A system and method of plugging a pipe including sealably securing onto the exterior of a pipe first and second spaced apart collars, each collar having a sealing face in a plane perpendicular the pipe axis, cutting and removing a length of pipe from between the collars leaving two open pipe ends, positioning first and second seal cups between the collars, each seal cup having a forwardly extending circumferential lip of internal diameter greater than the external diameter of the pipe, each seal cup having top and bottom cam followers, moving cam surfaces against the cam followers to guide the seal cups into sealing engagement with the sealing faces of the collars, and forcing a wedge between rearward surfaces of the seal cups.

REFERENCE TO PENDING APPLICATIONS

This application is not based upon any pending domestic or international patent applications.

REFERENCE TO MICROFICHE APPENDIX

This application is not referenced in any microfiche appendix.

FIELD OF THE INVENTION

This invention relates to apparatus systems and methods for plugging a pipe or pipeline having high temperature liquids or gases flowing therethrough.

BACKGROUND OF THE INVENTION

This invention relates to cam guided systems and methods for plugging a pipe under pressure, and is particularly applicable for plugging a pipe, or pipeline having therein high temperature liquids or gases. “Pipe” as used hereinafter is inclusive of any tubular member made of metal for carrying fluid (liquids or gases).

The invention described herein is a cam-assisted, wedge actuated, double block and bleed, metal-to-metal high temperature valve.

Tapping machines, such as the kind described in the above-mentioned U.S. patents, are for tapping a hole in a pipe while liquids or gases are flowing through them, that is, while the pipe is under pressure. Tapping procedures of this type are customarily carried out primarily for one of two purposes, that is, to provide a branch fitting on the pipe or to enable fluid flow through the pipe to be blocked. Other examples of prior art that describe and illustrate plugging the interior of a pipe usually associated with first tapping the pipe, include the following United States patents:

BRIEF SUMMARY OF THE INVENTION

The invention described herein is a cam-assisted, wedge actuated, double block and bleed, metal-to-metal, high temperature plugging tool.

The invention herein makes use of the known technology of welding onto a pipe having fluid flow therethrough a pair of collars. Each of the collars is a toroidal that is severed to provide a set of two toroidal halves that are fitted together around the pipe. Each collar set consisting of two spaced apart parallel collars are first secured to the exterior of the pipe. Each collar has a machined face which can be achieved by machining and grinding before the collars have been welded to the pipe. Thus a set of collars affixed to the exterior surface of a pipe provide forward planar faces that face each other. The collar faces are parallel to each other and spaced apart an accurately establish distance. After each collar is affixed to the pipe, the collar halves are then welded to each other. Further, the two halves of each collar are welded where the back face meets the pipe around the 360° circumference of the pipe. After the collars are installed, they provide uninterrupted circumferentially planar sealing surfaces that face each other. The sealing surfaces are parallel to each other and in radial planes perpendicular to longitudinal axis of the pipe.

After the collars are welded to the exterior surface of a pipe containment fittings are welded to the collars to provide a housing of internal dimensions greater than the external surface of the pipe. The containment housing has a bottom usually in the form of a cup-shaped member and a flange fitting at the upper end. After the containment housing, including the bottom member and the upper flange have been welded to the collars, the containment housing is typically pressure tested to ensure there are no leaks and that the collars and the containment housing have the structural integrity to contain the maximum pressure to which they will be subjected.

After the collars and the containment housing components have been installed and tested, a valve is secured to the containment housing flange. A tapping machine system, well known in the industry, is secured to the upper surface of the valve and then pressure is applied to test for leaks. Thereafter, by use of the tapping machine, a complete section of the pipeline is removed from between the collars. The concept of removing a complete section rather than tapping only a hole in the pipe is illustrated in U.S. Pat. No. 5,612,499 entitled “Method of Inserting A Sensor Into A Pipeline”. When a section of the pipeline has been cut, it is removed exposing the opposed ends of the cutout section of the pipeline, the exposed ends being surrounded by the collars that have previously been attached to the pipe.

After the collars and the containment housing have been affixed to the exterior of the pipe, and a tapping machine attached and a section of the pipe cut and removed, the next step is to seal the opposed ends of the pipe employing a plugging tool that is the subject of the present disclosure. The plugging tool is inserted as an assembly into the interior of the containment housing. The tool contains opposed sealing cups, each having a circumferential sealing surface of internal diameter greater than the external diameter of the pipe. The plugging tool assembly is lowered into the containment housing and actuated such that the opposed sealing cups are advanced in directions towards the open ends of a severed pipe and towards the opposed planar circumferential sealing surfaces provided by the collars.

The plugging tool assembly includes upper and lower cam followers affixed to each of the seal cups rearwardly of the forward faces thereof. Top and bottom supports each having a pair of cam slots for receiving the cam followers and are configured to urge the seal cups towards the toroidal sealing surfaces on the collars. The plugging tool assembly includes translation apparatus for moving the top and bottom supports toward and away from each other to thereby urge the seal cups towards and away from the toroidal collar sealing surfaces.

A pair of wedge members are forced against rearward surfaces of the seal cups to simultaneously force them into metal-to-metal sealing contact with the sealing surfaces formed on the toroidal collars. In this manner a double block and bleed, metal-to-metal seal, high temperature plugging tool is achieved. After the seal cups are forced into sealing condition the interior of the containment housing can be tested to verify that both seal cups are in leak-proof contact with the toroidal collars.

The sealing assembly is moved into or out of the containment housing by means of a hydraulic cylinder with a piston therein and a piston rod extending sealably from the hydraulic cylinder. The plugging tool assembly is supported by the piston rod. It is important that the plugging assembly be accurately positioned within the housing and therefore the piston rod that holds the assembly must be non-rotatably secured with respect to the housing. For this purpose, a type of hydraulic cylinder/piston assembly is provided in an arrangement that rotationally fixes the piston and piston rod with respect to the cylinder, that is, it allows the piston rod to be axially displaced relative to the cylinder but prevents the piston rod from rotating about its axis relative to the cylinder axis.

A better understanding of the invention will be obtained from the following detailed description of the preferred embodiments and claims taken in conjunction with the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the invention that is now to be described is not limited in its application to the details of the construction and arrangement of the parts illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. The phraseology and terminology employed herein are for purposes of description and not limitation.

Elements illustrated in the drawings are identified by the following numbers:

Referring to the drawings and first toFIG. 1, the first step in practicing the systems and methods of this invention is to affix a first collar, generally indicated by the number12to the exterior of pipe10. Then a second, spaced apart, collar14is affixed to the pipe. Each of collars12and14are made up of two semi-circular pieces. Each of the collars is geometrically shaped as a toroidal. While not seen in the drawings, collars12and14are each formed of an upper half and a lower half that are positioned on pipe10. The collar halves are then welded to each other and to the pipe10, the welds to pipe10being indicated by reference numeral16. InFIGS. 1 and 7, welds16are shown only on exterior faces of collars12and14although interior welds can in like manner be applied. Welds16extend around the full interior of the toroidal collars12and14and around the complete external circumference of pipe10. In addition, though not seen in the drawings, the upper and lower halves of each of the collars12and14are welded to each other so that the collars12and14become unitary. The collars are spaced apart from each other at an accurately determined distance and are each in a radial plane perpendicular of the longitudinal axis of pipe10.

Collar12has an inner face18that is circumferential and uninterrupted around pipe10and second collar14has a matching circumferential inner face20. In the practice of this invention it is important that the inner faces18and20be parallel to each other and spaced apart an accurate pre-determined distance. For this reason, a cradle-like structure (not shown) can be used to support the upper and lower halves of each of the collars as they are being positioned on and secured to the pipe.

After collars12and14have been accurately positioned and welded to pipe10, a containment housing is affixed to the external circumferential surface22of collar12and the matching external circumferential surface24of collar14. This housing typically consists of a lower containment housing portion26and a mating upper containment housing portion28. These upper and lower containment housing portions are secured to collars12and14by welds30and the collar portions are welded to each other. To close the open bottom of lower containment housing portion26an end cap32is employed, the end cap being welded to the lower containment housing portion26by a circumferential weld34. In a similar manner, the open upper containment housing portion28receives a flange member36, the flange being secured to the upper containment housing portion28by a circumferential weld38. The flange member36has a passageway40therethrough.

With collars12and14in place, with the upper and lower containment housing portions26and28welded to them and with end cap32and flange member36welded to the housing portions, a short section of the length of pipe10is fully enclosed.

After the components that have been described are in place as illustrated inFIGS. 1 and 7, the next step in preparing the pipe to be closed is to remove a section of the pipe. This is accomplished by attaching a tapping machine (not shown) to the upper surface45of flange36using a procedure that is known in the industry. A tapping machine has provision for guiding a circular saw down through the passageway40to engage pipe10. The circular saw cuts out a section of pipe10leaving the pipe ends42and44exposed. The removed section of the pipe10is extracted from within the housing. The pipe is then ready to be closed off by employing a pipe sealing assembly of this invention that will now be described.

Looking first atFIG. 3, the pipe sealing assembly46includes first and second wedge members48and50that are held together at the top by a plate52and, at the bottom, by a lower support54that has a portion extending between the lower ends of the wedge members and as best seen inFIGS. 4B,5and6.

As seen inFIGS. 4,5,6and7an elongated shaft56extends between wedge members48and50. Shaft56is threaded at its lower end and engages a threaded opening58in the top of lower support54. A shaft guide60has a central opening therethrough slidably receiving shaft56, the shaft guide being secured by bolts to an upper surface of top plate52. Slidably positioned between wedge members48and50is a top support62that, as seen inFIG. 7, has a passageway64therethrough that slidably receives shaft56.

Positioned with respect to wedge members48and50is a first seal cup66and an opposed second seal cup68. As seen inFIG. 4B, seal cup66has upwardly extending arms70that support a first roller72. Seal cup68has upwardly extending arms70that supports a second roller74.

First seal cup66has downwardly extending arms76that support a lower roller78and second seal cup68has similar downwardly extending arms that support a lower roller80.

Lower support54has a pair of cam slots82and84that receives lower rollers78and80respectfully. In like manner, top support62has a pair of cam slots86and88that receives upper rollers72and74respectfully. It can be seen that when top support62is moved in a direction towards lower support54that rollers72,74,78and80acting in cam slots82,84,86and88serves to deflect seal cups66and68away from each other and contrarily when top support62moves away from lower support54the action between the rollers and cam slots retract the seal cup towards each other. Seal cups66and68are resiliently restrained towards each other by springs90as illustrated inFIG. 4B. Springs90are not shown inFIG. 3.

Received on shaft56and compressibly positioned between lower support54and top support62is a compression spring90. The downward translation of shaft guide60and thereby top plate52and with it, first and second wedge members48and50, forces the top support62towards lower support54, compressing spring90and moving the top rollers72and74within the cams formed in top support62and the bottom rollers78and80within the cams formed in lower support54. This cam action causes first and second seal cups66to displace outwardly with respect to each other. The downward movement of lower support54is limited by a stop post92affixed to the interior of end cap32as shown inFIGS. 7 and 8B.

First seal cup66has a front surface94having therein a circumferential recess96. In like manner, second seal cup68has a front surface98with a circumferential recess100. The function of recesses96and100is to receive the outer pipe ends42and44as the seal cups66and68are expanded outwardly. This allows a circumferential sealing surface102on cup66and a corresponding circumferential sealing surface104on the front face of seal cup68to engage first collar inner face18and second collar inner face20respectfully to form metal-to-metal seals. The circumferential metal-to-metal seal of first seal cup66against first collar inner face18closes the end42of pipe10and correspondingly, the circumferential metal-to-metal seal of second seal cup68against second collar inner face20closes the end44of pipe10. Thus when the seals66and68are expanded away from each other, they close both exposed ends of pipe10in a metal-to-metal sealing arrangement effectively blocking fluid flow through the pipe. This achieves a double block and bleed plugging arrangement. With both seal cups66and68in simultaneous sealed conditions as shown inFIG. 7the interior of the containment housing can be tapped to verify that both seal cups are in leak-proof closure.

Affixed to opposite sides of top support62are opposed brackets106, each having an axle with a pair of rollers108. Rollers108roll against the back surfaces110(seeFIG. 2) of each of wedge members48and50. Brackets106and rollers108are seen inFIGS. 2,3and4B. Only one bracket and one roller are seen inFIG. 3.

Affixed to the forward surface112of each of the wedge members48and50is a divider guide114. Affixed to each of the seal cups66and68are a pair of runners116, thereby being four runners116. Each pair of runners116is engaged by a divider guide114as the wedge members48and50are moved downwardly during the process of installing pipe sealing assembly46within a housing between exposed pipe ends42and44. Thus, the interaction of the divider guides114and runners116initiate displacement of seal cups66and68away from each other. The cam action provided by the cam slots formed in lower support54and top support62further assist in guiding the seal cups between their tool open and tool closed positions.

Lower support54that has cam slots82and84therein, has, shown integrally formed with it, a horizontal guide disc118. Secured to the bottom of the guide disc is a guide ring120. The guide disc/guide ring combination serves to guide the lower end of the assembly46as it is positioned within the housing and between the ends42and44of pipe10. Further, there is recess122formed in the bottom of guide disc118and guide ring120. Recess122receives stop post92when the assembly is forced downward into the housing. Stop post92defines the lower limit of travel of assembly46so that continued downward movement of guide60and with it wedge members48and50force upper rollers72and74to move within cam slots86and88and lower rollers78and80to move within cam slots82and84to guide seal cups66and68to move radially apart and towards their sealed positions as shown inFIG. 7.

The translation of seal cups66and68from their open positions as shown inFIG. 5to their closed positions as shown inFIGS. 6 and 7is achieved by four separate but cooperative actions. First is the action of divider guides114against runners116. Second, the bottom ends of wedge members48and50engage the top edges of the rearward surfaces of the seal cups to urge them apart. Third, the action of cam surfaces formed in lower support54and top support62guide the displacement of the seal cups away from each other. Fourth, the wedge surfaces of wedge member48and50slide against the rearward surfaces of seal cups66and68forcing the seal cup into metal-to-metal sealing relationship with the toroidal collars12and14as seen inFIG. 7. The first, second and third actions listed herein are primarily guiding actions. The actual sealing forces of the seal cups against the toroidal collars are achieved by the action of the wedge members48and50against the rearward surfaces of the sealing cups.

Referring toFIGS. 8A and 8B, the systems and methods that are employed in the insertion of pipe sealing assembly46into and removing it out of the containment housing surrounding pipe10is illustrated. As shown inFIG. 8B, there is affixed to the upper surface45of flange member36a valve124that has a lower flange126and an upper flange128. Lower flange126is secured to the upper surface45of flange member36. Valve124functions to open and close passageway130therethrough to enable different operating systems to be inserted into or removed from the interior of the containment housing surrounding pipe10. The internal working portions of valve124are not shown but the use of valves in systems for tapping pipelines under pressure are well known.

An adaptor casing132has a lower flange134that is secured to plugging tool upper flange128. Further, adaptor casing132has an upper flange136seen inFIG. 8A. Secured to upper flange136is a hydraulic cylinder adaptor138and secured to a hydraulic cylinder140that receives therein a slidable piston142. The upper end of hydraulic cylinder140receives closure member144.

Affixed to piston142is a piston rod146that extends to a sealable opening148in adaptor138. The lower end of piston rod146is attached to the upper end of a tubular piston rod extender150, the lower end of which is secured to the pipe sealing assembly top plate52. In this manner, insertion or removal of pipe sealing assembly46is controlled by the actuation of piston142and thereby piston rod146.

It is important that pipe sealing assembly46be accurately rotationally positioned with respect to the pipe ends42and44when it is inserted within the containment housing so that the seal cups66and68will properly align to form a sealing relationship with collars12and14. Normally a piston and piston rod operating within a cylinder have no means for maintaining rotational relationship with the cylinder. To alleviate this problem and to provide for accurate alignment of the pipe sealing assembly when it is inserted into a containment housing to seal the opposed ends of a pipe, the cylinder140and piston142of this invention operate in a system that ensure their rotational relationship. For this purpose there is provided within the interior of hydraulic cylinder140first and second guide rods152and154. The upper ends of guide rods152and154are secured to closure member144while the lower ends are received within recesses formed in adapter138. Piston142has passageways156and158therein that sealably receive guide rods152and154. In this way, piston142can be displaced by fluid pressure to move axially within cylinder140while guide rods152and154prevent the piston from rotating relative to the cylinder.FIG. 9shows the relationship between guide rods152and154and piston142.

By reference toFIGS. 8A and 8Bthe method of operation of the system of this invention to provide high temperature closure of pipe10can be seen. By application of hydraulic pressure to cylinder140, piston142can be forced downwardly, moving piston rod146and thereby tubular piston rod extender150downwardly so that the attached pipe sealing assembly46is moved into the interior of the assembly surrounding pipe10. When the assembly reaches its lowest level as defined by stop post92further downward force on the assembly initiates the movement of seal cups66and68away from each other and towards the plugging tool closed condition as shown inFIGS. 6 and 7. This action is achieved by four separate but cooperative actions as previously mentioned. First, divider guides114act against runners116to spread the cups apart. Then, the bottom ends of wedge members48and50engage the top edges of the rearward surfaces of the seal cups to urge them apart. In addition, the action of cam surfaces formed in lower support54and top support62guide the displacement of the seal cups away from each other. Finally the wedge surfaces of wedge member48and50slide against the rearward surfaces of seal cups66and68forcing them into metal-to-metal sealing relationship with toroidal collars12and14as seen inFIG. 7.

The pipe sealing assembly46is left in the double block and bleed position as shown inFIG. 7as long as it is necessary to block fluid flow through pipe10. When the need for blockage of flow through the pipe has ended the pipe sealing assembly46can be withdrawn and valve124closed. After removing the pipe sealing member46, a completion plug (not shown) can be inserted through the valve and into passageway40within flange member36. By mechanisms controlled through valve124the completion plug can be actuated to permanently close opening40through flange36. Thereafter pressure is contained within the containment assembly that surrounds pipe10and valve124can be removed. A flange plate can be then secured to flange member36top surface45and thereafter flow through pipe10can continue indefinitely.