The present invention relates to a fixing and to a method for applying a fixing. In a particular embodiment of the invention, the fixing comprises a threaded stud or bolt typically connecting two sides of a joint, but plain fixings such as unthreaded rods can also be used. In some embodiments, the connection is a flanged connection, typically between two sections of pipe or between a flanged pipe and another member such as a container, but the fixing can be applied across other kinds of connections within the scope of the invention.

One important factor in such connections is the force applied to the fixing across the connection, and particularly the tension applied to the fixing. Inconsistent forces can lead to weakness in the connection. Typically threaded fixings are made up to a particular tension. One way of doing this is by tightening nuts on the threaded stud or bolt using a torque wrench. This is a widely used method but is inaccurate (within around 15%) as the measured torque applied to the nut on a threaded stud does not necessarily relate directly to the tension in the stud, and can be artificially affected by friction between the stud and the bolt hole, corrosion, damage, thread profile and other factors unrelated to the actual tension experienced by the stud extending across the connection. Also, studs of the same diameter tensioned to the same measured torque setting at the nut can often exhibit different tensions in the stud, as a result of local changes in resilience, cross-section, thread profile, frictional differences encountered as a result of the surfaces in each bolt hole, and material composition of the studs.

A more accurate tensioning method is to apply the nut to the stud, and then apply a hydraulic bolt tensioner to the stud, to preload the shaft of the stud to stretch the shaft to a particular tension higher than the desired final tension by around 10%, and then to hand tighten the nut against one of the members being connected before removing the hydraulic tensioner. When the hydraulic tensioner is removed, the stretched out threaded stud relaxes to a lower tension and is held in that tension by the hand tightened nut (or other part) butting against the member. This is a more accurate setting method, and can achieve the required tension in the stud with an accuracy of between 5-10%, but requires over-tensioning the shaft by a subjective amount, and still includes the subjective hand tightening step that leads to lack of consistency in the final tension achieved.

According to the present invention there is provided a fixing for making a connection between two members, the fixing having a shaft extending across the connection, a stop member on the shaft, a fixing body adapted to receive the shaft, and a wedge device adapted to be moved relative to a part of the fixing body, wherein the movement of the wedge device changes the separation between the fixing body and the stop member thereby changing the tension in the shaft.

The invention also provides a method of applying a fixing extending across a connection, wherein the fixing has a shaft, and wherein the method includes receiving the shaft in a fixing body, providing a stop member on the shaft, providing a wedge device moveable relative to a part of the fixing body, and moving the wedge device relative to the fixing body, whereby the tension in the shaft is changed by the movement of the wedge device to change the separation between the fixing body and the stop member.

The invention also provides a method of connecting two members, the method comprising connecting a fixing between the members, the fixing having a shaft extending across the connection between the members, and wherein the method includes receiving the shaft in a fixing body, providing a stop member on the shaft, providing a wedge device moveable relative to a part of the fixing body, and moving the wedge device relative to the fixing body, whereby the tension in the shaft extending across the connection is changed by the movement of the wedge device to change the separation between the fixing body and the stop member. Typically the wedge device comprises a wedge located between the stop member and the fixing body, which is arranged to move relative to the fixing body and/or the stop member. Typically the fixing body is adapted to move axially with respect to the shaft.

Typically the fixing applies tension to the shaft and urges the movement of the fixing body axially along the shaft, to increase or decrease the tension in the shaft. In other embodiments, the axial movement of the fixing body along the axis of the shaft applies a compressive force to one of the members, which increases or decreases in accordance with the movement of the wedge. Optionally the movement of the wedge device primarily has a radial component relative to the axis of the shaft. Optionally the movement of the wedge device has an axial component relative to the axis of the shaft. Typically the radial component of movement of the wedge device is greater than the axial component, so that a mechanical advantage is created by radial movement of the wedge device which urges axial movement of the fixing body with a higher force (but typically over a shorter displacement) than the radial component of movement.

Typically movement of the wedge device expands (or contracts) the axial dimensions of the fixing body, thereby reacting against the stop member to change the force applied by the fixing. For example, expansion of the fixing body as a result of driving the wedge device typically reacts against the fixed stop member to increase the tension in the shaft.

Typically the connection can be made between two adjacent flanges on pipe ends. The fixings are typically threaded and can comprise bolts or threaded studs, but unthreaded fixing such as rods (optionally with a roughened or textured outer surface) can suffice. The bolts or threaded studs can extend between the flanges. However, other kinds of connection can be made using the fixing, for example, any bolted connection, where a nut travels on the shaft of a threaded stud or bolt. Typical examples include replacements for high strength bolts in e.g. engines, motors, turbines, brakes, valves, and mountings therefor, drive shaft mountings, gear boxes, compressors, pumps, crushes and presses, anchors and mining equipment, including oil and gas well equipment such as Kelly drives and mountings therefor, and high strength valves such as blow out preventers. Embodiments of the invention are also useful for fastening in place large structures requiring multiple bolts tensioned to a consistent level, such as pressure tanks, chemical reactors, storage tanks, heat exchangers. Securing and fixing of power generation equipment such as wind, wave and water turbines is also a useful application for certain embodiments of the invention. The threaded nuts etc. movable on the threads of the studs etc. serve as a primary tensioning mechanism and can be operated to apply axial force to close the connection initially, for example allowing initial tensioning to the limit of the tools being used, and typically the wedge device provides a secondary tensioning mechanism, which can be used to apply additional tension to the fixing after the initial tensioning step.

The stop member on the fixing can optionally be threaded, and can optionally comprise a nut, optionally on each end, but a radial clamp device adapted to grip the rod and resist axial sliding along the shaft can suffice.

Optionally the fixing can incorporate a tension indicator. Optionally the tension indicator can be provided at least partially within the shaft of the fixing.

Typically the connection has an axis and the flanges typically extend perpendicularly with respect to the axis of the connection (e.g. the axis of the shaft). Typically one fixing body is applied on each side of the connection, e.g. on the outer surfaces of opposite flanges, with one part of each fixing (e.g. a foot portion) bearing on the outer surface of the opposing flanges and forcing them together.

The shaft can comprise a threaded shaft extending through plain bolt holes in the members being connected. Optionally the socket in the fixing can be threaded or a nut or other cooperating fixing can be used to react against the threaded shaft.

Typically the fixing body comprises a collar with a bore extending axially in parallel to the axis of the connection, and the collar can typically be radially spaced in relation to the axis of the connection, allowing the collar to receive and retain the fixing such as a bolt or threaded stud or the like, which can extend parallel to the axis of the connection, but is typically spaced radially therefrom. Typically a nut is threaded onto the bolt or stud on the other side of the connection, and the threaded action of the nut on the stud or bolt (typically against the fixing) can typically provide axial force to close the connection. Typically the bore of the collar is radially spaced from the axis of the connection, so that in a flanged connection, the bolt or stud passes outside the flanges, without engaging them. Typically the fixing body has a foot. Typically the foot applies axial force to e.g. the flanges or other connected parts.

In certain embodiments of the invention, the fixing can be a tensioning device. Optionally the fixing can be located between two fixing bodies spaced apart on each side of the connection, and optionally on the outer faces of the connected members, so that tensioning the fixing draws the fixing bodies together to make up the connection. In simpler embodiments, a single fixing is sufficient, but in certain embodiments, two fixing bodies are typically spaced apart along the axis of the shaft, and the shaft extends between them, with the wedge device operating to pull or push the fixing bodies towards one another. In certain embodiments the fixing is tensioned in an axial direction with respect to the connection.

In certain embodiments of the invention, two, or more than two fixings are provided, typically in even numbers, but in certain embodiments an odd number of fixings greater than two (e.g. 3, 4, 5, 6, or more) can be provided. In flanged applications, typically the fixings are equi-distantly spaced around the circumference of the flange. Spacing the fixings at equal distances around the circumference of the flange to be clamped equalises the compression around the flange. Typically, fixings are applied on opposite ends of each bolt passing through the flanges. Typically the fixing permits the position of the foot against the outer face of the flange to be adjusted, optionally at the mid point between adjacent bolts. Optionally the fixing can be used instead of the bolts passing through the bolt holes in the flanges, but in some embodiments, the fixing of the invention can be used in addition to the pre-existing bolts making up a connection.

Typically the bores of the collars are aligned with one another, and are connected by means of the threaded stud or bolt etc.

Typically the fixing bodies are connected with nuts or other fasteners applied to the threaded studs or bolts, etc. to loosely connect the fixing bodies together before the fixing is tensioned across the connection. After the fixing is applied across the connection, the nuts or other fasteners can be tensioned at one or both ends of the stud to engage the outer faces of the flange (or other member) on each side of the connection.

In flanged applications, when the foot portion has been positioned against the flange on each side of the connection, optionally in between adjacent bolts, and the nuts on the threaded stud have been tensioned in order to loosely clamp each fixing in place across the flanged connection, this process is repeated until the required number of fixing bodies have been applied across the flanged connection. Typically, as many fixing bodies as possible will be applied across the flanged connection, typically at regular circumferential spacing, since this permits the apparatus of the invention to apply a generally even clamping force circumferentially around the flanges. Optionally, it will be sufficient for one fixing to be applied in between each adjacent pair of bolts. The connection is typically made up by tensioning the stop members on the shafts of the fixings.

Optionally the wedge device has an aperture to receive the shaft. Optionally the aperture is oval so that the wedge device can move relative to the shaft so that the shaft translates along the long axis of the oval aperture, from one end towards the other. Optionally the wedge device has a long axis and the long axis of the oval aperture is parallel to the long axis of the wedge device. Optionally the aperture is closed and the wedge device surrounds the fixing shaft. In certain embodiments the wedge device can be U- or horseshoe shaped, with an open-ended aperture.

Typically the wedge device incorporates at least one wedge tapering from a thick end to a relatively thinner end.

Typically the wedge moves in a radial direction relative to the shaft, but since the wedge has a tapered face the radial movement of the wedge imparts an axial force to the shaft.

In certain embodiments of the invention the wedge device can incorporate more than one wedge, for example 2, 3, 4, 5 or more wedges. Optionally where more than one wedge is provided in the wedge device, more than one wedge is movable relative to the stop member and/or the fixing in order to change the tension in the shaft.

Optionally where more than one wedge is provided in the wedge device, the faces can both be tapered (i.e. non-perpendicular to the axis of the shaft). Optionally the tapered faces meet at an apex of the wedge, but this is not necessary, and many useful embodiments of the invention have tapered faces which are truncated before they actually meet in an apex at the thin end. Typically each wedge can have the same taper on opposing faces with respect to the axis of the shaft, but in certain embodiments the can be tapered at different angles with respect to the axis of the shaft.

In certain embodiments, however, the two or more wedges can optionally have different degrees of taper between their thick and thin ends. Hence, the same movement of two different wedges in the wedge device can optionally induce different tension changes in the shaft depending on the degree of taper in the different wedges. For example, a first wedge could have a steep taper and a second wedge could have a relatively shallower taper. Radial movement of the first wedge by a given amount would induce a larger change in the tension of the shaft than the movement of the second wedge by the same amount, because of the differential in the taper between the two wedges. Accordingly, in operation, steeper wedges can be moved first, to take up slack and conduct coarse movements at low tension in the shaft, for example, to lock up the wedge device in place at the commencement of the tensioning operation. Optionally, after the movement of the steeper wedges take up the slack in the wedge device, the shallower wedges can be moved to induce smaller tension changes at higher tension in the shaft, typically with greater accuracy. Optionally once the shallower wedge has been moved to the limit of its tension, sequentially shallower wedges can be moved to induce sequentially smaller changes in the tension in the shaft, until the desired tension is reached.

Such embodiments of the invention permit relatively fine and accurate adjustment of the tension in the shaft up to very high tensions, without large radial movements of the wedge devices, which might be difficult in certain applications with limitations on the possible travel of the wedges.

Typically at least one face of the wedge is angled with respect to the axis of the shaft. For example, at least one face (and typically each face) of at least one wedge is set at an acute angle with respect to the shaft. Optionally the angles of each face relative to the axis are equal, and the wedge takes the form of an isosceles triangle, or a truncated version of the same. However, this is not necessary and useful wedges can be formed with opposing faces having different angles, and in such cases the wedge can optionally take the form in cross section of a scalene triangle, or a truncated version thereof. In certain embodiments, it is only necessary for one of the faces of the wedge device to be set at an acute angle, while the other face is generally perpendicular to the axis of the shaft, so that the wedge takes the form of a right angle triangle, or a truncated version thereof.

Optionally where more than one wedge is provided, the wedges are arranged in a stack with the front face of one wedge engaging the back face of an adjacent wedge, but this is not necessary and the wedges can be interspaced by spacers if desired. Typically the engaging faces of the wedges are mutually parallel so that the movement of the wedges including a radial component causes the faces of one wedge to slide against adjacent faces that are parallel and so support the wedge against deformation during the movement of the wedge. Strictly perpendicular movement of the wedge relative to the axis of the shaft is not the only way of altering the tension in the shaft, and radial movements of the wedges that are not absolutely perpendicular, i.e. which incorporate axial components of movement in addition to radial components, are also capable of changing the tension and functioning in useful embodiments of the invention. Optionally the wedges can be arranged in pairs, on opposite sides of the axis of the shaft, typically in a symmetrical arrangement above and below the axis of the shaft. Optionally each pair of wedges can be linked to move together, so that typically force applied to one of the wedges in a pair is applied through a linkage to the other wedge in the pair. Typically the linkages can comprise bolts or other threaded fasteners provided with nuts or the like for applying forces to the paired wedges (or to one of them).

Typically one face (e.g. the inner face with respect to the connection) of the wedge (typically the face that is facing the fixing) is set at a different angle to the other face (e.g. the outer face) of the wedge, which typically faces the stop member. The difference between the inner and the outer faces is typically less than 45 degrees from the vertical axis, which is perpendicular to the axis of the connection. Typically an angle of 5-20 degrees is suitable, e.g. 10-15 degrees, and particularly between 5 and 10 degrees, e.g. 5, 6, 7, 8 or 9 degrees.

Typically the outer surface of the fixing is set at the same angle as the inner surface of the wedge device.

Typically the surfaces of the fixing and the wedge device that face the members being connected and the stop member are mutually parallel and are optionally perpendicular to the axis of the connection. Optionally the force applied by each fixing to the member can be adjusted independently of other fixings attached to the member. This can optionally be done by tensioning the main bolt or threaded stud extending axially between the fixing bodies. Optionally the tension can be adjusted independently on each side of the connection. Optionally the force applied at each fixing can be adjusted independently of the other fixings. More than one adjustment device can be provided on a single fixing to apply different tension independently to different parts of the fixing. Typically one adjustment device adapted to move the wedge can comprise a screw threaded bolt or stud having a head that can be turned by a spanner or other driver, typically allowing adjustment of the tension after the fixing has been applied to the members. Optionally the adjustment device can be moved radially relative to the shaft, allowing adjustment of the wedge position, and therefore adjustment of the tension in the shaft, by pure radial movement of the adjustment device, which typically pushes the wedge radially. Therefore, in certain examples of the invention, the adjuster device permits easier adjustment of the axial tension in the shaft by radial movements of screws or other adjustment devices acting on the wedge device.

Optionally the wedge device is driven between the device and the stop member by screw threaded adjuster member such as an adjuster bolt or screw in order to change the relative positions of the two components, and therefore increase or decrease the distance between them, thereby adjusting the tension in the shaft of the fixing. The wedge device can be driven by an adjuster bolt or screw, typically restrained in or on a part of the fixing. Optionally more than one adjuster bolt or screw can act on the wedge device, typically with at least two bolts acting on each wedge. In certain embodiments, each wedge device can optionally be driven by more than two bolts, e.g. 3, 4, 5, 6, 7, or 8 bolts, but typically an even number of bolts is applied in a symmetrical arrangement on the wedge, to drive its movement. The adjuster screw can be housed in a bore (which can typically be at least partially threaded) that is parallel to the sloped faces of the wedge device and (optionally) the fixing body. Optionally the wedge device can be driven by an adjuster screw that is housed within a bore made up of more than one component. The bore housing the adjuster screw can optionally be only partially threaded, for example threaded on only one side, and the threads can optionally be formed on only one of the components. In one embodiment, the bore can optionally comprise a matching pair of recesses on facing walls of two relatively movable components, for example, the collar and the wedge device. The recess on one, e.g. the wall of the collar, can be threaded, and optionally the recess on the other, e.g. the wall of the wedge device can be plain. Typically the plain wall is provided on the member that is movable, and the threads are provided on the member that is fixed. In certain embodiments, this can be reversed, with the plain wall being provided on the fixed member and the threaded wall being provided on the movable member. The thread can be left handed or right handed. Optionally a right handed thread is provided on the moving member. Alternatively, a left handed thread can be provided on a fixed member. Typically the recess on the wall of the wedge device can have a radial protrusion extending into the bore to be driven by a portion of the screw adjuster (e.g. the end of the screw adjuster) so that the axial movement of the screw adjuster in the bore drives the protrusion along the bore. As the half of the bore on the wedge device is plain and unthreaded, the screw adjuster slides on the unthreaded wall of the recess in the wedge device, and moves the wedge device along the axis of the bore, relative to the fixing body.

The different tensioning devices and their adjusters can optionally be combined in a single embodiment, so that one embodiment might have a number of different tensioning options. The fixings can optionally be provided with tension measuring, controlling and/or indicating devices indicating and/or controlling the tension applied to a bolt. Optionally the mechanism can indicate the tension in a readable scale, but in some simpler embodiments, the desired tension can be pre-set before tensioning the bolt, and the bolt can then typically be tensioned up to that level without any reading of the tension until the pre-set tension is reached. Suitable tension controllers are described in US 4,636,120 and US 5,226,765, the contents of which are incorporated by reference, but other tension gauges and indicators can be used instead. The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one embodiment can typically be combined alone or together with other features in different embodiments of the invention.

Various embodiments and aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary embodiments and aspects and implementations. The invention is also capable of other and different embodiments and aspects, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention. In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially of, "consisting", "selected from the group of consisting of, "including", or "is" preceding the recitation of the composition, element or group of elements and vice versa.

All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa.

In the accompanying drawings:

Fig 1 shows a perspective side view of a flanged connection;

Figs 2 and 3 show respective perspective side and sectional views of an alternative design of fixing suitable for use in the flanged connection in Fig 1, in an un-tensioned configuration; and

Figs 4 and 5 show respective perspective side and sectional views of the Fig 2 and 3 fixing in a tensioned configuration;

Fig 6 and 7 show side and perspective views of a second embodiment of a fixing, in an inactive configuration;

Figs 8 and 9 show side and perspective views of the Fig 6 fixing in a first stage of activation; Figs 10 and 11 show side and perspective views of the same Fig 6 fixing in a second stage of activation;

Figs 12 and 13 show side and perspective views of the same Fig 6 fixing in a fully activated configuration;

Figs 14 and 15 are side and plan views of the Fig 12 arrangement;

Figs 16 and 17 are section views through lines A-A and B-B of Fig 15;

Figs 18 and 19 are perspective views of the fixing assembled on a flange joint;

Fig 20 is an exploded view of the Fig 6 fixing;

Figs 21 and 22 are perspective and side views of a third embodiment;

Figs 23 and 24 are perspective and side views of a fourth embodiment;

Figs 25 and 26 are perspective and side views of a fifth embodiment; and

Figs 27 and 28 are perspective and side views of a fifth embodiment in an inactive configuration;

Figs 29 and 30 are perspective and side views of the fifth embodiment in an active configuration; and

Fig 31 is an exploded view of the fifth embodiment.

Referring now to the drawings, Fig. 1 shows a pipeline P having a flanged connection comprising a pair of flanges F which are interconnected by conventional bolts B passing through axial holes in the flanges F so that the bolts B are parallel to but radially spaced from the axis of the pipe P. The bolts B are typically arranged at equal distances around the circumference of the flanges, so as to equalise the clamping pressure they apply. The flanges F have outer faces which are engaged by nuts, and inner faces which typically can have a groove for retaining a gasket adapted to seal the connection.

When the bolts B are to be replaced, the apparatus shown in Fig. 2 can be applied across the connection between the flanges F by the following method. However, in alternative embodiments, the flanges (or other members) can be newly constructed with the fixings of the invention, with a reduced requirement for remedial actions to adjust the bolts. The fixing 15 comprises upper and lower fixing bodies 16a, 16b, which are mirror images of one another typically and are typically interconnected by a threaded shaft or stud 17. Threaded stud 17 typically passes through a bore in a collar portion 18 on each fixing body 16. The bores on the collars 18 are typically aligned. The collars 18 are optionally welded to legs (not shown) that extend axially away from the flanges F. The opposing (facing) ends of the collars 18 typically have a flat inner surface 18i that is perpendicular to the axis of the stud 17. The collars 18 are typically arranged on each side of the connection in a mirror image, so that the inner surfaces 18i face one another and are mutually parallel.

The other (axially outward) face 18f of the collar axially opposite to the inner face 18i is sloped at a typical angle of 6 degrees in this example, with respect to the inner perpendicular faces 18i. The fixing bodies 16 each have a wedge member 40 in the form of a generally oval collar having an oval aperture. The wedge device 40 is tapered in side profile, typically in an opposite arrangement to the collar 18, having a generally perpendicular axially outermost face, with an axially innermost face 40f of the wedge device 40 being tapered at an angle that typically matches the angle of the tapered face 18f of the collar, i.e. 6 degrees. Typically the opposed tapered faces 18f and 40f are pressed against one another (although this is not necessary) so that the sloped faces of the wedge device 40 and the collar 18 slide with a radial and an axial component of relative movement, with the shaft of the stud 17 translating along the oval aperture in the wedge device 40 as a result.

The ends of the stud 17 extending axially beyond the collars 18 are capped with a nut 17n in order to drive the fixing bodies 16 towards one another when the nuts 17n are tightened. Existing bolts B are typically removed from the bolt holes in the flanges F, the fixing 16a is removed from the free end of the fixing 15, and the shaft of the stud 17 is fed through the bolt hole previously occupied by the bolt B. The fixing 16s is then replaced on the shaft of the stud, and the nuts 17n are tightened so that the perpendicular inner faces 18i are pressed against the outer faces of the flanges, with which they are parallel. This process is repeated with additional fixings 15 until each desired bolt hole has a fixing 15. When fixings 15 have been applied across the flange and tensioned typically the tension in the existing studs 17 can be measured by known tension measurement devices (e.g. torque wrenches or in-shaft tension indicators) and monitored as the tension is increased through the fixings 15.

The individual tension applied to each fixing 15 can be modified by adjustment devices. In certain embodiments, each fixing can typically be tensioned independently of other fixings attached to the flange.

The wedge device 40 is driven between two of the components of the device in order to change the relative positions of the two components, and therefore increase or decrease the distance between them, thereby adjusting the tension in the device. The tapered side profile of the wedge device 40 is typically linear and consistent between the ends of the wedge device 40, but this can be varied. The angle of the tapered face of the wedge device 40 in this embodiment is 6 degrees with respect to the axially outermost face of the wedge device. The (inner) face 18i of the collar is typically at the same angle as the outer face of the wedge device 40, i.e. perpendicular to the central axis of the stud 17, and the sloping inner face 40f of the wedge device 40 is pressed against the sloping outer face 18f of the collar 18.

The fixing bodies 16 each have a bore 20 to accommodate an adjuster 23 in the form of a screw or bolt to drive the wedge device 40 down the sloped face 18f of the collar 18. The bore 20 is made up of opposed recesses on the sloped faces 18f and 40f, which combine to accommodate the adjuster 23.

The bore 20 is typically at least partially threaded to receive the adjuster 23, so that rotation of the adjuster 23 in the bore 20 radially drives the wedge device 40, parallel to the axis of the bore 20. The wedge device 40 is typically set in place between the collar 18 and the head 17n of the threaded stud 17, or a nut 17n. Driving the wedge device 40 radially down the slope 18f towards the axis of the pipes by driving the adjuster 23 pushes the thicker end of the wedge device 40 radially inwards, which imparts an axial component of movement to the collar relative to the stationary nut 17n or head of the stud 17, and thereby increases the separation between the collar 18 and the head on the threaded stud 17, and so directly increases the tension in the threaded stud 17 as a result of the stop member in the form of the nut 17n, which prevents further axial separation of the fixing bodies 16, but allows them to move together under the action of the wedge device 40. Conversely, radially retracting the wedge device 40 reduces the tension. Accordingly the tension in the stud 17 can be controlled by turning the adjuster 23, before or after fitting of the fixing 15 to the pipes. Turning the adjuster 23 adjusts the tension on the stud independently of other fixings.

The wedge device 40 typically has its outer thick end near the top of the oval and the narrower inner end near the bottom of the oval aperture and adjacent the inner part of the collar 18. The wedge device is moved along the sloping outer face 18f of the collar by the adjuster 23. The adjuster 23 is typically housed within a bore made up of more than one component. In this embodiment, the bore housing the adjuster 23 is optionally only partially threaded, typically only one side, and the threads are optionally formed on only one of the components. In this embodiment, the bore comprises a matching pair of recesses on the opposed sloping walls of the collar 18 and the wedge device 40. The recess on the sloped outer wall 18f of the collar 18 can optionally be threaded, and optionally the recess on the opposing inner wall of the wedge device 40 can be plain. Typically the recess on the wall of the wedge device 40 can have a radial protrusion 41 extending into the bore at the lower end of the bore 20, to be driven by a portion of the screw adjuster 23 (e.g. the end of the screw adjuster) so that the axial movement of the screw adjuster 23 in the bore drives the protrusion 41 axially along the bore, relative to the collar 18. As the recess on the inner face of the wedge device 40 is plain and unthreaded, the screw adjuster 23 slides on the unthreaded recess in the inner wall of the wedge device 40, and drives the wedge device 40 along the axis of the bore, along the sloping outer face 18f of the collar 18, while reacting against the threaded portion of the bore. The stud 17 remains within the oval aperture of the wedge device 40 and moves from the outer end of the aperture to the inner end, as the wedge device 40 moves down the sloped face 18f. Because of the sloped faces 18f and 40f of the collar 18 and the wedge device 40, driving the screw adjuster 23 to move the wedge device 40 down the outer sloped face 18f of the collar 18 moves the flat and perpendicular outer face of the wedge device 40 parallel to the axis of the stud 17, thereby increasing the distance between the nuts 17n on the stud 17 and tensioning the stud 17. Figures 2 and 3 show the device 15 in an un-tensioned configuration, in which the wedge device 40 is in an outer position, and the stud 17 is at an inner end of the oval aperture 42. Figures 4 and 5 show the device 15 in a tensioned configuration, in which the wedge device 40 has moved down the sloped outer face of the collar 18f to rest in an inner position, nearer to the flange, and the stud 17 is at an outer end of the oval aperture 42. The movement down the slope 18f has moved the wedge device 40 with a radial and an axial component, so the outer faces of each of the wedge devices 40f has pushed the nuts 17 further away from one another in order to tension the stud. Turning the adjuster 23 therefore adjusts the tension on the stud independently of other fixings. Tension can be applied or relieved by the adjuster 23.

The adjuster 23 typically has an exposed head that can be turned by a spanner or other driver, typically allowing adjustment of the tension after the fixing has been applied to the flanges.

In a similar manner, the wedge device can optionally be driven between other components on different embodiments. However, it is typical that the wedge device is driven between the collar of the device and the nut on the stud in order to change the relative positions of the two components, and increase or decrease the distance between them, thereby adjusting the tension in the device. Optionally any embodiment can incorporate a mechanism to monitor or control the tension in any of the bolts and/or in any of the adjusting screws, for example in the axial bolts 17 connecting the fixing bodies across the flanges. Suitable tension controllers are described in US 4,636,120 and US 5,226,765, the contents of which are incorporated by reference, but other tension gauges and indicators can be used instead. Typically the bolts 17 are pre-loaded to a desired tension suitable for the flange, and then tensioned in place until the controller trips the indicator to indicate to the operator that the bolt 17 has reached the required tension. Typically the gauges can be incorporated within the studs 17 in a configuration having their strain adjusters on an external surface, so that the pre-load tension can be checked, and/or adjusted after the apparatus has been put in place on a flange, for example, in a 5 year inspection. Optionally the tension in studs 17 can additionally or alternatively be measured by means of torque wrenches or the like. More than one tensioning device can be provided on a single device to apply different tension independently to different parts of the device.

Typically a wedge device can be applied to each fixing body, but it is sufficient for a single fixing body on one side of the connection to have a wedge device. Typically the wedge device is pressed against the fixing body, but the two components with the sloping surfaces can be spaced axially apart across the connection.

Embodiments of the invention are suitable for working on flanges, and tensioning bolts connecting flanges, but different embodiments are suitable for tensioning other connections and fixings, such as engine mountings, turbine hubs, and essentially any bolted connection.

The ability to tension the fixings with simple hand operated tools such as spanners etc. applied to the outside of the fixings is useful as it allows high tensions to be applied accurately in cold work situations, where hydraulics and other powered equipment cannot be used. Referring now to Figs 6 to 20, a second embodiment of a fixing will now be described. The second embodiment differs from the first embodiment in respect of the number of wedges provided in the wedge device. Typically two or more than two wedges are provided. In the second embodiment, three separate pairs of wedges are provided, but more or less than three pairs can optionally be provided. Also, the wedges can be provided in some other arrangement different from the symmetric pairs as shown in the second embodiment.

Figures 6 to 17 show the fixing attached to a schematic member M forming part of a connection. As with previous embodiments, the second embodiment of the fixing can be used with various types of connection, and by way of one particular example (see Figs 18 and 19) the member M can comprise a part of a flanged connection between two pipes as described for the previous embodiment. However, the scope of the invention is not limited to fixings for use on such connections, and the member M is not to be construed as limiting for the purposes of this disclosure.

Referring now to Figs 6 to 20, the second embodiment of the fixing 115 typically has a fixing body 116 and a threaded shaft or stud 117. As best shown in Figures 17 and 18, the stud 117 typically passes across the connection, and is fastened at each side of the connection. Optionally the stud 117 can be provided with a fixing body 116 on each side of the connection, but it is sufficient for the threaded stud to be secured against axial movement on a single side of the connection (for example with a simple nut), and to be provided with a fixing body 116 on only one side of the connection as is shown in Figs 18 and 19. Optionally, the fixing body 116 can incorporate a spacer plate (s) located between the wedges and the flange or other article forming part of the connection.

Fixing body 116 includes a head plate H having an axial aperture therethrough to accept the stud 117, which terminates with a hex- head but which could be a plain stud provided with a nut. The head plate H has upper and lower tapered faces on its inner surface which meet at an apex that is aligned with the axis of the stud 117, so that the upper and lower tapered faces of the head plate H are symmetrical around the axis of the stud 117. The angle of the tapered faces on the head plate H is typically 6 degrees.

The fixing body 116 includes a wedge device comprising three pairs of wedges 140. Each pair of wedges 140 is arranged symmetrically above and below the axis of the stud 117, and the wedges in each pair are interconnected by bolts 123. Typically, each pair of wedges 140 has a respective pair of bolts 123 spaced laterally on either side of the axis of the stud 117, as best shown in Fig 7. Typically the upper wedges having plain apertures to allow the passage of the bolts, and the lower wedges have threaded apertures to engage the bolts, but this arrangement could be reversed. Typically the apertures and faces of the wedges are greased before assembly.

Each wedge 140 has an outer face and an inner face. The outer face faces the head plate H, and the inner face faces the spacer S, or the connection, e.g. the flanges F in this case. Typically the inner and outer faces of each wedge are not set at the same angle, although this is possible in certain embodiments. Typically the outer face of each wedge is set at a more acute angle than the inner face. Typically, the outer faces of the first pair of wedges 140a engage the tapered faces of the head plate H. Typically the outer face of the second pair of wedges 140b engage the inner faces of the first pair of wedges 140a. Typically the outer faces of the third pair of wedges 140c engage the inner face of the second pair of wedges 140b. Typically the inner faces of the third pair of wedges 140c engage the spacer, and are typically perpendicular. Thus, each face of each wedge slides relative to a parallel face on an adjacent wedge, or on a spacer S or on the head plate H, so that radial movement of each wedge 140 relative to the axis of the stud 117 leads to sliding of the respective opposing faces of each of the wedges 140, typically supporting the inter-engaged faces at the same angle during the radial movement.

Typically the outer faces of the first pair of wedges are set at the same angle as the inner face of the head plate H, i.e. 6 degrees. Typically the outer faces of the second pair of wedges 140b, and the inner face of the first wedge 140a, which engage in the assembled fixing body 116 are set at the same angle, which is 3 degrees. Typically the outer faces of the third pair of wedges 140c, and the inner faces of the second pair of wedges 140b are set at the same angle, which is typically 0.25 degrees.

In operation, the fixing 115 is applied to a connection as shown in Fig 18, with each pair of wedges 140 being radially separated as shown in the inactive configuration of Fig 18, where substantially no axial tension is being applied to the stud 117. Typically the fixing body 116 is applied to only one end of the stud 117 on one side of the connection, but optionally, a fixing body 116 can be applied to each side. In the embodiment shown in Fig 18, only one fixing body 116 is applied to each stud 117 on one side of the connection, and the stud 117 typically has a plain nut located on the other side of the connection. Typically the stud 117 is passed through the aperture in the head plate H, and is threaded between the pairs of wedges 140, and the bolts 123, to pass through an aligned aperture in the hole in the spacer S, from which it passes through the connection, and the stud 117 is then torqued up in known fashion to an initial tension. When the stud 117 is to be torqued up to a high tension for setting the connection, the stud 117 is tightened to its initial capacity, for example by means of a torque wrench, but in certain embodiments of the invention, it is perfectly acceptable to tension the head of the stud 117 to finger tightness and to rely on the wedges 140 for substantially all of the tensioning force to be applied to the fixing 115. When the stud 117 is tensioned to the appropriate tension to hold all of the components together with the inner and outer faces of the wedges being inter engaged with one another and with the spacer S and the head plate H, the operator first of all tightens the bolts 123a passing through the first pair of wedges 140a as shown in Fig 8. As the first bolts 123a are tightened, the two first wedges 140a approach one another radially from either side of the axis of the stud 117. The lower of the pair of wedges 140a typically has a thread cut in the aperture that receives the bolt 123a, so that rotation of the bolt 123a relative to the lower wedge in each pair draws the two wedges 140 together. The radial movement of the first pair of wedges 140a pulls the pair of wedges 140a radially together, but also forces them to slide axially inwards towards the spacer S. The axial component of movement of each pair of wedges is governed by the slope of the inner face of the component on which they slide. In this case, the first pair of wedges 140a slide on the tapered inner faces of the head plate H, and the axial displacement resulting from the radial movement of the wedges is governed by the starting position of the wedges on the tapered face, and their finishing position, typically at the apex of the inner face of the head plate H. The axial movement of the wedges as they slide down the tapered face of the adjacent outer surface applied an initial tension to the fixing 115 dependent on the extent of axial movement. Typically, the movement of the first pair of wedges 140 has a relatively long axial component, and applies a relatively large tensioning force to the stud 117, but typically has a relatively low level of accuracy as a result, and typically requires a high torque to be applied. Therefore, driving the first wedge 140a to the limit of the bolts 123a typically only tensions the stud 117 to a moderate tension. The first pair of wedges 140a is therefore used to apply the initial tension to the stud 117 before applying higher tensions using the second and third pairs of wedges 140b, 140c. When the first pair of wedges 140a has been tensioned as shown in Figs 8 and 9, the second pair of wedges 140b is then tensioned in a similar manner, leading to the configuration shown in the Figs 10 and 11.

The radial component of the movement of the second pair of wedges 140b is typically substantially the same as the radial component of movement of the first wedge 140a, but because the angle of the inner face of the first wedge is steeper (closer to perpendicular) than the angle of the head plate H, the axial component of movement arising from the radial displacement of the second pair of wedges 140 is typically less than that of the first pair of wedges 140a. Therefore, the radial movement of the second pair of wedges 140b typically increases the tension in the stud 117 by a relatively smaller amount than the radial movement of the first pair of wedges 140a; however, for a given value of torque applied to the bolts 123, the second pair of wedges 140b can increase the tension in the stud 117 more than the first pair of wedges. The differential slope provides a gearing effect so that the radial movement of the second wedge 140b permits the second wedge 140b to be tensioned to the limit of the bolts 123b (which may be at the fully engaged position shown in Fig 10 and 11 or may be reached when the wedges 140b are spaced radially apart from one another. This induces higher levels of tension in the stud 117 while applying the same values of torque to the bolts 123b that was applied to the bolts 123a.

When the first wedges 140a are radially driven to the torque limit of the bolts 123a, the effective torque limit of the bolts 123a could be reached before the pair of first wedges 140a meet together at the axis of the stud 117. Also, the limit could be reached before the stud 117 acquires the desired amount of tension. However, because of the gearing effect arising from the differential slopes supporting the first and second pairs of wedges, it is still possible to apply torque to the second bolts 123b to apply additional tension to the stud 117 which goes beyond the torque limit of the first bolts 123a driving the first wedges 140a. Typically the second bolts 123b are then tensioned up to their torque limit, which typically (but not necessarily) involves the meeting of the opposing faces of the pair of second wedges 140b as shown in Fig 10, at which point the third wedges 140c can be tensioned in the same way.

In a similar manner, third wedges 140c slide on the inner surface of the second wedges at an even steeper (closer to perpendicular) angle, and therefore the axial component of movement of the third wedges 140c resulting from the radial displacement of the same is even smaller, and hence the gearing effect is even lower, allowing additional tension to be applied to the stud 117 for the same force that is applied to the bolts 123 to tension them to their limit. Accordingly, once the second bolts 123b have been tensioned to their maximum torque limit, the third bolts 123c can be tensioned to their maximum torque levels to induce even higher tension in the threaded stud 117, which would be impossible to achieve without the gearing effect provided by the differential slopes.

The inter-engaging faces of the wedges can be graduated in successively smaller angles with respect to the perpendicular end face, so as to provide as many sets of "gears" as are desired. It should be noted that the angles shown in the figures of the second embodiment attached are schematic and are exaggerated in order to best describe the invention, and that it is possible to obtain the sequential gearing effect described above with extremely small variations in the angles between the inter engaging faces of the wedges. For example, a typical sequence of angles for inter engaging faces of successive wedges could be as follows (with respect to a perpendicular end face of the member M) 7°, 6°, 5°, 4°, 3°, 2°, 1°. Alternatively, larger increments between adjacent wedges can be provided for larger axial movements with lower sensitivity and lower accuracy, for example 30°, 25°, 20°, 15°, 10°, etc. The differential sloping faces of the wedges also permits finer tuning of the tension at the higher tension levels reached when the second and third wedge pairs are being tensioned. This allows more accuracy in applying the correct level of tension in the stud 117.

It should be noted that in the schematic views of the embodiments shown the upper and lower wedges meet at the axis of the stud when the final tension is reached, but in practice this is not necessary. Typically the first wedges 140a may reach that configuration, but at least the second and third pairs 140b, c will reach the torque limit of their bolts 123 before the top and bottom wedges meet at the axis. Also, the schematic drawings show the top and bottom wedges in each pair moving to the same extents during the tensioning process, but this is also un-necessary in practice, and the top and bottom wedges may reach their limit of travel at the torque limit of the bolts before they reach symmetrical positions above and below the axis of the stud 117.

Referring now to Figs 21 and 22, a third embodiment is shown, similar to the second, but differing in that the outer surface of the spacer plate is set at an angle (typically of 0.25 degrees) rather than being perpendicular as in the second embodiment. Hence, the final pair of wedges 223c has the general form of a truncated isosceles triangle rather than a right triangle, and has more resistance to locking up than the second embodiment, and better axial force transduction for a given amount of radial movement. Otherwise, the components of the third embodiment are the same as the second, with similar numbering with the values increased by 100. Hence, the wedges 240, stud 217, head plate H, bolts 223 and spacer S all function as previously described for the second embodiment. A fourth embodiment is shown in Figs 23 and 24, having a stud 117, a head plate H, a spacer S' with an angled outer face, bolts 323 and a single pair of wedges 340, which function as described in earlier embodiments. The difference from previous embodiments is 1) the number of bolts per wedge; and 2) the number of wedges provided. In the Fig 23 embodiment the wedge device has numerous bolts passing through a single pair of wedges above and below the stud axis. Each wedge has up to 6 bolts passing through it, and so the tensioning force applied by the bolts to drive the wedges can be spread through the numerous bolts 323. More or less than 6 bolts can be provided per wedge of course, and the concept of more than two bolts per wedge can be applied to the previous embodiments incorporating different numbers of wedges. More than one pair of wedges can be provided in this embodiment also. The inner and outer wedge angles can be as described for previous embodiments.

Figs 25 and 26 show a fifth alternative embodiment, in which the wedges 440 are typically as previously described, as are the bolts 423, member M, head plate H and stud 117. The difference in the Fig 25 embodiment resides in the spacers, which in the present case are interspersed between the wedges. In the present embodiment, the spacers comprise an angled spacer SI at the outer face of the member M, a similar spacer SI facing it, and between the two a modified spacer Sla having shallow convergent angled surfaces. The inner and outer surfaces of the spacers SI and Sla are typically set at the same angle as the angle of the wedges 440c and 440d on the inner part of the fixing, e.g. 2 degrees. Optionally the wedges 440c and 440d could be set with different angles from one another, and would be typically bounded by spacers with the same opposing angle. The outermost wedges 440a and 440b are similar, and are bounded by spacers s2 and S2a as shown in Fig 25 and 26, but have larger angles, e.g. 6 degrees. Again the outer wedges 440a and b could be set at different angles to one another, like the Fig 6 embodiment. The wedges 440 are sequentially driven together as previously described for earlier embodiments, starting with the outer wedges 440a and b, which because of their larger angles cause more axial displacement and higher tensioning than the inner wedges 440c and d, but the inner wedges 440c and d can, as a result of their smaller angles, reach higher tension in the stud 117 as a result of their lower gearing effect, as previously described for other embodiments. The wedges are typically tensioned in the sequence, a, b, c, and d, with each wedge having the same or a smaller face angle as the previous wedge.

The sixth embodiment shown in Figs 27-31 has a single pair of wedges 540 arranged above and below the axis of the stud 117, which are fastened together by adjuster bolts 523 (e.g. by one, two or more bolts 523). The wedges 540 are typically formed as right triangles which are symmetrically opposed to one another. Optionally the bolts 523 extend through radial apertures 541 in the wedges which are formed as slots so that the upper wedge 540 can translate axially relative to the bolts 523 when the bolts are tensioned, as shown when comparing Figs 27 with 29. Tensioning the bolts drives the upper wedge down the slope of the lower wedge and results in axial expansion of the wedge device which increases the tension of the stud 117.

Modifications and improvements can be incorporated. Typically, the components of the present apparatus and formed from corrosion resistant materials, such as high tensile steel, typically alloyed with certain anti-corrosion elements. The angle of the sloping faces can be changed to apply different mechanical advantages in different fixings 15. Optionally the angles on each of the fixing bodies 16a and 16b typically are the same, but this is not necessary. In certain embodiments of the invention, the fixing can be tensioned using lower forces acting on the fixing than would be needed to tension the stop member on the shaft, as the mechanical advantage provided by the wedge device can allow a lower force to be applied to the fixing for a given final tension in the shaft. Also, it can be an advantage that the orientation of the axis of movement of the wedge can be varied, as this allows smaller tensioning tools such as spanners etc. to be used in different orientations that might be more usable in inaccessible locations, where it is not feasible to turn the stop member provided by the nut with a larger spanner, possibly requiring rotation in a different plane, typically around the axis of the shaft. In certain embodiments, it can also be an advantage that application of the fixing does not require any rotation of the stop member in the final tensioning step, as the final expansion of the fixing body when the wedge slides against the collar is an axial and radial movement not dependent on the rotation of the nut under load. Hence the nut can remain stationary during the final tensioning step. Accordingly, large stop members such as high diameter nuts can be moved into the required axial position on the shaft when not under load, without the requirement to overcome the higher frictional forces that would resist turning of the large diameter nut in the final tensioning step. Instead, the final tensioning step is typically carried out by driving a smaller diameter nut on the adjuster, to drive the wedge.

Embodiments of the invention allow remedial actions to replace worn, damaged or corroded bolts, but embodiments of the fixing of the invention can be used in new constructions.

Embodiments of the invention allow mechanical advantage in applying force to the fixing, as the angle of the wedge can be varied to suit the circumstances. For example, when high forces are required to apply a fixing, the wedge angle can be reduced, so that a small amount of force applied to the wedge to drive it radially inwards towards the axis of the connection results in a larger force applied to the shaft of the stud to close the connection.