GB2313888A

GB2313888A - Pipe coupling comprising coupling sleeve with sealing element

Info

Publication number: GB2313888A
Application number: GB9710957A
Authority: GB
Inventors: Robert James Pritchatt
Original assignee: Flex Seal Couplings Ltd
Current assignee: Flex Seal Couplings Ltd
Priority date: 1996-06-04
Filing date: 1997-05-29
Publication date: 1997-12-10
Anticipated expiration: 2017-05-29
Also published as: GB9710957D0; GB2313888B

Abstract

The rubber sealing element (10) is secured inside rigid outer sleeve (11) by means of at least one clip (15) at each end, each clip having in axial cross-section a barb (19) on the inner end of an inner limb (17) integral with an outer limb (16) on the outside of the sleeve (11) through a connecting portion (18), with the barb engaging behind a shoulder (20) facing inwardly in the sealing element (10), whereby an inserted pipe spigot (14) exerts localised forces on the inner limb (17) of the clip (15) causing the barb (19) to be urged towards the outer limb (16) and so grip the sealing element (10) firmly between the barb (19) and the outer sleeve (11). The clip (15) may be annular or a series of peripherally spaced clips provided; the clip is metal or plastics.

Description

PIPE COUPLINGS This invention relates to pipe couplings of the composite type in which a rubber sealing element is located inside an outer coupling sleeve of relatively greater rigidity, such as are used in pipe-jacking and where the force required to apply the couplings onto the pipe spigots is relatively high.

The rubber sealing element is frequently secured in the outer coupling sleeve by an adhesive (but mechanical fixing is also known), and initial interference between a pipe spigot and the sealing element can cause very high forces acting on the leading edge of the rubber element, especially when there is axial misalignment between the coupling and the pipe spigot, which forces can cause the rubber sealing element to peel away from the outer sleeve and result in a hydraulic failure of the resulting joint.

The object of the present invention is to provide means for overcoming this danger.

According to the present invention, a pipe coupling of the composite type referred to is provided with at least one clip at each end, the axial cross-section of each clip comprising an outer limb overlying the outside of the outer coupling sleeve, an inner limb extending inwardly of the rubber sealing element, an integral connecting portion between the limbs, and a barb at the inner end of the inner limb projecting towards the outer limb, the rubber sealing element having at each end an inwardly facing annular shoulder behind which the respective barb engages, and the inner limb of each clip section diverging from the outer limb in the direction away from the connecting portion, whereby the inner limb affords a lead-in for a pipe spigot.

Each end of the coupling may be provided with a plurality of clips as aforesaid spaced around the coupling, or each end may be provided with a single annular clip.

If there is any axial misalignment between the coupling and a pipe spigot to which the coupling is being fitted, the pipe spigot will exert localised forces on the inner limb ofthe clip (or clips), whereby the barb will be urged towards the outer limb (by expansion or deflection of the inner limb) and the sealing element will be gripped firmly between the barb and the outer sleeve.

The inside diameter of the clip at the inner end of the inner limb (or the distance between similar locations on a pair of diametrically opposite clips) is preferably slightly less than the outside diameter of a pipe spigot to which the coupling is to be fitted, whereby the barb will always be urged towards the outer limb (by expansion or deflection of the inner limb or limbs) and, consequently, the sealing element will always be gripped firmly all round to the outer sleeve as the coupling is pushed on to the pipe spigot or the pipe spigot is pushed into the coupling.

Each clip may be formed of stainless steel bent to shape or bent stainless steel strip clip material may have the connecting portion, inner limb and barb notched at equi-spaced intervals to enable the outer limb to be bent to conform closely to the outside of the outer coupling sleeve; while each annular clip may be formed by a length of extruded plastics section with the ends bonded together or merely abutted, and in the latter case the outer limb may be secured to the outside of the outer coupling sleeve by a clamping band, which may be located in a groove in the outer limb of the clip, e.g., between two circumferential ribs on the outer limb of the clip.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings (which are not to scale) in which: Figure 1 is a longitudinal section through one side of a pipe coupling in accordance with the invention; Figure 2 is an enlargement of the left hand end of Figure 1 showing the initial insertion of one spigot of a pipe; Figure 3 corresponds to Figure 2 but shows the pipe spigot pushed a little further into the coupling; Figure 4 corresponds to Figure 3 but shows the pipe spigot pushed more fully into the coupling; Figure 5 is an end view of a pipe coupling in accordance with the invention having a plurality of clips, spaced around it; Figure 6 is an end view of a pipe coupling in accordance with the invention having a single annular clip applied to it; Figure 7 is a fragmentary view of stainless steel clip material ready for applying to a coupling; Figure 8 is a fragmentary end view of a coupling with the clip material of Figure 7 applied to it; and Figure 9 is an enlargement of the left hand end of Figure 1 but showing a plastics clip secured by a band clamp.

The pipe coupling shown in Figure 1 comprises a rubber sealing element 10 located inside an outer coupling sleeve 11 of steel affording relatively greater rigidity, and the rubber sealing element 10 has at each end annular sealing lips 12, 13 to effect sealing with an inserted pipe spigot 14, as shown in Figure 4. This coupling of the composite type is provided, in accordance with the invention, with at least one clip 15 at each end, and the axial cross-section of each clip comprises an outer limb 16 overlying the outside of the outer coupling sleeve 11, an inner limb 17 extending inwardly ofthe rubber sealing element 10, an integral connecting portion 18 between the limbs, and a barb 19 at the inner end of the inner limb projecting towards the outer limb, the rubber sealing element 10 having at each end an inwardly facing annular shoulder 20 behind which the respective barb 19 engages, and the inner limb 17 of each clip 15 diverges from the outer limb 16 in the direction away from the connecting portion 18, whereby the inner limb affords a lead-in for a pipe spigot.

Each end of the coupling may be provided with a plurality of clips 15 as aforesaid spaced around the coupling (see Figure 5), or each end may be provided with a single annular clip 15 (see figure 6). The inside diameter D of the annular clip 15 at the inner end of the inner limb 17, or the distance D between similar locations on a pair of diametrically opposite clips 15, is preferably slightly less than the outside diameter of the pipe spigot 14 to which the coupling is to be fitted, whereby the barb 19 will always be urged towards the outer limb 16 upon initial pushing ofthe pipe spigot into the coupling (see Figures 2 and 3) by expansion or deflection of the inner limb or limbs, and, consequently, the sealing element 10 will always be gripped firmly all round to the outer sleeve 11 as the coupling is pushed on to the pipe spigot 14 or the pipe spigot is pushed into the coupling.

If there is any axial misalignment between the coupling and the pipe spigot to which the coupling is being fitted, the pipe spigot will exert localised forces on the inner limb 17 of the clip (or clips), whereby the barb will be urged even more towards the outer limb 16 and the sealing element 10 will be gripped more firmly between the barb (or barbs) 19 at that side until the pipe spigot and coupling become axially aligned.

Each of the single clips 15 (Figure 5) is formed of stainless steel bent to shape; alternatively, bent stainless steel strip clip material (see Figure 7) may have its connecting portion 18, inner limb 17 and barb 19 notched at equi-spaced intervals to enable the outer limb 16 to be bent to conform closely to the outside of the outer coupling sleeve 11.

Again, each annular clip 15 may be formed by a length of extruded plastics section with the ends 21 (see Figures 6 and 9) bonded together or merely abutted, and in the latter case the outer limb 16 is preferably secured to the outside ofthe outer coupling sleeve 11 by a clamping band 22, which is preferably located in a groove 23 in the outer limb 16 of the clip formed between two circumferential ribs 24 on the outer limb ofthe clip.

Claims

1. A pipe coupling of the composite type in which a rubber sealing element is located inside an outer coupling sleeve of relatively greater rigidity, characterized by at least one clip at each end, the axial cross-section of each clip comprising an outer limb overlying the outside of the outer coupling sleeve, an inner limb extending inwardly of the rubber sealing element, an integral connecting portion between the limbs, and a barb at the inner end of the inner limb projecting towards the outer limb, the rubber sealing element having at each end an inwardly facing annular shoulder behind which the respective barb engages, and the inner limb of each clip section diverging from the outer limb in the direction away from the connecting portion, whereby the inner limb affords a lead-in for a pipe spigot.

2. A pipe coupling as in Claim 1, characterized in that each end of the coupling is provided with a plurality of clips as aforesaid spaced around the coupling.

3. A pipe coupling as in Claim 1, characterized in that each end of the coupling is provided with a single annular clip.

4. A pipe coupling as in any one of Claims 1 to 3, characterized in that the inside diameter of the clip at the inner end of the inner limb or the distance between similar locations on a pair of diametrically opposite clips is slightly less than the outside diameter of a pipe spigot to which the coupling is to be fitted.

5. A pipe coupling as in Claim 2, characterized in that each clip is formed of stainless steel bent to shape.

6. A pipe coupling as in Claim 3, characterized in that bent stainless steel strip clip material has the connecting portion, inner limb and barb notched at equi-spaced intervals to enable the outer limb to be bent to conform closely to the outside of the outer coupling sleeve

7. A pipe coupling as in Claim 3, characterized in that each clip is formed by a length of extruded plastics section with the ends bonded together or merely abutted.

8. A pipe coupling as in Claim 7, characterized in that with the ends of the extruded plastics section merely abutted, the outer limb is secured to the outside of the outer coupling sleeve by a clamping band.

9. A pipe coupling as in Claim 8, characterized in that the clamping band is located in a groove in the outer limb of the clip.

10. A pipe coupling as in Claim 9, characterized in that the groove in the outer limb of the clip is formed between two circumferential ribs on the outer limb of the clip.

11. Pipe couplings of the composite type provided with clips substantially as hereinbefore described with reference to the accompanying drawings.