connecting the two float elements. Device according to claim 1, characterized in that the joint (7) connecting the two adjacent float elements comprises two pivotally fastened parts (9,9 ') »one of which is movably attached to the end of the float (6) of the other float element and the other to the float of the other float element (6 ') to the adjacent end so that the axes of these three turning possibilities are arranged according to the three directions of the rectangular coordinate system. Device according to Claim 1 or 2, characterized in that the individual float elements are similar and that the centers of the passageways (8, 8) of each float element are arranged on the central longitudinal axis of the float (6) at points one-quarter or three-quarters of the float ( 6) length.