GB1579421A - Pipe couplings - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO PIPE COUPLINGS (71) We, DURAPIPE LIMITED, a British Company, of Norton Canes, Cannock, Staffordshire, WS11 3NS, England, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly desribed in and by the following statement: This invention relates to a pipe coupling of the kind comprising two tubular parts, each provided with a flange at one end, and in which the two tubular parts are held together with the end faces of their flanges facing each other, by a clamping ring encircling the tubular parts and having an internal groove which receives the flanges, the pipe coupling including a resilient annular seal.

In known pipe couplings of this type, if, as frequently occurs in practice, the two tubular parts are not quite coaxial, then each flange may bear upon the clamping ring at only one point, resulting in the flange and clamping ring being subjected to high mechanical stresses at that point, which may lead to damage to the parts, or distortion thereof, with a consequent failure of the seal to operate effectively.

It is an object of the present invention, in one of its aspects, to provide an improved pipe coupling of the above noted type.

According to this aspect of the present invention there is provided a pipe coupling comprising two tubular parts each provided with a flange at one end, a clamping ring having an internal groove into which the flanges extend when the coupling is assembled with the two tubular parts disposed in end to end relationship with their flanges together, the coupling including an annular seal which seals each of said tubular parts with respect to the other when the coupling is assembled, and wherein each of said flanges, in axial section through the respective tubular part, on its side which is furthest from the other of said flanges, slopes outwardly from the periphery of the tubular part towards said one end thereof, whereby when the coupling is assembled, and the clamping ring is tensioned circumferentially, the circumferential tension in the clamping ring produces a wedging action urging one flange into engagement, via the end face of its flange which faces towards the other flange, with the corresponding end face of the other flange, and wherein said internal groove in the clamping ring has side walls, defining the axial limits of the groove, which side walls, in axial section through the coupling, are radiused in the region of their free edges, whereby said side walls flare towards the edges of the groove, the arrangement being such that when the clamping ring is tensioned circumferentially, each said side wall of the groove engages the sloping side of the respective flange only along a continuous line of contact of the radiused part of the groove side wall with the sloping side of the respective flange.

By virtue of this construction, the clamping ring can engage each flange all round the tubular parts more reliably thus avoiding more reliably the localised stresses which can occur with prior art pipe couplings.

Preferably the annular seal is in the form of a resilient, e.g. elastomeric element which in axial section has the form of a channel, open on the radially inner side of the element and has a restricted mouth defined between two lips in the form of flanges extending towards each other from the side of said channel, the annular seal, in the assembled pipe coupling being accommodated between the bottom of the groove in the clamping ring and the peripheral surfaces of the flanges of the tubular parts with each lip engaging the peripheral surface of a respective one of the flanges and the junction between the flanges in the zone of the restricted mouth of the seal, whereby fluid under pressure within the tubular parts, escaping between the end faces of the flanges thereof will tend to inflate the seal and thus urge said lips even more firmly into sealing engagement with the peripheral surfaces of the flanges of the tubular parts.

Preferably, in order to assist this inflating action on the seal, that end face of the flange of each tubular part which faces towards the flange of the other tubular part is provided with at least one groove extending there-across from the radially inner to the radially outer edge of the flange, the or each said groove providing a passage for fluid within the tubular parts to the interior of the seal.

One embodiment of the invention com prises a pipe coupling for connecting adjacent ends of pipes which have their axes inclined with respect to one another.

in laying a pipe line comprising interconnected rigid pipes along a path which includes bends, difficulties arise in following the bends, since in general it is not desirable or practicable to attempt to bend an initially straight length of pipe to conform with a bend, and so it is necessary to employ relatively short tubular connecting pieces formed with a bend in manufacture.

However, for reasons of manufacturing economy it is impracticable to manufacture such preformed tubular connecting pieces with bends of more than a few standard angles, so that the path of such a pipe line must be adapted to a form obtainable by use of the standard fittings and therefore a path for the pipe line must frequently be chosen which is neither the most economical nor the most convenient in other respects.

In said one embodiment of the present invention the pipe coupling for use in a bend in a pipeline, is adaptable to bends of a range of different angles.

In this embodiment, each of said two tubular parts comprises a first end portion provided with the respective said flange and a second end portion adapted for sealing connection with a respective pipe, each said flange being circular and defining a first axis of the respective pipe part, about which first axis the respective said flange is rotationally symmetrical, whereby the two pipe parts can be connected via their said flanges and said clamping ring, in any desired angular position with respect to the other about the coincident said first axes of the connected pipe parts, each said second end portion defining a respective second axis, which when a pipe is connected thereto corresponds to the axis of the latter pipe, said second axis of each tubular part being inclined with respect to the first axis thereof, the arrangement being such that with said first end portions connected together via their flanges, with said first axes coincident, in any angular position of the pipe parts with respect to one another about said coincident first axes, said second axes of said tubular portions intersect at a point on the coincident said first axes or pass a common point on the coincident first axes at a distance small in relation to the diameter of said tubular portions.

Embodiments of the invention are described below with reference to the accompanying drawings in which: Figure 1 is a longitudinal sectional view of a first form of pipe coupling embodying the invention, Figure 2 is an elevation view, looking in the axial direction, of a clamping ring forming part of the embodiment of Figure 1, Figure 3 is a sectional view of a seal forming part of the embodiment of Figure 1, Figure 4 is an end view looking in the axial direction, of one of the tubular parts of the embodiment of Figure 1, Figure 5 is a longitudinal sectional view of a pipe coupling forming another embodiment of the present invention, Figure 6 is a view in longitudinal section of the coupling of Figure 5 with the clamping ring and seal omitted, showing the two tubular parts of the coupling at a different angle with respect to each other as compared with Figure 5, and Figure 7 is a longitudinal sectional view showing a coupling comprising one tubular member of the type shown in Figures 5 and 6 and one straight tubular member of the type shown in Figure 1, the clamping ring and seal being again omitted.

Referring to Fig. 1, a pipe coupling comprises identical tubular parts 1 and 2, each adapted to receive and be secured to, e.g.

by adhesive, a respective end part of a respective one of two pipes to be coupled.

Each part, 1 and 2 is of uniform circular cross-section over most of its length and has at one end a flange la, 2a, extending radially outwardly from the exterior of the tubular part. Each flange has a planar end face Ib, 2b at the end of the respective tubular part and perpendicular to the axis of the latter, and defining one axial limit of the flange. The parts 1 and 2 are held together with their faces lb, 2b facing each other, by a clamping ring 3, formed in two semi-circular halves clamped together by bolts.

The ring 3 has an internal circumferential groove 4, a radially inner part of which receives the flanges la, 2a, the flanges being confined axially between side wall parts 5 of the groove 4, the side wall parts 5 lying in planes perpendicular to the axis of ring 3. A resilient seal 6, of the cross sectional shape shown, is accommodated within a bottom part of the groove 4 between the bottom of the groove and the cylindrical peripheral surfaces of the flanges la, 2a. The seal has the form of a channel open on its radially inner side, and having a restricted mouth defined between lips 8, each of which engages the peripheral surface of a respective one of the flanges la, 2a.

The seal 6 is intended to be inflated by fluid under pressure escaping from within the pipes coupled between the faces 1b, 2b so as to urge the lips 8 firmly into sealing engagement with the respective flanges la, 2a.

The surface 10 of each flange la, 2a which faces away from the other flange is not planar and perpendicular to the axis of the pipe part, but is frusto-conical in form so that in axial section, as shown, each said surface 10 slopes outwardly from the cylindrical exterior surface of the major portion of the respective part 1, 2 towards the end face ib, 2b, of the respective flange. Fur thermore, the radially inner edge of each side wall part 5 of the clamping ring 3 is radiussed as indicated at 5a, each radiussed edge 5a bearing upon the sloping face 10 of the respective flange la, 2a.

Thus when the ring 3 of Figure 1 is tightened, the wedging action between the sloping faces 10 and the respective edges 5a forces the flanges la, 2a, in opposite axial directions, forcing the end faces Ib, 2b of the flanges into full engagement with each other, while because the parts 1, 2 and 3 remain in axial alignment, each flange la, 2a is engaged by a respective edge Sa all round the coupling and not merely at one point. The radial extent of the side walls 5 is, of course, such that despite manufacturing tolerances, the faces ib, 2b are forced into engagement with each other while there is still radial clearance between the ring 3 and the radially outer cylindrical peripheral surfaces of the flanges la, 2a. The fact that the edges 5a of the clamping ring are radiussed is significant, since this feature, in conjunction with the slopes of the faces 10 ensures that each edge 5a makes linear contact with the respective face 10 along a continuous line extending entirely around the respective flange la, 2a.

Figure 2 is an elevation view of the clamping ring 3 of Figure 1, viewed in the axial direction. The ring 3 of Figure 1 comprises, as indicated above, two generally semi-circular parts, indicated at 3a and 3b, and these have at their ends respective lugs 12 extending radially outwardly from the body of the respective part 3a, 3b and provided with holes through which pass bolts 14, on which are engaged nuts 150, by means of which the parts 3a, 3b can be drawn together to tighten the ring 3 about the flanges of the parts 1 and 2 (not shown in Figure 2). Gussets 16 extend between the body of each ring part 3a, 3b and each of the respective lugs 12, one gusset 16 being provided at each axial end of each lug 12, so that each nut 150 and the head of each bolt 14 is located axially (at least in part) between two axially spaced gussets 16.

Figure 3 shows the cross-sectional shape of the seal 6 in the unstressed condition, i.e.

before fitting in the coupling. It will be noted, by comparison with Figure 1, that in the installed state the lips 8 are already resiliently flexed radially outwardly from their unstressed positions, even without any pressurized fluid within the seal, and thus bear sealingly against the peripheral surfaces of the flanges la, 2a.

Since, in the coupling of Figure 1, the faces lb, 2b of the flanges la, 2a are held permanently in engagement with each other, in order to ensure that pressurized fluid from within the parts 1 and 2 can pass to the interior of the seal 6, each end face ib, 2b is provided with one or more shallow grooves 15 extending radially from the inner to the outer edge of the end face lb, 2b.

In Figure 4, which shows an elevation view, looking in the axial direction, of the end face 1b, four such grooves 15, spaced at 90" intervals about the axis of the pipe part, are shown.

Referring to Figure 5, the adjustable coupling shown comprises two identical tubular parts 110 and 112 having first end portions thereof provided with annular flanges 110a and 1 12a respectively and having second end portions thereof formed with sockets 110b and 1 12b respectively.

The flanges 110a and 112a have each an external form the same as that of the flanges la, 2a of Figure 1 and have each a planar end face of the same form as the end face lb, 2b and thus having radial grooves, corresponding to groove 15, extending thereacross.

The two parts 110 and 112 are held together via their flanges in exactly the same way as the parts 1 and 2 in Figure 1 by means of a clamping ring 3 incorporating a seal 6, the ring 3 and the seal 6 being of the same form, and acting in the same way, as the correspondingly referenced parts in the coupling of Figures 1 to 4. The periphery of each flange 110a, 112a, is provided by a cylindrical surface the longitudinal axis of which corresponds to a first axis of the respective tubular part, the said first axes of the two tubular parts being coincident in the assembled coupling and being indicated at 114 in Figure 5. The sides 110c 1 12c of the flanges are formed as respective frustoconical surfaces each symmetrical about the respective first axes (114) and the annular end faces of the flanges are centred on said coincident first axes.

The socket 110b, 1 12b of each tubular part 110, 112 respectively is provided within a generally cylindrical portion of the respective tubular part, the axis of the last mentioned cylindrical part constituting a second axis 110d 112d of the part 110 or 112 respectively, the internal wall of the respective socket 110b, 1 12b being cylindrical and having its axis coincident with the respective second axis 110d or 112d.

The second axis 1 10d or 1 12d of each part 110 or 112 intersects the first axis 114 at a point in the plane of the planar end face of the respective flange 110a or 112a, that is to say in the centre of the annulus defined by the respective planar end face and since, in the assembled coupling, the planes of these end faces are also coincident, the axes 1 lox and 1 12d intersect each other and the axis 114 at a single point the position of which remains the same whatever the ang]e of one tubular part 110 or 112 with respect to the other about the axis 114. As a result, by rotating one tubular part 110 or 112 with respect to the other (112 or 110 respectively) about the axis 114, the angle of the axis 110d with respect to the axis 1 12d can be varied over a continuous range of angles in each of which the distance of the end of each socket 1 lOb, 1 12b from the point of intersection of the axes 110d and 1 12d is the same, so that the coupling has all of the advantages of a bendable connecting piece without the disadvantages which would make a unitary bendable connecting piece impracticable.

In the embodiment shown, the axes 110d, 1 12d are each inclined at 15 with respect to the axis 114, so that by rotating the part 112, for example, with respect to the part 110 through an angle of 1800 about the axis 114 from the position shown in Figure 5 (in which the axes 110d, 112d and 114 all lie in a common plane), the inclination of the axis 112d with respect to the axis 110 can be varied continuously from 30 to 00, an inclination of 0 corresponding to the state illustrated in Figure 6 in which the axes 110d and 1 12d are coincident. Such rotation of one tubular part with respect to the other will, of course, not be readily effected when the clamping ring 116 is fully tightened, and the coupling is preferably adjusted to achieve the desired angle between the sockets 110b and 112b with the parts located somewhat loosely, before the clamping ring is tightened fully.

It will be evident that the range of angles obtainable between the sockets 110b and 112b may be increased by making the inclination of the second axis 110d, 1 12d with respect to the first axis of each part 10 or 12 respectively greater, but for large inclinations it may be necessary either to make each part 110, 112 longer and more complex in shape to avoid undue restriction of the flow cross-section, and/or to arrange the axes of the sockets with respect to the coincident axes 114 in such a way that the axes 110d, 1 12d do not intersect at the point of intersection of the axis 114 with the plane of the end faces of the flanges, but merely pass fairly close to the last mentioned point at a distance small in relation to the mean diameter of the tubular parts 110 and 112. In this case the axes of the sockets will in general not merely by inclined with respect to each other but will also be slightly laterally offset with respect to each other.

Figure 7 shows how one of the tubular parts which forms the coupling in Figure 5, for example the part 110, can be incorporated with a straight tubular part 122 (of the type used in the coupling of Figure 1) to provide a composite connecting piece providing sockets for respective pipes, the angle between the sockets in this case being invariable. The part 110 and part 122 are held together via their flanges by means of a clamping ring of the same kind as shown in Figures 1, 2 and 5 incorporating a seal such as the seal 6 (the clamping ring and seal not being shown in Figure 7) this being made possible by the fact that externally the flanges of the part 110 and part 122 are identical. Figures 6 and 8 show at 124 end portions of straight pipes received in one of the sockets of the respective coupling, the straight pipes being of an external diameter such as to fit closely within the respective sockets, and being, for example, fixed in the respective sockets by adhesive.

The pipe coupling described with reference to the drawings is intended for pipe systems of thermoplastics materials and the parts 1, 2, 110, 112, and 3 of the coupling described being also of thermoplastics material. The invention is not of course confined to pipe systems of thermoplastics materials nor to couplings made of thermoplastics materials.

WHAT WE CLAIM IS: 1. A pipe coupling comprising two tubular parts each provided with a flange at one end, a clamping ring having an internal groove into which the flanges extend when the coupling is assembled with the two tubular parts disposed in end to end relationship with their flanges together, the coupling including an annular seal which seals each of said tubular parts with respect to the other when the coupling is assembled, and wherein each of said flanges, in axial section through the respective tubular part, on its side which is furthest from the other of said flanges, slopes outwardly

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. and the annular end faces of the flanges are centred on said coincident first axes. The socket 110b, 1 12b of each tubular part 110, 112 respectively is provided within a generally cylindrical portion of the respective tubular part, the axis of the last mentioned cylindrical part constituting a second axis 110d 112d of the part 110 or 112 respectively, the internal wall of the respective socket 110b, 1 12b being cylindrical and having its axis coincident with the respective second axis 110d or 112d. The second axis 1 10d or 1 12d of each part 110 or 112 intersects the first axis 114 at a point in the plane of the planar end face of the respective flange 110a or 112a, that is to say in the centre of the annulus defined by the respective planar end face and since, in the assembled coupling, the planes of these end faces are also coincident, the axes 1 lox and 1 12d intersect each other and the axis 114 at a single point the position of which remains the same whatever the ang]e of one tubular part 110 or 112 with respect to the other about the axis 114. As a result, by rotating one tubular part 110 or 112 with respect to the other (112 or 110 respectively) about the axis 114, the angle of the axis 110d with respect to the axis 1 12d can be varied over a continuous range of angles in each of which the distance of the end of each socket 1 lOb, 1 12b from the point of intersection of the axes 110d and 1 12d is the same, so that the coupling has all of the advantages of a bendable connecting piece without the disadvantages which would make a unitary bendable connecting piece impracticable. In the embodiment shown, the axes 110d, 1 12d are each inclined at 15 with respect to the axis 114, so that by rotating the part 112, for example, with respect to the part 110 through an angle of 1800 about the axis 114 from the position shown in Figure 5 (in which the axes 110d, 112d and 114 all lie in a common plane), the inclination of the axis 112d with respect to the axis 110 can be varied continuously from 30 to 00, an inclination of 0 corresponding to the state illustrated in Figure 6 in which the axes 110d and 1 12d are coincident. Such rotation of one tubular part with respect to the other will, of course, not be readily effected when the clamping ring 116 is fully tightened, and the coupling is preferably adjusted to achieve the desired angle between the sockets 110b and 112b with the parts located somewhat loosely, before the clamping ring is tightened fully. It will be evident that the range of angles obtainable between the sockets 110b and 112b may be increased by making the inclination of the second axis 110d, 1 12d with respect to the first axis of each part 10 or 12 respectively greater, but for large inclinations it may be necessary either to make each part 110, 112 longer and more complex in shape to avoid undue restriction of the flow cross-section, and/or to arrange the axes of the sockets with respect to the coincident axes 114 in such a way that the axes 110d, 1 12d do not intersect at the point of intersection of the axis 114 with the plane of the end faces of the flanges, but merely pass fairly close to the last mentioned point at a distance small in relation to the mean diameter of the tubular parts 110 and 112. In this case the axes of the sockets will in general not merely by inclined with respect to each other but will also be slightly laterally offset with respect to each other. Figure 7 shows how one of the tubular parts which forms the coupling in Figure 5, for example the part 110, can be incorporated with a straight tubular part 122 (of the type used in the coupling of Figure 1) to provide a composite connecting piece providing sockets for respective pipes, the angle between the sockets in this case being invariable. The part 110 and part 122 are held together via their flanges by means of a clamping ring of the same kind as shown in Figures 1, 2 and 5 incorporating a seal such as the seal 6 (the clamping ring and seal not being shown in Figure 7) this being made possible by the fact that externally the flanges of the part 110 and part 122 are identical. Figures 6 and 8 show at 124 end portions of straight pipes received in one of the sockets of the respective coupling, the straight pipes being of an external diameter such as to fit closely within the respective sockets, and being, for example, fixed in the respective sockets by adhesive. The pipe coupling described with reference to the drawings is intended for pipe systems of thermoplastics materials and the parts 1, 2, 110, 112, and 3 of the coupling described being also of thermoplastics material. The invention is not of course confined to pipe systems of thermoplastics materials nor to couplings made of thermoplastics materials. WHAT WE CLAIM IS:

1. A pipe coupling comprising two tubular parts each provided with a flange at one end, a clamping ring having an internal groove into which the flanges extend when the coupling is assembled with the two tubular parts disposed in end to end relationship with their flanges together, the coupling including an annular seal which seals each of said tubular parts with respect to the other when the coupling is assembled, and wherein each of said flanges, in axial section through the respective tubular part, on its side which is furthest from the other of said flanges, slopes outwardly

from the periphery of the tubular part towards said one end thereof, whereby when the coupling is assembled, and the clamping ring is tensioned circumferentially, the circumferential tension in the clamping ring produces a wedging action urging one flange into engagement, via the end face of its flange which faces towards the other flange, with the corresponding end face of the other flange, and wherein said internal groove in the clamping ring has side walls, defining the axial limits of the groove, which side walls, in axial section through the coupling, are radiused in the region of their free edges, whereby said side walls flare towards the edges of the groove, the arrangement being such that when the clamping ring is tensioned circumferentially, each said side wall of the groove engages the sloping side of the respective flange only along a continuous line of contact of the radiused part of the groove side wall with the sloping side of the respective flange.

2. A pipe coupling according to claim 1 wherein the annular seal is in the form of a resilient element which in axial section has the form of a channel, open on the radially inner side of the element and has a restricted mouth defined between two lips in the form of flanges extending towards each other from the side walls of said channel, the annular seal, in the assembled pipe coupling being accommodated between the bottom of the groove in the clamping ring and the peripheral surfaces of the flanges of the tubular parts with each lip engaging the peripheral surface of a respective one of the flanges and the junction between the flanges in the zone of the restricted mouth of the seal, whereby fluid under pressure within the tubular parts, escaping between the end faces of the flanges thereof will tend to inflate the seal and thus urge said lips even more firmly into sealing engagement with the peripheral surfaces of the flanges of the tubular parts.

3. A pipe coupling according to claim 2 wherein said annular seal is an elastomeric element.

4. A pipe coupling according to claim 3 wherein that end face of the flange of each tubular part which faces towards the flange of the other tubular part is provided with at least one groove extending thereacross from the radially inner to the radially outer edge of the flange, the or each said groove providing a passage for fluid within the tubular parts to the interior of the seal.

5. A pipe coupling according to any preceding claim wherein each of said two tubular parts comprises a first end portion provided with a respective said flange and a second end portion adapted for sealing connection with a respective pipe, each said flange being circular and defining a first axis of the respective pipe part, about which first axis the respective said flange is rotationally symmertical, whereby the two pipe parts can be connected, via their said flanges and said clamping ring, in any desired angular position with respect to the other about the coincident said first axes of the connected pipe parts, each said second end portion defining a respective second axis, which when a pipe is connected thereto cor- responds to the axis of the latter pipe, said second axis of each tubular part being inclined with respect to the first axis thereof, the arrangement being such that with said first end portions connected together via their flanges, with said first axes coincident, in any angular position of the pipe parts with respect to one another about said coincident first axes, said second axes of said tubular portions intersect at a point on the coincident said first axes or pass a common point on the coincident first axes at a distance small in relation to the diameter of said tubular portion.

6. A pipe coupling substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 of the accompanying drawings.

7. A pipe coupling substantially as hereinbefore described with reference to, and as shown in, Figures 5 and 6 of the accompanying drawings.

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