Cutting by use of rotating axially moving tool – Means to drive tool – Including means to move tool along tool-axis
Reexamination Certificate
2000-09-21
2003-04-22
Bishop, Steven C. (Department: 3722)
Cutting by use of rotating axially moving tool
Means to drive tool
Including means to move tool along tool-axis
C408S138000, C137S318000
Reexamination Certificate
active
06551034
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a drilling apparatus for tapping into a fluid containing vessel. The present invention further preferably relates to the drilling apparatus tapping into the vessel from a valve device connected with the vessel.
BACKGROUND OF INVENTION
Following the placement of a vessel, such as a pipe, on or beneath the ground surface, it may be necessary or desirable to make a connection with the vessel or to enter the vessel at a location where a hole or opening does not pre-exist. The operation of drilling or cutting a hole or opening in the vessel to facilitate the desired connection is often complicated by the presence of various fluids within the vessel, which fluids are typically under pressure and may be volatile or environmentally hazardous. Thus, in these circumstances, it is preferable to be able to make the desired connection without the necessity of interrupting the operation of the vessel and preferably in a manner inhibiting the leakage of any fluids from the vessel.
The cutting or drilling of an opening or hole into a vessel containing fluid, typically under pressure, is referred to as “hot tapping.” Hot tapping permits the desired connection to be made without significantly interfering with the use or operation of the vessel. Thus, hot tapping is particularly applicable to industries such as the petroleum industry where a connection may be required or desired to be made to a pipeline, while minimizing any interference with the flow of fluid through the pipeline or disruption in service, as well as inhibiting the leakage of any fluids from the pipeline.
Various tapping machines and apparatuses have been developed for drilling or cutting a hole or opening into a fluid containing vessel. Typically, the hot tapping operation is accomplished by tapping into the vessel from a valve device connected with the vessel. More particularly, the valve device may be directly mounted or attached with the outer wall of the vessel or may be mounted or attached with a standpipe or branch pipe or connection extending from the outer vessel wall to the ground surface. In either case, the valve device in place is typically not in fluid connection with the vessel, in that an opening or hole does not pre-exist. The hot tapping operation establishes the desired fluid communication with the vessel by cutting or drilling the hole or opening in the outer vessel wall.
Where no valve device pre-exists, a valve device is typically welded, clamped or otherwise mounted or attached to the outer wall of the vessel prior to proceeding with the hot tapping operation. However, in these cases where the vessel is located underground, a considerable amount of time and expense may be incurred to access or excavate the vessel to place the valve device, subsequently perform the tapping operation and then backfill the excavation.
As a result, often times, in anticipation of the potential future need to establish a further connection with the vessel, the vessel is initially placed with a pre-existing valve device to permit easier access at a later date. Where the vessel is located underground, as discussed above, in anticipation of the need for a potential future connection, the vessel may include a standpipe or branch pipe or connection extending from the outer vessel wall to the ground surface. The valve device is then connected with the standpipe at or near the ground surface for relatively easy access without the need to excavate the site.
The hot tapping operation is simply performed by mounting the hot tapping apparatus to the valve device and running the drilling or cutting tool of the tapping apparatus through the open valve device and the standpipe or branch pipe to contact the vessel and cut or drill through the vessel wall. However, where the vessel is underground, the tapping apparatus must have sufficient dimensions to permit the drilling or cutting tool to extend through the length of the standpipe to the vessel wall beneath the surface. After the opening has been cut, the drilling or cutting tool is withdrawn and the valve device is closed to prevent the leakage of any fluids from the vessel. Any pressure within the tapping apparatus may then be bled off and the tapping apparatus may be removed from the valve device.
Thus, the tapping apparatus preferably performs two primary functions. First, the apparatus supports the drilling or cutting tool such that it may drill or cut the hole or opening in the vessel wall. Second, the apparatus preferably provides a feed mechanism for advancing or retracting the drilling or cutting tool towards or away from the vessel wall. In addition, the feed mechanism is preferably relatively easy to access and operate and the overall apparatus is of a relatively strong or sturdy construction.
Various devices or apparatuses have been developed for hot tapping fluid containing vessels. However, none of these devices have been found to be completely satisfactory.
For instance, Canadian Patent No. 426,813 issued Apr. 17, 1945 to Mercier, U.S. Pat. No. 4,331,170 issued May 25, 1982 to Wendell, U.S. Pat. No. 4,332,272 issued Jun. 1, 1982 to Wendell and U.S. Pat. No. 4,680,848 issued Jun. 21, 1987 to Goldner describe a tapping apparatus in which a drill bit is rotated through a drill stem, rod or shaft having a lower end attached with the drill bit. However, the drill bit is advanced towards the vessel wall by simply applying a direct longitudinal or axial force, typically manually, at an upper end of the drill stem, rod or shaft to move the drill bit relative to the vessel wall. In other words, no particular feed mechanism is provided for advancing or retracting the drill bit.
Other forms of tapping apparatus provide for a particular feed mechanism. However, the specific construction or configuration of the feed mechanism may result in a relatively unsturdy or weakened apparatus structure. Further, the specific construction or configuration often requires the operation of the feed mechanism from a location adjacent the upper end of the apparatus, which may be difficult to access depending upon the overall length or height of the tapping apparatus.
For instance, Canadian Patent No. 531,194 issued Oct. 2, 1956 to Mueller, Canadian Patent No. 645,089 issued Jul. 17, 1962 to Milanovits et. al., and U.S. Pat. No. 2,972,915 issued Feb. 28, 1961 to Milanovits et. al., Canadian Patent No. 675,771 issued Dec. 10, 1963 to Vemoov, Canadian Patent No. 675,890 issued Dec. 10, 1963 to Vernooy, U.S. Pat. No. 3,068,726 issued Dec. 18, 1962 to Vernoov and Canadian Patent No. 1,178,830 issued Dec. 4, 1984 to Yarnell provide for an inner drilling rod, referred to as a drill stem, drill rod or boring bar, attached with the drill bit, which is contained within an outer feed mechanism in a manner such that the inner drilling rod is coaxial with the outer feed mechanism. In other words, the longitudinal axis of the inner drilling rod coincides with the longitudinal axis of the outer feed mechanism. The outer feed mechanism is variously described as an outer feed sleeve, feed tube or feed or holder nut and is configured to permit the passage of the inner drilling rod therethrough. More particularly, rotation of the outer feed mechanism produces axial movement of the inner drilling rod in order to advance or retract the drill bit relative to the outer vessel wall.
The coaxial nature of the apparatus and the need to contain the inner drilling rod within the outer feed mechanism tends to result in a relatively complex structural arrangement of the apparatus and a relatively weakened structure of the apparatus overall. Further, as in Meuller, the Milanovits et. al. references and the Vernooy references, the complexity and weakening of the structure of the apparatus may be exacerbated by further containing both the drilling rod and the feed mechanism within a single housing or chamber, which is also coaxial with the drilling rod and the feed mechanism. Typically, the feed mechanism is threadably engaged with an inner surface of the housing such that rotation of
Nyhuis Albert Hendrix
Nyhuis David Albert
Bishop Steven C.
Kuharchuk Terrence N.
Rodman & Rodman
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