Patent Application
20170113426
Field of the Invention
This invention relates to a system and method for repairing leaks in in-service utility pipelines including natural gas pipelines. More specifically this invention relates to a mold that is positioned in proximity to a leak in a pipeline and injected with an adhesive to seal the leak.
Discussion of Related Art
Mechanical couplings and fittings, e.g., tees, valves, elbows, etc. are used widely throughout the natural gas industry in association with steel, cast iron, and plastic pipelines. Mechanical couplings and fittings generally all share a similar design in that rubber seals are compressed around pipes to be plumbed to create a seal. One disadvantage of this design is the lack of substantial axial (pullout) restraint for many of the coupling and fitting designs (types). After years of service, these couplings or fittings may develop a leak due to thermal expansion contraction of the pipeline, relaxation of the rubber seals, corrosion, or even gas composition changes. Indeed, recent failures of mechanical couplings have heightened concerns about their continued safety in natural gas distribution systems. Thus, it is desirable to have a means for remediating leaking mechanical couplings and fittings without having to remove the coupling or shut down the pipeline. It is also highly desirable to have the option of adding axial restraint at the same time. It will be appreciated that the ability to perform a repair without removing the coupling or fitting, without shutting down the pipeline, and without using bypass or cut-out methods for maintaining fluid flow would both save time and reduce costs associated with shutting down the pipeline.
Numerous methods for sealing connecting pipe sections and leaks are taught in the prior art. See U.S. Pat. No. 6,276,726 which teaches a pipe clamp closing over a leak; U.S. Pat. No. 5,372,391 which teaches an internal pipe attachment mechanism which employs a sealing assembly that is set by crushing the sealing assembly through setting of the mechanical connection between pipe sections; U.S. Pat. No. 4,713,870 which teaches insertion of an expandable sleeve into a pipe and expanding the sleeve against the pipe wall containing the leak to cover and, thus, seal the leak; and U.S. Pat. No. 4,652,023 which teaches a repair coupling employing a sealing liner having circumferential ribs which seal against the pipe wall on both sides of the leak to effectively isolate the leak. While all of these sealing methods address the problem of repairing a leak in a pipe, none of the methods results in a permanent plugging of the leak.
U.S. Pat. No. 8,296,915 teaches another method for repairing an in-service fluid conduit. The method of this patent uses a flexible fluid venting device that is attached to the pipe around the pipe leak. A composite repair material is applied to the fluid venting device and allowed to cure. However, this method does not repair all types of leaks, does not teach a rigid mold and does not disclose a step of pressurizing the composite repair material at the repair site.
The invention is directed to a system and method for repairing utility pipelines while the pipeline remains in service, for example natural gas pipelines and other similar pipelines. Alternatively, the system and method of this invention may be used to repair other types of fluid containment vessels.
The system of this invention includes a mold to encapsulate a leak in the pipeline and an injected adhesive. The mold preferably includes an injection port for injecting the adhesive and a venting port to allow for the release of leaking fluids and/or gases. The mold is preferably manufactured of metal or other rigid and durable materials which are able to withstand pressure of the injected adhesive. In a preferred embodiment, the mold is sized and shaped to accommodate a specific pipe and/or pipe component shape, for example sized to fit around a specific pipe diameter of a straight section of pipe. The mold may also be designed to accommodate specific issues related to a specific type of leak, such as leaks around threaded fittings, leaks with surface corrosion around the leak, and/or a leak near a coupling. The molds preferably further include an o-ring or another type of gasket for forming a tight seal between the mold and the pipe and/or mold halves. After the adhesive cures to from a cast sealing the leak, the molds may be removed or remain attached to the pipe.
The method of this invention preferably includes a step of attaching the mold to the pipe to create a mold cavity defined by an interior surface of the mold and an outer surface of the pipe. The mold should at least partially surround a leak to be repaired, with at least the venting port providing a release for gas or fluid, for example natural gas, to escape the mold and the pipe. With the mold attached to the pipe and surrounding the leak, the method of this invention further includes injecting an adhesive into the injection port into the mold cavity. In an alternative embodiment, the adhesive may be replaced with or combined with another sealant such as, but not limited to, polyurethane, polyureas, polyester resins, vinyl ester resins, epoxy resins, butyl rubber, latex, silicone, and combinations thereof. The injected adhesive is preferably pushed into the mold cavity with a gas propellant, such as air or nitrogen. Once the mold cavity is filled with adhesive, the venting port is closed and the injected adhesive is pressurized to a pressure greater than an internal pressure of the pipe. Thereafter, the adhesive is allowed to cure sealing the leak in the pipe. After curing, the injection port and the venting port are preferably removed. If the mold is re-useable, the mold may also be removed. Alternatively, the mold may remain attached to the pipe to provide additional support to the repaired pipe. In an embodiment of this invention, the repaired pipe may also be wrapped with a commercially available pipe wrap material for added support and protection.
The system of this invention may further include a sleeve positioned on the leak prior to the attachment of the mold and adhesive. The sleeve providing additional strength and support to the repaired pipe. The sleeve may comprise fiber glass, carbon fiber, polymer fiber and other types of compression wraps.
These and other objects and features of this invention will be better understood from the following detailed description taken in conjunction with the drawings, wherein:
This invention is directed to a system and method for repairing leaks in in-service utility pipelines, for example natural gas pipelines, or other fluid containment vessels, without having to interrupt or shutdown the pipeline. In addition, the method of this invention enables the repair of a leak in a natural gas pipeline without having to install some form of bypass means to divert the natural gas around the leaking section of the pipeline to maintain the flow of natural gas in order to repair the leak. In addition to “in-service” fluid containment vessels, the method of this invention may also be applied to a pressurized fluid container having a leak through which the fluid within the container exits the container. Finally, the method of this invention may even be applied to a fluid containment vessel having an opening through which a fluid could leak but does not actually leak, such as where the internal fluid containment vessel pressure and the external fluid containment vessel pressure are in equilibrium.
As shown in the embodiment of
c show another embodiment of the mold 10 of this invention. In this embodiment, the mold 10 is designed for repairing a leak between a pipe 100 and a coupling 200. As best shown in
In a preferred embodiment of this invention, as shown in
As shown in
The invention illustratively disclosed herein suitably may be practiced in the absence of any element, part, step, component, or ingredient which is not specifically disclosed herein.
While in the foregoing detailed description this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.
