GB2097880A

GB2097880A - Improvements in pipe joints

Info

Publication number: GB2097880A
Application number: GB8113617A
Authority: GB
Original assignee: WHITEFIELD SYSTEMS HOLDINGS LT
Current assignee: WHITEFIELD SYSTEMS HOLDINGS LT
Priority date: 1981-05-02
Filing date: 1981-05-02
Publication date: 1982-11-10

Abstract

A pipe joint comprises a sealing ring (19) which is clamped between collars (13, 14) on the pipe ends by a split clamp ring (12) whose tapered internal surfaces (17, 18) engage resilient rings (23, 24) disposed between these surfaces and the collars. Yielding of the resilient rings (23, 24) ensures that the forwardly projecting spigots (20, 21), forming the pipe ends proper about which the sealing ring (19) is seated, are not brought into abutment with one another before the clamp ring (12) is fully tightened. This ensures a proper seal and reduces the risk of fracture of the clamp ring. <IMAGE>

Description

SPECIFICATION Improvements in pipe joints The present invention relates to pipe joints in which adjoining pipe ends are coupled together by a clamp ring.

in a known joint of this kind, the pipe ends are provided with external collars whose tapered rear faces are engaged by tapered internal walls of a split clamp ring. The wedging action of these tapered surfaces as the clamp ring is tightened about the collars causes a resilient sealing ring disposed between the collars to be axially compressed to ensure a fluid-tight seal at the joint. The sealing ring is seated about spigots projecting axially from the collars and forming the pipe ends proper. Normally these spigots remain slightly spaced apart when the clamp ring is fully tightened. It has been found that occasionally the spigots come into metai-to-metal contact before the clamp ring is fully tightened and the usual effect of this is that the clamp ring breaks or the joint leaks.

A pipe joint according to the invention comprises external collars on the adjoining pipe ends, projecting spigots on the collars, the spigots forming the pipe ends proper, a resilient sealing ring disposed between the collars and about the spigots, a split clamp ring disposed about the collars and the sealing ring and having opposed internal annular tapered faces and resilient means disposed between each annular tapered face and the confronting rear face of the respective collar, such that, on tightening the clamp ring, the spigots come into direct axial abutment with one another before the clamp is fully tightened, and the resilient means yields upon completion of the clamp ring tightening.

Each resilient means can comprise or consist of a resilient ring. If it consists of a resilient ring, it is directly engaged by the internal tapered face of the clamp ring. Alternatively, a loose back-up ring can be disposed between the tapered face and the resilient ring.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a fragmentary sectional view of a known pipe joint, Fig. 2 is a similar view of a first embodiment of pipe joint according to the invention, and Fig. 3 is a similar view of a second embodiment of the invention.

Fig. 1 shows a known pipe coupling in which two pipes 10, 1 1 are joined together by means including a clamp ring 12. The pipe ends have external collars 13, 14 whose annular rear faces 15, 16 are conically tapered. The clamp ring 12 is of somewhat channel-like cross section and its internal annular faces 17, 18 are complementarily conically tapered and engage the tapered faces 1 5, 1 6 of the collars. A resilient sealing ring 19 is disposed between the collars 13, 14 and is received on spigots 20, 21, which project axially towards one another from the collars 13, 14 and which form the pipe ends proper.

The clamp ring 12 is a split ring so that it can be placed around the collars 13, 14 as shown and then tightened. The wedging action at the tapered faces 15,17 and 16,18 urges the collars 13,14 axially towards one another to compress the sealing ring 19. The spigots 20, 21 remain slightly spaced apart, as shown and the sealing ring 19 effects the fluid-tight seal. An internal rib 22 in the clamp ring 12 engages the sealing ring 19 to prevent the latter from bulging outwardly under the pressure to be sealed.

Due to manufacturing inaccuracies, it may happen that the spigots 20, 21 will come into metal-to-metal contact before the clamp ring is fully tightened. If this should happen, the clamp ring may fracture, and even if it does not break, the seal may leak.

In Figs. 2 and 3, parts like those of Fig. 1 have the same reference numerals.

In the embodiment of the invention shown in Fig. 2, resilient rings 23, 24 are disposed between the internal tapered faces 17, 18 on the clamp ring 12 and the confronting annular rear faces 25, 26 on the collars 13, 14. The spigots 20, 21 are brought into axial abutment as shown before the clamp ring 12 is fully tightened. Upon continued tightening of the clamp ring, the resilient rings 23, 24 yield, thereby avoiding fracture of the clamp ring. The resilient rings 23, 24 also act as back-up sealing rings to help maintain the fluid seal.

In the embodiment of Fig. 3, the resilient rings 33, 34 are relatively flat and wedge-section backup rings 31,32 are disposed between the internal tapered surfaces 1 7, 1 8 on the clamp ring 12 and the collars 13,14.

The clamp ring 12 will usually be in two halves suitably bolted together. It may be cast from a metal, such as aluminium, but it is conceivable to mould them from a plastics material, such as nylon. The spigots 20, 21 are preferably formed integrally with the collars 1 3, 14 and welded to the ends of the pipes 10, 11. When the pipes are made of stainless steel, the collars are likewise of stainless steel. In an alternative method of manufacture, the collars are slipped onto the pipe ends and are welded in place, the spigots then being formed by the pipe ends themselves. The sealing ring 19 and the resilient rings 23, 24, 33, 34 are preferably of rubber. The resilient rings can be stretched over the collars to get them in place but the back-up rings 31, 32 of the Fig. 3 embodiment are preferably slipped onto the pipes before the collars are welded in place. Otherwise the back-up rings would need to be of split construction.

1. A pipe joint comprising external collars on adjoining pipe ends, projecting spigots on the collars, the spigots forming the pipe ends proper, a resilient sealing ring disposed between the collars and about the spigots, a split clamp ring disposed about the collars and the sealing ring and having

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in pipe joints The present invention relates to pipe joints in which adjoining pipe ends are coupled together by a clamp ring. in a known joint of this kind, the pipe ends are provided with external collars whose tapered rear faces are engaged by tapered internal walls of a split clamp ring. The wedging action of these tapered surfaces as the clamp ring is tightened about the collars causes a resilient sealing ring disposed between the collars to be axially compressed to ensure a fluid-tight seal at the joint. The sealing ring is seated about spigots projecting axially from the collars and forming the pipe ends proper. Normally these spigots remain slightly spaced apart when the clamp ring is fully tightened. It has been found that occasionally the spigots come into metai-to-metal contact before the clamp ring is fully tightened and the usual effect of this is that the clamp ring breaks or the joint leaks. A pipe joint according to the invention comprises external collars on the adjoining pipe ends, projecting spigots on the collars, the spigots forming the pipe ends proper, a resilient sealing ring disposed between the collars and about the spigots, a split clamp ring disposed about the collars and the sealing ring and having opposed internal annular tapered faces and resilient means disposed between each annular tapered face and the confronting rear face of the respective collar, such that, on tightening the clamp ring, the spigots come into direct axial abutment with one another before the clamp is fully tightened, and the resilient means yields upon completion of the clamp ring tightening. Each resilient means can comprise or consist of a resilient ring. If it consists of a resilient ring, it is directly engaged by the internal tapered face of the clamp ring. Alternatively, a loose back-up ring can be disposed between the tapered face and the resilient ring. The invention is further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a fragmentary sectional view of a known pipe joint, Fig. 2 is a similar view of a first embodiment of pipe joint according to the invention, and Fig. 3 is a similar view of a second embodiment of the invention. Fig. 1 shows a known pipe coupling in which two pipes 10, 1 1 are joined together by means including a clamp ring 12. The pipe ends have external collars 13, 14 whose annular rear faces 15, 16 are conically tapered. The clamp ring 12 is of somewhat channel-like cross section and its internal annular faces 17, 18 are complementarily conically tapered and engage the tapered faces 1 5, 1 6 of the collars. A resilient sealing ring 19 is disposed between the collars 13, 14 and is received on spigots 20, 21, which project axially towards one another from the collars 13, 14 and which form the pipe ends proper. The clamp ring 12 is a split ring so that it can be placed around the collars 13, 14 as shown and then tightened. The wedging action at the tapered faces 15,17 and 16,18 urges the collars 13,14 axially towards one another to compress the sealing ring 19. The spigots 20, 21 remain slightly spaced apart, as shown and the sealing ring 19 effects the fluid-tight seal. An internal rib 22 in the clamp ring 12 engages the sealing ring 19 to prevent the latter from bulging outwardly under the pressure to be sealed. Due to manufacturing inaccuracies, it may happen that the spigots 20, 21 will come into metal-to-metal contact before the clamp ring is fully tightened. If this should happen, the clamp ring may fracture, and even if it does not break, the seal may leak. In Figs. 2 and 3, parts like those of Fig. 1 have the same reference numerals. In the embodiment of the invention shown in Fig. 2, resilient rings 23, 24 are disposed between the internal tapered faces 17, 18 on the clamp ring 12 and the confronting annular rear faces 25, 26 on the collars 13, 14. The spigots 20, 21 are brought into axial abutment as shown before the clamp ring 12 is fully tightened. Upon continued tightening of the clamp ring, the resilient rings 23, 24 yield, thereby avoiding fracture of the clamp ring. The resilient rings 23, 24 also act as back-up sealing rings to help maintain the fluid seal. In the embodiment of Fig. 3, the resilient rings 33, 34 are relatively flat and wedge-section backup rings 31,32 are disposed between the internal tapered surfaces 1 7, 1 8 on the clamp ring 12 and the collars 13,14. The clamp ring 12 will usually be in two halves suitably bolted together. It may be cast from a metal, such as aluminium, but it is conceivable to mould them from a plastics material, such as nylon. The spigots 20, 21 are preferably formed integrally with the collars 1 3, 14 and welded to the ends of the pipes 10, 11. When the pipes are made of stainless steel, the collars are likewise of stainless steel. In an alternative method of manufacture, the collars are slipped onto the pipe ends and are welded in place, the spigots then being formed by the pipe ends themselves. The sealing ring 19 and the resilient rings 23, 24, 33, 34 are preferably of rubber. The resilient rings can be stretched over the collars to get them in place but the back-up rings 31, 32 of the Fig. 3 embodiment are preferably slipped onto the pipes before the collars are welded in place.Otherwise the back-up rings would need to be of split construction. CLAIMS

1. A pipe joint comprising external collars on adjoining pipe ends, projecting spigots on the collars, the spigots forming the pipe ends proper, a resilient sealing ring disposed between the collars and about the spigots, a split clamp ring disposed about the collars and the sealing ring and having opposed internal annular tapered faces, and resilient means disposed between each annular tapered face and the confronting rear face of the respective collar, such that, on tightening the clamp ring, the spigots come into direct axial abutment with one another before the clamp is fully tightened, and the resilient means yields upon completion of the clamp ring tightening.

2. A pipe joint as claimed in claim 1, in which each resilient means comprises or consists of a resilient ring.

3. A pipe joint as claimed in claim 1, in which each resilient means consists of a resilient ring which is directly engaged by the internal tapered face of the clamp ring.

4. A pipe joint as claimed in claim 1, in which each resilient means comprises a resilient ring and a loose back-up ring disposed between the rapered face and the resilient ring.

5. A pipe joint as claimed in any of claims 1 to 4, in which the collars and the spigots are integrally formed and are welded to the pipe ends

6. A pipe joint as claimed in any of claims 1 to 4, in which the collars are slipped over the pipe ends and are welded thereto so that the spigots are formed by the pipe ends themselves.

7. A pipe joint as claimed in any preceding claim, in which the clamp ring has an internal rib which engages the sealing ring.

8. A pipe joint constructed substantially as herein described with reference to and as illustrated in the drawings.