CN110778909B

CN110778909B - Leakage-proof wall with reinforced corrugated membrane

Info

Publication number: CN110778909B
Application number: CN201910687847.4A
Authority: CN
Inventors: 穆罕默德·萨西; 马克·布瓦约; 文森特·贝尔热; 塞巴斯蒂安·德拉诺
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2018-07-27
Filing date: 2019-07-29
Publication date: 2023-03-24
Anticipated expiration: 2039-07-29
Also published as: FR3084346B1; CN110778909A; KR20200013222A; FR3084346A1

Abstract

The present invention relates to a corrugated leakproof tank wall, a vessel for transporting cold liquid products, a method of loading or unloading a vessel and a transfer system for cold liquid products. A leak-resistant tank wall comprising a first series of corrugations and a second series of intersecting corrugations, said corrugations comprising alternating longitudinal portions and nodes formed at the intersection of two intersecting corrugations, the tank wall comprising: -a row of first undulating stiffeners arranged below the first corrugations, two first undulating stiffeners in the row being assembled in aligned position by linking members passing through the nodes, -a second undulating stiffener arranged below the second corrugations and passing through a plurality of consecutive nodes, comprising a base designed to rest on a support surface and a stiffening portion extending over the base, the stiffening portion having a uniform cross-section over the length of the second undulating stiffener, a plurality of external notches formed in the base being arranged in the nodes of the second corrugations, the linking members being housed in said notches.

Description

Leakage-proof wall with reinforced corrugated membrane

Technical Field

The present invention relates to the field of leak-proof (tight, leak-proof, sealed) tanks with corrugated metal films for storing and/or transporting fluids, and in particular to a leak-proof thermally insulated tank for liquefied gases.

In particular, the present invention relates to the field of leakproof thermally insulated tanks for storing and/or transporting liquids at cryogenic temperatures, such as tanks for transporting liquefied petroleum gas (also called LPG) at temperatures of, for example, between-50 ℃ and 0 ℃ or tanks for transporting Liquefied Natural Gas (LNG) at atmospheric pressure at about-162 ℃. These tanks may be mounted on land or on a floating structure. In the case of a floating structure, the tank may be designed for transporting or for receiving liquefied gas used as fuel for propelling the floating structure.

Background

FR-a-2936784 describes a tank with a corrugated sealing membrane which is reinforced with the help of reinforcements arranged below the corrugations, between the sealing membrane and its support, for reducing stresses in the sealing membrane caused by various factors including thermal shrinkage when the tank cools, the effect of deflection of the ship's beam and dynamic pressures due to the movement of cargo, especially due to surging.

In this can, the sealing membrane has two series of vertical corrugations. Thus, the sealing membrane has a plurality of nodes corresponding to the intersections between the corrugations in the two series of corrugations.

In one embodiment, these reinforcing portions, also called undulated (ripple, groove) reinforcements, are hollow and allow gas to flow between the corrugations and the support by passing through the reinforcing portions, in particular for inerting the insulation barrier or detecting leaks. These reinforcing portions are arranged below the corrugations, between two consecutive nodes, and are therefore discontinuous at said nodes.

Disclosure of Invention

However, the applicant has noted that the seal film stress is not necessarily uniform in the can. Thus, the same bellows may be subjected to asymmetric stresses, which may cause the membrane to deform, in which case the reinforcing portion does not sufficiently function to realize the reinforcing membrane. In particular, the applicant has noticed that the reinforcing portion, together with the corrugations housing it, may undergo a movement due to the asymmetrical stresses to which said corrugations are subjected. This movement of the reinforcing portion and corrugations together may cause the membrane to kink at the nodes.

One basic idea of the present invention is to provide a leakage preventing wall having a corrugated sealing film continuously reinforced along the corrugations. One basic idea of the invention is to ensure the continuity of the undulating stiffeners arranged in the corrugations. One basic idea of the invention is to align the undulating stiffeners arranged below the corrugations to limit the risk of kinking of the membrane at the nodes.

According to one embodiment, the present invention provides a leak-proof tank wall comprising a corrugated leak-proof membrane, which is a sealing membrane.

The leakage-proof film includes:

-a first series of corrugations, the corrugations of the first series of corrugations being parallel,

-a second series of corrugations, the corrugations of the second series of corrugations being parallel, an

A planar portion located between the corrugations of the first series of corrugations and the corrugations of the second series of corrugations, the planar portion being designed to rest on a support surface,

a corrugation of a first series of corrugations and a corrugation of a second series of corrugations extending in intersecting directions, the corrugation of the first series of corrugations and the corrugation of the second series of corrugations comprising alternating longitudinal portions and nodes formed at intersections of the corrugations of the first series of corrugations and the corrugations of the second series of corrugations,

the tank wall further comprises:

-a plurality of parallel rows of first undulating stiffeners, a row of first undulating stiffeners being arranged below a first corrugation belonging to a first series of corrugations, the first undulating stiffeners of said row being arranged below successive longitudinal portions of said first corrugation such that two successive first undulating stiffeners in said row are separated by a junction of said first corrugation, said two successive first undulating stiffeners being assembled in a position aligned below the first corrugation by a tie member passing through the junction separating said two successive first undulating stiffeners, the tie member having a smaller dimension than the undulating stiffeners in the thickness direction of the tank wall,

-a second undulating stiffener arranged below a second corrugation belonging to the second series of corrugations, the second undulating stiffener passing through a plurality of consecutive nodes of said second corrugation, said second undulating stiffener comprising a base (sole, base, bottom panel) resting on a support surface and stiffening portions extending through the base, the stiffening portions having a uniform cross-section over the length of the second undulating stiffener, a plurality of external notches (indentations, grooves, indentations) formed in the base being arranged in respective nodes of the second corrugation, coupling members passing through said nodes being housed in said corresponding notches.

By these features, continuity is ensured between two consecutive first undulating stiffeners arranged in the first corrugations on either side of and separated by a node. By these features, relative movement between two consecutive first undulating stiffeners arranged in a first corrugation is restricted, including in the presence of asymmetric stresses on either side of the junction.

Such a wall may also include one or more of the following features, depending on the embodiment.

According to an embodiment, said notches are formed on the lower wall of the second undulating stiffener so that said linking member passes through said nodes under the second undulating stiffener.

According to one embodiment, the tank wall further comprises at least one thermal insulation barrier, the support surface being an inner surface of said thermal insulation barrier.

According to one embodiment, the longitudinal portion of the corrugations in the second series of corrugations has a constant cross-section.

According to one embodiment, the junction comprises an apex, a first corrugation of the first series of corrugations forming said junction, the junction comprising, on either side of the apex, a concave portion forming a reduced portion of said first corrugation.

According to one embodiment, the corrugations of the second series of corrugations are interrupted at a junction by corrugations of the first series of corrugations with which they form said junction.

According to one embodiment, the reinforcement portion has an outer wall, for example of a semi-elliptic convex shape, defining an inner space of the reinforcement portion.

According to one embodiment, the inner space of the reinforcement part is hollow and constitutes a passage for gas to flow through the reinforcement part.

According to one embodiment, the reinforcement portion further comprises an internal reinforcement web.

According to one embodiment, the first undulating stiffener has an outer wall, for example an outer wall of a semi-elliptical convex profile, which defines an inner space of said first undulating stiffener.

According to one embodiment, the inner space of the first undulating stiffener is hollow and constitutes a passage for gas to flow through said undulating stiffener.

According to one embodiment, the first undulating stiffener further comprises an internal stiffening web.

According to one embodiment, the sealing membrane comprises a corrugated metal sheet delimited by edges.

According to one embodiment, the second corrugated reinforcing element extends from a first longitudinal portion of the second corrugation interrupted by a first edge of the corrugated metal sheet, opposite to a second edge of the corrugated metal sheet, up to a second longitudinal portion interrupted by a second edge of the corrugated metal sheet, so that said second corrugated reinforcing element passes through all the nodes of the second corrugation formed by said corrugated metal sheet.

According to one embodiment, the second contoured reinforcement passes through a plurality of nodes of the second corrugations formed by the corrugated metal sheet.

According to one embodiment, the second undulating reinforcing member passes through all the nodes of the second corrugations formed by the corrugated metal sheets.

According to one embodiment, the corrugated metal sheet is rectangular.

According to one embodiment, the corrugations of the first series of corrugations and the corrugations of the second series of corrugations are parallel to respective edges of the corrugated metal sheet.

According to one embodiment, the tank wall comprises a row of said second undulated stiffeners arranged below the second corrugations.

According to one embodiment, the tank wall comprises one or more rows of second undulating stiffeners.

According to one embodiment, the sealing membrane comprises a plurality of corrugated metal sheets welded together in a leak-tight manner.

According to one embodiment, the second undulating stiffeners of a row of second undulating stiffeners extend from a first longitudinal portion of a second corrugation interrupted by a first edge of the respective corrugated metal sheet, up to a second longitudinal portion interrupted by a second edge of said corrugated metal sheet, the first edge of said corrugated metal sheet being opposite to the second edge of said corrugated metal sheet. In other words, one, more or each second undulating stiffener of a row of second undulating stiffeners passes through all the nodes of the second corrugations formed by a respective corrugated metal sheet of the plurality of corrugated metal sheets.

According to one embodiment, two successive undulating stiffeners of a row of second undulating stiffeners are assembled by a linking bush so as to keep said second successive undulating stiffeners aligned below the second corrugations.

Thus, successive second undulating stiffeners of a row of second undulating stiffeners are kept aligned in the second corrugations by the linking bushes, so that said second corrugations are continuously supported over their length.

According to one embodiment, the ends of the second undulating stiffeners of a row of second undulating stiffeners comprise a shell having an opening facing the facing second undulating stiffener, the coupling bushings fitting in the shells of two consecutive second undulating stiffeners of a row of second undulating stiffeners.

According to one embodiment, the shell of the second contoured stiffener is formed in a sub-base of said second contoured stiffener, said sub-base having a lower surface resting on the support surface, said shell being open on the lower surface of the sub-base.

According to one embodiment, the base has a planar lower wall resting on the support surface and a planar upper wall parallel to the lower wall.

According to one embodiment, the base includes a side wall connecting the lower wall and the upper wall, the lower wall of the base, the upper wall of the base, and the side wall of the base together defining a hollow interior space of the base.

According to one embodiment, the housing comprises at least one reinforcement.

Such reinforcements may be produced in various ways. According to one embodiment, the reinforcement comprises a plurality of ribs extending from the lower wall and/or the upper wall of the base in the shell. According to one embodiment, the ribs extend perpendicularly to the upper and/or lower wall of the base.

According to one embodiment, the first contoured stiffener comprises:

-a central portion housed below a longitudinal portion of a first corrugation of the first series of corrugations, the central portion having a hollow base resting on a support surface,

two hollow attached spacers arranged on either side of the central portion, the attached spacers extending the hollow base of the central portion and extending in nodes located on either side of the longitudinal portion below which the central portion is accommodated,

the joining members assembling two successive first undulating stiffeners are housed in the hollow base of the central portion of said first undulating stiffeners and pass through the corresponding attachment spacers.

The present invention also provides, according to one embodiment, a method for installing a containment tank wall, comprising the steps of:

-arranging on the leak-tight tank supporting surface, preferably for each first corrugation of the first series of corrugations of the rectangular corrugated metal sheet of the sealing membrane, a row of first corrugated stiffeners, said row being formed by an alternating assembly of tie members and first corrugated stiffeners, for example by nesting,

-holding in place the ends of the row of first undulating stiffeners on a support surface,

-placing a second undulating stiffener on the support surface, preferably for each second corrugation of the second series of corrugations of the rectangular corrugated metal sheet, the second undulating stiffener comprising a base resting on the support surface and a stiffening portion extending through the base, the stiffening portion having a uniform cross-section over the length of the second undulating stiffener, a plurality of external recesses being formed in the base, the coupling members of a row of first undulating stiffeners being received in said corresponding recesses,

-fixing the corrugated metal sheet on the support surface such that a row of first corrugated stiffeners is received in corresponding first corrugations of the rectangular corrugated metal sheet and such that second corrugated stiffeners are received in second corrugations of the rectangular corrugated metal sheet.

According to one embodiment, the step of retaining the ends of the row of first contoured stiffeners comprises the following steps

-placing in the first corrugated stiffener a coupling member projecting from a rectangular corrugated metal sheet previously fixed to the support surface,

-sleeving a first end corrugated stiffener of a row of first corrugated stiffeners in said coupling member.

According to one embodiment, the step of retaining the ends of the row of first undulating stiffeners comprises the step of fixing a fixing rail on the support surface, said fixing rail engaging with the first end undulating stiffeners of the row of first undulating stiffeners to retain the corresponding ends of the row of first undulating stiffeners on the support surface.

According to one embodiment, a securing rail engages ends of a plurality of adjacent rows of first undulating stiffeners disposed on a support surface to secure the position of the plurality of rows of first undulating stiffeners.

According to one embodiment, the method further comprises:

-a step of fixing a fixing rail to the second undulating stiffener, said fixing rail having a through hole,

-a step of inserting, preferably sliding, the retaining bar together into the hole and into the second contoured stiffener, the retaining bar passing through the fixing track for the second contoured stiffener.

According to one embodiment, the method further comprises the step of removing the fixing rail from the support surface.

According to one embodiment, the step of anchoring the rectangular corrugated metal sheet to the support surface comprises the step of welding said rectangular corrugated metal sheet to the rectangular corrugated metal sheet previously anchored to the support surface.

Such tank walls may form part of, for example, land based storage means for storing LNG or may be installed in floating, coastal or deep water structures, especially any vessel where methane is transported to exchange or use combustible liquefied gas as fuel, floating Storage Regasification Unit (FSRU), floating production storage offloading unit (FPSO) etc.

According to one embodiment, the invention provides a ship for transporting cold liquid products comprising a double hull and a tank arranged in the double hull comprising the aforementioned leakage preventing wall.

According to one embodiment, the invention also provides a method for loading and unloading such a vessel, wherein the cold liquid product is transported from the floating or land storage to the vessel's tanks or from the vessel's tanks to the floating or land storage facility by insulated pipelines.

According to one embodiment, the invention also provides a transfer system for a cold liquid product, the system comprising a vessel as described above, an insulated pipe arranged such that the tank mounted in the hull of the vessel is connected to a floating or land storage means, and a pump to flow the cold liquid product from the floating or land storage means to the tank of the vessel or from the tank of the vessel to the floating or land storage means through the insulated pipe.

Drawings

The present invention will be better understood and other objects, details, features and advantages thereof will become more clearly apparent from the following description of several particular embodiments thereof, given by way of illustration only and not in limitation, with reference to the accompanying drawings.

Figure 1 is a view of a corrugated metal sheet designed for constructing a leak-proof membrane of a tank for storing liquefied natural gas;

FIG. 2 is a schematic perspective view from above of a net formed by large and small undulating stiffeners;

FIG. 3 is a schematic perspective view from below of a net formed by large and small undulating stiffeners;

FIG. 4 is a cross-sectional view of a small undulation stiffener at the coupling bushing;

FIGS. 5 to 9 are partial schematic perspective views of the leakproof thermal insulation tank wall in the process of mounting the leakproof film on the thermal insulation barrier;

fig. 10 is a partially schematic perspective view of the tank wall of fig. 5 to 9 when the last small undulation reinforcement is installed;

fig. 11 is a schematic illustration of a section of a tank of a methane carrier and a quay for loading/unloading the tank.

Detailed Description

By convention, the terms "outer" and "inner" are used to define the relative position of one element with respect to the other when referring to the interior and exterior of the can.

A leak-proof thermally insulated tank for storing and transporting a cryogenic fluid, such as Liquefied Natural Gas (LNG), includes a plurality of tank walls, each having a multi-layered structure.

From the outside to the inside of the tank, such a tank wall comprises: a thermal insulation barrier anchored to the load-bearing structure by a retaining member, and a sealing membrane carried by the thermal insulation barrier and designed to be in contact with the cryogenic fluid contained in the tank.

The load bearing structure may be in particular a self-supporting metal sheet or more generally any type of rigid spacer having suitable mechanical properties. The load-bearing structure may in particular be formed by the hull or double hull of a ship. The load bearing structure includes a plurality of walls defining the general shape of a tank, which is typically in the form of a polyhedron.

The can may further include a plurality of thermal insulation barriers and a sealing membrane. For example, from the exterior toward the interior of the tank, the tank may include a secondary thermal insulation barrier anchored on the load-bearing structure, a secondary sealing film carried by the secondary thermal insulation barrier, a primary thermal insulation barrier resting on the secondary sealing film, and a primary sealing film resting on the primary thermal insulation barrier. The thermal insulation barrier can be produced in various ways from various materials according to the described known art, for example the documents WO2017017337 or WO 2017006044. The sealing membrane may be constructed of a rectangular corrugated metal portion including a series of corrugations of different sizes or similar.

Fig. 1 shows a corrugated metal sheet 1 designed to form a leak-proof membrane for a tank for storing liquefied natural gas.

The metal sheet 1 comprises a second series of "bottom" parallel corrugations 2 extending in direction y and a first series of "top" parallel corrugations 3 extending in direction x. The directions x and y of these series of corrugations are perpendicular. The

corrugations

2, 3 project on one side of the inner face of the metal sheet 1, which is designed to be placed in contact with the fluid contained in the tank. The edges of the metal sheet 1 are here parallel to the

corrugations

2, 3. It should be noted that the terms "top" and "bottom" have opposite meanings, and it is to be noted that the "bottom" corrugations 2 are lower than the "top" corrugations 3.

The metal sheet 1 comprises a plurality of planar surfaces 4 between the

corrugations

2, 3. At each intersection between the bottom corrugation 2 and the top corrugation 3, the metal sheet 1 comprises a node 5. In other words, each

corrugation

2, 3 comprises a continuous longitudinal portion 6 and a node 5, said node 5 being formed by the intersection of said

corrugation

2, 3 with a

perpendicular corrugation

3, 2. Such a longitudinal portion 6 has a substantially constant cross section, the variation of the cross section of the

corrugations

2, 3 at the intersection between the

corrugations

2, 3 marking the beginning of the junction 5. However, the longitudinal portion 6 may comprise local deformations (not shown), as described in document FR 2861060.

The nodes 5 comprise folds 7 extending from the edges of the peaks 8 of the top corrugation 3. This fold 7 forms the peak of the knot 5 which projects towards the interior of the can. The edge of the crest 8 of the top corrugation 3 also comprises a pair of concave corrugations 9, the concavity of which faces the inside of the can and which are arranged on either side of the fold 7. Furthermore, the fold 7 abuts a pair of side notches 10 formed in the top corrugation 3 and crossed by the bottom corrugation 2.

Unlike the top corrugations 3, the bottom corrugations 2 have a constant cross section. This bottom corrugation of constant cross-section is interrupted by the top corrugation 3 and connected to said top corrugation 3 at the side notches 10 of the top corrugation 3.

The metal plate 1 can be made of stainless steel, aluminum or

Production, i.e. expansion coefficient, is usually 1.2.10 ^-6 To 2.10 ^-6 K ^-1 An intermediate iron-nickel alloy, or an iron alloy with a high manganese content, typically having a coefficient of expansion of about 7 to 9.10 ^-6 K ^-1 . However, other metals or alloys are also possible.

For example, the metal plate 1 has a thickness of about 1.2 mm. Other thicknesses are also conceivable, bearing in mind that the metal sheet 1 is thicker, with a consequent increase in its cost, and generally increases the stiffness of the

corrugations

2, 3.

According to an advantageous embodiment, both vertical edges of each metal sheet 1 have a stepped portion (not shown), i.e. a portion that is horizontally different, so that when the metal sheets 1 are welded together, those edges having a stepped portion each pass over (cross, cover).

Further possible details and features of the structure of the sealing membrane, the metal plates 1 forming said sealing membrane and the nodes 5 are described in documents WO2017017337 or WO 2017006044. For example, the metal plate 1 assembled to form the sealing film may be formed by stretching or bending.

The

corrugations

2, 3 of the metal plate 1 enable the sealing membrane to be flexible, so that it can be deformed by the effect of thermal and mechanical stresses generated by the liquefied natural gas stored in the tank. Undulating stiffeners are arranged in the

corrugations

2, 3 to stiffen the sealing membrane against these various stresses. More specifically, a plurality of rows of large undulation stiffeners 11 are arranged below the top corrugations 3, and are the first undulation stiffeners. Also, a plurality of rows of small-undulation reinforcing members 12 are arranged below the bottom corrugated portion 2, and the small-undulation reinforcing members are second undulation reinforcing members. These undulating

stiffeners

11, 12 make it possible to support and stiffen the

bellows

2, 3 of the sealing membrane in the presence of stresses related to the movement of the fluid in, for example, a tank.

Such undulating

stiffeners

11, 12 are shown in detail in fig. 2 to 5. In these figures 2 to 5, the sealing film is not shown, so as to make clearer the features and the arrangement of the undulating

stiffeners

11, 12, it being understood that these undulating

stiffeners

11, 12 are described in the following context: the corrugated reinforcing

members

11, 12 are arranged below the

corrugations

2, 3 of a sealing membrane formed by a plurality of corrugated metal sheets 1 as shown in fig. 1.

As shown in fig. 2 and 3, the first corrugated stiffener 11 includes a central portion 13 and two attachment spacers (spacers) 14.

The central portion 13 is hollow and comprises a lower wall 15 crossed by an outer envelope 16. The lower wall 15 and the outer envelope 16 together delimit a hollow interior space of the central portion 13 to allow a gas flow for inerting or detecting leaks in the thermal insulation barrier.

The outer envelope 16 is preferably of a form complementary to that of the top corrugation 3. Thus, as shown in fig. 2, the outer envelope 16 has a dome form, i.e., a semi-elliptic convex form.

The inner space of the central portion 13 advantageously comprises an inner web 17 to reinforce said central portion 13.

The length of the central portion 13 at the peaks of the outer envelope 16 is for example equal to the length of the longitudinal portion 6 of the top corrugation 3, which has a uniform cross section between the two nodes 5. This portion with uniform cross section ends where the top corrugation 3 has a slight lateral constriction, marking the beginning of the side notches 10, corresponding to the beginning of the nodes 5, the geometry of which is complex, as described above. Furthermore, the outer envelope 16 has an inclination opposite to the nodes 5, which substantially corresponds to the inclination of the lateral notches 10, so that the central portion 13 is as close as possible to the nodes 5, to optimize the support of the top corrugations 3.

The attachment spacer 14 is hollow and extends the bottom part of the hollow interior space of the central portion 13 in the node 5. For this purpose, the attachment spacer has a lower wall 18, two side walls 19 and an upper wall 20. Such attachment spacers 14 are arranged on both sides of the central portion 13 to lengthen said central portion 13 in two nodes 5 located on both sides of the longitudinal portion 6 housing the central portion 13.

The stress in the tank is not always uniform. Thus, the

corrugations

2, 3 may be subjected to asymmetric stresses over their length. Such asymmetric stresses cause lateral stresses to be exerted on a longitudinal portion 6 of a

corrugation

2, 3, while the longitudinal portion 6 adjacent to said

corrugation

2, 3 is not subjected to similar stresses. In the presence of such asymmetric stresses, the

corrugations

2, 3 may undergo significant kinking at the junction 5 separating two consecutive longitudinal portions 6 subjected to said asymmetric stresses.

To prevent this, the coupling structure 21 is fitted in the two continuous large undulation reinforcing members 11 of the top corrugated portion 3.

Such a coupling member 21 has a thickness, taken in the thickness direction of the tank wall, such that said coupling member 21 passes through the junctions 5 between successive highly undulating stiffeners 11. In general, the coupling member 21 has a preferably constant rectangular section, the thickness of which is less than the distance separating the thermal insulation barrier and the concave corrugations 9 of the nodes 5.

Furthermore, the opposite end 22 of the linking member 21 has a cross section of a form complementary to the bottom portion of the hollow internal space of the large undulating stiffener 11. Thus, the end 22 of the linking member 21 passes through the hollow attachment spacer 14 and is inserted into the bottom portion of the hollow interior space of the central portions 13 of the two large contoured stiffeners 11. These end portions 22 are inserted by sliding into the central portion 13 of the attachment spacer 14 and the corresponding large contoured stiffener 11. This sliding makes it possible to also fill any positioning tolerances of the large undulating stiffener 11 related to the constructional stresses of the sealing membrane.

Thus, two continuous large undulating stiffeners 11 separated by nodes 5 are aligned below the corresponding top corrugations 3 by the linking members 21 housed in said nodes 5 and fitted in said continuous large undulating stiffeners 11.

In a variant not shown, the coupling member 21 has a stop surface which engages with the attachment spacer 14 to limit the sliding of its end 22 in the large contoured stiffener 11. These stop surfaces can be produced in various ways, for example by a variation in cross section, resulting in a greater thickness or a locally greater width of the coupling member 21.

Once the linking member 21 is properly positioned, the attachment spacer 14 may be secured to the linking member 21. The attachment spacer 14 may be secured in various ways. In the embodiment shown in fig. 3, the attachment spacer 14 is riveted to the linking member 20 by a rivet 23. In one embodiment, not shown, the attachment spacer 14 is fixed to the coupling member 21 by screwing, welding or by any other suitable means.

The spacer 14 is attached so that the sliding of the central portion 13 of the large contoured reinforcement 11 below the top corrugations 3 can be limited. In particular, these attachment spacers 14 stop the movement of the central portion 13 towards the node 5, preventing the central portion 13 from contacting the sealing membrane at the node 5. This non-contact makes it possible to prevent the sealing film at the junctions 5 from deteriorating.

Furthermore, such attachment spacers 14 act to stop the central portion 13 of the large undulating stiffener 11 in position and ensure the correct positioning of the first undulating stiffener 11 on the thermal insulation barrier during the assembly of the sealing film on the thermal insulation barrier. This stop function is particularly useful in the case of tank walls with vertical components, preventing the large undulated stiffeners 11 from moving by gravity.

As shown in fig. 4, the small undulating stiffener 12 includes a sub-base 24 over which is stiffened portion 25.

The base 24 comprises a planar lower wall 26 which rests on a support surface formed by a thermal insulation barrier. The base 24 further comprises two side walls 27 and a planar upper wall 28. The upper wall 28 is parallel to the lower wall 26. The side wall 27 connects the lower wall 26 and the upper wall 28.

In the embodiment shown in fig. 4, the sub-base 24 includes reinforcements that cause the small undulating reinforcements 12 to be reinforced. These reinforcements are formed by ribs 29 extending in the sub-base 24 perpendicular to the lower surface 26 and the upper surface 28. These ribs 29 also extend parallel to each other.

The reinforcing portion 25 has an outer envelope 30 of convex form, for example dome form similar to the form of the bottom corrugation 2. The outer envelope 30 defines, together with the upper wall 28 of the sub-base 24, a hollow interior space of the reinforcement portion 25. This hollow interior of the reinforcement portion 25 allows gas flow for inerting and/or detecting leaks in a similar manner to the hollow interior of the central portion 13 of the large contoured reinforcement 11. Furthermore, the reinforcing portion 25 also comprises an internal web 17 which makes it possible to reinforce said reinforcing portion 25.

In a similar manner to the first undulating stiffeners 11, it is preferable to keep the second undulating stiffeners 12 housed under the bottom corrugations 2 aligned despite the presence of the nodes 5. However, unlike the top corrugations 3, which have a decreasing cross section with respect to the nodes 5, the bottom corrugations 2 have a constant cross section, which is interrupted at each point by the nodes 5, without the cross section decreasing.

The small undulating stiffeners 12 shown in fig. 2 and 3 pass through the nodes 5 without being interrupted by said nodes 5. More particularly, in these figures 2 and 3, the small contoured reinforcement passes through three consecutive nodes 5 housing it in the underlying bottom corrugation (not shown). For this purpose, the reinforcing portion 25 of the small-relief reinforcement is shown with a constant cross-section over the entire length of said small-relief reinforcement 12.

In particular, the ridges 31 of the reinforcing portion 25 are continuous over the entire length of said small-undulated reinforcing element 12, so as to reinforce the corresponding portions of the bottom corrugations 2, including the interruptions of said bottom corrugations 2 formed by the knots 5. Furthermore, the inner webs 17 of the small undulating stiffeners 12 are also continuous over the entire length of the small undulating stiffeners 12 to enhance the mechanical resistance to bending of all the small undulating stiffeners 12 in response to localized asymmetric pressures.

Furthermore, the sub-base 24 has a plurality of recesses 32 (see fig. 10), which in fig. 2 and 3 are three in number, i.e. one recess 32 at each node 5 traversed by a small undulating stiffener 12. These recesses 32 are produced in the lower wall 26 and in the side walls 27 of the base 24.

These notches 32 are arranged in the nodes 5 through which the small undulating stiffeners 12 pass. Furthermore, these notches 32 have a size larger than the size of the coupling member 21 received in the corresponding node. More particularly, these notches 32 have a depth greater than the thickness of the linking member 21 and a length taken along the longitudinal direction of the small contoured stiffener 12 greater than and preferably close to the width of the linking member 21 taken along the same direction. The notches 32 are penetrated by the coupling members 21 and allow the coupling members 21 to pass through in the nodes 5.

The small undulating stiffeners 12 thus ensure, on the one hand, continuity and alignment of the stiffeners on both sides of said node 5 by the continuous stiffening portions 25, allowing effective stiffening of the bottom corrugations 2, and, on the other hand, make it possible to keep aligned the large undulating stiffeners 11 on both sides of said node 5 by the notches 32 of the sub-base 24 crossed by the tie members 21.

The small contoured stiffener 12 preferably has a length corresponding to the length of the portion of the bottom corrugation 2 formed by the corrugated metal sheet 1. The portion of the bottom corrugation 2 of each corrugated metal sheet 1 can therefore be associated with a single small undulation reinforcement 12, facilitating the installation of the sealing membrane. For example, in the context of a corrugated metal sheet 1 as shown in fig. 1 and having the portion of the bottom corrugations 2 comprise-for each bottom corrugation 2-three consecutive nodes 5, the small corrugated reinforcing element 12 has three notches 32 so that said three consecutive nodes 5 can be crossed.

As shown in fig. 2 and 3, the end 33 of the small-undulated reinforcement 12 has a shell 34. These housings 34 are formed in the base 24.

Each housing 34 has a first opening 35 that opens outward at the end face of the small contoured stiffener 12. Further, each case 34 has a second opening 36 that opens outward at a lower surface 37 of the small contoured stiffener 12. In other words, these shells 34 are open on the lower surface 37 and the end faces of the small contoured stiffener 12.

As described above, the small-undulated reinforcing element 12 advantageously has a length corresponding to the length of the portion of the bottom corrugation 2 formed by the same corrugated metal sheet 1. In other words, the small contoured reinforcement 12 is interrupted by the opposite edges 45 of the corrugated metal sheet 1, said opposite edges 45 being parallel and interrupting the portion of the bottom corrugation 2 formed by said corrugated metal sheet 1. More particularly, said edge 45 interrupts the longitudinal portion 6 of the portion of the bottom corrugation formed by the corrugated metal sheet 1.

Thus, a row of small corrugated reinforcing elements 12 is housed under the bottom corrugations 2 formed by a plurality of corrugated metal sheets 1 welded together. The ends 33 of two successive small contoured stiffeners 12 are arranged in the same longitudinal portion 6 of the bottom corrugation 2. The first opening 35 of the housing 34 formed in said end 33 faces said longitudinal portion 2. A coupling bush 38 is fitted in the housing 34 formed at the facing ends 33 of the two continuous small contoured stiffeners 12.

Such a coupling bush 38 has a cross-section complementary to the cross-section of the hollow internal space of the sub-base 24 of the small contoured stiffener 12. Such a coupling bush 38 as shown in figure 3 therefore has a substantially rectangular cross-section and comprises a plurality of grooves 39 complementary to the ribs 29 forming the reinforcements of the subbase 24.

The coupling bush 38 is slidingly mounted in the shells 34 of the two successive small-relief stiffeners 12 and in the hollow internal space of the sub-base 24 to ensure the alignment of said two successive small-relief stiffeners 12 below the bottom corrugation 2.

The bottom corrugation 2 is thus reinforced in a continuous and aligned manner by the following two aspects: one of the two aspects is the continuity of the reinforcing portion 25 through the nodes 5 by the small-relief reinforcement 12 and the other of the two aspects is the assembly of two successive small-relief reinforcements 12 in aligned manner by means of the coupling bush 38 below said bottom corrugation 2.

Such undulating

stiffeners

11, 12 may therefore advantageously maintain a stable and reliable alignment of said undulating

stiffeners

11, 12, including in the presence of asymmetric stresses in the tank.

Such undulating

stiffeners

11, 12 may be produced in various materials, such as for example in materials such as metal, in particular aluminium, metal alloys, plastics, in particular polyethylene, polycarbonate, polyetherimide, or composites comprising fibres bonded by a plastic resin, in particular glass fibres.

The undulating

stiffeners

11, 12 may be produced in various ways. Preferably, these undulating

stiffeners

11, 12 are produced by extrusion.

Fig. 5 to 9 are schematic perspective views of the leakproof heat-insulating tank wall during installation, showing the step of installing the

corrugated reinforcements

11, 12 of the sealing film and the corrugated metal sheet 1 on the heat-insulating barrier 39.

During installation of the tank, rows of

corrugated stiffeners

11, 12 are mounted on the thermal insulation barrier 39 and held in place thereon before being covered by the corrugated metal sheet 1 shown in fig. 1.

Fig. 5 shows a portion of the sealing membrane during installation. In this fig. 5, some of the metal plates 1 of the sealing film have been anchored to the metal insert 40 of the thermal insulation barrier 39. Therefore, the portion of the large-undulated reinforcement 11 housed under the top corrugations 3 of the installed metal sheet 1 is not covered by the installed metal sheet 1. Furthermore, the coupling bush 38 fitted in the installed small undulating stiffener 12 is also not covered by the installed said metal plate 1.

In a first step, as shown in fig. 5, the large undulating fixing rail 41 and the small undulating fixing rail 42 are temporarily fixed on the thermal insulation barrier 39.

These fixing rails 41, 42 are fixed to the thermal insulation barrier 39 by any suitable means, for example by bolts, nails or the like. These fixing rails 41, 42 are temporarily fixed along a metal insert 40 designed to anchor the next metal sheet 1 to be mounted on the thermal insulation barrier 39. These fixing rails 41, 42 are temporarily fixed outside the area 43 of the thermal insulation barrier 39 designed to receive said next corrugated metal sheet 1 to be installed, to complete the sealing film.

In an embodiment not shown, the fixing tracks 41, 42 are temporarily anchored on pins for anchoring the thermal insulation barrier 39 or by fixing flanges sliding in the space between two insulating plates forming the thermal insulation barrier 39.

The fixing rails 41, 42 comprise through holes designed to receive the ends of the rows of undulating

stiffeners

11, 12 to hold said rows in position on the thermal insulation barrier 39, as described below. In this fig. 5, a large-undulated fixing rail 41 is provided to hold three rows of large-undulated reinforcements 11, and three small-undulated fixing rails 42 are provided, each to hold three small-undulated reinforcements 12.

Further, after the small undulating fixing rail 42 has been fixed on the thermal insulation barrier 39, a holding rod 44 is installed in the through hole of the small undulating fixing rail 42. These retaining bars 44 are arranged to protrude from the through holes of the small undulating fixing rail 42 only on the side of said small undulating fixing rail 42 for receiving the corrugated metal sheet 1 to be mounted on the thermal insulation barrier 39.

In a second step, as shown in fig. 6, rows of large undulating stiffeners 11 are placed on the thermal insulation barrier 39. These rows comprise a plurality of large undulating stiffeners 11 assembled together by linking members 21 to form a string of large undulating stiffeners 11.

The first ends of the rows of large undulating stiffeners 11 are assembled by the linking members 21 to the large undulating stiffeners 11 partially covered by the sheet metal that has been anchored to the thermal insulation barrier 39 in the vicinity of the region 43. This first end of the row of large undulating stiffeners 11 is thus held in place on the thermal insulation barrier 39 by engagement with said large undulating stiffeners 11 already held on the thermal insulation barrier 39 by said metal sheet 1 already mounted on the thermal insulation barrier 39.

The second ends of the rows of large undulating stiffeners 11 opposite the first ends are received in the through holes of the first fixing rail 41. The second ends of the rows of large undulating stiffeners 11 are thus held in place on the thermal insulation barrier 39 by said first fixing rail 41.

The coupling members 21 and the ends of the large undulating stiffeners 11 fixing the rows can thus hold the rows in place on the thermal insulation barrier 39.

In a third step, as shown in fig. 7, three small undulating stiffeners 12 are placed on the thermal insulation barrier 39. These small undulating stiffeners 12 are arranged so as to cover the junction members 21 of the large undulating stiffeners 11 of the rows at the nodes 5, the junction members 21 being housed in the recesses 32 formed in the sub-base 24 of the small undulating stiffeners 12.

Furthermore, the small contoured stiffener 12 is arranged so that the portion of the coupling bush 38 not covered by the installed corrugated metal sheet 1 is housed in the corresponding housing 34 of the end 33 of said small contoured stiffener 12. The insertion of said portion of the joint bushing 38 is facilitated by the second opening 36 of said housing 34, which allows to guide the small contoured stiffener 12 in terms of position on the thermal insulation barrier 39.

When these small undulating stiffeners 12 are correctly arranged on the thermal insulation barrier 39, the retaining bar 44 is slid into the through hole of the corresponding small undulating fixing rail 42 for insertion by sliding into the hollow portion of the small undulating stiffeners 12. These retaining bars 44 hold the small undulating stiffener 12 in place on the thermal insulation barrier 39.

As shown in fig. 8, this operation of positioning the small corrugated reinforcing member 12 and the slide retaining bar 44 is repeated for the remaining six small corrugated reinforcing members 12 to be installed before the corrugated metal sheet 1 is installed on the thermal insulation barrier 39.

In one embodiment, not shown, holding the small contoured stiffener 12 in place on the thermal insulation barrier 39 may be achieved or supplemented by other means, such as, for example, by means of double-sided tape, adhesives, or the like.

Finally, in a fourth step, shown in fig. 9, the corrugated metal sheet 1 is attached and anchored to the thermal insulation barrier 39 by welding on the metal inserts 40, thus covering the rows of large undulating stiffeners 11 and small undulating stiffeners 12, ensuring their fastening to the thermal insulation barrier 39. The fixing rails 41, 42 may then be removed and the installation of the corrugated reinforcing

members

11, 12 and the corrugated metal sheet may be continued by repeating the above steps.

Fig. 10 shows the installation of a small undulation reinforcement 12 before the last corrugated metal sheet 1 of the wall of the leakproof thermal insulation tank is anchored. As shown in fig. 10, mounting these small-undulated reinforcing members 12 is different from mounting other small-undulated reinforcing members 12 in that the small-undulated fixing rail 42 cannot be mounted on the thermal insulation barrier 39.

The small corrugated stiffener 12 is therefore installed to house the joining bushes 38, which are not covered by the corrugated metal sheet 1 already installed on the thermal insulation barrier 39, in the housings 34 at the two ends 33 of the small corrugated stiffener 12 still to be installed.

In a similar manner to the other small undulating stiffeners 12 already installed, the last small undulating stiffener 12 is positioned on the thermal insulation barrier 39 to accommodate the link members 21 of the large undulating stiffeners 11 of the rows already installed in the recesses 32 of the sub-base 24 of the small undulating stiffener 12.

Furthermore, the small corrugated stiffener 12 may be held in place on the thermal insulation barrier 39 by any suitable means, such as by double-sided tape or adhesive, before anchoring the last corrugated metal sheet 1.

The above-described technique for realising leak-proof thermally insulated tanks can be used in the case of accumulators of various types, for example to constitute the main sealing membrane of an LNG accumulator in a land unit or a floating structure such as a methane-carrying vessel or the like.

Referring to fig. 11, a cross-sectional view of a methane carrier 70 shows a leak-proof insulation tank 71 of generally prismatic form installed in the double hull 72 of the vessel. The walls of the tank 71 comprise a primary leak-proof barrier designed to be in contact with the LNG contained in the tank, a secondary leak-proof barrier arranged between the primary leak-proof barrier and the double hull 72 of the ship, and two insulating barriers arranged between the primary and secondary leak-proof barriers and between the secondary leak-proof barrier and the double hull 72, respectively.

In a manner known per se, a loading/unloading pipe 73 arranged on the upper deck of the vessel may be connected with suitable connectors to an offshore or port terminal for transferring the LNG cargo from the tank 71 or to the tank.

Figure 11 shows an offshore terminal comprising a loading dock 75, a subsea conduit 76 and a land means 77. Terminal 75 is a land fixture that includes a mobile arm 74 and a tower 78 that supports mobile arm 74. The moving arm 74 carries a bundle of insulated flexible hoses 79, which can be connected to the loading/unloading duct 73. The directionally movable arm 74 is adaptable to various sizes of methane transport vessels. A coupling conduit, not shown, extends within the turret table 78. The loading and unloading station 75 allows loading and unloading of the methane carrier from the land based plant 77 to the land based plant. The latter involves connecting a liquefied gas storage tank 80 and a coupling conduit 81 to the loading and unloading station 75 via a subsea conduit 76. The submerged conduit 76 allows for the transfer of liquefied gas over long distances, for example 5km, between the loading and unloading station 75 and the land based plant 77, which allows the methane transport vessel 70 to be kept at a large distance from shore during loading and unloading operations.

In order to generate the pressure required for transferring the liquefied gas, pumps onboard the vessel 70 and/or pumps provided in the land based plant 77 and/or pumps provided in the loading and unloading station 75 are used.

Although the invention has been described with reference to a number of particular embodiments, it is evident that it is not limitative and that it includes all the technical equivalents of the solutions described above and their combinations if these fall within the scope of the invention.

Use of the verb "to comprise" or "to include" and its conjugations does not exclude the presence of elements or steps other than those stated in the claims.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

1. A leak resistant tank wall comprising a corrugated sealing membrane, the sealing membrane comprising:

-a first series of corrugations, the corrugations (3) of the first series of corrugations being parallel,

-a second series of corrugations, the corrugations (2) of the second series of corrugations being parallel, an

-a planar portion (4), said planar portion (4) being located between a corrugation (3) of said first series of corrugations and a corrugation (2) of said second series of corrugations, and said planar portion (4) being designed to rest on a support surface,

the corrugations (3) of the first series of corrugations and the corrugations (2) of the second series of corrugations extending in intersecting directions, the corrugations (3) of the first series of corrugations and the corrugations (2) of the second series of corrugations comprising alternating longitudinal portions (6) and nodes (5), the nodes (5) being formed at the intersections of the corrugations (3) of the first series of corrugations and the corrugations (2) of the second series of corrugations,

the tank wall further comprises:

-a plurality of parallel rows of first undulating stiffeners, a row of first undulating stiffeners being arranged below a first corrugation belonging to said first series of corrugations, said row of first undulating stiffeners being arranged below successive longitudinal portions (6) of said first corrugation such that two successive first undulating stiffeners in said row are separated by a node (5) of said first corrugation, said two successive first undulating stiffeners being assembled in a position aligned below said first corrugation by a tie member (21), said tie member (21) passing through said node (5) separating said two successive first undulating stiffeners, said tie member (21) having a smaller dimension in the thickness direction of the tank wall than said first undulating stiffener,

-a second undulating stiffener arranged below a second corrugation belonging to said second series of corrugations, said second undulating stiffener passing through a plurality of consecutive nodes (5) of said second corrugation, said second undulating stiffener comprising a base (24) resting on said support surface and a stiffening portion extending over said base (24), said stiffening portion having a uniform cross-section over the length of said second undulating stiffener, a plurality of external notches (32) formed in said base (24) being arranged in respective nodes (5) of said second corrugation, said coupling members (21) passing through said nodes (5) being housed in corresponding said notches (32).

2. A leak-proof tank wall as claimed in claim 1, wherein said notch (32) is formed on the lower wall (26) of the second contoured stiffener so that the linking member (21) passes through the node (5) below the second contoured stiffener.

3. Leak-proof tank wall according to claim 1 or 2, wherein the sealing membrane comprises a corrugated metal sheet (1) delimited by edges,

and wherein the second undulating reinforcement extends from a first longitudinal portion (6) of the second corrugation interrupted by a first edge of the corrugated metal sheet (1) up to a second longitudinal portion (6) interrupted by a second edge of the corrugated metal sheet (1), the first edge of the corrugated metal sheet (1) being opposite to the second edge of the corrugated metal sheet (1), so that it passes through all the nodes (5) of the second corrugation formed by the corrugated metal sheet (1).

4. The tank wall of claim 1, comprising a row of the second undulating stiffeners disposed below the second corrugations.

5. Tank wall according to claim 4, wherein the sealing membrane comprises a plurality of corrugated metal sheets (1) welded together in a leak-tight manner,

and wherein a second undulating stiffener of said row of second undulating stiffeners extends from a first longitudinal portion (6) of said second corrugation, interrupted by a first edge of the respective corrugated metal sheet (1), up to a second longitudinal portion (6) interrupted by a second edge of said corrugated metal sheet (1), said first edge of said corrugated metal sheet (1) being opposite to said second edge of said corrugated metal sheet (1).

6. The tank wall of claim 4 or 5, wherein two consecutive second undulating stiffeners of said row of second undulating stiffeners are assembled by a coupling bushing (38) to keep said two consecutive second undulating stiffeners aligned below said second corrugations.

7. The tank wall according to claim 6, wherein an end (33) of a second undulating reinforcement of said row of second undulating reinforcements comprises a shell (34), said shell (34) having an opening (35) facing towards the facing second undulating reinforcement, said coupling bush (38) fitting in said shell (34) of two consecutive second undulating reinforcements of said row of second undulating reinforcements.

8. The tank wall according to claim 7, wherein the shell (34) of the second contoured stiffener is formed in the sub-base (24) of the second contoured stiffener, the sub-base (24) having a lower surface (37) resting on the support surface, the shell (34) being open on the lower surface (37) of the sub-base (24).

9. The tank wall according to claim 7, wherein said shell (34) comprises at least one reinforcement.

10. The tank wall of claim 1 wherein the first contoured stiffener comprises:

-a central portion (13) housed below the longitudinal portion (6) of a first corrugation of the first series of corrugations, the central portion (13) having a hollow base resting on the support surface,

-two hollow attachment spacers (14), said attachment spacers (14) being arranged on either side of the central portion (13), said attachment spacers (14) extending the hollow base of the central portion (13) and extending in nodes (5) located on either side of the longitudinal portion (6) of the central portion (13) of lower Fang Rongzhi,

the joining members (21) assembling two successive first yield reinforcements are housed in the hollow base of the central portion (13) of the first yield reinforcement and pass through the corresponding attachment spacers (14).

11. A vessel (70) for transporting cold liquid products, comprising a double hull (72) and a tank arranged therein, the tank comprising a leak-proof tank wall according to one of claims 1 to 10.

12. Method for loading or unloading a vessel (70) according to claim 11, wherein cold liquid product is transported from a floating or land storage (77) to the tanks (71) of the vessel or from the tanks of the vessel to the floating or land storage by insulated pipes (73, 79, 76, 81).

13. A transfer system for a cold liquid product, the system comprising: the vessel (70) of claim 11; insulated pipes (73, 79, 76, 81) arranged to connect tanks (71) installed in the hull of the vessel with a floating or land storage device (77); and a pump for flowing cold liquid product from the floating or land storage to the tank of the vessel or from the tank of the vessel to the floating or land storage through an insulated pipeline.