Patent Application
20170198855
The invention of this application relates to electrically conductive joints for metallic pipelines and, more particularly, to create electrical conductivity between and among joints by use of an intrinsically conductive gasket arrangement for the joints in metallic pipes that are buried or submerged pipelines that are generally made of ductile iron, cast iron and/or steel. These metallic pipes are coupled together by mechanical means to the create pipelines. The invention also relates to a method of using the same.
The invention of this application relates to electrical conductivity between and among joints for metallic pipelines and, more particularly, to create such conductivity by the use of intrinsically conduct gaskets for the joints in metallic pipes that are buried or submerged as pipelines and most often made of ductile iron, cast iron and/or steel. However, this pipes can also be made from copper, aluminum, and stainless steel. These metallic pipes are coupled together by mechanical means to create pipelines. The invention also relates to a method of using the same. The AWWA Standard C111/A21.11-07 relates to Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings and is incorporated by reference for showing the same and forms part of the specification of this application.
Cast and, more recently, ductile iron pipe have been used extensively for underground waterlines since the 1800's. It was thought that such material would last 50 to 100 years or more because of its corrosion tolerance due to the relatively thick pipe walls. In fact, there are iron pipelines that have lasted well over 100 years. However, where the iron pipe is installed in relatively aggressive environments, failures have been reported to have occurred in 10 or less years, most often due to galvanic or electrolytic corrosion. When the pipe fails, its operator is most often left with only the option to replace large sections of pipe in fear that the location of failure was a precursor to further, more extensive failures. However, many times it is later discovered that only a small length of the pipeline is in need of replacement. And, this failure of only a small length of pipeline can result in significant repair costs.
Currently, it is common practice in the water industry to install polymer gaskets, usually of synthetic rubber, where pipe sections are joined to prevent weeping or leaking of the fluids being carried by the pipe. The current gasket designs are generally effective in providing such a seal between the pipeline joints. However, because conventional gaskets are made of materials that are dielectric, adjacent pipe sections are rendered electrically discontinuous or isolated. Therefore, any electrical current that intentionally or unintentionally travels down a buried or submerged pipeline must conduct, or jump, from one pipe, into the soil and then back onto an adjacent pipe in order to continuously continue down a pipeline to the source of the electric current. In the case of direct current (DC) on a steel pipeline, approximately twenty (20) pounds of metal will be removed by way of corrosion for each year that one (1) ampere of DC current discharges into the electrolyte (soil or water). This becomes a particular problem when a pipeline is buried in the proximity of mines that operate using DC powered equipment or, more likely, near rail transit systems that use DC powered motors. In the case of the transit system that uses one of its rails as the return path to the source of the power that runs the train's motor, experience has proven that a certain amount of current flows into the soil and on to adjacent metal structures, including underground pipelines. This is because electrical current will take all paths of resistance in proportion to their relative conductivity. Simply put, Ohms Law [I Current (amperes)=V (Volts)/R (Resistance)] defines the amount of current that will flow through an electrical circuit. Therefore, where current leaks into the ground, some finds its way onto underground pipelines and usually causes the pipeline to fail due to corrosion if left unabated. Further, in view of lower installation costs, it may be desirable to install pipelines in close proximity to rail transit systems in that the path cut for the rail system is likely cleared of foliage and buildings and thus allows for easier and much less expensive construction for the pipeline. This increases the likelihood that the pipeline will pick up current leaked into the ground from the transit system resulting in vastly premature failure of the pipeline.
When the electrical current moves onto the surface of a pipeline, it will travel along the pipe and will follow the path to return to the stray current power source in proportion to its paths of resistance. As it travels along the pipeline, it will eventually arrive at a mechanical joint between adjacent pipes. If the mechanical joint allows the current to pass to the adjacent pipe via intentional or inadvertent electrical continuity, it will continue through the mechanical joint with little or no damage to the pipeline. Metal-to-metal current flow is “electronic” current flow and this type of current flow does not cause corrosion. However, if the mechanical joint does not allow the current to freely pass to the adjacent pipeline by metal-to-metal contact, the current must take a different path; again based on the proportional paths of least resistance. If a traditional gasket is used in the mechanical joint, the current must travel (jump) through the soil and return to the adjacent pipe due to the extremely high electrical resistance of the elastomeric gasket. Transfer from metal to water or moisture in soil current flow is “electrolytic” current flow and electrolytic current flow or conductance causes corrosion on the pipeline surface. Again, where one (1) ampere of DC current discharges from a steel pipe for a year from electrolytic current conductance, it takes with it approximately twenty (20) pounds of metal. This is what is commonly called “stray current,” “electrolysis” or “electrolytic” corrosion as it is caused by the presence of some external source of DC electricity usually caused by adjacent DC powered equipment such as those used in mines, impressed current cathodic protection systems and, most often, transit systems on rails. If the pipeline is electrically continuous along its length, the current can be drained back to its source by a single electronic bond, thus minimizing or eliminating highly damaging corrosion of the pipeline from electrolytic current conductance. Attempts to weld metal jumper bonds across the pipe joints to establish the necessary electrical continuity have often proven costly and subject to contractor error or post-installation electrical bond material failure.
All metals are subject to a natural oxidation process that follows the laws of nature, which occurs when a metal is in contact with an electrolyte. The electrolyte is normally the water in which the pipe is submerged or moisture in the soil in contact with a buried pipeline. A highly cost effective means of mitigating corrosion on buried pipelines is an electrical process called cathodic protection, which overcomes the natural tendency of a metal to corrode. Often, the most effective and economical means of providing cathodic protection to a pipeline is to impress DC current from a buried electrode (anode) through the soil or water onto the pipe thus overcoming the pipe's tendency to corrode by discharging current. However, for an impressed current cathodic protection system to operate effectively, the pipe must be electrically continuous along its length. If the pipe is not electrically continuous along its entire length, then attempts to use cathodic protection in a pipeline can have the same detrimental corrosion effect as stray current. As is known in the art, if the “electrolysis,” “stray current” or “electrolytic” corrosion is allowed to continue, corrosion-induced holes in the pipeline will eventually form. And, if these holes are not repaired, the pipeline will form leaks.
In view of the significant costs associated with pipe replacement resulting from “electrolysis” or “electrolytic” corrosion, it is commonly understood that the most effective time to establish continuity of a buried pipeline is during pipeline installation. However, prior attempts to establish continuity of a buried pipeline have been found to be costly and often ineffective. Further, some prior attempts have been found to create corrosion points in view of the creation of electrical arc points and from the use of dissimilar materials to create the bonds. An arc point is the relatively high-resistant contact point between the metal bonding component(s) and the pipes in the pipeline. When most or all of the current traveling between adjacent pipes in the pipeline travels by way of a small current path (either in number or size) in the metal bonding component(s), the relatively high circuit resistance can make the metal component(s) heat up in the presence of high current much like a high resistance wire. The heat can then damage the metal component(s) and materials around the component, such as the rubber in the gasket. And, ultimately can become so highly resistant at the metal to pipe boundary that it will create an electrical arc. Because of the relatively high resistance between the metal bonding component and the pipe, this electrical arc can then “jump” to adjacent materials, which includes jumping to the surrounding soil. Moreover, it has been found that when these current paths heat up and arc, these current paths then became non-conductive thereby worsening the jumping of current into the soil.
One such attempt has been the use of insulated jumper wires or straps that are welded or bolted across the mechanical joints. This process is labor intensive and subject to failure for multiple reasons. As can be appreciated, this method creates an extra step for the completion of every mechanical joint in the pipeline. In that there can be thousands of mechanical joints on a single pipeline, this can add significant cost to the overall cost of the project. As can be further appreciated, in view of the added cost associated with the addition of the jumper wires or straps, common practice is to install only one jumper wire or strap at each pipe joint. And, if this single jumper strap fails when stray DC currents are impressed onto the pipe, the pipe will eventually fail due to accelerated corrosion at or near the discontinuous pipe joints and need to be replaced. Yet further, jumper straps failure can be caused in several ways. First, the jumper wire could be defective initially in view of contractor error during its installation to the pipes. As can be appreciated, when thousands of jumper wires are manually welded or bolted along a pipeline, there is an unacceptably high chance that one or more will be installed improperly. And, it takes only one improper installation to break the electronic current flow path across the pipeline joint(s). Second, the jumper wire must be welded or bolted to an outer surface of the pipes wherein there is also a risk of mechanical damage to the jumper wire and/or jumper wire during installation of the pipeline and/or the backfilling of the pipe trench. As can be also appreciated, the jobsites for pipeline installation can be in harsh environments with large equipment and the movement of tons of dirt and gravel to dig and then backfill the pipe trench. Third, the use of welded bond apparatus, and even bolts, can add dissimilar materials to the pipeline when the wire itself, the welding materials and/or the bolts are dissimilar to the iron pipe, which will then create its own form of galvanic corrosion. Fourth, since only a single jumper wire is typically used that can create a current arc point if not installed properly. In that a current arc point is created, it can increase the likelihood that the jumper wires or straps will fail. All current that is impressed on the pipeline must return to its source, often miles away. This is of particular concern if a single bond fails. The corrosion at the electrical arc point created by this failure will concentrate corrosion at that location, especially if all other bonds remain intact and effective.
In view of the inherent problems with bonding pipe joints with jumper wires or straps, other prior art attempts to solve this problem have included gaskets that include adding one or more mechanical, metallic components with the intent of creating metallic current flow paths to the gasket material. Thus, the gasket itself was intended to include one or more current flow paths to electronically conduct electrical current between adjacent pipe sections. These components have included one or more electrically conductive metal components to provide the electrical connection between the adjacent pipes. These can come in the form of metal particles, wedges, tabs, wire or mesh. However, these have not provided an effective outcome. First, in that the gasket is a hidden component, it is difficult to determine for sure if the mechanical current flow components are making effective contact with both pipes. If there is a lack of metal-to-metal contact through the gasket to both adjacent pipes, the current flow path will likely be insufficient to provide the needed electronic conductance. Even when these conductive-metal loaded gaskets provide some measure of electronic conductance, low electronic conductance can result in the lowest or a proportionally more significant path of electrical conductance being the surrounding soil wherein the DC current will still jump into the soil and travel back to the adjacent pipe. Second, the mechanical current flow paths can create a leak point if they prevent the elastomeric material from sufficiently engaging both pipe sections. As can be appreciated, a less aggressive mechanical flow path(s) may not be sufficient to make the needed electronic electrical connection between adjacent pipes if it is urged or buried below the elastomeric gasket's surface, while an overly aggressive mechanical flow path that extends beyond the elastomeric gasket's surface can prevent a good seal. And, the number of mechanical current flow paths must be weighed in view of this tradeoff between a good seal and good conductivity. Third, mechanical flow paths in the gasket can create the current flow arc points noted above. And, it has been found that these mechanical current flow paths can heat up, arc and then became non-conductive. Yet further, these arc points create heat that can damage the rubber in the gasket and create additional leaks. And, even if multiple mechanical paths are created, there is always the possibility that less than all of them will make electrical contact between the adjacent pipe sections. As a result of these shortcomings, significant pipe corrosion and premature pipe failure results, especially when the pipe was installed in relatively low resistivity soils.
Accordingly, past attempts to create conductive mechanical joint devices have been ineffective wherein there remains a need in this industry for a solution to this problem. In this respect, even with these prior designs it is reported that 6 billion gallons of potable water are “unaccounted for” daily in the United States alone and that this is primarily due to leaks. And, that it is understood in this industry that many or most of these leaks are due to corrosion. Moreover, even though the loss of billions of gallons of water is very expensive and it is also very expensive to fix these leaks after installation, there is still no adequate solution to this problem in the industry. Accordingly, there is a significant need in the industry to reduce “electrolysis,” “stray current” or “electrolytic” corrosion through effective electrical bonding of mechanical joints and prior attempts have been ineffective.
The invention of this application relates to a mechanical joint between adjacent buried pipes that prevents stray current from exiting the pipeline into the surrounding soil or water while still providing an effective seal between the pipeline joints. More particularly, the invention relates to a gasket arrangement that has non-mechanical, electronic current flow paths wherein the gasket itself is intrinsically conductive and; more particularly, to an intrinsically conduct gasket for metallic pipes that are buried or submerged as pipelines and made of ductile iron, cast iron and/or steel. These metallic pipes are coupled together by the mechanical joint to create pipelines.
More particularly, the invention of this application relates to a mechanical joint that can establish electrical continuity along long runs of ductile or cast iron pipelines as a part of a properly engineered pipeline life extension program. Moreover, the mechanical joint provides electrical continuity about substantially all of the annular contact surface between adjacent pipes, which reduces ineffective conductivity and electrical arc points.
According to certain aspects of the invention, provided is an intrinsically conductive polymer to form a gasket primarily intended for use on bell and spigot (push-on joint assembly) pipes.
According to another set of aspects of the invention, provided is intrinsically conductive polymer gaskets generally in range of between 3 inches and 84 inches in diameter.
According to another aspect of the invention, the compound resistivity of the mechanical joint of this application can be varied and then held consistent for each individual pipeline project. Thus, the life extension in years between a pipeline using the invention of this application and one using prior, practically non-conductive technology can be calculated during the pipeline design phase. The ability to vary the compound resistivity provides significant flexibility to the pipeline design engineer. In this respect, varied compound resistivity, which is not available in the prior art, allows specification of the gasket of this application for compatibility with project specific factors, such as measured and anticipated stray DC earth current variables. Moreover, varied compound resistivity allows the pipeline engineer to design capabilities over the gasket conductance, which otherwise would be an uncontrollable pipeline operating variable. As a result, added pipeline life expectancy due to stray DC current mitigation can be established during the design phase of the pipeline with a much increased level of confidence. Moreover, pipeline life expectancy is significantly increased.
According to yet other aspects of the invention, provided is a mechanical joint that can also be used for cathodic protection systems.
According to further aspects of the invention, provided is a method of protecting from corrosion of a pipeline by providing a conductive mechanical joint between adjacent buried pipes that prevents stray current from exiting the pipeline thereby preventing corrosion-induced holes from forming in the pipeline while still providing an effective seal between the pipeline joints.
According to certain aspects of this method, this is achieved by providing a mechanical joint that includes a gasket arrangement that has non-mechanical, nearly continuous electronic current flow paths wherein the gasket itself is intrinsically conductive.
More particularly, the invention of this application relates to a mechanical joint that can establish electrical continuity along long runs of ductile or cast iron pipelines as a part of a properly engineered pipeline life extension program. Moreover, the mechanical joint provides electrical continuity about substantially all of the annular contact surface between adjacent pipes, which reduces ineffective conductivity and electrical arc points.
According to certain aspects of the invention, provided is a method of using an intrinsically conductive polymer to form a gasket primarily intended for use on bell and spigot (push-on joint assembly) pipes and to allow a free flow of electrical current through the pipeline without current jumping through the soil between adjacent pipes.
These and other objects, aspects, features and advantages of the invention will become apparent to those skilled in the art upon a reading of the Detailed Description of the invention set forth below taken together with the drawings which will be described in the next section.
The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which form a part hereof and wherein:
Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting the same,
Pipeline 10 is a buried pipeline that can be made of ductile iron, cast iron and/or steel. These metallic pipes 20 are coupled together by mechanical joints 30 to create pipeline 10 and to allow a flow of liquid L, typically potable water, from first extent 12 to second extent 14. As can be appreciated, any pipeline configuration could be a part of the invention of this application wherein
The invention of this application relates to mechanical joints 30 between adjacent buried pipes, and methods relating to these mechanical joints that have been found to significantly increase the expected lifespan of the pipes in the pipeline without adversely creating leaks. In particular, the invention of this application has been found to significantly reduce the effects of a stray current SC on pipeline 10. As is shown in
With special reference to
With special reference to
While prior art devices have attempted to control the flow of stray current SC, it has been found that many of the systems used have been ineffective and that these prior art system create their own problems.
The invention of this application relates to a pipeline 10 that includes a gasket arrangement 40 that both provides excellent sealing qualities, but which also provides non-mechanical internal current flow paths 42 that extend about essentially all of the annular gasket between adjacent pipes. By having non-mechanical electrical flow paths 42 wherein the gasket itself is intrinsically conductive, there are no current arc points created and there are no fluid leak points created. DC current on the pipeline will flow substantially from one pipe to the next through the gasket itself and there are no leak points produced from current jumping into the soil. Further, by having a gasket that is intrinsically conductive, current can flow about the entire joint wherein at least some of the gasket will provide current flow paths 42 even if a portion of the gasket is damaged. Yet even further, by allowing the stray current flow to be more evenly distributed about the entire gasket, the stray current is less likely to jump from the pipe into the soil regardless of the soil resistivity. Even yet further, the use of intrinsically conductive gasket material for gasket 50 allows gasket 50 to use any of the existing dimensional gasket designs that are used in the industry today without the need to re-tool pipes 20 of pipeline 10, some of which will be described more below. Again, it must be noted that the description of this application is intended to be descriptive and not limiting wherein some, but not all, of the existing joint designs are described herein. However, the invention of this application is not to be limited to these particular designs wherein it can be used in any buried or submerged pipe design currently known and/or which will be discovered in the future.
In greater detail, and with reference particular reference to
Gasket 50 can further include a lead in taper 70 that allows the joint to be pushed together as is shown in
Gasket 50 includes an intrinsically conductive polymer 92 so that the some or all of the gasket can act as an electric conductor wherein it forms flow paths 42 therein. As a result, any stray current SC in pipe section 20d would pass freely to pipe section 20c about at least a large portion of the gasket wherein flow paths 42 freely direct any stray current SC between sealing and electrical engagement surfaces 62 and 66, which provides a widely dispersed current flow within polymer 92. In fact, the electrical connection between the adjacent pipe sections would be transferred through a substantial portion of contact surfaces 62 and 66 by the engage between the contact surfaces and the corresponding pipe surfaces. Accordingly, there is no individual point contact for the electrical conductivity, there are no arc points, the electrical conductivity can take place about any circumferential point of the gasket arrangement and damage to a portion of the gasket is less likely to eliminate the electrical conductivity between adjacent pipe sections. Yet further, by providing dispersed current flow about a substantial portion of the annular gasket, smaller current will be present at any one location about the mechanical joint thereby reducing arc points and reducing the likelihood of a current jump at the joint.
As will be discussed more below, the electrical conductivity of gasket 50 can be determined and/or modified by local conditions such as the type of potential stray current and the soil resistivity. While a traditional gasket typically has a resistivity of over 5,000 ohm-cm, gasket 50 can ideally include a resistivity below 100 ohm-cm. In a preferred set of embodiments, gasket 50 includes a resistivity in the range of 1 to 700 ohm-cm. More preferably, gasket 50 includes a resistivity in the range of 1 to 550 ohm-cm. Even more preferably, gasket 50 includes a resistivity in the range of 1 to 400 ohm-cm. Yet even more preferably, gasket 50 includes a resistivity in the range of 1 to 200 ohm-cm. Even yet more preferably, gasket 50 includes a resistivity in the range of 1 to 100 ohm-cm. in the embodiments shown, gasket 50 includes a resistivity of about 70 ohm-cm.
With reference to Table I below, shown is the Life Extension Multiple that has been found for the gasket arrangements of this application. The Life Extension Multiple is the amount of times longer a pipe in a pipeline would last with the invention of this application as compare to a prior art polymer gasket that has a resistivity of about 5,390 ohm-cm. In this respect, a Life Extension Multiple of 2 would mean that a buried pipe utilizing the gasket of this application would last twice as long as a pipe with a prior art polymer gasket. A Life Extension Multiple of 4 would mean that a buried pipe utilizing the gasket of this application would last four times as long as a pipe with a prior art polymer gasket. In Table 1, this Life Extension Multiple has been calculated based on the preferred embodiments wherein material 92 has a resistivity of 75 ohm-cm in gasket 50 and is installed in soil having a resistivity of 10,000; 100,000; and 1,000,000. It has been found that a gasket 50 having material 92 with a resistivity of 75 ohm-cm can provide seventy times the life expectancy in the presence of 10 amperes of continuous DC current. In greater detail, if soil S has a soil resistivity of 10,000 ohm-cm, gasket 50 would have a Life Expectancy Multiple of forty-seven wherein it would last forty seven times as long as a prior art polymer gasket. If gasket 50 is used in a pipeline that is buried in soil S having a soil resistivity of 100,000 ohm-cm, the Life Expectancy Multiple is sixty eight times that of a prior art polymer gasket. If gasket 50 is used in a pipeline that is buried in soil S having a resistivity of 1,000,000 ohm-cm, the Life Expectancy Multiple is seventy one times that of a prior art polymer gasket.
As can been seen from Table I above, gasket 50 according to the invention of this application can drastically increase the life of one or more of the pipes 20 in the pipeline. It has been found that a gasket 50 having material 92 with an electrical resistivity of less than 550 ohm-cm will provide a Life Extension Multiple of at least ten (ie: pipes 20 would last at least ten times as long) as compared to conventional polymer gaskets with a constant electrical resistivity of 5,390 ohm-cm for most soil types. A gasket 50 having an electrical resistivity of less than 75 ohm-cm can increase pipe life by up to seventy times as compared to conventional polymer gaskets.
Further, and with reference to the table below, it has also been found that the advantageous properties described above can also be achieved with a gasket that also meets the ANSI Specification wherein the gasket further has the properties of Table II below and which can be formed into currently utilized gasket configurations. Yet further, this can include intrinsically conductive polymer 92 being used in inner sealing and electrical engagement surfaces 62, outer sealing and electrical engagement surfaces 66 and extending therebetween to produce a conductive portion or region 96 of gasket 50. This region can be purely a more conductive region and/or a better sealing region for the gasket seal and can be separate form a more structural region 98 that can be produced by a different material, such as being produced with a higher durometer material in accordance with certain portion of the ANSI Specification.
†Of original values of tensile and ultimate elogation.
‡Oxygen pressure method; after 96 hr at 70° C. ± 1° is 500 psi ± 10 (2,068 kPa ± 69).
§After a minimum of 25-hr exposure in 50-pphm more concentration at 104° F. (40° C.) on a loop-mounted gasket with approximately 20 percent elongation at outer surface.
Gasket 50 can be designed and used in a wide range of pipe systems including, but not limited to, a wide range of bell and spigot (push-on joint assembly) pipes as is described above. Further, gasket 50 can be made in a wide arrange of gasket configurations (existing and new) without detracting from the invention of this application, which is best shown in
According to another important aspect of the invention, by removing the mechanical electrical connectors and utilizing an intrinsically conductive compound for gasket 50, the compound resistivity of flow paths 42 in the gasket of this application also can be varied based any variable relating to the pipeline. As discussed above, the resistivity can be varied and held to a wide range of values and these can be set based any factors relating to the environment that the pipeline will travers. Yet even further, the gaskets of a pipeline even can have different properties within different sections of the pipeline as the pipeline passes through different soil types and different levels of potential stray current, which was not heretofore possible. Then, once a preferred compound resistivity is determined (either for the pipeline or a section of the pipeline), it can be held consistent for each individual pipeline project and/or section of the pipeline project. Thus, the life extension in years between a pipeline using the invention of this application and one using prior technology can be calculated during the pipeline design phase. The ability to vary the gasket compound resistivity provides significant flexibility to the pipeline design engineer. In this respect, varied compound resistivity, which is not available in the prior art, allows specification of the gasket of this application for compatibility with project specific factors, such as stray DC earth current variables. Moreover, varied compound resistivity allows the pipeline engineer to design capabilities over the gasket conductance, which otherwise would be an uncontrollable pipeline operating variable. As a result, pipeline life expectancy can be established during the design phase of the pipeline with a much increased level of confidence since electrical bond wire or strap installation error or defect is virtually eliminated. Moreover, pipeline life expectancy is significantly increased.
As can be appreciated, mechanical joint 30 of this application also can be used in connection with cathodic protection systems. Moreover, the benefits of the dispersed current flow of the gasket will also benefit the current flow in the cathodic protection system.
Accordingly, the mechanical joint of this application can be used as a method of protecting a pipeline by both providing an electrically conductive mechanical joint between adjacent buried pipes, by providing the needed sealing qualities between the pipe sections and by providing the needed current passage between adjacent pipe section in a single component of the mechanical joint between adjacent pipes. Further, damage to the conductive gasket is unlikely since it looks and is installed exactly as the prior art gaskets which pipeline contractors have employed for decades. And, the mechanical joint is less likely to reduce any of these qualities in view of the non-mechanical dispersed current flow about substantially all of the gasket and not just spaced mechanical current flow devices.
With reference to
y=(15.17*ln(x))+20.95
where:
The life extension formula is derived from comparing the predicted life of a pipeline using a standard gasket to one using arrangement 40, which are calculated from the following formula:
Corrosion Life=(Rsoil/(Rtotal)*I*A*D*CR*T
where:
The graph of
It must be noted that although the installation of invention of this application can further increase the life of a buried pipe due to resultant mitigation of long-line, naturally occurring galvanic corrosion cells, such benefit is not included in the mathematical models described herein.
The invention of this application utilizes an intrinsically conductive polymer 92 to at least partially produce gasket 50 wherein the preferred polymeric compound is sufficiently conductive to allow the vast majority of any electrical current on the pipeline to travel electronically across the adjacent pipe joints through flow paths 42 within the gasket material itself rather than electrolytically between the adjacent pipe joints by jumping through the surrounding soil. In particular, and with special reference to
According to other embodiments of the invention, provided is a method of installing an underground pipeline including the steps of:
Providing gasket 50 that is formed by an intrinsically conductive polymer 92 to form a gasket having at least a portion of the gasket including internal flow paths 42 wherein the gasket is primarily intended for use on bell and spigot (push-on joint assembly) pipes and to allow a free flow of electrical current through the pipeline without current jumping between adjacent pipes. The gasket dimensions being in accordance with the manufacturer's standard design dimensions and tolerances. The gasket being of a size and shape to provide an adequate compressive force against the plain end and socket after assembly to effect a positive seal under all combinations of joint and gasket tolerances and which provides the needed engagements between sealing and electrical engagement surfaces 62 and 66 and the corresponding pipes;
Cleaning the groove and the bell socket of pipe 20c;
Cleaning the plain end of mating pipe 20d.
Inserting gasket 50 into the bell end of pipe 20c;
Installing gasket 50 into the bell socket of pipe 20c, making sure the gasket faces the correct direction and that it is properly seated in the groove of bell socket of pipe 20c:
Apply lubricant 90 to exposed and sealing surface 62 of gasket 50 in accordance with the pipe manufacturer's recommendations;
Beveling pipe end 82 of pipe 20d as needed per the manufacturer's recommendations to form bevel or lead in 84;
Pushing plain end 82 of pipe 20d into the bell end 80 of pipe 20c keeping the joint straight while pushing.
Making any needed deflection after the joint is assembled.
While small pipes can be pushed into the bell socket with a long bar. Larger pipes can requires additional power, such as a jack, lever puller, or backhoe.
The method described above can further include providing a gasket 50 that includes a resistivity in the range of 1 to 700 ohm-cm. More preferably, gasket 50 includes a resistivity in the range of 1 to 550 ohm-cm. Even more preferably, gasket 50 includes a resistivity in the range of 1 to 200 ohm-cm. Even yet more preferably, gasket 50 includes a resistivity in the range of 1 to 100 ohm-cm.
Yet even further, it has been found that the gasket of this application can be manufactured using existing or manufacturing techniques not yet realized in this industry. As is referenced above, the gasket of this application can be used in connection with a wide range of pipe sizes. These can include traditional sizes (and others) that are in the range of 3 inches to 84 inches in diameter. And, while many of these gaskets have a different diameter, they may include the same cross-sectional configuration and examples of these cross-sectional configurations are shown in
While considerable emphasis has been placed on the preferred embodiments of the invention illustrated and described herein, it will be appreciated that other embodiments, and equivalences thereof, can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. Furthermore, the embodiments described above can be combined to form yet other embodiments of the invention of this application. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
This application claims priority to provisional patent application Ser. No. 62/278,240 filed on Jan. 13, 2016, which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62278240 | Jan 2016 | US |
