GB2487953A

GB2487953A - A pipe clamping apparatus

Info

Publication number: GB2487953A
Application number: GB201102361A
Authority: GB
Inventors: Robert Stephen
Original assignee: Equalizer International Ltd
Current assignee: Equalizer International Ltd
Priority date: 2011-02-10
Filing date: 2011-02-10
Publication date: 2012-08-15
Anticipated expiration: 2031-02-10
Also published as: GB201102361D0; GB2487953B

Abstract

A pipe clamping apparatus for supporting a clamped connection between two flanged pipes having an axis and flanges extending perpendicular to the axis. The clamping apparatus comprises at least two clamp devices fixed across the flanges, so that each clamp device engages a respective opposing face of the clamp connector, and having a force driver device to press the pair of clamp bodies together.

Description

APPARATUS AND METHOD

The present invention relates to apparatus and method for clamping a joint. In a particular embodiment of the invention, the joint is a flanged joint, and the apparatus and method of the invention relates to a clamp that is applied to the flanged joint.

Flanged connections are well known. Flanged connections are used to connect lengths of pipe. Typically a flange extends radially (i.e. perpendicularly away from axis of the pipe) at each end of each pipe section to be connected, so that the flanges on each end are parallel to one another. Typically, a resilient gasket seal is compressed between the opposing faces of the flanges, and can often be held in an annular groove in one or both of the faces of the flange.

Some flanges are bolted together by bolts passing axially (i.e. parallel to the axis of the pipe) through apertures in the flanges. In certain flange connectors, however, the flanges are not apertu red, and are clamped together rather than being bolted. In such cases, typically the flanged joint is secured by a clamp connector applying a clamping force to the flanges in a radial direction with respect to the axis of the pipe. A typical known clamp connector of this type is known in the art as a GRAyLOCtm connector, which clamps over mating flanges and holds them together.

Axial compression of the flanges by these clamp connectors is typically achieved by bolting the two parts of the clamp connector together, and drawing the upper and lower parts of the connector together in a radial plane, in line with the flanges, by tensioning the bolts which extend in a parallel plane to the flanges. The upper and lower parts of the clamp connector typically bear on the radially facing outer surfaces of the flanges and receive them in a common groove, so that as the pipe flanges move into the grooves on the clamp connector they are pressed together in an axial direction of the pipe to make up the seal.

This is a satisfactory method of connecting pipe ends, and many miles of pipelines and flow lines from many industries are connected in this manner. Pipelines and their connections are of course subject to degradation over time and flanged pipeline connections such as are described above typically suffer from bolt failure before the flanges and the gaskets reach the end of their usable lives. Therefore, remedial work on flanged pipeline connections frequently involves changing out corroded bolts that are connecting the two portions of the clamps.

According to the present invention there is provided a pipe clamping apparatus for supporting a clamped connection between two flanged pipes, the pipes having a central axis, and having flanges extending radially from the central axis, with a clamp connector fixed across the flanges by means of threaded fixings connecting two parts of the clamp connector wherein at least one of the two parts of the clamp connector moves radially with respect to the central axis of the pipe to clamp the flanges together, the clamping apparatus comprising: first and second clamp devices adapted to be applied to spaced portions of the clamp connector, each of the first and second clamp devices having a pair of clamp bodies adapted to engage opposing faces of the clamp connector, and a force driver device adapted to press the pair of clamp bodies together.

The invention also provides a method of supporting a clamp connector connecting two flanged pipes, the pipes having a central axis and having flanges extending radially from the central axis, with the clamp connector fixed across the flanges by means of threaded fixings connecting two parts of the clamp connector, the method comprising: applying first and second clamp devices around the clamp connector, whereby first and second clamp devices having a pair of clamp bodies engage opposing faces of the clamp connector, and pressing the pair of clamp bodies together to maintain the closure of the clamp connector.

Typically the first and second clamp devices are spaced apart from one another and are optionally applied to the clamp connector at locations that are diametrically opposed to one another around the circumference of the pipe. An equal spacing between adjacent clamp devices is useful but not essential. Typically the first and second clamp devices are spaced at opposite sides of the clamp connector, on opposite sides of the pipeS Typically the threaded fixings on the clamp connector pass through lugs and are spaced away from the circumference of the pipe. Typically the clamp devices are applied to the lugs on the clamp connector.

Typically the first and second clamp bodies each comprise a plate and typically the plates are pressed together by the force driver when the clamp apparatus is made up.

Typically the first and second clamp devices each have a foot portion.

The foot portion can be a separate or an integral part of the plate.

Typically the plates can have bores extending through them. Typically the bores of the apertures through the plates are aligned with one another, and are connected by means of the threaded stud or bolt etc.. Optionally the plates can have recesses or apertures to receive fixings of the existing clamp connector, so that the plate can be located over the fixings, which typically can pass through the plate or at least extend into the aperture or recess on the plate. By extending through or into the aperture or recess on the plate, the fixing on the clamp connector being supported can help to retain the plate in position on the clamp connector and avoid dislocation of the plate from the clamp connector once force is applied to the clamping device. Optionally, when the plate is located over the fixings of the existing clamp connector, the plate can bear on the nut of the fixings to apply clamping force to the clamp connector.

The force driver device can be a tensioning device such as a threaded fixing e.g. a bolt or threaded stud optionally driven through a threaded socket, or reacting with a threaded member such as a nut. Alternatively hydraulic cylinders can be used.

The driver device can be used to pull or push the flanges together.

Typically the first and second clamp bodies have a pair of bores. Typically the first and second clamp devices of the invention are fixed to the clamp connector such that the bores of the plates are generally parallel to the threaded fixings of the clamp connector. Typically the threaded bolt or stud passing through the bores of the plate are parallel to the threaded fixings connecting the two parts of the existing clamp connector.

Typically the bores are radially spaced in relation to the axis of the connection, allowing the bolt or threaded stud to extend between the clamp bodies without engaging the pipe or the clamp connector. Typically a nut is threaded onto the bolt or stud on the other side of the clamp device, and the threaded action of the nut on the stud or bolt typically provides the axial force to press the two clamp bodies together. The bore can be formed on a collar that is separately attached to the plate, or can be an integral part of the plate. The bores on the first plate are typically lined up with the bores on the second plate.

Typically the clamp device surrounds at least a portion of the clamp connection that it supports.

In certain embodiments of the invention, the force driver device can be a tensioning device. Optionally the force driver can be located between two clamp bodies of each clamping device. The two clamp bodies are typically spaced apart along the axis of the clamping device, and the force driver device can be located between them, operating to pull or push the clamp bodies towards one another.

Two clamping devices are sufficient for most embodiments. Typically, clamping devices are applied between pairs of bolts passing through the clamp connectors, and typically at the central position between adjacent bolts. Typically the apparatus permits the position of the foot against the outer face of the clamp connector to be adjusted, optionally at the mid point between adjacent bolts.

Typically the clamping devices are connected with nuts or other fixings applied to the threaded studs or bolts, etc. to loosely connect the upper and lower plates of the clamping device together before the clamping device is applied across the clamp connector. After the clamping device is applied across the clamp connector, the nuts can be tensioned at one or both ends of the stud in order to move the plates of the clamping device together and engage the outer faces of the opposing parts of the clamp connector. When the clamping device is made up in this way with the stud interconnecting the clamp bodies, the upper and lower legs are typically a mirror image of one another, and the plates of the upper and lower clamp bodies are typically in alignment with one another.

When the foot has been positioned against the clamp connector on each side of the clamp connector, in between adjacent bolts, and the nuts on the threaded studs have been tensioned in order to loosely clamp each clamp device in place across the flanged connection, this process is repeated until the required number of clamp devices have been applied across the clamp connection. Typically two clamp devices will be applied across the clamp connection to be supported (one on each side), but more can optionally be applied, especially if this permits the clamping apparatus of the invention to apply a generally even clamping force around the clamp connector. Optionally, it will be sufficient for one clamping device to be applied in between each adjacent pair of bolts.

Optionally a link arm can connect spaced apart clamp devices together.

The link arm can optionally be used to retain the clamp devices in position on the clamp connector being supported, and can stabilise the clamp devices as they apply forces to the clamp connector. The link arm can optionally transfer forces between the linked first and second clamp devices, to equalize the forces applied by the clamp apparatus.

The primary tensioning force across the clamp connector is typically applied by tensioning the studs passing through the clamp bodies. In general, the tension in the threaded studs is increased while measuring the tension in the existing bolts that pass through the clamp connector being supported. The tension in the new threaded studs passing through the plates is increased until the tension in the bolt passing through the existing clamp connector approaches zero, at which time, the newly applied threaded studs are applying the same tension to the flange that was previously applied by the existing bolts, which are therefore redundant. By applying the same tension via the threaded studs on the clamping device of the invention as was previously applied by the existing bolts that passed through the clamp connector, the remedial method according to the invention avoids changing the internal conditions on the inner faces of the flange, and thereby avoids disturbing the seal as much as possible, thereby reducing the extent of the intervention. The clamping force applied across the flanged connection is therefore gradually increased until the force compressing the flanges is the same as it was before intervention, but instead of being applied through the existing bolts, it is being applied through the newly applied clamping device of the invention. In this way, structurally intact threaded studs and other components of the invention which are applied to an older failing clamp connection can be certified for use for a further period of time to coincide with or extend beyond the expected lifetime of the flanged connection and the pipeline itself, without disturbing the existing bolts. These can optionally be left in place if desired, as they no longer apply any force, or can optionally be removed according to operator preference.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:-Fig. I shows a perspective view of a flanged connection secured by bolts which are nearing the end of their serviceable life, and having a clamping apparatus in accordance with one embodiment applied around the flanged connection; Fig. 2 shows a side view of the Fig. I embodiment; Fig. 3 shows a plan view of the Fig. I embodiment; Fig. 4 shows an end view of the Fig. I embodiment; Fig. 5 shows a perspective view of the same flanged connection having a second embodiment of a clamping apparatus in accordance with one embodiment applied around the flanged connection; Fig. 6 shows a side view of the Fig. 5 embodiment; Fig. 7 shows a plan view of the Fig. 5 embodiment; and Fig. 8 shows an end view of the Fig. 5 embodiment.

Referring now to the drawings, Fig. 1 shows a pipeline P (shown in dotted lines for clarity in Fig 1) having a flanged connection comprising a pair of flanges F. The flanges are connected by a known design of clamp connector C (typically a GRAYLOCtm connector) comprising a pair of hubs H joined by bolts B passing through holes in the lugs at the ends of the hubs H so that the bolts B are parallel to one another and perpendicular to but radially spaced from the axis X of the pipe P. The bolts B are typically arranged at outside ends of the lugs, so as to equalise the clamping pressure they apply. The lugs have outer faces which are engaged by nuts N, which are screwed onto the bolts B to force the hubs radially towards one another over the flanges F. This presses the flanges together in a known manner.

When the bolts B have been corroded to an extent that requires their replacement, a clamping apparatus 10 according to the invention is applied around the clamp connector C by the following method.

The clamping device 10 comprises a number of individual clamping devices in the form of clamp members 15. Each clamp member 15 comprises upper and lower clamp 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 passes through an aperture on a collar 18 on each body 16. The apertures on the collars 18 are aligned, and each clamp member 15 is symmetrical around the midway point of the stud 17. Each collar 18 is welded or otherwise connected onto an outer end of a respective link arm 20a, 20b. The link arms 201, 20b extend circumferentially around the hubs H and their other (inner) ends interconnect between the two clamp members 15 at diametrically opposite positions on the pipe P, around the midpoint of the hubs H. The outer end of each arm 20 typically has a heel portion 21 which is welded or otherwise connected to the opposing inner faces of the arm 20.

The heel portion 21 bears against the upper surface of the lug of each hub H, and is typically formed with a wedge shape so that the thin end of the wedge can be inserted between closely spaced nuts N on the outer surface of the lug to apply force onto the lug without engaging the nuts N. The ends of the studs 17 extending axially beyond the collars 18 are capped with a nut 17n in order to drive the clamp bodies 16 towards one another when the nuts 17n are tightened.

The clamping apparatus 10 is assembled around the connector C as follows. Initially, a clamp member 15 is made up by loosely connecting the clamp bodies 1 6a,b via the threaded stud 17 and loosely tensioning the nuts 17n to hold the assembly together. Each clamp body 16a, b is then placed typically equi-distantly between adjacent bolts B. The wedge-shaped heel 21 of each clamp body 16 has a narrowed inner end, which is placed radially inward on the upper face of the lug, closest to the hub H. The narrowed inner end of the heel 21 can typically pass into the space between the bolts B that extend through the lug of the hub H, and typically does not interfere with the bolt B or the nuts N on the ends of them. Once each heel 21 is disposed in approximately the mid point between adjacent bolts B on the lugs, the nuts 17n on the stud 17 are adjusted to assemble and retain each clamp member 15 across the connected lugs of the hubs H. Note that in some embodiments of the invention, more than one clamp member 15 can be applied to each lug. The link arms 20 interconnect at a pivot point 20p, and each arm 20 arc over the hub H at approximately the same radius so that the linked arms 20 are spaced radially from the hub H when the clamp members 15 are tensioned up. Linking the clamp bodies 16 on either side of the pipe P transfers forces between the clamp bodies 16 as they are tensioned, and equalises the forces applied to the hubs H. When clamp members 15 have been applied across the lug and loosely tensioned so as to remain in place. At this stage, the clamp members 15 are typically fixed in position and can be tensioned. Before final tensioning of the clamp members 15, the circumferential position on the lug can be adjusted in order to equalise the force applied across the lugs. Once correctly positioned, each stud 17 can be tensioned by tightening the nuts un to draw the clamp bodies 16 axially towards one another thereby pressing the hubs H together. The radial force applied to the hubs H forces the flanges F axially together.

While the tension is being applied across the clamp members 15, typically the tension in the existing bolts B extending between the hubs H can be measured by known tension measurement devices and monitored as the tension is increased through the clamp members 15 until the tension in the existing bolts B approaches zero. At this point, when it can be determined that the existing bolt B is no longer holding any of the radial load across the hubs H, the stud 17 is left at that tension in order to avoid changing the local force applied across the flanges F at that particular bolt. This process is repeated for each of the clamping members 15, with the result that the load experienced by the flanges F before and after the application of the clamping apparatus 10 is generally the same as it was before intervention, and the internal conditions of the seal at the inner faces of the flanges F are not disturbed by the remedial operations.

Once the radial load across the hubs H is transferred completely to the clamping apparatus of the invention, the existing bolts B can be removed or alternatively can be left in place according to operator preference, but significantly, as they are not bearing any of the load across the flanged connection, their further degradation and subsequent failure due to corrosion or other factors will have substantially no effect on the integrity of the connection.

Referring now to Figs. 5-8, the same pipe P and flanged connection with flanges F and bolts B is being repaired by an alternative embodiment of the invention. In this embodiment, similar components to those described in relation to the first embodiment have similar reference numbers prefaced by "1". In the second embodiment of the clamping device 110 there are similarly a number of individual clamping devices in the form of clamp members 115. Each clamp member 115 comprises an upper and lower clamp plate 11 6a, 11 6b, which are mirror images of one another typically and are interconnected by threaded shaft 117, extending through apertures 118 in the plates 116. The apertures 118 are typically parallel to one another and line up in the assembled clamp member 115. The clamp member 115 is generally symmetrical around the midpoint of the shaft 117. The plates 116 are not interconnected between the two sides of the hub I-f, but are instead provided with a pair apertures or recesses 120 located between the apertures 118, and similarly aligned in the assembled clamp member 115. The recesses 120 typically line up with the bolts B on the clamp connector C, so that the threaded shafts of the bolts B extend into the recesses 120 and stabilise the plate 116 on the lugs of the hubs H when tension is applied. When the recesses 120 comprise blind ended cavities the plate will apply force to the stud or bolt, and when an open aperture is provided through the plate instead, the threaded stud will pass through the aperture allowing the plate to apply force to the nut instead.

This allows the operator to select which component (stud or nut) to apply force to depending on the structural integrity of the components. Typically the operator will select the open aperture variant if the nut retains sufficient integrity to withstand the forces applied by the clamping devices 115.

The clamping apparatus 110 of the second embodiment is assembled around the connector C as follows. Initially, the clamp plates 116 are connected by the studs 117 and loosely made up before the plates 118 are placed over the existing bolts B or other studs etc that extend through the outer faces of the lugs on the hubs H. The plates are positioned so that the ends of the bolts B on the lugs extend into the recesses 120 on the plates. When clamp members 115 have been applied across the lugs and are correctly positioned, the nuts 11 7n on the studs 117 can be tightened to apply force to the hubs H. While the tension is being applied across the clamp members 115, typically the tension in the existing bolts B across the hubs H can be measured by known tension measurement devices and monitored as the tension is increased through the clamp members 115 until the tension in the existing bolts B approaches zero. At this point, when it can be determined that an existing bolt B is no longer holding any of the axial load across the hubs H, the clamp member 115 is left at that tension. This maintains the local force applied across the flange at each particular bolt.

This process is repeated for each clamp member 115, with the result that the load experienced by the flange before and after the application of the clamping apparatus is generally not less than as it was before intervention, and the internal conditions of the seal at the inner faces of the flanges F are disturbed as little as possible by the remedial operations.

Once the radial load across the hubs H and thus the axial load across the flanges F is transferred completely to the clamping apparatus of the invention, the existing bolts B across the hubs H can be removed or alternatively can be left in place according to operator preference, but significantly, as they are not bearing any of the load across the flanged connection, their further degradation and subsequent failure due to corrosion or other factors will have substantially no effect on the integrity of the connection.

Optionally each plate 116 can have a heel portion 121 extending from its inner face to bear against the outer face of the lug on the hub H. The heel 121 is typically wedge shaped and can extend into the space between the nuts N to transfer force from the plate 116 to the hub H. This allows less force to be transmitted through the nuts N and the bolts B, which can optionally be removed in certain cases.

Modifications and improvements can be incorporated without departing from the scope of the invention.

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.

Removal of a corroded bolt from an existing in situ clamp connection usually requires interruption of the flow through the pipe, which can have significant adverse economic consequences in the case of oil pipelines and other high value fluid transfer pipelines. Certain embodiment of the present invention typically allow individual bolts or threaded studs making up clamp connectors to be removed and replaced one at a time, while the pipeline remains an active fluid conduit with fluids passing through the connection being repaired. Alternatively corroded bolts making up clamp connectors can be left in place and supported by certain embodiments of the clamp of the present invention.

Claims

CLAIMSI Pipe clamping apparatus for supporting a clamped connection between two flanged pipes, the pipes having a central axis, and having flanges extending radially from the central axis, with a clamp connector fixed across the flanges by means of threaded fixings connecting two parts of the clamp connector wherein at least one of the two parts of the clamp connector moves radially with respect to the central axis of the pipe to clamp the flanges together, the clamping apparatus comprising: first and second clamp devices adapted to be applied to spaced portions of the clamp connector, each of the first and second clamp devices having a pair of clamp bodies adapted to engage opposing faces of the clamp connector, and a force driver device adapted to press the pair of clamp bodies together.
2 Apparatus as claimed in claim 1 wherein the first and second clamp (0 devices are spaced apart from one another and are applied to the clamp connector at locations that are diametrically opposed to one another around the circumference of the pipe.
3 Apparatus as claimed in claim 1 or claim 2, wherein the clamp devices are spaced equidistantly around the circumference of the pipe, on opposite sides of the clamp connector, and on opposite sides of the pipe.
4 Apparatus as claimed in any preceding claim, wherein the threaded fixings on the clamp connector pass through lugs and are spaced away from the circumference of the pipe.
Apparatus as claimed in claim 4, wherein the clamp devices are applied to the lugs on the clamp connector.
6 Apparatus as claimed in any preceding claim, wherein the first and second clamp bodies each comprise a plate and wherein the plates are pressed together by the force driver when the clamp apparatus is made up.
7 Apparatus as claimed in claim 6 wherein the plates have bores extending through them, and wherein the bores in respective plates are aligned with one another, and are connected by means of the threaded fixing.
8 Apparatus as claimed in claim 6 or claim 7 wherein the plates have recesses or apertures to receive fixings of the existing clamp connector, so that the plate can be located over the existing fixings and apply force to the connection without requiring movement of the existing fixings.

(0
9 Apparatus as claimed in any preceding claim, wherein the first and second clamp devices each have a foot portion.
10 Apparatus as claimed in any preceding claim, wherein the force driver device comprises a threaded fixing reacting with a threaded member.
11 Apparatus as claimed in any preceding claim, wherein the force driver device comprises a hydraulic device.
12 Apparatus as claimed in any preceding claim, wherein the first and second clamp bodies each have a pair of bores arranged to be generally parallel to the threaded fixings of the clamp connector, and wherein the bores in the clamp bodies are aligned with one another and are generally parallel to the threaded fixings connecting the two parts of the existing clamp connector, wherein the bores are radially spaced from the axis of the connection, allowing the bolt or threaded stud to extend between the clamp bodies without engaging the pipe or the clamp connector.
13 Apparatus as claimed in any preceding claim, wherein the clamp device surrounds at least a portion of the clamp connection that it supports.
14 Apparatus as claimed in any preceding claim, wherein the apparatus permits adjustment of the position of the foot against the outer face of the clamp connector. r.
Apparatus as claimed in any preceding claims, wherein the clamping devices are connected with nuts or other fixings applied to threaded studs or bolts to loosely connect the upper and lower plates of (0 the clamping device together before the clamping device is applied across the clamp connector.
16 Apparatus as claimed in any preceding claim, comprising a link arm connecting spaced apart clamp devices together.
17 A method of supporting a clamp connector connecting two flanged pipes, the pipes having a central axis and having flanges extending radially from the central axis, with the clamp connector fixed across the flanges by means of threaded fixings connecting two parts of the clamp connector, the method comprising: applying first and second clamp devices around the clamp connector, whereby first and second clamp devices having a pair of clamp bodies engage opposing faces of the clamp connector, and pressing the pair of clamp bodies together to maintain the closure of the clamp connector.
18 A method as claimed in claim 17, wherein the tension in the threaded fixings connecting the clamp bodies is increased while measuring the tension in the existing bolts that pass through the clamp connector being supported until the tension in the existing bolts passing through the existing clamp connector approaches zero.
19 A method as claimed in claim 18, wherein the existing bolts are removed once the tension in the existing bolts reaches zero. r
20 A method as claimed in any one of claims 17-19, wherein individual existing bolts are removed while fluids pass through the connection being (0 repaired. r