GB2211265A

GB2211265A - Pipe stopper

Info

Publication number: GB2211265A
Application number: GB8724366A
Authority: GB
Inventors: Kenneth Samuel Hemingway
Original assignee: International Pipeline Products Ltd
Current assignee: International Pipeline Products Ltd
Priority date: 1987-10-17
Filing date: 1987-10-17
Publication date: 1989-06-28
Anticipated expiration: 2007-10-17
Also published as: GB8724366D0; GB2211265B

Abstract

There is disclosed a pipe stopper 10 which is adapted for use in sealing a pipe section 11 so that maintenance or hydrostatic testing repair operations can be carried out. The pipe stopper may include an annular sealing device in the form of an inflatable polyurethane tyre 12 which can be inflated so as to move into sealing contact with an interior annular surface 13 of the pipe section 11, and a gripping device in the form of a pair of annular friction bands 14 which are movable under the action of the inflation of the tyre 12 so as to make gripping contact with the pipe section at a position near or adjacent to the annular surface 13 engaged by the tyre 12. The tyre may engage the outer surface of a pipe section (Fig. 2 not shown) or may engage both inner and outer surfaces of a pipe section (Fig. 3, not shown). <IMAGE>

Description

PIPE STOPPER This invention relates to a pipe stopper for use in sealing a pipe section while maintenance, or hydrostatic testing repair operations are carried out.

In this specification, the reference to a "pipe section" is intended to include any length of pipe, a pipe joint or a pipe coupling.

The invention has been developed primarily, though not exclusively, in connection with a pipe stopper for sealing a pipe section against liquid pressure action, and particularly so as to withstand substantial differential pressure action across opposed faces of the pipe stopper.

In connection with the pressure sealing of liquids, it is most important that a pipe stopper should be able to carry out a dual function, namely first of all to carry out a proper sealing function to prevent liquid ingress or egress with respect to a pipe section, and secondly so as to resist any tendency for the pipe stopper to be axially displaced as a result of any differential pressure action across the stopper.

There is a particular demand for high integrity pipe stoppers to be available for use in the North Sea oil industry, when maintenance and repair operations are required to be carried out in situ on a pipe section.

To date, attempts to maintain pipe stoppers against axial displacement in a pipe section have been relatively crude, involving direct frictional contact with the inner wall of the pipe section by a threaded fastener.

This provides very high localised pressure contact with the inner wall, with almost inevitable degradation of the surface, and the possibility of "out of round" deformation of the pipe section, which may cause of loss of sealing capability of the pipe section.

The present invention therefore seeks to provide a pipe stopper which gives a reliable sealing action, but which also has improved means of retention of the pipe stopper against axial displacement under differential pressure action.

According to the invention there is provided a pipe stopper for use in sealing a pipe section and including an annular sealing device which is inflatable so as to move into sealing contact with an annular surface of the pipe section, and a gripping device arranged to be moveable under the action of the inflation of the sealing device so as to make a gripping contact with the pipe section at a position near or adjacent to said annular surface engageable by the sealing device.

The gripping device is therefore arranged in the pipe stopper in any suitable way so as to be moveable under the action of the inflation of the sealing device.

Conveniently, the annular sealing device and the gripping device are held captive axially within a housing formed by a pair of axially spaced annular end plates, and the gripping device may engage directly with a moving surface of the annular sealing device. In one preferred arrangement, the gripping device is directly bonded to the annular sealing device, and may take the form of a circular friction band, or a pair of axially spaced bands.

The friction band may have a gritted or otherwise roughened surface to engage the surface of the pipe section. This therefore provides a multiplicity of contact points, with resulting lowering of localised contact pressure and reduced risk of undue penetration of the wall surface of the pipe section in order to provide sufficient axial restraint to the pipe stopper.

In a further preferred arrangement, the gripping device takes the form of radially moveable serrated ring segments.

To improve the sealing action of the sealing device, it may be provided with a so-called waffle pattern which comprises a mesh pattern of recesses and separating webs, the webs being deformable so as to engage with the surface of the pipe section and thereby compensate for any surface irregularity.

In a particularly suitable arrangement, the sealing device takes the form of an inflatable polyurethane tyre.

A pipe stopper according to the invention may be applied internally of a pipe section, in which case the sealing device and the gripping device are engageable with the inner wall surface of the pipe section by radially outward movement. In an alternative arrangement, a pipe stopper according to the invention may be applied externally of a pipe section, in which case the sealing device and the gripper device move radially inwardly to engage the outer wall surface of the pipe section.

According to a further modification, the pipe stopper may be engageable, upon inflation of the sealing device with both the internal and external surfaces of the pipe section.

Embodiments of pipe stopper according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a sectional illustration of a first embodiment of pipe stopper according to the invention, for use within a pipe section in order to seal and to engage the internal wall surface of the pipe section; Figure 2 is a sectional illustration of a second embodiment of pipe stopper according to the invention, adapted for application to the external surface of a pipe section; and Figure 3 is a sectional view of a third embodiment of pipe stopper according to the invention, which is capable of applying sealing action to the internal and external surface of a pipe section.

Referring first to Figure 1 of the drawings, the first embodiment of pipe stopper is designated generally by reference 10 which is intended for use within a pipe section 11 in order to seal the internal wall surface thereof while maintenance, or hydrostatic testing repair operations are carried out. As will be described in more detail below, the pipe stopper 10 is also capable of engaging the inner wall surface of the pipe section 11 in such a way as to be axially retained against movement in either direction along the axis of the pipe section.

The pipe stopper 10 includes an annular sealing device in the form of an inflatable polyurethane tyre 12 which can be inflated so as to move radially outwardly into sealing contact with an inner annular surface 13 of the pipe section 11.

The pipe stopper 10 also includes a gripping device which is arranged to be moveable under the action of the inflation of the tyre 12 so as to make a gripping contact with the pipe section 11 at a position near or adjacent to the annular surface 13 which is engaged by the tyre 12. In the illustrated embodiment, the gripping device takes the form of a pair of annular friction bands 14 which are directly bonded to the outer surface of the tyre 12 and arranged one on either side of the outer surface 15 of the tyre 12 which engages the internal wall surface 13 of the pipe section 11. The friction bands 14 may take the form of bands having bonded grit or other suitable surface roughening to engage the internal surface of the pipe section. This provides a multiplicity of contact points, with resulting lowering of localised contact pressure and reduced risk of undue penetration, while still providing sufficient axial restraint to the pipe stopper against movement in either axial direction.

In an alternative arrangement, the gripping device may take the form of a pair of radially expandable serrated ring segments, also arranged to move radially outwardly upon inflation of the tyre 12. The radially moveable ring segments are shown in the lower half of Figure 1, and are designated by reference 16. There can also be seen, in the lower part of Figure 1, a so-called "waffle" pattern 17 which comprises a mesh pattern of recesses and separating webs, the webs being deformable so as to engage with the surface of the pipe section and thereby compensate for any surface irregularity.

The sealing device (12) and the gripping device (14, 16) are held captive axially within a housing which is formed by a pair of axially spaced annular end plates 18, an internal sleeve 19 welded at each end to the end plates 18, and a hollow axial stub 20 which serves to convey liquid into or out of the pipe section 11. A valved inlet pipe 21 also extends axially through one of the end plates 18 and within the annular space defined between the stub 20 and sleeve 19, to connect with the interior of the tyre 12 for inflation and deflation purposes.

The embodiment shown in Figure 1 is intended for sealing engagement internally of a pipe section, while retaining itself against axial displacement in either direction. An alternative embodiment is shown in Figure 2 in which a pipe stopper 110 seals a pipe section 111 by sealing engagement with an outer wall surface 113 of the pipe section. Parts corresponding with those of Figure 1 are designated by the same reference numerals, but with the addition of 100. The tyre 112, the friction bands 114, or serrated vice ring segments 116, move radially inwardly to seal the outer wall surface 113, and to retain the pipe stopper 110 against axial movement.

In the embodiment 110, the pipe stopper engages over an axially outer end 122 of the pipe section 111, and has a generally channel-shaped housing 123 which contains the sealing device (112) and the gripping device (114 or 116), and which also embraces the end portion of the pipe section. The housing 123 comprises an annular portion 124, a closure plate 125 which closes-off the end 122 of the pipe section, and an annular portion 126 which surrounds the outer surface of the pipe section 111, and also retains the sealing device and the gripping device within the pipe stopper.

Finally, referring to Figure 3 of the drawings, there is shown a third embodiment which is designated generally by reference 210, and which is capable, upon inflation of the sealing device, of engaging with both the internal and external surface of pipe section 211. Parts corresponding with those already described with reference to Figure 1 are designated by the same reference numerals, but with the addition of 200. The tyre 212, and the gripping device (214 or 216) or held captive within a housing which is formed by a large end plate 222, an internal sleeve portion 223, an external sleeve portion 224, and an annular end plate 225.

Upon inflation of tyre 212, it can make sealing contact with the internal surface of the pipe section 211, and thereby also exert radially inward force to friction band 214, or serrated ring segments 216 so as to engage with the outer surface of the pipe section 211. In the illustrated embodiment, the tyre 212 does not make sealing contact with the outer surface of the pipe section, though evidently this could be arranged by suitable reduction in size of the friction band 214 or the ring segments 216, to provide a combined sealing and axial gripping action, as shown for the internal pipe stopper 10.

Claims

1. A pipe stopper for use in sealing a pipe section and including an annular sealing device which is inflatable so as to move into sealing contact with an annular surface of the pipe section, and a gripping device arranged to be movable under the action of the inflation of the sealing device so as to make a gripping contact with the pipe section at a position near or adjacent to said annular surface engageable by the sealing device.

2. A pipr stopper according to Claim 1, in which the annular sealing device and the gripping device are held captive axially within a housing formed by a pair of axially spaced annular end plates.

3. A pipe stopper according to Claim 1 or Claim 2, in which the gripping device is engageable directly with a movable surface of the annular sealing device.

4. A pipe stopper according to any one of the preceding Claims, in which the gripping device is directly bonded to the annular sealing device.

5. A pipe stopper according to Claim 4, in which the gripping device takes the form of a circular friction band, or a pair of axially spaced friction bands.

6. A pipe stopper according to Claim 5, in which the friction band(s) has a gritted or otherwise roughened surface to engage the surface of the pipe section.

7. A pipe stopper according to any one of the preceding Claims, in which the gripping device takes the form of radially movable serrated ring segments.

8. A pipe stopper according to any one of the preceding Claims, in which the sealing device is provided with a waffle pattern which comprises a mesh pattern of recesses and separating webs, the webs being deformable so as to engage with the surface of the pipe section and thereby compensate for any surface irregularity.

9. A pipe stopper according to Claim 8, in which the sealing device takes the form of an inflatable polyurethane tyre.

10. A pipe stopper according to any one of the preceding Claims and adapted for application internally of a pipe section, in which the sealing device and the gripping device are engageable with the inner wall surface of the pipe section by radially outward movement.

11. A pipe stopper according to any one of Claims 1 to 9 and adapted for application externally of a pipe section, in which the sealing device and the gripper device are movable radially inwardly to engage the outer wall surface of the pipe section.

12. A pipe stopper according to any one of Claims 1 to 9 and adapted, upon inflation of the sealing device, to engage with both the internal and external surfaces of the pipe section with which it is to be used.

13. A pipe stopper according to Claim 1 and substantially as hereinbefore described with reference to, and as shown in any of the embodiments illustrated in the accompanying drawings.