Patent Application
20100236639
The present invention relates to a system and method for accessing a pressurized gas pipeline.
There are currently a number of systems available and in use for drilling and tapping a pressurized gas pipeline. One such system is known as the “ALH system-one”, and another is known as the “Mueller B-101”. The drilling and the tapping of the access hole into the gas pipeline is often just the first step in what is usually a much more involved maintenance procedure. For example, it may be desirable to install a service tee into the pipeline for later access by a service technician. In other situations, it may be necessary to insert and deploy a balloon stopper into the pipeline to completely cutoff the flow of gas downstream from the stopper. In an even more complicated maintenance procedure, it may be necessary to install a bypass pipe around a portion of the pipeline that requires maintenance, and then install two balloon stoppers just inside the bypass pipe so that the flow of gas can continue both upstream and downstream from where the stoppers are deployed and the maintenance is being performed. In such a case, it may be necessary to drill and tap four separate holes in the pipeline—two holes to accommodate the bypass line, and two holes to accommodate the two balloon stoppers. Maintenance is then performed between the two balloon stoppers, where the flow of gas is completely shutoff.
It is common practice in the utility industry to allow gas to escape from the pipeline into the atmosphere when installing a bypass line or balloon stoppers as described above. This procedure can result in a loss of downstream pressure, to the point where pilot lights in appliances go out, and have to be relit after the flow of gas returns to a normal pressure. This can be a particular problem in the north during the winter months, when furnaces and hot water heaters are running almost constantly.
In addition to the disruption and service to customers, the release of gas from the pipeline into the atmosphere is an unwanted source of additional green house gases which can have a detrimental effect on the environment. Moreover, the release of gas from the pipeline while the service technicians are performing maintenance can pose safety concerns related to inhalation and potential explosion of the released gas. Therefore, a need exists for a system and method for inhibiting the release of gas from a pressurized gas pipeline while accessing the pipeline.
Embodiments of the present invention provide a method for inhibiting gas release while accessing a pressurized gas pipeline. In one embodiment, the pipeline has a threaded hole through the wall of the pipeline that provides access from an ambient environment outside the pipeline into the interior of the pipeline. A valve covers the threaded hole, and is attached on an outside of a pipeline. The valve has an open position for facilitating access to the threaded hole from outside the pipeline, and a closed position for sealingly covering the threaded hole to inhibit gas transfer from inside the pipeline to an ambient environment outside the pipeline. As used herein, the term “inhibiting” means that the transfer of gas is generally prohibited; however, it is understood that even under tightly controlled conditions, some minute quantities of gas may still escape, and as such gas escape is not completely prohibited. It is worth noting, however, that the quantity of gas entering the atmosphere can be reduced by orders of magnitude through proper implementation of embodiments of the present invention.
The method described above includes the step of magnetically engaging a magnetic pipe plug holder and a threaded pipe plug, which is sized to be threaded into the threaded hole in the pipeline. A sealing member, or housing, is provided for the pipe plug and pipe plug holder, and it is configured in such a way as to allow sealed movement of the pipe plug holder, and therefore the magnetically engaged pipe plug, in both a linear and rotational fashion. One way in which the pipe plug holder can be linearly or rotationally moved relative to the housing while still maintaining a gas seal, is to provide a rod that extends through another sealing member, or sealed bushing, in the housing. The end of the rod may have a female portion adapted to receive a shank of the magnetic plug holder.
The method described above may also include the step of sealingly engaging the housing to a portion of the valve that is positioned on the pipeline. The valve is then opened, and the magnetically engaged pipe plug is disposed through the open valve and into the threaded hole. Rotating the rod from outside of the housing causes the pipe plug holder, and hence the magnetically engaged pipe plug, to be rotated and threaded into the hole in the pipeline. The pipe plug holder can then be extracted from the pipe plug by linearly moving the rod away from the pipe plug such that the magnet disengages. The housing can then be removed from the valve, and the gas pipeline has been plugged while gas escape into the atmosphere has been inhibited.
Embodiments of the invention may include an access port in the housing having a vent valve disposed therein, where the vent valve can be opened and closed as desired. The access port may have a very small diameter such that if gas were to escape from the pipeline through the housing and out of the vent valve, it would be a very slow process that could be quickly stopped before any undesirable quantity of gas escaped. After the pipe plug is threaded into the hole in the gas pipeline, the vent valve can be opened prior to removing the housing from the pipeline. In this way, it can be determined whether the insertion of the pipe plug, which is not visible to the pipeline technician, was inserted correctly and has provided a seal to keep gas from escaping from the pipeline. A small quantity of gas may be in an interior portion of the housing, even if the pipe plug has been inserted correctly. Therefore, once the access port is opened, a technician can determine whether a certain amount of gas is exiting through the port, which would indicate a poor seal between the pipe plug and the pipeline. If this occurs, the access port can be closed, and the pipe plug rethreaded into the pipeline.
As noted above, installing a threaded plug into a pipeline is often the first step of a much larger maintenance procedure, which may include installing a bypass line, a service tee, or one or more balloon stoppers into the pipeline. To address this situation, embodiments of the present invention include installing a strap saddle on an outside of the pipeline such that an opening in the saddle is generally aligned with the pipe plug. Strap saddles of this type will provide a seal against an outside surface of the pipeline generally around the installed pipe plug. A valve is then attached to the saddle, although it may require one or more threaded adapters, nipples, reducers, etc. to effect this attachment. Any number of different types of valves can be used in a method such as this, including pancake valves, globe valves, or any other valve that will allow access to the threaded plug and will sealingly engage the strap saddle such that closing the valve when the pipe plug is removed will effectively stop gas from leaking from the pipeline.
Embodiments of the present invention include the reversal of some of the steps used to insert the pipe plug into the pipeline. For example, after the strap saddle and valve are attached to the pipeline, a magnetic plug holder can be disposed inside a housing, which is then sealingly attached to a portion of the valve. The valve can then be opened and the magnetic plug holder lowered through the valve and onto the pipe plug that is threaded into the gas pipeline. Rotating a shaft that extends through the housing will rotate the threaded plug until it can be removed from the pipeline. The magnetic plug holder magnetically engages the plug, and as the shaft is lifted, the plug holder and plug exit the valve, which is then closed to form a seal to the outside atmosphere. The housing can then be removed from the valve.
At this point, it may be desirable to install a balloon stopper into the pipeline to stop the flow of gas downstream from the stopper. Embodiments of the present invention include a sealing member, or sealing adapter, that is configured to sealingly engage a launch tube that is part of a balloon stopper system. The sealing adapter can be sealingly engaged with the launch tube, and then sealingly attached to a portion of the valve. For example, one such sealing adapter can be a threaded bushing specifically configured with an interior seal or seals that are sized to allow the launch tube to slide through the bushing, while sealing to an interior seal or seals within the bushing. The bushing can then be threaded into a female threaded portion of the valve, the valve can be opened, and the launch tube inserted through the valve and threaded into the threaded hole in the pipeline, all while escape of gas from the interior of the pipeline is inhibited. The balloon stopper can then be deployed in the pipeline to stop the flow of gas through the pipeline.
The sealing adapter can be part of a system of the present invention which can include one or more apparatuses specifically configured to provide for accessing and installing devices into a pressurized gas pipeline while inhibiting the escape of gas from the pipeline into the atmosphere. Embodiments of a system of the present invention can include a magnetic plug holder that has a receiving portion configured to mate with a portion of a pipe plug such that rotation of the plug holder rotates the pipe plug. The magnetic plug holder can also include an attachment portion for attaching the plug holder to a shaft such that rotation of the shaft rotates the attachment portion and the receiving portion. In some cases, a pipe plug may have a projecting head that can be square, hexagonal, or some other geometric shape. In such cases, the receiving portion of the magnetic plug holder can be configured with a recess that is sized and shaped to receive the projecting head of the pipe plug. In other situations, the pipe plug itself may have a recess, in which case, the receiving portion of the plug holder may include a projection configured to fit inside of the recess in the pipe plug.
Embodiments of the present invention can also include a hand cylinder that has a number of elements, such as a first elongate member, which can be, for example, a holder rod. This rod can be configured to be inserted into a housing in a sealing fashion such that the rod can be moved linearly and rotationally inside the housing, while maintaining a seal that would inhibit the escape of gas from inside the housing to outside the housing. The system can also include an adapter configured for attachment to one end of the holder rod and further configured to engage the magnetic plug holder. The adapter is sized to be moveable through an interior of the housing, such that when the housing is sealingly engaged with the valve and the plug holder is attached to the adapter and magnetically engaged with the pipe plug, the pipe plug can be linearly disposed through the valve by linear movement of the holder rod, while escape of gas from the pipeline is inhibited.
The hand cylinder 16 also includes a housing 22, which in one embodiment may be generally configured as a right circular cylinder as shown in detail in
One of the advantages of the system 10 is that it allows a device such as a pipe plug 26 to be inserted into and removed from a threaded hole 28 that is disposed in the pipeline 12, while inhibiting the release of gas from the pressurized pipeline 12 to an ambient environment 29 outside the pipeline 12. In some applications, a gas pipeline, such as the pipeline 12, may provide gas to many customers, even though it operates at a relatively low pressure, such as one pound per square inch (psi) or less. Although it works very well for such applications, the system 10 can also work in applications where the gas is much more highly pressurized, for example, at or near 60 psi. In order to inhibit the release of gas while the plug 26 is being inserted or extracted, the system 10 includes a number of features. For example, one end 30 of the housing 22 includes tapered pipe threads 32 that provide a sealing engagement with a slide valve 34 that is attached to a strap saddle 36 by a nipple 38.
The strap saddle 36 is attached to an outside 39 of the pipeline 12 such that an opening 41 in the saddle 36 is generally aligned with the pipe plug 26 in the pipeline 12. A portion 45 of the saddle 36 sealingly engages the outside 39 of the pipeline 12. In order to keep gas from escaping from the other end 40 of the housing 22, a bushing 42 is provided between the housing 22 and the rod 18. The bushing 42 is shown in more detail in
Referring to
The recess 52 may be approximately 0.83 inches square to accommodate a standard 1 inch pipe plug. Similarly, it can be made larger such as 0.96 inches for a 1¼ inch plug, or 1.15 inches for a 1½ inch plug. Of course, different sizes and configurations of a recess, such as the recess 52, are contemplated in order to accommodate different types of pipe plugs. In addition, although the receiving portion 52 is illustrated as a recess, it could be, for example, a projection, to accommodate a pipe plug having a recess, instead of a projecting head.
The plug holder 14 also includes a magnet 54, which may be, for example, a 6 pound magnet, which is strong enough to lift standard sized pipe plugs, while still making it relatively easy to disengage the plug holder 14 from the pipe plug. The plug holder 14 also includes an aperture 56 transversely disposed through an attachment portion, which in the embodiment shown in
Returning to
The method discussed above describes the steps of using the system 10 to remove a pipe plug from a pipeline, such as the pipeline 12. The system 10 can also be used to insert a pipe plug, by reversing the steps described above. In addition, the system 10 can also be used to insert a pipe plug immediately after a threaded hole has been drilled and tapped into a pipeline, such as the pipeline 12. For example, both the ALH system-one and the Mueller B-101 have a valve that can be opened and closed to drill and tap a pipeline without releasing gas into the atmosphere. The magnetic plug holder 14 of the present invention is configured for attachment to a portion of the Mueller B-101 system after the drill and tap head is removed. In this way, a pipe plug, such as the plug 26 shown in
Similarly, the system 10 can also be used with the ALH system-one by sealingly connecting the housing 22 to an adapter connected to the valve already present in the ALH system-one. Insertion and extraction of a pipe plug using the present invention provides a fast and efficient mechanism for what is very often a first step in a much larger pipeline maintenance program. As described below, some maintenance procedures, such as installing a bypass line and balloon stoppers, require the drilling and tapping of many holes. Thus, the advantages of inhibiting gas release by using the system and method of the present invention can be multiplied many times for a single maintenance operation.
Looking at some of the details of the components of the system 10, the holder rod 18 shown in
As discussed above, the system 10 is configured such that the rod 18 can be move linearly and rotationally through the housing 22 while the release of gas from inside the pipeline 12 is inhibited. To help accommodate this, a bushing 42, shown in
As mentioned above, installing or removing a pipe plug is often only the first step in a larger pipeline maintenance program. For example, it may be desirable to install a balloon stopper in a gas pipeline to stop the flow of gas to a particular portion of the pipeline.
The system 10 further includes a threaded bushing 100 that is shown in detail in
Using embodiments of the present invention, the bypass 118 may be installed while release of gas from the pipeline 112 is inhibited. In particular, first and second sections, or risers 120, 122, of the bypass line 118 can be installed by a method that uses the present invention to inhibit gas release. For the riser 120, a hole 124 is drilled and tapped in the pipeline 112, for example, using a known drill and tap system. A pipe plug (not shown) can then be installed in accordance with a method of the present invention as described above. The drilling and tapping apparatus can be removed and a strap saddle 126 and valve 128 attached to the pipeline 112. The pipe plug can then be removed in accordance with a method of the present invention as described above, and the valve 128 closed. The riser 122 can be installed similarly, using a strap saddle 130 and valve 132 to cover a hole 134 in the pipeline 112. Once the risers 120, 122 are installed, a connecting section 128 can be installed. It is understood that in practice a number of different elbows, couplings, unions, or other sections of bypass pipe may be used to complete the connection.
In addition to installing the bypass 118, it is also necessary to install two separate balloon stopper systems 138, 140. Using a system and method of the present invention, such as described above, holes can be drilled and tapped for each of the balloon stopper systems 138, 140, and each of them can be inserted and their respective balloon stoppers 142, 144 deployed while at every step the release of gas from inside the pipeline 112 is inhibited. Each of the balloon stopper systems 138, 140 cooperates with a threaded bushing seal 100′, 100″ to effect a seal against a respective launch tube and inhibit gas release. Use of the system and method of the present invention provides a way to eliminate or severely reduce the escape of gas during pipeline maintenance operations, and therefore, reduce or eliminate the detrimental effects associated with the release of gas from a pipeline.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.
This application claims the benefit of U.S. provisional patent application Ser. No. 61/154,264, filed on 20 Feb. 2009, which is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61154264 | Feb 2009 | US |
