Related Applications

[0000] The present application claims the benefit of priority to U.S.

Provisional Patent Application No. 61/986,288, filed April 30, 2014, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

[0001] The present disclosure relates to components suitable for underground use, such as drill pipes for drilling wells for oil and gas recovery and methods of making such components.

Background

[0002] Components for underground use face challenging environments such as high pressure, chemical corrosion and physical erosion. These components are very useful or even necessary in applications such as oil and gas recovery, construction of tunnels, and construction of foundation for above-grade structures.

[0003] For example, drilling wells for oil and gas recovery may involve the use of drill pipes which are connected to one another in a drill string and equipped with a drilling bit at the end. The drill string provides torque, force, and circulating fluid to the drilling bit in order to cut through various types of underground formations. Fig. 1 schematically shows a portion of an exemplary drill string, including drill pipes 1 of about 30 to 45 feet each in length and are connectable to one another by tool joints 2 at the ends of the drill pipes 1. Fig. 1 shows the drill pipes before they were connected to one another. These tool joints may be protected against wear by abrasion resistant overlays 3 and may have a diameter significantly larger than the body of the drill pipes 1. Under conditions of vertical drilling, the tool joints 2 may protect the body of the drill pipes 1 due to the larger diameter of the tool joints 2, which effectively avoid direct contact of the body of the drill pipes 1 to the wall of the well being drilled by the drill string.

[0004] If the well is not an entirely straight, such as in horizontal drilling, the drill string or individual drill pipes in the drill string may be elastically bent. The bending of the drill string or individual drill pipes, the use of increased drill pipe lengths (e.g., about 45 feet) or pipe diameters closer to but smaller than the tool joint diameter, may reduce the effectiveness of protection of the tool joints to the body of the drill pipes and may cause direct contact of the body of the drill pipes with walls of the well. Such direct contact may expose the drill pipes to wear mechanisms that may significantly affect the integrity of the drill pipes. Such mechanisms may include abrasion from contact with the underground formations, abrasion and/or galling between metal parts, and abrasion from contact with drilling fluids and drill cuttings.

[0005] Possible approaches to protect the drill pipes may include placing one or more clamps on the body of the drill pipe to keep the drill pipe away from the wall of the well, placing clamping rubber sleeves on the drill pipe, applying paints, epoxy coatings, powder metallurgical resist oxidation, welding or fusion processes either through hardsurfacing or by transfer plasma arc for a particular material alloyed to the base material of the drill pipe, and thermal spraying a wear resistant layer with a crystalline steel matrix microstructure containing precipitates of chromium carbides and borides.

[0006] These approaches may not be sufficient to eliminate the direct contact of the drill pipes to the wall of the well, or to prevent abrasion of the drill pipe from such contact. These approaches may introduce additional risks, including catastrophic failure of the drill pipe such as separation of clamps from the drill pipe downhole, undesirable metallurgical changes in the base material of the drill pipe caused by welding or fusion processes such as weakening due to the heat effect on the drill pipe itself and/or weakening of the corrosion resistant layer on the inside surface of the drill pipe, and delamination of thermal-sprayed crystalline coatings under the stress caused by large numbers of rotation of the drill pipe.

Summary

[0007] Disclosed herein is a method comprising: spraying a coating onto a surface of a component, wherein the coating is at least partially amorphous, wherein the coating is configured to protect the component for underground use.

[0008] According to an embodiment, the coating is not metallurgically bonded to the surface.

[0009] According to an embodiment, the coating is fully amorphous.

[0010] According to an embodiment, the component is a drill pipe, workstring tubing, or a production pipe.

[0011] According to an embodiment, the coating has an elastic strain limit greater than 0.103%.

[0012] According to an embodiment, the coating has an elastic strain limit greater than a yield strain of the component.

[0013] According to an embodiment, the coating has a modulus of elasticity lower than a modulus of elasticity of the component.

[0014] According to an embodiment, the coating has a modulus of elasticity of at most 150 GPa.

[0015] According to an embodiment, the coating has a hardness higher than a hardness of the surface. [0016] According to an embodiment, a coefficient of friction between the coating and steel is lower than a coefficient of friction between steel and steel.

[0017] According to an embodiment, the coating is sprayed onto the surface by a thermal spray process.

[0018] According to an embodiment, the coating is sprayed onto the surface by a cold spray process.

[0019] According to an embodiment, the thermal spray process is selected from a group consisting of twin wire arc spray, high velocity oxygen fuel spray, high velocity air fuel spray, and plasma spray.

[0020] According to an embodiment, the coating comprises a fully or partially amorphous metal alloy.

[0021] According to an embodiment, the amorphous metal alloy has a composition represented by a formula Fe _a (Cr, Mo) _b (B, C) _c M _d , wherein a is a weight percentage of Fe, b is a sum of weight percentages of Cr and Mo, c is a sum of weight percentages of B and C, M is one or more transition metals and d is a sum of weight percentages of all transition metals.

[0022] According to an embodiment, values of a are from 40 to 56, values of b are from 40 to 50, values of c are from 4 to 6, and value of d are from 0 to 10.

[0023] According to an embodiment, a weight percentage of B is equal to or smaller than a weight percentage of C

[0024] According to an embodiment, a weight percentage of Mo is smaller than a weight percentage of Cr.

[0025] According to an embodiment, the amorphous metal alloy has a melting point of less than or equal to 1 150 °C. [0026] According to an embodiment, the coating further comprises particles selected from the group consisting of tungsten, carbides and borides, wherein the particles are distributed in a matrix of the amorphous metal.

[0027] According to an embodiment, the component comprises a metal, selected from a group of consisting of steel, aluminum, titanium, and cast iron.

[0028] According to an embodiment, the method further comprises roughening the surface prior to spraying the coating.

[0029] According to an embodiment, the coating has a neutral or compressive residual surface stress.

[0030] Disclosed herein is a component suitable for underground use, comprising at least a portion with a coating thereon, wherein the coating is at least partially amorphous.

[0031] According to an embodiment, the component is a drill pipe, workstring tubing, or production pipe.

[0032] According to an embodiment, the portion is a mid-section of the drill pipe.

[0033] According to an embodiment, the portion comprises a part of a tool joint.

[0034] Disclosed herein is a method of drilling a well in ground, comprising: obtaining a drill string comprising a drilling bit and a plurality of drill pipes connected thereto, wherein at least a portion of the drill pipes comprises a coating thereon, the coating being at least partially amorphous; driving the drilling bit.

[0035] According to an embodiment, the well is not straight.

[0036] According to an embodiment, the well has a section horizontal to ground. [0037] According to an embodiment, the well has a section not horizontal to ground.

[0038] Disclosed herein is a system for drilling a well in ground, comprising: a drilling bit; a plurality of drill pipes connected to one another; wherein the drilling bit is connected to the drill pipes; wherein at least a portion of the drill pipes comprises a coating thereon, the coating being at least partially amorphous.

[0039] According to an embodiment, the system further comrpises a chain tong, a degasser, a desander, drawworks, an elevator, a mud motor, a mud pump, or a mud tank.

Brief Description of Drawings

[0040] Fig. 1 is a schematic drawing illustrating a drill pipe with abrasion resistant overlays on the tool joint at an end of the pipe for connection with an end of an adjoining pipe in a drill string.

[0041] Fig. 2 is a side view of a mid-section of a drill pipe to which an amorphous metal alloy coating has been sprayed according to an embodiment.

[0042] Fig. 3A is a cross sectional scanning electron microscope (SEM) image of a sprayed coating of fully amorphous metal alloy on the drill pipe of Fig. 2 taken along the section line III-III showing the microstructure of the drill pipe, the fully amorphous metal alloy coating and the mechanical bond therebetween.

[0043] Fig. 3B is a cross sectional scanning electron microscope (SEM) image of the sprayed partially amorphous metal alloy coating on the drill pipe of Fig. 2 taken along the section line III-III showing the microstructure of the drill pipe, the partially amorphous metal alloy coating and the mechanical bond therebetween. [0044] Fig. 4A and Fig. 4B are schematic diagrams of respective thermal spray systems for applying a coating on the outer surface of the mid-section of a drill pipe.

[0045] Fig. 5 A shows a characteristic of a fully amorphous portion of the thermal sprayed coating material, Sample 1 in Fig. 3A, obtained by XRD (x-ray diffraction) showing absence of any crystalline microstructure in the coating material.

[0046] Fig. 5B shows a loading-unloading indentation curve for Sample 1 obtained from the instrumented nanoindentation test from which the modulus of elasticity, Young's modulus, of the coating can be determined.

[0047] Fig. 6A shows a characteristic of a partially amorphous portion of the thermal sprayed coating material, Sample 2 in Fig. 3B, obtained by XRD (x-ray diffraction) showing multi-phase crystalline microstructure co-existing in the mostly amorphous matrix.

[0048] Fig. 6B shows a loading-unloading indentation curve for the Sample 2 of Fig. 6A obtained from the instrumented nanoindentation test from which the modulus of elasticity, Young's modulus, can be determined.

[0049] Fig. 7 depicts the DSC (differential scanning calorimetry) of fully amorphous coating material showing clear glass transition and melting temperature.

[0050] Fig. 8 is a cross sectional scanning electron microscope (SEM) image of a sprayed coating with tungsten carbide particles in a partially amorphous metal alloy matrix on the drill pipe of Fig. 2 taken along the section line III-III showing the microstructure of the drill pipe, the partially amorphous metal alloy coating and the mechanical bond therebetween. [0051] Fig. 9 shows a high magnification scanning electron microscope (SEM) image of the coating of Fig. 8 showing tungsten carbide particles in the partially amorphous alloy matrix and identifying zones of interest.

[0052] Fig. 10 shows the chemical composition of the zones of interest identified in Fig. 9, as determined by energy-dispersive X-ray (EDX) spectroscopy, verifying the composition of the tungsten carbides and the partially amorphous alloy matrix (spectra shifted vertically for clarity).

[0053] Fig. 1 1 shows a loading-unloading indentation curve for the sample of Fig. 8 obtained from the instrumented nanoindentation test from which the modulus of elasticity, Young's modulus, can be determined.

[0054] Fig. 12 shows a hardness vs. displacement curve for the sample of Fig. 8 obtained from the instrumented nanoindentation test from which the hardness can be determined.

Detailed Description

[0055] The disclosure herein may be useful in improving protection or resistance to wear of components for underground use, such as a drill pipe or production pipe, without increasing the risk of failure of the component.

[0056] According to an embodiment, at least a portion of a component for underground use (e.g., drill pipe, production pipe) may be thermal-sprayed with a coating that has a high elastic strain limit exceeding the strain of the component in underground use (e.g., by the bending of the drill pipe as it goes downhole). The portion thermal-sprayed with the coating may include a portion of the component (e.g., mid-section of a drill pipe) that may directly contact, or may rub against a structure underground. The coating may comprise an amorphous metal alloy. The coating may comprise an at least partially amorphous, non-crystalline, disordered atomic-scale structure. The coating may have a higher hardness than the surface of the component on which it is disposed. The coating may be mechanically bonded to the underlying surface of the component without using a metallurgical bond. When the component is a drill pipe, the coating may improve wear resistance or spalling resistance against thermal shock and thermal cycling of the drill pipe, without increasing risk of failure in the drill pipe. The hardness of the coating may be greater than or equal 500 HV (Vickers), as compared with only about 310 HV for steel usually used in a drill pipe. The modulus of elasticity of the coating may be at most 150 GPa, or at most 120 GPa, as compared with around 200 GPa for steel usually used in a drill pipe. The friction coefficient between the coating and steel may be lower than that between steel (usually used in a drill pipe) and steel. For example, the friction coefficient between the coating and steel may be at most 0.15.

[0057] The coating may be a band (e.g., a band along the circumference of a drill pipe). The coating may have other configurations such as a spiral (e.g., a spiral along the drill pipe). The coating could be applied on the mid-section or other parts of a drill pipe. The coating may be built up using multiple passes of thermal spraying an amorphous metal alloy to a thickness of, for example, 0.005 to 0.1 inch. The coating may be applied to the component (e.g., a drill pipe) by a thermal spray process, which may be selected from but not limited to the group consisting of twin wire arc spray, high velocity oxygen fuel, and high velocity air fuel, and plasma sprays. The coating may be applied to the component (e.g., a drill pipe) by a cold spray process.

[0058] The amorphous metal alloy included in the coating may be in the form of a powder or wire having a composition consisting essentially of Cr 25 - 27%, B 2.0 - 2.2%, Mo 16 ~ 18%, C 2.0-2.5%, Fe balance, expressed in weight percent. Table 1 shows exemplary compositions of the amorphous metal alloy that may be included in the coating.

Table 1

[0059] In an embodiment, the amorphous metal alloy included in the coating may have a composition represented by the formula Fe _a (Cr, Mo) _b (B, C) _c Ma, where a is the weight percentage of Fe, b is the sum of the weight percentages of Cr and Mo, c is the sum of the weight percentages of B and C, M is one or more transition metals and d is the sum of the weight percentages of all transition metals. The values of a may be from 40 to 56. The values of b may be from 40 to 50. The values of c may be from 4 to 6. The value of d may be from 0 to 10. In an embodiment, the weight percentage of B is equal to or smaller than the weight percentage of C. In an embodiment, the weight percentage of Mo is smaller than the weight percentage of Cr.

[0060] When the coating is applied by a thermal spray process, the melting point of the amorphous metal alloy may be less than or equal to 1150 °C. A relative low melting point of the amorphous metal alloy reduces heat input to the base material during coating. The low heat input during coating avoids or reduces undesirable metallurgical changes to the base material. When the coating is applied to a drill pipe with a corrosion resistant layer on the inside of the drill pipe, the low heat input also avoids or reduces undesirable metallurgical changes to the corrosion resistant layer. The low melting point of the amorphous metal alloy, also contributes to the formation of the amorphous microstructure of the coating.

[0061] The amorphous metal alloy may act as a matrix material of the coating when the coating also includes at least one of wear resistant particles selected from the group consisting of tungsten, carbides and borides. The wear resistant particles may be pre-mixed into the amorphous metal alloy powder or wire, or be incorporated during the spray.

[0062] Fig. 2 schematically shows a partial view of a drill pipe 1 , as an example of the component, with the coating 5, according to an embodiment. The drill pipe 1 is connected to another drill pipe at a tool joint 2. The coating 5 may be applied to a portion such as the mid-section 4 of the drill pipe 1. The coating 5 may have an elastic strain limit greater than the strain that the component (e.g., drill pipe 1) will experience from being used underground (e.g., used in drilling, caused by, for example, the bending of the drill pipe during drilling from vertical to horizontal). The component may experience strain up to 0.103%. The coating 5 may have an elastic strain limit greater than the yield strain of the component, which may be from 0.076 to 0.155%. For example, the coating 5 may endure strain such as 0.17% before it fails. The coating 5 may have a higher modulus of elasticity than the component. The coating 5 in this example has a modulus of elasticity of < 150 GPa, or < 120 GPa, lower than the Young's modulus of the drill pipe 1. The Young's modulus of elasticity E of the steel usually used in drill pipes is about 29 x 10 ⁶ PSI (200 GPa). The coating 5 may have a higher strength (hardness) than that of the surface of the component (e.g., drill pipe 1) over which it is applied. Coating 5 in this example has a hardness is > 500 HV (Vickers hardness). The hardness of the steel usually used in drill pipes is about 310 HV. The higher hardness, the lower modulus of elasticity, the higher elastic strain limit or their combination of the coating 5 may be attributed to, at least in part, that the coating has an atomic microstructure that is at least partially, or fully, amorphous, rather than a crystalline atomic structure, and may make the coating more wear resistant in unground use.

[0063] According to an embodiment, to form the coating 5, the amorphous metal alloy is applied to the outer surface of a portion (e.g., the mid-section 4) of a component (e.g., the drill pipe 1) by a thermal spraying process, (e.g., using a twin wire arc spraying system as schematically depicted in Fig. 4A. In the process, two wires, 6 and 7, of the amorphous metal alloy are fed through a wire feed 8 and electrically charged, one positive and one negative. The wires are forced together and form an electric arc, melting the wires. Compressed air, passing through a nozzle 10, atomizes the molten metal from the wires and sprays it onto the portion (e.g., midsection 4 of the drill pipe 1). By moving the component or the nozzle 10, areas of the coating may be controlled. For example, rotation of the drill pipe with the nozzle stationary results in the formation of a band about the outer surface of the mid-section of the drill pipe. The higher the current rating of the system, e.g., 350 amps, 700 amps, etc., the higher the spray rate. In the example embodiment, a system having a current rating of 200-225 amps was employed. The length of the mid-section 4 coated by the coating 5 can vary. The thickness of the coating 5 may be varied. The length and thickness may be chosen based on the expected radius of curvature to be experienced by the drill pipe during drilling, the relative diameters of the drill pipe and drill casing, etc. In the example, the middle third of the length of the drill pipe is coated, but smaller or greater lengths can be coated to reduce expected wear on the surface of the pipe during drilling. [0064] The coating may be a thin layer, on the order of 30 mil (0.030 inch) thick, for example. The thin coating experiences rapid cooling on the component (e.g., drill pipe) resulting in the formation of an at least partially, e.g., mostly (shown in Fig. 6A) or fully (shown in Fig. 5A), amorphous structure rather than a crystalline structure. Multiple passes of the thermally sprayed coating may be applied to build up the coating 5 to a desired thickness to protect the component against wear. In an example, the coating 5 has a thickness of 0.05 inch formed from multiple passes of thermal spraying. While twin wire arc spraying is used in the example, other thermal spraying processes including high velocity oxygen fuel, and high velocity air fuel, or a cold spray, plasma process could be used to apply the coating. The amorphous metal alloy of the coating could be in a powder form instead of or in addition to a wire form. Fig. 4B depicts an arrangement for spraying the powder amorphous metal alloy with a high velocity oxygen-fuel process. Wear resistant particles such as tungsten, carbides and borides could also be applied as a mixture within the amorphous metal alloy wire or powder, where the amorphous metal alloy, after the coating is deposited, serves as a matrix for the wear resistant particles. The surface of the portion to be coated may be roughened prior to coating, see Figs. 3A and 3B, for example, by grit blasting, to facilitate bonding of the coating to the surface.

[0065] The coating 5 may form a mechanical bond with the surface, as opposed to having a metallurgical bond with the surface. The mechanical bond is shown in the microstructure of the coated drill pipe depicted in Figs. 3 A and 3B. The bond strength of the coating to the surface may be in the range of 7,000 ~ 10,000 psi.

[0066] According to an embodiment, the coating 5 has a neutral or slightly compressive residual surface stress because the coating 5 sprayed on the component undergoes little or no shrinkage due to being mostly or fully amorphous. In contrast, crystalline metal coatings solidify and shrink, which leads to tensile surface stresses. Tensile surface stresses may warp the object coated in a concave manner and may cause delamination. The neutral or slightly compressive surface force in the coating 5 may enhance the bonding strength of the coating to the underlying surface.

[0067] The at least partial amorphous structure of the coating may contribute to improved resistance to wear and delamination of the coating with high cycling of certain components such as drill pipes during drilling. More specifically, one or more of Fe-Cr-B-Mo-C alloy, Ni-Cr-Si-B-Mo-Cu-Co alloy, Fe-Cr-B-Mn-Si alloy, Fe-Cr-B- Si alloy, Fe-Cr-B-Mn-Si-Cu-Ni-Mo alloy, Fe-Cr-B-Mn-Si-Ni alloy, Fe-Cr-Si-B-Mn- i-WC-TiC alloy, Fe-Cr-Si-Mn-C-Nd-Ti alloy, Fe-Cr-P-C alloy, Fe-Cr-Mo-P-C alloy, Fe-Cr-Mo-P-C-Ni alloy, Fe-P-C-B-Al alloy, Fe-Cr-Mo-B-C-Si-Ni-P alloy, Fe-Cr-Mo- B-C-Si-W-Ni alloy , Ni-Cr -Mo-B alloy, Fe-B-Si-Cr-Nb-W alloy, Fe-Cr-Mo-B-C-Y alloy, Fe-Cr-Mo-B-C-Y-Co alloy, Fe-Cr-Mo-W-Nb alloy, Fe-Cr-Mo-B-C-Si-W-Mn alloy, Fe-Cr-Si-W-Nb alloy could be used in the coating.

[0068] Figs. 5B and 6B show the results of instrumented nanoindentation tests on Samples 1 and 2 of the coating 5 as identified in Figs. 3 A and 3B. The coating 5 was thermally sprayed on a drill pipe. From the slope of the loading-unloading indentation curves of Figs. 5B and 6B obtained by the tests, the Young's modulus of elasticity was calculated to be < 120 GPa to provide, together with the high strength (hardness) of the coating, > 500 HV, an elastic strain limit greater than the strains caused by bending the drill pipe during drilling with deviation of drilling from vertical to horizontal. Figs. 5A and 6A represent XRD plots for fully amorphous coating material and partially crystalline phase containing amorphous matrix coating material. Fig. 7 depicts the differential scanning calorimetry of the coating showing clear glass transition temperature and melting temperature. [0069] According to an embodiment, the coating may be a composite comprising particles such as tungsten carbides and borides distributed in a matrix of the amorphous metal alloy of the coating. Table 2 shows compositions, Young's moduli and hardness of a homogenous coating of amorphous metal alloy "A" (Sample 1), a homogenous coating of amorphous metal alloy "B" (Sample 2), composite coatings of tungsten carbide (WC) particles distributed in matrices amorphous metal alloy "A" (Sample 4 and Sample 5), and composite coatings of tungsten carbide (WC) particles distributed in matrices amorphous metal alloy "B" (Sample 3 and Sample 6). Nanoindentation measurements were performed with a Nanoindenter XP from MTS. Indents were performed with loads up to 700 mN and with a maximum penetration depth of 2 μιη. The hardness and the Young's modulus of the coatings were determined from the load versus displacement curve in a complete load/unload cycle.

Table 2

[0070] Referring to Sample 1 of Table 2 as an exemplary embodiment, it is seen that its modulus of elasticity is 110 GPa, which is only about 55% of that of steel. Steel is commonly used in underground components such as drill pipes and other downhole tubulars. A coating having a low elastic modulus may be beneficial for the following reason. An underground component may be subjected to tensile, compression, and bending loads during downhole operation. These loads cause deflection, or in engineering terms, strain. Since the coating is mechanically bonded to the component, the coating may endure essentially the same strain as that of the component. By definition, for a given amount of strain, the lower the modulus of elasticity is, the lower is the stress. Thus a coating with a low modulus of elasticity will be subjected to a lower level of stress than a coating with a high modulus of elasticity, under a given strain. As such, a coating with a low modulus of elasticity is less likely to crack than one with a high modulus of elasticity. Although Sample 1 has a modulus of elasticity higher than that of steel, it has a hardness of 6.8 GPa, which is over twice that (3.0 GPa or so) of steel. Hardness is a general indicator of wear resistance. So it is seen that the coating of Sample 1 offers high wear resistance along with a reduced propensity to cracking from downhole loading.

[0071] Fig. 8 shows the exemplary composite coating of Sample 4 of Table 2. The coating of Sample 4 was applied with HVOF spray to a thickness of about 20 mils, over a substrate roughened by grit blasting. As indicated by Table 2, the coating of Sample 4 comprised about 20% tungsten carbide particles disposed in a partially amorphous metal alloy (Cr 25 - 27%, B 2.0 - 2.2%, Mo 16 ~ 18%, C 2.0-2.5%, Fe balance) matrix.

[0072] Fig. 9 is a high magnification image of the coating of Fig. 8. Labels 1, 2, and 3 identify locations at which the chemistry of the constituents was evaluated with EDX.

[0073] Fig. 10 shows the chemistry of the constituents at locations at Labels 1, 2, and 3 identified in Fig. 9. It is seen both optically and by chemistry that the tungsten carbide particles remain discrete and contained, but chemically unaffected, by the surrounding matrix. [0074] Referring again to Table 2, the modulus of elasticity of Sample 4 is 173 GPa, as measured by the nanoindentation method and charted in Fig. 11. This modulus of elasticity is about 87% of that of steel, and about half of that of conventional tungsten carbide coatings. The hardness, as charted in Fig. 12, is 11.6, which is nearly 4 times that of steel, and comparable to that of conventional tungsten carbide coatings. So it is seen that the coating of Sample #4 may offer greatly increased wear resistance in a coating that has a modulus similar to that of steel, and also wear resistance that may be similar to that of tungsten carbide coatings, while with a much lower modulus and thus lower propensity to crack from the strains imposed by downhole loading.

[0075] Various designs of the coating can also be sprayed including a spiral configuration, a band, or just a thin layer through the whole component. The component coated could also be formed of steel or other materials such as aluminum or titanium. Workers skilled in the art and technology to which the disclosure pertains will appreciate that alterations and changes in the described structures and processes may be practiced without meaningfully departing from the principle, spirit, and scope of this disclosure.

[0076] Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings, but rather should be read consistent with and as support to the following claims which are to have their fullest and fair scope.