Flat thermal insulation panel for membrane tank wall

Abstract

The utility model relates to devices for storing and / or transporting low-temperature fluids, in particular to insulating panels used in the construction of the walls of sealed membrane-type thermal insulation tanks, located both on land and on floating structures. The technical problem solved by the utility model is to increase the operational reliability of membrane tanks for storing liquefied natural gas (LNG). The technical result consists in ensuring tightness, increasing the mechanical strength of the sealed membrane-type thermal insulation tank due to the uniform distribution of mechanical loads over the entire contact area of ​​the anchor plate with the mating parts, reducing local stresses in the anchor plate material and minimizing the likelihood of its deformation during operation. This technical problem is solved,and the technical result is achieved in a flat thermal insulation panel for the impermeable wall of a sealed membrane-type thermal insulation tank for a low-temperature fluid medium, comprising a sequentially installed lower plywood sheet, an auxiliary thermal insulation layer, a sealing auxiliary barrier, a main thermal insulation layer, an upper plywood sheet that completely covers the said main thermal insulation layer, and thermal protection elements placed on the surface of the upper plywood sheet with anchor metal plates designed with the possibility of attaching to them the corner sections of the corrugated membrane sheets of the impermeable wall of the sealed tank, wherein each anchor metal plate is provided with a centered fastening element,not protruding above the surface of the anchor plate and designed to allow the fixation of automatic welding equipment and the installation of auxiliary equipment when installing an insulation system in a tank for low-temperature liquid media.

Description

[0001] Application area

[0002] The utility model relates to devices for storing and / or transporting low-temperature fluid media, in particular to insulating panels used in the construction of the walls of sealed membrane-type thermal insulation tanks placed both on land and on floating structures.

[0003] Technology Level

[0004] The prior art discloses flat, two-layer insulating panels comprising an auxiliary heat-insulating barrier, an auxiliary sealing membrane, a primary heat-insulating barrier, a primary sealing membrane capable of contacting the product contained in the tank, as well as upper connecting panels and anchor elements for retaining the primary sealing membrane. The anchor elements are anchor plates capable of point-connecting the primary sealing membrane and the primary heat-insulating barrier through an intermediate layer of heat-protective material mounted on the primary heat-insulating barrier. The sheets of the primary sealing membrane are capable of universal orientation during installation due to identical, mutually perpendicular rows of wave-shaped corrugations formed on its outer surface (patent RU 2851408, publication date 11 / 24 / 2025).

[0005] A known guide system for a membrane welding device according to a utility model includes: an anchor tape located on an insulating wall forming an insulating system of a liquefied gas storage tank; a pin integrated with the anchor tape, the center of which deviates from the welding line of the anchor tape; and a guide rail connected to the pin to form a path of an automatic membrane welding device for welding membranes to be laid on the insulating wall. Thus, the present invention makes it possible to easily perform membrane welding and ensures stable guidance of the membrane welding device (patent US 20180299069, publication date October 18, 2018).

[0006] A structure for fastening an insulating wall of a liquefied natural gas storage tank is known. A connecting structure for an insulating panel of an independent liquefied natural gas storage tank is proposed, which makes it possible to reduce the time and effort required for installing an insulating panel attached to the outside of the main body of the tank. The connecting structure for the insulating panel of an independent liquefied natural gas storage tank includes a stud and an insulating panel. The stud is installed on the outside of the main body of the tank. The insulating panel is fixed to the outside of the main body by means of the stud. A body with a through hole is installed in the insulating panel having an insertion member. The insertion member is inserted into the through hole and has a hole into which the stud is inserted (patent. KR 20130091239, publication date 08 / 16 / 2013).

[0007] A flat insulating panel is also known, which sequentially comprises a bottom plywood plate, a first thermal insulation layer, an intermediate plywood plate with a thickness of at least 4±0.3 mm and completely covering the first thermal insulation layer, an impermeable overlay made of aluminum foil with a thickness of at least 70 μm, reinforced on both sides with fiberglass, a second thermal insulation layer covering the central zone of the impermeable overlay, and an upper plywood plate corresponding to the dimensions of the second thermal insulation layer and completely covering the second thermal insulation layer, wherein the above-mentioned elements are fastened together using polyurethane adhesive under the influence of force clamping loads. The utility model allows for improving the operational characteristics of the claimed insulating panel.

[0008] The closest analogue is a flat insulating panel, which sequentially contains a heat-insulating layer, a plywood plate completely covering said heat-insulating layer, and placed on the surface of said plate: a heat-protective strip extending in the longitudinal direction of said plywood plate and at the same distance from the edges of the insulating panel, and a heat-protective strip extending in the transverse direction of said plywood plate, in such a way that said heat-protective strips are arranged essentially crosswise, and at the junction of said heat-protective strips, the insulating panel contains a single anchor metal plate, essentially square in shape with rivets, made with the possibility of attaching to it exclusively the corner sections of the membrane sheets of the impermeable wall of the tank, the inner surface of which is in direct contact with the low-temperature fluid medium.The specified design of the flat insulating panel allows for a reduction in its weight, as well as a simplification of the method and reduction of the time for its assembly (patent RU 230171 U1, publication date 11 / 19 / 2024).

[0009] The disadvantage of the above technical solutions is the risk of displacement of the welding machine relative to the welding line, violation of the geometry of the weld seam and a decrease in the tightness of the joint, due to the lack of attachment points for the equipment of the automatic welding machine, ensuring its stable movement and correct positioning during the welding of the edges of the membrane sheets, on which there are no natural attachment points for the equipment of the automatic welding machine, for example, with corrugations that do not intersect

[0010] The technical problem solved by the utility model is to increase the operational reliability of membrane tanks for storing liquefied natural gas (LNG)

[0011] Disclosure of the essence of the utility model

[0012] The technical result consists in ensuring tightness, increasing the mechanical strength of a sealed membrane-type thermal insulation tank due to the uniform distribution of mechanical loads over the entire contact area of ​​the anchor plate with the mating parts, reducing local stresses in the material of the anchor plate and minimizing the likelihood of its deformation during operation.

[0013] The said technical problem is solved and the technical result is achieved by using a flat thermal insulation panel for the impermeable wall of a sealed membrane-type thermal insulation tank for a low-temperature fluid medium, comprising a sequentially installed lower plywood sheet, an auxiliary thermal insulation layer, a sealing auxiliary barrier, a main thermal insulation layer, an upper plywood sheet that completely covers the said main thermal insulation layer and thermal protection elements placed on the surface of the upper plywood sheet with anchor metal plates designed with the possibility of attaching to them the corner sections of the corrugated membrane sheets of the impermeable wall of the sealed tank, wherein each anchor metal plate is provided with a centered fastening element that does not protrude above the surface of the anchor plate,and designed with the ability to secure automatic welding equipment and install auxiliary equipment when installing an insulation system in a tank for low-temperature liquid media.

[0014] An additional feature is that the fastening element is completely recessed into the surface of the anchor plate.

[0015] An additional feature is that the fastening element is flush with the anchor plate.

[0016] An additional feature is that the fastening element is designed as a retainer containing a cylindrical body with an external thread in the upper part for mating with a removable mating part of the equipment, an elastic locking element for automatic fixation during installation, guide protrusions for positioning during installation and a sealing ring located in the annular groove of the body.

[0017] An additional feature is that the fastening element is made in the form of a locking mechanism, including a housing with an internal profile cavity, a rotary locking element with protrusions corresponding to the profile of the cavity, and a rotation locking mechanism.

[0018] Brief description of drawings

[0019] Fig. 1 - Double-layer insulation panel

[0020] In Fig. 2 - Anchor plate with a fastening element in the form of a lock for a quick-release mechanism

[0021] In Fig. 3 - Anchor plate with a fastening element in the form of a locking mechanism

[0022] Fig. 4 - Fastening the four edges of the sheets of the main sealing membrane to the anchor plate, which contains a countersunk fastening element in the central part

[0023] Fig. 5 - Anchor plate with indication of the directions of the welding lines of the edges of the sheets of the main sealing membrane

[0024] Explanation of symbols:

[0025] 1 - bottom plywood sheet

[0026] 2 - auxiliary thermal insulation layer

[0027] 3 - edges of membrane sheets

[0028] 4 - sealing auxiliary barrier,

[0029] 5 - main thermal insulation layer

[0030] 6 - top plywood sheet

[0031] 8 - Stainless steel anchor plates

[0032] 9 - fasteners

[0033] 10 - thermal protection element

[0034] 11 - rivets

[0035] 12 - Main sealing membrane

[0036] Implementation of a utility model

[0037] The design of a flat thermal insulation panel, having the shape of a rectangular parallelepiped (Fig. 1), contains the following interconnected elements:

[0038] The primary and secondary thermal insulation layers are made of foamed polymer blocks (polyurethane or polyisocyanurate). These blocks feature low thermal conductivity, minimizing gas loss during storage, and high structural strength, sufficient to withstand hydrostatic, hydrodynamic (sloshing), and thermal loads that occur during tank operation. The panel's load-bearing layers are comprised of outer and inner plywood sheets. The plywood sheets are bonded to the thermal insulation layers using an adhesive-based adhesive, ensuring high physical and mechanical properties over a wide temperature range.

[0039] Between the auxiliary thermal insulation layer 2 and the main thermal insulation layer 5, a multilayer sealing auxiliary barrier 4 is placed, made in the form of a composite of fiberglass, an adhesive layer and foil, and designed to protect the external supporting structures from the effects of the cryogenic liquid stored in the tank in an emergency situation when the main sealing membrane is damaged. Anchor plates 8 made of stainless steel are fixed in the upper plywood sheet 6, fixed by means of rivets 11 made of aluminum alloy; the said anchor plates 8 are intended for fastening the sheets of the main sealing membrane. Additionally, the structure is equipped with a thermal protection element 10, located in such a way as to protect the plywood layers from thermal damage during welding of the sheets of the main sealing membrane 12 directly at the installation site.

[0040] The top view demonstrates the presence of two rectangular contours in the panel structure (Fig. 1): an outer contour, including the main thermal insulation layer 5 and the upper plywood sheet 6, and an inner contour, formed by the auxiliary thermal insulation layer 2 and the lower plywood sheet 1. The contours are located coaxially, their sides are mutually parallel, while the linear dimensions of the inner rectangle (length and width) are smaller than the corresponding dimensions of the outer rectangle, which forms a stepped structure of the panel cross-section. All structural elements are rigidly connected to each other, forming a single structural unit with specified thermal insulation, strength and protective characteristics, ensuring reliable operation of the panel as part of an insulation system for cryogenic liquid storage tanks.

[0041] Membrane cargo containment systems typically utilize two design solutions for insulating flat panels. Double-layer flat panels with a secondary barrier are used in areas requiring additional protection from potential contact with the cryogenic liquid, such as areas with a high risk of localized damage to the primary containment layer. Single-layer flat panels without a secondary barrier are used in areas where direct contact with the cryogenic product is completely excluded throughout the tank's service life. These panels are typically installed at the top of the tank or in areas with minimal risk of emergency leaks, optimizing the weight and cost of the insulation system without compromising the overall reliability of the structure.

[0042] Fastener 9, located on anchor plate 8, which is embedded in the top plywood sheet 6 of the membrane tank insulation system's thermal insulation panel, provides reliable and versatile mounting for automatic welding equipment and auxiliary equipment during installation of the LNG tank insulation system. Specifically, it addresses the issue of ensuring stable positioning of the welding machine along the welding line, taking into account the tank's complex spatial configuration (horizontal, vertical, and overhead sections) and the membrane's structural features.

[0043] This solution is particularly necessary when using 12 stainless steel sheets with non-intersecting corrugations as the primary sealing membrane (Fig. 4): this design lacks natural mounting points for the automatic welding machine, which would ensure its stable movement and correct positioning during the welding process of the membrane sheet edges. The lack of fixing points leads to the risk of the welding machine shifting relative to the welding line, disrupting the weld geometry, and reducing the seal integrity of the joint, which is unacceptable for LNG tank operation.

[0044] The use of fastener 9 on anchor plate 8 creates reliable support points for attaching the welding equipment guides and clamps directly to the thermal insulation panel, ensuring stable positioning of the welding machine in all areas of the tank's complex spatial configuration (horizontal, vertical, and overhead), precise tracking along the welding line without deviation, uniform distribution of equipment loads on the panel's supporting elements, and maintaining the membrane's structural integrity during welding operations. At the same time, securing the equipment via fasteners 9, centered on anchor plates 8, ensures secure attachment of the auxiliary rail to the thermal insulation panel and maintains its specified spatial position during welding, includingunder the influence of dynamic and temperature loads, and also provides the ability to precisely position the welding head to form a continuous weld seam between membrane sheets.

[0045] Furthermore, fastener 9 is multifunctional and can be used not only for securing automatic welding equipment but also for mounting auxiliary equipment during the installation of the insulation system in an LNG tank—for example, for securing lifting mechanisms, positioning devices, or quality control tools. This makes it possible to quickly secure lifting equipment when moving and installing heavy insulation system components, secure measuring and control devices at specified points to monitor installation quality (checking flatness, gaps, and joint tightness), and install auxiliary guides and support structures necessary at various stages of insulation system assembly.

[0046] Thus, the utility model comprehensively eliminates the problem of unstable equipment positioning: high installation accuracy is achieved in areas of any spatial orientation, eliminating the risk of displacement relative to the welding line and joint leakage, which is critical for the reliable operation of the LNG tank. The multifunctionality of fastening element 9 improves installation efficiency, reduces insulation system assembly time, and minimizes the need for additional fastening solutions, providing a single, unified system for securing various equipment to the surface of thermal insulation panels.

[0047] The number of anchor plates (8) with fasteners (9) located on the thermal insulation panel is determined based on the technical requirements for the installation of an auxiliary rail, which ensures the movement of the welding head of the automatic welding machine along the specified trajectory of joining the membrane sheets. The spatial arrangement of the anchor plates (8) with fasteners (9) on the thermal insulation panel is determined based on the configuration of the trajectory of joining the membrane sheets 12, the requirements for the continuity of the formed weld seam, and the conditions for ensuring stable and accurate movement of the welding head.

[0048] During the welding operation (Fig. 4), the four edges of different membrane sheets are connected around the fastening element 9, which is pre-installed in the center. In this case, the fastening element 9, located in the central part of the anchor plate 8, does not interfere with the formation of the required connection configuration - the edges of the membrane sheets 3 are welded around it, leaving the element 9 inside the connection structure (Fig. 5).The central portion of anchor plate 8 is a technologically convenient area specifically used to accommodate the fastening device, which provides a number of significant advantages: it eliminates the fastening element's interference with the weld formation zone and minimizes the risk of connection defects; guarantees unimpeded access of the welding machine to the weld lines along the edges of the membrane sheets; simplifies the installation and maintenance of fastening elements due to free access to the central portion of the anchor plate; and avoids the thermal impact of the welding process on the fastening device materials, thereby increasing its durability and operational stability.

[0049] At the same time, the fastening device 9 is designed to ensure high reliability of fixation and at the same time is optimized for ease of installation, which allows for a reduction in labor costs during installation and ensures the stability of the position of the equipment during welding operations.

[0050] The use of automatic welding equipment for welding membrane sheets of the primary sealing barrier in membrane tank insulation systems (including those designed for storing liquefied natural gas (LNG)) enables the critically important complete sealing of the structure. Consistently high-quality welded joints are achieved through precise maintenance of specified process parameters (current, voltage, and welding speed), eliminating the influence of subjective factors typical of manual welding.

[0051] The invention proposes using a concealed fastening element 9, positioned in the central portion of an anchor plate 8, which is part of a flat insulating panel. The fastening element's design and installation method provide for the fastening elements to be completely recessed into the surface of the anchor plate or flush with it (see Figs. 2, 3), ensuring a flat, level working surface for the anchor plate without protruding elements.

[0052] This design solution eliminates the disadvantages typical of solutions with traditional fasteners, namely: it eliminates the risk of injury to personnel (cuts, abrasions) when moving and installing insulating panels, since there are no protruding fasteners; it allows for compact storage and transportation of panels in stacks without mutual damage to surfaces and deformation of fasteners, as well as without increasing the dimensions of the packaging and the occurrence of stress concentration points during stacking; it guarantees unhindered installation of thermal insulation panels by eliminating the risk of snagging and damage to the panels themselves and their insulating layer during positioning and fixation in the tank;does not interfere with the welding of membrane sheet edges - the welding equipment moves freely along the working surface of the plate, eliminating the need to adjust the tool's trajectory or perform additional preparatory operations to remove burrs or deformed fasteners.

[0053] Furthermore, the recessed or flush placement of fastener 9 facilitates the uniform distribution of mechanical loads across the entire contact area of ​​anchor plate 8 with the mating components, which increases the overall reliability of the connection, reduces local stresses in the plate material, and minimizes the likelihood of its deformation during operation. This circumstance is particularly important given the functional purpose of the anchor plate: to serve as a support element for securing the corners of corrugated metal sheets 12, which form the main sealing membrane of the tank.

[0054] The concealed fastening element 9, located on the anchor plate 8 of the thermal insulation panel, can be made in two versions: in the form of a clamp for a quick-release connection (see Fig. 2) or in the form of a locking mechanism (see Fig. 3). In this case, the fastening element 9 is centered on the anchor plate 8, which ensures its precise positioning relative to the geometric center of the plate 8. The design of the fastening element provides for its recessed execution or placement flush with the surface of the anchor plate, due to which a flat working plane of the thermal insulation panel is maintained without protruding elements.

[0055] The quick-release coupling retainer (Fig. 2) comprises a cylindrical body with an external thread in the upper part for mating with a removable mating part of the equipment, an elastic locking element in the form of a spring ring or a petal mechanism for automatic fixation during installation, guide projections for correct positioning during installation and a sealing ring made of cryogenic-resistant elastomer (based on fluororubber or silicone), located in an annular groove of the body. The connection is made by inserting the mating part of the equipment into the body until the locking element is triggered; disconnection is performed by pressing the unlocking mechanism or by applying axial force, overcoming the resistance of the spring. The quick-release coupling allows for the installation / dismantling of equipment in less than 5 s.

[0056] The locking mechanism (Fig. 3) is a more reliable design solution and includes a housing with an internal profile cavity, a rotating locking element with projections matching the cavity profile, and a rotation locking mechanism (ball or cam lock). Installation is accomplished by inserting the mating part of the hardware into the housing's profile cavity and then rotating it to a predetermined angle (30-90°), at which point the locking element's projections engage the stops, and the locking mechanism prevents reverse rotation. This design prevents spontaneous disengagement under vibration or dynamic loads.

[0057] The tightness of both fastening element 9 designs is a critical requirement, as the components come into contact with or are in close proximity to the stored cryogenic liquid. Tightness is ensured through a combination of design and manufacturing solutions and through leak testing of the connections during manufacturing (e.g., testing with a helium leak detector).

[0058] Implementation of the specified design solutions eliminates the penetration of cryogenic liquid into the fastening area, the formation of ice plugs or frost in gaps, corrosion of metal components and damage to thermal insulation due to local cold leaks.

[0059] The proposed design of fastening element 9 ensures: fast and reliable fastening of various types of equipment (welding equipment, lifting mechanisms, positioning devices, installation quality control tools); maintaining the flatness of the working surface of the thermal insulation panel; complete tightness of connections under cryogenic temperatures; uniform distribution of mechanical loads when fixing equipment; reduction of local stresses in the anchor plate material; durability and trouble-free operation in the aggressive operating environment of the LNG tank.

[0060] Thus, the use of a concealed fastening element in the central part of the anchor plate, which is part of the insulation panel, provides a comprehensive solution to technical problems: it guarantees the safety of personnel during installation, simplifies the logistics and storage of panels, ensures unhindered installation and welding operations, and also increases the reliability and durability of the structure as a whole.

[0061] Thus, by incorporating a fastener into the anchor plate, it became possible to use automatic welding equipment. This allows for the automated welding process, which in turn increases the speed and quality of installation of the primary sealing membrane. This increases the reliability of the tank and reduces installation time. Furthermore, the fastener is used not only to secure the automatic welding equipment (including the auxiliary rail for moving the welding head), but also for mounting auxiliary equipment: lifting mechanisms, positioning devices, installation quality control devices. Furthermore, the fastener can be reused during the phased installation and maintenance of the tank.

Claims

1. A flat thermal insulation panel for an impermeable wall of a sealed membrane-type thermal insulation tank for a low-temperature fluid medium, comprising a sequentially installed lower plywood sheet, an auxiliary thermal insulation layer, a sealing auxiliary barrier, a main thermal insulation layer, an upper plywood sheet completely covering the said main thermal insulation layer, and thermal protection elements placed on the surface of the upper plywood sheet, with anchor metal plates designed with the possibility of attaching to them corner sections of corrugated membrane sheets of the impermeable wall of the sealed tank, characterized in that the anchor metal plate is provided with a centered fastening element,not protruding above the surface of the anchor plate and designed to allow the fixation of automatic welding equipment and the installation of auxiliary equipment when installing an insulation system in a tank for low-temperature liquid media.

2. A flat thermal insulation panel for an impermeable wall of a sealed thermal insulation tank of a membrane type for a low-temperature fluid medium according to paragraph 1, characterized in that the fastening element is completely recessed into the surface of the anchor plate.

3. A flat thermal insulation panel for an impermeable wall of a sealed thermal insulation tank of a membrane type for a low-temperature fluid medium according to paragraph 1, characterized in that the fastening element is located flush with the anchor plate.

4. A flat thermal insulation panel for an impermeable wall of a sealed thermal insulation tank of a membrane type for a low-temperature fluid medium according to paragraph 1, characterized in that the fastening element is made in the form of a retainer containing a cylindrical body with an external thread in the upper part for mating with a removable mating part of the equipment, an elastic locking element for automatic fixation during installation, guide protrusions for positioning during installation and a sealing ring located in an annular groove of the body.

5. A flat thermal insulation panel for an impermeable wall of a sealed thermal insulation membrane tank for a low-temperature fluid medium according to paragraph 1, characterized in that the fastening element is made in the form of a locking mechanism including a housing with an internal profile cavity, a rotary locking element with projections corresponding to the profile of the cavity, and a rotation locking mechanism.

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