GREIFRING

Description

[0001] The present invention relates to a pipe coupling for providing a fluid-tight coupling to pipes, and especially plastic pipes, and in particular PE pipes. Numerous pipe couplings exist for coupling plastic pipes, for example, as disclosed in the applicant's earlier EP-A-1164325 and EP-A-1292792, and also disclosed in US 6 206 434 B1, WO-A-2012 / 149010 and WO-A-2013 / 041491.

[0002] These pipe couplings require, however, very high radial compression loads, and associated bolt torques, in order to crush gripper elements of the couplings against the periphery of the pipe sufficiently to prevent release of the pipes from the couplings under normal, operative axial loads.

[0003] The extent of these compressive loads is such as to require the use of an internal stiffening liner, typically formed of stainless steel of coated mild steel, within the pipe in order that the pipe can withstand the crush loading without collapsing.

[0004] Moreover, these existing pipe couplings usually require a compression seal, the efficiency of which is determined by the radial compression, and thus there are competing factors in requiring a predetermined radial compression to ensure optimal sealing of the compression seal, but requiring an often-higher radial compression in order to ensure sufficient grip on the pipe.

[0005] It is an aim of the present invention to provide a pipe coupling which enables operation with much lower compressive loading of pipes, and can allow in some embodiments for use without a stiffening liner.

[0006] In one aspect the present invention provides a gripper ring for a pipe connector or coupling according to claim 1.

[0007] Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which: Figure 1 illustrates a perspective view of a pipe coupling in accordance with a first embodiment of the present invention where fitted to a pipe end; Figure 2 illustrates a longitudinal sectional view of the pipe coupling of Figure 1 when located over the pipe end and before application of any radial, compressive loading of the pipe coupling; Figure 3 illustrates a longitudinal sectional view of the pipe coupling of Figure 1 when fitted to the pipe end and subjected to a predetermined compressive loading for a fluid-tight seal; Figure 4 illustrates a longitudinal sectional view of the pipe coupling of Figure 1 following application of an axial loading of the pipe relative to the pipe coupling; Figure 5 illustrates a fragmentary perspective view of the gripper of the gripper ring of the pipe coupling of Figure 1; Figure 6 illustrates an enlarged perspective view of one gripper element of the gripper ring of Figure 5; Figure 7 illustrates plots of the maximum axial load sustainable by pipe couplings having different insertion angles as a function of insertion depth; Figure 8 illustrates a longitudinal sectional view of a pipe coupling in accordance with a second embodiment of the present invention when located over the pipe end and before application of any radial, compressive loading of the pipe coupling; Figure 9 illustrates a longitudinal sectional view of the pipe coupling of Figure 8 when subjected to a predetermined compressive loading for a fluid-tight seal; Figure 10 illustrates a longitudinal sectional view of the pipe coupling of Figure 8 following application of an axial loading of the pipe relative to the pipe coupling; Figures 11(a) to (c) illustrate views of a carrier member and blade element of the pipe coupling of Figure 8;and Figure 12 illustrates a gripper ring as a modification of the pipe coupling of Figure 1.

[0008] Figures 1 to 5 illustrate a pipe coupling or connector in accordance with a first embodiment of the present invention.

[0009] The pipe coupling comprises an annular gripper ring 3 which receives a pipe P therewithin, and a clamp 7 which acts to apply a radially-inward compressive load on the gripper ring 3 in order to displace the gripper ring 3 against an external peripheral surface S of a wall W of the pipe P, as will be described in more detail hereinbelow.

[0010] In this embodiment the gripper ring 3 comprises a gripper 11 which is inserted into the external surface S of the pipe P when the gripper ring 3 is clamped to the pipe P by operation of the clamp 7, and a carrier 15 which supports the gripper 11 with a defined orient in relation to the external surface S of the pipe P.

[0011] In this embodiment the gripper 11 comprises a plurality of blade elements 17, which are arranged in circumferential relation and, when clamped to the pipe P by the clamp 7, are inserted into the external surface S of the pipe P, here cutting into the external surface S of the pipe P.

[0012] In this embodiment the blade elements 17 each have a main body section 17a by which the blade element 17 is supported with a predetermined orient in relation to the external surface S of the pipe P, an external edge section 17b by which the blade element 17 is displaced inwardly during operation of the clamp 7, and an internal edge section 17c which provides a blade 18 which is inserted into the external surface S of the pipe P, here cutting into the external surface S of the pipe P, in order to engage the pipe P.

[0013] In this embodiment the blade elements 17 are configured such that the blades 18 are inserted into the external surface S of the pipe P at a predetermined angle thereto.

[0014] In this embodiment the blades 18 are inclined in relation to the external surface S of the pipe P, as illustrated in Figure 2, such that the blades 18 each enclose an acute angle β with the external surface S of the pipe P rearwardly of the point of insertion of the blade 18 in relation to the distal end of the pipe P.

[0015] In this embodiment the insertion angle β is 65 degrees.

[0016] In one embodiment the insertion angle β is at least about 50 degrees.

[0017] In one embodiment the insertion angle β is at least about 55 degrees.

[0018] In one embodiment the insertion angle β is not greater than about 80 degrees.

[0019] Figure 7 shows the relationship of the maximum axial load which can be withstood by the pipe coupling, where the blade elements 17 are arranged in symmetrical relation, with insertion angles β of 50, 60, 70 and 80 degrees. As will be seen, for axial loads greater than about 10 kN, configuring the blades 18 to have an insertion angle β of between 60 and 70 degrees, optimally about 65 degrees, provides for substantially greater resistance to axial loads for any given insertion depth.

[0020] In this embodiment the blade elements 17 are inserted a predetermined depth d into the wall W of the pipe P, as illustrated in Figure 3, with the insertion depth d being less than 10% of the thickness of the wall W of the pipe P. By way of example, for a 630 mm SDR17 pipe, the blade elements 17 could be inserted 3.5 mm into the wall W of the pipe P.

[0021] In this embodiment the blades 18 each comprise first and second spaced blade sections 18a, b, which allow the blade 18 to conform the outer peripheral surface S of the pipe P when displaced inwardly by operation of the clamp 7.

[0022] In this embodiment the blade sections 18a, b are coupled by a web section 19, here of V shape, which supports the blade sections 18a, b in the axial direction and enables relative movement of the blade sections 18a, b in the radial direction, such as to promote preferential movement in relation to the web section 19 during compression of the gripper 11 and thereby promote uniform displacement of the blade elements 17.

[0023] In this embodiment the blades 18 together define an inner opening 21 which has a diameter greater than the outer diameter of the pipe P, as illustrated in Figure 2, thereby facilitating fitting of the pipe coupling to the pipe P, especially when the pipe P is out of round.

[0024] In this embodiment the diameter of the inner opening 21 is such as to allow for the pipe P being 3% out of round from the nominal outer diameter, optionally being 5% out of round.

[0025] In one embodiment the blades 18 form a substantially-continuous annular ring.

[0026] In another embodiment the blades 18 are located at spaced locations about the gripper ring 3, with the arrangement and spacing therebetween being determined by the operational loading of the pipe P. In one embodiment the blades 18 have a space therebetween of at least half the width of the blades 18, optionally at least the width of the blades 18, and optionally at least twice the width of the blades 18.

[0027] In this embodiment the blade elements 17 are formed of sheet material, here a spring stainless steel.

[0028] In an alternative embodiment the blade elements 17 could be formed of a coated mild steel.

[0029] In one embodiment at least the inner edge sections 17c of the blade elements 17 are formed of sheet material.

[0030] In this embodiment the gripper 11 is formed from a single sheet, here by a stamping operation, but could alternatively be formed by other cutting and bending operations, with adjacent ones of the blade elements 17 being interconnected by web elements 23, here in the form of strips.

[0031] In this embodiment the web elements 23 comprise sections 23a, b which are inclined in relation to the radial direction, such as to promote preferential bending of the web elements 23 during compression of the gripper 11 and thereby promote uniform displacement of the blade elements 17.

[0032] In an alternative embodiment the blade elements 17 could be formed as separate elements which are not interconnected.

[0033] In this embodiment, as particularly illustrated in Figure 6, the blade elements 17 comprise at least one, here first and second guides 25, which are arranged in relation to the edge of the blade 18, such that, on insertion of the blade element 17 to the required extent into the wall W of the pipe P, the guides 25 abut the external surface S of the pipe P, thereby providing a clear visual indication to the operator when the clamp 7 is applied to the required extent.

[0034] In this embodiment the clamp 7 comprises an annular body 27 which includes a recess 29 which captively receives the gripper ring 3, in this embodiment being defined by first and second flange members 31, 33 which are spaced in axial relation.

[0035] In this embodiment the carrier 15 comprises at least one, here first and second support members 37a, b, which act to sandwich the gripper 11 therebetween.

[0036] In this embodiment the support members 37a, b each have a support surface 39, and the support surfaces 39 receive the main bodies 17a of the blade elements 17 therebetween, such as to orient the blade elements 17 at the predetermined insertion angle β.

[0037] As discussed above, the pipe coupling of the present invention operates by displacement of the blade elements 17 by application of a radial load F1, such that the blade elements 17 are inserted into the wall W of the pipe P to a predetermined extent, which does not require the maintenance of a high crush loading on the pipe P.

[0038] In use, the pipe P will be subjected to an axial load F2, which the pipe coupling is configured to withstand. With an increasing axial load F2 below the rated load for the pipe coupling, the blades 18 of the blade elements 17 are configured to pivot and elastically deform, as illustrated in Figure 4 where the blade 18 pivots through an angle θ in relation to the insertion angle β, allowing the pipe coupling to withstand a significant axial load F2, and to return to the original configuration on release of the axial load F2.

[0039] In this embodiment the clamp 7 comprises a ring clamp and the clamp body 27 has open ends 53, with a fixing 55, here a bolt arrangement, connecting the open ends 53 and being operative to provide for closure of the annular body 27 and thus clamping of the gripper ring 3.

[0040] In an alternative embodiment the clamp 7 could be a multi-segment clamp comprising a plurality of clamp body parts 27 with adjacent open ends 53, and a plurality of fixings 55 which interconnect the same.

[0041] The pipe coupling further comprises a coupling member 61 which is connected to the clamp 7 and provides for connection to a pipe component.

[0042] In this embodiment the coupling member 61 comprises a flange adaptor, but could be any kind of pipe component.

[0043] The pipe coupling further comprises an annular seal 63 which maintains a fluid-tight seal with the external surface of the pipe P. In this embodiment the coupling member 61 includes an annular recess 65, which receives the seal 63.

[0044] In this embodiment the seal 63 is a lip seal, which utilizes the fluid pressure to maintain the seal, with an increasing sealing force being applied with increasing fluid pressure. As noted above, existing pipe couplings necessitate the use of a compression seal, which relies on the compression force to achieve sealing, and does not provide for an increasing sealing force with increasing fluid pressure.

[0045] Figures 8 to 11 illustrate a pipe coupling in accordance with a second embodiment of the present invention.

[0046] The pipe coupling of this embodiment is similar to the pipe coupling of the first-described embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail, with like parts being designated by like reference signs.

[0047] In this embodiment the blade elements 17 are separate elements, and omit the formed external edge section 17b.

[0048] In this embodiment the carrier 15 comprises a plurality of recesses 75, which each provide the support surfaces 39, which support the main body sections 17a of the respective blade elements 17.

[0049] In this embodiment the carrier 15 comprises a plurality of carrier members 77 which are disposed in the recess 29 in the annular body 27 of the clamp 7.

[0050] In this embodiment the carrier members 77 each having oppositely-directed, axial faces 79a, b which engage the recess 29 in the annular body 27 of the clamp 7, oppositely-directed circumferential faces 83a, b, and oppositely-directed, inner and outer radial faces 84a, b.

[0051] In this embodiment the carrier members 77 are interconnected, here interengaged, as an annulus which extends around the external surface S of the wall W of the pipe P.

[0052] In this embodiment the carrier members 77 each have first and second engagement elements 85a, b, here male and female elements, by which adjacent ones of the carrier members 77 are interengaged.

[0053] In this embodiment the engagement elements 85a, b are disposed to the circumferential faces 83a, b of the carrier member 77.

[0054] In this embodiment the recess 29 in the annular body 27 of the clamp 7 has first and second opposed, axial faces 87a, b and an inner radial face 88, and the axial faces 87a, b of the annular body 27 of the clamp 7 and the axial faces 79a, b of the carrier members 77 are of corresponding tapered or wedge shape, maintaining the carrier members 77 in a fixed orientation in relation to the pipe P during the application of a radial load F1 to the clamp 7.

[0055] In this embodiment the recess 29 in the annular body 27 of the clamp 7 and the carrier members 77 are configured to allow for limited radial displacement of the carrier members 77 in relation to clamp 7 during the application of a radial load F1 to the clamp 7, as will be described further hereinbelow.

[0056] In this embodiment one, first faces 79a, 87a of the recess 29 and the carrier members 77 extend in a plane which is substantially perpendicular to the external surface S of the pipe P, and the other, second faces 79b, 87b of the recess 29 and the carrier members 77 are inclined outwardly in relation to the one, first faces 79a, 87a of the recess 29 and the carrier members 77.

[0057] In this embodiment at least one of the axial faces 79a, b of the carrier members 77 includes at least one, here a plurality of first deformable elements 91, which are configured to maintain the relative orientation of the carrier members 77 but are deformable on application of a radial load F1 to the clamp 7, so as to enable the carrier members 77 to be displaced, to a limited extent, further into the recess 29 in the annular body 27 of the clamp 7.

[0058] In this embodiment the first deformable elements 91 comprise an array of projections.

[0059] In this embodiment the carrier members 77 each further include at least one, here a plurality of second deformable elements 93, which engage the inner radial face 88 of the recess 29 in the annular body 27 of the clamp 7 and, with the application of increasing radial load F1 during tightening of the clamp 7, can be deformed.

[0060] This configuration allows the pipe coupling to accommodate the pipe P when out-of-round or having some ovality, in that the second deformable elements 93 of ones of the carrier members 77 which first engage the external surface S of the pipe P can be displaced outwardly in relation to the clamp 7 while the clamp 7 is continued to be tightened, until the clamp 7 is tightened sufficiently that the inner radial faces 84b of the carrier members 77 abut the external surface S of the wall of the pipe P.

[0061] Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

[0062] In one modification, as illustrated in Figure 12, the pipe coupling could comprise a plurality of grippers 11a, b which are arranged in spaced axial relation, here stacked relation, such as to provide for increased resistance to axial loading.

Claims

1. A gripper ring (3) for a pipe connector or coupling which receives a pipe (P) therewithin, wherein the gripper ring (3) comprises a gripper (11) which includes a plurality of blade elements (17) which are displaceable between a first, pipe-receiving configuration in which the pipe (P) is receivable within the at least one gripper ring (3) and a second, inwardly-displaced inserted configuration in which the blade elements (17) are insertable into an external wall (W) of the pipe (P); wherein the blade elements (17) each comprise a main body section (17a) and an internal blade edge section (17c) which includes at least one blade edge (18) which is insertable into the external wall (W) of the pipe (P), with at least the blade edge sections (17c) being formed of sheet material, wherein adjacent ones of the blade elements (17) are interconnected by webs (23) or the blade elements (17) are separate elements which are not interconnected.

2. A pipe connector or coupling for providing a coupling to a pipe (P), the pipe coupling comprising: the gripper ring (3) of claim 1; and a clamp (7) for applying a radially-inward compressive load on the at least one gripper ring (3) to displace the blade elements (17) thereof from the pipe-receiving configuration to the inserted configuration.

3. The gripper ring (3) of claim 1 or the pipe coupling of claim 2, wherein the at least one gripper ring (3) comprises a carrier (15) which supports the gripper (11) with a defined orientation.

4. The gripper ring (3) of claim 1 or 3 or the pipe coupling of claim 2, wherein: (I) the blade elements (17) each have an external edge section (17b) by which the blade element (17) is displaced inwardly during operation of the clamp (7); (II) the internal blade edge section (17c) has a predetermined angle (β) in relation to the longitudinal axis of the pipe coupling, such that the blade edge sections (17c) are insertable into the external wall (W) of the pipe (P) at the predetermined angle (β) thereto; (III) the blade elements (17) together form a substantially-continuous annular ring; (IV) the blade elements (17) are located at spaced circumferential locations about the at least one gripper ring (3); (V) the blade elements (17) together define an inner opening (21) which has a diameter greater than an outer diameter of the external wall (W) of the pipe (P) prior to application of the clamp (7), and the diameter of the inner opening (21) allows the pipe (P) to be at least 3% out of round from a nominal outer diameter of the pipe (P); (VI) the blade elements (17) are insertable to a depth (d) into the external wall (W) of the pipe (P), with the insertion depth (d) being less than 10% of the thickness of the external wall (W) of the pipe (P); (VII) the blade elements (17) are formed of sheet material; (VIII) the blade elements (17) are separate elements which are not interconnected; and / or (IX) the blade elements (17) each comprise at least one insertion depth guide (25) which is disposed in relation to the blade edge (18), such that, on insertion of the blade edge (18) to a required extent into the external wall (W) of the pipe (P), the at least one guide (25) abuts the external wall (W) of the pipe (P).

5. The gripper ring (3) or the pipe coupling of claim 4, wherein the gripper (11) is formed from a single sheet with adjacent ones of the blade elements (17) being interconnected by webs (23), optionally in the form of strips.

6. The gripper ring (3) or the pipe coupling of claim 5, wherein the webs (23) are inclined so as to promote preferential bending of the webs (23) during application of the clamp (7).

7. The gripper ring (3) of any of claims 1, 3 to 6 or the pipe coupling of any of claims 2, 3 to 6, wherein: (I) the gripper (11) is formed of stainless steel or a coated mild steel; (II) the at least one gripper ring (3) is formed as a single, integral part; (III) the at least one gripper ring (3) is formed of stainless steel or a coated mild steel; (IV) the clamp (7) comprises an annular body (27) which includes at least one recess (29) which captively receives the at least one gripper ring (3), the at least one recess (29) is defined by flange members (31, 33) which are spaced in longitudinal relation, the at least one gripper ring (3) has an outwardly-facing support surface (79b) which is inclined or tapered in relation to the longitudinal axis of the pipe coupling, and the at least one recess (29) in the clamp (7) includes an inwardly-facing support surface (87b), which supports the support surface (79b) of the at least one gripper ring (3) and is inclined or tapered to the longitudinal axis of the pipe coupling, tapering radially inwardly in a direction away from the distal end of the pipe (P); and / or (V) the at least one gripper ring (3) comprises a carrier (15) which comprises at least one carrier member (77) which supports the gripper (11).

8. The pipe coupling of any of claims 3 to 7, wherein the clamp (7) has a recess (29) which receives the carrier (15), the recess (29) having first and second opposed, axial faces (87a, b) and an inner radial face (88), and the carrier members (77) each having oppositely-directed, first and second side axial faces (79a, b) which engage the axial faces (87a, b) of the recess (29) in the clamp (7), oppositely-directed, first and second end circumferential faces (83a, b) and oppositely-directed, inner and outer radial faces (84a, b), with the axial faces (87a, b) of the recess (29) in the clamp (7) and the axial faces (79a, b) of the carrier members (77) being of corresponding tapered or wedge shape, maintaining the carrier members (77) in a fixed orientation in relation to the pipe (P) during application of the clamp (7), the recess (29) in the clamp (7) and the carrier members (77) being configured to allow for outward radial displacement of the carrier members (77) in relation to clamp (7) during the application of the clamp (7).

9. The pipe coupling of any of claims 2 or 3 to 8, wherein: (I) the pipe coupling comprises a plurality of grippers (11a, b) which are arranged in spaced axial relation; and / or (II) the pipe coupling comprises a plurality of gripper rings (3) which are arranged in spaced axial relation.

10. The pipe coupling of any of claims 2 or 3 to 9, further comprising: (I) a coupling member (61) which is connected to the clamp (7) and provides for connection to a pipe component; and / or (II) an annular seal (63) for maintaining a fluid-tight seal with the external wall (W) of the pipe (P).