GB2032562A - Improvements in or relating to pipe joints - Google Patents

Abstract

A pipe joint comprises two mating annular flanges 12, 13 on the ends of the pipes 10, 11 to be joined, the flanges being so shaped that when mated together an annular enclosed chamber 14 is defined between them. The junction between the flanges both radially inwardly and radially outwardly of the chamber 14 incorporates air-tight seals, and at least one of the flanges includes a closable outlet 15 through which air may be evacuated from the chamber so that the two flanges 12, 13 are then held together by external atmospheric pressure. <IMAGE>

Description

SPECIFICATION Improvements in or relating to pipe joints The invention relates to pipe joints and sets out to provide a leakproof joint which is easy to assemble and which, though extremely strong, may be easily and rapidly taken apart.

A common joint for pipes, particularly large diameter metal pipes, comprises two mating radial flanges on the ends of the pipes to be joined, the two flanges having registering holes through which bolts are passed to bolt the flanges together. Assembling such a joint is laborious due to the necessity of aligning the holes in the two flanges and maintaining them in alignment while the bolts are fitted. Also access to some of the bolts may be difficult if the joint is to be located in a confined space. Furthermore, since the bolts are spaced apart around the circumference of the flanges, the clamping pressure on the flanges is not evenly distributed but is highest at the location of the bolts and lower between the bolts. This can lead to distortion of the flanges and leakage. It is an object of the invention to provide a pipe joint which overcomes these disadvantages.

The invention may also provide a joint suitable for pipes of a material which does not permit the pipes being bolted together as described above, and a joint where failure of the joint may be readily detected.

According to the invention there is provided a pipe joint comprising two mating annular flange structures for mounting on the ends of the pipes to be joined, or integral with said ends, the flange structures being so shaped that when mated together an annular enclosed chamber is defined between them, the junction between the flanges both radially inwardly and radially outwardly of the chamber incorporating air-tight sealing means, and at least one of the flange structures including a closable outlet through which air may be evacuated from the chamber so that the two flange structures are then held together by external atmospheric pressure.

A pipe joint in accordance with the invention is simple to assemble since there are no bolt holes to be aligned.

The air-tight sealing means may comprise resilient gaskets, for example each resilient gasket comprising an O-ring portion received in mating annular recesses in the flange structures, and a flat portion integral with the O-ring portion and disposed between the opposing surfaces of the flange structures adjacent said recesses.

To facilitate correct mating engagement between the flange structures, one of the flange structures may be formed with an axially projecting peripheral lip within which the other flange structure is located when the two flange structures are in the correct mating position.

Preferably there are provided retaining means engageable with said flange structures in a manner to retain the flange structures in mating engagement with one another when they are no longer held together by external atmospherical pressure. For example, the retaining means may comprise one or more part-annular detachable collar elements partly surrounding and embracing the mating flange structures and having releasable means clamping the collar elements to the flange structures.

In order to detect leakage of the joint there may be provided pressure sensitive means responsive to the pressure within the annular closed chamber between the mating flange structures, and arranged to provide a signal upon said pressure exceeding a predetermined value. The signal may then be arranged to activate visual and/or audible indicating means, which may be remote from the pipe joint.

The following is a more detailed description of various embodiments of the invention, reference being made to the accompanying drawing which is a diagrammatic view, partly in side elevation and partly in longitudinal section, of a pipe joint in accordance with the invention.

The two pipes 10 and 1 1 to be joined are circular in cross-section, and are integrally formed at their adjacent ends with abutting, radialy extending flanges 12 and 13 respectively.

The flange 12 is provided around its periphery with an axially projecting lip 1 2a within which the flange 13 is received. This facilitates assembly of the flanges together in the correct mating position.

Instead of the mating flanges of the pipe joint being integrally formed with the pipe as shown, they may be separately formed and secured to the ends of the pipes, for example by welding.

In the case of metal pipes, the mating radial faces of the flanges may be machined flat after casting. The faces are formed with annular recesses which cooperate when the flanges are in mating engagement, as shown, to define an annular vacuum chamber 14. An outlet 1 5 leads through the flange 12 from the chamber 14 and is controlled by an outlet valve 16.

The mating surfaces of the flanges are also formed with registering annular semi-circular section grooves radially inwards and outwards of the annular chamber 14, which grooves receive 0rings to provide an air-tight seal. Each O-ring may have integrally formed therewith flat sealing portions disposed between the opposing surfaces of the flanges on either side of the O-ring, so as to form an annular gasket 17.

The outer edge of the radially outer gasket may also project between the axial lip 1 2a and the outer peripheral surface of the flange 1 3.

Two or more part-annular collar elements 18, each of channel section, partly surround and embrace the mating flanges 12 and 13 so as to retain the flanges in engagement with one another when they are no longer held together by external atmospheric pressure, in a manner to be described. The collar elements, two of which are employed in the illustrated pipe joint, are spaced apart around the flanges. The elements are so dimensioned in cross-section as to be an interference fit with the flanges. The collar elements 18 are located on the flanges by means of Allen screws 1 9 which are threaded through the side walls of the collar elements 18 and engage a suitably located annular groove 20 in the surface of the flange 13.

To assemble the joint, the gaskets 17 are first fitted into the machined grooves in the flange 12 and the flanges 12 and 13 are then brought into mating engagement as shown. The flanges are then clamped together. This may either be done by means of the collar elements 18, which may be subsequently left in place, or by means of separate temporary clamps. A vacuum pump is then connected to the valve 16 and air is withdrawn from the chamber 14 until the required vacuum is reached. The valve 16 is closed and the pump disconnected, and the flanges will then be held together by the external atmospheric pressure. If temporary clamps have been used to hold the flanges in place these are then removed and the collar elements 18 fitted if required.Alternatively if the collar elements 1 8 themselves have been used to hold the flanges while the chamber 14 is evacuated, these collar elements may be left in place.

The collar elements 18 are not essential to the strength of the joint when it is under atmospheric pressure but serve merely to maintain the flanges in alignment should there be a failure of the atmospheric joint. They may not be required if the pipes are otherwise supported in position.

There may be mounted in or on one of the flanges a pressure sensitive device 21 communicating with the chamber 14 and of a kind arranged to provide signal should there be a rise in pressure in the chamber 14 above a predetermined value, indicating failure, or imminent failure of the joint. The signal, which may be an electrical signal, is transmitted along a line 22 to a junction box 23 and thence to a central control area remote from the joint.

The central control area may be arranged to monitor signals from all the joints in a pipeline or installation so as to detect failure or imminent failure of any joint. There may be provided in the control area an audible alarm which is activated upon receipt of a signal from a pipe joint, and/or other information processing equipment such as a visual display identifying the state of the joints in the pipeline and a print-out assembly which provides written notification of the location of any joint requiring servicing.

The pressure sensitive devices associated with the respective pipe joints may comprise electronic sensors, the sensors of the various pipe joints emitting signals having different characteristics so that the pipe joint from which the signal is emitted can be identified by the nature of the signal.

Since the pipe joint according to the invention must be air-tight in order to maintain the vacuum between the flanges, it follows that it will also be completely fluid-tight to that there is no danger of gradual leakage of the fluid flowing through the pipes while the joint is operational.

Leakage will only occur upon loss of vacuum, and this can be detected, as described.

When it is required to separate the joint the closable outlet is simply opened to admit atmospheric air into the annular chamber whereupon the two parts of the joint should easily separate. If the two parts are difficult to separate, for example due to corrosion, air under pressure can be introduced into the chamber to force the flange structures apart.

The invention is particularly suitable for joining pipes formed from materials which give rise to problems in forming a joint by permanently clamping the ends of the pipes together by mechanical means. For example such problems may arise with materials such as glass, lightweight metals and fibreglass.

Claims (11)

1. A pipe joint comprising two mating annular flange structures for mounting on the ends of the pipes to be joined, or integral with said ends, the flange structures being so shaped that when mated together an annular enclosed chamber is defined between them, the junction between the flanges both radially inwardly and radially outwardly of the chamber incorporating air-tight sealing means, and at least one of the flange structures including a closable outlet through which air may be evacuated from the chamber so that the two flange structures are then held together by external atmospheric pressure.

2. A pipe joint according to claim 1, wherein the air-tight sealing means comprise resilient gaskets.

3. A pipe joint according to claim 2, wherein each resilient gasket comprises an O-ring portion received in mating annular recesses in the flange structures, and a flat portion integral with the 0ring portion and disposed between the opposing surfaces of the flange structures adjacent said recesses.

4. A pipe joint according to claim 3 or claim 4, wherein one of the flange structures is formed with an axially projecting peripheral lip within which the other flange structure is located when the two flange structures are in the correct mating position.

5. A pipe joint according to any of claims 1 to 4, comprising retaining means engageable with said flange structures in a manner to retain the flange structures in mating engagement with one another when they are no longer held together by external atmospheric pressure.

6. A pipe joint according to claim 5, wherein said retaining means comprise one or more partannular detachable collar elements partly surrounding and embracing the mating flange structures and having releasable means clamping the collar elements to the flange structures.

7. A pipe joint according to claim 6, wherein said releasable clamping means comprise a clamping screw threadedly engaging the or each collar element and engageable with a recess in one of the flange structures.

8. A pipe joint according to any of claims 1 to 7, including pressure sensitive means responsive to the pressure within the annular closed chamber between the mating flange structures, and arranged to provide a signal upon said pressure exceeding a predetermined value.

9. A pipe joint according to claim 8, including visual and/or audible indicating means arranged to be activated by said signal.

10. A pipe joint according to claim 9, wherein said indicating means are located remotely from the pipe joint.

11. A pipe joint substantially as hereinbefore described with reference to the accompanyig drawings.