Patent Application
20190120383
The present invention relates to arrangements for providing a substantially fluid-tight seal. More specifically, a gasket arrangement for providing a fluid-tight seal between two mating surfaces is described. A panel for a sectional tank is also described.
Aspects and embodiments of the present invention are set out in the appended claims. These and other aspects and embodiments of the invention are also described herein.
According to a first aspect there is provided a gasket arrangement for a mating surface, comprising: a first member and a second member, the second member being arranged at least in part to provide a fluid-tight seal about the first member; wherein the second member is capable of deforming the first member while maintaining the fluid-tight seal when compressed; such that the gasket arrangement is capable of providing a substantially fluid-tight seal between the mating surface and a corresponding mating surface.
Thus, described herein is a gasket arrangement for providing a substantially fluid-tight seal between at least two corresponding mating surfaces in a sectional tank. Preferably, the arrangement comprises a first member and a second member, with the second member being arranged at least in part to provide a fluid-tight seal about the first member so as to inhibit fluid contact by fluid from within the sectional tank with the first member. Preferably, the second member is capable of deforming the first member while maintaining the fluid-tight seal when compressed.
By arranging the first member on the mating surface to be at least in part sealed by the second member, undesired movement of the first member may be inhibited during transit. Undesired movement of the first member when located between the two mating surfaces may also be inhibited when compressed together.
Thus, there is provided a simple gasket arrangement for providing a fluid-tight seal at a joint between two surfaces, which may also protect substrates having mating surfaces from degradation through chemical attack and/or corrosion.
By arranging the second member to be capable of deforming the first member (when compressed) while maintaining a fluid-tight seal about the first member, the first member may comprise any material suitable for performing the function of a gasket (but which is not necessarily robust against contamination) because the fluid-tight seal provided by the second member may inhibit contamination of the first member (for example, against chemical reactions such as corrosion), and optionally also the substrate beneath.
Preferably, the second member is capable of being deformed so as to deform the first member while maintaining the fluid-tight seal. The first member is preferably more compressible than the second member.
In addition to the exemplary applications described herein, the gasket arrangement may also be particularly useful for joining two mating surfaces in undersea applications due to the avoidance of the need to align a gasket and/or apply a sealant ‘on site’ when conditions (especially if underwater) may make it difficult to provide a good seal.
The second member is preferably arranged to be applied to the mating surface as a coating. For example, the second member may be coated onto the mating surface in the form of paint, or a similar substance, which dries onto the mating surface to form the coating, which is preferably in solid form. The second member is preferably arranged to completely cover the first member when provided on a mating surface. Optionally, the second member may be arranged substantially to encapsulate the first member.
The second member preferably comprises a flexible material, which may be an elastomeric material. Preferably, the second member may comprise at least one of: a rubber, silicon, a resin, a polymer and an acrylic. Optionally, the second member may comprise at least one of the following materials: polyuria; polyurethane; a hybrid of polyuria and polyurethane and a chlorinated rubber.
The thicknesses of the first and second members may vary according to the particular application of the gasket arrangement. However, the first member preferably has a thickness less than 20 mm, and preferably a thickness of between 0.1 mm and 20 mm. The second member preferably has a thickness of less than 10 mm, and preferably between 0.1 mm and 10 mm. As used herein, the term “thickness” preferably connotes the height of a member, rather than its width or length.
The first member may be arranged as a substantially elongate member, preferably having an elongate shape. Optionally, the first member may be arranged in as a strip.
The first member may comprise any material that may be compressed, preferably by at least 10% of its initial thickness. The first member preferably comprises a readily-compressible material, such as a foam-based material. Optionally, the first member may comprise at least one of: neoprene; polystyrene; polyurethane; ‘soft’ rubber; and cork; metal; rubber; plastic; silicon; graphite; resin; rubber; polyethylene; and PTFE. The first member may be arranged as tape, a pre-cut material or an applied bead of material, for example.
According to another aspect there is provided a surface having provided thereon a gasket arrangement as described above. At least of said surface may be arranged to be a mating surface, for example a surface arranged to be mated with another surface.
The second member is preferably arranged as a coating on at least part of the surface, preferably wherein at least part of the surface is arranged to be a mating surface. The coating preferably covers substantially the entire surface.
An exposed surface of the second member is arranged such that it does not adhere to another surface, preferably wherein it does not readily-adhere to another surface, for example wherein the exposed surface of the second member does not exhibit adhesive properties.
The first member is preferably arranged on the surface such that it is covered by the second member, preferably wherein the first member is arranged to be in direct contact with the surface. The first member may be adhered to the surface using a permanent adhesive, such that the first member cannot be removed from the surface without damaging the first member.
Optionally, the first member may be encapsulated by the second member, which second member may therefore be arranged to be in direct contact with the surface, preferably as a coating that covers the entire surface.
The first member may be arranged around at least a portion of the perimeter of the surface. Preferably, the first member is arranged around substantially the entire perimeter of the surface.
A plurality of holes may be provided through at least part of the surface for receiving securing means, for example bolts, for securing the surface to another surface having a corresponding plurality of holes.
According to another aspect there is provided a method of forming a gasket arrangement on a mating surface, comprising: arranging a first member and a second member on the mating surface, the second member being arranged at least in part to provide a fluid-tight seal about the first member; wherein the second member is capable of deforming the first member when compressed while maintaining the fluid-tight seal; such that the gasket is capable of providing a substantially fluid-tight seal between the mating surface and a corresponding mating surface.
Thus, described herein is a method of forming a gasket arrangement for providing a substantially fluid-tight seal between two corresponding mating surfaces in a sectional tank. Preferably, the first member and second member are arranged on at least one of the mating surfaces, the second member being arranged at least in part to provide a fluid-tight seal about the first member so as to inhibit fluid contact by fluid from within the sectional tank with the first member. Preferably, the second member is capable of deforming the first member when compressed while maintaining the fluid-tight seal.
Preferably, the first member is more compressible than the second member. The first member may be provided directly onto the mating surface before it is at least in part sealed by the second member. Preferably, the first member is adhered directly onto the mating surface prior to being at least in part sealed by the second member. Optionally, the first member may be adhered directly onto the mating surface using an adhesive that provides only a temporary adherence, whereby to provide a temporary bond for retaining the first member in position until at least in part sealed by the second member, for example until the coating of the second member dries, before the adhesive fails.
The second member may be arranged as a coating on the mating surface. Optionally, the second member may be arranged to cover the mating surface prior to arranging the first member on the mating surface.
According to another aspect there is provided a method of providing a substantially fluid-tight seal between two mating surfaces, comprising: providing on a first mating surface a gasket arrangement as described above; aligning the first mating surface with the second mating surface; and compressing the first mating surface and second mating surface together, such that the first member of the gasket arrangement deforms to provide a substantially fluid-tight seal between the two surfaces. In this way, the second member may act to inhibit any fluid contact with the first member.
Preferably, the method can provide a substantially fluid-tight seal between two corresponding mating surfaces in a sectional tank. The first mating surface may be secured to the second mating surface, preferably wherein the first mating surface and second mating surface each have a corresponding plurality of holes arranged to receive securing means therethrough, for example bolts, when the two mating surfaces are aligned.
According to another aspect there is provided a panel for a sectional tank, comprising a gasket arrangement or a surface as described above and/or being formed by a method as described above. The term “tank” preferably includes other types of vessels, and containers that are suitable for holding a fluid. A plurality of panels may be assembled to form a sectional tank. A panel may be a modular subunit for forming a sectional tank. A panel may be for assembly with fixings such as bolts.
The first member may be provided at or adjacent a perimeter of the panel. Preferably, the panel has a plurality of mating surfaces, wherein a first member of the gasket arrangement may be provided on each of said mating surfaces, the first member being covered by the second member of the gasket arrangement. The first member may be arranged to extend the entire length of a mating surface to be mated. The first member preferably extends along the mating surface substantially around the entire perimeter of the panel. The second member is preferably arranged to cover substantially the entire surface of the panel, said entire surface being the surface on which is provided the first member of the gasket arrangement.
According to another aspect there is provided a sectional tank comprising one or more panels as described above. While a panel for a sectional tank is herein described in detail, it should be understood that a panel for a sectional tank is simply a preferred embodiment. There may be many different applications that benefit from having a gasket arrangement as described herein, including: pipe and valves; doors and closures; matched machine parts; and modular buildings, to name but a few examples.
According to another aspect there is provided a sectional tank constructed using a plurality of panels joined together using a method as described above, preferably wherein at least one of the panels is a panel as described above.
According to another aspect there is provided a pipe having a surface as described above, preferably wherein the surface is arranged at an end of the pipe, optionally on a flanged portion.
According to another aspect there is provided a valve arrangement having a surface as described above, for example a butterfly valve for connection between two pipes.
According to another aspect there is provided a door and a doorframe arrangement comprising a surface as described above. A door is simply one example of an opening; a hatch or other similar arrangement may also have such a surface.
According to another aspect there is provided a panel for a sectional tank, the panel comprising a base member having an elastomeric coating. Optionally, the panel may be a sectional tank panel.
Preferably, the elastomer (of the elastomeric coating) is a polyurethane or a polyurea or a polyurethane/polyurea hybrid. These elastomers are particularly favourable because they combine favourable protective properties (and in particular are resilient to damage by chipping and cracking upon impact) and also display short curing times at room temperature (typically 20° C.). This can be advantageous for coating prior to assembly of the panels, which in turn can permit ease of construction of a functional tank. These elastomers also demonstrate particularly good adherence to a wide variety of materials of the base member. The coating is preferably applied prior to assembly into a sectional tank. Preferably, the elastomeric coating is adhered to at least part of the base member. Preferably, the elastomeric coating has an elongation <350% (preferably according to ASTM D12).
For protection against corrosion the coating may extend over a greater area (or region) than the area of the base member that forms, in use, the internal tank surface (e.g. of a sectional tank) when assembled. In other words, the coating may extend further than just area that forms the internal tank surface. Preferably, the coating extends over at least a face surface of the base member and at least an edge surface of the base member, and more preferably over all edge surfaces adjacent the face surface. The face surface is, preferably, the surface that will be arranged to face internally, in use, for example internal of a sectional tank formed by a plurality of said panels. Optionally, the base member may be completely encapsulated by the coating. The coating may extend over a defined portion of a surface of the base member, for example over at least one mating surface of the base member.
For ease of application and fast curing the coating may be applied by a spray application, and optionally a hot spray application.
The base member may comprise fibreglass, plastic or metal, preferably steel. Alternatively, the base member may comprise cement or concrete. The base member is preferably a non-foamed (or non-foam) material. The base member preferably comprises a substantially rigid material. Preferably, the base member is substantially homogeneously solid. Preferably, the base member is with no substantial interstitial spaces.
The panel may further comprise one or more anchor formations, where each anchor formation is partwise anchored in the coating and partwise anchored to the remainder of the base member. The one or more anchor formations may be formed of plastic or steel. The one or more anchor formations may comprise a cross-shaped (e.g. cruciform), profile.
Optionally, the coating may comprise a single layer of material. The coating may have a thickness of between 0.1 mm and 10 mm, preferably a thickness between 0.5 mm and 5 mm, and more preferably a thickness between 1 mm and 2 mm. Alternatively, the coating may comprise multiple layers of material, where the multiple layers are applied to the base member one over the other. The coating may be applied in multiple layers covering different areas of the base member. The multiple layers are preferably formed of the same elastomeric material/elastomer.
Preferably the elastomeric coating is substantially homogeneously solid. Preferably the elastomeric coating is a substantially homogeneous material. Preferably the elastomeric coating is with no substantial interstitial spaces. Preferably the elastomeric coating forms a spontaneous bond with the base member.
Thus, described herein is a panel for a sectional tank (e.g. a sectional tank panel), comprising a base member that is completely encapsulated by an elastomeric coating. Preferably, the elastomer (of the elastomeric coating) is a polyurethane or a polyurea or a polyurethane/polyurea hybrid. Preferably, the elastomeric coating comprises a spray-applied, fast-cure elastomer. When joining adjacent panels, when assembling/constructing a sectional tank on-site for example, a sealant (such as a polyurethane, silicone or poly-sulphide sealant, for example) may be used at the panel seams/overlaps and the holes for bolt penetrations, or other fastening means.
The panel may provide at least the following benefits over existing glass enamel coatings and epoxy coatings: the panel may be completely encapsulated due to the method of manufacture not requiring the (sectional) panels to be carried on hooks which can prevent application to all areas; due to the panels not needing to be heat treated and the elastomer/resin being fast-curing, the elastomeric coating can be applied to one side of the panel, and the panel then turned over (or the method of attachment changed) so as to allow application to the remaining areas; the protective coating can be applied to the edges of each panel (conventional manufacture of epoxy and glass enamel panels and the way they are produced on a production line mean that the edges may not be coated); the use of a sealant is for sealing purposes (i.e. between adjacent panels) only, not for providing corrosion protection of the panel edges as per glass enamel and epoxy coated sectional tanks; the flexible nature of the elastomeric coating mean that the panels are less susceptible to damage during transport and assembly; all of the above aspects may help to provide improved corrosion protection and extended life expectancy of the panels, and hence any structure formed by the panels, such as a sectional tank.
According to another aspect there is provided a method of coating a panel for a sectional tank, comprising: providing a base member; and providing an elastomeric coating over at least part of the base member. The coating may completely encapsulate the base member.
Preferably, the elastomeric coating is provided by applying a resin to the base member, which polymerises to form the elastomeric coating over said at least part of the base member. The resin may be applied by spraying. Optionally, the resin may be applied by hot spraying, preferably onto an unheated base member. The resin may be heated to a temperature between 65° C. and 85° C. The resin may be subjected to pressure greater than atmospheric pressure, preferably greater than 10 MPa, and more preferably greater than 20 MPa, for example during curing (of the resin).
The resin may be applied to a first portion of the panel while the panel is held at a second portion, and wherein subsequently the resin is applied to at least the second portion while the panel is held elsewhere than the second portion.
The resin may cure to form the elastomeric coating sufficiently quickly that coated panels may be further handled after application of the resin (e.g. such that the coating is “tack-free”) after less than 2 hours, preferably less than 1 hour, preferably less than 30 minutes, preferably less than 10 minutes, preferably less than 5 minutes, preferably less than 2 minutes, preferably less than 1 minute, preferably less than 30 seconds, and preferably less than 10 seconds.
Subsequent to application of the resin, a further layer of resin may be applied over the first layer. Subsequent to application of the resin, further resin may be applied to repair damage to the coating.
According to another aspect there is provided a method of producing a sectional tank panel, comprising: applying a resin to a mould for a panel, wherein the resin is such that it polymerises to form an elastomer; and casting a panel from the mould. The panel cast from the mould may comprise a concrete or cement base member having an elastomeric coating. The casting may comprise applying a cement or concrete mixture to the mould.
Preferably, the elastomer (of the elastomeric coating) is a polyurethane or a polyurea or a polyurethane/polyurea hybrid. Preferably, the resin comprises the elastomer and/or is configured (for example, contain the necessary components/ingredients) to form the elastomer when it polymerises.
One or more anchor formations may be partially embedded in the resin before the resin is polymerised. The one or more anchor formations may comprise a cross-shaped (e.g. cruciform) profile. The one or more anchor formations may comprise plastic or steel, for example.
The panel cast from the mould comprises a concrete base member having an elastomeric coating. The mould may be treated with release agent prior to applying the resin. Further resin may be applied to form a seal between two adjacent panels.
The elastomeric coating may be more deformable (e.g. compressible) than the base member. The coating is preferably arranged to cover at least part of the base member so as to protect it from exposure to any fluids, or chemicals, etc. to which it might otherwise be exposed, for example when used as a sectional tank for storage purposes.
According to another aspect there is provided a sectional tank panel produced according to the method described herein and/or a sectional tank comprising one or more panels as described herein.
According to another aspect there is also provided apparatus and/or methods substantially as herein described and illustrated in the accompanying drawings.
As used herein, the term “gasket” preferably connotes a seal that may be provided between two mated surfaces, matched machine parts or around pipe joints, for example, to prevent the escape or ingress of a fluid.
As used herein, the term “sealant” preferably connotes a material (or combination of materials) or substance used to provide a seal between two surfaces, such as a joint between two surfaces, and preferably a fluid-tight seal.
As used herein, the term “coating” preferably connotes a layer (e.g. a thin film) of a material or substance (or a covering) that may be applied to a surface of an object, preferably for protection of that surface. The coating may be an all-over coating, completely covering the surface, or it may only cover parts of the surface. Accordingly, the term “coated” preferably connotes having a coating.
As used herein, the term “member” preferably connotes a material or substance arranged to form a constituent part of a composite whole. As used herein, the term “elongate shape” preferably connotes a shape that is much longer than it is wide. As used herein, the term “strip” preferably connotes a flattened elongate shape, for example a long narrow piece or section of material.
As used herein, the term “fluid” preferably connotes liquids, gases and flowable solids, such as grains, for example.
As used herein, the term “elastomer” preferably connotes a polymer having, for example, at least one of the following properties:
Any apparatus feature as described herein may also be provided as a method feature, and vice versa. As described herein, structural features may be expressed alternatively in terms of means plus function. Any, some and/or all features in one aspect may be applied to any, some and/or all other aspects, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. It should also be appreciated that particular combinations of the various features described and defined in any aspects can be implemented and/or supplied and/or used independently.
One or more exemplary embodiments will now be described with reference to the accompanying figures, in which similar features may be identified using similar reference numerals, and in which:
Conveniently, sectional tanks can be transported to an intended site in disassembled form (e.g. as individual panels or sections) and then (re)assembled on site. Sectional tanks are commonly used for storing large volumes of fluid (e.g. water), and are particularly convenient for applications where access is restricted. Once assembled, it is typically undesirable to transport a sectional tank, which may therefore be considered to be a (semi) permanent structure requiring disassembly for relocation.
A fluid-tight seal may be provided between adjacent/adjoining panels by applying a sealant to a mating surface (e.g. part of the surface along the edge or at the perimeter) of a panel and then overlaying it with a corresponding mating surface of another such panel before applying a compressive pressure to the panels to seal across the joint that has been formed. The panels may then secured together using bolts or other suitable securing means.
To avoid the sealant becoming contaminated, disturbed, damaged or removed during transport, the sealant is ideally applied onto the mating surface of the panels on site immediately before they are joined together, rather than before the panels are shipped or otherwise transported to site.
If insufficient sealant is applied, the resulting joint may not have the required integrity to provide a fluid-tight seal, for example. In addition, care must be taken to avoid sealant leaking out from between the joint, which may otherwise have the same effect of inadequate sealant being provided between the joint. Alternatively, a separate gasket component may be provided, but this requires aligning on the panel on site prior to joining the panels and may become misaligned during the joining process.
Should the integrity of a seal be inadequate, it could potentially cause a dangerous situation, depending on the location and purpose of the seal. At the very least, remedial work may need to be undertaken to repair (or even replace) the sealant, which will require time and resources.
The panel 114 has a plurality of holes 118 for receiving bolts, or other suitable fixings, for securing two such panels 114 together, or to a framework (not shown). The holes 118 are spaced along vertical and horizontal seams generally located at or towards the perimeter of each panel 114. The surface of the panel 114 immediately adjacent (e.g. on either side of) each row of holes 118 may be referred to as a mating surface 120. In use, the mating surface 120 of a panel 114 may be overlapped with the mating surface 120 of another such panel 114 to form a joint. The panels 114 can be secured together via the holes using bolts, for example, as mentioned above. The size and shape of a panel 114 may vary according to each specific application, though they are often rectangular for ease of tessellation. A panel 114 may comprise a base member, which may be made from fibreglass, plastic or metal (preferably steel), for example.
Two different embodiments of a gasket arrangement 122 will now be described, with reference to
In the example shown in
In the example shown in
In both
The first member 124 may be arranged to be more deformable/compressible than the mating surface 120 of the panel 114 and less deformable/compressible than the second member 126 that covers it. The first member 124 may be a flat, elongate shape arranged to extend along an edge of the panel 114. The first member 124 may be formed of a foam-based material (such as a hard closed-cell PVC foam, for example) or it may be formed of another such ‘readily compressible’ material.
The second member may be applied as a coating on the surface of the panel 114. The second member 126 is preferably arranged to cover substantially the entire surface of the panel 114. The second member 126 may be more deformable (e.g. compressible) than the panel 114. The second member 126 is arranged to cover the first member 124 so as to protect it from exposure to any fluids, or chemicals, etc. that it might otherwise be exposed to, for example when used with a storage tank 100. The second member 126 may be provided as an elastomeric coating, or similar, preferably formed from a material that is resistant to chemicals. Ideally, the second member 126 is arranged to be sufficiently flexible that it can be deformed under compression (e.g. when securing two panels 114 together) while maintaining a fluid-tight seal about the first member 124 without cracking, tearing, rupturing or otherwise losing its structural integrity.
When the two panels 114A, 114B are secured together, the first member 124 of the gasket arrangement 122 is compressed such that it deforms to a greater extent than the second member 126, thereby acting as a gasket between the panels 114A, 114B to seal the join. The second member 126 is sufficiently flexible so that, when the gasket arrangement 122 is compressed, the second member 126 allows deformation of the first member 124 while maintaining the fluid-tight seal about the first member 124 without rupture. Thus, the second member 126 protects the first member 124 from coming into physical contact with the contents of the sectional tank or other contaminants, once constructed and in use.
Furthermore, the second member 126 protects the first member 124 from being dislodged, both when the two panels 114A, 114B are initially aligned and/or secured together, and when in use.
The gasket arrangement 122 may be used in a sectional tank 100 to provide perimeter seals and partition seals, preferably between adjacent panels 114. It should be understood that a gasket arrangement 122 on a panel 114 for constructing a “sectional tank” is simply a preferred embodiment.
Sometimes it is necessary to protect panels from corrosion, for example if used to construct a sectional tank intended to contain corrosive material. Protective coatings can enable the use of materials such as steel for the panels, which would otherwise suffer corrosion in use. Typically, a protective coating would be applied to the interior of a sectional tank after assembly, for this purpose. However, applying a coating after assembly adds a further step in the construction process, and thereby detracts from the intended convenience and ease of constructing a sectional tank.
Applying a glass enamel or epoxy coating to panels prior to assembly (for example in a central processing facility) of a sectional tank, or similar, may help to protect such panels against corrosion. Advantageously, these coatings can be applied to panels on a production line, rather than on site. However, whilst such glass enamel or epoxy coatings may offer protection against corrosion, they perform poorly when subjected to impact. Thus, the necessary handling and transport of coated panels can often result in damage to the coatings on one or more of the panels, causing exposure of the steel beneath which can lead to panel corrosion and eventual perforation and failure.
Furthermore, the application of glass enamel and epoxy coatings includes a heat curing step, and consequently the process of manufacture is relatively energy intensive. The coating materials for glass enamel and epoxy coatings are applied in liquid form and remain wet until heat cured. Typically, a base member of a panel is suspended from hooks and transported during the coating procedure (including applying the coating materials and heat curing). In the areas where the base member is in contact with the hooks the liquid coating materials are not or only poorly applied and hence the coating may fail to protect the base member in those regions. The portions of the panels that are inadequately coated can be protected against corrosion by the application of a sealant on site.
This process can however contribute to potential weakness/flaws in the anti-corrosion properties of the coating. Not only are the areas where a base member is in contact with the hooks poorly coated, but also the edges of a base member can be poorly coated as typically the liquid coating material is only applied on one face of a base member. If so, the edges also rely on protection via the application of a sealant on site, which offers inferior corrosion protection. In addition, the heat curing step required for glass enamel and epoxy coatings may make it difficult to repair easily, on site, any damage to a coating.
Instead of a glass enamel or epoxy coating, a coating of an elastomer, optionally a polyurethane or a polyurea or a polyurethane/polyurea hybrid, may be applied to a base member (e.g. an underlying substrate) to form a panel in which the base member is protected against corrosion. In particular, elastomeric polyurethane and/or polyurea coatings are advantageous as they can offer improved resistance to mechanical damage.
Furthermore, elastomeric polyurethane and/or polyurea coatings require no heat curing during manufacture and so better manufacturing energy efficiency is possible. Elastomeric polyurethane and/or polyurea have fast gel/cure times, which may be in the order of minutes or even seconds, for example, and as such is convenient for manufacture. Elastomeric coatings such as polyurethane and/or polyurea may additionally be suitable for hot spray application, which permits further reduction of the curing or gelling time. Hot spray applied elastomer coatings can provide particularly favourable physical properties as well. Due to the absence of a heat curing step and the short curing or gelling time for the coating, different areas of a base member of a panel may be coated consecutively for complete encapsulation of a sectional panel, or layers can be built up for a thicker coating.
For example, one side of a base member may be coated whilst the opposing side is held, for example by a magnetic lifter (in an embodiment having a magnetic base member); alternatively a base member may be held at a top-left region for a first coating, and then the same base member may be held at a bottom/right region for a second coating so that both the faces and all edges are fully encapsulated for favourable corrosion protection. The base members are completely encapsulated by the coating in a factory environment prior to transportation and assembly of a sectional tank, for example, on site. Sealant may still be used for assembly of the panels to construct the tank, though the sealant need not be relied upon to provide corrosion protection, but only to form a fluid or gas tight seal.
Should the panel coating become damaged, then the elastomeric coating can easily be repaired on site as no heat curing step is required. The repair can use the same coating material, applied by a spray, or by brush/roller, for example.
The coating 224 may be provided directly on the surface of the base member 214. The coating 224 may be arranged to cover substantially the entire surface of the base member 210. The coating 224 is preferably arranged to cover at least part of the base member 210 so as to protect it from exposure to any fluids, or chemicals, etc. that it might otherwise be exposed to, for example when used with a storage tank 100.
The coating 224 is preferably more deformable (e.g. compressible) than the base member 210. The coating 224 may be formed from a material that is resistant to chemicals. Preferably, the coating 224 is arranged to be sufficiently flexible that it can be deformed under compression (e.g. when securing two panels 214 together) without cracking, tearing, rupturing or otherwise losing its structural integrity, for example to remain fluid-tight and prevent the ingress of fluid to the base member 210. This flexibility may also protect the coating from damage by impact.
In one example, the coating 224 may a polyurea (the reaction product of a polyisocyante component and an amine terminated resin blend). An example of a suitable pure polyurea for the coating is Polyshield HT-100F UB™ (an aromatic polyurea) from Specialty Products, Inc., Washington USA. The physical properties of a suitable pure polyurea coating are, for 1.7 mm coating thickness: tensile strength (ASTM D412)>27.11 MPa; elongation at 25° C.>300%; Shore hardness (D) 55; modulus at 100% elongation (ASTM D412)>11.13 MPa; modulus at 300% elongation (ASTM D412)>24.32 MPa; tear resistance (ASTM D624) 84.57 kN/m. A suitable pure polyurea typically has a gel time of approximately 5 seconds, and is tack free after approximately 7 seconds.
In another example, the coating may be an elastomeric polyurethane/polyurea hybrid coating (the reaction product of a polyisocyante component and a resin blend component, where the resin blend is made up of blends of amine-terminated and/or hydroxyl-terminated polymer resins). In another example, the coating may be an elastomeric polyurethane. An example of an elastomeric polyurethane for the coating is Polibrid™ 705E from AkzoNobel. The physical properties of a suitable elastomeric polyurethane coating are, for 0.7 to 5 mm coating thickness: tensile strength (ASTM D12)>19.3 MPa; elongation (ASTM D12) 43%; impact resistance (ASTM D2794)>72.5 kg (direct and reverse); Shore hardness (D)>60. A suitable elastomeric polyurethane typically is touch dry after approximately 1 hour at 25° C. or 2 hours at 15° C., and is hard dry after approximately 1 day at 25° C. or 2 days at 15° C. Such an elastomeric polyurethane can be applied by brush or roller, or by airless spray. Due to the shorter gel time and the more favourable physical properties a pure polyurea coating or a polyurethane/polyurea hybrid coating is preferred over a pure elastomeric polyurethane coating.
The spray process (also referred to as ‘plural spray process’) mixes separate resins or prepolymer components for example in a mixer block or by impingement in the spray gun. The benefit of spraying is that the time between mixing and application is minimal, and the materials can have a very short gel time, which means that after application the coating can be handled very quickly. Hot spraying further includes heating of the resins and/or mixture above ambient temperature. This can further minimise the gel time.
A typical hot spray procedure for a pure polyurea uses a prepolymer ratio of 1:1, a minimum pressure of 13.7 MPa (2000 psi) (physical properties are enhanced when sprayed at higher pressures, e.g. 20.8 MPa (3000 psi) or more) and heating up to 79° C. (with pre-heater temperature 71-76° C. and hose temperature 71-76° C.). A typical hot spray procedure for an elastomeric polyurethane uses a pre-polymer ratio of 2:1 with an airless spray having at least 20.8 MPa (3000 psi) output pressure.
The base member 110, 210 of the panels 114, 214 may be formed from concrete or cement. Concrete (or cement) panels can be useful as they can be pre-cast into a desired shape relatively cheaply, enabling tailor-made panels that can be assembled on site to form the desired sectional tank. Conventionally concrete panels for sectional tanks can be coated on site, after assembly into a tank. For coating such concrete panels it is also known to use HDPE sheeting, which is typically laid into a mould for casting a panel. The sheeting has a profiled pattern on the back. On site, the HDPE of adjacent panels is joined together by welding a strip between the panels. Sealing the coating around pipe penetrations and small features can be problematic, and achieving a good fluid tight weld can be difficult to achieve and difficult to test.
Thus, according to an embodiment, an elastomeric coating, as described above, may be provided on a concrete (or cement) base member to form a panel. The coated concrete panels can be produced as described now with reference to
On site when the coated concrete panels are installed to form a sectional tank, gaps between the panels are sealed by applying more of the coating material (in prepolymer resin form) to form a seamless bond between to the panels providing a fluid tight seal and also protecting the concrete substrate beneath. The seal can be tested for defects for example using a DC holiday spark tester.
A relatively small sectional tank may for example have an internal volume of at least and/or approximately 1 m3 (cubic metre), which for a cubic tank requires generally square panels of approximately 1 m×1 m dimensions, and for a fill with water for example a weight of over 1 metric ton. A sectional tank is typically larger than this, for example holding 5 m3, 8 m3, 10 m3, tens of cubic meters, hundreds of cubic meters, or over 1000 m3. The size of the panel may therefore vary depending on the size of the desired structure (e.g. tank) and/or the number of panels that are required to construct it. Thus, a panel as described herein may have a length (e.g. height) dimension in the range of between 1 m to 5 m, approximately, and a width (e.g. diameter) dimension in the range of between 1 m to 5 m, approximately. Of course, the panels are often rectangular, including square, but may be any other desired shape, preferably which shape allows for tessellation with other such panels.
In another example of a sectional tank (not shown), a skeletal framework may be provided, to which a plurality of panels are secured to construct a sectional tank.
The gasket arrangement and methods described herein may also be used to join a pipe flange, for example, or indeed various other mating surfaces.
It should be understood that the embodiments described above are provided purely by way of example, and modifications of detail can be made within the scope of the invention.
Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination. Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1604578.3 | Mar 2016 | GB | national |
| 1611507.3 | Jun 2016 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2017/050762 | 3/17/2017 | WO | 00 |
