Fluid handling – Processes – Cleaning – repairing – or assembling
Reexamination Certificate
2000-03-21
2001-07-10
Walton, George L. (Department: 3753)
Fluid handling
Processes
Cleaning, repairing, or assembling
C137S015090, C137S015150, C137S315010, C137S318000, C138S089000, C138S097000
Reexamination Certificate
active
06257266
ABSTRACT:
BACKGROUND AND FIELD OF INVENTION
This invention relates to a method and apparatus for the in-line repair or replacement of pipelines, and more particularly to a novel and improved method and apparatus for the in situ repair or replacement of natural gas pipelines.
Numerous methods have been devised for the repair or replacement of gas pipelines. One method requires a trench to be excavated from a stop valve located upstream from the section of pipeline to be replaced. Manipulating the valve then stops the gas flow and the pipeline section is replaced. This method was improved by the development of devices that temporarily block the flow of gas in a pipeline. This method did not require the excavation of a stop valve but functioned by inserting into the pipeline a device that could be expanded and thereby block the flow of gas in a pipeline. Both of these methods were very time-consuming and labor-intensive. Another method allows the gas to escape to the atmosphere while the pipeline is replaced. However because of the long term and continuous exposure to gas, this method required the use of special equipment such as fire resistant clothing and respirators for the workers. Additionally, the released gas constitutes a safety hazard.
Devices for temporarily stopping the flow of gas in a pipeline are shown in U.S. Pat. Nos. 5,590,676 and 4,127,141. The '676 patent discloses a stopper for an opening in a gas pipeline side wall having an expansion plug that can be axially compressed, thereby expanding the plug to fill and seal the pipe. The '141 patent teaches a method and apparatus for sealing an opening in the side wall of a pipeline that includes a plug wrench having an elongated stem and a stopper rod that can be moved relative to a threaded jack member to cause a resilient plug to radially expand.
Tools for temporarily stopping the flow of gas in a pipeline are shown in U.S. Pat. Nos. 5,592,965; 4,597,147 and 5,819,804. The '965 patent discloses a valve stop changer including a tool having a tubular expandable plug member which is compressed and expanded by rotating a handle to move into sealed engagement with a pipe. The '147 patent discloses a changer tool for use in removing a valve under pressure. The tool is a shaft supporting a compressible rubber plug that is inserted through the valve into the upstream pipe. The plug is then compressed into sealed engagement with the inner wall of the pipe. The '804 patent is directed to a specific improvement in an expansion tool for a pipeline.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a novel method and apparatus for repairing or replacing a pipeline that doesn't require sidewall insertion seal off devices. Another object of the present invention is to provide a novel method and apparatus to seal off the pipeline using an axially insertable device in a rapid, efficient manner. It is a still further object of the present invention to provide a novel method and apparatus for quickly and efficiently repairing the old pipeline and at the same time replace the old pipeline with a new pipeline and facilitates replacement of metal pipeline sections with new plastic lines in a minimum number of steps.
The present invention is directed to a method and apparatus to temporarily seal off a pipeline thorough the combined use of a transition fitting and an axially insertable expandable tool. The transitional fitting can be any tubular device with some means to temporarily seal the pipeline off after completing the first step of joining the transition fitting to the upstream line, following which the other end of the transition fitting can be joined to a new or replacement pipeline. The transition fitting can be one continuous metal pipe if it is to be joined to an existing metal downstream pipeline or can be a combination metal and plastic tubular section if it is to join a metal pipeline and plastic pipeline.
In the preferred form, the transition fitting has a tubular metal and plastic portion. The plastic portion is resilient so that it can be compressed for temporarily sealing off the transition fitting. An expansion tool, having an elongated handle control and an expandable portion is then inserted through the transition fitting and into the upstream pipeline. The expandable portion is expanded by the handle control to form a seal with the inner surface of the upstream pipeline to prevent the escape of gas from the pipeline while the metal end of the transition fitting is being joined to the metal pipeline. The expandable portion is then contracted thereby breaking the seal with the pipeline and is removed from the pipeline and the transition fitting. The plastic portion of the transition fitting is then compressed to prevent the escape of gas into the atmosphere as the plastic end of the transition fitting is being joined to the downstream plastic pipeline. Once joined, the compression is removed to permit the plastic pipe portion to return to its original shape and the gas in the pipeline is free to flow through the new replacement pipeline.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description that follows may be better understood. There are additional features of the invention that will be described which will form the subject matter of the claims appended. It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed are for the purpose of description and should not be regarded as limiting. As such those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the present invention. It is important therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
The above and other objects, advantages and features of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of preferred and modified forms of the present invention when taken together with the accompanying drawings in which:
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Reilly John E.
Walton George L.
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