Block and bleed plugging tool employing seals on a pipeline exterior

The present invention is a method of plugging a pipeline having an exterior surface including the steps of affixing to the exterior of the pipeline first and second spaced apart collars, welding each collar to the pipeline so that an operating space is provided between the collars, positioning a seal with each collar, affixing a containment housing to the opposed collars providing a confined space around the pipeline and surrounding the operating space between the collars, the confined space being accessed by a passageway, cutting and removing a length of pipeline between the collars providing opposed pipeline exterior end surfaces, 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 pipeline, and applying force to move the seal cups away from each other, the circumferential lips of the seal cups engaging with the opposed seals to compress them into sealing engagement with the collars and with the pipeline exterior surfaces.

REFERENCE TO PENDING APPLICATIONS

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

FIELD OF THE INVENTION

The invention relates to apparatus systems and methods for plugging a pipeline having liquids or gases flowing therethrough utilizing seals on the exterior of the pipeline.

BACKGROUND OF THE INVENTION

This invention relates to systems and methods for plugging a pipeline under pressure. “Pipeline” as used hereinafter is inclusive of any tubular member made of metal for carrying fluid (liquids or gases). Whereas U.S. Pat. No. 7,270,139 is particularly useful for controlling flow of high temperature liquids or gases, the present invention can be used for either ambient or high temperature applications. The composition of the elastomeric seals determines the range of the applicable temperature. However, the ferrule design may be used at elevated as well as ambient temperatures.

Tools or machines for tapping or for closing fluid flow therethrough include the following:

Tapping machines, such as the kind described in the above-mentioned U.S. patents, are for tapping a hole in a pipeline while liquids or gases are flowing through them, that is, while the pipeline 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 pipeline or to enable fluid flow through the pipeline to be blocked. Other examples of prior art that describe and illustrate plugging the interior of a pipe include the following U.S. Pat. Nos.:

BRIEF SUMMARY OF THE INVENTION

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 toroid 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 secured to the exterior of the pipe. Each collar has a machined face which can be achieved by machining 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 circumferential 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.

The sealing face of each collar includes a circumferential recess, or circumferential slot, adjacent the interior circumferential surface of the pipe to which they are affixed.

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 shape of the containment fittings can vary. One type of containment housing, as illustrated herein, is in the form of a sphere with an open top, or the housing can be non-spherical by having a bottom usually in the form of a cup shaped member with a flange fitting at the upper end.

After the containment housing, which may include a bottom member and an upper flange, has 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.

Even though the preferred embodiment for installing the collars is described above, it is recognized that the collars may be pre-welded to the containment fittings prior to being welded to the pipe.

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 components have been affixed to the exterior of the pipe, a tapping machine attached and a section of the pipe is cut and removed, the next step is to seal the opposed ends of the pipe employing a plugging tool. The plugging tool is inserted as an assembly into the interior of the containment housing. The plugging tool carries with it 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 opposed circumferential elastomeric seals supported in the circumferential slot on each collar.

In one embodiment 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 elastomeric seals carried by each of the collars. The plugging tool assembly includes translation apparatus for moving the top and bottom supports away from each other to thereby urge the seal cups towards the toroidal elastomeric seals.

In one embodiment of the invention a pair of wedge members are forced against rearward surfaces of the seal cups to simultaneously force them into sealing contact with the elastomeric seals on the toroidal collars. In this manner a double block and bleed plugging tool is achieved. After both of 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 elastomeric seals on the toroidal collars.

In another embodiment, the seal cups are forced into contact with the circumferential elastomeric seals by means a hydraulic cylinder having pistons extending from opposed sides, each piston being laterally displaced by hydraulic fluid forced into the hydraulic cylinder.

In another embodiment, the seal cups are forced into contact with malleable metallic ferrules which are sealably crimped onto the exterior of the pipe.

Further objects and features of the present invention will be apparent to those skilled in the art upon reference to the accompanying drawings and upon reading the following description of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that this invention is not limited in its application to the details of construction and arrangement of 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 the purpose of description and not of limitation.

Elements shown by the drawings are identified by the following numbers:

Referring to the drawings and first toFIG. 1, a cross-sectional view of the portion of a length of a pipeline is shown after the pipeline has been cut in two and a portion thereof removed in the practice of the invention. A first portion of the length of the pipeline is identified by the numeral10and a second portion of the same pipeline shown in cross-section is identified with the numeral12. A portion of the pipeline extending from the illustrated portions10and12has been removed, discarded and is not illustrated. Prior to removal of the missing portion,FIG. 1shows that a first circumferential angular collar14and a spaced apart, second collar16have been affixed to the pipeline. Each of the collars in their assembled form are short length tubular members. While not shown inFIG. 1each of collars14and16is formed of two halves that are assembled on the pipeline. The assembled portions are welded to the pipeline by rearward circumferential welds18and20. The semi-cylindrical collar portions are then welded longitudinally to each other (not seen inFIG. 1) so that after the welds are completed, collars14and16are each an integral short length cylindrical member having a forward face. The forward face of collar14is identified by the numeral22and, in like manner, the forward face of collar16is identified by the numeral24. The forward face22of collar14is provided with a circumferential slot26and in like manner, forward face24of collar16has a circumferential slot28. The collars14and16have rearward faces30and32where welds18and20are performed.

To provide containment of any fluid, whether liquid or gas, within pipeline10,12a containment housing consisting of a lower portion38and a corresponding containment housing upper portion40is secured to collars14and16by welds42. The containment housing upper portion40has an opening therein to which is secured a flange44of the type to which various piping fittings or valves can be secured by bolts (not shown).

Positioned within passageway46within flange44is a pipe sealing assembly48that is illustrated and described in detail in U.S. Pat. No. 7,270,139 which is incorporated herein by reference. The invention herein is not concerned with details of the pipe sealing assembly48but instead the essence of this invention is a method of forming seal around the external circumferential surface pipeline10,12as a method of closing off fluid flow through the pipeline. Essentially the pipe sealing assembly48includes a top support50and a lower support52.

Positioned between top support50and lower support52, that are retained by vertical shaft54, is a first seal cup56and, opposed to it, a second seal cup58.

As seen inFIG. 2, first seal cup56has upwardly extending arms60that are supported to a first roller62. Seal cup58has upwardly extending arms64that are supported to a second roller66. As seen inFIG. 1, first seal cup56has downwardly extending arms68while second seal cup58has downwardly extending arms70. These downwardly extending arms68and70are supported to lower rollers72and74. As seen inFIG. 2, lower support52has a pair of cam slots75and76that receives lower rollers72and74. In like manner, top support50has a pair of cam slots78and80that receives upper rollers62and66. When top support50is moved in a direction away from lower support52, rollers62,66,72and74acting in the cam slots75,76,78and80serve to deflect seal cups56and58toward each other and when top and bottom supports50and52move towards each other, seal cups56and58are forced away from each other.

Received on shaft54and compressibly positioned between lower support52and top support50is a compression spring82. The downward translation of shaft guide84and top plate86and with it first and second wedge members88and90, forces top support50towards lower support52compressing spring82and moving the top roller62and66within the cam formed in top support50and bottom rollers72and74within the cam formed in lower support52. This cam action causes first and second seal cups56and58to displace outwardly with respect to each other. The downward movement of lower support52is limited by a stop post92affixed to the interior of containment housing lower portion38.

First seal cup56has on its forward face a circumferential recess94. In like manner, second seal cup58has in its forward face a circumferential recess96. The function of recesses94and96are to receive the outer ends of pipe portions10and12respectively as seal cups56and58are expanded outwardly with respect to each other. This allows a circumferential sealing surface102on first seal cup56and a corresponding circumferential sealing surface104on sealing cup58to simultaneously engage circumferential elastomeric seals34and36.

When seal cups56and58are displaced away from each other circumferential sealing surface102of first seal cup56and circumferential sealing surface104of second seal cup58simultaneously engage circumferential elastomeric seals34,36. This engagement closes communication between the interior of pipeline portions10and12thereby blocking fluid flow through the pipeline. When circumferential sealing surfaces102and104engage circumferential elastomeric seals34and36they simultaneously compress the elastomeric seals to increase sealing pressure against the external circumferential surface of pipe portions10and12. When the pipe sealing assembly48as shown inFIGS. 1,2and3is upwardly withdrawn, the seal cups56and58are removed to leave fluid flow through pipe portions10and12unobstructed.

FIG. 3shows an alternate arrangement for the invention wherein, rather in a spherical containment housing as shown inFIGS. 1 and 2, containment is achieved by the use of a lower containment portion106and an upper containment portion108. While not illustrated in the drawings these containment housing portions are each formed by two halves that are welded together and simultaneously welded to collars110and112. While the cross-sectional configuration of collars110and112are completely different than collars14and16as seen inFIGS. 1 and 2, the basic functions are the same.FIG. 3collars110and112are each trapezoidal and have frusto-conical surfaces114facing in the direction towards seal cups56and58.

A further difference betweenFIG. 3and the embodiment ofFIGS. 1 and 2is that inFIG. 3the circumferential elastomeric seals116and118are trapezoidal to form a mating relationship with collars110and112. In the arrangement ofFIG. 3as the seal cups56and58advance away from each other their circumferential sealing surfaces102and104compress circumferential seals116and118into sealing contact with collars110and112and, in addition, because of the angular relationship between the circumferential seals and the collars, the elastomeric seals are radially inwardly depressed relative to pipe portions10and12to effect increase sealing with the exterior of the pipe portions10and12.

FIG. 4shows an alternate embodiment of the invention which functions in the same way as the embodiments shown inFIGS. 1 through 3except that a different system is employed to force seal cups56and58away from each other and into sealing engagement with circumferential elastomeric seals34and36held in position by collars14and16. Whereas the embodiments ofFIGS. 1,2and3utilize mechanical forces to urge seal cups56and58in directions towards collars14and16, in the embodiment ofFIG. 4hydraulic force is employed.FIG. 4shows a tubular housing120extending upwardly from flange44. Positioned between seal cups56and58is a double ended hydraulic cylinder122. Extending downwardly from the exterior of cylinder122, a positioning element124that has a recess126in the lower end thereof, the recess receiving the upper end of stop post92. The function of the cooperative relationship between stop post92and positioning member124is to accurately locate double ended hydraulic cylinder122in alignment with pipe ends10and12.

Extending from opposed ends of double ended cylinder122are pistons128and130. From a source of hydraulic fluid pressure132(not shown), a flexible hose134conveys fluid pressure to an inlet136of double ended hydraulic cylinder122so that when hydraulic force is applied by fluid through hydraulic hose134cylinders128and130are simultaneously forced outwardly in opposed directions to apply force against first and second seal cups56and58. Thus the double ended hydraulic cylinder122with opposed pistons128and130provide the same action as is provided by pipe sealing assembly48inFIGS. 1,2and3.

Each ofFIGS. 5 through 8functions in essentially the same way as the embodiments ofFIGS. 1 through 4except that in each ofFIGS. 5,6,7and8modifications are made in the interrelationship between the collars, the forward end the seal cups and the arrangement of the circumferential seals.

InFIG. 5the circumferential collar138surrounding pipe portion10and to which upper and lower portions of containment housing38and40are welded is square in cross-sectional configuration. Collar138has a forward face141that extends radially of the axis of pipe section10. InFIG. 5seal cup56A has a forward face140with an internal circumferential slot142having a circumferential inclined surface144that engages a circumferential elastomeric seal146. The arrangement of internal circumferential slot142serves to capture elastomeric seal146and to compress it into sealed engagement between the forward face141of collar138and the exterior surface of the pipe10. Further the arrangement ofFIG. 5is different from that inFIGS. 1,2and3in that the circumferential elastomeric seal146has cloth148on its forward surface where contact is made with collar138. A further difference is that in the embodiment ofFIG. 5a snap ring150is positioned in circumferential slot142to provide backup for circumferential elastomeric seal146. The arrangement ofFIG. 5provides compressive containment of circumferential elastomeric seal146as seal cup56A applies compressive force to form a seal engagement between seal cup56A and the exterior surface of pipe10.

FIG. 6shows an embodiment wherein the collar138A has a forward face with a circumferential notch142A as shown in the forward face of collar14ofFIGS. 2 and 4. However,FIG. 6shows the arrangement wherein the circumferential elastomeric seal36A has a forward cloth face148as shown inFIG. 5plus a rearward cloth face152. The double cloth faces148and152ofFIG. 6provides a circumferential elastomeric seal36A having a greatly improved dimensional stability.

FIGS. 7 and 8show additional alternate embodiments of the manner in which elastomeric seals can be employed in a plugging tool that seals against the exterior surface of a pipe. InFIG. 7collar138A is the same as collar138A ofFIG. 6and has an internal circumferential slot that receives a circumferential elastomeric seal146A that has, confined within the elastomeric seal an anti-extrusion spring154. This coiled anti-extrusion spring154reinforces the internal circumferential edge of the elastomeric seal to reduce the extrusion of the seal into the space between the exterior of pipe10and the interior surface156of the circumferential slot provided in seal cup56B.

FIG. 8has the improvements and advantageous ofFIG. 7plus the provision of a forward cloth face158affixed to circumferential seal146A. In addition,FIG. 8employs the advantageous of an anti-extrusion spring154as has been described with reference toFIG. 7.FIG. 8shows the advantageous of the combination of an anti-extrusion spring and a cloth surface to reinforce circumferential elastomeric seal146A.

As previously stated the invention herein is similar in many respects to the cam-assisted, wedge actuated, metal-to-metal seal, block and bleed plug tool of U.S. Pat. No. 7,270,138 with an important distinction and that is the patent teaches a block and bleed tool in which sealing is achieved by contact of metal sealing cups with metal collars, that is, metal-to-metal sealing. Whereas the present invention provides for the use of both elastomeric and metal seals and particularly provides for the unique concept of applying these seals to the exterior surface of pipe to secure a leak-proof block and bleed plugging tool. Applying seals to the exterior surface of a pipe have an important advantage compared to applying seals directly to ends of pipe or to the internal surface of pipe. This improvement is achieved since the outside surface of the pipe can be thoroughly cleaned of rust, debris, irregularities and so forth to thereby greatly improve the effectiveness of an apparatus to form leak-proof closure of the pipe. The invention herein provides improved and unique ways of using an elastomeric or a metal seal against the pipe exterior surface that achieves more consistent and superior results to other types of double block and bleed sealing systems.

WhileFIGS. 1 through 8illustrate apparatuses, systems and methods of providing block and bleed of a pipeline by using elastomeric seals on the exterior of the pipeline,FIGS. 9 through 16show such tools, apparatuses, systems and methods for sealing exposed ends of a pipeline by employing metal ferrules secured to the pipeline exterior.

As shown inFIG. 9, a metallic ferrule160is removably supported to the forward face of first seal cup56. To removably retain ferrule160on the forward surface of seal cup56, a plurality of radially spaced apart retainers162are employed. Each retainer is an elongated metallic clip that is secured to the external circumferential surface of first seal cup56and held in place by a threaded bolt164. Each of the retainers162has a recess166adjacent its forward end. Retainers162are flexible so that metallic ferrules160are held in position so that they can be advanced over the end of a cut length of pipeline but after the fenules are secured in position on the exterior surface of the pipeline, the seal cup56can be withdrawn, leaving the ferrules160in position on the pipeline.

FIG. 10shows the first and second seal cups56and58deployed to seal against the portions of the pipeline10and12. The ferrules160are crimped to the frusto-conical forward faces168of the first and second collar14and16and the exterior surface of the pipeline.

FIG. 11shows a seal cup56in position to insert a ferrule160onto the end of the pipeline whileFIG. 12shows the relationship of the seal cup56after the ferrule160has been positioned on the exterior surface of the pipeline and in contact with the forward face168of first collar14.FIG. 12shows the ferrule160in position on the outer exterior end10of a pipeline which has been cut into and with the ferrule160in position to be crimped.

FIG. 13shows force being applied against seal cups56to crimp the malleable metallic ferrule160so that it is permanently deformed to engage the exterior surface of pipe10and simultaneously to sealably engage the forward face168of collar14.

Ferrule160is metallic and is preferably of a malleable material that can, with sufficient force and pressure, be deformed to sealably contact the exterior surface of pipe10and simultaneously the forward surface168of collar14.

FIG. 14shows the ferrule160as having been permanently deformed into sealing engagement with the exterior surface of pipe10and forward face168of collar14.

FIG. 15illustrates how the retainers162release the ferrule160as the seal cup56is retracted from the portion of the pipeline10. The ferrule160remains crimped to the exterior surface of the portion of pipeline10and the forward face168of the collar14.

FIG. 16shows a slightly alternate embodiment involving collar14in which, rather than having a frusto-conical forward face168as inFIGS. 10 through 15has a planar radial face170. The embodiment ofFIG. 16illustrates that the face configuration for collar14can vary as required to ensure effective distortion of ferrule160by the application of pressure against seal cup56.

FIG. 16shows an additional alternate embodiment in the configuration of retainer162. InFIG. 16the retainer162is thinner in the rearward direction while nevertheless providing a retention recess166so that ferrule160is retained in position as it is carried forward in the initial stages of the process of inserting the ferrule forward onto the end of a pipe as illustrated. The retainers162are essentially configured like a leaf-spring so they can flex within their elastic limit to retain a ferule in position to position it onto the end of a pipeline and hold it in such position as pressure is applied to deform the ferrule into permanent sealing engagement with the exterior of the pipeline and with a forward face of the collar which it contacts but nevertheless the spring tension is such that as the seal cup56is withdrawn as shown inFIGS. 14 and 15, the springs easily deflect to leave the deformed ferrule circumferentially surrounding the pipe10and in sealed engagement with the forward face of collar14.

The invention herein has been illustrated to show how external seals can be employed to provide block and bleed functions to a pipeline that has been cut to allow fluid flow through the pipeline to be blocked wherein sealing is achieved by elastomeric members that require less forceful pressure to achieve sealing or by metallic members, such as the metallic ferrule illustrated and described herein wherein greater application pressure is required but thereby providing a closing system that is effective to maintain pipe closure even in the presence of high temperature, such as a fire. Further the use of a metal ferrule sealing system achieves longer life expectancy of the closure system since, unlike some elastomerics the ferrules used in practicing this invention may be of metals and alloys that can withstand the application to which they are put for extended periods of time. A period of time may be the life expectancy of the pipeline on which the invention herein is utilized.