Currently, ships for the transportation of liquefied natural gas have a hold in which a coating is realised suitable for thermally insulating and containing the liquefied gas.

Generally, the coating comprises, in succession from the outside to the inside, a first layer of boxes made from rigidifie marine ply with an inner grid forming cells containing expanded perlite treated with silicon, a first watertight metallic membrane, a second layer the same as the first but of different thickness, and finally a second watertight metallic membrane.

To carry out the laying of the coating a scaffolding is used which, during laying, is distanced from the inner surface of the hold by an amount compatible with the thickness of the coating being laid or with the treatments foreseen in the various laying steps.

In particular it is necessary to be able to modify the length of the support legs of the structure, when they are raised from the base of the hold and rested above the base coating of the hold.

Conventional scaffolding is unsuitable in this case because it is not very flexible to take up variable shapes and sizes as the assembly of the coating proceeds.

Conventional scaffolding is also entirely assembled inside the ship's hold, which requires the availability and concentration inside the hold of both all of the personnel in charge of assembly and all of the necessary machinery, for example gantry cranes, cranes, conveyors and the like, which sometimes are extremely bulky.

The logistics in the transportation and storing of components, assembly and disassembly of the scaffolding, creating the coating, are necessarily complicated by the need to realise the entire operation in situ and to coordinate the realisation of the scaffolding with the construction of the ship when the two operations are rigged simultaneously.

All of this can also increase the difficulties in assembly and produce a prolongation of the times and overall a worsening of the coating costs of the hold.

Moreover, conventional scaffolding is not always susceptible to repeated and continuous assembly and disassembly with extreme practicality, simplicity, speed and safety, at the same time ensuring the integrity of the coating being 1 aid which is sometimes extremely delicate.

Finally, conventional scaffolding does not always manage to completely marry the requirement of flexibility on the one hand with the need to create a structure that is extremely stable and strong in every configuration and/or size on the other.

The technical task proposed of tine present invention is, therefore, that of realising a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which allow the aforementioned technical drawbacks of the prior art to be eliminated.

In this technical task a purpose of the invention is that of realising a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which are extremely flexible for the assembly and disassembly of the scaffolding and for the laying of the coating.

Another purpose of the invention is that of realising a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which allow the assembly and disassembly and the laying of the coating of the hold to be carried out independently of the building steps of the ship.

A further purpose of the present invention is that of providing a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which simplify the logistics in the transportation and storage of components, rigging and dismantling of the scaffolding, and laying of the coating.

Yet another purpose of the present invention is that of offering a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which optimise the use of human resources and materials necessary for the construction and dismantling of the scaffolding and for the laying of the coating.

A further purpose of the present invention is that of providing a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which allow an optimisation of the times for the construction and dismantling of the scaffolding and for the laying of the coating and a saving in costs inherent to such operations.

Another purpose of the present invention is that of realising a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which allow repeated and continuous assembly and disassembly of the scaffolding to be carried out with extreme practicality, simplicity, speed and safety, at the same time ensuring the integrity of the coating being laid.

The last but not least purpose of the present invention is that of realising a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and a scaffolding structure which manage to completely marry the requirement of flexibility on the one hand with the need to provide a structure that is extremely stable and strong in every configuration and/or size on the other.

The technical task, as well as these and other purposes, according to the present invention, are accomplished by realising a process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas, characterised in that polygonal modules of said structure are assembled in blocks outside of said hold, and then said blocks are assembled together inside said hold.

The present invention also discloses a scaffolding structure for the coating of the hold of a ship for the transportation of liquefied natural gas, characterised in that it has assembled blocks of polygonal modules off said structure, and coupling mechanical connection means between said blocks realised through pairs of male/female connection members.

Other characteristics of the present invention are defined, moreover, in the subsequent claims.

Further characteristics and advantages of the invention shall become clearer from the description of a preferred but not exclusive embodiment of the process for the assembly of a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas and of the relative scaffolding structure according to the finding, illustrated for indicating and not limiting purposes also with reference to the attached drawings, in which : figure 1 shows a typical cross section of a scaffolding structure in accordance with a preferred way of realising the present invention ; figure 2 shows a typical division into blocks used for the assembly of the cross section of figure 1, in which the blocks are shown with a broken line ; figures 3a and 3b show the structure, exploded and assembled respectively, of one of the possible ways of realising the self-centring means between the blocks of the structure of figure 1 ; figure 4 illustrates a top side section view of a leg of the structure of figure 1 ; figure 5 shows a front view of one of the possible ways of realising the means which allow the horizontal sliding of the working plane in the shelter of the side surface of the hold on each of the planes of the structure of figure 1 ; figure 6 shows a support leg of the structure with the system for discharging the pressure acting on the foot.

With reference to the quoted figures, a scaffolding structure for the laying of the coating of the hold of a ship for the transportation of liquefied natural gas is shown, wholly indicated with reference numeral 1.

The structure of the scaffolding 1 consists of blocks 2 in turn made up of polygonal modules.

The assembly of the modules which combine to constitute each individual block 2 advantageously takes place outside of the ship's hold 4, whereas the blocks 2 thus obtained are assembled together inside the ship's hold 4.

This offers multiple advantages.

First, it allows the assembly and disassembly of the scaffolding 1 and the laying of the coating of the hold to be carried out independently of the building steps the ship, since there remain wide manoeuvring spaces inside the ship's hold 4 which allow the two operations to even be carried out simultaneously without one hindering or impeding the other.

Secondly, it simplifies the logistics in the transportation and storage of components, rigging and dismantling of the scaffolding, and laying of the coating.

In particular, it is easier to separately manage a first yard outside of the hold 4 for the assembly of the modules which realise the blocks 2 from a second yard inside the ship's hold 4 for assembling the blocks 2.

Thirdly, it optimises the use of human and material resources necessary for the construction and dismantling of the scaffolding and for the laying of the coating, since the activities of the team of workers for the work outside of the ship's hold 4 can be better coordinated with the spatially separate activities of the team that works inside the hold 4.

Fourthly, it optimises the times for construction and dismantling of the scaffolding and for laying the coating and allows a saving in costs inherent to such operations, since the yards outside and inside can proceed simultaneously, limiting the idle times to the minimum also in the exploitation of the equipment necessary for the realisation of the operations.

The assembled blocks 2'define at least one perimetric framework 5 facing the side surface of the hold 4 for the laying of the side coating of the hold, a lower horizontal work plane 6 raised from the support base of the structure, and an apical upper horizontal work plane 3.

The perimetric framework 5 of the scaffolding 1 has at least one access space 43 to the work plane 6.

The perimetric framework 5 also has spacer means 51 from the side surface of the hold 4, comprising platforms 52 arranged at various heights and telescopically adjustable independently from each other.

Each platform 52 has support elements 53 each defined by two tubes with a circular section connected together one above the other in such a way as to allow them to be guided along a well defined axis through double sliding rollers 54 equLpped with throats 55.

The scaffolding 1 also comprises shoring means 56 suitable for counteracting possible horizontal loads acting upon it.

The shoring means 56 comprise extendable shafts 57 hinged to the scaffolding 1 and orientable perpendicularly to the surface of the hold 4 against which they are applied through relative support plates 58.

The scaffolding 1 also has a first and second plurality of opposite side longitudinal rows of height-adjustable legs 7 and 8, suitable for supporting the entire structure.

The support legs 7 and 8 of the structure are adjustable between an initial condition of maximum extension in which they rest with their feet 44 and 45 on the base surface of the hold 4, to an end condition of retraction in which they rest with their feet 44 and 45 above the coating of the base of the hold 4.

The balance ensured by the structure of the scaffolding 1, thanks to the type of assembly realised, allows, during the laying of the base coating of the hold 4, opposite pairs of rows of legs 7 and 8 to be raised in sequence until all of the feet 44 and 45 rest upon the upper surface of the coating of the base of the hold 4.

Each leg 7, 8 has, at one end, a large screw 46 with a rounded head 47 which engages in a seat 48 of the corresponding foot 44, 45.

Preferably, a different curvature is foreseen between the rounded head 47 of the leg 7, 8 and the relative seat 48 so as to limit the contact wear and to allow the foot 44, 45 to swivel to recover possible inclinations between the leg 7, 8 and the support base.

Between the leg 7, 8 and the corresponding support foot 44, 45 side jacks 49 and 50 are foreseen commanded fluidodynamically or manually through a device 60 for discharging the large screw 46 from the weight of the scaffolding and to ease the adjustment.

A pump (not illustrated) with a high precision manometer which allows highly precise reading of the real pressure on the leg 7, 8 at the moment of discharge acts integral with- the jacks 49, 50. This is to always allow the pressure at the foot 44, 45 above the coating to be monitored.

The feet 44 and 45 have a rectangular plan of a size such as to generate a contact pressure with the coating of the base of the hold 4 lower than a predetermined value.

The modules comprise elements with longitudinal extension and- straight hollow polygonal section which simplifies the correct relative positioning in the connection and/or welding- operations.

At least one first type of module 11, in particular intended- for a block 2 which makes up the perimetric framework 5, comprises a first and second upright 12 and 13 and a crosspiece 14 connected to form a"U", a first whole diagonal 15 and a second diagonal 16 realised in two half-parts 17 ani 18 welded to the first diagonal 15 and fixed to the first diagonal 15 through opposite connection plates 19 and 29 present at the intersection between the first and second. diagonal 15 and 16.

At least one second type of module 21, in particular intended for a block 2 for connection between the perimetric framework : 5 and the horizontal work plane 6 or the upper horizontal plane 3, comprises an upright 22, a crosspiece 23 and a first diagonal 24 connected triangularly, and also a second diagonal 25 suitable for connecting the corner between the upright 22 and the crosspiece 23 to an intermediate point of the first diagonal 24.

At least one third type of module 26, in particular intended for a block 2 which makes up the horizontal work plane 6 or the horizontal upper plane 3, comprises a first and second crosspiece 27 and 28 and an upright 29 connected to form a "C", a first and second diagonal 30 and 31 which connect the ends of the first crosspiece 27 to the intermediate point of the second crosspiece 28.

The structure of the scaffolding 1 has coupling mechanical connection means between the blocks 2 realised through pairs of male/female connection members 9 and 10.

The connection members 9 and 10 realise an end connection between uprights or crosspieces of adjacent blocks 2, through the insertion of a projection of the end of an element in the matching recess of the section of the adjacent element.

Advantageously, coupling locking means of each pair of connection members 9 and 10 are foreseen, preferably in the form of a transversal pin 32 arranged through transversally aligned holes 39 and 40 of the connection members 9 and 10 protected from coming apart through a relative split pin 33.

The locking means are secured to the modules through chains so as to avoid the risk of damaging the coating in the case of accidental falling.

Advantageously, self-centring means 34 between the blocks 2 are foreseen suitable for centring the blocks 2 during their assembly.

The self-centring means 34 comprise cm interposition member 35 between the male and the female of each pair of connection members 9 and 10, having at least one first portion 36 engaged with the male member 9 and a second frusto-conical or frusto-pyramidal portion 37 engaged with the female member 10.

In particular, the first portion 36 has a shape matching the male member 9 on which it is slotted, and is equipped with holes 38 aligned with the holes 39 and 40 of the connection members 9 and 10 to allow the introduction of the transversal pin 32, whereas the second part 37 extends from the first part 36 progressively tapering.

In a preferred embodiment, the second part 37 consists of two pairs of opposite converging trapezoidal plates 41 and 42 welded together.

Advantageously, the interposition members 35 have a different height for sequential coupling. This allows a limited initial number of connection points to be controlled during the first assembly step of the two blocks 2, to which the remaining connection points 9 and 10 are added only subsequently.

The operation of the scaffolding structure according to the invention is clear from tat which has been described and illustrated.

In particular the invention makes it possible to simply and quickly distance the ends of the scaffolding from the side and base surface of the hold by a predetermined amount according to the sequentiality with which the coating is laid.

The scaffolding thus conceived is susceptible to numerous modifications and variants, all of which are covered by the inventive concept ; moreover, all of the details can be replaced with technically equivalent elements.

In practice, the materials used, as well as the sizes, can be whatever according to requirements and the state of the art.