GB2469933A

GB2469933A - Ratchet nut and pipe flange closing assembly

Info

Publication number: GB2469933A
Application number: GB1007206A
Authority: GB
Inventors: Jonathan David Morgan
Original assignee: Equalizer International Ltd
Current assignee: Equalizer International Ltd
Priority date: 2009-05-01
Filing date: 2010-04-30
Publication date: 2010-11-03
Also published as: GB201007206D0; GB0907460D0

Abstract

The ratchet nut 114, particularly useful for assisting closing a gap between pipe flanges, includes a body 140 and a gripping mechanism 160 to engage with a support member e.g. a threaded rod, to selectively prevent and allow axial movement of the nut relative to the support member depending on the direction of force applied to the nut. The mechanism includes at least one gripping portion 160c. An expansion device 180 is adapted to be actuated to urge the gripping portion(s) clear of the outer surface of the support member. The gripping portion may have an inner thread, which engages the thread on the support member, having a steeper angle with respect to the axis than a load-bearing face of an outer thread of the gripping portion. Alternatively the inner and outer threads may have a different geometry. A flange closing assembly and a method of closing a gap between opposed flanges of pipe sections includes aligning the opposed flanges, coupling them with a support member, locating a ratchet nut on the support member and operating an actuator to engage with a surface of one of the flanges and a surface of the nut.

Description

NUT

The present invention relates to a nut. In particular, but not exclusively, the invention relates to a ratchet nut for assisting with closing a gap between pipe section end flanges.

Various tools exist for facilitating handling of heavy loads in industrial operations where purely manual handling of components may not be convenient or even possible. In particular, it is desirable in many applications to generate high linear forces to push components into position, and various tools have been devised to address this aim.

This is exemplified in the pipeline construction industry. Pipelines are typically constructed from a series of pipe sections which are connected successively to each other at their ends. The ends of the pipe sections are provided with outwardly protruding flanges having mating faces designed to oppose and abut against each other at the opposing ends of adjacent pipe sections. Bolt holes are typically provided through the flanges allowing bolts to be inserted to join the adjacent flanges and pipe sections.

In order to join the sections, the pipe section ends need to be accurately aligned and manipulated to close a gap between the flange end faces. It is important also to align the flanges evenly to minimise differential strains across the opposed flange faces.

One known technique for joining of pipe sections may involve simply threading bolts into mating nuts seated in the opposing flange, and turning the bolts in the different bolt holes to progressively draw the flanges and pipe sections closer together. In some cases, joining of pipe sections may be facilitated by applying a hydraulic arrangement to draw the flanges together.

According to a first aspect of the invention therefore, there is provided a ratchet nut comprising: -a main body defining an axial bore for receiving a support member therethough; -a gripping mechanism for holding the nut in engagement with the support member to prevent movement of the nut relative to the support member in a first axial direction, the gripping mechanism including at least one gripping portion adapted to be movable with respect to the bore for selectively engaging the outer surface of the support member; and -an expansion device adapted to be actuated to urge the gripping portion clear of the outer surface of the support member.

In some embodiments more than one gripping portion is provided, e.g. two or more gripping portions. 3, 45 or some higher number (e.g. 6-10) gripping portions can be provided and can optionally be circumferentially spaced around the bore.

In some embodiments the expansion device can be located radially inwards of the gripping portion. In some embodiments with two or more gripping portions, the expansion device can be disposed between gripping portions, e.g. located radially and/or circumferentially between two gripping portions.

In this way, the expansion device keeps the gripping portion(s) out of the way for releasing the gripping mechanism and removing the nut from the support member (for example a rod) along the first axial direction.

The expansion device may be adapted to contact and/or engage an inner surface of the gripping mechanism. More specifically, the expansion device may be adapted to engage an inner surface of the gripping portion(s) to push the gripping portions outwardly, away from the support member.

The expansion device is typically a mechanical device, but in other embodiments could be an electrical or hydraulically actuated device.

The expansion device may be mounted for movement parallel to a main axis defined by the bore. The movement of the expansion device can be constrained. Further, the expansion device may comprise a sloped or inclined outer surface adapted to engage with an inner surface of the gripping portion(s) such that movement of the expansion device (e.g. sliding movement of the expansion device relative to the gripping portion(s)) in a direction that is parallel to the main axis pushes the inner surface of the gripping portions up, across and/or along the inclined surface to urge the gripping portions outwardly, and clear of the support rnerriber, i.e, to a position in which the gripping portion(s) is radially displaced with respect to the bore. The expansion device may be tapered, and for example, may take the form of a wedge, conical member and/or other tapered member.

The ratchet nut may include an actuating mechanism adapted to engage the expansion device to urge the gripping portions clear of the outer surface of the support member. The actuating mechanism may comprise a sleeve slidably coupled to, attached and/or connected to the main body for relative axial movement of the sleeve with respect to the main body.

The actuating mechanism may be coupled to, attached and/or connected to the expansion device. Thus, in an embodiment of the invention, the sleeve can be slid relative to the main body, thereby causing the expansion device to be moved axially, in turn urging the gripping portion(s) outwardly and clear of the support member so that the nut can be released by sliding the nut in the first axial direction.

The actuating mechanism and/or expansion device may be biased toward a default configuration, in which the gripping mechanism engages securely with the support member under load imparted to the nut in a first axial direction. In the default configuration, the nut may be moved readily along the support member in a second axial direction opposing the first axial direction to a desired position. The nut may therefore include a biasing device, for example a spring, for biasing the expansion device toward the default configuration.

Further, the gripping portion( 5) may be adapted to be urged into engagement with the support member under load applied via the nut along the first axial direction.

More specifically, the expansion device may be mounted to a frame slidably coupled to the main body.

The main body may have a recess formed in an inner wall of the main body, the recess being adapted to receive the gripping portions when urged and/or moved clear of the support member.

In embodiments of the invention, the expansion device may be mounted within the main body, and may be mounted between the main body and the support member.

In some embodiments, the gripping mechanism may comprise a collet for gripping the support member, and, in such embodiments, the gripping portions may take the form of collet segments located and/or spaced circumferentially around the support member.

The support member may take the form of a rod, wire or other similar elongate member. The support member may include a thread. Typically, the support member includes a buttress thread with an asymmetric tooth profile. The thread may have an engaging surface across which a load applied along the first axial direction is supported for holding the nut secure against movement in the first axial direction. The gripping portion(s) may comprise an engaging surface adapted to contact the engaging surface of the thread. The engaging surface on the internal thread of the gripping portion(s) can oppose the first axial direction, and can optionally be a steep angle, e.g. close to perpendicular to the axis of the bore.

The thread may have a second ratchet surface across which the nut can be slid along and with respect to the support member in a second axial direction opposing the first axial direction for locating the nut in a desired position on the support member.

According to a second aspect of the invention, there is provided a ratchet nut comprising: -a main body having an axial bore for receiving a threaded support member therethrough, the bore defining a main axis; -a gripping mechanism adapted to hold the nut in engagement with said support member; -the gripping mechanism comprising an inner thread having a load-bearing face adapted to engage with the support member and an outer thread having a load-bearing face adapted to engage with the main body; wherein the load-bearing face of the inner thread has a steeper angle with respect to the main axis than the load-bearing face of the outer thread so that load imparted to the nut along the first axial direction urges the respective load-bearing faces into engagement with the main body and the support member for preventing movement of the nut relative to the support member along a first axial direction.

The load-bearing faces may be arranged to face toward the first axial direction along which load is imparted to the nut for engagement of the gripping mechanism with the support member. More specifically, the load-bearing faces may define substantially perpendicular axes extending away from the faces with a component along a second axial direction opposing the first axial direction. The substantially perpendicular axes can be arranged at, for example, 0 to 45 degrees with respect to the axis of the support member.

The load-bearing face of the outer thread may be adapted to engage with an engaging surface of the main body. The engaging surface may be an inner surface of the main body. The main body may be provided with an internal thread, and the engaging surface may be a face of the internal thread.

The load-bearing face of the gripping mechanism may juxtapose, contact, locate against, abut and/or be oriented parallel to the engaging surface of the main body to be moved across the engaging face of the main body upon loading of the nut along a second axial direction opposing the first axial direction.

The outer thread may be in screwable engagement with the thread of the main body for facilitating removal of the gripping mechanism from the main body by unscrewing the gripping mechanism, typically without radial movement of the gripping mechanism relative to the support member.

Typically, the load-bearing face of the inner thread is adapted to engage with a buttress thread of the support member. The buttress thread may comprise a load-bearing face and a passive face, and the load-bearing face of the inner thread may be adapted to contact, locate against, abut and/or be oriented parallel to a load-bearing face of the buttress thread.

In this way, the inner thread may engage with the load-bearing face of the buttress thread to withstand a load applied to the nut along the first axial direction, the load being transmitted via the load-bearing faces, so that movement of the nut relative to the support member along the first axial direction is prevented. The passive face may be a non-engaging face.

The inner thread may include a ratcheting face adapted to abut, juxtapose, locate against and/or be oriented substantially parallel to the passive face of the buttress thread so that the ratcheting face moves across the passive face of the buttress thread when a load is applied to the nut along the second axial direction.

The load-bearing face of the inner thread typically has a steeper angle to the main axis than the load-bearing face of the outer thread by an angle of between 0 to 90 degrees. This assists to prevent lockout of the nut under load imparted to the nut in the first axial direction, allowing the nut to be readily removed, for example, via a release mechanism which may disengage the gripping mechanism from the support member, or by unscrewing the nut from the support member via the inner thread.

The gripping mechanism may be located between the axial bore and the main body, and/or may comprise at least one (optionally two or more) gripping portion.

The ratcheting face and/or passive face of the buttress thread is typically inclined to the main axis for deflecting the gripping mechanism radially outwardly. More specifically, the inclined ratcheting face and passive face may engage to allow the ratcheting face to be moved across the passive face of the buttress thread and along the buttress thread in the second axial direction upon imparting a load to the nut along the second radial direction.

The ratcheting face may be moved clear of an abutting passive face of the buttress thread by imparting a load to the nut along the second axial direction. The buttress thread may be formed from successive circumferential thread portions, and the ratcheting face may be adapted to be moved clear of successive threaded portions by imparting a load to the nut along the second axial direction. In this way, the nut can be "ratcheted" into position on the rod by manually pushing the nut along the support member in the second axial direction.

The inner thread and the thread of the support member may be in screwable engagement for removal of the nut from the rod along the first axial direction by rotating the nut about the rod, thereby unscrewing the nutfromtherod.

Alternatively or in addition, the nut may include a release mechanism adapted to disengage the gripping mechanism from the support member for removal of the nut from the rod along the first axial direction, for example, by sliding the nut axially in the first axial direction. In one embodiment, the release mechanism may comprise a sleeve coupled to an expansion device, wherein the sleeve is operable to actuate the expansion device to urge the gripping mechanism radially outwardly and clear of the threaded support member. Use of the release mechanism is a fast and efficient way of removal avoiding repeated turns of the nut. The technique of unscrewing the nut however has benefits as a fail safe.

The outer thread may be arranged with respect to the main body to permit the load-bearing face of the outer thread to be moved across the engaging face of the main body from an initial position to a second position in which the gripping mechanism is radially displaced from the initial position and/or in which the inner thread of the gripping mechanism is moved clear of the threaded support member.

In this aspect, the nut may include other features as defined with reference to the first aspect of the invention.

According to a third aspect of the invention there is provided a ratchet nut comprising: -a main body having an axial bore for receiving a threaded support member therethrough, the bore defining a main axis; -a gripping mechanism adapted to hold the nut in engagement with said support member; -the gripping mechanism comprising an inner thread having a load-bearing face adapted to engage with the support member and an outer thread having a load-bearing face adapted to engage with the main body; wherein a geometry of the outer thread is different from a geometry of the inner thread so that axial load in one direction permits radial displacement of the gripping mechanism to permit axial translocation of the nut with respect to the threaded support member, and axial load in another opposite direction restricts radial displacement of the gripping mechanism to resist axial translocation in opposite direction.

The load-bearing face of the inner thread may have a different angle with respect to the main axis than the load-bearing face of the outer thread so that load imparted to the nut along a first axial direction urges the respective load-bearing faces into engagement with the main body and the support member for preventing movement of the nut relative to the support member along the first axial direction. The load-bearing face of the inner thread may have a steeper angle with respect to the main axis than the load-bearing face of the outer thread.

The nut may include further features as defined with reference to the first and/or second aspects of the invention.

According to a fourth aspect of the invention there is provided a ratchet nut assembly, the assembly comprising a support member; and a ratchet nut having a main body through which the support member is received on a main axis, wherein the ratchet nut includes a gripping rriechanism selectively engaged with an outer surface of the support member to resist movement of the nut relative to the support member in a first axial direction.

The ratchet nut may be a ratchet nut as defined above with reference to any one of the first, second and/or third aspects of the invention.

According to a fifth aspect of the invention, there is provided a flange closing assembly, the assembly comprising: -opposed pipe flanges arranged to be joined; -a support member coupling the opposed pipe flanges; -a ratchet nut comprising a gripping mechanism holding the nut in engagement with an outer surface of the support member, the support member being received through a main body of the nut defining a main axis; and -an actuator for imparting a closing force to at least one of the opposed flanges, the actuator being supported at one end by the ratchet nut; wherein the ratchet nut resists movement along a first axial direction upon load being imparted to the nut by the actuator for closing the flanges.

The actuator may be a hydraulic actuator. The hydraulic actuator may typically include a dual or a single piston actuation mechanism. The hydraulic actuator may comprise a bore through which the support member is received. The support member may extend through aligned bolt holes in the opposed flanges. Thus, the support member may co-locate one or more of the flanges, the ratchet nut and the actuator along the length of the support member.

The first ratchet nut may be located near a first end of the assembly, and the actuator may be located between the first ratchet nut and an engaging face of one of the flanges. The assembly may include a second ratchet nut located near a second end of the assembly. The second ratchet nut may be adapted to engage an engaging face of the opposing flange. The ratchet nut may be a ratchet nut as defined above with reference to any one of the first, second and/or third aspects of the invention.

According to a sixth aspect of the invention, there is provided a method of closing a gap between opposed flanges of adjacent pipe sections, the method comprising the steps of: (a) aligning opposing flanges of adjacent pipe sections; (b) coupling the aligned flanges via a support member; (c) locating a ratchet nut on the support member; (d) locating an actuator against the ratchet nut; and (e) operating the actuator to engage with a surface of one of the pipe flanges and a surface of the ratchet nut, the ratchet nut being subjected to a load imparted to the nut by the actuator and resisting movement of the nut with respect to the support member along a first axial direction for moving the flange with respect to the rod.

The method may include the further step of releasing the nut by actuating an expansion device typically located radially inward of at least one gripping portion of the nut in engagement with the support member, and urging the gripping portion clear of the support member. Optionally the expansion device can be located between two gripping portions. The step of releasing the nut by actuating an expansion device may include pulling the nut from the support member in the first axial direction. Alternatively or in addition, the method may include the step of releasing the nut by unscrewing the nut from a threaded support member.

The method may include the further step of sliding the ratchet nut to a desired position along the rod, in a second axial direction opposing the first axial direction.

Other method steps may be defined with reference to corresponding technical features of the ratchet nut as defined with reference to any one of the first, second and/or third aspects of the invention, and/or the assemblies of the fourth and/or fifth aspects of the invention.

There will now be described, by way of example only, embodiments of the invention with reference to the following drawings, of which: Figure 1 is a perspective line representation of a closing assembly in accordance with an embodiment of the invention; Figures 2A to 2G are perspective line representations of a pipe flange closing system using the closing assembly of Figure 1 and showing sequential steps from set-up toward closure of end flanges of pipe sections to be joined, according to an embodiment of the invention; Figures 3 to 7 are line drawings of the ratchet nut according to an embodiment of the invention at successive stages of assembly from a disassembled configuration in Figure 3 to a fully assembled configuration in Figure 7; Figure 8 is an internal side view of the ratchet nut of Figures 3 to 7 under load applied to the nut in a first axial direction; Figure 9 is an internal side view of the ratchet nut of Figures 3 to 7 under load applied to the nut in a second axial direction; Figure 10 is an internal side view of the ratchet nut of Figures 3 to 7 configured for release; and Figure 11 is a perspective line representation of a closing assembly in accordance with a further embodiment of the invention.

With reference firstly to Figure 1, there is shown generally a flange closing assembly 10 for closing adjacent flanges of pipeline sections to be joined.

The assembly 10 includes a hydraulic actuator 12 and ratchet nuts 14,15 fitted to a pull rod 16 (the pull rod 16 constituting a "support member").

The hydraulic actuator 12 typically has dual cylinders 12a connected to a common drive member 12b, and the cylinders 12a are operable under hydraulic fluid control to move within the housings 1 2c and move the drive member 12b along and relative to the pull rod in the direction indicated by arrows 12d. By moving the drive member against a pipe flange, using the ratchet nut as a leverage platform, the flange can in turn be moved into alignment with a joining flange of a separate pipe section, as described in more detail below.

In order to provide support for the hydraulic actuator, the ratchet nut 14 is attached to the pull rod 16, and is located against a common end member 1 2e of the actuator which is attached to the piston housings 1 2c of the actuator 12. The ratchet nut 14 is attached such that it does not slip along the pull rod when a force is exerted on the nut in the direction indicated by arrow 14a (a "first axial direction"), for example, as may arise due to operation of the actuator. However, the nut 14a can be readily slid in the opposite direction (constituting a "second axial direction") along the rod for locating it in position closer to the actuator 12, thereby providing it with a ratchet effect. Thus, the ratchet nut 14 provides a platform for the actuator 12 to drive away from, and allows the actuator 12 to be readily positioned at a suitable axial location on the pull rod 16 as required.

The drive member 12b can move to exert a force against adjacent components (not shown) located on the rod 16 in the region 18. In the Figure 1 example, the assembly is designed for closing the gap between two pipe flanges in the region 18. The ratchet nut 15 is attached at a far end of the assembly in a corresponding manner to the nut 14 to withstand slippage and forces in the direction indicated by arrow 15a, helping to retain the flange in the region 18. The system for closure of the flanges is described in further detail below.

The actuator 12 is provided with holes 1 2h defining an inner bore so that it may be movably located on the rod 16. Similarly, the ratchet nuts 14,15 are provided with an internal bore. Thus, the rod 16 acts to co-locate the ratchet nuts, actuator and flanges (not shown) along the rod.

In another embodiment, such as that of Figure 11, an alternative assembly 400 uses a single piston hydraulic actuator 412 in a corresponding manner to that of the assembly of Figure 1.

In Figures 2A to 2G, a system for flange closing is depicted showing how the assembly described above can be applied to join two pipe flanges. In Figures 2A to 2B, two pipe sections 20,21 are brought together end on for joining together by virtue of bolt holes 22a, 23a provided through respective pipe flanges 22, 23 at the mating ends of the pipe sections.

Initially, the sections are positioned such that the flanges are spaced apart by around 1 m or less, and the pull rod 16 is located through the aligned bolt holes 22a and 23a in the two opposed flanges.

The hydraulic actuator 12 is slid over the pull rod 16 and is moved along it to a position where the drive member 1 2d abuts the rear face 22b of the flange 22. The pistons of the actuator are retracted, at least in part. The ratchet nuts 14 and 15 are then fitted to the pull rod as shown in Figure 2D. Two nuts are slid onto the rod in opposite orientations from opposing ends of the assembly. The ratchet nut 14 is located against the actuator 12 as described above to provide a platform against which the pistons can work against to move the drive member. The second ratchet nut 15 is manually pushed onto the pull rod 16 at the opposite end, into abutment with a rear face 23b of the flange 23. Figure 2D represents a starting configuration for drawing the flanges toward each other and closing the gap 26.

In order to close the gap, the hydraulic actuator is engaged and the drive member exerts a force against the rear face of the flange 22. The pistons extend from their housings progressively moving the flange 22 toward the flange 23, the flange being supported by the ratchet nut 14 locked against the pull rod giving a stable platform, and providing a reaction force.

When the pistons reach full stroke as shown in Figure 2E, they are disengaged, and are retracted back into their housings, before being pushed with the ratchet nut 14 along the pull rod 16 toward the flanges until the drive member is again brought into abutment with the rear flange face 22a ready for another drive cycle, in the configuration of Figure 2F.

The actuator is then engaged to push the flange 22 further toward the flange 23 of the second pipe section. In this way, the gap 26 is reduced progressively by repeatedly engaging the actuator and moving it along the pull rod as described above, until the gap has closed and the front faces 22c and 23c of the respective pipe flanges are located against each other with the bolt holes aligned. The ratchet nuts, actuator and pull rod are then removed, typically after bolts are inserted through adjacent bolt holes and tightened to secure the pipes together. The ratchet nuts are removed from the pull rod by virtue of a release mechanism that allows them to be drawn along the rod away from the join. Bolts can be tightened in adjacent holes between each cycle of the pistons, to maintain closure while pistons are retracted.

In other embodiments, two or more such closing assemblies could be applied to different bolt holes with the drive actuators synchronised. This can help to ensure alignment of the flanges while closing the gap.

In another embodiment, the assembly may be provided without a second ratchet nut 15, for example, in a vertical jacking application where the actuator piston acting from the ground against the ratchet nut, in turn secured to the rod, pushes a component upward. At the end of each lifting cycle, the piston is retracted downward, leaving the component resting on the rod end. The ratchet nut is then returned to locate against the piston before another piston drive cycle is commenced to lift the component further.

Turning now to Figures 3 to 7, a ratchet nut 114, similar to the nut 14 described above in relation to Figures 1 and 2, is now described in more detail below.

In Figure 3, the ratchet nut 114 is shown in a fully disassembled configuration revealing constituent parts, and Figures 4 to 7 show the ratchet nut 114 at successive stages of assembly.

The ratchet nut 114 in this example has three main parts, namely a cylindrical main body 140 providing rigid housing for different components, a gripping mechanism 160 which allows the nut to grip a pull rod (not shown), and a release sleeve 180 for selectively disengaging the gripping mechanism from the pull rod. These components of the nut are typically designed to align on a central axis 114a, and together define an internal bore 1 14b by which the nut can be located on a pull rod (not shown) for attachment.

The gripping mechanism 160 in this example includes at least one, typically two, and in this example, typically three collet segments 1 60c (constituting "gripping portions") each with an inner thread 1 60i which may grip securely to a corresponding thread on an outer surface of a pull rod (not shown) located through the bore 114b. These collet segments 160c are spaced around and rest against an inner supporting cage 162, as may be seen in Figures 3 and 4. In particular, inner surfaces 1 60e of the collet segments 1 60c rest against sloped surfaces 1 62f and 1 62r toward front and rear ends 1 60x, 160y of the cage 162.

In this configuration, the cage 162 can be moved axially with respect to the collet segments 1 60c so that the collet segments 1 60c are pushed along the sloped surfaces 1 62f, 1 62r to force the collet segments radially away from the axis of the bore 1 14b.

The release sleeve 180 is attached to the cage 162 and can be pulled to move the cage with respect to the collet segments 1 60c and urge them outwards and keep the collet segments away from the bore and disengaged from a rod which may be received in the bore.

In more detail, the nut 114 is assembled by mounting the collet segments to the cage 162. The segments 1 60c fit into circumferentially spaced apart longitudinal slots 162s in the cage 162. The inner threaded surface I 60i may protrude inwardly through the slot for engaging with a rod provided through the axial bore 114b. The segments are loosely seated in the slots so that the cage 162 can be slid with respect to the segments 1 60c in a direction along the slots 162s, and with inner surfaces 1 60e located against the sloped surfaces 1 62f, 1 62r. Tie rods 1 62t connecting ends of the cage 162 are located between the adjacent segments 160e. Further, conical portions 162c, 162d of the cage are located inside and between opposing collet segments 1 60e near the cage ends 1 62x, 1 62y.

The cage and the collet segments 160 fitted to the cage as indicated in Figure 4, are inserted and housed in the main body 140. To achieve this, the collet segments have provided on their outer surface an outer thread 1600 which is relatively coarse compared with the inner thread 160i, and is configured to engage with a mating thread 140m on an inner surface of the main body 140. This allows the collet segments 160c and cage 162 to be screwed into and be attached to the main body. The thread is typically continuous around the outer surface of the collect segments 1 60c when they are assembled correctly as shown in Fig 4.

When threaded into place in the main body the collet segments are a "rattle fit" in a radial direction, allowing a measure of radial movement for the collet segments within the main body. To prevent the segments from being displaced in a longitudinal or axial direction however, a locking ring 164 is fitted around a cylindrical end 162j of the cage and attached to the main body. The locking ring 164 has a notch 164n on a peripheral edge of the ring 164 that locates into a corresponding slot 140s in the main body to prevent rotation of the locking ring with respect to the main body about the main axis 114a. The locking ring locates against end surfaces 160j of the collet segments 160, on the front side of the locking ring. On the rear side, a lock ring retaining clip 166 is fitted into a circumferential groove 140g in an internal surface of the main body 140. The clip 166 protrudes inwardly when seated in the groove so that it overlaps a rear edge of the locking ring 164 keeping it attached to the main body.

In this manner, the locking ring and clip 166 are fixed to the main body, and the collet segments are kept in place between an inner surface of the main body and the bore 1 14b by virtue of the locking ring 164, the inner thread of the main body and the internal supporting cage 162. The cage 162 is slidable in an axial direction with respect to the main body 140 and collet segments 160 as indicated by arrow 168 in Figure 5.

To complete the nut assembly, the release sleeve 180 is attached, both to the cage 162 and to the locking ring 164, but such that the cage 162 can be moved axially with respect to the body by correspondingly moving the sleeve 180. For this, the sleeve 180 is aligned and placed around a rear end 140j of the main body, and the cage end 162j. Biasing pins 168 are located through circumferentially spaced apart bores 180b of the sleeve which extend longitudinally and align with bores 164b in the locking ring 164. The biasing pins 168 are each provided with a biasing compression spring 168s which abuts a pin head 1 68h and away from the head end have a threaded portion 168t. The threaded portion 168t engages with a thread 164t provided in bore 164b of the lock ring to securely fasten the pins to lock ring 164. Spring ends 168e abut against an annular step flange provided in the sleeve (described further below) protruding inwardly from the respective bores 1 80b of the sleeve. Thus, the biasing compression springs 168s act against the pin heads 1 68h fixed to the main body 140 and the step of the sleeve 180 and thereby tend to bias the sleeve toward the main body 140. By pulling the sleeve away from the main body with sufficient force to overcome the spring bias, the sleeve can be moved axially away from the main body by a distance determined, in this example, by the length of the biasing pins 168 and amount of compression accommodated by the springs 168s. The biasing pins also function to keep the sleeve in place with respect to the main body and add stability and robustness to the nut design.

With the sleeve attached to the main body as seen in Figure 6, the sleeve is attached to the cage 162. An adjusting ring 170 is located over the cage end 1 62j and against a face 1 80f of the sleeve. The ring 170 has a straight-edged portion 1 70s on an inner circumference of the ring that aligns with a cut-out 162u in the cage end 162j. A retaining clamp in the form of a circlip 172 is snapped into a circumferential groove in the cage end 162 and protrudes radially to overlap an inner edge of rear face 1 70r of the adjusting ring to keep it in engagement with the cage 162.

The adjusting ring 170 is secured also to the sleeve by screws 174 that sit against grooves 1 70g in an outer circumferential edge of the ring 170 and are screwed into threaded holes 1 80h of the sleeve. The adjusting ring straight-edge portion and cut-out 1 62u of the cage orients the adjusting ring 170 50 that the grooves 1 70g align correctly with the holes 1 80h in the sleeve for attachment of the screws. The screw heads 1 74h clamp against the outer edge of the ring 170. In this way, the sleeve is secured to the cage 162 so that moving the sleeve axially away from and with respect to the main body moves the cage correspondingly. Internally, the longitudinal movement of the sleeve toward the rear with respect to the main body causes the collet segments to move outwards radially, to disengage the collet segments and move them clear of the rod, allowing the nut to be released.

The engagement and release mechanism of the nut is described further below with reference to Figures 8 to 10. In these figures, the nut 114 described above is shown in use with a pull rod 200.

Figure 8 shows the nut 114 located in position and under a load applied to the nut along a first axial direction as indicated by arrows 300, parallel to the main axis 114a. Under these load conditions, mating thread 140m of the main body 140 by virtue of its geometry engages the coarse outer thread 1600 on the collet segments 160c and tends to urge these segments 1 60c radially inwardly toward the rod 200. In addition, the cage 162 is urged to a fully inserted position in the main body with the front conical portion 1 62d located against an inner front end surface 1 40f.

The load applied to the nut 114 is transmitted to the collet segments across an engaging face 140e of the thread 140m in contacting engagement with a load-bearing face 1601 of the outer threads 1600 of the collet segments. The load engaging faces 1 40e of the main body face inwardly to exert a force against the segments 160c so that the collet is pushed radially inward toward the rod 200. The inner thread 1 60i of the collet segments engages with a buttress thread 202, and load is further transmitted to the buttress thread across a second, inner load-bearing face 160k of the collet thread 1601 in contacting engagement with a load-bearing face 2021 of the buttress thread. The load-bearing face 1601 is oriented at a high angle to the main axis for facilitating its load-bearing capacity of the nut. With load applied in this way, the collet segments are forced to engage and grip buttress thread securely preventing movement in the direction of load 300. Due to the loading and geometry of sloping portion 1 62c in abutment with an inner engaging surface 1 60e, the cage and sleeve are prevented from readily being retracted with respect to the main body. Accordingly, the front end of the nut can be used to provide a solid and secure non-slip platform for, for example, supporting a flange closing or other jacking arrangement as described above with reference to Figures 1 and 2A to 2G.

When the nut is pushed along the rod in the direction opposite that indicated by arrows 300, i.e., the direction of load is reversed, the nut can be readily slid into a desired position along the rod. In this configuration as seen in Figure 9, the locking ring 164 abuts rear end surfaces 1 60r of the collet segments to restrain rearward movement of the collet segments in the space between the rod and the main body. Toward the front end of the nut, the collet segments are retained by the engaging faces 140e of the main body. The collets sit in the space between the rod and the main body as a "rattle fit" so that it can move radially, but the engaging surface 140e, which faces inward tends to urge the collet segments toward the rod. The sleeve 180 and cage 162 are biased by springs l68sto a fully inserted position in the main body 140 similar to the position taken up in Figure 9. However, when loaded in the direction of arrows 330, the collet segments are free to move readily across sloped passive faces 202p of the buttress thread. The inner thread 160i has a passive face 1 60p which contacts and rises up the sloped face 202p in one circumferential thread section 202n thereby moving the collet outwards until it reaches and passes the apex of that particular thread section 202n at which point it drops back inwardly following the buttress thread profile before again moving up the shallow sloped face 202p in the next section 202n in succession along the direction of load 330. As the nut is moved along the rod, the collets follow therefore the buttress thread profile, moving radially inward and outward within the main body between the main body and the rod, without significant axial resistance, until the desired position is reached. Thus, the nut has a ratchet function in that under load in one direction as seen in Figure 8, movement between the rod and the nut is prevented, whilst in the opposing direction of load as seen in Figure 9 movement is permitted, and the nut can be readily moved axially along the rod to a selected position.

As the buttress thread causes the collet segments to move outward and the engaging faces 140e tend to urge the collet segments inward, the position of the collet segments, although a rattle fit, is controlled. This eliminates the need to separately bias the collet segments against the rod, cage or other parts of the nut, offering improvements in simplicity and robustness of design.

With the load substantially removed as shown in Figure 10, the nut 114 is released and can be removed axially rearward from the rod as indicated by arrows 302. In this configuration shown in Figure 10, the sleeve 180 is retracted back from the main body 140 by a distance indicated by bars 304, compressing the springs 168s. The inner engaging surfaces 160e of the collet segments 1 60c move across and ride up along outer surfaces 162r,162f of the sloping portions 162c,162d so that the collet segments 1 60c are moved outwardly as indicated by arrows 306 and clear of the buttress thread 202. The sloping portions act as a wedge against the inner surfaces of the collet segments to force the segments outward.

Thus, longitudinal or axial movement of the sleeve and cage forces radial movement of the collet segments. Upon movement of the collet segment outward, the load-bearing surfaces 1601, 160k slide across the respective engaging surface 1 40e of the main body and load-bearing surface 2021 of the buttress thread. The outer thread 1600 of the collet segments occupies a space 140s between the threads 1600 and 140m. In this way, the collet segments are moved clear of the buttress thread.

By keeping the sleeve retracted, the collet segments are held in the disengaged position of Figure 10, and the nut can be readily slid off the rod by moving it along the rod in the direction of arrow 302.

In order to achieve an effective engagement and release, collet segments are designed so that the inner load-bearing face 160k has a steeper angle 308 to the main axis 11 4a than the angle 310 of the load-bearing face 1601 of the outer thread 1600. This arrangement helps collet segments to be forced against the buttress thread under load in the first axial direction 300. The angle of intersection 312 between face-parallel axes 314,316 of load-bearing faces of the inner and outer threads 1 60i, 1600 is between 0 and 90 degrees. Further, the angle 308 of the inner load-bearing face is typically an acute angle, between 0 and 90 degrees, to the main axis 114a. In this example, the angle 308 is between 75 and 85 degrees, e.g. degrees, and the angle 310 is between 30 and 70 degrees, e.g. 50 degrees. The angle 312 made between the intersection of the face-parallel axes has a typical value of around 30 degrees. This typical geometrical configuration assists release of the collet segments from the buttress thread as no displacement of the collet segments and main body is required against the load direction 300 to enable release. This is useful particularly where a front end 1 40a of the nut sits tightly against another component such as a pipe flange or hydraulic actuator which cannot readily be moved to provide space.

In this example, the profile of inner thread 1 60i complements that of the buttress thread, and is asymmetric axially with circumferential sections 202n having a low resistance, "ratcheting" surface 160p with significantly shallower slope (typically between 0 and 40 degrees) with respect to the main axis than that of the load-bearing face 160k (typically in the range of to 85 degrees). The outer thread 1600 is also provided with a passive back face 1 60b. In profile, the outer thread 1600 is also asymmetric in this example, with the load-bearing face 1601 having a slightly shallower angle (50 degrees in this example) with respect to the main axis than that of the back face 160b (70 degrees in this example).

The overall geometry of the collet segments and the space in which they are mounted in the recess of the main body is such that the collet segments are generally urged toward the bore; in hard engagement with rod to secure the nut under load in a first direction, and in sliding engagement with the rod when pushed in a second opposing direction for positioning the nut. Further, it provides for movement of the collets in a radial direction for sliding of the nut in second direction, and for axial release of the nut from the rod in the first direction.

The nut is provided with a back up release mechanism in that the threads of the collet segments together define a circumferential inner thread of the gripping mechanism 160 which allows the nut to be unscrewed from the rod. The angles of the thread faces facilitate release for unscrewing and moving the nut directly rearward, in the direction 302.

Embodiments of the present invention allow a number of advantages. In particular, the release mechanism and geometric configuration of the collet segments allows the nut to be removed more readily after use.

Components of the nut have multiple functions, which simplifies design and ease of use. For example, collets segments being held in a radial sense by the inner cage which also acts to release the nut, and the main body whilst containing the segments axially, also functions to bias the nut toward the bore and rod. The geometry of the nut facilitates withstanding high loads applied to the nut along one axial direction for leverage. The release mechanism allows the nut to be removed axially, without relying on unscrewing the nut.

Various modifications and changes may be made within the scope of the invention herein described. In particular embodiments, the buttress thread may have an alternative profile. For example, the buttress thread may have square profile, or could be a symmetrical variety. Similarly, the main body may be provided with a different thread profile in certain embodiments. In particular, it will be appreciated that alternative arrangements could be provided to move the collet segments outwards to disengage and release the nut from the rod. For example, a wedge could be provided in the spaces between the collet segments along the circumference of the nut. Different actuation devices are also envisaged in place of the sleeve. For example, an external lever could be used to actuate movement of the cage between the segments.

Claims

Claims: 1 A ratchet nut comprising: -a main body defining an axial bore for receiving a support member therethough; -a gripping mechanism for holding the nut in engagement with the support member to prevent movement of the nut relative to the support member in a first axial direction, the gripping mechanism including at least one gripping portion adapted to be movable with respect to the bore for selectively engaging the outer surface of the support member; and -an expansion device adapted to be actuated to urge the gripping portion clear of the outer surface of the support member.
2 A ratchet nut as claimed in claim 1, wherein the expansion device is configured to engage an inner surface of the gripping portion to push the gripping portion radially outwardly, away from the support member.
3 A ratchet nut as claimed in claim 1 or claim 2, wherein the expansion device comprises a tapered member.
4 A ratchet nut as claimed in claim 3, wherein the expansion device is movable parallel to a main axis defined by the bore, and the tapered member comprises a sloped or inclined outer surface adapted to engage with an inner surface of the gripping portion, such that axial movement of the expansion device urges the gripping portion radially outwardly to disengage the gripping portion from the support member.
A ratchet nut as claimed in any preceding claim, including an actuating mechanism adapted to engage the expansion device to urge the gripping portion into and/or out of engagement with the outer surface of the support member.
6 A ratchet nut as claimed in claim 5, wherein the actuating mechanism comprises a sleeve connected to the main body and movable relative to the main body.
7 A ratchet nut as claimed in claim 5 or claim 6, wherein the actuating mechanism is coupled to the expansion device to urge the gripping portion outwardly and clear of the support member.
8 A ratchet nut as claimed in any preceding claim, wherein in a default gripping position, the gripping mechanism engages with the support member under load imparted to the nut in the first axial direction.
9 A ratchet nut as claimed in claim 8, including a biasing device for biasing the expansion device toward the default configuration.
A ratchet nut as claimed in any preceding claim, wherein movement of the nut along the support member in a second axial direction opposing the first axial direction disengages the gripping mechanism from the support member allowing axial movement in the second axial direction.
11 A ratchet nut as claimed in any preceding claim, wherein the gripping portion is urged into engagement with the support member under load applied via the nut in the first axial direction.
12 A ratchet nut as claimed in any preceding claim, wherein the expansion device comprises a frame slidably coupled to the main body.
13 A ratchet nut as claimed in any preceding claim, having a recess in an inner wall of the main body, the recess being adapted to receive a part of the gripping portion when moved clear of the support member.
14 A ratchet nut as claimed in any preceding claim, wherein the expansion device is mounted within the main body between the main body and the support member.
A ratchet nut as claimed in any preceding claim, wherein the gripping portion comprises two or more segments that are spaced circumferentially around the support member.
16 A ratchet nut as claimed in any preceding claim wherein the gripping portion has an internal thread to cooperate with a threaded outer surface on the support member.
17 Aratchetnutas claimed in claim 16, wherein the internal thread has an asymmetric tooth profile.
18 A ratchet nut as claimed in claim 17, wherein the internal thread of the gripping portion has a first load-bearing surface opposing the first axial direction for resisting a load applied in the first axial direction.
19 A ratchet nut as claimed in claim 18, wherein the first load-bearing surface of the internal thread of the gripping portion is at a steep angle relative to the axis of the axial bore.
A ratchet nut as claimed in claim 18 or 19, wherein the thread has a second ratchet surface across which the nut can be slid along and with respect to the support member in a second axial direction opposing the first axial direction, and wherein the second ratchet surface is set at a shallower angle relative to the bore than the first load-bearing surface.
21 A ratchet nut comprising: -a main body having an axial bore for receiving a threaded support member therethrough, the bore defining a main axis; -a gripping mechanism adapted to hold the nut in engagement with said support member; -the gripping mechanism comprising an inner thread having a load-bearing face adapted to engage with the support member and an outer thread having a load-bearing face adapted to engage with the main body; wherein the load-bearing face of the inner thread has a steeper angle with respect to the main axis than the load-bearing face of the outer thread so that load imparted to the nut in the first axial direction urges the respective load-bearing faces into engagement with the main body and the support member for preventing movement of the nut relative to the support member in a first axial direction.
22 A ratchet nut as claimed in claim 21, wherein the load-bearing faces oppose the first axial direction.
23 A ratchet nut as claimed in claim 21 or 22, wherein the load-bearing faces define substantially perpendicular axes extending substantially perpendicularly away from the load bearing faces, wherein the axes have a component in a second axial direction opposing the first axial direction.
24 A ratchet nut as claimed in claim 23, wherein the substantially perpendicular axes extending from the load bearing faces are arranged at, an angle between 0 to 45 degrees with respect to the axis of the support member.
A ratchet nut as claimed in any one of claims 21-24, wherein the load-bearing face of the outer thread is adapted to engage with an engaging surface of the main body.
26 A ratchet nut as claimed in claim 25, wherein the outer thread of the gripping surface engages with an internal thread on the inner surface of the main body, and wherein the engaging surface comprises a face of the internal thread.
27 A ratchet nut as claimed in any one of claims 21-26, wherein the load-bearing face of the gripping mechanism abuts the engaging surface of the main body to be moved across the engaging surface of the main body upon loading of the nut in a second axial direction opposing the first axial direction.
28 A ratchet nut as claimed in any one of claims 21-27, wherein the outer thread is in threaded engagement with the thread of the main body for facilitating removal of the gripping mechanism from the main body by unscrewing the gripping mechanism, without radial movement of the gripping mechanism relative to the support member.
29 A ratchet nut as claimed in any one of claims 21-28, wherein the load-bearing face of the inner thread is adapted to cooperate with a thread of the support member.
A ratchet nut as claimed in any one of claims 21-29, wherein the inner thread has an asymmetric tooth profile, with a load bearing face and a ratcheting face having different angles with respect to the axis of the bore.
31 A ratchet nut as claimed in claim 30, wherein the load bearing face opposes the first axial direction, and has a steeper angle with respect to the bore than the ratcheting face, and wherein the ratcheting face is adapted to move across the thread of the support member for deflecting the gripping mechanism radially outwardly when a load is applied to the nut in a second axial direction opposite to the first axial direction.
32 A ratchet nut as claimed in any one of claims 21-31, wherein the angle of the load-bearing face of the inner thread relative to the main axis differs from the angle of the load-bearing face of the outer thread by an angle of between 0 to 90 degrees.
33 A ratchet nut as claimed in any one of claims 21-32, wherein the nut includes a release mechanism adapted to disengage the gripping mechanism from the support member for removal of the nut from the rod in the first axial direction.
34 A ratchet nut as claimed in claim 33, wherein the release mechanism comprises a sleeve coupled to an expansion device, wherein the sleeve is operable to actuate the expansion device to urge the gripping mechanism radially outwardly and clear of the threaded support member.
A ratchet nut as claimed in any one of claims 21-34, wherein the outer thread is arranged within a recess in the main body to permit the load-bearing face of the outer thread to be moved across the engaging face of the main body from an initial position to a second position in which the gripping mechanism is radially displaced from the initial position and/or in which the inner thread of the gripping mechanism is moved clear of the threaded support member.
36 A ratchet nut comprising: -a main body having an axial bore for receiving a threaded support member therethrough, the bore defining a main axis; -a gripping mechanism adapted to hold the nut in engagement with said support member; -the gripping mechanism comprising an inner thread having a load-bearing face adapted to engage with the support member and an outer thread having a load-bearing face adapted to engage with the main body; wherein a geometry of the outer thread is different from a geometry of the inner thread so that axial load in one direction permits radial displacement of the gripping mechanism to permit axial translocation of the nut with respect to the threaded support member, and axial load in another opposite direction restricts radial displacement of the gripping mechanism to resist axial translocation in opposite direction.
37 A ratchet nut as claimed in claim 36, wherein the load-bearing face of the inner thread has a different angle with respect to the main axis than the load-bearing face of the outer thread so that load imparted to the nut in a first axial direction urges the respective load-bearing faces into engagement with the main body and the support member for preventing movement of the nut relative to the support member in the first axial direction.
38 A ratchet nut as claimed in claim 36 or 37, wherein the load-bearing face of the inner thread has a steeper angle with respect to the main axis than the load-bearing face of the outer thread.
39 A ratchet nut assembly, the assembly comprising a support member; and a ratchet nut having a main body through which the support member is received on a main axis, wherein the ratchet nut includes a gripping mechanism selectively engaged with an outer surface of the support member to resist movement of the nut relative to the support member in a first axial direction.
A flange closing assembly, the assembly comprising: -opposed pipe flanges arranged to be joined; -a support member coupling the opposed pipe flanges; -a ratchet nut comprising a gripping mechanism holding the nut in engagement with an outer surface of the support member, the support member being received through a main body of the nut defining a main axis; and -an actuator for imparting a closing force to at least one of the opposed flanges, the actuator being supported at one end by the ratchet nut; wherein the ratchet nut resists movement in a first axial direction upon load being imparted to the nut by the actuator for closing the flanges.
41 An assembly as claimed in claim 40, wherein the first ratchet nut is located near a first end of the assembly, and the actuator is located between the first ratchet nut and an engaging face of one of the flanges.
42 An assembly as claimed in claim 40 or 41, wherein the assembly includes a second ratchet nut located near a second end of the assembly.
43 An assembly as claimed in claim 42, wherein the second ratchet nut is adapted to engage an engaging face of the opposing flange.
44 A method of closing a gap between opposed flanges of adjacent pipe sections, the method comprising the steps of: (a) aligning opposing flanges of adjacent pipe sections; (b) coupling the aligned flanges via a support member; (c) locating a ratchet nut on the support member; (d) locating an actuator against the ratchet nut; and (e) operating the actuator to engage with a surface of one of the pipe flanges and a surface of the ratchet nut, the ratchet nut being subjected to a load imparted to the nut by the actuator and resisting movement of the nut with respect to the support member in a first axial direction for moving the flange with respect to the rod.
A method as claimed in claim 44, wherein the method includes the further step of releasing the nut by actuating an expansion device located between two gripping portions of the nut in engagement with the support member, and urging the gripping portions clear of the support member.
46 A method as claimed in claim 44 or 45, including the further step of sliding the ratchet nut to a desired position along the rod, in a second axial direction opposing the first axial direction.