METHOD FOR COVERING FLUID TANKS

Abstract

 Disclosed is a method for partially lining the inside of vertical-axis tanks (1) that are buried or the bottom base of which is partially buried, forming a partial intermediate or interstitial chamber between the fluid container and an outer wall of the tank (1), reducing the possibility of leaks to the environment outside the tank (1) and allowing them to be detected should they occur. The invention also comprises the lining for the vertical-axis tanks (1) that are buried or the bottom base of which is partially buried, wherein said lining comprises two laminar walls (3, 5) between which is located an interstitial chamber (4) that enables the detection of leaks of fluid stored in the tanks (1).

Description

OBJECT OF THE INVENTION AND TECHNICAL FIELD

[0001] The object of the present invention consists of a method which allows providing vertical-axis tanks, that are buried or the bottom base of which is partially buried, with an inner lining for said buried base, forming a partial intermediate or interstitial chamber between the fluid container and the outer wall of the tank.

[0002] The invention also comprises a lining for said type of tanks, which allows preventing and detecting the leaks of the fluid stored inside the tank to the outside, which can contaminate the environment in which said tank is located.

[0003] The invention is comprised in the sector of the industry dedicated to the engineering of storage of fluid products in tanks and reservoirs, more specifically to the industry dedicated to the manufacture, repair, or restoration and maintenance of tanks or containers for liquids and/or gases of petroleum origin, such as fuels and derivatives thereof.

[0004] These tanks are mostly made of a metallic material, steel with a high structural strength and reduced corrosion wear, where the lining can be used in tanks made of other materials, such as those manufactured in plastic, as long as they comprise characteristics similar to metallic steel tanks.

BACKGROUND OF THE INVENTION

[0005] Since fluid tanks for fuel, as well as derivatives thereof, are usually made of metallic materials or rigid plastics, in general, the continuous action over time of external and internal agents to which said tanks are subjected can cause the deteriorations of tank walls which can cause seepages with serious drawbacks of contaminating the environment in which the tanks are located.

[0006] Metallic tanks, plastic tanks, or tanks made of other materials with similar characteristics, intended for storing fuel and derivatives thereof, are known in the state of the art today, said tanks being provided with double-walled systems comprising an interstitial chamber located between two walls of the tank. This chamber allows preventing or reducing the leaks of stored fluid from the inside to the outside of the tank, as well as detecting possible fluid leaks by means of systems that are also known.

[0007] These leak detection systems already existing on the market allows informing of a possible leak in the tank with the emission of sound and/or visual signals when fluid enters the interstitial chamber, constituting a permanent and preventive control and protection system in tanks of this type.

[0008] In addition to providing a warning in the event of a leak between walls, the advantage of double-walled tanks over conventional single-walled tanks lies in the fact that, if a crack occurs in the internal layer, the spillage that occurs does not spill directly into the external environment, but rather into the intermediate chamber in the first instance. Similarly, the service life, both of the material forming the outer casing, which is better protected against corrosion gradually generated by the fluid contained in the tank over time, and of the stored fluid itself, which comes into contact with the internal wall, which has chemical properties suitable for storage, is protected and increased.

[0009] As an additional advantage, the double-walled tanks allow, in the event of accidental deterioration of the internal layer, a much easier and more economical repair or replacement of the internal layer, than if the entire outer casing of the tank had to be replaced.

[0010] As an alternative to tanks which comprise double wall by default, the state of the art discloses "in situ" restructuring of tanks from single- to double-walled tanks, for the purpose of improving storage safety, as well as applying or installing a permanent leak detection system, such as those existing in double-walled tanks, for old tanks that retain the initial structural performance. In other words, for those tanks with a single wall but which can store combustible fluids under certain pressure and temperature conditions.

[0011] This current technology of restructuring tanks from single- to double-walled tanks is particularly designed for horizontal-axis tanks that are buried completely, since by being buried, the detection of fluid leaks from the internal cavity to the outside by means of external visual inspections is extremely difficult.

[0012] The way for lining the inside of buried horizontal tanks of this type requires a series of steps in which the inner surface of the tanks must be completely covered, with the need to perform tasks which include cleaning, degassing, thickness measurement, as well as repair of any cracks or openings present.

[0013] In addition to these horizontal-axis tanks that are completely buried, there is a need to define a method which allows the partial restructuring of vertical-axis, single-walled tanks into double-walled tanks, when the bottom base of said tank is partially buried. This is due to the fact that it is also extremely difficult to detect leaks in said buried section from the outside, and furthermore the implementation of the system used for horizontal tanks is neither compatible nor necessary for tanks in which only a part thereof is buried.

[0014] In other words, it is not necessary to reinforce and cover the entire internal surface of the tank when merely a part thereof is buried. Therefore, the objective is set to partially cover an internal section of a tank which is covered, for the purpose of reducing seepages through said section, as well as enabling their detection if they occur.

[0015] With respect to the leak detection system, various methods for ensuring that the fluid retained in the tanks do not seep to the outside through non-localised holes or openings are known in the state of the art.

[0016] Said methods are often used in the field of fuel tank quality engineering, as part of the normal maintenance operations that tend to minimise economic and environmental costs derived from the appearance of fissures or cracks in the tanks, which can end up causing a significant spillage of the substance stored in the tanks, in addition to the collapse and necessary replacement of the tank.

DESCRIPTION OF THE INVENTION

[0017] The present invention consists of a method for lining an inner surface of a bottom section, or lower part, of a vertical-axis, aerial, atmospheric, single-walled fluid tank, wherein said section is completely or partially buried underground, wherein said method comprises the following steps:

• applying a primary laminar lining wall on the inner surface of the buried bottom section of the tank, covering said surface completely, maintaining its structure;
• applying a three-dimensional layer on the primary wall, covering said primary wall;
• applying a secondary laminar lining wall on the three-dimensional laminar fabric layer, covering said layer;

wherein the three-dimensional layer is located between the primary wall and the secondary wall, separating them completely, generating a hollow, and preferably monitored, interstitial chamber; and

wherein the bottom section, on which the lining walls and the laminar layer are adhered, comprises a bottom base and a side wall fraction of the tank which comprises, from the base of said tank, a height of up to between 20 and 120 cm with respect to said base.

[0018] Preferably, the height of the side wall of the tank at which the lining is fixed is 70 cm, being sufficient to safeguard and ensure the sealing of the entire base and part of the vertical side wall which is usually located below the ground in buried tanks of this type. It is considered that as a safety margin to prevent seepages in the wall of a semi-buried tank, it should be a minimum of 3% of the height of said wall, with 20 m being the maximum height of the vertical-axis tanks.

[0019] A height of 20 to 120 cm is used depending on the height at which the tank is buried, since it is recommendable to apply lining at a height that is somewhat greater than the height at which the tank is buried. In this way, if the tank is only buried 30 cm from its base, then a side wall height of 60 cm will be sufficient to cover the part of the buried base along with the part of the side wall of the tank that is also buried.

[0020] At most, semi-buried tanks of this types are often buried no more than 120 cm above its base, leaving the rest of the surface of the tank exposed to the outside, which will be visible, and it is not necessary to cover the inside with said walls more than necessary.

[0021] The described lining method allows the steps defined therein to be performed "in situ", without having to transfer or move the tank from the site in which it is located.

[0022] If required, a series of tasks can be performed prior to lining, such as cleaning and degassing the tank entrance chamber, cleaning any possible waste that may remain inside the tank, due to use, which can hinder the adhesion of the primary wall, degassing the fluid storage cavity, repairing defects that do not comply with the requirements set, puttying imperfections, as well as labours of checking the thicknesses of the surface for fixing to the primary wall.

[0023] Although the primary and secondary walls, as well as the three-dimensional layer, are placed inside of the tank, the method hardly causes any minimum reduction in the storage volume in the inner cavity of said tank. This is due to the fact that said primary and secondary walls have a laminar structure of negligible thickness compared to the volume of the internal cavity, and the three-dimensional layer comprises a thickness of about 1 cm, sufficient for the generation of the interstitial chamber, hence said laminar layer is defined as "three-dimensional".

[0024] Said laminar layer being hollow means that it allows the passage of fluid through the inside thereof, i.e., fluid can flow through the interstitial chamber, where said fluid can be a liquid or a gas such as air or another inert gas, being at defined pressure conditions.

[0025] A three-dimensional layer can be that which comprises hollow cavities therein that allow generating an air chamber therein by means of the described method. The pressure or volume loss inside this chamber can be measured by means of different leak detection methods, and therefore its leak-tightness can be checked.

[0026] Once the method has been completed with the placement of the secondary wall, it may be necessary to check the flexural strength of the generated interstitial chamber, such that the created lining has flexural strengths preferably equivalent to a 2 mm-thick S-275 steel, in order to prevent the pressure of the fluid inside the cavity of the tank from damaging it. Said equivalence can be demonstrated by means of standardised testing performed by a suitable personnel. Similarly, it is recommendable for the mechanical compressive strength of the lining of the installed double wall to be at least two times the hydrostatic pressure of the liquid stored in the tank under maximum fill conditions.

[0027] The material of the secondary wall, when in contact with the stored fluid, is suitable to comply with minimum chemical resistance parameters to prevent its degradation. Similarly, the primary and secondary wall layers must be completely compatible and the inside of the tank must provide an electrical resistivity of less than 10⁹ Ω.

[0028] Preferably, upon completion of the placement of each of the walls and layer, the thicknesses thereof can be measured for the purpose of verifying the uniformity of the thickness of the application along the surface of the tank. Furthermore, preferably, said measurement must be performed at least every 50 cm. If an area with a decrease in the necessary thickness is detected, a minimum amount conducive to achieving the required thickness value can be applied in said area.

[0029] In one embodiment, the method for lining the inside also comprises the steps of:

• sectorising the interstitial chamber, dividing said chamber into one or more sectorised interstitial compartments; and
• installing in each of these sectorised compartments a leak detection system configured to detect leaks in each of said sectorised compartments of the interstitial chamber with the primary wall and/or the secondary wall.

[0030] These steps are performed after applying the three-dimensional layer and preferably before placing the secondary wall on said layer.

[0031] Preferably, sectorisation is performed by means of resin sheets used as a wall, barrier, or containment, which allow closing said sectors in a leak-tight manner, dividing the interstitial chamber based on the size of the tank with respect to the leak detection systems used. In this way, there may be cases in which the entire base of the tank and side wall can be covered with a single sector and other situations where several sectors must be established.

[0032] Where required, the continuity of the interstitial chamber can be verified by means of a specific method. For example, a valid method can be the introduction of a fluid that allows visualisation thereof in the entire interstitial chamber or detection of a possible discontinuity.

[0033] The leak detection system allows controlling the proper operation of the lining, which can emit a visible and/or audible signal when fluid enters the interstitial chamber, constituting a permanent and preventive control and protection system of the tank.

[0034] In one embodiment, the step of installing a leak detection system in each of these sectorised compartments comprises the step of perforating, by means of at least two through holes, either the side wall or the base, of the bottom section of the tank, up to the interstitial chamber of said compartment, for each of the sectorised interstitial compartments.

[0035] These holes communicate said intermediate layer with the inside or with the outside of the tank, and allow the installation of conduits that will enable the subsequent installation of the leak detection system on the interstitial chamber. As indicated, in the case where the bottom section is divided, the installation of the leak detection system is installed in each of the sections into which the tank has been divided and which coincide with the part of the wall corresponding thereto.

[0036] In one embodiment, the step of installing a leak detection system in each of the sectorised compartments comprises the step of installing a pressurisation and/or depressurisation conduit, through one of the through holes of the tank which connects the interstitial chamber, of each of these compartments, wherein said conduit is configured to introduce and/or extract fluid of said interstitial chamber with respect to the outside of the tank, and to alter the pressure of said chamber with respect to an inner cavity of the tank. This step can also comprise the installation of a manometer that allows showing the pressure of the fluid. Therefore, one of the two holes is for a pressurisation conduit of the circuit and the other for the measurement tube of the circuit.

[0037] In one embodiment, the method comprises the step of sealing a perimeter obturation area by means of a resin, with an end part of the primary wall, an end part of the three-dimensional layer, and an end part of the secondary wall being located, in said obturation area, on the inner surface of the bottom section of the tank; wherein said sealing step causes the leak-tight closure of the interstitial chamber with respect to an inner cavity of the tank.

[0038] This step follows the steps of applying the primary wall, the interstitial layer, and the secondary wall. The resin is applied in viscous state and solidifies generating a solid partition which seals the interstitial chamber. The perimeter obturation area is located at the height of between 20 and 120 cm of the side wall of the tank measured from the base of said tank, i.e., up to where the laminar lining walls are located. Preferably, the mentioned end parts of the layers and of the wall are substantially aligned, such that the sealing of the chamber is simpler.

[0039] In one embodiment, the tank is manufactured in a material selected from metal and plastic, and is configured to retain fluid products derived from petroleum. Preferably, the flexural strength of the side wall and of the base of the tank to be lined is equivalent to the flexural strength of a 1 mm-thick S-275 steel. The equivalence can be demonstrated by means of standardised testing.

[0040] In one embodiment, the method comprises the step of applying a priming layer of adherent resin on the inner surface of the buried bottom section of the tank, prior to the step of applying the primary wall, in order to rigidly fix said primary wall to the bottom section; wherein said adherent resin is preferably selected from the group consisting of polyester, epoxy, vinyl ester, and polyurethane, where other resins with similar characteristics can also be used.

[0041] In one embodiment, the three-dimensional layer, used for creating the interstitial chamber, is selected from the group consisting of:

• two flat parallel fabrics attached to one another by means of fibres of the same material;
• a foam; and
• a semi-rigid structure of constant thickness.

[0042] In one embodiment, the primary laminar wall and secondary laminar wall are applied and adhered in the form of laminar fragments or flexible tiles of larger or smaller size, as appropriate. To ensure the leak-tight closure of the interstitial chamber, these laminar fragments or tiles can be superimposed by at least 10 cm, preventing possible leaks or gaps between them, although scraps or the same laminar material can also be used to cover gaps, grooves, or slots.

[0043] In one embodiment, the primary wall and the secondary wall are manufactured in a plastic material reinforced with a material selected from: fibreglass, unsaturated polyester resin, fibreglass-reinforced epoxy resin (GRP-EP), and a combination of the foregoing. Both walls can be made of the same material, although it is not incompatible for said walls to be made of different materials, provided that said different materials are compatible.

[0044] In an embodiment, the method comprises the step of verifying the leak-tightness of the interstitial chamber, delimited between the primary laminar wall and secondary laminar wall with an electric comb. This is due to the fact that, after completing the steps of applying the lining, it is suitable to check the leak-tightness of the interstitial chamber before filling the tank for use thereof.

[0045] In addition to the method, the invention also comprises the lining for the inner surface of a bottom section of a vertical-axis, aerial, atmospheric, single-walled fluid tank, wherein said bottom section is completely or partially buried underground, wherein said lining comprises:

• a primary laminar lining wall applied on the inner surface of the buried bottom section of the tank, covering said surface completely, maintaining its structure;
• a three-dimensional layer applied on the primary wall, covering said primary wall;
• a secondary laminar lining wall applied on the three-dimensional layer, covering said layer;

wherein the three-dimensional layer is located between the primary wall and the secondary wall, comprising a hollow, and preferably monitored, interstitial chamber; and wherein the bottom section comprises a bottom base and a side wall fraction of the tank which comprises, from the base of said tank, a height of up to between 20 and 120 cm with respect to said base.

[0046] In an embodiment of the lining, the interstitial chamber is sectorised into one or more interstitial compartments; wherein each of these sectorised compartments comprises a leak detection system configured to detect leaks in each of said sectorised compartments of the interstitial chamber with the primary wall and/or the secondary wall.

[0047] To control the proper operation of the lining, this leak detection system can inform, by means of emitting a visible and/or audible signal, of the entry of fluid into the interstitial chamber, constituting a permanent and preventive control and protection system of the tank.

[0048] In an embodiment of the lining, the leak detection system comprises a pressurisation and/or depressurisation conduit inserted in a through hole of the tank, which connects with the interstitial chamber, for each of these compartments, wherein said conduit is configured to introduce and/or extract fluid of said interstitial chamber, and to alter the pressure of said chamber, with respect to an inner cavity of the tank.

[0049] In an embodiment of the lining, the leak detection system of each of the compartments comprises:

• a pressure change detector sensor configured to measure the pressure inside the interstitial chamber of each corresponding compartment;

wherein said detector sensor is connected to an alarm device indicating leaks by means of visible and/or audible signals, which is activated when the sensor detects a change in pressure.

[0050] For a correct operation of the leak detection system, the pressure of the interstitial chamber must be higher than the hydrostatic pressure of the liquid stored in the tank under maximum fill conditions.

[0051] In one embodiment, the leak detection system of each of the compartments comprises:

• a fluid system leak detector configured to measure fluid loss inside the interstitial chamber of each corresponding compartment;

wherein said detector is connected to a leak indicator device for indicating leaks by means of light and/or sound signals.

[0052] This detector allows detecting a leak in the tank using a fluid as leak detection means, introduced in the interstitial chamber, such that any leak in one of the walls of the tank is reflected as a drop in the fluid level in the detector. This fluid can be a gas, a vapour, or a liquid.

[0053] In an embodiment of the lining, the three-dimensional layer for the interstitial chamber is selected from the group consisting of:

• two flat parallel fabrics attached to one another by means of fibres of the same material;

• a foam; and
• a semi-rigid structure of constant thickness.

[0054] In an embodiment of the lining, the primary laminar lining wall is rigidly fixed on the inner surface of the buried bottom section of the tank by means of an adherent resin selected from the group consisting of polyester, epoxy, vinyl ester, and polyurethane, where other resins with similar characteristics can also be used.

[0055] In one embodiment, the lining comprises a closure seal made of resin in a perimeter obturation area located in an end part of the primary wall, of the three-dimensional layer, and of the secondary wall, located on the inner surface of the bottom section of the tank; wherein said seal causes the leak-tight closure of the interstitial chamber with respect to an inner cavity of the tank.

[0056] This seal provides a solid partition which closes the interstitial chamber in a leak-tight manner. The perimeter obturation area is located at the height of between 20 and 120 cm of the side wall of the tank measured from the base of said tank, i.e., up to where the laminar lining walls are located. Preferably, the mentioned end parts of the layers and of the wall are substantially aligned, such that the seal only occupies a narrow strip.

[0057] In one embodiment, the primary laminar wall and secondary laminar wall comprise the form of laminar fragments or flexible tiles of larger or smaller size. These tiles or laminar fragments can be superimposed by at least 10 cm, which prevents possible leaks due to gaps between them.

[0058] In one embodiment, the primary wall and the secondary wall are manufactured in a plastic material reinforced with a material selected from: fibreglass, unsaturated polyester resin, fibreglass-reinforced epoxy resin (GRP-EP), and a combination of the foregoing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] With the intention of helping to better understand the system developed and in relation to a practical and preferred exemplary embodiment thereof, a series of drawings is offered where the following has been represented:

Figure 1 shows a perspective diagram of a vertical-axis, aerial, atmospheric, single-walled fluid tank, in which the inner surface of the bottom base is covered with a primary wall applied on the internal surface, with a three-dimensional layer applied on the primary wall, and a secondary wall applied on the three-dimensional layer.

Figure 2 shows a detail of Figure 1 in which the laminar walls and the three-dimensional layer are shown stacked on the inner surface of the bottom base of the tank.

Figure 3 shows a perspective diagram of a fluid tank in which a fraction of the side wall of the tank is lined by means of the lining.

Figure 4 shows a detailed schematic view of a corner of the tank, in which the pressurisation and/or depressurisation conduit is arranged, inserted through a through hole of said tank.

Figure 5 shows a schematic view of a sectorisation of the interstitial chamber, which is divided into 4 compartments, one of said compartments being connected with a leak detection system.

[0060] A list of the references used in the figures is provided below:

(1) Tank

(2) Inner surface

(3) Primary wall

(4) Three-dimensional layer

(5) Secondary wall

(6) Closure seal

(7) Conduit

(8) Leak detection system

(9) Compartments

(10) Side wall fraction

PREFERRED EMBODIMENT OF THE INVENTION

[0061] As can be seen in the figures, particularly in Figures 1 and 3, the invention consists of a method for lining an inner surface (2) of a bottom section of a vertical-axis, aerial, atmospheric, single-walled fluid tank (1), wherein said section is completely or partially buried underground, as well as the actual lining for said type of tanks (1).

[0062] In other words, for tanks (1) that are usually manufactured in steel, configured for storing fluids derived from petroleum and having the bottom part of said tank (1) buried or partially buried, which allows ensuring or facilitating its stability and the support thereof on the ground on which it is located without having to bury them entirely or to use any support structures, thereby reducing the cost it entails.

[0063] The lining method of the invention comprises a first initial step in which cleaning of the inside of the tank (1) to be lined, as well as degassing, can be performed, allowing a user to enter the tank and apply layers of lining on the inner surface (2) of said tank. Taking advantage of said internal cleaning, cleaning of the means for opening and accessing said interior, such as a hatch, which can be affected by the internal and external wear conditions to which the tanks (1) are subjected, can also be performed.

[0064] Once cleaning and degassing of the inside of the tank (1), as well as the removal of waste that may remain after emptying the tank, have been performed, the wall of the tank (1) is repaired in those areas in which repair is required, as they have sustained wear that has generated imperfections or reductions in thickness. To that end, the thicknesses of different parts of the tank are measured and it is puttied with a corrosion-resistant material.

[0065] After the step of correcting the imperfections, a priming layer of adherent resin, which allows applying and fixing a primary wall (3) to the bottom section of the tank (1) that is buried, can be applied on the inner surface (2) of the buried bottom section of the tank (1).

[0066] It is only necessary to apply said resin and to line, with the lining, the bottom section of the tank (1), because the rest of said tank (1) is not buried, and therefore the detection and reduction of fluid leak generation is simpler and more obvious. In this way, the economic cost of performing the lining is lower than that required when a complete lining of the tank (1) is performed.

[0067] This adherent resin can be any which allows adhering the primary wall (3) to the inner surface (2) of the wall of the tank (1), ensuring said fixing when said tank (1) stores fluids derived from petroleum. Preferably, it is selected from polyester, epoxy, vinyl ester, or polyurethane resins.

[0068] To ensure that the priming layer of resin is suitable, checks can be performed with adherence specimens before performing the step of applying any laminar layer on said resin.

[0069] If the priming layer is suitable, a primary laminar lining wall (3) is applied on the resin-impregnated inner surface (2), covering said surface (2) completely, maintaining its structure.

[0070] After applying the primary wall (3), the method comprises the step of applying a three-dimensional layer (4) on the primary wall (3), covering said primary wall (3).

[0071] This three-dimensional layer (4) can consist of two flat parallel fabrics attached to one another by means of fibres of the same material, a foam, or a semi-rigid structure of constant thickness.

[0072] The application of this three-dimensional layer (4) on the primary wall (3) can be performed by fixing both parts by means of a resin, or directly by placing and supporting the three-dimensional layer (4) on the primary wall (3), since the geometry and arrangement of the tank (1) favours the accommodation of the three-dimensional layer (4) on the primary wall (3) due to the effect of gravity and pressure generated inside the tank (1).

[0073] Once the three-dimensional layer (4) has been applied on the primary wall (3), a secondary laminar lining wall (5) can be applied on the three-dimensional layer (4), covering said layer (4) entirely. Therefore, the three-dimensional layer (4) is located between the primary wall (3) and the secondary wall (5), separating them completely, comprising a hollow interstitial chamber through which a fluid such as a gas or a liquid can flow.

[0074] One of the main features of this method with respect to those indicated in the background is that the bottom section on which the lining walls (3, 5) and the three-dimensional layer (4) are applied merely comprises the bottom base and a side wall fraction (10) of the tank (1), which can comprise a height, measured from the base, of between 20 and 120 cm which is often the depth at which the tanks (1) are buried. In fact, the height of the covering must be somewhat greater than the depth at which the tank (1) is buried.

[0075] During the step of applying the three-dimensional layer (4), sectorisation of the interstitial chamber generated with the application thereof can be performed, dividing said chamber into one or more sectorised compartments (9). This sectorisation is due to the need to check for the existence of any leak in the tank (1).

[0076] In other words, to check for the existence of leaks, a leak detection system (8) which allows detecting leaks either with the primary wall (3), and therefore with the wall of the tank (1), or with the secondary wall (5), is installed in each of these sectorised compartments (9). If the interstitial chamber is not sectorised, it is possible that it is too large in size, preventing the installation of any leak detection system (8).

[0077] This step of installing a leak detection system (8) in each of these sectorised compartments (9) can also comprise the step of perforating, by means of through holes, the bottom section of the tank (1) up to the interstitial chamber of said compartment (9).

[0078] A conduit (7) which connects with the interstitial chamber of the compartment (9) in which the hole is located is installed through said hole, allowing the introduction and/or extraction of fluid, as well as the change in the pressure of said interstitial chamber with respect to the outside and inside of the tank (1).

[0079] In other words, the leak detection system (8) can work such that the interstitial chamber has a different pressure with respect to the pressure of the fluid stored in the tank (1), as well as with respect to the outside of said tank (1), such that in the event of a leak in any of the two walls (3, 5), the pressure of the interstitial chamber is altered, a manometer sensor can detect same and send a signal to a warning device which generates sound or visual signals. Moreover, the leak detection system (8) can work by having a liquid inside the interstitial chamber and a sensor that measures the loss of said fluid in said chamber, being connected to a warning device such as the one defined.

[0080] To ensure the leak-tightness of the interstitial chamber, the lining method also comprises a step of applying a closure seal (6) in a perimeter obturation area, with an end part of the primary wall (3), an end part of the three-dimensional layer (4), and an end part of the secondary wall (5) being located, in said obturation area, on the inner surface (2) of the bottom section of the tank (1) such that said sealing step generates the leak-tight closure of the interstitial chamber with respect to an inner cavity of the tank (1).

[0081] To ensure that each of the walls (3, 5) and the three-dimensional layer (4) are applied correctly, the leak-tightness of the interstitial chamber, delimited between said laminar walls (3, 5), can be verified with an electric comb. Similarly, after placing each of the walls (3, 5) by means of flexible tiles or fragments, the thickness can also be measured to ensure a minimum which allows withstanding structural loads.

[0082] Preferably, the primary wall (3) and the secondary wall (5) are manufactured in a fibreglass-reinforced plastic material as it provides suitable characteristics for the use described.

[0083] In addition to the lining method, the invention also comprises the actual lining of an inner surface of a bottom section of a vertical-axis, aerial, atmospheric, single-walled fluid tank (1), wherein said bottom section is completely or partially buried underground. A lining that can be generated from the described method.

Claims

1. A method for lining an inner surface (2) of a bottom section of a vertical-axis, aerial, atmospheric, single-walled fluid tank (1), wherein said section is completely or partially buried underground, characterised in that said method comprises the following steps:

- applying a primary laminar lining wall (3) on the inner surface (2) of the buried bottom section of the tank (1), covering said surface (2) completely, maintaining its structure;

- applying a three-dimensional layer (4) on the primary wall (3), covering said primary wall (3);

- applying a secondary laminar lining wall (5) on the three-dimensional layer (4), covering said layer (4);

wherein the three-dimensional layer (4) is located between the primary wall (3) and the secondary wall (5), separating them completely, comprising a hollow interstitial chamber; and wherein the bottom section, on which the lining walls (3, 5) and the three-dimensional layer (4) are applied, comprises a bottom base and a side wall fraction (10) of the tank (1) which comprises, from the base of said tank, a height of up to between 20 and 120 cm with respect to said base.

2. The method for lining the inside of a tank (1) according to claim 1, comprising the steps of:

- sectorising the interstitial chamber, dividing said chamber into one or more sectorised interstitial compartments (9); and

- installing in each of these sectorised compartments (9) a leak detection system (8) configured to detect leaks in each of said sectorised compartments (9) of the interstitial chamber with the primary wall (3) and/or the secondary wall (5).

3. The method for lining the inside of a tank (1) according to the preceding claim, wherein the step of installing a leak detection system (8) in each of these sectorised compartments (9) comprises the step of perforating, by means of at least two through holes, a side wall or base of the bottom section of the tank (1), up to the interstitial chamber of said compartment (9), for each of the sectorised interstitial compartments.

4. The method for lining the inside of a tank (1) according to the preceding claim, wherein the step of installing a leak detection system (8) in each of the sectorised compartments (9) comprises the step of installing a pressurisation and/or depressurisation conduit (7) through a through hole of the tank (1) which connects the interstitial chamber, of each of these compartments (8), wherein said conduit (7) is configured to introduce and/or extract fluid of said interstitial chamber with respect to the outside of the tank (1), and/or to alter the pressure of said chamber with respect to an inner cavity of the tank (1).

5. The method for lining the inside of a tank (1) according to any of the preceding claims, comprising the step of sealing, by means of a resin, a perimeter obturation area generating a closure seal (6), with an end part of the primary wall (3), an end part of the three-dimensional layer (4), and an end part of the secondary wall (5), being located, in said obturation area, on the inner surface (2) of the bottom section of the tank (1); wherein said sealing step causes the leak-tight closure of the interstitial chamber with respect to an inner cavity of the tank (1).

6. The method for lining the inside of a tank (1) according to any of the preceding claims, wherein the tank (1) is manufactured in a material selected from metal and plastic, and is configured to retain fluid products derived from petroleum.

7. The method for lining the inside of a tank (1) according to the preceding claim, wherein the flexural strength of the side wall and of the base of the tank (1) is equivalent to the flexural strength of a 1 mm-thick S-275 steel.

8. The method for lining the inside of a tank (1) according to any of the preceding claims, comprising the step of applying a priming layer of adherent resin on the inner surface (2) of the buried bottom section of the tank (1), prior to the step of applying the primary wall (3), in order to rigidly fix said primary wall (3) to the bottom section; wherein said adherent resin is preferably selected from the group consisting of polyester, epoxy, vinyl ester, and polyurethane.

9. The method for lining the inside of a tank (1) according to any of the preceding claims, wherein the three-dimensional layer (4) is selected from the group consisting of:

- two flat parallel fabrics attached to one another by means of fibres of the same material;

- a foam; and

- a semi-rigid structure of constant thickness.

10. The method for lining the inside of a tank (1) according to any of the preceding claims, wherein the primary laminar wall (3) and secondary laminar wall (5) are applied and adhered in the form of laminar fragments or flexible tiles.

11. The method for lining the inside of a tank (1) according to any of the preceding claims, wherein the primary wall (3) and the secondary wall (5) are manufactured in a plastic material reinforced with a material selected from: fibreglass, unsaturated polyester resin, fibreglass-reinforced epoxy resin (GRP-EP), and a combination of the foregoing.

12. The method for lining the inside of a tank (1) according to the preceding claim, comprising a step of verifying the leak-tightness of the interstitial chamber, delimited between the primary laminar wall (3) and secondary laminar wall (5) with the electric comb.

13. A lining for the inner surface of a bottom section of a vertical-axis, aerial, atmospheric, single-walled fluid tank (1), wherein said bottom section is completely or partially buried underground, characterised in that said lining comprises:

- a primary laminar lining wall (3) applied on the inner surface (2) of the buried bottom section of the tank (1), covering said surface (2) completely, maintaining its structure;

- a three-dimensional layer (4) applied on the primary wall (3), covering said primary wall (3);

- a secondary laminar lining wall (5) applied on the three-dimensional layer (4), covering said layer;

wherein the three-dimensional layer (4) is located between the primary wall (3) and the secondary wall (4), comprising a hollow interstitial chamber; and wherein the bottom section comprises a bottom base and a side wall fraction (10) of the tank (1) which comprises, from the base of said tank (1), a height of up to between 20 and 120 cm with respect to said base.

14. The lining for the inner surface of a bottom section of a fluid tank (1) according to the preceding claim, wherein the interstitial chamber is sectorised into one or more interstitial compartments (9); and wherein each of these sectorised compartments (9) comprises a leak detection system (8) configured to detect leaks in each of said sectorised compartments (9) of the interstitial chamber with the primary wall (3) and/or the secondary wall (5).

15. The lining for the inner surface of a bottom section of a fluid tank (1) according to the preceding claim, wherein the leak detection system (8) comprises a pressurisation and/or depressurisation conduit (7) inserted in a through hole of the tank (1) which connects with the interstitial chamber, for each of these compartments (9), wherein said conduit (7) is configured to introduce and/or extract fluid of said interstitial chamber, and to alter the pressure of said chamber, with respect to an inner cavity of the tank (1).

16. The lining for the inner surface of a bottom section of a fluid tank (1) to any of claims 14 to 15, wherein the leak detection system (8) of each of the compartments comprises:

- a pressure change detector sensor configured to measure the pressure inside the interstitial chamber of each corresponding compartment (9);

wherein said detector sensor is connected to an alarm device indicating leaks by means of light and/or sound signals.

17. The lining for the inner surface of a bottom section of a fluid tank (1) to any of claims 14 to 15, wherein the leak detection system (8) of each of the compartments (9) comprises:

- a fluid system leak detector configured to measure fluid loss inside the interstitial chamber of each corresponding compartment (9);

wherein said detector is connected to a leak indicator device configured to indicate a leak by means of light and/or sound signals.

18. The lining for the inner surface of a bottom section of a fluid tank (1) to any of claims 13 to 17, wherein the three-dimensional layer (4) is selected from the group consisting of:

- two flat parallel fabrics attached to one another by means of fibres of the same material;

- a foam; and

- a semi-rigid structure of constant thickness, having a regular or irregular shape.

19. The lining for the inner surface of a bottom section of a fluid tank (1) according to any of claims 13 to 18, wherein the primary laminar lining wall (3) is rigidly fixed on the inner surface (2) of the buried bottom section of the tank (1) by means of an adherent resin selected from the group consisting of polyester, epoxy, vinyl ester, and polyurethane.

20. The lining for the inner surface of a bottom section of a fluid tank (1) according to any of claims 13 to 19, comprising a closure seal (6) made of resin in a perimeter obturation area located in an end part of the primary wall (3), of the three-dimensional layer (4), and of the secondary wall (5), located on the inner surface of the bottom section of the tank (1); wherein said seal causes the leak-tight closure of the interstitial chamber with respect to an inner cavity of the tank (1).

21. The lining for the inner surface of a bottom section of a fluid tank (1) according to any of claims 13 to 20, wherein the primary laminar wall (3) and secondary laminar wall (5) comprise the form of laminar fragments or flexible tiles.

22. The lining for the inner surface of a bottom section of a fluid tank (1) according to any of claims 13 to 21, wherein the primary wall (3) and the secondary wall (5) are manufactured in a plastic material reinforced with a material selected from: fibreglass, unsaturated polyester resin, fibreglass-reinforced epoxy resin (GRP-EP), and a combination of the foregoing.

Drawing