Removable oil pipeline branch plug

A pipeline plug having a seal assembly and a slip assembly coupled to the seal assembly. The slip assembly moves from a retracted position to an expanded position when the seal assembly moves from a disengaged position to an engaged position. The slip assembly frictionally engages the internal wall of a pipe when in the expanded position. The force exerted on the pipeline plug by fluid within the pipe increases the force by which the slip assembly engages the internal wall of the pipe. The plug is removable from the pipe without damaging the plug by moving the seal assembly back to the disengaged position. A method of sealing a pipeline using the pipeline plug.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

Not applicable.

STATEMENT REGARDING JOINT RESEARCH AGREEMENT

The invention claimed herein was made by, or on behalf of, the parties to, and as a result of activities undertaken within the scope of, a “joint research agreement,” as defined in 35 U.S.C. § 100, by and between Tallgrass Pony Express Pipeline, LLC and Southwest Research Institute that was in effect on or before the effective filing date of the claimed invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to systems and methods for temporarily blocking the flow of gas or fluid within a pipe, and in particular, to a removable pipeline plug and method for using the same.

2. Description of Related Art

Pipelines are conventionally used to transmit gas or fluid. At times, it is desirable to temporarily block the flow of fluid or gas within a pipeline. For instance, when a component of a pipeline, such as a valve, needs to be repaired or replaced, the flow of gas or fluid within the valve must be stopped prior to removal of the valve for repair or replacement.

A variety of different plugs are known for stopping flow through a pipeline. One type of plug includes an inflatable bag that is inserted into the pipeline in a deflated state and is then inflated to sealingly engage the internal walls of the pipe. While inflatable plugs are often effective for low pressure gas pipeline applications, they are generally not effective for higher pressure applications, which may cause the plug to be pushed through the pipe. Further, they are prone to ripping or tearing, and thus generally cannot be relied upon for a wide range of applications.

Another known method for plugging a pipe involves inserting a cylindrical plug through an access hole that is drilled through the side of the pipe. A fitting may be welded or attached to the outside of the pipe to position and retain the plug. While these types of plugs are generally suitable for their intended purpose, they require drilling a hole in the side of the pipe, which must be sealed with a fitting when the plug is removed. They are not suitable for axial insertion through a hole in the end of the pipe.

There are also a variety of packer tools that include seals to isolate zones of an oil or gas well. The packer tools are inserted axially through the pipe, but are typically relatively complex and are set in place by applying downward force on one portion of the packer tool, while the another portion of the tool is pulled upward. Many packer tools are also not removable from the wellbore without permanently damaging the tool by, for example, drilling through it.

BRIEF SUMMARY OF THE INVENTION

A pipeline plug in accordance with one embodiment of the invention described herein includes a seal assembly and a slip assembly coupled to the seal assembly. The seal assembly has a pressure engaging surface and a slip engaging surface. The seal assembly is movable with respect to the slip assembly between an engaged position and a disengaged position. The slip assembly has an outer surface that is movable from a retracted position to an expanded position. The outer surface is in the retracted position when the seal assembly is in the disengaged position. The slip engaging surface moves the outer surface to the expanded position when the seal assembly moves from the disengaged position to the engaged position. A force exerted on the pressure engaging surface causes the slip engaging surface to exert a force on the slip assembly that opposes movement of the outer surface from the expanded position to the retracted position. When a force is exerted on the pressure engaging surface the seal assembly is movable from the engaged position to the disengaged position and the outer surface is movable from the expanded position to the retracted position. The pipeline plug is preferably adapted to be positioned within a pipe and sealingly engage an internal wall of the pipe to prevent fluid from flowing past the pipeline plug. When the seal assembly is in the disengaged position and the slip assembly is in the retracted position, the pipeline plug may preferably slide into a pipe through an opening in the end of the pipe. When the seal assembly moves to the engaged position, it preferably sealingly engages the internal wall of the pipe, and when the slip assembly moves to the expanded position, it preferably frictionally engages the internal wall of the pipe to prevent axial movement of the pipeline plug within the pipe. If pressure of fluid within the pipe and the force exerted by the fluid on the pressure engaging surface increases, the force by which the outer surface of the slip assembly frictionally engages the internal wall of the pipe also preferably increases.

In another embodiment, a pipeline plug includes a plug body with a head and a shaft coupled to the head. The head has a pressure engaging surface. The shaft has external threads and internal threads that are threaded in an opposite direction as the external threads. A set ring has internal threads that engage the external threads of the shaft. A plurality of slips are coupled to the set ring. A seal is positioned between the head and the plurality of slips, and a cone is positioned between the seal and the set ring. The cone has a slip engaging surface that engages the plurality of slips. Each of the plurality of slips, the seal, and the cone presents an opening that receives the shaft. Preferably, the plug body is rotated in a first direction to move it from a disengaged position to an engaged position, in which it may sealingly engage the internal wall of a pipe within which the pipeline plug is positioned. As the plug body moves to the engaged position preferably the slip engaging surface moves an outer surface of the plurality of slips from a retracted position to an expanded position, in which it may frictionally engage the internal wall of the pipe. The plug body preferably may be rotated in a second direction, opposite to the first direction, to move the plug body from the engaged position to the disengaged position and to move the plurality of slips to the retracted position so that the pipeline plug may be removed from the pipe.

The present application also encompasses a method of sealing a pipeline with a pipeline plug having a seal assembly with a pressure engaging surface and a slip engaging surface. The pipeline plug also has a slip assembly with an outer surface. The method includes sliding the pipeline plug into a pipe, and rotating at least a portion of the seal assembly in a first direction with respect to the slip assembly to move the seal assembly from a disengaged position to an engaged position. Movement of the seal assembly from the disengaged position to the engaged position causes the slip engaging surface to move the outer surface from a retracted position to an expanded position, in which the outer surface engages the pipe. Next, at least a portion of the seal assembly is rotated in a second direction that is opposite to the first direction with respect to the slip assembly to move the seal assembly from the engaged position to the disengaged position. Movement of the seal assembly from the engaged position to the disengaged position allows the outer surface to move from the expanded position to the retracted position. Finally, the pipeline plug slides out of the pipe.

The pipeline plugs set forth above may preferably be used to seal an oil pipeline branch for the replacement or repair of a valve connected to the oil pipeline branch. The pipeline plugs are preferably set in place within the oil pipeline branch using a conventional drilling machine and tools adapted for use with the drilling machine. When the pipeline plug is set in place, it holds back the fluid within the oil pipeline branch so that the valve may be repaired or replaced. After repair or replacement of the valve, the pipeline plug may be removed from the pipe without damaging the pipeline plug, the oil pipeline branch or the valve. Thus, the pipeline plug may be reused multiple times.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A pipeline plug in accordance with one embodiment of the invention described herein is identified generally as10inFIG. 1. Pipeline plug10includes a seal assembly12and a slip assembly14that is coupled to the seal assembly12. As described in detail below, the pipeline plug10may be used to plug an oil pipeline branch to facilitate the replacement or repair of a valve on the oil pipeline branch. Pipeline plug10may also be used to plug pipes for other purposes. The pipeline plug10is set in place by sliding it through the oil pipeline branch and valve. The seal assembly12is then moved in one direction relative to the slip assembly14, which expands the seal assembly12causing it to sealingly engage the internal wall of the oil pipeline branch and which expands the slip assembly14causing it to engage the internal wall of the oil pipeline branch. The pipeline plug10holds back fluid within the oil pipeline branch as the valve is repaired or replaced. The force exerted on the pipeline plug10by the pressurized fluid within the oil pipeline branch causes the seal assembly12to exert a force on the slip assembly14that resists contraction of the slip assembly14. After the valve is repaired or replaced, the seal assembly12may then be moved in the opposite direction relative to the slip assembly14to contract the seal assembly12and slip assembly14allowing the pipeline plug10to slide back out of the oil pipeline branch and valve. The pipeline plug10is not damaged during usage so that it may be reused after it slides out of the oil pipeline branch and valve.

Referring toFIG. 2, seal assembly12includes a plug body16, a washer18, a seal20, and a cone22. Plug body16is generally shaped like a bolt with a head24and a shaft26that is coupled to head24. Head24has an outer diameter that is greater than the outer diameter of shaft26to form an abutment surface28. Head24has a pressure engaging surface30that is exposed to the pressurized fluid within a pipe when pipeline plug10is deployed. Shaft26includes an outer surface32, a portion of which has external threads34formed therein. External threads34extend from the opposite end of plug body16as the end with head24toward head24about one third of the length of shaft26.

Shaft26includes a cylindrical recess36that extends into shaft26from the opposite end of plug body16as the end with head24. Cylindrical recess36extends into shaft26a distance that is approximately one half of the length of external threads34. An internal surface38surrounds cylindrical recess36. Internal surface38includes internal threads40. Internal threads40are threaded in an opposite direction as the external threads34. Internal threads40may be left hand threaded and external threads34may be right hand threaded, or internal threads40may be right hand threaded and external threads34may be left hand threaded.

A pin42is positioned within cylindrical recess36and has a length that is approximately one half of the total length of cylindrical recess36. An annular groove44is formed in the outer surface32of shaft26. Annular groove44is positioned between external threads34and cone22. A spiral retaining ring46is received by annular groove44.

Washer18includes a central opening48that receives shaft26. Washer18has a cylindrical outer surface50with a diameter that is approximately the same as the diameter of head24. Washer18abuts the abutment surface28of head24, and is positioned between head24and seal20.

Seal20includes a central opening52that receives shaft26. Seal20has a cylindrical outer surface54with a diameter when seal20is uncompressed, as shown inFIG. 2, that is slightly larger than the diameter of head24. Seal20has a length that extends approximately one third of the length of shaft26. Seal20is positioned between washer18and cone22. Seal20is preferably formed from a fluoroelastomer material, such as 75 durometer fluoroelastomer material sold under the trademark VITON by The Chemours Company; however, it is within the scope of the invention for seal20to be formed from any suitable elastomer or other material.

Cone22includes a central opening56that receives shaft26. Cone22includes a first end58that is positioned nearest to a set ring60of slip assembly14and a second end62that is positioned nearest to head24. Cone22has a tapered outer surface64that increases in diameter from first end58to a location approximate second end62where the diameter is constant from there to second end62. The diameter of tapered outer surface64at first end58is slightly larger than the diameter of shaft26, and the diameter of tapered outer surface64near second end62is approximately the same as the diameter of seal20when uncompressed. Tapered outer surface64acts as a slip engaging surface that engages a plurality of slips66of slip assembly14. Cone22is positioned around shaft26between seal20and spiral retaining ring46.

To assemble seal assembly12, washer18, seal20, and cone22are preferably received by and slide down shaft26before spiral retaining ring46is placed within annular groove44to retain washer18, seal20, and cone22on shaft26.

Referring toFIG. 3, slip assembly14includes a plurality of slips66and set ring60, which is coupled to the plurality of slips66with a plurality of pins, one of which is identified as68. The plurality of slips66includes a cylindrical outer surface70, shown inFIG. 1, within which is formed a plurality of grooves, one of which is identified as72. The grooves72run lengthwise from an open end adjacent cone22to a closed end adjacent set ring60. The diameter of cylindrical outer surface70is approximately the same as the diameter of seal20when uncompressed. Cylindrical outer surface70transitions to an inclined surface74that increases in diameter moving from cylindrical outer surface70toward cone22. Inclined surface74transitions to a serrated outer surface76, which transitions to an inclined surface78that decreases in diameter moving from serrated outer surface76towards cone22. Referring toFIG. 5, serrated outer surface76includes a plurality of teeth, one of which is identified as80, that each extend circumferentially around serrated outer surface76. Tooth80includes an inclined surface82that increases in diameter moving from inclined surface78toward inclined surface74. Tooth80includes a face84that extends from an edge of the tooth80at the end of inclined surface82to the beginning of the inclined surface of the next tooth in the serrated outer surface76. The plurality of slips66includes an internal opening86(FIG. 3) that is larger than shaft26and that is received by shaft26. Surrounding internal opening86near serrated outer surface76, the plurality of slips66includes an internal inclined surface87that is adapted to abut and engage the tapered outer surface64of cone22, as shown inFIG. 3.

Set ring60, shown inFIG. 4, includes a cylindrical outer surface88with an outer diameter that is slightly smaller than the diameter of the internal opening86of the plurality of slips66. Set ring60includes a flange90extending from the cylindrical outer surface88. Flange90has an outer diameter that is approximately the same as the outer diameter of the plurality of slips66. Set ring60includes an internal opening92that extends through the set ring60. A cylindrical surface surrounding the internal opening92includes internal threads94. Internal threads94are threaded in the same direction as the external threads34of plug body16and in the opposite direction as the internal threads40of plug body16. Internal threads94and external threads34are preferably right hand threaded, while internal threads40of plug body16are preferably left hand threaded. Internal opening92receives shaft26and internal threads94engage the external threads34of plug body16, as shown inFIG. 3.

Cylindrical outer surface88of set ring60includes a plurality of openings, one of which is identified as96inFIG. 4. The plurality of openings96in set ring60are spaced apart the same distance as the distance between the plurality of grooves72in the plurality of slips66. Pins68(FIG. 3) are received by the plurality of grooves72and plurality of openings96to couple the plurality of slips66with set ring60. Cylindrical outer surface88is positioned within the plurality of slips66and flange90abuts the end of the plurality of slips66, as shown inFIG. 3.

Seal assembly12, including plug body16, is movable with respect to slip assembly14between an engaged position, shown inFIG. 3, and a disengaged position, shown inFIG. 9B. Plug body16moves from the engaged position to the disengaged position by rotating the plug body16with respect to the set ring60in a first direction, which is clockwise when viewing pipeline plug10from the end of set ring60and when the internal threads94of set ring60and the external threads34of plug body16are right hand threaded. Plug body16moves from the disengaged position to the engaged position by rotating the plug body16with respect to the set ring60in a second direction that is opposite to the first direction. The second direction is counter-clockwise when viewing pipeline plug10from the end of set ring60and when the internal threads94of set ring60and the external threads34of plug body16are right hand threaded.

The serrated outer surface76of the plurality of slips66is movable between a retracted position, shown inFIG. 9B, and an expanded position, shown inFIG. 3. The serrated outer surface76is in the retracted position when plug body16is in the disengaged position. When plug body16moves from the disengaged position to the engaged position, the tapered outer surface64of cone22engages the internal inclined surface87of the plurality of slips66. This engagement causes the serrated outer surface76of the plurality of slips66to move from the retracted position to the expanded position. In the retracted position and when a force is applied to the serrated outer surface76causing it to move inward toward shaft26, the serrated outer surface76has an outer diameter that is approximately the same as the outer diameter of the head24of plug body16. In the expanded position, the serrated outer surface76has a diameter that expands to be greater than the diameter of head24of plug body16enabling the serrated outer surface76to engage and grip the internal wall of a pipe within which pipeline plug10is positioned. The teeth of serrated outer surface76, shown inFIG. 5, are configured to frictionally engage the internal wall of a pipe to prevent pipeline plug10from being moved axially within the pipe due to a force exerted on the pipeline plug10from the fluid within the pipe. Further, when plug body16is in the disengaged position, the outer diameter of seal20is slightly larger than the diameter of head24. When plug body16is in the engaged position, the seal20is compressed between the washer18and cone22, which causes the outer diameter of seal20to expand, as shown inFIG. 3, and be substantially greater than the diameter of head24so that the seal20sealingly engages the internal wall of a pipe within which pipeline plug10is positioned.

When the serrated outer surface76is in the retracted position, it preferably has an outer diameter that is slightly larger than the internal diameter of the pipe that pipeline plug10is designed to seal. For example, if pipeline plug10is designed for sealing a pipe having an internal diameter of 0.75 inches, serrated outer surface76may have an outer diameter of approximately 0.80 inches when in the retracted position. By having an outer diameter that is slightly larger than the internal diameter of the pipe, the plurality of slips66are slightly compressed inward when pipeline plug10is inserted axially through an opening in the end of the pipe. The plurality of grooves72allow the plurality of slips66to be compressed inward in this manner. When pipeline plug10is positioned within the pipe and the inner surface of the pipe compresses the plurality of slips66inward, the plurality of slips66exert a resultant force on the inner surface of the pipe. The plurality of slips66are designed so that this resultant force prevents rotation of the plurality of slips66within the pipe as the plug body16is rotated with respect to set ring60to move plug body16from its disengaged position to its engaged position.

When a force is exerted on the pressure engaging surface30(FIG. 3) of plug body16, such as a force resulting from pipeline plug10holding back pressurized fluid within a pipe, the force is transferred through the head24of plug body16, washer18, seal20, and cone22. The force is then transferred from the tapered outer surface64of cone22to the internal inclined surface87of the plurality of slips66. The force exerted on the internal inclined surface87is substantially perpendicular to the internal inclined surface87and thus opposes movement of the serrated outer surface76from the expanded position to the retracted position. The force also presses the serrated outer surface76into tighter frictional engagement with the internal wall of a pipe, which allows pipeline plug10to hold back fluid within the pipe at a greater pressure without pipeline plug10moving axially within the pipe. When a force is exerted on the pressure engaging surface30, the plug body16is movable from the engaged position to the disengaged position to move the serrated outer surface76from the expanded position to the retracted position. As plug body16moves from the engaged position to the disengaged position, spiral retaining ring46engages the first end58of cone22to move the cone22away from the plurality of slips66, which allows the serrated outer surface76to move from the expanded position to the retracted position. Thus, even when a force is exerted on pressure engaging surface30, pipeline plug10is removable from a pipe by moving plug body16to the disengaged position.

Referring toFIGS. 6A and 6B, a set tool for use in setting pipeline plug10within a pipe is identified generally as98. Set tool98includes an adapter100that is coupled to a plug engager102with a pin104. Adapter100includes external threads106on one end that are preferably adapted for engagement by a drilling machine, such as the Mueller E-5 drilling machine sold by Mueller Co. Adapter100includes a head108with generally parallel tool engaging surfaces110that can be engaged by a wrench to join adapter100to a drilling machine. At the opposite end as external threads106, adapter100includes an internal recess112that receives a portion of plug engager102. Grooves114formed in an outer surface of adapter100extend into the internal recess112. Plug engager102includes an opening116at one end that is aligned with the grooves114. Pin104is received by the grooves114and opening116to couple adapter100to plug engager102. At the opposite end of plug engager102as opening116, plug engager102has a shaft with external threads118. The external threads118of plug engager102are preferably sized for engagement with, and are threaded in the same direction as, the internal threads40of plug body16. Preferably, the external threads118of plug engager102and the internal threads40of plug body16are left hand threaded. When the external threads118of set tool98are left hand threaded and engage the internal threads40of plug body16, the set tool98is rotated in a counter-clockwise direction (when viewing pipeline plug10from the end of set ring60) to move the set tool98inward toward pin42. When set tool98engages pin42, further rotation of set tool98in the counter-clockwise direction causes the plug body16to move from the disengaged position to the engaged position via the threaded engagement between the external threads34of plug body16and the internal threads94of set ring60, each of which being right-hand threaded in this example.

A release tool for use in releasing pipeline plug10from engagement with a pipe is identified generally as120inFIGS. 7A and 7B. Release tool120includes an adapter122that is coupled to a plug engager124with a pin126. Adapter122preferably has a similar configuration as the adapter100of set tool98described above. Thus, adapter122is not described in detail herein. Plug engager124includes one end with an opening128that receives pin126to couple plug engager124to adapter122in a similar manner as described above with respect to the coupling of adapter100and plug engager102of set tool98. Plug engager124includes a shaft130that is partially received by the recess in adapter122. An end of shaft130spaced apart from adapter122is received by a recess132in a removal tool collar134. Removal tool collar134is preferably joined to shaft130. An end of removal tool collar134opposite recess132includes an opening136that is surrounded by an internal surface with internal threads138. Internal threads138of release tool120are preferably sized for engagement with, and are threaded in the same direction as, the external threads34of plug body16. Preferably, the internal threads138of release tool120and the external threads34of plug body16are right hand threaded. When the internal threads138of release tool120are right hand threaded and engage the external threads34of plug body16, the release tool120is rotated in a clockwise direction (when viewing pipeline plug10from the end of set ring60) to move the release tool120inward toward set ring60. When release tool120engages set ring60, further rotation of release tool120in the clockwise direction causes the plug body16to move from the engaged position to the disengaged position via the threaded engagement between the external threads34of plug body16and the internal threads94of set ring60.

Referring toFIG. 8A, a spring reamer for reaming the inner wall of a pipe prior to insertion of pipeline plug10is identified generally as140. Spring reamer140includes shaft142with an opening144. A cylinder146extends outward from the shaft142, a first inclined surface148extends outward from the cylinder146, a cylindrical surface150extends outward from the first inclined surface148, and a second inclined surface152extends outward from the cylindrical surface150. A plurality of grooves154are formed in the outer surfaces of the cylinder146, first inclined surface148, cylindrical surface150, and second inclined surface152. The grooves154extend from an end of the spring reamer140containing second inclined surface152toward shaft142and terminate prior to shaft142. Cylinder146, first inclined surface148, cylindrical surface150, and second inclined surface152surround a hollow interior. First inclined surface148increases in diameter moving from shaft142toward cylindrical surface150, and second inclined surface152decreases in diameter moving from cylindrical surface150toward the end of spring reamer140. The diameter of cylindrical surface150is preferably sized for reaming the inner diameter of a particular size of pipe.

FIG. 8Bshows a reamer adapter156that couples to spring reamer140for joining the spring reamer140to a drilling machine. Reamer adapter156includes external threads158on one end that are preferably adapted for engagement by a drilling machine, such as the Mueller E-5 drilling machine sold by Mueller Co. Reamer adapter156includes a head160with generally parallel tool engaging surfaces162that can be engaged by a wrench to join reamer adapter156to a drilling machine. At the opposite end as external threads158, reamer adapter156includes an internal recess164that receives a portion of spring reamer140. An opening166in reamer adapter156receives a pin (not shown) that is also received by the opening144in spring reamer140to couple spring reamer140to reamer adapter156.

In operation, prior to deployment of pipeline plug10within a pipe, the pipe is first configured so that a drilling machine may be used to advance and rotate the pipeline plug10within the pipe. If the pipe is a 0.75 inch or 1 inch oil pipeline branch, a Mueller E-5 drilling machine is preferably used to advance and rotate the pipeline plug10within the pipe. To prepare the pipe for use with the Mueller E-5 drilling machine, a Mueller threaded adapter168(FIG. 9C) is threaded into engagement with the pipe.FIG. 9Cshows Mueller threaded adapter168threaded into engagement with the opening of a valve170that is threaded into engagement with an oil pipeline branch172. A bleed valve174is joined to the Mueller threaded adapter168.

Prior to setting of the pipeline plug10, spring reamer140may be used to clear debris from within the oil pipeline branch172and prepare it to be plugged. Spring reamer140is joined to reamer adapter156, and reamer adapter156is joined to the boring bar176(FIG. 9A) of a Mueller E-5 drilling machine178in a conventional fashion. The boring bar176and spring reamer140are retracted into the body180of the drilling machine178in a conventional manner, and the body180is threaded into engagement with the threaded adapter168, as shown inFIG. 9D. The boring bar176and spring reamer140are then advanced into the oil pipeline branch172by coupling feed tube182and boring bar176of the drilling machine178with yoke184, in the conventional manner as shown inFIG. 9E. Bleed valve174is closed and valve170is opened. Feed tube182is rotated to move it down body180and advance spring reamer140into oil pipeline branch172. Boring bar176is simultaneously rotated at the top of the drilling machine178to rotate spring reamer140within the oil pipeline branch172. Spring reamer140reams the interior surface of the oil pipeline branch172as spring reamer140is advanced into oil pipeline branch172. When the spring reamer140has advanced through the oil pipeline branch172, feed tube182is rotated in the opposite direction to back spring reamer140out of the oil pipeline branch172while continuing to rotate the boring bar176and spring reamer140. The valve170is closed and bleed valve174is opened to depressurize the drilling machine178. Drilling machine178is then disengaged from threaded adapter168and reamer adapter156is disengaged from boring bar176. Other types of reamers and drill bits may be used with the Mueller E-5 drilling machine178to clear debris from within oil pipeline branch172prior to deployment of pipeline plug10within oil pipeline branch172.

Oil pipeline branch172is sealed with pipeline plug10by first sliding the pipeline plug10into the oil pipeline branch172. This is accomplished by attaching set tool98(FIG. 6A) to boring bar176with external threads106of set tool98engaging boring bar176. The internal threads40(FIG. 2) of plug body16are then engaged with the external threads118of set tool98, and plug body16is rotated with respect to set tool98to screw the pipeline plug10into engagement with set tool98. If internal threads40of plug body16are left hand threaded, counter-clockwise rotation of plug body16(when viewing plug body16from the end with head24) tightens the pipeline plug10on set tool98. Slip assembly14is then rotated with respect to seal assembly12to move slip assembly14away from cone22into the position shown inFIG. 9Badjacent set tool98. This ensures that the plurality of slips66will remain in the retracted position as the pipeline plug10slides into the oil pipeline branch172.

The boring bar176and pipeline plug10are next retracted into the body180of the drilling machine178, and the drilling machine178is engaged with the threaded adapter168, as shown inFIG. 9D. Yoke184is engaged with the boring bar176, bleed valve174is opened, and feed tube182is rotated, while rotation of boring bar176is restricted, until pipeline plug10makes contact with the closed valve170to be replaced. Bleed valve174is closed and valve170is opened. Feed tube182is rotated clockwise (when viewing the top of boring bar176) to advance boring bar176and pipeline plug10down through valve170and into oil pipeline branch172to the position shown inFIG. 9E. The boring bar176and pipeline plug10are advanced a desired distance until pipeline plug10is positioned within oil pipeline branch172. The distance may be measured and marked on body180prior to advancement of boring bar176. Feed tube182is then rotated in the opposite direction to retract the boring bar176upward by approximately 0.75 inches. Boring bar176is then rotated counter-clockwise (when viewing the top of boring bar176), which causes set tool98and plug body16to rotate with respect to set ring60advancing cone22toward the plurality of slips66. As set tool98and plug body16rotate, plug body16moves from the disengaged position (FIG. 9B) to the engaged position (FIG. 3) and the serrated outer surface76of the plurality of slips66moves from the retracted position to the expanded position. As described above, serrated outer surface76preferably has an outer diameter that is slightly larger than the internal diameter of oil pipeline branch172such that the plurality of slips66exert a force on the internal surface of the oil pipeline branch172that prevents rotation of the plurality of slips66as plug body16is rotated. In the expanded position, the serrated outer surface76engages the internal surface of the oil pipeline branch172to prevent axial movement of the pipeline plug10within the oil pipeline branch172. As the plug body16moves from the disengaged position to the engaged position, the outer diameter of seal20also expands to sealingly engage the internal surface of the oil pipeline branch172so that fluid cannot move past the pipeline plug10. In this manner, pipeline plug10seals the oil pipeline branch172.

With pipeline plug10sealing the oil pipeline branch172, valve170may be repaired or replaced. To replace valve170, bleed valve174is first opened to relieve the pressure within drilling machine178. Boring bar176is then rotated in a clockwise direction (when viewing the top of boring bar176), which causes set tool98to disengage the internal threads40(FIG. 2) of plug body16. While rotating boring bar176, the yoke184and feed tube182(FIG. 9E) are simultaneously rotated in a counter-clockwise direction to move the boring bar176and set tool98upward with respect to pipeline plug10. When set tool98and boring bar176are retracted into the body180of drilling machine178, valve170is closed and drilling machine178is disengaged from the threaded adapter168. Threaded adapter168may then be disengaged from valve170, and valve170may be disengaged from oil pipeline branch172for repair or replacement.FIG. 9Fshows oil pipeline branch172with valve170disengaged and removed. Pipeline plug10is positioned within and seals oil pipeline branch172to prevent the flow of fluid out of oil pipeline branch172.

To put oil pipeline branch172back in service, valve170is repaired and rethreaded into engagement with oil pipeline branch172, or a new valve170is threaded into engagement with oil pipeline branch172. To remove the pipeline plug10from oil pipeline branch172, valve170is closed and threaded adapter168is threaded into engagement with valve170. Set tool98is disengaged from the boring bar176of drilling machine178and release tool120is threaded into engagement with the boring bar176. The boring bar176and release tool120are then retracted into the body180of the drilling machine178, and the drilling machine178is engaged with the threaded adapter168, as shown inFIG. 9D. Valve170is opened. Yoke184is engaged with the boring bar176, and feed tube182is rotated, while rotation of boring bar176is restricted, to advance the boring bar176and release tool120through valve170to the position shown inFIG. 9Euntil release tool120makes contact with plug body16. Bleed valve174is closed. Boring bar176is rotated in a clockwise direction (when viewing the top of the boring bar176) so that the internal threads138of release tool120engage the external threads34of plug body16. As boring bar176is rotated, the release tool120moves downward toward the set ring60. When release tool120engages set ring60, further rotation of boring bar176and release tool120in the clockwise direction causes the plug body16to move from the engaged position (FIG. 3) to the disengaged position (FIG. 9B) and the serrated outer surface76of the plurality of slips66to move from the expanded position to the retracted position as spiral retaining ring46engages cone22to move cone22away from the plurality of slips66. As the plug body16moves from the engaged position to the disengaged position, seal20contracts so that it no longer sealingly engages the internal wall of oil pipeline branch172. This allows fluid to flow past pipeline plug10into the drilling machine178. When serrated outer surface76moves to the retracted position, it no longer frictionally engages the internal wall of oil pipeline branch172so that pipeline plug10may be moved axially within oil pipeline branch172.

To slide pipeline plug10out of the oil pipeline branch172, feed tube182and yoke184are rotated in a counter-clockwise direction (when viewing the top of boring bar176). This rotation moves the boring bar176, release tool120, and pipeline plug10upward through the oil pipeline branch172, valve170, and threaded adapter168. Valve170is then closed, and bleed valve174is opened to release pressure from within drilling machine178. Drilling machine178is then rotated to disengage it from threaded adapter168, and threaded adapter168is disengaged from valve170. The pipeline plug10may be disengaged from the release tool120and reused in future plugging operations. The pipeline plug10is not damaged during conventional use, which enables its reuse.

Other types of drilling machines besides the Mueller E-5 drilling machine178may be used to set pipeline plug10within a pipe. For instance, a T-101 drilling machine sold by T.D. Williamson may be used to set pipeline plug10within a pipe. The process for setting pipeline plug10with a T-101 drilling machine is similar to the process for setting pipeline plug10with a Mueller E-5 drilling machine; however, the set tool and release tool for use with the T-101 drilling machine are adapted for connection to the T-101 drilling machine and thus have a slightly different configuration than the set tool98and release tool120described above for use with the Mueller E-5 drilling machine178.

The components of pipeline plug10may be sized for use with pipes of different dimensions, including, but not limited to, Schedule 80 pipes having internal diameters of approximately 0.75 inches, 1 inch, or 2 inches. Further, a particular size of pipeline plug10can be used to sealingly engage pipes within a range of internal diameters due to the variable expansion of seal20and the plurality of slips66as plug body16moves from the disengaged position to the engaged position when the seal20sealingly engages the internal wall of the pipe and the serrated outer surface76of the plurality of slips66engages the internal wall of the pipe to prevent axial movement of the pipeline plug10within the pipe. Pipeline plug10may also be used to sealingly engage a pipe having a varying internal diameter due to manufacturing inconsistencies and/or debris adhered to the internal wall of the pipe. The resilient nature of seal20and the grooves72separating portions of the serrated outer surface76allow pipeline plug10to seal a pipe having a varying internal diameter.

Pipeline plug10is preferably capable of sealing a pipe containing fluid at a pressure of 500 psi, and is most preferably capable of sealing a pipe containing fluid at a pressure of 5000 psi.

From the foregoing it will be seen that this invention is one well adapted to attain all ends and objectives herein-above set forth, together with the other advantages which are obvious and which are inherent to the invention.

Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative, and not in a limiting sense.

While specific embodiments have been shown and discussed, various modifications may of course be made, and the invention is not limited to the specific forms or arrangement of parts and steps described herein, except insofar as such limitations are included in the following claims. Further, it will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.