Utility pole structure and manufacturing method thereof

Abstract

A pole comprising a wood core, a fiberglass layer surrounding the wood core, and an outer coating layer surrounding the fiberglass layer. The outer coating layer comprising a polymeric material. The wood core has a moisture content between 8-12% prior to the application of the fiberglass layer. The pole is configured for use as a utility pole, marine pier, fence post, or structural member of a building.

Description

UTILITY POLE STRUCTURE AND MANUFACTURING METHOD THEREOFCLAIM FOR PRIORITY

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 704,212, filed on October 7, 2024, and titled, “Unity Pole Structure and Manufacturing Method Thereof,” the entire contents of which are herein incorporated by reference.TECHNICAL FIELD

[0002] The subject matter described herein relates to pole structures and methods for manufacturing the same.BACKGROUND

[0003] Utility poles represent a broad class of structures providing for the hanging or mounting of transmission cables, electrical equipment, and other devices above the ground or attached to buildings. Examples are poles for electricity transmission and distribution infrastructure, telecommunications lines and equipment, antennas, lighting poles, traffic signals, cameras and sensors, and signage. The number of utility poles for the power grid alone in the United States is estimated to be over 150 million, with estimates of well over 1 billion globally. Fabrication and maintenance of utility poles consumes vast resources in terms of material and energy expended in their manufacture.

[0004] A report by Oak Ridge National Laboratory summarized the role of utility poles in public infrastructure. “The importance of the standard utility pole cannot be overstated. There are approximately 150 million utility poles in service in the US that are responsible for the transmission approximately 38 Quads of electricity to 330 million people. These poles aredesigned to last many decades and be exposed to extreme weather including large swings in temperatures, humidity, wind, ice as well as insects and animals. During severe climate events (hurricanes, ice storms, fires) failure of power poles leads to loss of electrical power when it is needed the most.” Oak Ridge National Laboratory, May 2021 . Report ORNL / TM-2021 / 2068

[0005] Wooden poles represent the vast majority of all utility poles in use today. While wood offers one of most cost effective and sustainable of construction materials, it has significant drawbacks when used for utility poles. A primary concern is the requirement to infuse wood poles with preservatives to prevent deterioration from contact with soil and moisture, or degradation from fungi, insects, birds, and ultraviolet radiation. Common preservatives used include Creosote; Pentachlorophenol (penta); Chromated Copper Arsenate (CCA); Copper Naphthenate (CuN); 4,5-Dichloro-2-N-Octyl-4-Isothiazolin-3-One (DCOI); and Ammoniacal Copper Zinc Arsenate (ACZA).

[0006] Preservatives, however, create environmental hazards, as they can leach into soil and water.

[0007] Preservative treated wood disposal is also a challenging problem. Disposal has beyond a logistical challenge, increasing expense, while not fully mitigating the environmental impact of the infused preservatives. A study by the Electric Power Research Institute estimated that over 3 million wood utility poles are retired from service annually in the US. Retired Wood Pole Disposal and Reuse Options: Guidance for Final Pole Disposition. EPRI, Palo Alto, CA: 2017. 3002010815

[0008] It found that 78% of the utilities surveyed send end-of-life poles to landfills. Other disposal methods were incineration at waste to energy (WTE) or biomass facilities, with a smallportion of poles going to makers of recycled wood products. Utilities incur processing, transportation, and disposal or “tipping” charges when landfill disposal is employed, with poles taking up capacity in landfills and in many cases representing an ongoing liability due to the presence of preservative chemicals.

[0009] Many landfills will not take discarded poles due to liability concerns. Utilities have programs to give away used poles, generally required the recipient to sign legal disclaimers. These disclaimers assert that wood from the poles will not be used for certain uses such as residential construction or enclosed structures of any type.

[0010] While wood remains in most instances the most practical and cost-effective material for production of utility poles, there is a need for novel structural and material designs to reduce the reliance on wood infused with preservatives. Ideally, wooden utility poles would not only be constructed to eliminate preservatives but would also be designed to have increased strength and durability, and improved grounding properties. Increased resilience is needed in the electrical grid to prevent power outages and reduce repair costs resulting from high winds and lighting strikes.SUMMARY

[0011] The present design described herein (disclosure), for example, comprises a utility pole constructed with a lengthwise core of wood that is wrapped in fiberglass immersed in resin and then coated with an outer layer of material. This provides a utility pole having strength, rigidity and flexibility characteristics capable of bearing vertical, transverse, and other loading conditions and meeting the requirements for electric power distribution and other functions.

[0012] The disclosure also provides a means to eliminate the use of preservatives in the production of new wood-based poles.

[0013] The disclosure is not limited to poles used by electric utilities and telecommunications service providers but is also applicable to poles used as marine pilings, fence posts, and other structures.

[0014] The wood core of the present disclosure, for example, may be sourced from a discarded pole or a newly harvested and debarked tree. In one embodiment, the wood core is made from a newly harvested and debarked tree that has not been infused without preservatives. In another embodiment, the wood core is a previously used or discarded utility pole. The discarded pole is initially processed, for example, by removal of a portion of its outer layer of wood, thereby providing a clean surface for adherence of the wrapping and resin and removing some or all of the wood material containing preservative.

[0015] In one aspect of the disclosure, a process of simultaneous vacuum and microwave treatment is applied to remove moisture from the wood core, thus enabling the use of fiberglass wrapping without the risk of moisture outgassing from the wood over time. Such moisture outgassing would create pinholes where moisture can enter the structure and lead to wood deterioration and loss of integrity.

[0016] In another aspect of the disclosure, a grounding circuit is integrated into the finished pole. By integrating the grounding system into the structure of the pole itself, several benefits are provided to the utility or other pole owner, including reduced cost of installation time and labor, deterrence of copper theft, and improved dielectric grounding properties.

[0017] In other aspects of the disclosure, processes are provided for fabrication of poles where a wood core is wrapped in fiberglass or other composite material, and a specialty outer coating is applied.

[0018] It is to be understood that the foregoing general description and the following detailed description are both exemplary and intended to provide further explanation of the subject matter as claimed.BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings constitute a part of this specification and illustrate embodiments that, together with the specification, explain the subject matter. The present system is illustrated by way of example and not limited in the figures of the accompanying drawings in which like references indicate similar elements.

[0020] FIG. 1 is a cross-section view of a pole, according to one embodiment of the present disclosure.

[0021] FIG. 2 is a cutaway view of the pole, according to one embodiment of the present disclosure.

[0022] FIG. 3A and FIG. 3B are illustrations of a grounding system integrated into the structure of a pole, according to one embodiment of the present disclosure.

[0023] FIG. 4 is a flow chart illustrating a process for preparation of a discarded pole for reuse, according to one embodiment of the present disclosure.

[0024] FIG. 5 is a flow chart illustrating a manufacturing process for a pole, according to one embodiment of the present disclosure.DETAILED DESCRIPTION

[0025] The following detailed description is provided with reference to the figures. Exemplary embodiments are described to illustrate the disclosure, not to limit its scope, which is defined by the claims. One of ordinary skill in the art will recognize a number of equivalent variations in the description that follows without departing from the scope and spirit of the disclosure. All identically numbered reference characters correspond to each other so that a duplicative description of each reference character in the drawings may be omitted.

[0026] Utility poles of the present disclosure are constructed with a lengthwise core of wood that is wrapped in fiberglass immersed in resin and then coated with an outer layer of material. The wood core may be sourced from a newly harvested and debarked tree, or a discarded utility pole.

[0027] The pole may be used for other purposes, including marine piers, fence posts, or structural members of buildings. The poles may be of any length of which harvested trees are available. In one embodiment, poles are made in standard lengths such as 35 feet, 40 feet, 45 feet, 50 feet, or 55 feet. Tree diameter can vary but is typically in the range of nine to twenty- four inches for poles of these lengths.

[0028] FIG. 1 is a cross-section view of a pole, according to one embodiment of the present disclosure. In this embodiment, wood core [1] is wrapped in a resin-fiberglass layer [2] and an outer layer of coating [3] surrounds the resin-fiberglass layer. FIG. 2 is a cutaway view of a portion of a pole of the disclosure, according to one embodiment of the present disclosure. In this embodiment, wood core [1], layer of fiberglass wrapping [2], and outer coating [3] areillustrated. End caps cover each end of the pole. The outer coating [3] has indentations [4] providing textures for practical or aesthetic purpose.

[0029] In one aspect of the disclosure, a wood core [1] is used that is made from a newly harvested tree. The tree must be cut to length and debarked using means well known in the timber industry. Subsequently, the level of moisture in the wood core [1] must be reduced to prepare it for the resin-fiberglass wrapping process. Conventionally, harvested trees are dried naturally through allowing time to pass before further processing, or by placing them in a kiln.

[0030] In one aspect of the disclosure, a process for rapidly drying and dehumidifying the wood core [1] is utilized that employs a combination of vacuum and microwave irradiation. This process allows the rapid drying of the wood and achievement of a specific range of moisture content that is required for optimal adherence of wrapping material and prevention of outgassing during the heat setting of the resin-fiber. An additional advantage of this process is the elimination of microbial life within the wood that can result in later deterioration of the wood.

[0031] In the present disclosure, wood cores [1] are subjected to the above process for a period of time that results in a moisture level of from eight to twelve percent (8% - 12%) prior to further processing. Because wood is a highly porous material, moisture can readily travel through it. During heating of the wrapped wood core, moisture in the wood can vaporize and form microbubbles that move through the wood and surrounding wrapping to form tiny holes in the wrapping material. In the present disclosure, the specific level of dehumidification performed reduces the moisture content of the wood core to the point where this phenomenon of outgassing and pinhole formation is avoided. This process allows the use of a combination of fiberglass and wood materials described herein.

[0032] In the present disclosure, for example, the material wrapped around the wood core [1] can be any one of fiberglass mat, fiberglass cloth, aramid, carbon fiber, Kevlar, Dyneema, or other materials having strands of fiber. This material is infused or immersed in a matrix of resin containing a catalyst which, when activated, cures the resin and creates bonds with the fiberglass material and underlying wood core material. Resin utilized may be of any suitable polymeric formulation. The resin may be cured by one of several means, including heat activation, moisture activation, and UV light activation.

[0033] In one embodiment, for example, the resin used for fiber wrapping and in the exterior coating is derived from soybean or other vegetable sources.

[0034] In the present disclosure, for example, the outer coating [3] is composed of materials that include protectants against UV radiation, flame retardants, coloring, and polymeric resins that bond to the underlying resin-wrapping. The coating [3] is preferably a gel that can be applied in a gel form that later hardens to produce a solid coating that is bonded to the underlying matrix of resin and wrapping material.

[0035] The outer coating [3] can be textured or embossed and given specific coloring for aesthetic effect or purposes of safety.

[0036] Caps are placed on the ends of the pole to complete the entombment of the wood core [1] and provide protection against exterior conditions.

[0037] The combination of these two classes of material, wood and fiber composite, provides benefits in increasing the load bearing capacity as well as optimizing the degree of stiffness versus flexibility of the pole.

[0038] The present disclosure allows the use of wood material for production of utility poles while eliminating the negative environmental effects of wood preservatives. In addition, the ability to utilize recycled wood poles can materially reduce the waste stream from pole replacement. In addition, the wrapping and coating reduce potential for degradation or deterioration of the due to moisture or the action of insects, birds, fungi, and other organisms. In addition, the pole of the present disclosure provides a utility pole that reduces or avoids the environmental impact of the preservative infusion process in the production of wood poles, the higher carbon emissions resulting from the production of steel poles, concrete poles, or poles made entirely of composite materials.

[0039] In another aspect of the disclosure, for example, the wrapping [2] is applied in a non- uniform manner along the length of the pole. For example, utility poles intended for use in locations subject to tropical storms may have additional rounds of wrapping at the points most rupture during extreme wind conditions. In one embodiment, a pole is wrapped double or triple from the butt end to ten feet above ground.

[0040] In another aspect of the disclosure, for example, the wrapping [2] applied is made of material having greater resistance to tensional forces. For example, instead of the less expensive fiberglass wrapping a woven fiberglass material may be used for wrapping. In addition, additives can be mixed into the resin and / or into the exterior coating such as glass powder or carbon nanotubes. This produces a pole that can withstand more extreme forces and is therefore desirable for installation in locations that are subject to extreme winds or high levels of icing, or where survival of critical power and communications infrastructure is critical.

[0041] “When it comes to storm zones, which endure an estimated $54B in damages annually, the economic impact of downed poles is far greater than the cost of infrastructure replacement.Wide-scale grid failures impede the movement of manufactured goods leading to residual losses of critical food and pharmaceuticals. These outages immediately halt economic activity through loss of mass transit, traffic lights, power, and ventilation as well as cold storage.” Retired Wood Pole Disposal and Reuse Options: Guidance for Final Pole Disposition. EPRI, Palo Alto, CA: 2017. 3002010815

[0042] In another aspect of the disclosure, for example, a grounding system is integrated into the structure of the pole. FIG. 3A illustrates one embodiment of a grounding system of the disclosure. This grounding system is comprised of a conducting wire

[0010] that runs or travels through a conduit or sleeve

[0011] that extends through the entire length of the pole, said conducting wire connected to a grounding element

[0012] at the bottom of the pole. The sleeve is placed between the fiberglass wrap and the exterior coating of the pole. At the top of the pole, the conducting wire can be attached to a lightning collector element. The lightning collector element can take the form of numerous devices well known in the art. FIG. 3B illustrates this embodiment of a grounding system wherein a top view of the grounding element

[0012] is shown. In one embodiment of the disclosure, for example, the conduit surrounding the conducting wire is a fabric sleeve made from material with high-temperature resistance. This high-temperature sleeve may be made from heat-resistant materials such as E-glass fiberglass yarns, silica, or ceramic fibers, and acts as a heat barrier insulting against flash heat. A non-limiting example of this sleeve are the high temperature braided sleeve products produced by Techflex Inc. of Sparta, New Jersey.

[0043] The use of such material to surround the conducting wire acts to prevent combustion of the surrounding material in the event of a lightning strike.

[0044] The grounding element may be a metal plate attached to the bottom or butt end of the pole, or it may be a cap made of metal. Preferred metals for the bottom plate or pole cap serving as a grounding element include copper, bronze, and brass.

[0045] The grounding system of the present disclosure brings several benefits. This system eliminates the need for grounding stakes, which represent an additional expense, and require additional installation work for the bottom of the grounding wire running down the pole to be connected via an underground trench to the grounding stake. This grounding system also prevents the level of corrosion common with conventional utility pole grounding systems comprised of a wire running to the bottom of the pole that is then connected to the top of a grounding stake.

[0046] Another benefit of embedding the grounding wire within the pole is the deterrence of material theft. Theft of copper ground wires has become a widespread problem for utilities. In contrast with conventional grounding systems, where the conducting wire is stapled to the outside of a wooden pole, removal of the conducting wire from the integrated grounding system of the present disclosure would require a tremendous effort.

[0047] Another benefit of the grounding system of the present disclosure is that the conducting plate at the bottom of the pole ensures a low level of soil resistance. This results in a superior grounding performance making damage to the pole and equipment mounting on the pole less likely to be damaged in the event of a lightning strike.

[0048] In another aspect of the disclosure, for example, the wood core may be composed of a laminate material molded in a cylindrical shape. The materials for use in laminate may include bamboo and other wood types that provide high strength and attractive strength to weight ratios.

[0049] Next, exemplary production processes for pole structure(s) described herein are disclosed.

[0050] Aspects of the present disclosure include processes for production of utility and other pole types.

[0051] An example of product process utilizing end-of-life utility poles are described below.

[0052] In one aspect of the disclosure, discarded utility poles are used for the core of newly produced poles. FIG. 4 illustrates, according to one embodiment, the steps in the process of evaluating the suitability of individual discarded poles and, forthose found acceptance, preparing them for wrapping in fiberglass. A discarded pole is inspected for suitability

[0020] , Selected poles are then processed by cutting to length and removal of a portion of its outer layer of wood

[0021] , thereby providing a clean surface for adherence of the wrapping and resin and removing some or all of the wood material containing preservative. The process of removing an outer layer of material can be done using debarking equipment well known in the industry. Cut and shaven poles are then cleaned and measured

[0022] , Finally, the moisture content of these wood cores is reduced as needed before subsequent processing

[0023] ,

[0053] When discarded utility poles are utilized, the initial step is the selection of wood cores, which typically requires a visual assessment of exterior condition and an assessment of interior condition. The interior condition assessment may be done using ultrasound equipment, X-ray equipment, and invasive testing. Invasive testing can utilize resistomometer devices that drill a small diameter hole through the wood pole and measure the resistance at each point, allowing the condition of the wood to be inferred.

[0054] An additional step required when discarded utility poles are utilized, for example, is the detection and removal of any metal within the pole. This can be accomplished utilizing metal detection equipment. Any metal detected will be extracted or the pole will be rejected

[0055] The methodology to determine which individual poles are suitable for use, from among a supply of discarded poles, may be described as follows, in any order: (1) Elimination of poles that are too short or too curved; (2) Visual inspection and elimination of poles with substantial gashes, ruptures, or other severe damage; (3) Sound testing using a hammer test; (4) Inspection of poles by ultrasound and / or X-ray to detect deterioration or voids, e.g., this also detects any metal which needs to be removed; (5) Small diameter drilling to determine strength through a cross section of the pole and detect deterioration or voids; and (6) More extensive mini drill to more fully characterize pole quality and strength.

[0056] An example of product process utilizing newly harvested trees is described below.

[0057] In one aspect of the disclosure, a wood core is used that is made from a newly harvested tree. FIG. 5 is a flow chart illustrating steps in the process for production of a utility pole, according to embodiments of the present disclosure.

[0058] Prior to production, a tree must be cut to length and debarked using means well known in the timber industry. This provides a wooden core for the pole that will be produced in the process described herein. The initial step in the process is to reduce the level of moisture in the wood core to a level where it is prepared for the resin-fiberglass wrapping process

[0030] ,

[0059] Conventionally, harvested trees are dried naturally through allowing time to pass before further processing, or by placing them in a kiln. In one aspect of the disclosure, a process for rapidly drying and dehumidifying the wood core is utilized that employs a combination ofvacuum and microwave irradiation. This process allows for more rapid drying of the wood and achievement of a specific range of moisture content that is required for optimal adherence of wrapping material and target product quality, e.g., 5-15%, preferably 8-12%. The specific range may also depend on the materials used in the process. Another advantage of this process is the elimination of microbial life within the wood that might result in later deterioration of the wood.

[0060] Following dehumidification, cores are cleaned to remove dust or other matter from their exterior surface

[0031] , In the next process stage, a core is mounted on a jig and a taping machine rotates around the core wrapping the fiberglass material and moving longitudinally along the length of the core

[0032] , The wooden core acts as mandrel for wrapping fiber material. In an alternative approach the core can be rotated during this stage of the production process. Fiberglass or other wrapping material is immersed or submersed in a resin bath prior to being fed into the taping machine.

[0061] The taping machine, for example, moves longitudinally along the wooden core so that the entire core is covered with one or more layers of wrapping material. In one aspect of the invention, specific areas of the core receive an additional layer or additional layers of wrapping to provide greater strength to those portions of the pole. In some embodiments, wrapping materials of high strength, such as Kevlar, are used for wrapping to produce poles that can withstand extraordinary forces such as hurricane winds or vehicle impacts.

[0062] Next, the newly wrapped pole is cured using well known techniques such as heat curing, moisture curing, or radiation curing

[0033] ,

[0063] Following this, a coating of gel material is applied to the exterior of the in-process product

[0034] , In one embodiment, spray guns are used for this application. In the production ofany particular unit or batch of units, the coating mix may be altered to meet specific product requirements. Constituents of the coating that may be varied include, for example, colorants, flame retardants of different qualities, resin of differing qualities, and UV protectants. Any number of combinations may be utilized to meet the requirements of different geographic locations and end uses for the poles. The newly coated pole then undergoes a curing process where the coating and underlying resin-soaked wrapping undergo bonding.

[0064] Following, this the coating pole undergoes surface patterning

[0035] , This can be done by embossing, stamping, or similar techniques. In one embodiment, for example, silicon molds are used to provide patterns. Patterns can vary to provide any number of surface textures, from smooth, to textures simulating wood grain to geometric patterns.

[0065] The final steps in production process may be attachment of the end caps

[0036] and labeling of the pole

[0037] , The top and bottom end caps can be made of varied materials designed to provide a protective barrier to seal the wood core from moisture. The top end caps may be composed of plastic or other non-conductive material, while the bottom cap may be composed of plastic, fiberglass, or other material, designed to provide a protective barrier and a surface for attaching a metal grounding plate. Alternatively, the bottom cap may be composed of conductive metal, thereby functioning as a protective barrier and grounding plate.

[0066] The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present subject matter. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the subject matter. Thus, the present subject matter is not intended to be limited to theembodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0067] While various aspects and embodiments have been disclosed, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed are for purposes of illustration and are not intended to be limiting. Those skilled in the art will recognize that modifications and variations can be made without departing from the scope and spirit of the invention, as defined, for example, by the appended claims.

Claims

POLE-OOl -PCTCLAIMS1. A pole comprising: a wood core; a fiberglass layer surrounding the wood core; and an outer coating layer surrounding the fiberglass layer, the outer coating layer comprising a polymeric material, wherein the wood core has a moisture content between 8-12% prior to the application of the fiberglass layer.

2. The pole of claim 1, wherein the fiberglass layer comprises fiberglass material embedded in a resin matrix.

3. The pole of claim 1, wherein the outer coating comprises a surface texture.

4. The pole of claim 1, wherein the wood core is derived from a previously used utility pole that has been processed to remove surface contaminants and preservative-treated layers.

5. The pole of claim 1, wherein the fiberglass material is selected from the group consisting of fiberglass mat and fiberglass cloth.

6. The pole of claim 1, further comprising end caps attached to the top and bottom ends of the pole.

7. The pole of claim 1, wherein the fiberglass layer has a non-uniform thickness along a length of the pole.

8. The pole of claim 1, wherein the outer coating comprises additives selected from the group consisting of UV stabilizers, flame retardants, and colorants.

9. The pole of claim 1, wherein the outer coating comprises a hardened polymeric layer formed from a gel material.

10. The pole of claim 1, wherein the wood core is substantially free of microbial life.

11. The pole of claim 1 , wherein the pole is configured for use as a utility pole, marine pier, fence post, or structural member of a building.

12. The pole of claim 1, further comprising a grounding system comprising: a conducting wire extending along the length of the pole; a conduit surrounding the conducting wire; and a grounding element electrically connected to the conducting wire at a bottom end of the pole.

13. The pole of claim 12, wherein the conduit is positioned between the fiberglass layer and the outer coating.

14. The pole of claim 12, wherein the conducting wire is embedded within the pole in a manner that inhibits theft and corrosion.

15. The pole of claim 12, wherein the grounding system comprises an integrated grounding element configured to provide electrical grounding without the use of external grounding stakes.

16. A method of manufacturing a pole comprising: providing a wood core; reducing the moisture content of the wood core to between 8% and 12%; wrapping the wood core with a fiberglass material; and applying an outer coating over the fiberglass material.

17. The method of claim 1, wherein the moisture content of the wood core is reduced using a process comprising vacuum and microwave irradiation.

18. The method of claim 1, wherein the fiberglass material is embedded in a resin matrix prior to wrapping the wood core.

19. The method of claim 1, wherein the outer coating is applied in gel form and subsequently cured to form a hardened layer.

20. The method of claim 1, further comprising attaching end caps to the top and bottom ends of the pole.

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