GB2278170A

GB2278170A - A threaded connection for pipes

Info

Publication number: GB2278170A
Application number: GB9407540A
Authority: GB
Inventors: Norbert Felder; Thomas Hanke; Arnold Barth
Original assignee: GKN Walterscheid GmbH; Walterscheid Rohrverbindungstechnik GmbH
Current assignee: Eaton Fluid Connectors GmbH; Walterscheid GmbH
Priority date: 1993-04-16
Filing date: 1994-04-15
Publication date: 1994-11-23
Anticipated expiration: 2014-04-15
Also published as: GB2278170B; ITMI940577A1; FR2704041B1; GB9407540D0; ITMI940577A0; FR2704041A1; IT1269919B

Abstract

A threaded connection comprises an externally threaded sleeve (1) having a through bore (10), an internally threaded nut (4) screwed onto the sleeve, a clamping ring (3) arranged between the nut and the sleeve to cut into and clamp the outer surface of a pipe (2), and a sealing ring (5) disposed between the end face of the pipe and a shoulder (11) of the sleeve. Different embodiments of sealing ring (5) are described in all of which the ring comprises a core (22), preferably of spring steel, and a coating (25) of a flexible sealing material such as natural or synthetic rubber or plastics or a lacquer. The coating (25) of the sealing ring is in sealing contact with the end face of the pipe and with the shoulder in the sleeve. <IMAGE>

Description

TITLE: A Threaded Connection For Pipes This invention relates to a threaded connection for sealingly connecting together a tube and pipe with another tube or pipe or with a further connector.

A threaded connection of this general type is disclosed in British patent 1 389 806 wherein there is described a connection comprising an externally threaded sleeve having a bore tapering conically towards the interior of said sleeve and merging into a stepped cylindrical bore, the diameter of the cylindrical bore immediately adjacent the tapered bore being larger than that of a pipe to be received therein and the shoulder of the step forming an annular abutment; a nut adapted to be engaged with said threaded sleeve and having a conically tapered bore merging into a cylindrical bore of larger diameter than that of the pipe; a sealing ring; and a clamping ring received between said sleeve and said nut and adapted to be fitted slidably over the pipe, said clamping ring having on its external surface at each end a cone-shaped formation each tapering in the same direction as a respective said conical bore in the nut and in the sleeve and having a bore with clamping formations thereon. In the construction disclosed in British patent 1 389 806 the sealing ring is located between the end face of the pipe and the shoulder of the step in the bore of the sleeve, the sealing ring comprising an elastomeric material mounted on an angle-section supporting ring.

A sealing ring of this type is suitable only for use in threaded connections wherein the end face of the pipe does not have to be supported firmly against an abutment during tightening of the nut on the sleeve. In threaded connections of this type, the pipe and the clamping ring are moved axially for a predetermined distance during tightening of the nut and part of the travel has to be accommodated by deformation of the sealing ring. During tightening of the nut onto the sleeve there is a risk of the sealing ring being overloaded and it is an object of the present invention to provide a threaded connection having a sealing ring which will provide improved sealing conditions.

In accordance with the invention there is provided a threaded connection comprising an externally threaded sleeve having a bore tapering conically towards the interior of said sleeve and merging into a stepped cylindrical bore, the diameter of the cylindrical bore immediately adjacent the tapered bore being larger than that of a pipe to be received therein, and the shoulder of the step forming an annular abutment; a nut adapted to be engaged with said threaded sleeve and having a conically tapered bore merging into a cylindrical bore of larger diameter than that of the pipe; a clamping ring received between said sleeve and said nut and adapted to be fitted slidably over the pipe, said clamping ring having on its external surface at each end a cone shaped formation each tapering in the same direction as a respective said conical bore in the nut and in the sleeve and having a bore with pipe clamping formations thereon; and a sealing ring arrangeable between the end face of the pipe and the shoulder of the step in the bore of the sleeve; wherein said sealing ring comprises a core and a coating thereon. the arrangement being that said coating of the sealing ring is in sealing contact with said end face of the pipe and with said step in the bore of the sleeve when the nut is tightened on the sleeve to clamp the pipe by means of said clamping ring.

Such a threaded connection in accordance with the invention has the advantage that the sealing ring is capable of accommodating large axial forces without its sealing effect being adversely affected. The thickness of the coating on the core of the sealing ring need only be such as to compensate for the normally occurring tolerances in respect of roughness and angularity of the end face of the pipe.

The core of the sealing ring may comprise a metal, especially steel such as spring steel or high grade steel, or may comprise a plastics material. The coating of the sealing ring conveniently comprises a flexible sealing material such as an elastomeric material which may be a natural or synthetic rubber or plastics material, or the coating may comprise a lacquer. Suitable elastomeric materials may comprise acrylonitrile butadiene rubber, fluorocaoutchouc, ethylene propylene diene caoutchouc, polyoxymethylene or polytetrafluoroethylene.

In order to increase the strength of the coating it may contain a percentage of fibre material such as glass fibres and/or carbon fibres. The coating may comprise a micro-encapsulated adhesive which is released when subjected to pressure after which the adhesive hardens. Conveniently the coating of the sealing ring has a thickness of between 0.02mm and 0.7mm.

The core of the sealing ring may comprise a planar annular member wherein the said coating covers at least the radially extending planar surfaces of said member.

Alternatively the core may comprise an annular member of generally U or V shaped cross-sectional configuration, the apex of said member being directed radially outwardly towards the wall of the cylindrical bore in the sleeve.

Alternatively again, the core may comprise an annular member of generally Cshaped cross sectional configuration, the apex of said member being directed axially towards the shoulder of the step in the bore of the sleeve. In these two embodiments the coating may cover at least those surfaces of said member which are in engagement with the wall of the cylindrical bore in the sleeve, with the shoulder of the step in the bore of the sleeve and with the end face of the pipe.

The coating may cover the entire surface of the core of the sealing ring.

The sealing ring is conveniently frictionally retainable within the said cylindrical bore of the threaded sleeve before the nut is tightened thereon.

Other features of the invention will become apparent from the following description given herein solely by way of example with reference to the accompanying drawings wherein: Figure 1 is a side elevation, partly in longitudinal cross-section, of a threaded connection in accordance with the invention; Figure 2 is a longitudinal cross-sectional view to an enlarged scale of the area X of Figure 1 illustrating a first embodiment of sealing ring; Figure 3 is a similar view to that of Figure 2 but showing a second embodiment of sealing ring; Figure 4 is a similar view to that of Figure 2 but showing a third embodiment of sealing ring; Figure 5 is a similar view to that of Figure 2 but showing a fourth embodiment of sealing ring; Figure 6 is a similar view to that of Figure 2 but showing a fifth embodiment of sealing ring; and Figure 7 is a similar view to that of Figure 2 but showing a sixth embodiment of sealing ring.

Referring to Figure 1 of the drawings there is shown a threaded connection in accordance with the invention. The connection includes a joint member comprising a sleeve 1 threaded externally at 12 and a through bore 10, a nut 4 threaded internally at 20 adapted to be screwed onto the sleeve 1, and a clamping ring 3 arranged between the nut 4 and the sleeve 1. The clamping ring 3 is slidably engageable over the end of a pipe 2 and has two oppositely directed conical surfaces 15 and 18. The sleeve 1 and the nut 4 are each provided with conical bores 7 and 21 co-directional respectively with the conical faces 15 and 18 of the clamping ring. Adjacent to the conical bore 7 in the sleeve 1 there is a cylindrical bore portion 9 having a diameter larger than that of the external diameter of the pipe 2. This bore portion 9 merges by a step or shoulder formation 11 into the through bore 10 of the threaded member. The conical bore 7 extends to an end face 8 of the sleeve 1.

The threaded member is provided with external flats 6 for engagement by a spanner and similarly, the nut 4 is also provided with external flats 19 for the same purpose.

The clamping ring 3 has an internal bore 17 of a diameter which is only slightly in excess of the external diameter of the pipe 2 and the bore of the clamping ring is provided with clamping or cutting formations 16 adapted for clamping and/or cutting into the material of the outer surface of the pipe 2 when the nut 4 is tightened on the sleeve 1.

As can be seen from Figure 1, the end face 14 of the pipe 2 is located in spaced relationship from the shoulder 11 with a sealing ring 5 arranged therebetween. In Figure 1, the nut 4 is illustrated as being screwed tightly onto the sleeve 1 whereby the cutting formations 16 of the clamping ring 3 have been caused to penetrate into the outer face of the pipe 2. It will be appreciated that tightening of the nut onto the sleeve causes the leading end of the clamping ring 3 to be wedged into radially inward engagement with the outer face 13 of the pipe 2 and during tightening of the nut 4 the clamping ring 3 is moved axially relative to the pipe when the pipe is in abutment with the sealing ring 5. To enable the clamping ring 3 to carry out the axial movement relative to the pipe 2 which is required to permit the clamping formations 16 to cut into the pipe it is necessary that the sealing ring 5 is of sufficient strength to provide a reaction to the axial force imparted thereto during tightening of the nut 4.

Six differing embodiments of sealing ring 5 are illustrated respectively in each of Figures 2 to 7 of the drawings and in accordance with the invention the sealing ring in each embodiment comprises a core 22 and a coating 25 thereon.

The core 22 may comprise a metal such as steel or may comprise a plastics material. The coating 25 conveniently comprises a flexible sealing material such as an elastomeric material which may be a natural or synthetic rubber or plastics material, or may be a lacquer.

In the first embodiment of sealing ring illustrated in Figure 2, the core 22 of the sealing ring comprises an annular planar disc-like member conveniently formed of steel. The radially extending planar surfaces 23 and 24 of the core 22 may be coated for example with an acrylonitrile butadiene rubber to a thickness of between 0.02mm and 0.7mm. Referring to Figure 2, the coating on the lefthand face 23 of the core is in sealing contact with the shoulder 11 of the step in the bore of the sleeve 1 whereas the coating on the righthand face 24 of the core is in sealing contact with the end face 14 of the pipe 2. During tightening of the nut 4 onto the sleeve 1, the axial movement of the pipe 2 will cause compression of the sealing ring and the establishment of a firm sealing contact.

The thickness of the coating 25 on the core 22 is sufficient to compensate for any unevenness or any angular offset in the end face 14 of the pipe 2. The sealing ring as a whole seals the annular gap between the end face 14 of the pipe and the shoulder 11 so that the medium flowing through the pipe and the bore of the sleeve does not enter into said gap.

Furthermore, since the entire end face of the pipe is covered by the sealing ring, any pressure applied by the medium flowing through the pipe will act only on the internal face of the pipe and on the sleeve so that the threaded connection between the members is unaffected.

In the second embodiment of sealing ring 5 illustrated in Figure 3, the core 22 is again provided in the form of an annular member having radially extending planar surfaces. However, in this second embodiment, the entire surface of the core 22 is covered by the coating 25 i.e. the coating extends fully across the radially extending planar surfaces of the core and also across the axially extending inner and outer surfaces of the core. The provision of the coating extending across the radially outer axial surface of the core enables the sealing ring to be frictionally retained within the cylindrical bore 9 of the sleeve 1 before the nut 4 is tightened onto the sleeve. After the nut has been tightened, the sealing ring 5 is compressed between the end face 14 of the pipe 2 and the shoulder 11 of the sleeve 1 in the same manner as described with reference to Figure 2.

In the third embodiment illustrated in Figure 4 of the drawings the sealing ring 5 is of inverted generally U-shaped cross-sectional form wherein the apex is directed radially outwardly towards the wall of the cylindrical bore 9 of the sleeve 1. Conveniently the core 22 is made of a spring steel material and is covered in its entirety by a coating 25. As will be seen from Figure 4, an end 26 of one of the limbs of the U-shaped ring abuts against the shoulder 11 of the sleeve 1 whereas the other limb end 27 abuts the end face 14 ot the pipe 2. A sealing ring constructed in accordance with this embodiment provides for greater axial resilience than the sealing rings of Figures 2 or 3 and is thus able to compensate for greater deviations in the linearity or angularity of the end face of the pipe. The sealing ring of Figure 4 is able to accommodate greater axial movement of the pipe relative to the sleeve during tightening of the nut than is the case with the sealing ring of Figures 2 or 3.

The fourth embodiment of sealing ring 5 illustrated in Figure 5 is somewhat similar to that of Figure 4 except that the cross-sectional configuration of the sealing ring 5 resembles an inverted V-shape rather than the inverted Ushape of Figure 4. In the Figure 5 embodiment, the core 22 may again be made of spring steel material with the coating 25 covering the entire surface of the core.

In similar manner to that hereinbefore described with reference to Figure 4, one limb end 26 of the sealing ring abuts the shoulder 11 of the step in the bore 9 of the sleeve 1 whereas the other limb end 27 of the sealing ring abuts the end face 14 of the pipe 2.

In the fifth embodiment illustrated in Figure 6 of the drawings, the sealing ring 5 is of generally C-shaped cross-sectional configuration with the apex thereof extending in an axial direction towards the shoulder 11 of the step in the bore 9 of the sleeve 1. As illustrated in Figure 6, the core 22 is covered in its entirety by a coating 25. The apex of the sealing ring abuts the shoulder whereas the outer ends 26 and 27 of the two limbs abut the end face 14 of the pipe 2 in spaced radial relationship.

The sixth embodiment of sealing ring 5 illustrated in Figure 7 is generally similar to that illustrated in Figure 6 except that the cross-sectional configuration of the sealing ring resembles a V-shape on its side rather than the C-shape of Figure 6. Again, the core 22 of the sealing ring of Figure 7 is covered in its entirety by a coating 25 and is arranged such that the apex abuts the shoulder 11 of the step in the bore 9 of the sleeve 1, and the ends 26 and 27 of the limbs abut the end face 14 of the pipe 2.

In either of the embodiments illustrated in Figures 6 and 7 the sealing ring may be reversed so that the apex thereof extends in an axial direction towards the end face 14 of the pipe 2 and the ends 26 and 27 of the limbs of the sealing ring abut the shoulder 11 of the step in the bore 9 of the sleeve 1.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A threaded connection comprising an externally threaded sleeve having a bore tapering conically towards the interior of said sleeve and merging into a stepped cylindrical bore, the diameter of the cylindrical bore immediately adjacent the tapered bore being larger than that of a pipe to be received therein, and the shoulder of the step forming an annular abutment; a nut adapted to be engaged with said threaded sleeve and having a conically tapered bore merging into a cylindrical bore of larger diameter than that of the pipe; a clamping ring received between said sleeve and said nut and adapted to be fitted slidably over the pipe, said clamping ring having on its external surface at each end a cone shaped formation each tapering in the same direction as a respective said conical bore in the nut and in the sleeve and having a bore with pipe clamping formations thereon; and a sealing ring arrangeable between the end face of the pipe and the shoulder of the step in the bore of the sleeve; wherein said sealing ring comprises a core and a coating thereon, the arrangement being that said coating of the sealing ring is in sealing contact with said end face of the pipe and with said step in the bore of the sleeve when the nut is tightened on the sleeve to clamp the pipe by means of said clamping ring.

2. A threaded connection as claimed in claim 1 wherein the core of the sealing ring comprises a metal or a plastics material.

3. A threaded connection as claimed in either one of claims 1 or 2 wherein the coating of the sealing ring comprises a flexible sealing material such as an elastomeric material comprising a natural or synthetic rubber or plastics material, or a lacquer.

4. A threaded connection as claimed in any one of claims 1 to 3 wherein the coating of the sealing ring contains fibre material such as glass and/or carbon fibres.

5. A threaded connection as claimed in any one of claims 1 to 4 wherein the coating of the sealing ring comprises a micro-encapsulated adhesive which is released when subjected to pressure.

6. A threaded connection as claimed in any one of claims 1 to 5 wherein the coating of the sealing ring has a thickness of between 0.02mm and 0.7mm.

7. A threaded connection as claimed in any one of claims 1 to 6 wherein the core of the sealing ring comprises a planar annular member and wherein the said coating covers at least the radially extending planar surfaces of said member.

8. A threaded connection as claimed in any one of claims 1 to 6 wherein the core of the sealing ring comprises an annular member of generally U or V shaped cross-sectional configuration, the apex of said member being directed radially outwardly towards the wall of the cylindrical bore in the sleeve.

9. A threaded connection as claimed in any one of claims 1 to 6 wherein the core of the sealing ring comprises an annular member of generally C-shaped cross-sectional configuration, the apex of said member being directed axially towards the shoulder of the step in the bore of the sleeve.

10. A threaded connection as claimed in either one of claims 8 or 9 wherein the coating covers at least those surfaces of said member which are in engagement with the wall of the cylindrical bore in the sleeve, with the shoulder of the step in the bore of the sleeve and with the end face of the pipe.

11. A threaded connection as claimed in any one of claims 7 to 10 wherein the coating covers the entire surface of the core of the sealing ring.

12. A threaded connection as claimed in any one of claims 1 to 11 wherein the sealing ring is frictionally retainable within the said cylindrical bore of the threaded sleeve before the nut is tightened thereon.

13. A threaded connection constructed and arranged substantially as hereinbefore described with reference to any of the accompanying drawings.

14. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.