Patent Application
20150367563
The present invention relates generally to methods and apparatus for protecting elongated substrates, such as wood pylons, utility poles, railroad ties and steel beams and columns. More specifically, the present invention provides methods and apparatus for a heat shrinkable protective polyvinyl chloride sleeve over a substrate and a resultant protected substrate.
Wood pylons and timbers used in marine applications have been subjected for centuries to the costly problem of marine growth and wood boring infestation. Similar problems plague terrestrial structures. Generally protection for such structures from the detrimental effect of harmful organisms is limited to surface treatments or impregnating the wood with chemical solutions to inhibit the attachment of the various infestations.
Other known attempts to protect substrates include wrapping a wood pylon in a flexible plastic sheet. A seam formed by overlapping edges is bonded closed, and the wrap is heated to shrink to a snug fit. The overlapping edges that form the seam comprise double the width of the material of the sheet. Consequently, the heat that is sufficient to shrink the wrap away from the seam is insufficient to shrink the double width seam. Thus, a gap may be formed at the seam that allows intrusion by water and marine organisms. Furthermore, shrinkage of the wrap exerts tensile and shear stresses at the seam. These stresses may compromise the integrity of the seam, causing further intrusion.
Another problem with prior art wraps is failure to bond sufficiently to an underlying substrate. In particular a wood pylon has inherent surface irregularities such that a high viscosity hot melt adhesive disposed between a wrap and a wood pylon requires considerable pressure to bond with the wrap to the wood pylon. Various techniques and devices for applying pressure while heating have been devised. However, these devices are costly and cumbersome and time consuming to use. Additionally, these devices are prone to applying pressure over targeted areas, with considerable pressure gradients between targeted areas and other areas. This can result in uneven and weak bonding, which increases risk of de-bonding (i.e., delamination) and formation of gaps that are vulnerable to intrusion.
Yet another problem with prior art is that known protective wraps may be limited to use with certain materials and shapes. A protective cover suitable for use with a variety of substrates and shapes, whether or not used in marine applications, is needed.
Heat shrinkable tubing has been known wherein a material may be expanded from a heat stable condition to a thermally unstable condition and returned to a heat stable condition with the application of an appropriate amount of thermal energy. Such tubing is generally used in conjunction with covering of wires and is commercially available. However, due to the nature of polyvinyl chloride, extrusion of such tubing is limited to diameters of two inches or less. Diameters greater than about two inches experience tears or thin areas that result in aneurisms when the tube is placed under stress. In addition, during the manufacturing process, a larger diameter PVC tube will collapse under its own weight while in a heated condition and destroy itself.
Accordingly, the present invention provides a heat shrinkable protective coating for protecting a substrate from deleterious elements present in environments in which the substrates are deployed and methods and apparatus for manufacturing a heat shrinkable coating of suitable length and girth to coat a pylon substrate or building girder. More specifically, the present invention provides a heat shrinkable protective coating for protecting a curvilinear substrate with a cross section of generally two inches or greater in diameter, and in preferred embodiments a diameter of four inches or greater or an angular shaped substrate with a diagonal cross section of generally two inches or greater and preferred embodiments a diagonal of four inches or greater. The present invention also includes methods and apparatus for manufacturing said heat shrinkable coating. In some embodiments an end cap may also be deployed to further encapsulate the substrate or girder.
As discussed more fully below, in some exemplary implementations of the present invention, a continuously extruded seamless polyvinyl chloride (“PVC”) pipe is manufactured from a combination of a unique PVC compound and a specialized extrusion process is provided that enables the pipe to be expanded to a thermally unstable diameter about 100% larger that a heat stable state, wherein a manufactured PVC pipe will shrink to about 50% of its manufactured size when reheated to a specific temperature.
In some aspects of the present invention, a manufactured PVC pipe can be positioned surrounding a substrate, such as a wooden beam for a pylon, or other timber, tie, column or dimensional lumber. Upon application of heat, the pipe will shrink from a thermally unstable expanded diameter towards a thermally stable unexpanded diameter and thereby encapsulate the substrate with a hermetically sealed, robust membrane. This seamless impervious membrane will generally protect the substrate from environmental conditions and offset the ability of an internal wood boring or surface destroying organism to negatively interact with the wooden substrate.
In some embodiment, the shrinkable pipe has a continuous or intermittent coating of a heat sensitive adhesive applied to its inner wall after extrusion and expansion, so that when the PVC pipe is shrunken to assume a shape based upon a surface of the substrate, the adhesive creates a bond between the shrunken substrate and the PVC pipe. The substrate being encapsulated can be of suitable length for building materials, pylons, tapering or parallel, treated or untreated with a diameter of between about 4 inches up to about 24 inches, based in part upon a thickness of the tube, and dimensions of a relevant extrusion die and expansion mandrel.
A method of protecting a structure (e.g., a wood pylon, railroad tie, dimensional lumber or other wood or metal structure) according to principles of the invention entails encasing at least a portion of the substrate in a heat shrinkable seamless PVC pipe.
According to the present invention, a heat shrinkable pipe is produced by heating a PVC dry blend until a melt is formed. The blend may include a fungicide. The melt is extruded through a die to form a seamless PVC pipe having an outer surface, an inner surface and an unexpanded inner diameter greater than about four inches.
The extruded PVC pipe is cooled to a first temperature below a glass transition temperature for the PVC pipe. After cooling, the extruded PVC pipe is heated to a second temperature of at least about the glass transition temperature for the PVC pipe. After heating the extruded PVC pipe to the second temperature, the PVC pipe is expanded from the unexpanded thermally stable inner diameter to an expanded thermally unstable inner diameter. The unexpanded inner diameter is generally about one half (for example, from between about 25% to 75%) of the expanded inner diameter.
A maximum width of the substrate to be coated (for example, a maximum diameter of a curvilinear substrate or a maximum diagonal of an angular substrate) is between the unexpanded thermally stable inner diameter of the PVC pipe and a thermally unstable expanded inner diameter of the PVC pipe.
Optionally, after expansion, one or both of a sealant and an adhesive may be applied onto at least a portion of an inner surface of the PVC pipe. In some embodiments, a hot melt adhesive with a relatively low viscosity when melted (e.g., less than 15,000 centipoise) may be applied. In a further aspect, in some embodiment, a fungicide may be included in one or both an adhesive or a sealant. After expanding, the PVC pipe may be cooled to a second temperature below the glass transition temperature for the PVC pipe and the PVC pipe may be cut to a determined size.
The step of expanding the PVC pipe entails passing the PVC pipe over a mandrel having a first cylindrical section with a first mandrel diameter about equal to the unexpanded inner diameter, and a second cylindrical section with a second mandrel diameter about equal to the expanded inner diameter, and a conical frustum disposed between and coupling the first cylindrical section to the second cylindrical section. The conical frustum, first cylindrical section and second cylindrical section are concentric. The mandrel may also include several sizing discs, each having a disc diameter about equal to the expanded inner diameter. Each of the sizing discs is concentric with the second cylindrical section and spaced apart from each other and the second cylindrical section. A negative atmospheric pressure may be maintained around the outer perimeter of the pipe at the mandrel as the PVC pipe passes over it during expansion.
In another aspect, positive atmospheric pressure may be provided in the interior of the PVC pipe as the PVC pipe is heated. The positive atmospheric pressure may be provided via a pressurized gas, such as an inert gas, or air. An inert gas may include nitrogen. The pressure may be maintained within the PCV pipe via the use of plug inside the pipe that obstruct the flow of the atmospheric gas in the interior of the PVC pipe. In some preferred embodiments, the positive atmospheric pressure is between about 20 to 30 psi (pounds per square inch) and provide pressure against an inner surface of the PVC pipe in an outward direction.
A cut segment of pipe is slid over at least a portion of the substrate (e.g., pylon, tie or other timber).
In still another aspect of the present invention, the substrate may be lifted with a forklift, such as a forklift equipped with a cylindrical sleeve for holding the structure in a cantilever manner on the forks. A heat source heats the PVC pipe on the substrate until the temperature of the PVC pipe reaches the glass transition temperature for the PVC pipe, whereupon exposure to the heat shrinks the PVC pipe from the thermally unstable expanded inner diameter towards the thermally stable unexpanded inner diameter to a shape tightly following the surface of the substrate.
In those embodiments involving a hot melt adhesive, heating melts the adhesive and the shrinking action compresses the adhesive into the structure, thereby forming an intimate bond between the substrate, the adhesive and the inner surface of the PVC pipe. Afterwards, the PVC pipe is allowed to cool forming a PVC membrane of a shape closely following the surface topography of the underlying substrate. After cooling, the substrate encased with the PVC membrane may be deployed for use or further fitted with endcaps, such as PVC endcaps.
The foregoing and other aspects, objects, features and advantages of the invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where:
Those skilled in the art will appreciate that the figures are not intended to be drawn to any particular scale; nor are the figures intended to illustrate every embodiment of the invention. The invention is not limited to the exemplary embodiments depicted in the figures or the specific components, configurations, shapes, relative sizes, ornamental aspects or proportions as shown in the figures.
The present invention provides for a substrate with protective coating. The protective coating is functional to protect the substrate from exposure to deleterious elements present in environments in which the substrates may be deployed. The present invention also includes methods and apparatus for manufacturing the substrate coating in the form of a PVC pipe of suitable length and diameter to encapsulate a substrate, such as for example a wooden pylon, a timber or building girder. More specifically, the present invention provides a PVC pipe with a thermally unstable expanded diameter and a thermally stable unexpanded diameter that is heat shrinkable to protect a curvilinear substrate four inches or greater in diameter or an angular shaped substrate four inches with a diagonal of four inches or greater and methods and apparatus for manufacturing said heat shrinkable coating. In some embodiments an end cap may also be deployed to further encapsulate the substrate or girder.
To solve one or more of the problems set forth above, in some exemplary implementations of the present invention, a continuously extruded seamless polyvinyl chloride (“PVC”) pipe is manufactured from a combination of a unique PVC compound and a specialized extrusion process is provided that enables the PVC pipe to be expanded to a thermally unstable diameter about 100% larger that a thermally stable state diameter, wherein a manufactured PVC pipe may shrink to about 50% of its manufactured size when heated to a specific temperature.
Referring now to
A dry blend PVC compound to be extruded into heat shrinkable pipe may include components to both reflect and absorb ultra-violet rays, coloring pigments, process stabilizers, flexibility enhancers, surface migrating ablative fungicides/biocides and algaecides. A non-limiting example of an exemplary blend is provided below in Table 1. It is understood that various blends may in include all or some subset of the following listed components:
A motor 100 powers one or more screws of an extruder 110. The extruder heats the raw material supplied through a hopper 105, and forces the resulting melted polymer through an extrusion die 120. The molten polymer leaves the extruder die 120 in the form of one or more ribbons or molten streams.
Optionally, in some embodiments a heated receptacle 115 and gear pump may supply hot melt adhesive through a heat resistant (e.g., nylon) tube that passes through the die spider located in the mid region of the extruder die 120 and continues to connect through the sizing mandrel 145 and subsequently to the hot melt adhesive applicator 147 where the hot melt is evenly sprayed on the interior wall of the blown (i.e., expanded) pipe.
The extrusion die 120 supports and distributes the homogeneous polymer melt around a solid mandrel, which forms the homogeneous polymer melt into an annular shape for a solid wall pipe. The formed solid wall pipe is sometimes referred to herein as a “sleeve.” The formed pipe is seamless, though it may exhibit artifacts from the extrusion process.
The invention is not limited to PVC pipes with an adhesive applied to the inner surface. In embodiments having the adhesive, the invention is not limited to the applicator 125 described above. The adhesive may be co-extruded or applied in any other manner suitable for a continuous extrusion process.
Non-limiting examples of hot melt adhesives include ethylene-vinyl acetate copolymers; ethylene-acrylate copolymers, such as ethylene-vinylacetate-maleic anhydride and ethylene-acrylate-maleic anhydride terpolymers, ethylene n-butyl acrylate, ethylene-acrylic acid and ethylene-ethyl acetate; polyolefins, such as amorphous polyolefin polymers; polybutene-1 and its copolymers; polyamides; thermosetting polyurethanes; styrene copolymer adhesives and rubber-based adhesives, such as styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene/butylene-styrene, and styrene-ethylene/propylene.
To adjust viscosity of the melt, tackifying resins and waxes may be added in varying amounts to the adhesive. Tackifying resins may include rosins and their derivates, terpenes and modified terpenes, aliphatic, cycloaliphatic and aromatic resins, hydrogenated hydrocarbon resins, and terpene-phenol resins. Waxes may include microcrystalline waxes, fatty amide waxes or oxidized Fischer-Tropsch waxes, which lower the melt viscosity and can improve bond strength and temperature resistance. A hot melt adhesive with a softening point of less than 250° F. and a viscosity at 350° F. of 15,000 centipoise or less is preferred. The adhesive melts during heat shrinking and flows freely into and bonds well with the substrate, without requiring pressure beyond the pressure exerted by the seamless shrinking pipe.
In a particular embodiment the adhesive is comprised of ethylene vinyl acetate (EVA) with a viscosity of about 10,500 centipoise at 350° F. The heat application used to shrink the pipe reactivates the EVA and provides a strong but flexible bond between the substrate and the PVC pipe.
The dimensions and heat shrink properties of the PVC pipe are determined and set during sizing, reheating and cooling operations. A sizing operation holds the pipe in its proper dimensions during cooling of the material. The process is accomplished by drawing the hot material from the extruder die 120 through a sizing sleeve 130 upstream of a cooling tank 135. Sizing may be accomplished by using either vacuum or pressure. By way of example, in a vacuum sizing system, hot extrudate is drawn through a sizing tube 130 or rings while its surface is cooled enough to maintain proper dimensions and a circular form. The outside surface of the pipe may held against the sizing sleeve by vacuum or negative pressure.
After the pipe exits the vacuum sizing tank 130, it is moved through one or more spray or immersion cooling tanks 135. Various methods of cooling may be utilized to remove residual heat from the pipe. The system may use either total immersion or spray cooling, though spray cooling is usually applied to large diameter pipe where total immersion would be inconvenient.
Cooling water temperatures may be in the range of 40° to 55° F. The cooling tank 135 may contain annealing zones to minimize residual stresses by allowing heat contained within the inner pipe wall to radiate outward and anneal the entire pipe wall. The total length of the cooling bath must be adequate to cool the pipe below its glass transition temperature (tg), e.g., below about 175° F. or whatever the tg is for the particular pipe, in order to set an initial unexpanded diameter. In an exemplary implementation, the pipe is cooled to about 150° F. to 120° F. to continue processing.
As drawn through the cooling tank 135, the pipe solidifies from the outside of the wall to the inside of the wall. To cool to a state to continue processing, heat energy stored within the wall of the product is transferred to the water of the cooling tank on the outside of the product. The thinner the wall of the final product, the faster it will cool to the desired temperature. The heavier the wall of the product, the slower it will transfer heat and cool to a uniform solid state. As a poor thermal conductor, the plastic absorbs and relinquishes heat fairly slowly.
In some embodiments, a thermal conductivity of the resin is a fixed value, wherefore heat will only be transferred at given rate. In such embodiments, decreasing a temperature of the cooling water in the cooling tank 135will not increase the thermal energy transfer rate.
After emerging from the cooling tank 135, the PVC pipe may be reheated in reheater 140. The reheater 140 contains one or more heating elements configured to raise the temperature of the pipe to its glass transition temperature or slightly above the glass transition temperature. By way of example and not limitation, the temperature of the pipe may be increased to about 160° F. to 190° F. in the reheater 140.
PVC resin melts when its temperature becomes higher than its melting point and becomes softened and amorphous, but as it is gradually cooled from the softened and amorphous state its viscosity gradually increases, and it goes into a rubbery state and finally solidifies. The rubbery state lends softness and flexibility to the polymer. The temperature at the border from the rubbery state to the solid state (called the glass state) is called its “glass transition temperature.” The glass transition temperature is generally indicated as Tg. The glass transition temperature for PVC depends upon the cooling rate and molecular weight distribution and may be influenced by additives. Without plasticizer, the Tg for PVC is about 158° F. to 90° C. 194° F. For a plasticized PVC, the Tg may be about 125° F. to 60° C. 150° F. As a rule of thumb, most polymers will have a ratio of Tg/Tm of between 0.50 and 0.75, where Tm is the polymer's melting point (° K). A precise glass transition temperature may be determined for a particular PVC dry blend by differential scanning calorimetry.
Differential scanning calorimetry or DSC is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and a reference is measured as a function of temperature. The reference has a well-defined heat capacity over the range of temperatures to be scanned. Both the sample and a reference are maintained at nearly the same temperature throughout a test. When the sample undergoes a physical transformation such as a phase transition, more or less heat will need to flow to it than the reference to maintain both at the same temperature. For example, as a PVC sample melts to a softened and amorphous it will require more heat flowing to the sample to increase its temperature at the same rate as the reference. This is due to the absorption of heat by the sample as it undergoes the endothermic phase transition from solid to softened and amorphous. By observing the difference in heat flow between the sample and reference, differential scanning calorimeters are able to measure the amount of heat absorbed or released during such transitions as well as during more subtle physical changes, such as glass transitions.
After emerging from the reheater 140, the pipe passes over an expander 145 (aka sizing mandrel) where its diameter is increased, e.g., doubled.
Referring now to
For example as illustrated in
The First Plug 136 allows for a positive atmospheric pressure to be provided into the PVC pipe downstream of the First Plug 136 and prevents the positive atmospheric pressure from backing up into the pipe in the cooling chamber 135A. In preferred embodiments, the positive atmospheric pressure is present while the PVC pipe is in a heater 142. The positive atmospheric pressure may be supplied, for example via air or other gas into the interior of the PVC pipe. Some preferred embodiments include pumping an inert gas into the interior of the PVC pipe. The inert gas may include, for example, nitrogen.
A Second Plug 139 may include an expansion plug and the positive atmospheric pressure interior to the PVC pipe may help the PVC pile to uniformly expand over the expansion plug 139, even though the expansion plug is a high diameter plug as compared to previously known processes. The second lug may also be held in place via a restraint 138B.
Third plug may include an air seal plug for maintaining the positive atmospheric pressure within the PVC pipe and be held in place via a third restraining mechanism 138C.
Referring now to
The expanded diameter may be double the unexpanded diameter. The pylon diameter will be between the expanded diameter and the unexpanded diameter. In a preferred implementation, the pylon diameter is about midway between the expanded diameter and the unexpanded diameter.
Optionally, a continuous or intermittent coating of a heat sensitive adhesive may be applied to the inner wall of the extruded pipe after extrusion and expansion, so that when the pipe is heat shrunk to take the shape of the substrate (e.g., pylon) the adhesive creates a bond between the substrate and the PVC pipe.
By way of example and not unclaimed limitation, an adhesive applicator 147 may be provided downstream of the sizing mandrel 145. As the expanded pipe emerges from the sizing mandrel 145, hot melt adhesive is applied to the inner wall of the pipe. As conceptually illustrated in
After the reheated expanded pipe emerges from the expander 145, it enters another cooling tank 150, i.e., another spray or immersion cooling tank. The cooling tank 150 cools the pipe below its glass transition temperature (tg) in order to set an expanded diameter. In an exemplary implementation, the pipe is cooled to below the tg.
As the pipe emerges from the cooling tank 150, it has a diameter referred to herein as the expanded diameter. This diameter may be, for example, about eight inches. During heat shrinking, the diameter of the pipe will shrink from the expanded diameter towards the unexpanded diameter. This expanded diameter should be set to be greater than the diameter of the substrate.
The pipe is not limited to a structure having a circular cross section. Structures having non-circular cross section shapes (e.g., rectangular) may be produced in accordance with the principles of the invention. Thus, for examples, pipes having rectangular cross section shapes may encapsulate lumber and ties having rectangular cross section shapes. Additionally, pipes having shapes that differ from the shape of the substrate (e.g., a circular cross section pipe over a rectangular cross section substrate) may encapsulate the substrate. The heat shrinking action is sufficient to form a tight seal.
Pullers 137, 155 provide the necessary forces to pull the pipe through the entire post extrusion operation. The pullers also maintain the proper wall thickness control by providing a constant pulling rate. The first puller 137 controls the wall thickness of the pre-expanded pipe and prevents the second puller 155 from influencing the pipe as it is drawn from the die. The second puller 155 controls the wall thickness of the expanded pipe. The rate at which the pipe is pulled, at least in part, determines the wall thickness of the finished pipe. Increasing the puller speed at a constant screw speed may reduce the wall thickness, while reducing the puller speed at the same screw speed may increase wall thickness. The two pullers may be electronically controlled and linked to precisely control the wall thickness of the expanded pipe.
The pipe is then cut by a cutter 160 into specified lengths for bundling, storage and shipping. The pipe may be cut into any desired lengths (e.g., 8, 10, 12, or 16 feet). Lengths that are not greater than 40 to 50 feet can be shipped easily by rail or truck. Bundling provides ease of handling and safety during loading and unloading.
The extrusion line may have one or more printing stations for printing notations on the pipe. An on-line gauging system may measure the product's outer diameter with a laser-based scanner. Such laser gauging systems have a very high measurement accuracy and a very high scanning rate for measurement averaging. Such gauging scanners are usually placed in the extrusion line after cooling and before the belt puller.
Referring now to
Referring now to
The pylon holder 600 is used to lift a pylon by an end, so that the extruded pipe may be slid onto the pylon from the opposite end.
After the sleeve is correctly positioned over the portions of the pylon to be protected, it is shrunk by applying heat, as in step 1010. Sufficient heat should be applied to raise the temperature of the pylon to its glass transition temperature or slightly higher. In general as the substrate is positioned within the inner diameter of the PVC pipe, the thermally unstable expanded diameter is heated and the PVC pipe tries to return to the thermally stable unexpanded diameter causing the PVC pipe to shrink around the substrate as the substrate prevents the PVC pipe from returning fully to the stable unexpanded diameter.
The heat may be applied using one or more torches, heat lamps, steam and resistive heating elements. The heat source may be moved along the periphery of the sleeve to heat all portions of the sleeve as evenly as reasonably possible. This reheat causes the pipe to regress towards its original unexpanded extruded form, toward the unexpanded diameter.
After heat shrinking, the covered pylon may be allowed to cool briefly and then removed from the holder, as in step 1015. After removal, the protected pylon may be deployed for use.
Referring now to
In
In
The resulting product is a pylon with a seamless PVC shrink-wrapped sleeve covering at least a portion of the pylon. By omitting seams, the product avoids risk of delamination and gapping that may allow intrusion by water and/or organisms.
A fungicide may be included in one or both of the PVC dry blend and the hot melt adhesive. Any fungicide suitable for extrusion processing and marine applications may be utilized within the scope of the present invention. Alternatively, a fungicide coating may be applied to the surfaces of the pipe after manufacturing.
Referring now to
Similarly, a cross section of a curvilinear substrate 1803 is illustrated with a generally round cross section. The curvilinear cross section is shown concentrically with a thermally stable unexpanded sleeve (PVC pipe) diameter 1804 and a thermally unstable expanded diameter 1805. The thermally unstable unexpanded sleeve diameter 1805 is large enough for the PVC pipe to slip over the curvilinear substrate and the thermally stable unexpanded diameter 1804 is small enough such that when a PVC pipe around the curvilinear substrate is heated, the PVC pipe will shrink and conform to the shape of the curvilinear substrate 1800 essentially tightly coating the curvilinear substrate 1803.
Referring now to
Accordingly, implementations of the present invention may include a substrate including a wooden pylon with a diameter of any given cross section of between about six inches and fourteen inches. Similarly, implementations may include a timber beam with an angular shape such as a square or a rectangle, with each side of the timber beam between about six inches and twelve inches,
As illustrated, in another aspect, an overlap of the first sleeve and the second sleeve allows for the entire tapered, or frustum shaped substrate to be encapsulated with PVC pipe 1902-1903.
Substrates to be protected by the pipe may comprise wood pylon, dimensional lumber, railroad ties, fence posts, elongated metal structures such as steel beams, columns and posts, and the like. Any elongated structure having a diameter or maximum width that is less than the inner diameter or width of the pipe may be protected by the pipe. The pipe does not have to cover the entirety of the substrate. Rather, only the portion requiring protection may be covered. In some cases, the entirety of the substrate may require protection. In other cases, only a portion (e.g., a submerged portion) may require protection.
The pipe is not limited to a circular cross section. Other shapes, including but not limited to rectangular, I-beam, L, U, and other curvaceous or polygonal shapes may be produced within the scope of the invention.
With reference to
With reference to
While an exemplary embodiment of the invention has been described, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. With respect to the above description then, it is to be realized that the optimum relationships for the components and steps of the invention, including variations in order, form, content, function and manner of operation, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. The above description and drawings are illustrative of modifications that can be made without departing from the present invention, the scope of which is to be limited only by the following claims. Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents are intended to fall within the scope of the invention as claimed.
This application claims priority as a continuation in part to U.S. NonProvisional patent application Ser. No. 14/312,663, filed Jun. 23, 2014, and titled “EXTRUDED HEAT SHRINK PROTECTIVE SEAMLESS PVC PILING SLEEVE AND METHOD”, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14312663 | Jun 2014 | US |
| Child | 14746912 | US |
