Method of insulating storage tanks for fluid and storage tanks for fluid

Abstract

The present invention relates to storage tanks for holding a fluid and to a method of insulating such tanks. An insulating cladding system is provided in which open-sided profiles are arranged on a shell and / or roof of a storage tank to support one or more layers of insulation material and a polymeric membrane positioned above the insulation material.

Description

[0001] Method of insulating storage tanks for fluid and storage tanks for fluid Technical field of the invention

[0002] The present invention relates to storage tanks for fluid, in particular oil storage tanks.

[0003] Background of the invention

[0004] Large oil storage tanks are structures designed to safely store vast quantities of liquid hydrocarbons while addressing challenges, such as thermal efficiency, safety, and environmental protection. Among the different designs, fixed roof tanks are widely used, especially for storing lower-volatility oils. These tanks feature a permanent roof structure, typically dome-shaped or conical, which is welded or bolted to the cylindrical shell. The fixed roof design provides a robust and simple solution, offering durability and protection against environmental factors such as rain and debris.

[0005] The structural components of a fixed roof tank include the shell, roof, bottom plate, and foundation. The shell, constructed from carbon steel or stainless steel, provides the primary containment and is designed to handle the hydrostatic pressure from the stored oil. It is supported by a solid foundation, often made of reinforced concrete, which ensures stability and prevents settlement. The roof itself is a key feature, serving to shield the stored oil from weather and external contamination while maintaining the structural integrity of the tank.

[0006] One critical aspect of fixed roof tanks is ventilation. Proper venting systems, including normal vents and emergency pressure relief valves, are installed to manage the release of gases generated by the stored oil. This prevents dangerous pressure buildup inside the tank, which could compromise its structural integrity. In some cases, these tanks are also equipped with vapor recovery systems to capture hydrocarbon vapours and mitigate environmental impact.

[0007] A particularly important feature of fixed roof tanks is their insulation. Insulating the tank, including the roof, is essential for maintaining the oil at a consistenttemperature. The roof is especially susceptible to heat exchange with the environment, as it is directly exposed to sunlight, precipitation, and ambient temperature variations. Without proper insulation, the temperature of the oil could fluctuate significantly, leading to increased evaporation, changes in viscosity, and the potential for condensation within the tank. Insulating the roof helps reduce these temperature fluctuations, ensuring the stored oil remains stable and within the desired thermal range.

[0008] Insulation materials, such as polyurethane foam, mineral wool, stone wool, or fiberglass, are commonly used, often encased in protective cladding to shield them from weathering. This not only enhances thermal efficiency but also contributes to the longevity of the tank by minimizing thermal stresses on the structure.

[0009] The issue of cladding on insulated oil storage tanks becoming leaky due to temperature variations is a significant concern for maintaining their structural integrity and operational efficiency. The cladding, often made of aluminium or stainless steel, serves as a protective barrier, shielding the insulation from environmental elements such as rain and snow. However, temperature fluctuations can cause the cladding to expand and contract, leading to the formation of gaps, cracks, or loosening of seams overtime. When this occurs, the cladding can no longer effectively protect the insulation, allowing rainwater and moisture to infiltrate.

[0010] Once the insulation becomes wet, its thermal efficiency is compromised. This leads to increased exposure of the tank’s shell and roof to temperature variations, which, in turn, exacerbates several critical issues. One of the primary concerns is the impact of thermal stress. The steel plates that make up the tank shell and roofing experience greater expansion and contraction due to fluctuating temperatures. This movement imposes strain on the weld seams and connections between the plates, increasing the risk of microfractures or larger leaks, ultimately jeopardizing the tank’s ability to safely contain its contents.

[0011] Additionally, wet insulation creates a damp environment that accelerates corrosion on the tank’s surface. Trapped moisture, often combined with corrosive agents, such as salts or pollutants, attacks the steel plates, reducing their thickness and structuralstrength overtime. This corrosion is particularly problematic where protective coatings may have been damaged, further increasing the risk of leaks.

[0012] The loss of effective insulation also has operational implications. Without proper insulation, the tank becomes more susceptible to heat loss or gain, depending on the ambient conditions. This necessitates increased energy use to maintain the stored oil at its optimal temperature, driving up operational costs. Furthermore, the moisture retained in the insulation adds extra weight to the structure, particularly on the roof. This additional weight increases stress on the roof plates and connections, potentially leading to structural deformation or failure.

[0013] The combined effects of these issues also pose significant environmental and safety risks. Structural weaknesses can result in hydrocarbon leaks, leading to soil and groundwater contamination. Additionally, escaping volatile vapours increase the risk of fire or explosion, creating safety hazards for personnel and surrounding areas.

[0014] US3010599 (A) discloses a thermally insulated tank comprising a plurality of spaced nonconducting supports of l-shape in cross section, connecting bands received through openings in said supports closely adjacent to the base flanges thereof, encircling said tank and securing said supports to the surface of the tank, and rectangular-preformed panels of semirigid, resilient thermal insulation material of substantially uniform thickness throughout positioned on edge in radially sprung condition between each adjacent pair of said supports and confined against radial displacement by the flanges of said supports.

[0015] Summary of the invention

[0016] It is an object of the present invention to mitigate the above-mentioned risks, by providing an insulating cladding system that is more resistant to temperature variations.

[0017] A first aspect relates storage tank for holding a fluid, the tank comprising:

[0018] - a shell;

[0019] - a roof fixed to the shell; and- an insulating cladding system;

[0020] wherein the insulating cladding system comprises:

[0021] - a plurality of open-sided profiles, preferably customizable, fastened to the shell and / or roof; wherein the open-sided profiles each comprises a top face, a bottom face, a first side face connecting the top and bottom faces, and an open side face positioned opposite to the first side face;

[0022] - one or more layers of insulation material mounted between, above, and preferably within, the open-sided profiles; and

[0023] - a membrane of a polymeric material, preferably unvulcanised, placed above the insulation material.

[0024] A second aspect relates to a method of insulating a storage tank for holding a fluid, the method comprising:

[0025] - providing a storage tank comprising a shell and a roof fixed to the shell;

[0026] - fastening a plurality of open-sided profiles, preferably customizable, to the shell and / or roof; wherein the open-sided profiles each comprises a top face, a bottom face, a first side face connecting the top and bottom faces, and an open side face positioned opposite to the first side face;

[0027] - mounting one or more layers of insulation material between, above, and preferably within, the open-sided profiles; and

[0028] - mounting a membrane of a polymeric material, preferably unvulcanised, above the insulation material.

[0029] As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and / or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about", it will be understood that the particular value forms another embodiment.

[0030] It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.Detailed description of the invention

[0031] General interpretation notes

[0032] In the present context, the term “in general” when used when mentioning a feature relating to the present invention, it must be understood that the feature may be used with all embodiments of the invention, even if the mentioning is made in the detailed part of the document.

[0033] Storage tank structure

[0034] In general, the structural components of a fixed roof tank include a shell, roof, and a bottom plate. The shell, often constructed from carbon steel or stainless steel, provides the primary containment and is designed to handle the hydrostatic pressure from stored oil or liquefied gas. It may be supported by a solid foundation, often made of reinforced concrete, which ensures stability and prevents settlement. The roof itself is a key feature, serving to shield the stored oil or liquefied gas from weather and external contamination while maintaining the structural integrity of the tank.

[0035] Insulating cladding system overview

[0036] The insulating cladding system according to the present invention is based on a support structure of a plurality of open-sided profiles that are fastened to the shell and / or roof of the storage tank. The open-sided profiles each comprises a top face, a bottom face, a first side face connecting the top and bottom faces, and an open side face positioned opposite to the first side face. The elements are profiles, e.g., extruded profiles, with an open side, typically having a U-, C-, sigma-, Z-, or other similar shape, allowing for absorption of movement from the underlying structure. These profiles are preferably adapted to be adhered to the storage tank surface (especially the roof and shell surfaces) that is prone to expansion and contraction due to thermal changes, mechanical forces, or other dynamic factors. The use of an adhesive to mount the profiles eliminates the need to penetrate the underlying structure, preserving its integrity while ensuring a secure attachment.Movement absorption by the open-sided profiles

[0037] The open-sided design of the profiles is integral to their functionality, allowing them to absorb movement from the underlying tank surface. The flexibility provided by this open configuration enables the profiles to adapt to dimensional changes in the substrate without compromising their structural integrity. Movements, such as expansion or contraction, primarily affect the lower face of the profile, which remains in contact with the tank surface. The lower face of the profile can flex, slide, or deform slightly in response to these forces, depending on the specific material properties and geometric design of the profile.

[0038] In contrast, the upper face of the profile, which primarily serves as a support for the insulation and the membrane, remains largely unaffected by the movements of the tank surface. This separation of dynamic forces ensures that any structure mounted on the upper face retains its stability and is not subjected to the stresses or distortions caused by the movement of the underlying tank surface.

[0039] The open-sided profile shape provides inherent structural stiffness, allowing the profiles to maintain their shape while absorbing and compensating for movements. Features, such as flanges, grooves, or ribs may be integrated into the design to enhance their ability to flex or accommodate sliding motion.

[0040] In one or more embodiments, the open side face is oriented laterally relative to the shell and / or roof.

[0041] In one or more embodiments, the bottom face faces the shell and / or roof and the top face faces away from the shell and / or roof.

[0042] Sliding motion accommodation

[0043] The open-sided profiles may be designed not only to flex but also to accommodate sliding motion, which occurs when the surface they are adhered to expands or contracts in response to temperature changes or external forces. This sliding motion is absorbed through a combination of material properties, geometric design, and the way the profiles interact with both the substrate and the mounted structures.The profiles are typically made of materials such as plastic, aluminium, or steel, each of which has properties suited to managing sliding forces. For example, plastic profiles may exhibit inherent elasticity, allowing for minor deformations that dissipate the forces generated by sliding motion. Aluminium and steel, while stiffer, can be designed with specific geometries (e.g., flanges or ribs) to allow controlled bending or sliding movement without compromising the integrity of the profile.

[0044] The open-sided nature of the profiles provides a space or “gap” that enables controlled movement. When the substrate expands or contracts, the open side allows the profile to adjust by flexing or slightly shifting its lower face, which remains adhered to the surface. This movement prevents excessive stress from transferring to the mounted structure on the upper face, ensuring stability.

[0045] The profiles are preferably adhered to the tank surface using adhesives that permit minor shifts without delaminating. High-performance adhesives with some level of flexibility allow the lower face of the profile to slide marginally over the substrate in response to movement, rather than resisting it entirely. This flexibility in the adhesive layer acts as a buffer, reducing stress concentrations and allowing the profile to absorb sliding motion effectively.

[0046] Specific geometric elements can be incorporated into the profile design to enhance its ability to accommodate sliding motion. For example, grooves or channels that when formed in the lower face can create controlled points of movement, enabling the profile to adjust incrementally in response to sliding forces.

[0047] Flanges at the open side of the profile may act like springs, flexing to absorb some of the motion without causing permanent deformation. Ribs or reinforcements allow the profile to maintain structural integrity while enabling controlled deformation or sliding.

[0048] Hence, by concentrating the sliding motion within the lower face and adhesive layer, the profile effectively isolates these forces from the upper face. This ensures that the structures mounted on the upper face remain unaffected by the movement of the tank structure. The open-sided profile acts as a buffer zone, allowing for dynamic adjustments without transmitting stresses to the supported elements.The choice of material, whether plastic, aluminium, or steel, also influences the degree of flexibility and durability of the profiles, ensuring they can meet the specific demands of their intended application.

[0049] By adhering the profiles to the surface instead of mechanically fastening them, the system avoids the need for perforating the tank, which is particularly important for maintaining the tank’s structural integrity.

[0050] Profile arrangement and spacing

[0051] The arrangement of the open-sided profiles may be carefully designed to achieve optimal structural support while accommodating the dynamic movements of the underlying surface. The profiles are preferably positioned with a distance between the side faces of neighbouring profiles within the range of 10 to 150 cm, with a preferred range of 25 to 100 cm. This spacing ensures adequate coverage and support while allowing flexibility for expansion and contraction of the substrate.

[0052] A first group of open-sided profiles may be arranged in parallel alignment with one another, creating a uniform and organized configuration. This parallel arrangement facilitates efficient load distribution and provides a stable base for mounting additional structures of the insulating cladding system. To further enhance the structural integrity and accommodate multidirectional forces, a second group of open-sided profiles may be arranged in parallel alignment with one another and positioned within the interspaces between the profiles of the first group. The second group of profiles is oriented in a non-parallel manner relative to the first group, preferably perpendicularly, to form an intersecting pattern. This intersecting arrangement, which can take the form of a grid-like pattern, enhances the overall stability of the system and ensures consistent support across the entire surface.

[0053] The combination of parallel and intersecting arrangements provides a robust framework that effectively absorbs movements from the underlying structure while maintaining the integrity of any components mounted on the upper face of the profiles. The strategic placement of the profiles within the defined spacing range further contributes to their ability to flex and adapt to environmental changes without compromising performance.In one or more embodiments, the distance between side faces of neighbouring open-sided profiles is within the range of 10-150 cm, such as 15-140 cm, e.g., 20-130 cm, preferably within the range of 25-100 cm.

[0054] In one or more embodiments, a first group of the open-sided profiles are arranged in parallel alignment with one another.

[0055] In one or more embodiments, a second group of open-sided profiles are arranged in parallel alignment with one another and positioned within the interspaces between the profiles of the first group, and wherein the second group of profiles is oriented non-parallel, preferably perpendicularly, relative to the first group of profiles, thereby forming an intersecting pattern, e.g., a grid-like pattern.

[0056] Insulation material (rigid batts)

[0057] In the present context, rigid batts are generally preferred over soft batts, primarily because of their structural stability and suitability for industrial applications. The storage tanks for fluid require insulation that can endure internal forces, external forces, environmental conditions, and the challenges posed by their size and shape. Rigid batts maintain their shape and structural integrity overtime, even when exposed to compression, vibrations, or external pressure. This makes them ideal for applications where insulation needs to remain stable against large, flat, or curved surfaces like oil tanks. In contrast, soft batts, often made from loose fiberglass or mineral wool, are more prone to sagging, settling, or displacement, which can lead to thermal gaps and reduced insulation performance overtime.

[0058] Furthermore, rigid batts are easier to affix securely to the surface of the tank using adhesives, mechanical fasteners, or integrated panel systems. They also often include vapor barriers or moisture-resistant facings, making them better suited for outdoor applications where exposure to weather and humidity could degrade softer materials. Such rigid batt insulation materials are typically manufactured from high-performance compositions that enhance both thermal and mechanical properties. Common materials include fiberglass, which is valued for its high thermal resistance and non-combustibility. Mineral wool is also known for its superior fire resistance,and rigid foam boards made from polystyrene, polyisocyanurate, or polyurethane offer excellent thermal insulation with the added benefit of moisture resistance.

[0059] In one or more embodiments, the one or more layers of insulation material is in the form of rigid batt insulation, such as mineral-based rigid batt insulation or foam-core rigid batt insulation.

[0060] Membrane (waterproofing layer)

[0061] The membrane for the insulating cladding system according to the present invention is present to provide waterproofing. The membrane provides a continuous, robust barrier that prevents water infiltration and ensures the structural integrity and operational safety of the tank. Membranes can adapt to the surface contours of the tank’s roof and / or walls, providing seamless coverage that minimizes the risk of leaks or breaches overtime.

[0062] The ideal materials for such a membrane are sheet materials made from polymeric substances, which combine flexibility, durability, and excellent water resistance. Preferred polymers for this application include polyisobutylene (PIB), butyl rubber, and brominated isobutylene-co-paramethylstyrene (BIMS). These materials are known for their low permeability to water and their resistance to chemical degradation, making them suitable for prolonged exposure in harsh environments typical of oil tank installations. In some cases, mixtures of these polymers can be used to optimize performance characteristics, such as enhancing flexibility while maintaining impermeability.

[0063] The sheet material for the membrane preferably has a thickness comparable to standard water membranes, with a preferred range of 2 to 4 millimetres. This thickness provides sufficient mechanical strength and resistance to punctures or tears while maintaining the flexibility required for installation and long-term performance.

[0064] A preferred material for the membrane is one or more non-vulcanised elastomeric polymers, preferably selected from: Brominated Isobutylene paraMethyl-Styrene (BIMS), Isobutylene-lsoprene Rubber (HR), Chlorinated Isobutylene-lsopreneRubber (CIIR), Brominated Isobutylene-lsoprene Rubber (BUR), Pre-crosslinked Isobutylene-lsoprene Rubber (XI I R) , Co-polymers of Ethylene Propylene Rubber (EPM), Ter-polymers of Ethylene Propylene Diene Monomer Rubber (EPDM), mixtures thereof, and reclaimed rubber based on the rubbers or mixtures of rubbers described above.

[0065] A preferred material for the membrane is PIB, BIMS, HR, CIIR, BUR, XIIR, EPDM, EPM, and mixtures thereof.

[0066] A more preferred material for the membrane is PIB or BIMS mixed with HR (preferably including reclaimed butyl), BUR, XIIR, CIIR, EPDM (preferably including reclaimed EPDM), and / or EPM (preferably including reclaimed EPM).

[0067] The blend of PIB and HR, both being derivatives of isobutylene, creates a material that is highly impermeable to gases and liquids while maintaining excellent flexibility and tackiness. PIB contributes to the material’s self-sealing properties, making it ideal for membranes that need to remain watertight even when punctured. HR enhances this blend by adding resilience and durability, ensuring that the material can withstand mechanical stress and environmental exposure without losing its sealing capabilities.

[0068] Combining BIMS with HR results in a material that balances chemical and thermal resistance with excellent sealing properties. BIMS, being a brominated version of butyl rubber, introduces enhanced adhesion and stability at higher temperatures, making it particularly suitable for environments where the material may be exposed to heat or chemicals. When blended with HR, the resulting material retains flexibility and impermeability, making it well-suited for membrane applications where both durability and resistance to harsh conditions are required.

[0069] A blend of PIB and BIMS leverages the strengths of both materials to create a highly tacky and durable adhesive compound. PIB’s natural stickiness and elasticity make it an excellent base for self-sealing applications, while BIMS enhances the overall durability and chemical resistance. This combination is particularly effective in membranes that need to maintain their integrity over time, even under challengingenvironmental conditions, by providing both immediate adhesion and long-term stability.

[0070] The combination of PIB with EPDM results in a material that is not only flexible and impermeable but also highly resistant to weathering. EPDM is renowned for its ability to withstand UV radiation, ozone, and extreme temperatures, making it an ideal partner to PIB in creating a roofing membrane or protective barrier that can endure prolonged exposure to outdoor elements. The blend ensures that the material remains effective overtime, providing reliable sealing and protection against environmental factors.

[0071] Similarly, blending PIB with EPM, which is chemically similar to EPDM but without the diene component, produces a material that offers good weather resistance and flexibility. EPM adds stability and elasticity, which, combined with PIB’s tackiness and impermeability, creates a versatile material suitable for membranes. This blend is particularly advantageous in situations where long-term exposure to varying weather conditions is expected, as it maintains its sealing properties while resisting environmental degradation.

[0072] When BIMS is combined with EPDM, the result is a material that excels in chemical and thermal resistance while also being highly durable in outdoor conditions. BIMS contributes to the material's adhesive strength and resistance to chemicals, making it particularly useful in applications where exposure to harsh substances is a concern. EPDM, with its excellent resistance to UV radiation and ozone, ensures that the material remains functional and resilient in outdoor environments, making this blend ideal for protective membranes that must perform reliably in harsh conditions.

[0073] A blend of BIMS with EPM offers a similar balance of properties, with the added benefit of EPM’s stability and elasticity. This combination results in a material that is both chemically resistant and flexible, capable of maintaining its integrity under mechanical stress and environmental exposure. The blend is particularly well-suited for applications in membranes, where the ability to resist chemicals and withstand outdoor conditions without losing flexibility is critical.The molecular weight of each polymer in these blends is critical in achieving the right balance of tackiness, adhesion, and mechanical properties. For blends like PIB with HR or BIMS, lower molecular weights of PIB can enhance tackiness, while medium to higher molecular weights of HR or BIMS provide elasticity and durability. In combinations involving EPDM or EPM, the molecular weight is crucial for maintaining flexibility and weather resistance, with adjustments made to the PIB component to ensure adequate adhesion. By carefully selecting and balancing the molecular weights of these polymers, materials can be engineered to meet the specific demands for membranes, where both adhesion and durability are essential.

[0074] Polyisobutylene (PIB), for instance, is widely recognized for its inherent tackiness, which is directly influenced by its molecular weight. Low molecular weight PIB tends to be more tacky and sticky, making it highly effective as an adhesive component in self-sealing applications. This tackiness is due to the fact that lower molecular weight polymers have shorter chains, which allows them to flow more easily and interact with surfaces at the molecular level, enhancing adhesion. In blends where PIB is a key component, such as PIB with HR or PIB with BIMS, selecting a PIB with an appropriately low to medium molecular weight is essential for achieving the desired level of tackiness. However, if the molecular weight is too low, the material may become too soft or fluid, potentially compromising its structural integrity and long-term performance.

[0075] Isobutylene-lsoprene Rubber (HR), or butyl rubber, also exhibits properties that vary with molecular weight. Higher molecular weight HR tends to be more elastic and durable, which is beneficial for applications requiring long-term flexibility and resistance to environmental factors. However, to maintain adequate tackiness and adhesion when blended with PIB or BIMS, a balance must be struck. Typically, a medium molecular weight HR is chosen to ensure that the material retains sufficient elasticity without sacrificing the adhesive properties conferred by PIB or BIMS. In the case of HR’s blend with BIMS, the molecular weight of HR can influence how well the rubber interacts with the brominated segments of BIMS, affecting both the blend’s adhesion and its resistance to thermal degradation.Brominated Isobutylene-lsoprene Rubber (BIMS), due to its bromination, has a different set of molecular interactions compared to PIB or HR. The molecular weight of BIMS affects its cross-linking density, which in turn influences the adhesive properties and thermal stability of the blend. Higher molecular weight BIMS provides greater thermal stability and chemical resistance, which is important in applications where the membrane will be exposed to heat or aggressive chemicals. However, if the molecular weight is too high, it may reduce the tackiness of the blend, making it less effective as a self-sealing material. Therefore, when blending BIMS with PIB or HR, a medium molecular weight is often preferred to balance adhesion with durability.

[0076] Ethylene Propylene Diene Monomer (EPDM) and Ethylene Propylene Rubber (EPM) are known fortheir excellent weather resistance, which is largely unaffected by variations in molecular weight. However, molecular weight still plays a role in determining the mechanical properties of these materials. Higher molecular weight EPDM or EPM provides greater tensile strength and elasticity, which is beneficial for maintaining the structural integrity of membranes. In blends where EPDM or EPM is combined with PIB, a lower molecular weight for PIB might be chosen to enhance tackiness, while the EPDM or EPM remains at a higher molecular weight to ensure durability and flexibility. This combination allows the blend to be both adhesive and resilient, providing long-lasting performance in outdoor environments.

[0077] In one or more embodiments, the membrane is supported by the insulation material and / or the open-sided profiles and is not fastened to the shell and / or roof.

[0078] Reinforcement net

[0079] In one or more embodiments, the insulating cladding system further comprises a reinforcement net placed between the insulation material and the membrane.

[0080] The use of reinforcement nets either below or integrated within the membrane of is used to enhance the mechanical properties and durability of the insulating cladding system. These reinforcement nets provide additional tensile strength, dimensional stability, and resistance to punctures or mechanical stresses that may arise during installation, operation, or environmental exposure. By reinforcing the membrane, theoverall integrity is improved, reducing the risk of cracks, tears, or deformations that could compromise the tank’s ability to resist water ingress.

[0081] Reinforcement nets can be placed beneath the membrane to create a supportive substrate that helps distribute loads and resist tank movements, such as settlement or thermal expansion and contraction. Alternatively, reinforcement nets can be embedded within the membrane itself, forming a composite structure that combines the flexibility and impermeability of the polymeric sheet material with the added strength and stability of the reinforcement.

[0082] The choice of materials for such reinforcement nets is critical to ensuring compatibility with the membrane and achieving the desired performance characteristics. Suitable materials for reinforcement nets include high-strength synthetic fibers, such as polyester (PET), polypropylene (PP), and polyethylene (PE), which offer excellent chemical resistance, durability, and compatibility with polymeric membranes. In addition, fiberglass reinforcement can be considered due to its superior tensile strength and resistance to temperature variations, making it particularly suitable for demanding environments.

[0083] The type of reinforcement net used can vary depending on the application requirements. Common configurations include woven fabrics, which provide uniform strength in multiple directions; non-woven geotextiles, which offer high elongation and flexibility; and grid-like structures, such as biaxial ortriaxial grids, which provide excellent load distribution properties. The selection of the appropriate reinforcement type depends on factors such as expected load conditions, environmental factors, and the specific membrane material used.

[0084] In one or more embodiments, the reinforcement net is mounted to only the top faces of the open-sided profiles, preferably by fasteners, such as screws, nails, anchors, and bolts.

[0085] Hydrocarbon-resistant coating

[0086] The application of a hydrocarbon-resistant coating on the top surface of the membrane, when used for oil storage tanks is important to ensure structuralintegrity. Oil storage tanks, which are widely employed in the petrochemical, transportation, and energy industries, are subjected to significant exposure to hydrocarbon gases escaping from vents. These vents are necessary to prevent the buildup of excessive pressure inside the tank due to temperature fluctuations and the filling or emptying of liquid contents. Without proper venting, pressure imbalances could lead to structural damage or even catastrophic failure of the tank. However, these vents allow the escape of vapours, which contain volatile organic compounds, such as benzene, toluene, ethylene, and various alkanes. These vapours present numerous challenges to the materials used in tank construction and sealing membranes. Without adequate protection, these materials are prone to permeation and swelling, leading to mechanical degradation and potential failure. Prolonged exposure to hydrocarbon gases can also result in chemical breakdown, ultimately reducing the lifespan of the membrane.

[0087] Applying a hydrocarbon-resistant coating to membranes mounted on oil tanks provides a barrier against these challenges. The coating acts as both a physical and chemical shield, preventing hydrocarbon gases from permeating through the membrane. This enhances chemical resistance and preserves the membrane’s mechanical integrity, even in fluctuating temperature and pressure conditions.

[0088] Various coating materials have been identified as effective solutions for protecting membranes in hydrocarbon-rich environments. Epoxy coatings offer excellent adhesion, chemical resistance, and durability, forming a rigid, impermeable layer that effectively resists hydrocarbons. However, epoxies can become brittle over time and may require additional flexibility in dynamic environments. Polyurethane coatings provide exceptional flexibility, abrasion resistance, and resistance to a broad range of hydrocarbons, making them particularly suitable for applications where the membrane is subject to movement or mechanical stress. Fluoropolymer coatings, such as polytetrafluoroethylene (PTFE) and ethylene chlorotrifluoroethylene (ECTFE), provide superior resistance to hydrocarbons, solvents, and high temperatures. Their extremely low permeability makes them ideal for long-term applications in harsh conditions, although they are generally more costly compared to epoxies and polyurethanes and may require specialized application processes.In one or more embodiments, the membrane is coated with a hydrocarbon-resistant coating, the coating comprising, for example, an epoxy, polyurethane, or fluoropolymer composition.

[0089] The membrane may in some embodiments be coated with a specialized coating composition, such as the ones disclosed in EP3532544. The application of such a coating enhances the performance characteristics of the membrane by providing additional protective properties, such as improved resistance to environmental factors including moisture, chemicals, and mechanical wear. The coating composition described in EP3532544, hereby incorporated by reference, is particularly beneficial as it offers a combination of flexibility, durability, and barrier properties that complement the underlying insulation material. By utilizing this coating, the membrane gains enhanced resistance to degradation overtime, ensuring prolonged operational efficiency and reliability, especially in demanding environments such as oil and gas tanks.

[0090] The coating compositions disclosed in EP3532544 comprise a polymer dispersion comprising (of 100 parts per weight of dispersed material):

[0091] - 70-90 parts per weight of acrylate polymer,

[0092] - 5-15 parts per weight of aggregate particles, and

[0093] - 0.1-5 parts per weight of coagulator, which is silicon dioxide, hydrophobic silicon dioxide or a mixture thereof.

[0094] In this context, the term “acrylate polymer” refers to polymers and copolymers prepared from acrylic acid or its esters. Thus, here “acrylate polymers” also include acrylate copolymers. In the present context, the term “aggregate” means a substance which is added in a solid and preferably finely divided form, for example as powder, granules or particles, into a polymer solution. The aggregate may be partly or completely soluble in the liquid phase, i.e. the aqueous phase, but most of the aggregate may also be in solid form in the dispersion. The aggregate is generally an inorganic substance, most suitably an oxide compound or a sulphate compound, such as a metal or semi-metal oxide or sulphate, or a mixture thereof. The metals include aluminium, gallium and tin, and transition metals such as iron, copper, zinc, chromium, vanadium, nickel, titanium and zirconium. The semi-metals include silicon, germanium and antimony.It is also possible to use corresponding hydroxide compounds which are either insoluble or poorly soluble in water. According to one embodiment at least some of the aggregate particles have an average size of 0.01-0.2 pm, especially approximately 0.02-0.15 pm. Most suitably, at least 1 % by weight, especially approximately 2.5-50 % by weight of the aggregate, consists of such particles. According to one embodiment, at least some of the aggregate particles have an average size of 0.2-7.5 pm, especially approximately 0.5-5 pm, for example 1-3 pm. Most suitably, at least 1 % by weight, especially approximately 2.5-50 % by weight of the aggregate, consists of such particles.

[0095] To promote the formation of a film, a coagulator is used, i.e. a “precipitant”, which provides a structure which is cross-linked in a controlled way. According to one embodiment of the present invention, a film is formed of the dispersion by removing moisture, i.e. by allowing the dispersion, which is spread to form a layer, to dry. The coagulator and optional surface-active agent interact in such a manner that the evaporation of the liquid phase of the dispersion, while the coating dries, leads to a situation in which the surface-active agent is no longer capable of keeping the polymer particles of the dispersion apart, by means of electrical repulsion forces, and the polymer particles are cross-linked and form a solid structure in which the polymer matrix includes aggregate particles and coagulator particles.

[0096] One suitable example of such a coating composition is marketed under the tradename ElaProof PRO S.

[0097] Skirts and skirt cover

[0098] The skirts of a large oil storage tank, referring to the connections between the steel plates that make up the cylindrical shell, play a crucial role in maintaining the tank’s structural integrity and safety. These connections, formed through precise welding techniques, ensure the tank can safely contain liquids under a variety of conditions while distributing stresses evenly across its structure.

[0099] The cylindrical shell of a storage tank is constructed using steel plates arranged in horizontal layers called courses. These plates are connected at their edges both vertically, between plates within the same course, and horizontally, between one course and the next. The vertical connections are critical for aligning the plates toform a smooth, continuous cylinder, and they must withstand axial stresses from the weight of the oil and environmental forces, such as wind. The horizontal connections, meanwhile, are designed to handle the significant circumferential stresses resulting from the hydrostatic pressure exerted by the stored liquid, which increases with depth.

[0100] One particular challenge in creating horizontal seams is managing the transition between plates of varying thicknesses. In most tanks, the plates near the base are thicker to withstand higher pressures, while the upper plates are thinner to reduce weight and material costs. Welding these plates requires special bevelling techniques and multi-pass welding processes to ensure strong, reliable joints.

[0101] Residual stresses introduced during welding are carefully managed through techniques such as preheating, post-weld heat treatment, and stress-relief procedures, which are critical for maintaining the tank’s structural stability.

[0102] In addition to strength and alignment, the skirts must provide a liquid-tight seal to prevent leaks. The weld seams are inspected rigorously using advanced nondestructive testing methods, such as ultrasonic testing, to verify their quality and integrity. These welds are also susceptible to corrosion due to differences in metallurgical properties between the weld metal and the surrounding steel.

[0103] Protective measures, including specialized coatings, cathodic protection systems, and the use of corrosion-resistant alloys, are employed to safeguard these areas.

[0104] The skirts also play a vital role in accommodating the thermal expansion and contraction of the steel caused by temperature fluctuations. This flexibility is particularly important in tanks with insulation, where temperature gradients can create localized stresses. Enhancements, such as double-welded seams and the addition of reinforcement rings or stiffeners, further reduce strain on the skirts and improve their performance.

[0105] Despite these measures, skirts remain a focal point for inspection and maintenance. Regular monitoring using techniques like radiography or magnetic particle testing ensures that any defects, such as cracks or signs of corrosion, are detected and addressed promptly.In one or more embodiments, wherein when the shell comprises skirts, the insulating cladding system may further comprise a skirt cover positioned above the insulation material and below the membrane, thereby functioning as a support for said membrane.

[0106] The skirt cover is an external structure typically constructed from durable materials, such as treated wood, metal, or composite panels. Its primary function is to protect the insulation around the skirts of the tank while providing a rigid support framework for the membrane. The skirt cover is mounted securely around the circumference of the tank at the level of the skirts, often designed to accommodate the thermal expansion and contraction of both the tank and the materials it encloses. It is engineered to withstand environmental stresses, such as wind loads, precipitation, and temperature fluctuations, ensuring long-term stability.

[0107] The use of wood as the material for the skirt cover is due to its workability, thermal properties, and potential for creating a lightweight yet robust structure. The wood is typically treated to resist moisture, decay, and insect damage, extending its lifespan in outdoor conditions

[0108] In one or more embodiments, the skirt cover is mounted to only the top faces of the open-sided profiles, preferably by fasteners, such as screws, nails, anchors, and bolts.

Claims

Claims1. A storage tank for holding a fluid, the tank comprising:- a shell;- a roof fixed to the shell; and- an insulating cladding system;wherein the insulating cladding system comprises:- a plurality of open-sided profiles, preferably customizable, fastened to the shell and / or roof; wherein the open-sided profiles each comprises a top face, a bottom face, a first side face connecting the top and bottom faces, and an open side face positioned opposite to the first side face; and- one or more layers of insulation material mounted between, above, and preferably within, the open-sided profiles;characterized in that the insulating cladding system further comprises a membrane of a polymeric material, preferably unvulcanised, placed above the insulation material.

2. The storage tank according to claim 1 , wherein the insulating cladding system further comprises a reinforcement net placed between the insulation material and the membrane.

3. The storage tank according to claim 2, wherein the reinforcement net is mounted to only the top faces of the open-sided profiles, preferably by fasteners, such as screws, nails, anchors, and bolts.

4. The storage tank according to any one of the claims 1-3, wherein the membrane is coated with a hydrocarbon-resistant coating, the coating comprising, for example, an epoxy, polyurethane, or fluoropolymer composition.

5. The storage tank according to any one of the claims 1-4, wherein the one or more layers of insulation material is in the form of rigid batt insulation, such as mineralbased rigid batt insulation or foam-core rigid batt insulation.

6. The storage tank according to any one of the claims 1-5, wherein when the shell comprises skirts, the insulating cladding system further comprises a skirt coverpositioned above the insulation material and below the membrane, thereby functioning as a support for said membrane.

7. The storage tank according to claim 6, wherein the skirt cover is mounted to only the top faces of the open-sided profiles, preferably by fasteners, such as screws, nails, anchors, and bolts.

8. The storage tank according to any one of the claims 1-7, wherein the distance between side faces of neighbouring open-sided profiles is within the range of 10-150 cm, preferably within the range of 25-100 cm.

9. The storage tank according to any one of the claims 1-8, wherein a first group of the open-sided profiles are arranged in parallel alignment with one another.

10. The storage tank according to claim 9, wherein a second group of open-sided profiles are arranged in parallel alignment with one another and positioned within the interspaces between the profiles of the first group, and wherein the second group of profiles is oriented non-parallel, preferably perpendicularly, relative to the first group of profiles, thereby forming an intersecting pattern, e.g., a grid-like pattern.

11. The storage tank according to any one of claims 1-10, wherein the open-sided profiles are adhered to the shell and / or roof by an adhesive.

12. The storage tank according to claim 11 , wherein the open-sided profiles are adhered to the shell and / or roof without penetrating the shell and / or roof.

13. The storage tank according to any one of claims 1-12, wherein the open-sided profiles are configured such that movement of the shell and / or roof is absorbed at the bottom face of the profiles by flexing and / or sliding and / or deformation, while the top face of the profiles remains substantially position-stable relative to said movement.

14. The storage tank according to any one of claims 1-13, wherein the membrane has a thickness of 2 to 4 mm.

15. The storage tank according to any one of claims 1-14, wherein the membrane comprises polyisobutylene (PIB) and / or butyl rubber.

16. The storage tank according to any one of claims 1-15, wherein the membrane is not directly fastened to the shell and / or roof.

17. The storage tank according to any one of claims 1-16, wherein each open-sided profile is positioned such that the bottom face faces the shell and / or roof and the top face faces away from the shell and / or roof, and wherein the bottom face is configured to flex and / or slide and / or deform relative to the shell and / or roof while the top face remains substantially position-stable.

18. The storage tank according to claim 17, wherein the open side face is oriented laterally.

19. A method of insulating a storage tank for holding a fluid, the method comprising: - providing a storage tank comprising a shell and a roof fixed to the shell;- fastening a plurality of open-sided profiles, preferably customizable, to the shell and / or roof; wherein the open-sided profiles each comprises a top face, a bottom face, a first side face connecting the top and bottom faces, and an open side face positioned opposite to the first side face;- mounting one or more layers of insulation material between, above, and preferably within, the open-sided profiles; and- mounting a membrane of a polymeric material, preferably unvulcanised, above the insulation material.

20. The method according to claim 19, wherein fastening the plurality of open-sided profiles comprises adhering the open-sided profiles to the shell and / or roof using an adhesive.

21. The method according to claim 20, wherein the open-sided profiles are adhered without penetrating the shell and / or roof.

22. The method according to any one of claims 19-21, wherein each open-sided profile is positioned such that the top face is arranged to face away from the shell and / or roof for supporting the insulation material and / or the membrane.

23. The method according to any one of claims 19-22, wherein the open-sided profiles are configured such that movement of the shell and / or roof is absorbed at the bottom face of the open-sided profiles by flexing and / or sliding and / or deformation while the top face remains substantially position-stable.

24. The method according to any one of claims 19-23, further comprising placing a reinforcement net between the insulation material and the membrane, and fastening the reinforcement net only to the top faces of the open-sided profiles.

25. The method according to any one of claims 19-24, wherein, when the shell comprises skirts, the method further comprises positioning a skirt cover above the insulation material and below the membrane, thereby supporting the membrane.

26. The method according to claim 25, wherein the skirt cover is mounted only to the top faces of the open-sided profiles.