GB2461071A

GB2461071A - Compression pipe coupling tightened by tangential bolt

Info

Publication number: GB2461071A
Application number: GB0811263A
Authority: GB
Inventors: Brian Rex
Original assignee: Crane Ltd
Current assignee: Crane Ltd
Priority date: 2008-06-19
Filing date: 2008-06-19
Publication date: 2009-12-23
Also published as: GB0811263D0

Abstract

A compression type pipe coupling device has tangential bolts 5a, 5b to tighten the compression members 2a, 2b onto the sleeve 1. The compression members can be initially turned by hand until a gasket engages the outer diameter of the pipe, and then the gasket is further compressed by applying torque to the tangential bolt. There may be a ratchet mechanism (figure 6), or the bolt may be connected to the sleeve 1 of the coupling by a band clamp (figure 7). The sealing gasket may have a 'waffle' or 'pocketed' profile to assist in sealing corroded or pitted pipes. The coupling is particularly useful for large diameter pipes where conventional compression fittings are not possible because of the torque required.

Description

I

PIPE COUPLING

This invention relates to pipe coupling and in particular to pipe couplings which include gripping elements. In particular, the invention provides a novel coupling arrangement which provides various advantages over prior known coupling arrangements with gripping elements.

Gripping pipe couplings are conventionally assembled to pipe using either bolts that span axially the entire length of the coupling (see for example European Patent No. 0709612) or shorter bolts that connect the end ring of the coupling to the sleeve via lugs on the sleeve end allowing independent tightening of each end of the sleeve (see for example EP 0472379 Bi and EP1292792 Bi).

A disadvantage of axial bolted couplings is that they require a plurality of bolts arranged circumferentiafly around the coupling. In narrow repair trenches or locations with restricted space due to the presence of other utilities equipment, it can be difficult and time consuming for repair and maintenance engineers to properly install bolts. This may result in repair and maintenance engineers omitting to apply the correct torque or omitting to install one or more bolts completely which will reduce the life of the coupling.

Where shorter bolts are used, these require lugs on the sleeve or flange adapter and thus increase weight and cost of the coupling. Also, the lugs are vulnerable to damage or breakage at the higher loads due to torque, S..

internal pressure or axial pipe loading.

Where a plurality of bolts is used to secure the coupling, uneven *.S tightening and in particular over tightening of the bolts can lead to *:::: potential overstreSsiflg of the sleeve and flange adaptor bolt lugs which may result in failure. Alternatively, if bolts are under torqued, this can lead to under compression of the gasket causing premature leakage of the joint. Because of the poor visibility of all the bolts it is not possible to attach any load indicators that rely on visual feedback.

Threaded couplings have, in the past been used for smaller diameter and non gripping couplings though have previously proven problematic in larger diameter couplings. A major obstacle in large size diameter pipes (eg above 50mm nominal size) is the effort required to advance the "nut"/end ring onto the sleeve. Manufacture of suitable threads proved prohibitively costly.

The use of tangential bolts is known but again is impractical with large pipe diameter couplings (particular in the larger outside diameter range) as the bolt length required is prohibitively long and conflicts with the coupling components and clearances with adjacent pipe work.

Gaskets used for sealing in gripping pipe couplings are known in a variety of shapes including; wedge, square, trapezoidal or L-shaped.

Conventionally, these gaskets are provided with a sealing surface which is plain or circumferentially ribbed. Whilst generally suited to sealing on reasonable quality pipe, these gaskets are prone to leakage when applied to severely pitted, corroded or otherwise badly deteriorated pipe. The problem arises where the synthetic rubber typically used as the gasket body cannot penetrate the deepest variations in the deteriorated pipe surface. This can allow pressurised medium in the pipe to track axially along the pipe surface beneath the gasket allowing the leak to migrate to the extreme axial position and externally of the coupling. Even where * *** circumferential ribs are present, leaks can track circumferentially around :. the pipe and connect with other variations allowing them to cross the * : circumferential ribs over time. S.

S

*. The present invention seeks to provide a coupling securing arrangement which addresses the aforementioned difficulties identified with prior art solutions.

In accordance with the present invention there is provided a pipe coupling device comprising: a sleeve having an end configured to receive therein a plain end of a pipe and being provided with an annular first abutment surface; a compression member arranged to encircle the pipe and having an annular second abutment surface and axially extending collar; a sealing and/or gripping assembly for sealing against and gripping the pipe; and means for drawing the compression member and the sleeve axially together so as to compress the sealing and/or gripping assembly between the first and second abutment surfaces thereby to deform or move the sealing and/or gripping assembly radially inwardly and into sealing and/or gripping engagement with the pipe; characterized in that the means for drawing the compression member and the sleeve axially together comprises; a plurality of thread segments arranged around an outer circumferential surface extending axially from the first abutment surface; a complementing plurality of threads arranged on an opposing inner circumferential surface of the axially extending collar; at least one bolt lug provided on the outer circumference of the sleeve and an adjacent surface of the axially extending collar, the pair configured to receive a tangentially oriented bolt.

Optionally, the means for drawing the compression member and the sleeve axially together further includes a manual adjustment arrangement * ** S operable to locate and hold the sealing and/or gripping assembly against the pipe whilst a suitable load is applied to the tangentially oriented bolt. *S.

* The threads are optionally single or multi-start threads. Thread angle and pitch can be designed to suit the size or size range of the coupling.

Desirably the thread design is balanced against the necessary bolt length to provide suitable load on the sealing and/or gripping assembly but in an arrangement with a sufficiently short bolt to facilitate easy location and adjustment of the coupling. For a consistent bolt load and mechanical advantage, as the coupling diameter increases, the load required to compress the sealing and/or gripping assembly also increases and so thread angle is decreased. Simplistically, as the diameter of the subject pipe doubles so does the bolt load required to compress the same sized gasket. Assuming one bolt on a coupling the angle of the bolt will need to be reduced by approximately 50Db to deliver double the axially directed load to compress the gasket.

Conveniently, the manual adjustment arrangement is provided in the form of a ratchet mechanism, optionally associated with either one of the sleeve or the compression member, which is configured to engage when the compression member is rotated manually so as to compress the sealing and/or gripping assembly into sealing and/or gripping engagement with the pipe.

In one example, a ratchet mechanism is provided in the form of suitably positioned ramps or castellations provided on an end surface of the axially extending collar configured to engage behind protrusions provided on an opposing surface of the sleeve. Alternatively, the protrusions may be provided on the axially extending collar and the ramps or castellations on the opposing surface of the sleeve.

Manual rotation of the compression member to engage the sealing and/or *:*:: gripping assembly onto the pipe surface may be assisted by one or more S...

nuts cast into an exposed surface of the compression member via which leverage can be applied by means of spanner or wrench.

In an alternative manual adjustment arrangement, engaging surfaces of *: the sleeve and compression member may comprise series of complementarily shaped protrusions on which a lever can react when the compression member is manually rotated so as to engage the sealing and/or gripping member with the pipe surface. Optionally, one of the complementary surfaces may be provided in the form of a cog wheel (located on either of the compression member or the sleeve).

Optionally, the pipe coupling device further comprises a load indicator associated with the bolt, the indicator being configured to signal to an operator installing the coupling device that a predetermined load has been applied. The load indicator may take any known form and the signal produced may optionally be audible, visual or both. The signal may be relayed directly or remotely from the indicator.

For example, but without limitation, the load indicator may comprise a load indicating washer located on the bolt and subjected to load as the fastener is tightened on the bolt and responsive to the predetermined load to signal to the operator that the predetermined load has been applied.

Conveniently, the load indicator is a visual indicator which is positioned to be continually visible to the operator when the coupling is being installed.

Optionally the sleeve may be cast from iron or steel and can be specifically configured to facilitate casting from a two part pattern to form the outer profile with only an internal core to form the inner profile.

Specific configuration may include careful design of the shape and placement of the sleeve outer protrusions and the general outer profile.

* The later design features enable the draft angles to be such as to allow the pattern halves to withdraw freely from the sand mould. * .*. * S S...

:. In another aspect, the invention provides a gasket for use as a sealing * *:. member in a pipe coupling device, the gasket provided with a waffled sealing surface. The gasket may be of any suitable cross section but more *: preferably has a cross section selected from; square, round, trapezoidal, ** wedge or L shaped. The gasket may conveniently be used in combination with the novel pipe coupling device described herein but has wider application with other pipe coupling devices of varying construction.

The waffle surface design generally comprises a plurality of ribs which run in two or more directions coinciding to provide a plurality of pockets defined by the ribs. For example, but without limitation, there may be provided a plurality of ribs extending substantially circumferentially of the sealing surface which coincide with a plurality of ribs which run substantially axially of the sealing surface. The design is advantageous in that each pocket is self contained and prohibits migration of a leak from one spot to another. Furthermore, gasket pressure is increase by the design thereby sealing in deeper variations on the surface of the pipe.

Optionally, but without limitation, the pockets may be round, oval, triangular, square, rectangular, trapezoidal or polygonal.

The gasket is particularly suited to use in pipe coupling devices in accordance with the first aspect of the invention. Another aspect of the invention therefore comprises; a pipe coupling device comprising: a sleeve having an end configured to receive therein a plain end of a pipe and being provided with an annular first abutment surface; a compression member arranged to encircle the pipe and having an annular second abutment surface and axially extending collar; a sealing and/or gripping assembly for sealing against and gripping the pipe; and means for drawing the compression member and the sleeve axially * ** together so as to compress the sealing and/or gripping assembly between the first and second abutment surfaces thereby to deform or move the * *** seating and/or gripping assembly radially inwardly and into sealing and/or gripping engagement with the pipe; * .:. characterized in that the means for drawing the compression member and the sleeve axially together comprises; : a plurality of thread segments arranged around an outer circumferential surface extending axially from the first abutment surface; a complementing plurality of threads arranged on an opposing inner circumferential surface of the axially extending collar; at least one bolt lug provided on the outer circumference of the sleeve and an adjacent surface of the axially extending collar, the pair configured to receive a tangentially oriented bolt; a manual adjustment arrangement operable to locate and hold the sealing and/or gripping assembly against the pipe whilst a suitable load is applied to the tangentially oriented bolt, and wherein the sealing and/or gripping member includes an annular gasket having a waffled or pocketed sealing surface.

An embodiment of the invention will now be further described by way of example and with reference to the following figures in which: Figure 1 shows a pipe coupling in accordance with the invention assembled on a pair of pipes; Figure 2 shows an external view of the sleeve of the coupling of Figure 1 Figure 3 shows a perspective view of a compression member of the coupling of Figure 1.

Figure 4 shows a perspective, exploded view of sealing and/or gripping assembly of the coupling of Figure 1 to be located between the sleeve and the compression member.

Figure 5 shows the surface detail of a gasket in accordance with the I...

invention. S.

Figure 6 shows a first embodiment of a manual adjustment arrangement of a pipe coupling device in accordance with the invention. S * S

Figure 7 shows a second embodiment of ratchet mechanism for use as a manual adjustment arrangement of a pipe coupling device in accordance with the invention.

Figure 8 shows a third embodiment of ratchet mechanism for use as a manual adjustment arrangement of a pipe coupling device in accordance with the invention.

As can be seen from Figure 1, the coupling device comprises a cylindrical sleeve 1 which is flared at both ends and configured to screw together with compression members (or end rings) 2a, 2b. A pair of lugs 3 is provided on the outer circumference of sleeve. In addition lugs 4a, 4b are provided on compression members 2a, 2b. The lugs receive bolts 5a, 5b.

As shown pipes P1 and P2 are received at opposing ends of the sleeve.

Pipe P1 has a diameter at the high end of the tolerance diameter for the coupling and pipe P2 has a diameter at the lower end of the tolerance diameter for the coupling. It can be seen that bolts 5a and 5b are secured at slightly different positions in the lugs to accommodate the different pipe diameters.

Figure 2 shows the sleeve in more detail. As can be seen, the sleeve generally comprises a cylindrical body 11 and two flared ends 12, 13.

Each flared end is provided on its outer diameter with multiple male thread starts 14a, 14b, 14c, 14d, 14e, 14f. Lugs 3 are provided to receive and hold bolts (not shown). Also provided are nut casts 15 which can be used to assist in the application of leverage to manually rotate the sleeve and compression member (not shown) together and so compress against the sealing and/or gripping members (not shown). The protruding nut casts 15 also serve to engage on axially inner surface of the compression member to prevent the compression member from being pushed in an axial direction onto the sleeve during transit. This avoids the premature compression of the gasket during transit.

S

The outer portion of the sleeve has been cast in a two part split mould, the split mould line passing between the oppositely oriented lugs 3.

Figure 3 shows a compression member in the form of an end ring configured for engagement with the flared ends 12, 13 of the sleeve of Figure 2. As can be seen, the inner annular surface 21a of the end ring is provided with female thread starts 22a, 22b,22c which cooperate with the male thread starts 14a, 14b, 14c, 14d, 14e, 14f on the outer circumference of the sleeve to secure the end ring to the sleeve. On the outer annular surface 21b of the end ring there is provided a series of protrusions 23a, 23b, 23c, 23d which form part of a ratchet mechanism (described later) for assisting manual rotation of the end ring to engage the gasket and/or gripper assembly onto the pipe surface prior to final loading of the tangential bolt and consequential loading of the end ring against the sleeve.

As can be seen from Figure 4, the sealing and/or gripping assembly comprises a gripping ring 6 supported by an annular gasket 7. As shown, the gripping ring comprises a plurality of interlinked gripping elements.

Figure 5 shows a section of a gasket 7 in accordance with the invention.

As can be seen the sealing surface of the gasket has a substantially L shaped cross section. Moulded into the sealing surface are a plurality of circumferentially arranged ribs 71a, 71b, 71c and a plurality of axially extending ribs 72a, 72b, 72c crossing the circumferentially arranged ribs.

The crossed ribs define a plurality of pockets 73 which assist in sealing in leaks on deeply pitted or corroded pipe. An annu'ar recess 74 on the reverse side of the sealing surface received a gripping or support ring (not *::::* shown).

As can be seen from Figure 6, a first embodiment of a manual adjustment arrangement is in the form of a ratchet mechanism arranged on the compression member (end ring) 60 of a coupling device. The mechanism * comprises a plurality of serrations 61a, 61b, 61c, 61d arranged around the outer circumference of the end ring 60 and a pawl 62 which, in use, is loosely located on the end ring 60, over the serrations 61a, 61b, 61c, 61d and held in position by the tangential bolt 63 which in turn is received through the sleeve lug 64.

In use, an operator manually rotates the end ring 60 onto the sleeve of the coupling device making use of reciprocal screw threads 65a, 65b provided on the engaging surfaces. of the sleeve and end ring 60. As the end ring 60 is rotated, the pawl 62 ratchets over the serrations 61a, 61b, 61c, 61d. As the end ring 60 is tightened, the gasket (not shown) of the coupling device is caused to reduce in diameter and engages with the pipe surface (not shown). At this point, the operator ceases manual rotation of the end ring 60 and applies torque to the tangential bolt / nut arrangement 63. This action promotes the pawl 62 to engage behind the nearest serration and commences further rotation of the end ring 60 under load. A prescribed level of increased tightening of the bolt 63 loads the gasket to the correct gasket pressure.

As can be seen from Figure 7, in a second embodiment of a manual adjustment arrangement a bolt lug 71 is provided on an outer circumference of the compression member (end ring) 70 as part of the casting. A strap 72 of flexible yet strong material (for example but without restriction, stainless steel) is provided which includes an integral toggle wrench arrangement 73. In operation a tangential bolt 74 is located in the lug 71 of the end ring and also in a band toggle lug 75.

In use, an operator manually rotates the end ring 70 onto the sleeve of the coupling device making use of reciprocal screw threads provided on the engaging surfaces of the sleeve and end ring. The gasket (not shown) engages with the pipe surface (not shown). During rotation, the toggle wrench 73 is pushed forward releasing tension in the strap 72 which in turn allows the strap 72 to rotate with the end ring 70 around the sleeve.

When the gasket engages with the pipe, the operator tightens the bolt 74 S. or nut forcing the toggle lug 75 backwards and putting the strap 72 into tension around the sleeve. The strap grips the sleeve surface and as the bolt 74 is further tightened the grip is enhanced allowing the end ring 70 to complete its energising of the gasket.

As can be seen from Figure 8 in a third embodiment of a manual adjustment arrangement, a sleeve 80 of a coupling is provided with a series of ratchet serrations 81a, 81b, 81c, 81d or bosses over which a pawl 82 is able to ratchet. In use, an operator manually rotates the compression member (end ring) 83 onto the sleeve 80 of the coupling device making use of reciprocal screw threads 84 provided on the engaging surfaces of the sleeve 80 and end ring 83. During this operation the pawl 82, which is located on the tangential bolt 85 which in turn is connected to the end ring lug 86, will travel over the sleeve ratchets or bosses 81a, 81b, 81c, 81d. Once the gasket (not shown) is engaged with the pipe (not shown), the operator tightens the bolt or nut 85 thereby loading the pawl 82 and forcing it behind and into engagement with the serrations/ratchets/bosses 81a, 81b, 81c, 81d of the sleeve 80. Further tightening of the bolt 85 rotates the end ring 83 causing compression of the gasket. * II * S * * * S.. * . *S). I. * S * S..

S S.. S... S *S

I

S *0*

S

Claims

CLAIMS1. A pipe coupling device comprising: a sleeve having an end configured to receive therein a plain end of a pipe and being provided with an annular first abutment surface; a compression member arranged to encircle the pipe and having an annular second abutment surface and axially extending collar; a sealing and/or gripping assembly for sealing against and gripping the pipe; and means for drawing the compression member and the sleeve axially together so as to compress the sealing and/or gripping assembly between the first and second abutment surfaces thereby to deform or move the sealing and/or gripping assembly radially inwardly and into sealing and/or gripping engagement with the pipe; characterised in that the means for drawing the compression member and the sleeve axially together comprises; a plurality of thread segments arranged around an outer circumferential surface of the sleeve extending axially from the first abutment surface; a complementing plurality of threads arranged on an opposing inner circumferential surface of the axially extending * ** collar; :::::: at least one bolt lug provided on the outer circumference of the sleeve and an adjacent surface of the axially extending collar, :. the pair configured to receive a tangentially oriented bolt. * *S. *.*
2. A pipe coupling device as claimed in claim 1 wherein the means for **** : drawing the compression member and the sleeve axially together further includes a manual adjustment arrangement operable to locate and hold the sealing and/or gripping assembly against the pipe whilst a suitable load is applied to the tangentially oriented bolt.
3. A coupling device as claimed in claim 1 or claim 2 wherein the threads are multi start threads.
4. A coupling device as claimed in claim 2 or 3 wherein the manual adjustment arrangement is provided in the form of a ratchet mechanism, optionally associated with either one of the sleeve or the compression member, which is configured to engage when the compression member is rotated manually so as to compress the sealing and/or gripping assembly into sealing and/or gripping engagement with the pipe.
5. A coupling device as claimed in claim 4 wherein the ratchet mechanism is provided in the form of suitably positioned ramps or castellations provided on an end surface of the axially extending collar configured to engage behind protrusions provided on an opposing surface of the sleeve, or wherein protrusions are provided on the axially extending collar and the ramps or castellations are provided on the opposing surface of the sleeve.
6. A coupling device as claimed in claim 2 or 3 wherein the manual adjustment arrangement comprises engaging surfaces of the sleeve * ** and compression member each provided with a series of complementarily shaped protrusions on which a lever can react when the compression member is manually rotated so as to :. compress the sealing and/or gripping member. * *..
7. A coupling device as claimed in claim 6 wherein one of the complementary surfaces is provided in the form of a cog wheel ** located on either of the compression member or the sleeve.
8. A coupling device as claimed in claim 2 or 3 wherein the manual adjustment arrangement comprises a strap of flexible yet strong material having an integral toggle wrench arrangement and a toggle lug thereon and wherein the tangential bolt locates both with a lug provided on the outer surface of the compression member and with the toggle lug.
9. A coupling device as claimed in any preceding claim wherein the pipe coupling device further comprises a load indicator associated with the bolt, the indicator being configured to signal to an operator installing the coupling device that a predetermined load has been applied.
10. A coupling device as claimed in claim 9 wherein the load indicator comprises a load indicating washer located on the bolt and subjected to load as the fastener is tightened on the bolt and responsive to the predetermined load to signal to the operator that the predetermined load has been applied.
11. A coupling device as claimed in any preceding claim wherein the sleeve comprises a casting manufactured from a two part pattern to form the outer profile with only one core to form the inner profile of the sleeve when made using the sand moulding technique.

* *
12. A coupling device as claimed in any preceding claim wherein the sealing and/or gripping assembly includes an annular gasket,having a waffled or pocketed sealing surface. * *

*
13. A coupling device as claimed in any preceding claim wherein the sealing and/or gripping assembly comprises an annular gasket * S..supported by, a gripping ring, the gripping ring comprising a . plurality of interlinked gripping elements.
14. A coupling device as claimed in any preceding claim wherein manual rotation of the compression member to engage the sealing and/or gripping assembly onto the pipe surface is assisted by one or more nuts cast into an exposed surface of the compression member via which leverage can be applied by means of a spanner or wrench. * .* * a * * *a *S.. * *S.. * * * *** * ** * * *** * * a ** * * *