Pipe Repair System

FIELD OF THE INVENTION

[0001 ] The present invention relates generally to a system for repairing damaged High-density Polyethylene (HDPE) pipe.

BACKGROUND

[0002] Polymer pipes, and in particular High-density Polyethylene (HDPE) pipes, are very popular for domestic, mining, industrial and irrigation applications, and often provide advantages over alternative piping solutions such as iron, steel or cement pipes. For example, HDPE pipes are commonly used for both above and below ground pipelines, including pressurised water or gas supply pipe applications, and for sewerage pipe applications.

[0003] During the operational life of a HDPE pipe, there is often a need to conduct repairs on the pipe itself due to pipe integrity issues. Such issues can be caused by, for example, UV deterioration, wall thickness loss due to internal erosion through propellant solids, external damage via third party interventions, or through pipe vibration or movement during backfill operations, during which protruding stones or other materials can damage the pipe wall.

[0004] While steel pipes can be repaired using composite wraps to retain pipe integrity, composite wraps have generally not been used on HDPE pipes dues to their inability to adhere or bond effectively to the HDPE pipe, which is often due to material disparities between the HDPE pipe and composite wraps.

[0005] Therefore, mechanical means have been more widely used for repairing HDPE pipe. To function effectively, such mechanical means, often involving bolted repair clamps, usually require a heavier grade pipe with a larger wall thickness. This enables the pipe to remain rigid as the clamp forms around the pipe in compression, as a form of repair, thereby alleviating the hoop stress induced by the pressure of fluid transiting through the HDPE pipe. However, such mechanical means often cannot adequately reduce longitudinal stresses along the pipe. Furthermore, lighter pipes, with thinner walls, have an increased risk of deformation under compression where mechanical clamps are used. In addition, bolted mechanical clamps have tendencies to become relaxed over time due to loosening of bolts as the pipe contracts and expands with varying pressure and temperature cycles.

[0006] Further, mechanical repairs, while commonly used on straight pipe, cannot be applied to bends, T junctions, welded pipe saddles or welded jointing couplers. More complex repairs, such as saddle electrofusion repairs require substantial heating to be fused to HDPE pipes to increase wall thickness and thereby increase their integrity. This type of fitting is however problematic, especially when the defect wall loss is significant. The heat used to weld the saddle to the pipe can also burn through the pipe resulting in pipe failure and loss of pipe product.

[0007] Defects are normally detected by visual recognition where the pipe has visually been scratched, gouged and/or squashed during transportation, installation or excavation. When a defect has been located, the method of repair is usually selected on location and depends on the type of defect, size and risk profile associated with a pipe rupture. The operator typically considers the pipeline downtime and commercial evaluation of the repair. Some operators must close production plants to conduct a repair, which can be expensive, so repair options must be considered carefully.

[0008] Operators may isolate a section of leaking pipe and cut out the leaking pipe or defect. This can traditionally be conducted using an isolation device such as a squeeze-off tool where the pipe is crimped to stop flow on either or both sides of the defect. Once isolated, a tapping is made into the pipe to relieve the pressure and drain fluid prior to cutting out the defect. When the defect is repaired, the squeeze off or crimped area is released, reinstating pipe flow. However, defects typically occur around areas of pipe which were previously crimped during earlier repairs, and then require further repairs. Such repairs are typically completed with mechanical steel clamp systems and consequently suffer from the aforementioned limitations. [0009] There is therefore a need for an improved system for repairing HDPE pipes, which do not rely on traditional mechanical methods. Furthermore, such an improved system for repairing HDPE pipes should enable repair of damaged HDPE pipes across a wide range of pipe wall thicknesses, defect types and defect lengths, and which are capable of being implemented in situ with minimal pipe flow interruption.

OBJECT OF THE INVENTION

[0010] It is an object of the present invention to overcome and/or alleviate one or more of the disadvantages of the prior art or provide the consumer with a useful or commercial choice.

SUMMARY OF THE INVENTION

[0011 ] In a first aspect, although it need not be the only or the broadest aspect, the invention resides in a system for repairing a High-density Polyethylene (HDPE) pipe, the system comprising: a damaged section of the HDPE pipe; an adhesive primer applied to an outer surface of the damaged section of the HDPE pipe and substantially surrounding the damaged section of the HDPE pipe; windings of reinforcement tape wrapped around the damaged section of the HDPE pipe and covering the adhesive primer, wherein at least one winding of the reinforcement tape substantially overlaps another winding of the reinforcement tape, thereby bonding the reinforcement tape to the HDPE Pipe; at least one strapping band wrapped around the reinforcement tape; and windings of composite epoxy tape wrapped around the reinforcement tape and the at least one strapping band, wherein at least one winding of the composite epoxy tape substantially overlaps another winding of the composite epoxy tape.

[0012] Preferably, the damaged section defines a damage start point and a damage end point along a longitudinal distance of the pipe, and the adhesive primer extends longitudinally along the HDPE pipe a distance about 1.5 times the outer diameter of the pipe, both before the damage start point and after the damage end point.

[0013] Preferably, the adhesive primer is a liquid adhesion agent, or an adhesion patch which adheres to the HDPE pipe.

[0014] Preferably, the reinforcement tape or the composite epoxy tape overlaps in a spiral manner.

[0015] Preferably, the reinforcement tape interlocks with itself by overlay or by design with an interlocking shape.

[0016] Preferably, the reinforcement tape or the composite epoxy tape overlaps in a concentric manner.

[0017] Preferably, at least one winding of the reinforcement tape overlaps between 20% and 50% of another winding of the reinforcement tape.

[0018] Preferably, at least one winding of the composite epoxy tape overlaps between 20% and 50% of another winding of the composite epoxy tape.

[0019] Preferably, the reinforcement tape has a modulus of elasticity greater than that of the HDPE pipe.

[0020] Preferably, the reinforcement tape has a high temperature rating greater than that of the damaged HDPE pipe.

[0021 ] Preferably, a plurality of strapping bands are positioned equidistant from each other along the pipe.

[0022] Preferably, the composite epoxy tape comprises fiberglass.

[0023] Preferably, the at least one strapping band includes a tensioning device. [0024] Preferably, the tensioning device comprises a clamp and mechanical torsion device.

[0025] Preferably, the tensioning device comprises a ratchet type mechanical device.

[0026] Preferably, the damaged section of the HDPE pipe is at a bend in the HDPE pipe.

[0027] Preferably, the damaged section of the HDPE pipe is in a coupler of the HDPE pipe.

[0028] Preferably, the reinforcement tape comprises stainless steel.

[0029] Preferably, the reinforcement tape comprises teeth to engage with the HDPE pipe.

[0030] Preferably, the reinforcement tape comprises a mechanism to lock overlapping sections of the reinforcement tape in a plane that allows the reinforcement tape to be tensioned.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031 ] To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention are described below by way of example only with reference to the accompanying drawings, in which:

[0032] FIG. 1 is a schematic diagram representing longitudinal stress and hoop stress in a HDPE pipe when under pressure.

[0033] FIG. 2 is a cross sectional diagram of a repair system implemented on the damaged HDPE pipe, according to some embodiments of the present invention.

[0034] FIG. 3 is a schematic side view of a repaired HDPE pipe, with the defect having a damage start point and a damage end point along a longitudinal distance of the pipe, according to some embodiments of the present invention. [0035] FIG. 4 is further schematic side view of the repaired HDPE pipe of FIG. 3, showing the winding of the reinforcement tape wrapped around the HDPE pipe, in a spiral manner, and covering the adhesive primer.

[0036] FIG. 5 is yet a further schematic side view of the repaired HDPE pipe of FIG. 3, depicting a strapping band wrapped around the reinforcement tape to provide additional reinforcement.

[0037] FIG. 6 is a final schematic side view of the straight section of the repaired HDPE pipe of FIG. 3, with the composite epoxy tape covering all the preceding layers of adhesive primer, reinforcement tape and strapping bands, as applied to unify the repair system.

[0038] FIG.7 is a schematic diagram illustrating a bent HDPE pipe as repaired using a pipe repair system, according to some embodiments of the present invention.

[0039] FIG.8 is a schematic diagram illustrating an example of a reinforcement tape interlocking system based on the shape of the reinforcement tape, according to some embodiments of the present invention.

[0040] FIG.9 is a schematic diagram illustrating the top view of another interlocking tape design, according to some embodiments of the present invention.

[0041 ] FIG. 10 is a schematic diagram illustrating the side view of the interlocking tape shown in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0042] The present invention relates to a system for repairing damaged HDPE pipes. Elements of the invention are illustrated in concise outline form in the drawings, showing only those specific details that are necessary to understanding the embodiments of the present invention, but so as not to clutter the disclosure with excessive detail that will be obvious to those of ordinary skill in the art in light of the present description.

[0043] In this patent specification, adjectives such as first and second, left and right, above and below, top and bottom, upper and lower, rises and falls, upward and downward, etc., are used solely to define one element or method step from another element or method step without necessarily requiring a specific relative position or sequence that is described by the adjectives. Words such as “comprises” or “includes” are not used to define an exclusive set of elements or method steps. Rather, such words merely define a minimum set of elements or method steps included in a particular embodiment of the present invention.

[0044] According to one aspect, the present invention is defined as a system for repairing a High-density Polyethylene (HDPE) pipe, the system comprising: a damaged section of the HDPE pipe; an adhesive primer applied to an outer surface of the damaged section of the HDPE pipe and substantially surrounding the damaged section of the HDPE pipe. windings of reinforcement tape wrapped around the damaged section of the HDPE pipe and covering the adhesive primer, wherein at least one winding of the reinforcement tape substantially overlaps another winding of the reinforcement tape, thereby bonding the reinforcement tape to the HDPE Pipe; at least one strapping band wrapped around the reinforcement tape to provide additional reinforcement; and windings of composite epoxy tape wrapped around the reinforcement tape and the at least one strapping band, wherein at least one winding of the composite epoxy tape substantially overlaps another winding of the composite epoxy tape.

[0045] Advantages of some embodiments of the present invention include providing a system for repairing damaged HDPE pipes which can be used regardless of pipe wall thickness, pipe diameter, length or nature of the defect to be repaired, and pressure of the medium transitioning through the damaged HDPE pipe. Furthermore, the system does not require any mechanical means such as bolting or clamping, thereby alleviating excessive compressive stress on the HDPE pipe or relaxation of mechanical parts due to temperature and pressure cycling which can lead to premature pipe failure. The system also allows for mitigating both the hoop and longitudinal stress once applied to a damaged HDPE pipe, thereby providing a means of strengthening the repaired HDPE pipe. The system can be applied to complex pipe geometries including but not limited to bends, T junction welded pipe saddles and welded jointing couplers. In addition, the systems often can be implemented in situ while the damaged pipe remains in operation, thereby limiting downtime.

[0046] Those skilled in the art will appreciate that not all the above advantages are necessarily included in all embodiments of the present invention.

[0047] FIG. 1 is a schematic diagram representing a HDPE pipe 100 with a transitioning medium applying a pressure 101 into the inner surface of the pipe 100 and a defect 102 on the pipe 100. For example, the defect 102 may have been caused by various actions, such as faulty installation or a stone indentation or pipe vibration rubbing on a rock, and may include a puncture, cracks, or a scrape/gouge along the pipe 100. For purposes of this disclosure, consider that the defect 102 is defined by a damage start point 103 and a damage end point 104 along a longitudinal distance of the pipe 100. The pressure 101 inside the pipe 100 induces two stress components on the pipe wall: a hoop stress or tangential stress 105, which is the stress around the circumference of the pipe 100 and the longitudinal stress 106 along the length of the pipe 100.

[0048] FIG. 2 is a cross sectional diagram of a repair system of the present invention as implemented on the damaged HDPE pipe 100. The HDPE pipe 100 is first coated with a layer of adhesive primer 200, followed by windings of reinforcement tape 300, at least one strapping band (not shown in FIG. 2) wrapped around the reinforcement tape to provide additional reinforcement, and windings of composite epoxy tape 400.

[0049] During implementation of the repair system, the section of the pipe 100 near the defect 102 is exposed and then adequately cleaned to remove dirt and other debris. The cleaning can also involve lightly abrading or roughening of the HDPE pipe 100 surface to increase the surface area for the adhesive primer, thereby increasing the coverage of the adhesive primer onto the HDPE pipe 100. The adhesive primer 200 is then applied around the entire circumference of the HDPE pipe 100.

[0050] A purpose of the adhesive primer 200 is to enable the subsequent bonding of the windings of reinforcement tape 300 onto the HDPE pipe 100. The adhesive primer 200 can be, for example but not limited to, a two-part acrylic adhesive, such as Scotch-Weld™ DP8010 manufactured by the 3M company, or a liquid adhesion agent, or an adhesion patch which adheres to the HDPE pipe 100.

[0051 ] The reinforcement tape 300 can be made from, for example, a material which is noncorrosive. Such examples include stainless steel tapes or carbon fibre tapes. In one embodiment, the reinforcement tape 300 is made to deform around the HDPE pipe 100 such that it becomes cohesively set in place around the damaged section of the HDPE pipe 100. In another embodiment, the reinforcement tape 300 is manufactured from a perforated material which grips to the HDPE pipe 100 to increase the pipe strength. In another embodiment, the reinforcement tape 300 has a high temperature rating and/or a modulus of elasticity greater than that of the damaged HDPE pipe 100.

[0052] FIG. 3 is a schematic side view of the repaired HDPE pipe 100, with the defect 102 having a damage start point 103 and a damage end point 104 along a longitudinal distance of the pipe 100. The reinforcement tape 300 is wrapped in a spiral manner above the adhesive primer 200. Alternatively, the reinforcement tape 300 can be wrapped in a concentric manner. To ensure the maximum efficiency of the repair system, the reinforcement tape 300 extends longitudinally along the HDPE pipe 100 a distance a nominal 1 .5 times the outer diameter of the HDPE pipe 100, both before the damage start point 103 and after the damage end point 104 of the defect. Also, the adhesive primer 200 extends longitudinally along the HDPE pipe 100 substantially beyond the reinforcement tape 300. This ensures that the entire wrapping of reinforcement tape 300 sits on the adhesive primer 200, enabling effective bonding with the HDPE pipe 100. [0053] FIG. 4 is further schematic side view of the repaired HDPE pipe 100, showing the winding of the reinforcement tape 300 wrapped around the HDPE pipe 100, in a spiral manner, and covering the adhesive primer 200. Windings of the reinforcement tape 300 overlap about 20% of other windings of the reinforcement tape 300, thereby providing additional strength to alleviate longitudinal stress. As will be understood by those skilled in the art, the winding overlap can be further increased, for example to a 50% overlap, to compensate for higher pipe pressures. Alternatively, the reinforcement tape 300 can be wrapped in a concentric manner (not shown in FIG. 3). According to some embodiments, the winding overlap will be generally between 20% and 50%.

[0054] FIG. 5 is yet a further schematic side view of the repaired HDPE pipe 100, depicting a strapping band 500 wrapped around the reinforcement tape 300 to provide additional reinforcement. As shown in FIG. 5, a plurality of strapping bands 500 are positioned equidistant from each other along the HDPE pipe 100. In another embodiment, the strapping bands 500 are installed with a tensioning device over the reinforcement tape 300 at calculated points to bind the reinforcement tape 300 to the HDPE pipe 100. The strapping bands can be made, for example, of stainless steel, polymers or composites, or various other noncorrosive materials with sufficient mechanical strength.

[0055] FIG. 6 is a schematic side view of a straight section of repaired HDPE pipe 100, with the composite epoxy tape 400 covering all the preceding layers of adhesive primer 200, reinforcement tape 300 and strapping bands 500, as applied to unify the repair system. The windings of the composite epoxy tape 400 are wrapped in a spiral manner, and overlap about 20% of another winding of the tape 400, thereby providing additional strength to alleviate longitudinal stress. Similar to the windings of the reinforcement tape 300, the winding overlap of the composite epoxy tape 400 can be further increased, for example to a 50% overlap, to compensate for higher pipe pressures. According to some embodiments, the winding overlap will be generally between 20% and 50%. Alternatively, the composite epoxy tape 400 can be wrapped in a concentric manner (not shown in FIG. 3). The composite epoxy tape 400 can comprise, for example, fiberglass, thermoplastic or a resin based tape. [0056] Significantly, embodiments of the present invention are not limited to repairing straight sections of HDEP pipe and can be applied to more complex pipe geometries. For example, FIG.7 shows a bent HDPE pipe as repaired using a pipe repair system of the present invention. In other embodiments, for example, a system for repairing a damaged HDEP pipe according to the present invention can be applied to a coupler of an HDPE pipe.

[0057] FIG. 8 shows a reinforcement tape 805 with a hexagonal interlocking pattern, wrapped around the repaired HDPE pipe 100. The hexagonal reinforcement tape 805 can be applied circumferentially or longitudinally to the repaired HDPE pipe 100 and provide lateral or longitudinal reinforcement without requiring overlap of the tape windings. In other embodiments, the interlocking pattern may be of a different shape, such as another polygonal shape, and may have teeth (not shown) that substantially penetrate the surface of the repaired HDPE pipe 100. A penetration depth from the surface should be preferably less than 10% of the repaired HDPE pipe wall thickness.

[0058] FIG. 9 shows the front view of another example of interlocking reinforcing tape 900. The interlocking reinforcing tape 900 has a longitudinal ridge 905 and teeth 910. In one embodiment, the interlocking reinforcing tape 900 is a steel band, but alternatively could comprise another metal or a composite construction. The teeth 910 may be indentations or perforations in the tape. Furthermore, the teeth 910 substantially penetrate the repaired HDPE pipe, preferably by less than 10% of the repaired HDPE pipe wall thickness.

[0059] FIG. 10 shows a side view of the interlocking reinforcing tape 900, where a longitudinal groove 1005 is positioned opposite to the longitudinal ridge 905, on the other side of the interlocking reinforcing tape 900. This arrangement allows for two consecutive windings of the interlocking reinforcing tape 900 to be fastened to each other when the longitudinal ridge 905 embeds in the longitudinal groove 1005. Those skilled in the art will appreciate that different positioning of the longitudinal ridge 905 and the longitudinal groove 1005 in alternative embodiments, such as having the longitudinal ridge 905 on the right side of the teeth 910 and the longitudinal grove 1005 on the left side of the teeth 910, or vice versa, will allow for winding and fastening the interlocking reinforcing tape 900 around the repaired HDPE pipe 100 in a spiral manner without necessitating cutting the interlocking reinforcing tape 900.

[0060] Both the longitudinal groove 905 and the teeth 910 enable locking the tape 900 to an adjacent interlocking reinforcing tape 900 winding and onto the repaired HDPE pipe. Such an embodiment provides a system that can be robustly tensioned for full lateral and longitudinal reinforcement of the repaired HDPE pipe. In a further embodiment, the interlocking reinforcing tape 900 slides on the tape on the overlapping section during application and tensioning, whereas in the non-overlapping section the teeth 910 will grip and pull into the surface of the pipe 100.

[0061 ] Those skilled in the art will appreciate that the present invention can be implemented on various types of pipe repairs, as some acrylic adhesives used as the adhesive primer may also bond metals, ceramics, wood and various plastics.

[0062] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. Numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. Accordingly, this patent specification is intended to embrace all alternatives, modifications and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.