This application claims the benefit of priority of U.S. Provisional Patent Application No.

62/397,448, filed on September 21 , 2016, which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a chemical delivery system for mitigating soil-side corrosion of metal structures in contact with soil. The chemicals in the delivery system may, for example, include a volatile corrosion inhibitor and/or a biocide, and may include mixtures of multiple compounds. The chemicals in the delivery system may be in various forms, such as solutions and slurries. The invention is especially well suited for mitigating soil-side corrosion on aboveground storage tank bottoms of any size, as a stand-alone system or in conjunction with cathodic protection systems.

BACKGROUND OF THE INVENTION Soil-side corrosion on single and double bottom tanks is a principal cause of storage tank failure and imposes a major environmental and operational challenge worldwide. Several techniques have been adopted to mitigate soil-side corrosion of Aboveground Storage Tank (AST) floors, such as bituminous sand, impressed current cathodic protection, and coatings. However, the total effectiveness of these techniques, as standalone techniques or combined, has been questionable in providing the required protection. Practical experience has shown that the bituminous layer may trap moisture and corrosive species between the underside of the tank floor and the construction pad, creating a corrosive environment. When the bituminous layer is combined with cathodic protection (CP) to shield cathodic current, this corrosive environment may render the CP system at least partially ineffective. It has also been concluded that inevitable air gaps between construction pads and tank bottom plates block CP current at that location and consequently prevent its uniform distribution on the underside surface of the tank bottom.

Inspection activities during the service life of the tank have shown that underside coating of bottom plates alone cannot prevent corrosion, due to unavoidable defects during its application and deterioration during tank operation.

There is a growing industrial awareness about the importance of finding a viable solution to supplement the performance of the aforementioned techniques in an attempt to achieve a comprehensive corrosion protection scheme to the tank bottom. One solution is the introduction of chemicals (e.g., volatile corrosion inhibitors and biocides) into the under tank environment to treat the environment (e.g., sand pad) under the tank, allowing volatile corrosion inhibitor molecules to diffuse through the sand to the tank bottoms plates and eliminating the biological corrosive species to eventually mitigate soil-side corrosion on storage tank bottoms. The volatile corrosion inhibitor is a chemical substance that acts to reduce soil-side corrosion by a combination of volatilization from a volatile corrosion inhibitor material, vapor transport in the headspace between floor plates and the tank pad atmosphere, and condensation onto surfaces in the space. The condensation process includes adsorption, dissolution, and hydrophobic effects on metal surfaces, where the rate of soil-side corrosion of bottom plates' surfaces is thereby inhibited.

SUMMARY OF THE INVENTION

The present invention provides a means to ensure effective online delivery of any chemicals required to treat the environment under metal structures in contact with the soil, such as storage tanks. The system of the present invention provides protection for storage tanks against soil-side corrosion, without putting the storage tanks out of service. Implementation of this system provides protection to bottom plates at air gaps, areas where soil is dry and at areas where coating has failed, and provides protection in cases of high corrosivity due to ingress or entrapment of moisture under the tank.

The present invention is directed to a chemical delivery system for mitigating soil-side corrosion of metal structures in contact with soil, such as storage tanks. The chemicals in the delivery system may, for example, include a volatile corrosion inhibitor and/or a biocide, and may include mixtures of multiple compounds. The chemicals in the delivery system may be in various forms, such as solutions and slurries. The invention is especially well suited for mitigating soil-side corrosion on aboveground storage tank bottoms of any size, as a stand-alone system or in conjunction with cathodic protection systems. It is designed to ensure effective distribution of the chemicals into the under tank environment. The effective distribution of chemicals may consist of a relatively uniform distribution of chemicals, but in some applications and embodiments, a relatively uniform distribution of chemicals is not necessary for effective corrosion protection. Depending on the circumstances, it may be desirable to effect a variable distribution of chemicals and/or distribution to certain predetermined locations. For example, treating sections of a large area at a time may be desirable in some circumstances, in order to decrease the amount of chemicals used or decrease the rate of application. The effective distribution of chemicals can be accomplished, for example, through a network of concentric dispensing rings with built-in pressure and flow self-regulating orifices connected to control valves connected to a data acquisition and control system, operated by a custom-made application software. The control system is designed to ensure the delivery of a pre-calculated volume of chemical per dispensing ring. The dispensing rings are designed to withstand all the dead load and hydrostatic forces imposed by the tank itself and the stored fluid without affecting the integrity of the dispensing ring or the intended flow rate of the chemicals throughout the life of the tank. The system is also designed with a provision for intrinsic safety for hazardous locations. For large tanks (e.g., 130 meters in diameter), it is designed with a provision to pump the chemical through the flow check lines, in addition to the inlet lines, to ensure timely and uniform delivery. In one embodiment, the present invention is a chemical delivery system including a conduit, and an inlet line extending from a first end of the conduit. As used herein, a "conduit" may be any carrier of fluids, such as one or more sections of tubing or pipe. The conduit includes a plurality of orifices in the wall of the conduit, and a passageway within the conduit. The passageway is adapted to direct a fluid from within the conduit to at least one orifice of the plurality of orifices. More than one such passageway may be included in the conduit. The chemical delivery system may also include a check line, or flow check line, extending from a second end of the conduit. The chemical delivery system may further include a junction box connected to the inlet line and to the check line; a chemical dispensing skid comprising a pump, wherein the chemical dispensing skid is connected to the junction box by an inlet hose assembly and a flow check hose assembly; and a supply tank for holding the fluid (i.e. the chemical delivered through the system of the present invention), wherein the supply tank is connected to the chemical dispensing skid by a line or another connector.

In another embodiment, the present invention is a chemical delivery system including a conduit configured into a plurality of sections. Each section of the conduit includes a plurality of orifices in the wall of the conduit, and a passageway within the conduit. The passageway is adapted to direct a fluid from within the conduit to at least one orifice of the plurality of orifices. More than one such passageway may be included in the conduit. This embodiment also includes a plurality of inlet lines, wherein each inlet line extends from a first end of a different section of the conduit. The chemical delivery system may also include a plurality of check lines, or flow check lines, each extending from a second end of a section of the conduit, and each check line extending from a different section of the conduit. The chemical delivery system may further include a junction box including an inlet bracket and a check line bracket, wherein the inlet lines are attached to the inlet bracket and the check lines are attached to the check line bracket; a chemical dispensing skid comprising a pump, wherein the chemical dispensing skid is connected to the junction box by an inlet hose assembly and a flow check hose assembly; and a supply tank for holding the fluid (i.e. the chemical delivered through the system of the present invention), wherein the supply tank is connected to the chemical dispensing skid by a line or another connector.

Chemical dispensing skids of embodiments of the present invention, including the embodiments discussed above, may be manually operated or computer-operated. In some embodiments, the system is adapted to allow both manual operation and computer operation of the chemical dispensing skid. The chemical dispensing skid, when operated by computer, may be operated through the use of a software application. The software application may be adapted to allow parameters of the chemical delivery system to be monitored remotely and/or controlled remotely. For example, parameters may be monitored remotely through the use of a telecommunication network, a Subscriber Identity Module (SIM) card, an information transfer protocol, or a combination thereof.

The conduit of may be configured into various shapes, such as one or more independent rings, one or more interconnected rings, one or more spiral rings, or one or more substantially straight lines. If the conduit includes interconnected rings, the rings may be connected by a section of conduit. This section of conduit may, for example, have the appearance of a radial line passing through the rings. In some embodiments, the conduit may be configured into substantially concentric rings, or into substantially parallel lines. The conduit may be surrounded by a ringwall, in which case the inlet line or lines may pass through an aperture in the ringwall. The conduit may be embedded in the ground or in a storage tank foundation.

The present invention can be used with any structure with a corrodible surface, including but not limited to tanks, bins, silos, sheds, railroad cars, and semi-trailers when not elevated on wheels. The invention is particularly useful when incorporated into a single bottom aboveground storage tank foundation. For example, the invention can be incorporated into the storage tank foundation during the construction of a new tank, or it can be incorporated into the foundation of an existing tank at the time of complete bottom replacement. The invention is also designed to be effective when installed during installation of double bottoms. The system is applicable to all types of tank foundations, including tank pads such as, but not limited to, compacted sand, bituminous sand, and asphalt pads with trenches cut into the existing tank pad.

It is an object of the present invention to provide a chemical dispensing system to deliver any chemicals required to treat the environment under metal structures in contact with soil, such as storage tanks, thereby providing protection against soil-side corrosion. In some embodiments, instead of using the system to protect metal structures in contact with soil, the system may be used to protect metal structures (or other corrodible structures) which are in contact with non-soil materials that are in or on the ground. It may also be used to protect corrodible structures directly in contact with a body of water or with electrolytes. In some embodiments, instead of or in addition to using the system of the invention to protect the base or bottom of a metal structure from soil-side corrosion, the invention may be used protect a side or top surface of a metal structure, especially if the side or top surface is in contact with another surface.

Advantages of implementation of the present invention include: extension of the service life of tank bottoms, reduction of costs associated with maintenance and repair during the service life of tanks, and an increase in the span between inspection intervals. The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the

accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a first embodiment of a tubing configuration of the present invention.

FIG. 2 is a perspective view of a portion of the embodiment of FIG. 1 and of a junction box of the present invention.

FIG. 3 is a side view of the junction box of FIG. 2. FIG. 4 is a perspective view of an embodiment of components in the junction box of FIG. 2.

FIG. 5 is a perspective view of an embodiment of a hose assembly connecting a junction box to a pump unit.

FIG. 6 is a perspective view of an embodiment of an inlet hose assembly and a flow check hose assembly connecting one ring within the junction box to a chemical dispensing skid. FIG. 7 shows a fluid schematic of an embodiment of the system of the present invention. FIG. 8 shows an alternative fluid schematic of the system of the present invention.

FIG. 9 is a partial perspective view of a possible configuration of the embodiment shown in FIG. 1.

FIG. 10 is a cutaway perspective view of a section of the tubing of FIG. 9, showing one possible configuration of an orifice in the tubing.

FIG. 11 A is a diagram of a second embodiment of the tubing configuration of the present invention.

FIG. 1 IB is a diagram of a third embodiment of the tubing configuration of the present invention.

Fig 11 C is a diagram of a fourth embodiment of the tubing configuration of the present invention.

Fig 12 shows a software application user interface for the control of a chemical dispensing skid. DETAILED DESCRIPTION OF THE INVENTION

The objects, features, and advances represented by the present invention will now be presented in terms of detailed embodiments. Other embodiments and aspects of the invention are recognized as being within the grasp of those having ordinary skill in the art.

The present invention is directed to a chemical delivery system for mitigating soil-side corrosion of metal structures in contact with soil. The chemicals in the delivery system may, for example, include a volatile corrosion inhibitor and/or a biocide, and may include mixtures of multiple compounds. The delivery system may also include a single chemical or compound.

In one embodiment, the system is an automated modular chemical dispensing system to mitigate soil-side corrosion on above ground storage tank bottoms, by treating and conditioning the environment under the tank bottom plates. It is designed to uniformly introduce liquid chemicals (e.g., volatile corrosion inhibitors, biocides, pH adjusting solutions) into the interstitial space between the tank floor and the construction pad with the objective to condition the environment under the tank, allow volatile corrosion inhibitor molecules to diffuse through the sand to the tank bottoms plates, and eliminate the biological corrosive species to eventually mitigate soil- side corrosion on storage tank bottoms. The dispensing system consists of two subsystems: a permanent system or package to be installed under the tank bottom plates (e.g., during construction of new tanks or complete re-bottoming of existing tanks), and an application system or package for injection of chemicals under the tank.

Permanent System

The main components of the permanent system are flexible tubing and a junction box. They are installed permanently under tank bottom plates (e.g., during construction of new tanks or complete re-bottoming of existing tanks).

FIG. 1 is a diagram of an embodiment of the tubing configuration of the present invention, illustrating a typical layout of tubing 1 underneath a storage tank. This embodiment can be described as an independent concentric rings design, since the tubing 1 forms a plurality of concentric rings which have the same center point. The rings can be operated independently from each other; in other words, as shown in FIG. 1 , the rings may be disconnected from each other with no interconnecting tubing. Each ring of tubing 1 has a separate inlet line 2 and a check line 3 as shown for the outermost ring.

In the embodiment of FIGS. 1, the rings defined by tubing 1 are at a substantially equal distance from each other. However, in other embodiments, distances between different rings may vary. Moreover, the distance between any two rings may vary such that, for example, the distance between two rings at a point near inlet lines 2 is different from the distance between the same two rings at a point opposite to the inlet lines 2. The spacing between the rings is preferably between 0.5 meter and 3 meter. However, in other embodiments, the spacing may be less than 0.5 m or greater than 3 m. Surrounded by the rings is the ringwall 4, which may be made of concrete. Each ring is connected to its own inlet line 2 and flow check line 3. As shown in FIG. 2, all inlet lines 2 and check lines 3 from each ring then lead outward through the ringwall 4. FIG. 2 illustrates the connection between the concentric ring tubing 1. The inlet lines 2 and check lines 3 are bundled through a large pipe 5, which leads outward through the ringwall 4 and then leads all connections to a junction box 6.

As shown in FIG. 3, the junction box 6 encloses all inlet lines 2 and all check lines 3 which are connected to a pipe assembly 7. All inlet lines are then attached to an inlet bracket 8. All check lines are attached to a check line bracket 9. Specifically, all inlet and flow check lines 2,3 are gathered and fitted through the ringwall 4 through the pipe 5 which may be installed during casting of the ringwall. The pipe 5 containing all inlet and flow check lines 2, 3 is then connected to a junction box 6 in which all inlet and flow check lines are grouped into two separate manifolds. FIG. 3 shows the inlet bracket 8 and the check line bracket, or flow check bracket, 9. In the embodiments shown in the figures, each bracket 8,9 may have as many as 6 respective lines attached to them. However, if the brackets 8,9 are required to accommodate more or fewer lines, the design can be scaled up or down to accommodate as many lines as required. From a practicality and cost saving point of view, a 6-ring-system can be defined as a standard junction box. If more than 6 rings are to be installed, multiple junction boxes can be placed side by side and/or back to back.

FIG. 4 shows an inlet line 2 which passes through a hose clamp 10, fittings 1 1 , 13, 14 and elbows 12. The assembly is then attached by means of at least one U-clamp 15 to bracket 8. At the end a union 16 is fitted. Specifically, the inlet line 2 is connected through a hose clamp 10 to nipple fitting 1 1 , and then through elbows 12 and straight section fittings 13 and 14 through a U- clamp 15 to the female end of a union 16. An alternative design, but more expensive approach, has additional manual or solenoid valves installed before the union for each inlet and check line. Although FIG. 4 shows an inlet line 2, the connections shown in FIG. 4 are typical connections used to connect both inlet lines 2 and check lines 3 to the junction box 6. Further components of the chemical dispensing system of the present invention are shown in FIGS. 5-8, which are discussed below in the description of the application system.

In the embodiment shown in FIG. 1 , the rings of tubing 1 are embedded in the soil and/or in non- soil material which will be under the tank floor, in equally or variably spaced independent and separate concentric rings. The rings may, for example, be embedded in soil 30 to 50 cm below ground level, but in some embodiments, the tubing may be placed at a different distance below or above ground level. Alternatively, the rings of tubing 1 may be installed in trenches cut into foundations such as concrete or asphalt pads.

FIG. 9 shows a possible configuration of the embodiment shown in FIG. 1. In this embodiment, the plurality of concentric rings formed by the tubing 1 are held in place with respect to each other through the use of spacers 39, which are placed between the rings. The spacers may include one or more built in clips 40, which are spaced as required, defining the distance between the concentric rings. Each clip 40 may be in the shape of a clamp. The tubing 1 can easily snap into the clips 40, as the spacers 39 are designed such that they can tolerate a certain amount of deflection and then return to their original position. The clips 40 are preferably positioned every 0.5 m along the tubing 1 , allowing for an easy installation procedure, especially with regard to systems over 50 meters in diameter. In other embodiments, the clips 40 may be positioned so they are separated by distances less than or greater than 0.5 m. The spacers 39 are preferably made of plastic, and the clips 40 are designed such that the two ends of each clip 40 easily deflect and snap over the diameter of the tubing 1. In the embodiment of FIG. 9, the rings of tubing 1 have built-in flow regulating orifices which are distributed evenly along the tubing. These orifices 41 are small holes in the walls of the tubing 1. The orifices 41 used in the tubing 1 are positioned preferably every 10 to 200 cm but more preferably every 30 cm or 60 cm along the tubing. The orifices 41 may also be spaced less than 10 cm apart or more than 200 cm apart in some embodiments. As a direct result of these types of orifices 41 , uniform distribution of the chemical or chemicals is easily assured to a length of at least 200 meters along a single segment of tubing 1. These orifices or flow regulating emitters 41 are referenced in U.S. Patent No.9, 307,705 B2, which describes the use of these features with filtered water for agricultural purposes. The present invention incorporates these orifices specifically for use with chemicals, such as corrosion inhibitors, biocides, pH adjusting solution, etc., and specifically with a tubing system that is installed under tank floors. The pressure within the tubing system may be controlled manually. Alternatively, the pressure within the tubing system may be controlled through an automatic program, such as an automatic program which has an integrated pressure feedback control system. The pressure within the tubing system is preferably within the range of 4 to 10 psi. If above this range, the orifice component may become damaged, and if below this range, the uniform distribution of the chemical along the tubing may be adversely effected. However, in some embodiments, pressure within the tubing system outside of the range of 4 to 10 psi may be used, such as in applications where uniform distribution of the chemical is not required for effective corrosion control.

FIG. 10 shows, in detail, the design of a typical orifice 41. Behind the orifice or hole 41 is a tortuous path or passageway 42 within the tubing 1 which results in a pressure reduction, hence allowing for a uniform flow across a much longer length of tubing. The chemicals enter through the inside of the tubing 1 and reach the orifice 41 after passing through the tortuous passageway 42. Without these tortuous passageways 42, the first few orifices 41 would dispense the majority of the chemical and uniformity would not be assured. Application System

The main components of the application system include two hose assemblies 22, 23 and a chemical dispensing skid 35. In the embodiment shown in FIG. 6, an inlet hose assembly 22 and a flow check hose assembly 23 connect one ring within the junction box 6 to a chemical dispensing skid 35, which may be a chemical dispensing and control skid. The chemical dispensing skid can be a mobile temporary component or a longer term part of the system. As shown in FIG. 5, the hose assembly includes two valves 18 and 20, to help minimize any spillage during disassembly and reassembly, and a flexible hose 19. Unions 17 and 21 are at the ends of hose 19, providing a convenient means of making a pressurized connection. At the time of dispensing of the chemical, each hose 19, as shown in FIGS. 5 and 6, is attached from the junction box 6 to the chemical dispensing skid 35. One hose functions as part of the inlet hose assembly 22, and the second hose functions as part of the flow check hose assembly 23. One end of a hose 19 is connected to the female union 17 of the inlet line 2 of one ring on the inlet bracket 8, and the second hose 19 is connected to the female union 17 of the flow check line 3 of the same ring on the check line bracket 9 within the junction box 6, as shown in FIGS. 3, 5, and 6. By using two hoses 19, any trapped debris and or air in the lines can be flushed out through the chemical dispensing skid 35 confirming dispensing rings are functioning properly and have no leaks. This is of significant importance, because the only other alternative would be to release any trapped debris through the orifices 41, which can lead to clogging of the orifices and hence reduce the functionality of the system. Also, by having each dispensing ring connected separately to the junction box 6, a maximum level of reliability is achieved due to the absence of any junctions and any resulting potential failure points. In addition, by having multiple independent rings, additional redundancy is achieved, allowing the operator and/or the control system to skip over a ring that has failed the initial purging / flow check test and simply deliver more chemicals through the adjacent rings. For these reasons, the useful lifespan of the system is maximized.

FIGS. 7 and 8 are fluid schematics of embodiments of the system of the present invention. As shown in FIG. 7, fluid enters the system through supply drums or tanks 24. It is pumped through pump 26 to temperature sensor and transmitter 27, pressure sensor and transmitter 28, a flowmeter 29, and a pressure relieve valve 30. A filter 31 ensures trapping of any larger particulates. The line then splits off into two sections, one leading to the inlet valve 32 and the second to the flow check valve 33. All inlet lines 2, which are attached to the inlet bracket 8 are then connected to the exit side of the inlet valve 32 one at a time. The inlet line then feeds the ring and returns through the flow check line 3 to the flow check line bracket 9. It then splits at a junction into the flow check valve 33 and to the purging valve 34 and then into the purging drum 25.

In the alternative fluid schematic of FIG. 8, fluid enters the system through supply drums or tanks 24. It is pumped through a chemical dispensing skid 35 to a filter unit 31. The line then splits off into two sections. One section leads to the inlet bracket 8 which then splits off to each of the inlet lines 2, each through its own valve 36. The second section leads to the flow check bypass line 38. All flow check lines 3, which are attached to the check line bracket 9, are then connected to a valve 37, one for each ring. The flow check lines 3 then merge with the flow check bypass line 38 and to the purging valve 34, and then into the purging drum 25.

As shown in FIGS. 7 and 8, the inlet manifold or bracket 8 and check line manifold or bracket 9 are connected to the chemical dispensing skid 35. Within the dispensing skid 35, two valves (manual or automatic) control flow to the rings: the inlet valve 32 and the flow check valve 33. In addition, as shown in FIG. 7, the dispensing skid 35 incorporates a filter 31, pressure relieve valve 30, flowmeter 29, pressure sensor and transmitter 28, temperature sensor and transmitter 27, and pump 26. The pump 26 is connected to a supply tank 24 of the chemical that needs to be dispensed.

The dispensing skid 35 can either be operated manually with valves, or may be operated completely automatically using a custom designed software application (see FIG. 12). The application may allow for charting and data logging of all measured parameters, such as temperature of chemical, pressure inside tubing, flow rate, amount and type of chemical dispensed per ring, and total chemical dispensed. The application may also control the flow of the pump, allow for an automated startup and shutdown procedure, report all pertinent data through electronic reports, and/or provide connectivity over mobile phone networks to servers allowing troubleshooting, maintenance and archiving tasks. The application may allow measured parameters to be monitored remotely. For example, parameters may be monitored remotely through the use of a telecommunication network, a Subscriber Identity Module (SIM) card, an information transfer protocol, or a combination thereof.

Purging valve 34 is activated in the beginning during the purging cycle. Any excess chemical will be collected in the purging barrel or drum 25.

An alternative design for the junction box 6 can be made fully automatic by installing a solenoid valve on each inlet line and check line in the junction box 6 where each solenoid valve will be connected to a flexible hose 19 simultaneously. In this alternative design, the closing and opening of each valve may be controlled though a custom designed software application (see FIG. 12). However, this makes for a more automated system at the expense of cost, as one automated valve must be added to the permanent system. Especially when installations are in an explosion proof environment, this valve and the required electrical wiring may add significant cost to the system. Also, an automated system creates one more potential failure mode, as it must function for the duration of the system which can be over decades. This long-term use usually requires the highest grade of components, which again, would add even more cost. Hence, a sound compromise is not to have any valves as a part of the permanent system, and simply move the two hoses from the inlet line and the check line of one ring to the next pair of lines of the next ring. This does add an extra manual step by an operator, but overall should have marginal impact on the required dispensing time. The custom designed software application may also be adapted for use with other liquid dispensing devices, including other dispensers of corrosion inhibitors and/or biocides.

The system of the present invention is designed to be incorporated into a single bottom above ground storage tank foundation during new tank construction, or when an existing tank is going through a complete bottom replacement. It is also designed to be installed during installation of double bottoms. The system is applicable to all types of tank construction pads such as, but not limited to, compacted sand, bituminous sand, and asphalt pads where trenches are cut into the existing tank construction pad, and allows for an easy introduction and future replenishment without interruption of tank operations. In comparison to systems that are composed of perforated pipe ring installed either at the periphery of the tank or perforated pipe sections inserted to a limited distance through the concrete ring wall 4, the proposed modular concentric dispensing rings design ensures maximum reach and coverage of injected chemicals under the tank regardless of its size. Unlike the use of straight perforated pipe sections pushed through the tank concrete ring wall or installed previously during the construction of the tank, the presence of the orifices 41 used in the tubing 1 , as shown in FIG. 9, allows the system to achieve a uniform flow rate and hence the distribution of equal quantities of the chemicals over large distances, including distances of more than 200 meters.

An alternative design of the tubing configuration of the present invention is shown in FIG. 11 A. This embodiment can be described as a dependent concentric rings design. In this design, the concentric rings formed by the tubing 43 are interconnected to each other through tubing 44 which forms radial lines. Chemicals enter the system through inlet line 45, then travel to the center of the rings. From there the chemicals then distribute through at least two or three connecting lines of tubing 44 to each ring. Each ring has its own exit valve 46 leading to the exit line 47. Valves 46, one for each ring, allow for controlled delivery of chemicals to the rings. The flow may exit through exit line 47 if required. The main disadvantage of this design is that should there be a leak in any part of the tubing, the entire system may become ineffective and unpredictable. Any failure of any section of any tubing 43 or 44 may render the entire system ineffective in delivering the desired flow. In addition, the main weaknesses are the center distribution points with multiple joints which need to be molded and/or glued, adding to more potential sources of failures. In the embodiment shown in FIG. 1 1 A, the rings formed by tubing 43 may be at a substantially equal distance from each other. Alternatively, distances between different rings may vary.

Moreover, in some embodiments, the distance between any two rings may vary such that, for example, the distance between two rings at a point near inlet line 45 is different from the distance between the same two rings at a point opposite to the inlet line 45.

FIG. 1 IB shows yet another alternative design of the tubing configuration of the present invention. This embodiment can be described as a spiral ring design. In this design, chemicals flow in through a single inlet line 48 to the innermost ring position. From the innermost ring, the tubing 50 spirals out such that the distance between the center of the ring and the tubing 50 increases. Once the tubing 50 reaches the outer wall 4, it then bends and exists through the wall. Although quite elegant and simple, the major drawback of this design is that the single section length of the dispensing ring may easily reach a length of at least 200 meters for a tank of as small as 30 meters in diameter. As a result, it may be difficult to achieve a desired chemical distribution for tanks greater than 30 meters in diameter when using the spiral ring design. In contrast, the independent ring design of FIG. 1 can easily be scaled up to reach 100 meter in diameter, since chemicals can be pumped in first from the inlet line 2 and then from the flow check lines 3. Another potential drawback of the design of FIG. 1 IB is that, if there is any failure along any section of this design, the entire system may be rendered unusable. Any failure of any section of tubing may render the entire system ineffective in delivering the desired flow. In the embodiment shown in FIG. 1 IB, the rings (or circular sections of the spiral) defined by tubing 50 are a substantially equal distance from each other. However, in other embodiments, the distances between different rings may vary. Moreover, the distance between any two rings may vary such that, for example, the distance between two rings at a point near inlet line 48 is different from the distance between the same two rings at a point opposite to the inlet line 48. FIG. l lC shows another alternative design of the tubing configuration of the present invention. This embodiment can be described as a parallel lines design. In this design, the tubing 51 is configured to form parallel lines separated by bends in the tubing. A single inlet line 49 is used to deliver the chemicals to tubing 51 and therefore across the entire circular area within the ring wall 4. However, the weaknesses of the parallel lines design are identical to those of the spiral ring design. Specifically, any failure of any section of tubing may render the entire system ineffective in delivering the desired flow, and there are difficulties associated with scaling up the design.

In the embodiment shown in FIG. 11C, the parallel lines may be arranged at substantially the same distance from each other, or the distances between the lines may vary. In alternative embodiments, instead of forming parallel lines, the tubing 51 may form lines in which the distance between two lines varies.

Corrosion protection can be accomplished by application of a wide range of products which may be used in the chemical dispensing system of the present invention. Some corrosion is induced by specific microbial growth or formation of microbial films on a metal surface. In this situation, application of biocides may be sufficient to prevent corrosion. Most metals are more susceptible to corrosion over a specific range of pH. For many metals, an acidic pH (pH less than 7) will accelerate the corrosion process, while a higher pH may slow or prevent corrosion. In these cases, application of a pH altering chemical may be sufficient to prevent corrosion. Chemical corrosion inhibitors are widely known in the art and are readily commercially available. These are highly effective when used with the present invention. Corrosion inhibitors that function as volatile or vapor phase corrosion inhibitors are particularly well suited for use in the present invention. Non-limiting examples of volatile corrosion inhibitors which have been found highly effective for use in connection with the present invention are amine salts of nitrates, amine salts of nitrites, amine salts of organic acids, ammonium benzoate, alkali nitrites, alkali molybdates, tall oil imidazolines, and triazole compounds. Other specific examples of corrosion inhibitor ingredients useful in this invention are described in US Patent Nos. US4,275,835; US7,118,615; US5,894,040; US5,855,975; US6,054,512; US6,555,600; and US6,028,160. The above vapor phase corrosion inhibitors are available in many products sold by Cortec Corporation of St. Paul, Minnesota, under the trademark VpCI®.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.