GB2227065A - Pipe couplings - Google Patents

Abstract

This invention provides a pipe coupling comprising a plurality of generally arcuate segments adapted to abut one another end to end when fully made up; means for coupling the segments together at their ends, the segment ends having surfaces adapted to engage and slide upon complementary mating surfaces at juxtaposed segment ends during make-up of the coupling; the segments of the coupling being provided with two sets of axially separated keys extending radially inwardly thereof and adapted, in use, to engage in outer annular peripheral grooves in and adjacent the ends of pipes to be jointed by the coupling; and the coupling being provided with an annular sealing gasket disposed between the keys for providing a seal for the pipes jointed by the coupling; the relative disposition of the sliding surfaces at the segment ends and the keys being such that, after said surfaces slide together to the fully made up disposition of the coupling, the keys are, at least in part, inclined to the median plane and the segments are aligned with the median plane, whereby. In use, the keys engage and bear upon side walls of the outer peripheral grooves of the pipes being jointed. <IMAGE>

Description

Pipe Coupling This invention relates to pipe couplings, and more particularly to pipe couplings of the kind adapted to connect together two pipes each having an annular outer peripheral groove formed (by rolling or cutting for example) adjacent the end thereof.

firm ouplings of this the G plur-'-ty cf arcuate segments adapted to be coupled together and, in use and when fully made up (i.e. when tightly connected together), encircle and form a joint between two pipes and hold a sealing gasket of annular configuration into sealing engagement with the external peripheries of the pipes concerned, the arcuate segments being provided with radially inwardly projecting ribs (or keys) which, in use, fit within the annular peripheral grooves of the pipes adjacent the ends thereof to hold the pipes together.

Such pipe couplings both seal and lock the joint between the two pipes.

It is to be understood that the expression pipe as used herein means pipes and tubes as such and also pipelike members and fittings for use in pipework such as bends, elbows, 'T' connectors and parts of devices adapted to be fitted into pipework, such as valves and pumps.

It is also to be understood that the expression "median plane" as used herein in relation to the pipe coupling means the single plane passing generally through the mean of the arcuaLe centre lines of each of the plurality of segments of the coupling when coupled together.

Additionally it is to be understood that the expression "the axis" as used herein in relation to the pipe coupling means the axis passing through the centre of the coupling and at right angles to the median plane.

With je using suzl. coplir, it ic desirable that, in the fully made up condition, the ends of each segment are closely juxtaposed so as to avoid any possibility of the annular sealing gasket being forced or "extruded" between the ends of adjacent segments of the coupling by internal pressure from within the two pipes connected by means of the coupling.Alternative to this requirement on make-up is the provision of complicated and, therefore, expensive arrangements for protection adjacent the ends of the segments of the coupling to resist any tendency of the gasket to be "extruded" by pressure from within the pipe if the ends of the segments are not closely pressed together on final make-up of the coupling in the formation of a joint between two pipes.

Such protection arrangements can, for example, comprise arcuate plates spanning the gaps between segments within the coupling.

Ensuring that the ends of the segments of the coupling are firmly pressed together in the fully made up condition of the coupling means that the coupling, when made up, doe havo a single effective internal peripheral or circumferential length. In view of manufacturing tolerance ranges used in the manufacture and assembly of couplings and pipes, this means that, in practice, the single internal peripheral length of the minimum tolerance range size of coupling must be such as to accommodate the maximum tolerance range size pipe and minimum depth peripheral grooves they ;;^. The prmoeical eff-e of t## is that with the majority of pipes and couplings, the coupling, when fully made up, is not in full metal-tometal radial contact around the pipe, or the grooves therein, although the pipe joint is satisfactorily locked and sealed. The result of this is that it is commonly possible to move the pipes laterally and/or rotationally and/or angularly within the coupling at the joint, so that the desirable attainment of a joint which is firmly rigid and immovable as well as locked and sealed is not readily obtained.

Attempts have been made to resolve the problem of the lack of rigidity of these joints. Thus, proposals have been made for permitting separation between the ends of segments in the fully made up condition of the joint, the segments being connected together and the coupling made up to bear on the pipes without the segment ends necessarily meeting. Such arrangements do, however, require provision for the prevention of extrusion of the gasket from between the ends of the segments, and can introduce mechanical weakness at the segment end when the segments are coupled together.

It has also been proposed to allow sliding engagement between angled end faces of segments on make up of the coupling so that there is not just one fully made up condition of the coupling with a single internal peripheral length, but provision for a variable internal peripheral length to enable thf firr'y held accorroda of pipes within a full manufacturing range of tolerances.

Such an arrangement, however, involves a relatively complicated, and hence expensive, segment end configuration and coupling arrangement.

It is an object of the present invention to overcome or at least substantially reduce the above mentioned problems.

In accordance with one aspect of the present invention, there is provided a pipe coupling comprising a plurality of generally arcuate segments adapted to abut one another end to end when fully made up; means for coupling the segments together at their ends, the segment ends having surfaces adapted to engage and slide upon complementary mating surfaces at juxtaposed segment ends during make-up of the coupling; the segments of the coupling being provided with two sets of axially separated keys extending radially inwardly thereof and adapted, in use, to engage in outer annular peripheral grooves in and adjacent the ends of pipes to be jointed by the coupling; and thb coupling being provider with an annular sealing gasket disposed between the keys for providing a seal for the pipes jointed by the coupling; the relative disposition of the sliding surfaces at the segment ends and the keys being such that, after said surfaces slide together to the fully made up disposition of the coupling, the keys are, at least in part, inclined to the median r nd esn CGt ere ali#r-d with the media plane, whereby, in use, the keys engage and bear upon side walls of the outer peripheral grooves of the pipes being jointed.

In accordance with another aspect of the present invention, there is provided a pipe coupling comprising a plurality of generally arcuate segments having generally radially extending lugs at or adjacent each segment end carrying means for coupling together the segments, the segment ends having surfaces inclined to the median plane and adapted to engage and slide upon complementary mating surfaces at juxtaposed segment ends to turn the segments with respect to the median plane during make-up of the coupling about a pipe; the segments of the coupling being provided with two sets of axially separated keys extending radially inwardly thereof and adapted, in use, to engage in outer annular peripheral grooves in and adjacent the ends of pipes to be jointed by the coupling, and the coupling being provided with an annular sealing gasket disposed between the keys for providing a seal for the pipes jointed by the coupling; the relat"xre disposition of the sliding surfaces at the segment ends and the keys being such that, after said surfaces slide together to the fully made up condition of the coupling, the keys are, at least in part, inclined to the median plane and the segments are aligned with the median plane, whereby, in use, the keys engage and bear upon side walls of the outer peripheral grooves of the pipes being jointed. In one embodiment of the invention, the keys of each segment are, at least in part, inclined to the arcuate centre line of their segment, whereby, in use, loose assembly of the coupling upon the pipes to be jointed with the keys located within the outer peripheral annular grooves of the pipes causes the arcuate centre line of each of the segments to be inclined to the median plane.

During make up the complementary mating surfaces at the ends of the segments slide together to bring the segments into alignment with the median plane whilst causing at least part of the keys of the segments to adopt a line inclined to the median plane so as to bear upon the side edges of the groove of the pipes to be jointed by the coupling.

The complementary mating surfaces may comprise one or more surfaces of a stud protruding from the end of one segment, and one or more surfaces of a recess into the end of the juxtaposed segment.

In one embodiment of the invention axially facing portions of the walls of the keys of the segments may be angled with respect to the inclined line of the keys such that at full make up for a joint incorporating the coupling and pipes, bearing contact between the keys and the side walls of the pipes is over the areas of the angled portions of the keys. This arrangement significantly reduces a major problem of the disposition of the earlier proposal mentioned hereinabove for sliding engagement between inclined end faces of segments, where there is only theoretical point contact between the sides of the segments and the walls of the pipe grooves when the joint is made up, thus leading to undesirable local stress within the joint and pipe ends.

The segments may be coupled together by means of bolts passing through bores in the lugs of the segments, secured with nuts.

The invention includes within its scope a pipe joint incorporating a coupling as herein defined.

In order that the invention may be more readily understood, one embodiment thereof will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a part sectional front elevation of one segment of a pipe coupling according to the invention; Figures 2A and 2B are a scrap views in the direction of arrows A and B respectively of Figure 1; Figure 3 is an under plan view of the segment of Figure 1; Figure 4 is an isometric view of a coupling incorporating two segments of the kind shown in Figure 1 in its open position; Figure 5 is an isometric view of the coupling of Figure 4 in its fully made up condition; Figures 6 and 7 are schematic plan views showing the disposition of the keys of the coupling of Figures 4 and F in pipe grooves before and after being fully made up respectively;; Figures 8 and 9 are schematic side elevations showing the keys and the mating surfaces of the segments of the coupling of Figures 4 and 5 before and after being fully made up; and Figure 10 is a schematic plan view corresponding to Figure 7 showing a modified form of key.

Referring now to the drawings, it will be seen that the coupling is, in principle, of the type comprising a pair of semi-circular arcuate segments 1, 2 having, at each end, lugs 3, 4 and having end surfaces 5, 6 lying in a plane passing through the axis of the coupling and at right angles to the median plane of the coupling. On each axial side of each segment is an internal arcuate rib or key 7, 8 adapted, in operation of the coupling, to engage in corresponding grooves 9, 10 in the pipes 11, 12 to be jointed by the coupling. Within a cavity 13 between the two sets of key, in u, 2r notated an annular sealing gasket (not shown) of common type adapted to provide a seal with the two pipes 11. 12 to be connected.

The lugs 3, 4 are provided with apertures 22, 23 for the receipt of bolts having appropriate nuts (not shown) for coupling the segments together.

It will be observed that the two ends of each segment are not the same. One end is provided with a recess la in its end surface 6 having inclined side walls 15, 16, whilst the other end is provided with a corresponding outward stud 17 from its end surface 5 similarly having inclined side walls 18, 19.

The configuration of the keys 7, 8 in each segment can, in certain regards, best be seen from Figures 3, 6 and 7. In essence, the keys are inclined or offset from a plane parallel to the arcuate centre line of the segment (as indicated by arrows X-X in Figure 3). In addition, the keys have angled side wall portions 20, 21, 24, 25 (Figures 6 and 7) and are of reducing width adjacent the ends of each segment.

The active purpose of the relative inclination of the keys with respect to the arcuate centre line of the coupling segments is apparent when considering Figures 4 to 9 in particular. On placing the coupling loosely about the two pipes 11, 12 to be connected thereby, as can be seen from Figure 6, the keys lie loosely within and along the line of the annular grooves 9, 10 around the outsides of the pipes, whilst the coupling segments themselves are each offset with respect to the median plane. A similar but opposite offset occurs in each of the two segments, so that, at this loosely coupled position, the end surfaces 5, 6 of the segments 1, 2 have a relative displacement to each other as shown by the arrows Y in Figure 8, but with the keys 7, 8 lying gerarally ir. Ilne with each other. hc tt# sare tI###ti..,t '6 downwardly extending stud 17 of one segment end surface 6 locates within but at one side of the complementary recess 14 in the other segment end surface 5 such that complementary inclined surfaces 15, 18 at one side of each of the stud 17 and the recess 14 engage.On tightening the coupling members, (not shown, but comprising in a common manner bolts and nuts) via apertures 22, 23 through the lugs 3, 4 of the ends of each segment 1, 2, the inclined surfaces 15, 18 of the studs 17, and the recesses 14 at each end of the segments 1 and 2 slide over each other so as to turn the segments such that their arcuate centre lines turn into the median plane of the coupling, whereby on being fully made up with the end surfaces 5, 6 of the segments firmly abutting and the coupling defining its single effective inner peripheral length, and with a gasket (not shown) disposed within the coupling for sealing the jointed pipes, the stud 17 of each segment end lies fully within and mating with the recess 14 in the juxtaposed segment end, as is clearly seen in Figure 9.As can also be seen from this Figure aiicl indeed from Figures 5 and 7, at this time, although the segments of the coupling are now fully aligned and no longer offset with respect to each other, the keys are significantly misaligned whereby, as can be seen in Figure 7, the angled side wall portion 20, 21, 24, 25 of the keys end bear at each end upon the side walls of the grooves 9, 10 in the pipes @@ 12 @@@@@@ hold the @@@ @@@@ @@@ ri@@@ @@ well as sealed and locked. As can be seen, the effect of the angled side wall portions of the keys is to enable a significant area of contact between the keys and the side walls and not just point contact, providing greater strength and greater facility to hold the joint firm and rigid.

To enhance gripping of the side walls of the grooves 9 and 10 by the keys 7 and 8, a plurality of raised or sharp projections may be provided on at least some of the angled side wall portions as is shown at 30 and 31 in Figure 10. On tightening the coupling to the Figure 10 position, projections 30 and 31 are forced into the walls of grooves 9 and 10 respectively; greatly assisting the firm location of the joint and preventing rotational movement of the pipes 11 and 12 within the coupling.

By means of the invention we have enabled the provision of a coupling, capable of receiving all pipes within a predetermined tolerance range of outer diameters, heaving single effective internal periphery, which is not only locked and sealed, in use, but is also firmly and rigidly held against axial, rotational and angular movement by virtue of the firm engagement of the keys of the coupling segments with the side walls of the annular grooves around the outside of the pipes.

Claims (8)

CLAIMS:

1. A pipe coupling comprising a plurality of generally arcuate segments adapted to abut one another end to end when fully made up; means for coupling the segments together at their ends, the segment ends having surfaces adapted to engage and slide upon complementary mating surfaces at juxtaposed segment ends during make-up of the coupling; the segments of the coupling being provided with two sets of axially separated keys extending radially inwardly thereof and adapted, in use, to engage in outer annular peripheral grooves in and adjacent the ends of pipes to be jointed by the coupling; and the coupling being provided with an annular sealing gasket disposed between the keys for providing a seal for the pipes jointed by the coupling; the relative disposition of the sliding surfaces at the segment ends and the keys being such that, after said surfaces slide together to the fully made up disposition of the coupling, the keys are, at least in part inclined to the median plane and h segments are aligned with the median plane, whereby, in use, the keys engage and bear upon side walls of the outer peripheral grooves of the pipes being jointed.

2. A pipe coupling comprising a plurality of generally arcuate segments having generally radially extending lugs at or adjacent each segment end carrying means for coupling together the segments, the segment ends having surfaces inclined to the median plane and adapted to engage and slide upon complementary mating surfaces at juxtaposed segment ends to turn the segments with respect to the median plane during make-up of the coupling about a pipe; the segments of the coupling being provided with two sets of axially separated keys extending radially inwardly thereof and adapted, in use, to engage in outer annular peripheral grooves in and adjacent the ends of pipes to be jointed by the coupling, and the coupling being provided with an annular sealing gasket disposed between the keys for providing a seal for the pipes jointed by the coupling; the relative disposition of the sliding surfaces at the segment ends and the keys being such that, after said surfaces slide together to the fully made up condition of the coupling, the keys are, at least in part, inclined to the median plane and the segments are aligned with the median plane, whereby, in use, the keys engage and bear upon side walls of the outer peripheral grooves of the pipes being jointed.

3. A pipe coupling as claimed in Claim 1 or 2 wherein the keys of each segment are, at least in part, inclined to the arcuate centre line of their segment, whereby, in use, loose assembly of the coupling upon the pipes to be jointed with the keys located within the outer peripheral annular grooves of the pipes causes the arcuate centre line of each of the segments to be inclined to the median plane.

4. A pipe coupling as claimed in any one of the preceding claims wherein the complementary mating surfaces comprise one or more surfaces of a stud protruding from the end of one segment, and one or more surfaces of a recess into the end of the juxtaposed segment.

5. A pipe coupling as claimed in any one of the preceding claims wherein axially facing portions of the walls of the keys of the segments are angled with respect to the inclined line of the keys such that at full make up for a joint incorporating the coupling and pipes, bearing contact between the keys and the side walls of the pipes is over the areas of the angled portions of the keys.

6. A pipe coupling c claimed in any one of tb.e preceding claims wherein the segments are coupled together by means of bolts passing through bores in lugs of the segments secured by bolts.

7. A pipe coupling substantially as shown in and as hereinbefore described with reference to the accompanying drawings.

8. A pipe joint incorporating a pipe coupling as claimed in any one of the preceding ciaims.