GB2150246A

GB2150246A - Pipe joint seal

Info

Publication number: GB2150246A
Application number: GB08429555A
Authority: GB
Inventors: John Alexander Inshaw; Robinson Brown; William Alexander Dodd
Original assignee: RUSSELL FOSTER HOLDINGS Ltd
Current assignee: RUSSELL FOSTER HOLDINGS Ltd
Priority date: 1983-11-23
Filing date: 1984-11-22
Publication date: 1985-06-26
Also published as: GB8429555D0; GB8331220D0; GB2150246B

Abstract

The present invention provides a pipe-joint seal 4 suitable for use in sealing a Carlton-type joint, which comprises an annular element 14 of a semi-rigid resiliently deformable elastomeric material. The seal 4 has a generally ridge-shaped cross-section with a central radially outwardly extending rib 5 at its apex 6 and on opposite sides thereof two generally part-circular flanks 7 having a radius of curvature corresponding generally to that of the bell shaped pipe ends 2 in said Carlton joint 1. In a further aspect the invention provides a Carlton-type pipe joint 1 comprising two pipes with belied ends 2, a seal 4 of the invention, and an annular clamp 9, formed and arranged for clamping said belled pipe ends 2 against said seal 4. <IMAGE>

Description

SPECIFICATION Pipe joint seal The present invention relates to a pipe joint seal and in particular to a seal suitable for use in a Carlton type joint.

Carlton joints have been used extensively for a great many years in coal mines and other underground workings in connections between adjoining sections in steel pipes used for carrying water or gas. Conventionally such joints are made with sealing members in the form of annular rings of cast-iron with radially outer surfaces comprising oppositely inclined flanks extending on either side of a central annular rib, and rubber'0'-rings mounted in circumferentially extending grooves close to the axially outer edges of the inclined flanks. Such seals tend to be rather heavy especially for larger diameter pipe sizes and thus are difficult to handle and to correctly position during installation.Moreover the 'O'-rings provide only a limited sealing area even when they are correctly positioned so that additional sealing means e.g.

bituminous paint often require to be used. In practice though sealing is often adversely affected by damage to the 'O'-rings and/or displacement thereof from their mounting grooves due inter alia to the difficulties of handling thereof.

It is an object of the present invention to avoid or minimize one or more of the above disadvantages.

The present invention provides a pipe-joint seal suitable for use in sealing a Carlton-type joint, which seal comprises an annular element of a semi-rigid resiliently deformable elastomeric material and having a generally ridge-shaped cross-sectional shape with a central radially outwardly extending rib at its apex and on opposite sides thereof two generally part-circular fianks having a radius of curvature corresponding generally to that of the bell shaped pipe ends in said Carlton joint.

In a further aspect the present invention provides a Carlton-type pipe joint comprising two pipes with belled ends, a seal of the invention, and an annular clamp, formed and arranged for clamping said belled pipe ends against said seal.

With a seal of the present invention it is possible to reliably and easily achieve a good degree of sealing, as a result of interalla the extended sealing area, the security and integrity of the sealing portions, and the general ease of handling and installation of the seal.

Further preferred and advantageous features of the present invention will appear from the following detailed description given by way of example of two preferred embodiments illustrated with reference to the accompanying drawings wherein: Fig. 1 is a radial cross-section through a Canton joint with a first seal of the present; Fig. 2 is a similar view showing a second seal of the invention; and Fig. 3 is a partly sectioned side view of the seal of Fig. 2, Fig. 1 shows a Carlton-type pipe joint 1 between two adjoining pipe section ends 2. The ends 2 are belled so as to have, in radial cross section, a generally part-circularform having a radius of curvature R generally in the region of from 2/3 to 3/4 of the outside diameter OD of the pipe 3.

An annular sealing member 4 is generally triangular in radial cross-section with a central rib 5 at the radially outward apex 6 and oppositely inclined flanks 7 generally complementary to the internal surfaces 8 of the belled pipe ends 2, on either side of said rib 5.

A ring clamp 9 has a grooved radially inner surface 10 with opposed side walls 11 generally complementary to the radially outward surfaces 12 of the respective belled pipe ends 2, and has lugs 13 supporting clamping bolt end nut means 14 for applying a radially inward clamping force through the hinged main body 15 of the clamp 9. As the ring clamp is tightened about the belled ends 2 it draws them axially towards each other against the opposed flanks 7 of the sealing member 4 to form an extended seal therewith as the sealing member 4 is resiliently deformed by said belled ends 2.

The sealing member is formed and dimensioned so that its inside diameter corresponds approximately to that of the pipe so that its interior is generally flush with that of the pipe except for a small bevelling 16 of the edges at each axial end 17.

The central rib 5 is dimensioned to have a height slightly less than that of the pipe wall thickness so that it does not interfere with the pipe clamp but is sufficient to act as a restraint for limiting relative angular displacement between adjoining pipe sections, the edges of the belled pipe ends 2 abutting the sides of the rib at the maximum angular deviation between the longitudinal axes of the pipe sections.

Figs. 2 and 3 show a further improved seal of the invention, like parts corresponding to those in Fig. 1 being identified by like reference numerals. In this case the oppositely inclined outwardly disposed flanks 7 of the sealing member 4 are provided with a plurality of outwardly projecting sealing ribs 18.

These are conveniently formed integrally with the main body of the sealing member 4 e.g. by the use of a suitable mould ab initio or by post-forming e.g.

suitable machining of the flanks. Alternatively the sealing ribs could be formed separately and then secured to the main body of the sealing member 4 by any suitable means. Conveniently, grooves 19 could be formed in a plain flank surface 7 and separately formed O-rings 20 secured in place therein with the aid of a suitable adhesive, with part 21 of the O-rings projecting above the flanks 7.

The number of sealing ribs 18 provided on each flank may be readily varied from one to several (greater numbers generally increasing security of sealing), as may also their height, width, crosssectional shape, and, where more than one rib is provided on each flank, their spacing. In general though the ribs are more or less rounded, preferably generally semi-circular and conveniently have a height of from 1/4 to 3/4 of the pipe wall thickness or from 1/2 to approximately equal to the height of the rib 5.

As may be seen from the drawing with a sealing member of the present invention pressure is applied to it over a wide area giving rise to a large sealing contact. At the same time the sealing member is easy to handle and position for reliably obtaining a good seal.

The sealing member may be made of various resiliently deformable elastomeric materials including natural or synthetic polymers such as natural or synthetic rubber. Preferably there is used a relatively hard, generally semi-rigid material such as flame resistant polychloroprene. In general the hardness of the rubber used will depend on the expected line pressure with softer rubbers e.g. those having a hardness in the range of from 50 to 70 IHRD providing better sealing at lower pressures and harder rubbers e.g. those having hardness in the range of from 70 to 90 lHRD providing better performance at higher pressures. At particularly high pressures the seal is desirably reinforced e.g.

with a metal sleeve 22 (See Fig. 2) at its radially inner wall or with other stiffening moulded integrally into the interior of the seal.

Further advantages provided by the present invention that may be mentioned include the avoidance of the relatively laborious and potentially damaging practice of excessive tightening and hammering of the parts required in a conventional type Carlton joint in order to achieve optimum seating of the parts and adequate sealing. With the seal of the present invention slight inaccuracies in sealing and deformations in the pipe ends can be readily accommodated without the need for extensive manipulation and excessive tightening.

Moreover the resiliently deformable nature of the central rib 5 permits greater angulation at pipe joints by the ability of this rib to safely yieldably deform when a pipe end is pressed against it. Also the overall weight of the sealing member is considerably less than that of the ferrule used in previously known systems thereby considerably facilitating handling.

Claims

1. A pipe joint seal suitable for use in sealing a Carlton-type joint, which seal comprises an annular element of a semi-rigid resiliently deformable elastomeric material and having a generally ridge shaped cross-sectional shape with a central radially outwardly extending rib at its apex and on opposite sides thereof two generally part-circular flanks having a radius of curvature corresponding generally to that of the bell shaped pipe ends in said Carlton joint.

2. A seal as claimed in claim 1 for use in a Carton type joint of a predetermined size with pipe walls of a predetermined thickness, wherein said central rib of said seal has a height slightly less than said predetermined pipe wall thickness.

3. A seal as claimed in claim 1 or claim 2 wherein each said flank is provided with at least one sealing rib.

4. A seal as claimed in claim 3 wherein each said flank is provided with a plurality of sealing ribs.

5. A seal as claimed in claim 3 or claim 4 wherein the sealing ribs are formed integrally with the main body of the seal.

6. A seal as claimed in any one of claims 3 to 5 wherein the sealing ribs have a generally rounded section.

7. A seal as claimed in any one of claims 1 to 6 which seal is made of natural or synthetic rubber.

8. A seal as claimed in claim 7 wherein said seal is made of flame-resistant polychloroprene.

9. A seal as claimed in any one of claims 1 to 8 wherein is provided a reinforcing means formed and arranged for stiffening the main body of the seal.

10. A seal as claimed in claim 9 wherein the reinforcing means comprises a steel plate.

11. A pipe-joint seal suitable for use in sealing a Carlton-type joint, substantially as described hereinbefore with particular reference to Fig. 1 or Figs. 2 and 3 of the accompanying drawing.

12. A Carlton-type pipe joint comprising two pipes with belled ends, a seal according to claim 1, and an annular clamp, formed and arranged for clamping said belled pipe ends against said seal.

13. A Carlton-type pipe joint comprising two pipes with belled ends, a seal, and an annular clamp, substantially as described hereinbefore with particular reference to Fig. 1 or Figs. 2 and 3 of the accompanying drawing.