GB2143605A - Swivel joint - Google Patents

Abstract

A swivel joint (1) for coupling pipes, comprises an inner hollow part (2) arranged coaxially within an outer hollow part (4), a ball bearing (10) and a needle bearing (12) disposed between the two parts (2,4) so as to facilitate relative rotary movement therebetween, and a resilient ring seal (8) positioned between the two parts (2,4) so as to prevent flow of fluid from within the parts (2,4) to the bearings (10,12), the ends of the two parts (2,4) remote from the bearings (10,12) being adapted to receive the pipes to be coupled. The needle bearing may be a roller bearing. <IMAGE>

Description

SPECIFICATION Swivel joint This invention relates to swivel joints and more especially it relates to swivel joints for pipes.

In orderto provide for coupling and relative movement between two pipes carrying gas or liquid, it is known to use a swivel joint between the two pipes. In use, such swivel joints should be capable of withstanding rough treatment without leaking whilst carrying fluid under pressure.

It is an aim of the present invention to provide a swivel joint having the characteristics just before mentioned, and which swivel joint is simple to manufacture and simple to assemble.

Accordingly, this invention provides a swivel joint for coupling pipes, which swivel joint comprises an inner hollow part arranged coaxially within an outer hollow part, a ball bearing and a needle bearing disposed between the two parts so as to facilitate relative rotary movement therebetween, and a resilient ring seal positioned between the two parts so as to prevent flow of fluid from within the parts to the bearings, the ends of the two parts remote from the bearings being adapted to receive the pipes to be coupled.

The swivel joint is basically of a simple two part construction of the inner hollow part and the outer hollow part. There is no need for intermediate gaskets which could leak and the resilient ring seal can be arranged to extend axially over a relatively long distance to provide a long leak-prevention path.

The needle rollers are effective to provide a load bearing surface which thus advantageously spreads the load on the swivel joint. The swivel joint is thus able to resist cantilever loads and to seal whilst conveying fluid under pressure.

The ball bearing and the needle bearing may be made in a wide variety of sizes. As needle bearings increase in size, they are sometimes called roller bearings. It is to be understood that the term "needle bearings" used herein also includes roller bearings, the term "roller bearings" merely being a term that is sometimes used for large needle bearings.

The outer part may include an internal circumferential groove in which the sealing ring is received.

The inner part may include an end portion which is of reduced diameter and which fits within a complementary step portion within the outer part and in which complementary step portion the groove for the ring seal is provided.

The end portion of the inner part may have its outer circumferential surface covered with a friction reducing material such for example as polytetrafluoroethylene.

The ball bearing may be positioned coaxially of the two parts between the needle bearing and the ring seal. If desired, howeverthe needle bearing may be positioned coaxially of the two parts between the ball bearing and the ring seal.

In order to prevent the ingress of dust between the inner part and the outer part, a dust sealing collar may be provided which tightly embraces the inner part and which fits contiguously against the outer part.

The outer part may include a lubrication nipple via which lubricant may be injected to the bearings.

The ends of the two parts remote from the bearings may be screw threaded in order to receive the pipes to be coupled.

Alternatively, the ends of the two parts remote from the bearings may be provided with flanges.

The two parts may be made of steel such for example as mild steel or stainless steel. Alternatively, the two parts may be made of cast iron, aluminium or bronze.

The sealing ring may comprise an elastomer, for example, a nitrile rubber.

The ring seal may be of a two part construction comprising a sealing ring and a wear ring. The wear ring may fit in an axially extending recessed portion of the sealing ring.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 is a somewhat schematic sectional side view of a first swivel joint; Figure 2 is a section through the top part of the swivel joints shown in Figure 1 and illustrates how the ball bearings are loaded and retained; and Figure 3 is a partially cut-away view showing a second swivel joint.

Referring now to Figures 1 and 2, a swivel joint 1 for coupling pipes comprises an inner generally cylindrical hollow part 2 which is fitted coaxially within an outer generally cylindrical hollow part 4.

The outer part 4 includes an internally formed circumferential groove 6 within which a resilient ring seal 8 is fitted. The ring seal 8 is of a two part construction comprising a sealing ring 9 and a wear ring 11. The sealing ring 9 is made from an elastomer in the form of a nitrile rubber. The sealing ring 9 has a relatively large cross sectional area as will be seen and it is adapted to afford a long life and a good resistance to high pressure in service. The wear ring is made from polytetrafluoroethylene which is a friction reducing material.

In order to facilitate relative rotary movement between the inner part 2 and the outer part 4, a concentrically arranged ball bearing 10 and a concentrically disposed needle bearing 12 are provided, these being of standard construction.

In order to prevent the ingress of dust or other foreign matter between the inner part 2 and the outer part 4, a dust sealing collar 14 is provided whih fits tightly over the inner part 2 and which contiguously abuts the outer part 4.

The sealing ring 9 rubs against a reduced diameter end portion 16 of the inner part 2. The inside of the outer part 4 in which the groove 6 is formed is provided with a complementary step 7. The wear ring 11 minimises friction between the sealing ring 9 and the end portion 16 of the inner part 2.

To facilitate lubrication of the ball bearing 10 and the needle bearing 12, a grease nipple 20 is provided via which grease or other lubricant may be introduced to the ball bearing 10 and the needle bearing 12. It will be appreciated that the construction of the dust seal 14 enables excess lubricant under pressure to be expelled between the dust seal 14 and the outer part 4.

Ends parts 24 and 26 of the inner part 2 and the outer part 4 respectively may be screw threaded to receive complementary screw threads on pipes to be coupled, or they may be adapted for welding to pipes to be coupled. The ends parts 24 and 26 may alternatively be flanged (not shown) and arranged to afford a straight through connection as shown in Figure 1. Alternatively however, a bent or cranked coupling may be provided affording a 90" bend and it is contemplated that in one embodiment a double 90" outlet pipe may be provided for. Furthermore, fabricated assemblies are envisaged using weld, threading or vacuum brazing techniques.

By providing a needle bearing in addition to a ball bearing, high load carrying capacity is afforded and rough usage is more easily withstood. The ball bearing assembly is effected via a threaded hole 28 (see Figure 2) in the outer part 4. The hole 28 is plugged with a screwed nylon plug 30. The plug 30 is in turn covered over with a name plate 32 which is riveted in position by rivets 34 to retain the plug 30 in position. Preferably, the name plate 32 is made from aluminium.

The swivel joint just before described has the special advantage that a retaining arrangement is not required for the ring seal 8 to hold it in place.

Referring now to Figure 3, similar parts as in Figures 1 and 2 have been given the same reference numerals and their precise construction and operation will not again be given. In Figure 3, the name plate 32 is omitted and the ring seal 8 is a one part block ring and the wear ring 18 has been omitted.

Figure 3 serves to illustrate how the balls of the ball bearing 10 serve to hold the parts 2,4 of the swivel joint together and to take axial loads, whilst the closely packed needle rollers of the needle bearing 12 take high radial loads. The ring seal 8, positioned inboard ofthetwo bearings 10,12, allows for movement with low torque. The ring seal 8 is of course manufactured from materials which are compatible with the operating conditions and the particular fluid passing through the swivel joint 1.

It is contemplated that swivel joints as herein before described with reference to the drawings may be provided to fit pipe sizes from 1 to 6 inches (2.5 to 15,5 cm) internal diameter. If desired, the swivel joint may be produced to fit pipes up to 36 inches (92 cm) in internal diameter. It will normally be arranged that the internal diameter of the joint is at least as large as the internal diameter of the pipes to be coupled, whereby no flow restriction is introduced by the joint. The swivel joints may provide 360" movement in one or more planes dependent on style. The swivel joints may work at pressures up to 1000 p.s.i.

for example and at swivel speeds of up to 60 revolutions per minute. The swivel joints may be used for many process plant applications, wash system designs, slowly rotating drums, and similar situations where offset loads are a problem.

Various modifications may be made to the swivel joints herein before described with reference to the drawings without departing from the scope of the invention. For example, it will be appreciated that the material from which the various parts of the joints are manufactured will be chosen in accordance with the application in view and thus different materials such as plastics materials may be chosen where the joint is used in connection with foodstuffs, steam or oil products for example. Furthermore, the needle bearing 12 may advantageously be recessed into the inner part 2 (as shown in dotted lines 36 in Figure 1) instead of being recessed into the outer part 4 as shown in Figure 1. Generally, it is easierto machine the inner part 2 to receive the needle bearing 12 than to machine the outer part 4.

Furthermore, the relative positions of the ball bearing 10 and the needle bearing 12 may be reversed if desired. Also, the balls 40 of the ball bearing 10 could run in a helical groove instead of the single straight groove 42 shown in Figure 3, the helical groove allowing axial relative movement of the parts 2,4 and the needle bearing 12 and the ring seal 8 being able to accommodate any such axial movement.

Claims (11)

1. A swivel joint for coupling pipes, which swivel joint comprises an inner hollow part arranged coaxially within an outer hollow part, a ball bearing and a needle bearing disposed between the two parts so as to facilitate relative rotary movement therebetween, and a resilient ring seal positioned between the two parts so as to prevent flow of fluid from within the parts to the bearings, the ends of the two parts remote from the bearings being adapted to receive the pipes to be coupled.

2. A swivel joint according to Claim 1 in which the outer part includes an internal circumferential groove in which the ring seal is received.

3. A swivel joint according to Claim 2 in which the inner part includes an end portion which is of reduced diameter and which fits within a complementary step portion within the outer part and in which complementary step portion the groove for the ring seal is provided.

4. A swivel joint according to Claim 3 in which the end portion of the inner part has its outer circumferential surface covered with a friction reducing material.

5. A swivel joint according to any one of the preceeding claims in which the ball bearing is positioned coaxially of the two parts between the needle bearing and the ring seal.

6. A swivel joint according to any one of the preceeding claims and including a dust sealing collar which tightly embraces the inner part and which fits continuously against the outer part.

7. A swivel joint according to any one of the preceeding claims in which the outer part includes a lubrication nipple via which lubricant may be injected to the bearings.

8. A swivel joint according to any one of the preceeding claims in which the two parts remote from the bearings are screw threaded or provided with flanges.

9. A swivel joint according to any one of the preceeding claims in which the ring seal is made from an elastomer.

10. A swivel joint according to any one of the preceeding claims in which the ring seal is of a two part construction comprising a sealing ring and a wear ring.

11. A swivel joint for coupling pipes, substantially as herein described with reference to the accompanying drawings.