Isolation tool and method for isolating a pipe

Abstract

An isolation tool 10 for deployment into the section of pipe (P) via a single, lateral, pipe opening (O) in a wall (W) of the pipe, comprising a seal unit 12. The seal unit comprises first and second

Description

FIELD This relates to an isolation tool and method for isolating a pipe. In particular, but not exclusively, this relates to an isolation tool and method for isolating a pipe in the form of a pipeline utilised to transport hydrocarbons, carbon dioxide, hydrogen or the like. BACKGROUND Transporting substances, in particular fluids, over distance is required in many industries, this typically being achieved via a system of pipes, tubes, pipe modules, pipelines and the like. In the energy industry, for example, pipelines are used in surface, subsurface and / or subsea environments to transport oil and / or gas, often over large distances. In some instances, it may be necessary or desirable to gain access to a “live” section of pipe, that is, containing fluid at pressure, in order to isolate a section of the pipe for repair, replacement or to permit deployment of tooling into the pipe. However, isolation of a “live” section of pipeline containing substances, e.g. fluids, at pressure is technically challenging. One technique used for gaining access to a live section of pipe is known as hot tapping. Hot tapping involves the fitting of a branch connection, typically a split tee connection, around the section of the pipe in which the opening is to be formed. The branch connection may be welded or mechanically secured to the pipe. A valve, e.g. a slab valve, is then fitted to the branch connection. The valve is reconfigurable between a closed configuration in which a throughbore of the valve is closed and an open configuration in which the throughbore is open. When it is desired to form the opening in the wall of the pipe, the valve is configured in, or reconfigured to, its open configuration so as to permit a drilling tool, known as a hot tapping tool, to be deployed through the valve, the branch connection and the wall of the pipe so as to form the opening in the wall of the pipe. Once the opening has been formed, the drilling tool is removed and the valve arrangement reconfigured to its closed configuration, the valve subsequently controlling access to the pipe via the opening. Beneficially, hot tapping facilitates the creation of the opening in the wall of the pipe while maintaining pressure integrity. While hot-tapping-based isolation tools and techniques have been used extensively, the ability to perform an effective pressure test is limited. For example, although two seals are present, only the primary seal is in fact effective against the isolated pressure. In addition, each intervention into the pipe requires additional planning, setup and operation time resulting in increased costs for the operator. Applicant’s GB 2,440,275 B and GB 2,474,883 B provide alternative solutions, whereby a device comprising a rotatable seal unit in the form of a spherical or globe seal module may be installed through a branch connection. The seal module carries a pair of seal elements and the module is configured such that the pressure differential acting across the module further energises the seal elements. Thus, in the event of a failure of the external seal activation, isolation is maintained. Furthermore, an annular chamber between the seal elements may be pressurised to confirm the integrity of both seal elements. The arrangement of the seal module also permits the device to be utilised as a weld test tool, e.g. by locating the device so that the seal elements straddle a weld, and then pressurising the annulus between the seal elements. SUMMARY Aspects of the present disclosure relate to an isolation tool and method for isolating a pipe. In particular, but not exclusively, aspects of the disclosure relate to an isolation tool and method for isolating a pipe in the form of a pipeline utilised to transport hydrocarbons, carbon dioxide, hydrogen or the like. According to a first aspect, there is provided an isolation tool for use in isolating a section of a pipe, the isolation tool comprising: a seal unit configured for location in the section of pipe to be isolated, the seal unit comprising: a seal arrangement comprising at least a first seal element and a second seal element, the first and second seal elements configured and / or operable to engage a wall of the pipe; and a seal actuation arrangement configured and / or operable to urge the first and second seal elements into sealing engagement with the wall of the pipe, wherein the seal actuation arrangement comprises a first piston and a second piston, wherein the first piston is configured and / or operable to move in a first direction so as to actuate both the first and second seal elements, and wherein the second piston is configured and / or operable to move in a second, opposite, direction so as to actuate both the first and second seal elements. In use, the seal unit may be configured and / or operable for location in the section of pipe via a single opening in the wall of the pipe. More particularly, and as will be described further below, the isolation tool may comprise or may be coupled to a launcher arrangement configured and / or operable to deploy the seal unit into the pipe. The isolation tool may be configured and / or operable so that the seal unit is pivotable relative to the launcher arrangement such that the seal unit can be located in either an upstream or downstream location relative to the opening in the pipe. Beneficially, the isolation tool is configured and / or operable to provide a dual seal isolation of a section of pipe and pressure testing capability via a single intervention into the pipe, obviating the operation time and / or cost associated with conventional hot tapping techniques and equipment Alternatively or additionally, as the seal unit may be deployed into a fluid flow within the pipe while in an unset configuration, offering significant bypass, the isolation tool can be deployed safely in pipes having high flow rates. This beneficially facilitates the setting of the seal arrangement in a controlled fashion. Moreover, the present isolation tool is capable of being installed either toward the pressure (upstream deployment) or away from the pressure (downstream deployment) via the same opening in the pipe, facilitating isolation and pressure testing in either direction at any given time; and without the requirement to remove and reinstall the isolation tool or physically reconfigure the isolation tool for upstream or downstream operation. The present isolation tool is also capable of testing to above fully rated line pressure, so that new piping installations may be pressure tested to higher limits before being placed in operation. The isolation tool may comprise a body. The body may form part of the seal unit. In particular embodiments, the body may define a mandrel or core of the seal unit. The body may be configured and / or operable to carry components of the seal unit, e.g. the seal arrangement and the seal actuation arrangement. As described above, the isolation tool comprises a seal arrangement comprising at least a first seal element and a second seal element. The first seal element may be disposed on and / or carried by the body. The first seal element may be annular. The first seal element may comprise or take the form of an elastomeric seal element. The first seal element may comprise or take the form of a compression seal element, i.e. the first seal element may be configured and / or operable to expand radially outwards when subject to axial compression. Beneficially, the provision of a compression seal means that the first seal element is highly compliant to the pipe, facilitating leak tight sealing in poor pipe bore conditions. The first seal element may provide a bi-directional seal with the wall of the pipe, i.e. the first seal element may provide a seal capable of withstanding a pressure differential acting in either the first direction or the second direction. In some embodiments, the first seal element may comprise an anti-extrusion spring. The second seal element may be axially spaced from the first seal element. The second seal element may be disposed on and / or carried by the body. The second seal element may be annular. The second seal element may comprise or take the form of an elastomeric seal element. The second seal element may comprise or take the form of a compression seal element, i.e. the second seal element may be configured and / or operable to expand radially outwards when subject to axial compression. Beneficially, the provision of a compression seal means that the second seal element is highly compliant to the pipe, facilitating leak tight sealing in poor pipe bore conditions. The second seal element may provide a bi-directional seal with the wall of the pipe, i.e. the second seal element may provide a seal capable of withstanding a pressure differential acting in either the first or second direction. In some embodiments, the first seal element may comprise an anti-extrusion spring. At least one of the first seal element and the second seal element may be configured to be self-energising, e.g. on the seal unit experiencing a pressure differential exceeding a selected threshold. Beneficially, either or both of the first and second seal elements may be maintained in an energised state by dual actuation means during the isolation. In applications where the seal unit experiences a pressure differential exceeding the selected threshold. The first seal element may be defined as an outboard seal element, since in use it will be disposed closer distal to the launcher arrangement and pipe opening. The second seal element may be defined as an inboard seal element, since in use it will be disposed proximal to the launcher arrangement and pipe opening. The isolation tool may comprise a seal support member. The first and second seal elements are disposed on and / or carried by the seal support member. The seal support member may be configured and / or operable to support the first and second seal elements. The seal support member may form part of the seal unit. The seal support member may comprise a base portion. The first and second seal elements may be disposed on the base portion. The base portion may carry the first and second seal elements. The base portion may be annular. The seal support member may comprise a radially extending flange portion. The flange portion may extend radially outwardly from the base portion. The flange portion may be disposed between the first and second seal elements. The flange portion may be annular. The flange portion may take the form of an annular ring. In particular embodiments, the flange portion may be tapered, being thinner at its radially outmost surface than its base. In particular embodiments, the base portion and the flange portion are integrally formed. Alternatively, the flange portion may alternatively comprise separate components coupled together to form the seal support member. The seal support member may be supported by and / or carried by the first and second pistons. As described above, the isolation tool comprises a seal actuation arrangement configured and / or operable to urge the first and second seal elements into sealing engagement with the wall of the pipe, the seal actuation arrangement comprising a first piston configured and / or operable to move in a first direction and a second piston configured and / or operable to move in a second, opposing, direction to said first direction. The seal actuation arrangement may comprise or take the form of a fluid-powered actuation arrangement. In particular, the seal actuation arrangement may comprise or take the form of a hydraulic actuation arrangement. However, it will be understood that the seal actuation arrangement may take other forms such as a pneumatic actuation arrangement. The first piston may be operatively associated with the first seal element. The first piston may be defined as an outboard piston. The first piston may be disposed on and / or carried by the body. The first piston may be configured and / or operable to move in said first direction so as to urge the first and second seal elements into sealing engagement, or further sealing engagement, with the wall of the pipe, said first direction being towards the first and second seal elements. A first piston chamber may be provided. The first piston chamber may be between e.g. formed between, the first piston and the body. The first piston chamber may be configured to receive an actuation fluid, e.g. hydraulic fluid, so as to urge the first piston in said first direction. A first piston cap may be provided. The first piston cap may be configured and / or operable to form an end of the first piston chamber, the first piston forming the other end of the first piston chamber. The first piston cap may be configured and / or operable to prevent leakage of the actuation fluid from the first piston chamber. The first piston cap may comprise one or more seal elements, in particular embodiments at least a primary seal element and a secondary seal element. In particular embodiments, the first piston cap comprises one or more grooves for receiving the one or more seal elements therein. A retention nut may be provided. The retention nut may be configured and / or operable to retain the first piston cap. The retention nut may be disposed on the body. The retention nut may be disposed outboard of the first piston cap. The isolation tool may comprise a first pressure head. The first pressure head may be defined as an outboard pressure head. The first pressure head may be coupled to, e.g. mounted on, or may form part of, e.g. may be integrally formed with, the first piston. In use, movement of the first piston in said first direction moves the first pressure head in said first direction. The first pressure head may be operatively associated with the first seal element. The first pressure head may be configured and / or operable to engage the first seal element. The second piston may be operatively associated with the second seal element. The second piston may be defined as an inboard piston. The second piston may be disposed on and / or carried by the body. The second pressure head may be coupled to or form part of the second piston. The second piston may be actuable independently of the first piston. The second piston may be configured and / or operable to move in said second direction so as to urge the first and second seal elements into sealing engagement, or further sealing engagement, with the wall of the pipe, said second direction being towards the first and second seal elements. A second piston chamber may be provided. The second piston chamber may be between e.g. formed between, the second piston and the body. The second piston chamber may be configured to receive an actuation fluid, e.g. hydraulic fluid, so as to urge the second piston in said second direction. The second piston may form a first end of the second chamber, the body forming the other end of the second piston chamber. The isolation tool may comprise a second pressure head. The second pressure head may be defined as an inboard pressure head. The second pressure head may be coupled to, e.g. mounted on, or may form part of, e.g. may be integrally formed with the second piston. In use, movement of the second piston in said second direction moves the second pressure head in said second direction. The second pressure head may be operatively associated with the second seal element. The second pressure head may be configured and / or operable to engage the second seal element. It will be understood that the isolation tool may be operable in two different modes in order to actuate the seal arrangement. In a first mode, which may be defined as an upstream mode, the first piston is actuated to move in said first direction to cause actuation of both the first and second seal elements. More particularly, in this first mode, movement of the first piston in said first direction moves the first pressure head in said first direction. This in turn may cause the first seal element, the seal support member and the second seal element to move in said first direction, such that the first and second seal elements are axially compressed between the first pressure head and the second pressure head. This in turn may cause the first and second seal elements to radially expand into engagement or further engagement with the wall of the pipe. In a second mode, which may be defined as a downstream mode, the second piston is actuated to move in said second direction to cause actuation of both the first and second seal elements. More particularly, in this second mode, movement of the second piston in said second direction moves the second seal element, the seal support member and the first seal element in said second direction, such that the first and second seal elements are axially compressed between the first pressure head and the second pressure head. This in turn may cause the first and second seal elements to radially expand into engagement or further engagement with the wall of the pipe. Thus, the configuration of the isolation tool, which facilitates operation in either said first mode or second mode as required, permits the isolation of either an upstream or downstream section of the pipe to be achieved without the requirement to locate the seal unit in a particular orientation, or to remove and redress the isolation tool. Moreover, the configuration of the isolation tool permits self-energisation of the first and second seal elements in both modes. The isolation tool may comprise a fluid communication arrangement for controlling the supply and / or venting of the fluid, e.g. actuation fluid, from the first and / or second piston chambers. The fluid communication arrangement may comprise one or more fluid communication passages in, e.g. formed in, the body. The fluid communication arrangement may comprise or define “set” porting and separate “unset” porting. Alternatively, a single communication passage may be utilised to both supply and vent from the first piston chamber and a single communication passage may be utilised to both supply and vent from the second piston chamber. The isolation tool may comprise a swivel. The swivel may be configured and / or operable to permit fluid communication to the seal unit while at the same time permitting the seal unit to pivot relative to the launcher arrangement. The swivel may comprise a core and a rotatable ring. The rotatable ring is rotatable relative to the core. The swivel may be disposed at or adjacent to the clevis pin. The swivel comprises a fluid communication arrangement configured and / or operable to maintain fluid communication when the seal unit pivots. A seal arrangement is provided to maintain sealing integrity between the core and the rotatable ring when the seal unit pivots. In particular embodiments, the seal arrangement comprises low RPM, high pressure rotational seals. Beneficially, the seals permit the swivel to turn with minimul friction and no or negligible pressure loss. Moreover, fluid lines, e.g. hydraulic lines, for communicating between the seal unit and the operator controls may be routed through the swivel, providing reliable and effective communication regardless of the high angular variation seen when pivoting between the in-line orientation and the perpendicular or substantially perpendicular orientation, and vice-versa. Alternatively or additionally, the fluid lines are not subjected to bending which may otherwise reduce their reliability and / or facilitates the use of larger bore fluid lines, enabling better hydraulic communication with thick liquid isolation commodities. The isolation tool may comprise a release arrangement. The release arrangement may be configured and / or operable to reconfigure the seal unit so that the seal with the wall of the pipe is released. In particular embodiments, the release arrangement may be configured and / or operable to urge the first piston in the second direction and / or urge the second piston member in the first direction. The release arrangement may comprise an actuator arrangement (“release actuator arrangement”). The release actuator arrangement may comprise one or more actuators, e.g. linear actuators. In particular embodiments, one or more of the actuators may comprise or take the form of a fluid-powered actuator, e.g. a hydraulic piston or a pneumatic piston. Alternatively, one or more of the actuators may comprise or take the form of an electric actuator. Alternatively or additionally, the release arrangement may comprise pressurising a space, e.g. head cavity, between the first and second pistons. Beneficially, the release arrangement pushes the first and second pistons apart, thereby facilitating unsetting the tool regardless of which of the first and second pistons is activated. Alternatively or additionally, the tool may be configured and / or operable to passively unset. For example, if the seal actuation arrangement is vented (e.g. a hydraulic set circuit coupled to or operatively with the seal actuation arrangement is vented) and fluid pressure between the first and second seal members is equalised or substantially equalised (e.g. via the fluid communication arrangement), the tool may unset passively. The isolation tool may comprise a fluid communication arrangement. The fluid communication arrangement may be configured and / or operable to communicate a fluid, e.g. a test fluid, to an annulus defined between the first and second seal elements when the first and second seal elements are engaged with the pipe. The annulus may be defined as a test annulus, since it may facilitate integrity testing of either or both of the first and second seal elements and / or may facilitate testing of a pipe connection, e.g. weld. The fluid communication arrangement may comprise a fluid communication passage in, e.g. formed in, the seal support member, more particularly the flange portion. The fluid communication passage may be configured and / or operable to communicate the fluid, e.g. the test fluid, to the annulus. The fluid communication arrangement may comprise a fluid conduit configured and / or operable to communicate the fluid, e.g. test fluid, from a fluid source to the fluid communication passage in the seal support member. The fluid conduit may be formed in the isolation tool or may alternatively or additionally comprise a fluid line such as a hydraulic line or the like. Beneficially, the fluid communication arrangement permits both either or both of the first and second seal elements to be independantly tested to the pipeline pressure. Alternatively or additionally, as this is a permanent connection during the isolation, the annulus could be used to provide a bleed between the first and second seal elements where leak tight sealing of the first seal element proves impractical. As described above, the isolation tool may comprise or may be configured for coupling to a launcher arrangement. The launcher arrangement may be configured and / or operable to deploy the seal unit into the pipe. The isolation tool may be configured and / or operable so that the seal unit is pivotable relative to the launcher arrangement such that the seal unit can be located in either an upstream or downstream location relative to the opening in the pipe. In use, the seal unit may be pivotable from a first, in-line, orientation relative to the launcher arrangement to a perpendicular or substantially perpendicular orientation relative to the launcher arrangement. The seal unit may for example be defined as bi-directional, i.e. the seal unit may be pivotable in either or both upstream and / or downstream directions. The launcher arrangement may comprise a clevis, for example comprising clevis plates and a clevis pin. The launcher arrangement may further comprise one or more bearing pads or the like. Beneficially, the fluid pressure force acting on the seal unit may be safely transferred to the pipe via the body and launcher arrangement. The body may comprise or define a padeye. The padeye may be configured for mounting on the clevis. The isolation tool may further comprise an actuator arrangement. The actuator arrangement may be configured and / or operable to pivot the body relative to the launcher arrangement. The actuator arrangement may comprise one or more actuators, in particular but not exclusively linear actuators. One or more of the actuator may comprise or take the form of a fluid-powered actuator, e.g. a hydraulic actuator or a pneumatic actuator. One or more of the actuator may comprise or take the form of an electric actuator. According to a second aspect, there is provide a method for isolating a section of a pipe, using the isolation tool of the first aspect. It will be recognised that the isolation tool and method of the present disclosure provide a number of significant benefits, including amongst other things the ability to provide fail safe, self-energised seals as well as 100% contingency in the load path in either upstream or downstream orientations without having to disassemble and reassemble the core components to provide an isolation which can be assessed to be the equivalent of double block and bleed isolation required by industry. Alternatively or additionally, the dual direction sealing capability of the isolation tool and method mean that the isolation tool can be used as a pressure test boundary for pipework reinstatement testing at higher pressures than previously designed and in either direction. Alternatively or additionally, since the seal unit can be rotated downstream (toward the isolated section), the isolation tool and method facilities the ability to tie-in a bypass through the same pipe opening as that through which the isolation tool is deployed. The invention is defined by the appended claims. However, for the purposes of the present disclosure it will be understood that any of the features defined above or described below may be utilised in isolation or in combination. For example, features described above in relation to one of the above aspects or below in relation to the detailed description below may be utilised in any other aspect, or together form a new aspect. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the present invention will now be described, byway of example only, with reference to the accompanying drawings, in which: Figure 1 shows a diagrammatic view of an isolation tool for isolating a section of a pipe; Figure 2 shows an enlarged view of a seal unit of the isolation tool shown in Figure 1; Figure 2A shows an enlarged view of part of the seal unit shown in Figure 2; Figures 3 &4 show a perspective swivel of the isolation tool shown in Figure 1; Figure 5 shows a diagrammatic view of the isolation tool shown in Figure 1, in a first mode of operation; and Figure 5A shows an enlarged view of the seal unit shown in Figure 5; Figure 6 shows a diagrammatic view of the isolation tool shown in Figure 2, in a second mode of operation; and Figure 6A shows an enlarged view of the seal unit shown in Figure 6. DETAILED DESCRIPTION OF THE DRAWINGS Referring first to Figures 1 and 2 of the accompanying drawings, there is shown an isolation tool 10 for use in isolating a section of a pipe P. As shown in Figure 1, and as will be described further below, the isolation tool 10 is configured for deployment into the section of pipe P via a single, lateral, pipe opening O in a wall W of the pipe P, thereby obviating the operation time and / or cost associated with conventional techniques and equipment which require either multiple pipe openings and seal deployments and / or which require deployment of tooling from an end or ends of the pipe P. Moreover, the isolation tool 10 is capable of being installed either toward the pressure (upstream deployment) or away from the pressure (downstream deployment) via the same opening in the pipe P, facilitating isolation and pressure testing in either direction at any given time; and without the requirement to remove and re-install the isolation tool 10 or physically redress the isolation tool 10 for upstream or downstream operation. In the arrangement shown in Figure 1, the opening O is formed by a hot tapping process. A branch connection T, which as shown in Figure 1 takes the form of a split tee connection, is located around the section of the pipe P in which the opening O is to be formed. The branch connection T is welded or mechanically secured to the pipe P. A valve V, which as shown in Figure 1 takes the form of a hot tap valve (e.g. comprising a slab valve, a ball valve, or other full bore conduit valve), is then fitted to the branch connection T. The valve V is reconfigurable between a closed configuration in which a throughbore THR of the valve V is closed and an open configuration in which the throughbore THR is open. When it is desired to form the opening O in the wall W of the pipe P, the valve V is configured in, or reconfigured to, its open configuration so as to permit a drilling tool (not shown), known as a hot tapping tool, to be deployed through the valve V, the branch connection T and the wall W of the pipe P so as to form the opening O. Once the opening O has been formed, the drilling tool is removed and the valve V reconfigured to its closed configuration, the valve V subsequently controlling access to the pipe P via the opening O. Beneficially, hot tapping facilitates the creation of the opening O in the wall W of the pipe P while maintaining pressure integrity. Referring in particular to Figure 2, the isolation tool 10 comprises a seal unit, generally denoted 12, which in the illustrated isolation tool 10 comprises or takes the form of a generally spherical seal module. The seal unit 12 comprises a seal arrangement, generally denoted 14, comprising at least a first seal element 16 and a second seal element 18. The first and second seal elements 16, 18 are configured and / or operable to engage the wall W of the pipe P (as shown in Figures 5 and 6 and described below). The isolation tool 10 further comprises a seal actuation arrangement, generally denoted 20, the seal actuation arrangement 20 configured and / or operable to urge the first and second seal elements 16, 18 into sealing engagement with the wall W of the pipe P. The seal actuation arrangement 20 comprises a first piston 22 and a second piston 24. When actuated, the first piston 22 is configured and / or operable to move in a first direction A so as to actuate both the first and second seal elements 16, 18 whereas the second piston 24, when actuated, is configured and / or operable to move in a second, opposite, direction B so as to actuate both the first and second seal elements 16, 18. As shown most clearly in Figure 2, a cavity 26 is formed within the seal unit 12 between the first piston 22 and the second piston 24, permitting movement of the first and / or second pistons 22, 24 relative to the body 28. As will be described further below, in use the cavity 26 may also be vented to facilitate seal self-energisation. In use, the seal unit 12 is configured and / or operable for location in the section of pipe P via the single opening O in the wall W of the pipe P. More particularly, and as will be described further below, the isolation tool 10 comprises or is coupled to a launcher arrangement (66 described below) configured and / or operable to deploy the seal unit 12 into the pipe P. The isolation tool 10 is configured and / or operable so that the seal unit 12 is pivotable relative to the launcher arrangement 66 such that the seal unit 12 can be located in either an upstream or downstream location relative to the opening O in the pipe P. Beneficially, the isolation tool 10 is configured and / or operable to provide a dual seal isolation of a section of pipe P and pressure testing capability via a single intervention into the pipe P, obviating the operation time and / or cost associated with conventional hot tapping techniques and equipment. Moreover, the isolation tool 10 is capable of being installed either toward the pressure (upstream deployment) or away from the pressure (downstream deployment) via the same opening in the pipe P, facilitating isolation and pressure testing in either direction at any given time; and without the requirement to remove and re-install the isolation tool 10 or physically reconfigure the isolation tool 10 for upstream or downstream operation. The isolation tool 10 is also capable of testing to above fully rated line pressure, so that new piping installations may be pressure tested to higher limits before being placed in operation. As shown in Figure 2, the isolation tool 10 comprises a body 28. In the illustrated isolation tool 10, the body 28 defines a mandrel or core of the seal unit 12 and is configured and / or operable to carry components of the seal unit 12, e.g. the seal arrangement 14 and the seal actuation arrangement 20. The seal arrangement 12 comprises the first seal element 16 and the second seal element 18. In the illustrated isolation tool 10, the first seal element 16 takes the form of an annular elastomeric compression seal element, the first seal element 16 being configured and / or operable to expand radially outwards when subject to axial compression. In use, the first seal element 16 provides a bi-directional seal with the wall W of the pipe P, i.e. the first seal element 16 provides a seal capable of withstanding a pressure differential acting in either the first direction A or the second direction B. The second seal element 18 is axially spaced from the first seal element 16. The second seal element 18 takes the form of an annular elastomeric compression seal element, the second seal element 18 configured and / or operable to expand radially outwards when subject to axial compression. In use, the second seal element 18 provides a bi-directional seal with the wall W of the pipe P, i.e. the second seal element 18 provides a seal capable of withstanding a pressure differential acting in either the first direction A or the second direction B. As shown in Figure 2A, in the illustrated isolation tool 10 the first seal element comprises an anti-extrusion spring 30 and the second seal element 18 comprises an anti-extrusion spring 32. However, it will be understood that first and second seal elements 16, 18 may be provided without the anti-extrusion springs 30, 32. The first seal element 16 may be defined as an outboard seal element, since in use it will be disposed distal to the pipe opening O and the second seal element 18 may be defined as an inboard seal element, since in use it will be disposed proximal to the pipe opening O. As shown in Figures 1 and 2, the isolation tool 10 further comprises a seal support member, generally denoted 34 which, in the illustrated isolation tool 10 forms part of the seal unit 12. As shown, the seal support member 34 is configured and / or operable to support the first and second seal elements 16, 18 and comprises a base portion 36 upon which the first and second seal elements 16, 18 are disposed and / or carried. The base portion 36 is annular. The seal support member 34 comprises a flange portion 38 which extends radially outwardly from the base portion 36 and is disposed between the first and second seal elements 16, 18. The flange portion 38 is annular and in the illustrated isolation tool 10 takes the form of an annular ring. In the illustrated isolation tool 10, the base portion 36 and the flange portion 38 are integrally formed. As shown in Figures 1 and 2, the flange portion 38 is tapered, being thinner at its radially outmost surface than its base. However, it will be understood that the flange portion may alternatively not be tapered. As described above, the isolation tool 10 comprises a seal actuation arrangement 20 configured and / or operable to urge the first and second seal elements 16, 18 into sealing engagement or enhanced sealing engagement with the wall W of the pipe P, the seal actuation arrangement 20 comprising the first piston 22 configured and / or operable to move in the first direction A and the second piston 24 configured and / or operable to move in the second, opposing, direction B. As shown for example in Figure 2, the first piston 22 is operatively associated with the first seal element 16. The first piston 22 may be defined as an outboard piston. The first piston 22 is configured and / or operable to move in said first direction A so as to urge the first and second seal elements 16, 18 into sealing engagement, or further sealing engagement, with the wall W of the pipe P (as shown, said first direction A being towards the first and second seal elements 16, 18). A first piston chamber 40 (shown most clearly in Figures 5 and 5A) is provided, the first piston chamber 40 between, e.g. formed between, the first piston 22 and the body 28. The first piston chamber 40 is configured to receive an actuation fluid, e.g. hydraulic fluid, so as to urge the first piston 22 in said first direction A. A first piston cap 42 is also provided, the first piston cap 42 configured and / or operable to form an end of the first piston chamber 40, the first piston 22 forming the other end of the first piston chamber 40. The first piston cap 42 is configured and / or operable to prevent leakage of the actuation fluid from the first piston chamber 40. As shown most clearly in Figure 2, the first piston cap 42 comprises annular grooves 44, each configured to receive a seal element 46. As shown, a retention nut 48 is also provided, the retention nut 48 configured and / or operable to retain the first piston cap 42 in place. The retention nut 48 is disposed on the body 28 outboard of the first piston cap 42. The isolation tool 10 further comprises a first pressure head 50, which in the illustrated isolation tool 10 is coupled to the first piston 22. The first pressure head 50 is operatively associated with the first seal element 16 and is configured and / or operable to engage the first seal element 16. The first pressure head 50 may be defined as an outboard pressure head. In use, movement of the first piston 22 in said first direction A moves the first pressure head 50 in said first direction A. As shown for example in Figure 2, the second piston 24 is operatively associated with the second seal element 18. The second piston 24 may be defined as an inboard piston. The second piston 24 is actuable independently of the first piston 22, the second piston 24, when actuated, configured and / or operable to move in said second direction B so as to urge the first and second seal elements 16, 18 into sealing engagement, or further sealing engagement, with the wall W of the pipe P (as shown, said second direction being towards the first and second seal elements 16, 18). A second piston chamber 52 (shown in Figures 6 and 6A) is provided, the second piston chamber 52 provided between, e.g. formed between, the second piston 24 and the body 28. The second piston chamber 52 is configured to receive an actuation fluid, e.g. hydraulic fluid, so as to urge the second piston 52 in said second direction B. The isolation tool 10 further comprises a second pressure head 54, which in the illustrated isolation tool 10 is coupled to the second piston 24. The second pressure head 54 is operatively associated with the second seal element 18 and is configured and / or operable to engage the second seal element 18. The second pressure head 54 may be defined as an inboard pressure head. In use, movement of the second piston 24 in said second direction B moves the second pressure head 54 in said second direction B. As shown, the seal support member 34 is supported by the first and second pistons 22, 24. First and second pressure heads 50 and 54 are mounted on the pistons 22 and 24, respectively. It will be understood that the isolation tool 10 may be operable in two different modes in order to actuate the seal arrangement 14. In a first mode, which may be defined as an upstream mode, the first piston 22 is actuated to move in said first direction A to cause actuation of both the first and second seal elements 16, 18. More particularly, in this first mode, movement of the first piston 22 in said first direction A moves the first pressure head 50 in said first direction A. This in turn may cause the first seal element 16, the seal support member 34 and the second seal element 18 to move in said first direction A, such that the first and second seal elements 16, 18 are axially compressed between the first pressure head 50 and the second pressure head 54. This in turn may cause the first and second seal elements 16, 18 to radially expand into engagement or further engagement with the wall W of the pipe P. In a second mode, which may be defined as a downstream mode, the second piston 24 is actuated to move in said second direction B to cause actuation of both the first and second seal elements 16, 18. More particularly, in this second mode, movement of the second piston 24 in said second direction B moves the second seal element 24, the seal support member 34 and the first seal element 22 in said second direction B, such that the first and second seal elements 16, 18 are axially compressed between the first pressure head 50 and the second pressure head 54. This in turn may cause the first and second seal elements 16, 18 to radially expand into engagement or further engagement with the wall W of the pipe P. Thus, the configuration of the isolation tool 10, which facilitates operation in either said first mode or second mode as required, permits the isolation of either an upstream or downstream section of the pipe P to be achieved without the requirement to locate the seal unit 12 in a particular orientation, or to remove and redress the isolation tool 10. Rather, isolation of the upstream section of the pipe P can be achieved simply by selecting to operate in the first mode and isolation of the downstream section of the pipe P can be achieved simply by selecting to operate in the second mode. Moreover, the configuration of the isolation tool 10 permits selfenergisation of the first and second seal elements 16, 18 in both first and second modes. The isolation tool 10 further comprises a fluid communication arrangement (not shown) for controlling the supply and / or venting of the fluid, e.g. actuation fluid, from the first and / or second piston chambers 40, 52. In the isolation tool 10, the fluid communication arrangement comprises one or more fluid communication passages (not shown) in, e.g. formed in, the body 28. The fluid communication arrangement may comprise or define “set” porting and separate “unset” porting. Alternatively, a single communication passage may be utilised to both supply and vent from the first piston chamber 40 and a single communication passage may be utilised to both supply and vent from the second piston chamber 52. As shown in Figures 1 and 2, the isolation tool 10 comprises a release arrangement, generally denoted 56, configured and / or operable to reconfigure the seal unit 12 so that the seal with the wall W of the pipe P is released. The release arrangement 56 is configured and / or operable to urge the first piston 22 in the second direction B and / or the second piston 24 in the first direction A so as to push the pistons 22, 24 apart and release the axial compression force on the seal arrangement 14. The release arrangement 56 comprises an array of actuators 58 which in the illustrated isolation tool 10 take the form of hydraulic pistons. Referring now also to Figure 2A, 5A and 6A of the accompanying drawings, the isolation tool 10 further comprises a fluid communication arrangement, generally denoted 60 (shown in Figure 2A), configured and / or operable to communicate a fluid, e.g. a test fluid, to an annulus ANN (shown most clearly in Figures 5A and 6A) defined between the first and second seal elements 16, 18 when the first and second seal elements 16, 18 are engaged with the pipe P. The annulus ANN may be defined as a test annulus, since it may facilitate integrity testing of either or both of the first and second seal elements 16, 18 and / or may facilitate testing of a pipe connection, e.g. a weld. As shown in Figure 2A, the fluid communication arrangement 60 comprises a fluid communication passage 62 in, e.g. formed in, the seal support member 34, more particularly the flange portion 38. The fluid communication passage 62 is configured and / or operable to communicate the fluid, e.g. the test fluid, to the annulus ANN. The fluid communication arrangement 60 further comprises a fluid conduit 64 configured and / or operable to communicate the fluid, e.g. test fluid, from a fluid source (not shown) to the fluid communication passage 62 in the seal support member 34. In the illustrated isolation tool 10, the fluid conduit 64 is formed in the isolation tool 10 but it will be understood that the fluid conduit 64 may alternatively or additionally comprise a fluid line such as a hydraulic line or the like. As described above, and referring again in particular to Figure 1, the isolation tool 10 comprises a launcher arrangement, generally denoted 66, configured and / or operable to deploy the seal unit 12 into the pipe P. The isolation tool 10 is also configured and / or operable so that the seal unit 12 is pivotable relative to the launcher arrangement 66 such that the seal unit 12 can be located in either an upstream or downstream location relative to the opening O in the pipe P. The seal unit 12 may for example be defined as bi-directional. As shown, the launcher arrangement 66 comprises a clevis 68, comprising clevis plates 70, a clevis pin 72 and bearing pads 74. The body 28 is configured for mounting on the clevis 68 and comprises or defines a padeye 76 mountable on the clevis pin 72. The isolation tool 10 further comprises an actuator arrangement, generally denoted 78, configured and / or operable to pivot the body 28 relative to the launcher arrangement 66. In the illustrated isolation tool 10, the actuator arrangement 78 comprises a hydraulic piston 80 coupled at a proximal end to the launcher arrangement 66 and at a distal end to the body 28. In use, extension of the piston 80 pivots the body 28 about the clevis pin 72. Referring now also to Figures 3 and 4 of the accompanying drawings, the isolation tool 10 further comprises a swivel, generally denoted 82. The swivel 82 is configured and / or operable to permit fluid communication to the seal unit 12 while at the same time permitting the seal unit 12 to pivot relative to the launcher arrangement 66. As shown in Figure 3, the swivel 82 is disposed at or adjacent to the clevis pin 76. As shown in Figure 4, the swivel 82 comprise a core 84 and a rotatable ring 86, the rotatable ring 86 being rotatable relative to the core 84. The swivel 82 comprises a fluid communication arrangement 88 configured and / or operable to maintain fluid communication when the seal unit 12 pivots. A seal arrangement 90 is provided to maintain sealing integrity between the core 84 and the rotatable ring 86 when the seal unit 12 pivots. In the illustrated isolation too 10, the seal arrangement 90 comprises low RPM, high pressure rotational seals 92. Beneficially, the seals 92 permit the swivel 82 to turn with minimul friction and no or negligible pressure loss. Operation of the isolation tool 10 will now be described with reference in particular to Figures 1 and 2, and also now Figures 5, 5A, 6 and 6A of the accompanying drawings. As described above, in the illustrated method the opening O is formed by a hot tapping process. First, a branch or tee connection T is attached to the pipe P. The connection T may be welded or mechanically secured to the pipe P. A valve arrangement V is then fitted to the connection T. In the arrangement shown in Figure 1, the valve arrangement V takes the form of a hot tap valve, although it will be understood that other valve arrangement V may take other suitable forms. The valve arrangement V is reconfigurable between a closed configuration in which a throughbore B of the valve arrangement V is closed and an open configuration in which the throughbore B is open. When it is desired to form the opening O in the pipe P, the valve arrangement V is configured in, or reconfigured to, its open configuration so as to permit a drilling tool (not shown), known as a hot tapping tool, to be deployed through the connection T and through the wall of the pipe P. Once the opening O through the wall of the pipe P has been formed, the drilling tool is removed and the valve arrangement V reconfigured to its closed configuration, ready for deployment of the isolation tool 10. When the isolation tool 10 is to be deployed, the valve V is reconfigured to its open configuration and the isolation tool 10 moved into the pipe P. On location within the bore of the pipe P, the seal unit 12 is pivoted from an initial in-line orientation used to insert the seal unit 12 through the valve V and the opening O to the perpendicular or substantially perpendicular orientation which aligns or substantially aligns with the axis of the pipe P. It will be recognised that the insertion and retraction of the seal unit 12 may be achieved using any suitable means, including amongst other things a described hot tap machine, stem bar, hydraulic or pneumatic cylinder, lead screw, rack and pinion. Figures 1, 5 and 5A illustrate the first mode of operation of the isolation tool 10, in which the isolation tool 10 is deployed into an upstream section of the pipe P. In this configuration, the opening O and workings are in the isolated section of the pipe P. This allows the isolated section to be vented and purged through the launcher arrangement and / or the pressure to be equalised through the same. As the load path passes into the clevis via the bearing pads, it is most suitable for high pressure applications. As this has minimum components in contact with the fluid during the isolation, it is also particularly suited to corrosive and / or or high / low temperature applications. As shown in Figures 5 and 5A, fluid, e.g. hydraulic fluid, is directed into the first piston chamber 40 to urge the first piston 22 and the first pressure head 50 in the first direction A. The movement of the first pressure head 50 axially compresses the first and second seal elements 16, 18 so that they expand radially into engagement with the wall of the pipe P, the seal support member 34 being free to move along the body 28, so ensuring the compression load is applied equally to both of the seal elements 16, 18. As shown, by virtue of inter-engaging shoulders on the second piston 24 and the second pressure head 54, and inter-engaging shoulders on the second piston 24 and the body 28, the second pressure head 54 is securely restrained on the body 28. As shown, the second pressure head 54 also bears on the clevis 68 of the launcher arrangement 66, which in turn transfer the loads to the pipe P through the bearing pads 74. As noted above, the cavity 26 within the seal unit 12 can be vented, the force resulting from the isolated pressure Pf from the fluid f acting on the first pressure head 50 acting to facilitate seal self-energisation due to the difference in pressure head area vs the seal area exposed to the pressure Pf. As the seal support member 34 is free to move, both first and second seal elements 16, 18 are energised. For higher pressure systems, this self-energisation resulting from the differential pressure is sufficient to retain the seal activation. The annulus ANN between the first and second seal elements 16, 18 is connected to a control console (not shown) which permits the annulus ANN to be pressurised and vented to test either or both of the first and second seal elements 16, 18. It will be noted also that the base portion 36 of the seal support member 34 acts to limit the stroke so of the even if one of the seal elements 16; 18 fails, the load will be maintained on the other seal elements 16; 18 making the seals independent (this feature also applies to the second, downstream, mode described further below. Figures 6 and 6A of the accompanying drawings illustrate the second mode of operation of the isolation tool 10, in which the isolation tool 10 is deployed into a downstream section of the pipe P. In this mode, the opening O and workings are disposed in the flow in the pipe P. This allows a bypass to be provided through the same opening as the isolation tool 10. The bypass connection can be through the launcher arrangement 66, a 3 way tee or spherical tee. A small bore hot tap (not shown) may be required to vent and purge the isolated section and / or the pressure to be equalised through the same. To facilitate this, a through port can be provided in the body 28 to facilitate venting and purging of the isolated section via the isolation tool 10. In this mode, the load path passes into the clevis 68 and pin 72. In this mode, the second piston 24 and the second pressure head 54 are displaced in the second direction B by introducing fluid, e.g. hydraulic fluid into the second piston chamber 52. Movement of the second pressure head 54 axially compresses the first and second seal elements 16, 18. As before, albeit in the opposite direction, the seal support member 34 is free to move along the body 28 so ensuring the compression load is applied equally to both of the first and second seal elements 16, 18. It will be recognised that various modifications may be made without departing from the scope of the invention as defined in the claims. For example, the components mounted on the body 28 of the seal unit 12, e.g. the first and second seal elements, 16, 18, the seal support member 34, the first and second pressure heads, may be configured as an assembly or kit. Beneficially, this permits the components of the seal unit 12 to be adapted to suit different pipe bores or conditions.

Claims

1. An isolation tool for use in isolating a section of a pipe, the isolation tool comprising:a seal unit configured for location in the section of pipe to be isolated, the seal unit comprising:a seal arrangement comprising at least a first seal element and a second seal element, the first and second seal elements configured and / or operable to engage a wall of the pipe; anda seal actuation arrangement configured and / or operable to urge the first and second seal elements into sealing engagement with the wall of the pipe,wherein the seal actuation arrangement comprises a first piston and a second piston,wherein the first piston is configured and / or operable to move in a first direction so as to actuate both the first and second seal elements, andwherein the second piston is configured and / or operable to move in a second, opposite, direction so as to actuate both the first and second seal elements.

2. The isolation tool of claim 1, wherein the seal unit is configured and / or operable for location in the section of pipe via a single opening in the wall of the pipe.

3. The isolation tool of claim 1 or 2, wherein the isolation is operable in a first mode, in which the first piston is actuated to move in said first direction to cause actuation of both the first and second seal elements and a second mode in which the second piston is actuated to move in said second direction to cause actuation of both the first and second seal elements.

4. The isolation tool of claim 1, 2 or 3, wherein at least one of the first seal element and the second seal element comprises a bi-directional seal element.

5. The isolation tool of any preceding claim, wherein at least one of the first seal element and the second seal element comprises an elastomeric seal element.

6. The isolation tool of any preceding claim, wherein at least one of the first seal element and the second seal element comprises a compression seal element.

7. The isolation tool of any preceding claim, wherein at least one of the first seal element and the second seal element is adapted to be self-energising.

8. The isolation tool of any preceding claim, wherein the first seal element defines an outboard seal element and the first seal element defines an inboard seal element.

9. The isolation tool of any preceding claim, wherein the first piston is configured and / or operable to move in said first direction so as to urge the first and second seal elements into sealing engagement, or further sealing engagement, with the wall of the pipe, said first direction being towards the first and second seal elements.

10. The isolation tool of any preceding claim, comprising a first piston chamber, wherein the first piston chamber is configured and / or operable to receive an actuation fluid, e.g. hydraulic fluid, so as to urge the first piston in said first direction.

11. The isolation tool of any preceding claim, wherein the second piston is configured and / or operable to move in said second direction so as to urge the first and second seal elements into sealing engagement, or further sealing engagement, with the wall of the pipe, said second direction being towards the first and second seal elements.

12. The isolation tool of any preceding claim, wherein the second piston is actuable independently of the first piston.

13. The isolation tool of any preceding claim, comprising a second piston chamber, wherein the second piston chamber is configured and / or operable to receive an actuation fluid, e.g. hydraulic fluid, so as to urge the second piston in said second direction.

14. The isolation tool of any preceding claim, wherein the first piston defines an outboard piston and the second piston defines an inboard piston.

15. The isolation tool of any preceding claim, comprising a first pressure head.

16. The isolation tool of claim 15, wherein the first pressure head is coupled to or forms part of the first piston, wherein the first pressure head is configured and / or operable to engage the first seal element when the first piston moves in said second direction so as to urge the first and second seal elements into sealing engagement, or further sealing engagement, with the wall of the pipe.

17. The isolation tool of any preceding claim, comprising a second pressure head.

18. The isolation tool of claim 17, wherein the second pressure head is coupled to or forms part of the second piston, wherein the second pressure head is configured and / or operable to engage the second seal element when the second piston moves in said second direction so as to urge the first and second seal elements into sealing engagement, or further sealing engagement, with the wall of the pipe.

19. The isolation tool of claim 17 or 18, when dependent on claim 15, wherein the first pressure head defines as an outboard pressure head and the second pressure head defines an inboard pressure head.

20. The isolation tool of any preceding claim, comprising a body, wherein the seal arrangement and the seal actuation arrangement are disposed on and / or carried by the body.

21. The isolation tool of any preceding claim, comprising a seal support member, body, wherein the first and second seal elements are disposed on and / or carried by the seal support member.

22. The isolation tool of claim 21, wherein the seal support member comprises at least one of:a base portion, wherein the first and second seal elements are disposed on and / or carried by the base portion; anda radially extending flange portion, wherein the flange portion is disposed between the first and second seal elements.

23. The isolation tool of any preceding claim, comprising a swivel.

24. The isolation tool of claim 23, wherein the swivel is configured and / or operable to permit fluid communication to the seal unit while at the same time permitting the seal unit to pivot.

25. The isolation tool of claim 23 or 24, wherein the swivel comprises: a core; anda ring rotatable relative to the core.

26. The isolation tool of any preceding claim, comprising a release arrangement configured and / or operable to reconfigure the seal unit so that the seal with the wall of the pipe is released.

27. The isolation tool of claim 26, wherein the release arrangement comprises an actuator arrangement comprising one or more actuators configured and / or operable to urge the first piston in the second direction and / or urge the second piston member in the first direction.

28. The isolation tool of any preceding claim, comprising a fluid communication arrangement configured and / or operable to communicate a fluid, e.g. a test fluid, to an annulus defined between the first and second seal elements when the first and second seal elements are engaged with the pipe.

29. The isolation tool of claim 28, when dependent on claim 21, wherein the fluid communication arrangement comprises a fluid communication passage in, e.g. formed in, the seal support member.

30. The isolation tool of any preceding claim, wherein the isolation tool comprises or is configured for coupling to a launcher arrangement configured and / or operable to deploy the seal unit into the pipe.

31. The isolation tool of claim 30, wherein the isolation tool is configured and / or operable so that the seal unit is pivotable relative to the launcher arrangement such that the seal unit can be located in either an upstream or downstream location relative to the opening in the pipe.

32. A method for isolating a section of a pipe, using the isolation tool of any preceding claim.

Images