GB2131904A - Pipe coupling - Google Patents

Abstract

A pipe coupling for joining, end to end, flanges ends of two pipes (1, 2) each having an internally and externally conical end flange (7, 8) includes a profiled clamp fitting (3) which engages over the flanges (7, 8) and can be tightened, and a sealing ring (6) which lies against front surfaces of the flanges (7, 8) facing towards one another. In order to avoid radial displacement of the ends of the pipes (1, 2) to be joined and of the sealing ring (6) a ring (4) is included having substantially radially inwardly projecting shoulders (19, 20) which project between the radially outer edge portions (9, 10) of the front surfaces of the flanges (7, 8) facing towards towards one another, and which lie against those edge portions (9, 10). This ring (4) has axial end portions (15, 16) which lie against the peripheral edges (17, 18) of the flanges (7, 8). <IMAGE>

Description

SPECIFICATION Pipe coupling This invention relates to a pipe coupling joining, end to end, flanged ends oftwo pipes each having an internally and externally end conical flange, which coupling includes a releasabiytightenable profiled clamp fitting engageable over the end flanges, when the pipes are located end to end, and a sealing ring locatable to lie againstfrontsurfaces of the end flanges facing towards one another.

In a known pipe coupling ofthistype there is a radial clearance between the peripheral edges of the flanges atthe ends of the pipes and the bottom of the groove, generallytrapezoidal in axial cross-section, which is formed inside the profiled clamp fitting. The purpose ofthis radial clearance isto enable the clamp fining to be retightened if necessary. The effect ofthis radial clearance isthat radial compressiveforces acting from outside or bending forces acting on the pipes cause the ends of the pipes to shift radially relative to one another, so thatthejoin can no longer withstand a fairly high internal fluid pressure and becomes leaky.

In addition the material of the sea ling ring cannot yield radially outwards or inwards from the region between the flanges during the tightening process. This similarly impairs the sealing action and also the flow offluid in the region ofthe join, because ofthe sealing ring material projecting radially inwards.

There is thus a need for a generally improved pipe coupling which will withstand strongerforces.

According to the invention there is provided a pipe coupling forjoining, end to end, flanged ends of two pipes each having an internally and externally conical end flange, which coupling includes a releasably tightenable profiled clamp fitting engageable overthe end flanges, when the pipes are located end to end, a sealing ring locatable to lie against front surfaces of the end flanges facing towards one another, and a first retaining ring having substantially radially inwardly projecting shoulders, which, in operation ofthe coupling, project between the radially outer edge portions ofthefrontsurfaces of the end flanges when the latter are facing towards one another, and lie against said radially outer edge portions ofthe end fla nges, the fi rst reta i n ing ring having axial end portions which, in operation ofthe coupling, lie against the peripheral edges of the end flanges.

The first retaining ring securesthe ends of the pipes radially in position, so that they cannot shift radially relative to one another and acts as a spacer between the ends of the pipes or flanges, so that when the clamp fitting is tightened the sealing excessively in an axial direction. In addition the first retaining ring prevents the sealing material from yielding radially outwards.

The shoulders may be in the form of projections which are pressed outofthe ring material afterthe formation of incisions. The construction is particularly simple when a retaining ring made of metal is used.

The retaining ring may have a gap in the peripheral direction so as be biased into contact with the peripheral edges ofthe end flanges. In this way diameter tolerances in the flanges and in the ring are compensated for. Furthermore the arrangement of the sealing ring in the retaining ring surrounding it is therebyfacilitated. In the tightening process the conical front surfaces of the flanges facing towards one another, acting through the shoulders ofthe radially outer ring, then positively ensure that the first retaining ring is drawn radially inwards and thus held together.

Asecond retaining ring may be provided having shoulders, projecting substantially radially outwards at its edges, locatable to extend between the radially inner edge portions ofthefrontsurfaces of the end flanges which facetowards one another, for lying against said inner edge portions, and the internal diameter of the second retaining ring may be equal to that of the pipes to be joined. This second retaining ring is also responsible for centring and axially securing the ends of the pipes, and additionally prevents the material of the sealing ring from yielding radially inwards into the stream of fluid.Instead, the second ringensuresthatthereisasmoothtransition without any step between the ends of the pipes to be joined, so that the passage offluid through the joined pipes is not impeded.

Fora better understanding ofthe present invention, and to show how the same may be carried into effect, reference will now be made, by way of example to the accompanying drawings, in which:~ Figure lisa perspective view of an arrangement of two pipes joined by a coupling according to the invention and Figure 2 is part of an axial section through the Figure 1 arrangement, in a perspective view.

The arrangement illustrated comprises two pipes and 2, a profiled clamp fitting 3, a radially outerfirst retaining ring 4, a radially inner second retaining ring 5 and a sealing ring 6 located between them.

The pipes 1 and 2 are made of metal and are flanged round at the ends facing towards one another, thus forming internally and externally conical ortapered end flanges 7 and 8, the radially outer end portions 9 and 10 of which are at a smaller axial spacing than the radially inner end portions 11 and 12.

The profiled clamp fitting 3 comprises two half fittings with a groove oftrapezoidal cross-section on the inside. The angle of inclination of the flanges 13 and 14 of the clamp fitting matches that of the flanges 7 and 8 on the inside. In the tightened state of the fitting 3the internal diameter ofthe bottom of the groove therein is largerthan the external diameter of the ring 4, and the internal diameter of the flanges 13 and 14 is largerthan the external diameter ofthe pipes 1 and 2.

The ring 4 extends axially of the pipes 1 and 2 and has edge portions 15 and 16 Iying againstthe respective peripheral edges 17 and 18 of the flanges 7 and 8. The ring 4similarly has shoulders 19 and 20 which lie against the front faces of the flanges 7 and 8 (facing towards one another) in the region of the end portions 9 and 10.Theshoulders 19 and 20 are pressed radially inwards out of the ring material after the formation of incisions 21 and 22, which extend right through in a radial direction and are formed at equal intervals in a peripheral direction.

The ring 4further has a gap in the peripheral direction, in the form of an axially continuous slot. The ring is therefore substantially C-shaped. It is made of resilient material so that it can spring in a radial direction. In the relaxed state of the ring 4 its internal diameter in the region ofthe edge portions 15 and 16 is somewhat smallerthan the external diameter of the flanges 7 and 8, so that in the fitted state the ring lies against the peripheral edges 17 and 18 of the flanges 7 and 8 under spring bias and thus compensates for tolerances in diameter.

The inner ring 5 is closed throughout in the peripheral direction, and is provided at its edges with shoulders 23 and 24 projecting substantially radially inwards in the form of flanges running round it. The flanges 23 and 24 are inclined to the axial direction at the same angle as the flanges 7 and 8, and lie against the radially inner end portions 11 and 12 of the flanges 7 and 8. The internal diameter of the ring 5 is equal to that of the pipes 1 and 2.

The sealing ring 6 has saw-tooth shaped sealing lips 25 and 26 running round it and lying againstthefront faces oftheflanges 7 and 8 which face one another.

The ring 6 is also in contact with the rings4and 5.

To assemble the arrangementthe rings 4,5 and 6 mayfirst be premounted and then brought into engagement and into contacttogetherwith one pipe flange 7 as shown in Figure 2. The flange 8 on the second pipe 2 is then inserted in the ring 4 or in its edge portion 16, so that it lies against the shoulders 20 and the rings Sand 6. Finally the profiled clamp fitting 3 is placed around the flanges 7 and 8 and tightened by means of screws 27 and 28. In the process the flanges 7 and 8 are placed firmly againstthe shoulders 19 and 20 at one side and the shoulders 23 and 24 at the other.

Owing to the inclination ofthe flanges 7 and 8 relative to the longitudinal axis ofthe pipes 1 and 2, the shoulders 19 and 20 ofthe ring 4 and thus the ring 4 itself are drawn together radially inwards, so that the end portions 15and 16 ofthe ring 4 lie firmly against the peripheral edges 17 and 18, although its external diameter is smaller than the internal diameter of the bottom ofthe groove in the clamp fitting 3.

The ring 5 is similarly centred by the flanges 7 and 8, ortheflanges 7 and 8 and the rings 4 and 5 centre one another mutually, so that the pipes 1 and 2 necessarily take up a coaxial position relative to one another and therefore withstand very strong fluid pressure forces on the one hand and radially external forces on the other, without shifting radially relative to one another.

The rings 4 and 5 at the same time act as spacers between the flanges 7 and 8, to prevent the sealing ring 6from being exposed to an excessively high axial pressure when the clamp fitting 3 is tightened. The rings 4 and 5 likewise limit the deformation ofthe sealing ring 6 in a radial direction, since together with the flanges 7 and 8 they enclose the ring 6 on all sides.

Modifications ofthe example illustrated come within the scope ofthe invention. Thus instead of having the incisions 21,22 extending radially and in the peripheral direction of the ring 4, with the shoulders pressed radially inwards adjacent those incisions, axial incisions may be formed in the edges ofthe ring 4, and alternate lugs located between those axial incisions may be bent radially inwards to form the shoulders 19 and 20. Alternatively, the shoulders 19 and 20 may be intheform of ribs running round on the inside ofthe ring 4. Instead of an axial slot forming the gap in the ring 4, a slot inclined to the axial direction may be provided. Then the ends of the ring 4 with a gap in itmayequallyengage in or overlap one another. The flanges 7 and 8 may alternatively be welded to the ends of the pipes or cast integrallywith the pipe, e.g. made of plastics. The material of all the rings, pipes and clamp fitting may be plastics.

However, metal is the preferred material apart from the sealing ring.

Claims (6)

1. A pipe coupling for joining, end to end, flanged ends oftwo pipes each having an internally and externally conical end flange, which coupling includes a releasablytightenable profiled clamp fitting engageable overthe end flanges, where the pipes are located end to end, a sealing ring locatable to lie againstfront surfaces of the end flanges facing towards one another, and a first retaining ring having substantially radially inwardly projecting shoulders, which, in operation of the coupling, project between the radially outer edge portions ofthefront surfaces ofthe end flanges when the latter are facing towards one another, and lie against said radially outer portions of the end flanges, the first retaining ring having axial end portions which, in operation of the coupling, lie against the peripheral edges of the end flanges.

2. A coupling according to claim 1 wherein the shoulders on the first retaining ring are in the form of projections, which are?ressed out ofthe ring material aftertheformation of incisions.

3. A coupling according to claim 1 or claim 2, wherein the first retaining ring has a gap in the peripheral direction and so as to be biassed into contactwiththe peripheral edgesoftheendflanges.

4. A coupling according to any one of claims 1 to 3, including a second retaining ring having shoulders, projecting substantially radially outwardly at its edges, locatable to extend between the radially inner edge portionsofthefrontsurfacesofthe end flanges whenfacing towards one another,for lying against said inner edge portions of the end flanges, the internal diameterofthe second retaining ring being substantially equal to the internal diameter of the pipes to be joined.

5. A coupling according to claim 4, wherein the sealing ring is locatable between the first and second retaining rings and the two end flanges.

6. A pipe coupling substantially as hereinbefore described with referenceto the accompanying drawings.