GB2349673A - Inflatable seal - Google Patents

Abstract

A generally circular bladder seal comprises an inflatable bladder (1) having a concave profile which is attached at its inner wall (13) to a pipeline pig (16) and at its outer wall (14) to a hard plastic outer ring (2). A softer plastic sealing ring (3) is provided in a recess of the outer ring (2) to effect a true seal between the bladder seal and an inner wall of a pipe. The bladder (1) is inflated with a fluid by way of a male connector (5), the bladder (1) being inflated or deflated to vary the diameter of the bladder seal so that the plug (16) may be used in pipelines of varying widths.

Description

BLADDER SEAL The present invention relates to a seal for use in conjunction with pipeline plugging equipment.

Pipeline plugs are used in industry in order to provide isolation seals in pipelines so that, for example, sections of a pipeline may be tested without ingress of fluid. Plugs are now used in a wide variety of industries, but are still most commonly used in the oil, gas, and petrochemical industries. However, known plugs have seals of specific diameters, and as a result different plugs must be used in different diameters of pipeline.

It is therefore the aim of the present invention to provide an adjustable sealing element for use with pipeline plugs, so that a single plug may operate in a range of pipelines with varying diameters while still maintaining a secure seal between the plug and the internal wall of the pipeline.

According to the present invention, there is provided an annular seal for sealing between the internal wall of a tube member and a cylindrical member disposed within the tube member, said seal comprising: a resilient annular outer member provided with an annular seal at its outer circumferential surface; and an inflatable annular inner member disposed adjacent to the inner circumferential surface of said annular outer member and provided with an inflation insert adapted to permit the passage of fluid for inflating said annular inner member.

Preferably, said annular seal comprises a sealing member of material softer than the material of the annular outer member, the sealing member being disposed within a circumferential recess in the annular outer member.

Preferably, said inner member comprises a pair of opposing concave side walls, said side walls being adapted to concertina between a collapsed position when the inner member is deflated, and an expanded position when the inner member is inflated. Preferably, the inner member further comprises an inner wall and an outer wall joined by said side walls, whereby the inner and outer wall remain substantially parallel to each other when the inner member moves from the deflated state to the inflated state.

Preferably, the material of the inner member is resilient and has a lower stiffness than the material of the outer member.

Preferably, the annular seal further comprises a plurality of arcuate ring segments disposed at a first outer edge of said outer member, and a plurality of link members, each link member linking two adjacent ring segments. Preferably, each of said arcuate ring segments is provided with a plurality of detent portions on the outer circumferential surface thereof.

Preferably, said detent portions are integrally formed with said arcuate ring segments, and are disposed in a direction away from said first outer edge.

Preferably, said arcuate ring segments and said link members are provided with apertures, said outer member is provided with threaded inserts and said arcuate ring segments and said link members are secured to said threaded inserts by threaded fasteners.

Preferably, said arcuate ring segments and said link members are of a material. of greater stiffness than the material of the outer member. Preferably, said arcuate ring segments and said link members are of metal. Most preferably, said arcuate ring segments and said link members are of high-grade carbon steel and the outer member is of polyproylene.

Preferably, said arcuate ring segments extend within a recess in the outer member over at least half the radial thickness of the outer member. Preferably, the respective cross-sectional profiles of said link members and said arcuate ring segments are such so as to permit relative movement in a circumferential direction but to prevent relative movement in a radial or axial direction.

Preferred embodiments of the present invention will now be described, with reference to the accompanying drawings, in which: Figures l (a) and l (b) show a bladder as used in the bladder seal of the present invention; Figure 2 shows a detail of the bladder shown in Figure i (b) ; Figure 3 shows a sectional view of a bladder seal in accordance with the present invention for use in low pressure applications; Figure 4 shows a sectional view of a second embodiment of a bladder seal in accordance with the present invention for use in high pressure applications; Figure 5 shows a sectional view of a third embodiment of a bladder seal in accordance with the present invention; and Figure 6 shows a detail view of the anti-extrusion device of the present invention.

Referring to the drawings, Figure 1 shows an annular tubular bladder 1 manufactured from a resilient plastics material such as polyurethane which forms an integral part of the bladder seal of the present invention. Figure l (b) shows a sectional view of the bladder 1, where it can be seen that the side walls 22 of the bladder 1 have a concave profile. The bladder 1 has an inner area 10 which can be filled with a predetermined volume of fluid. The bladder 1 has a number of openings 11 located around its inner circumference, and one of these openings has an inflation insert 4 fitted to permit inflation of the bladder 1, as seen best in Figure 2. The remaining openings 11 are filled by pressure plugs (not shown).

The side walls 22 have a concave profile so that when the bladder 1 is fully deflated, the walls 13,14 of the bladder 1 lie flat on top of each other as seen in Figure 3. When the bladder 1 is deflated, the walls 13,14 concertina so that the outer wall 14 of the bladder remains substantially parallel to the inner wall 13. Were the bladder 1 a straightforward tubular shape, when it deflated the tube would fold in on itself leaving irregular folds which may be higher at one side of the bladder than the other, which could leave part of the bladder 1, or the outer ring 2 proud of the plug.

Figure 3 shows all of the components of one of the preferred embodiments of the bladder seal. The seal is intended to be located in a circumferential recess 15 provided around the exterior of a pipeline plug body 16 in order to seal the annular gap between the external wall 17 of the plug 16 and the wall of the pipeline, when the bladder 1 is inflated. The inner wall 13 of the bladder 1 is attached to the plug 16. An outer ring 2 manufactured from a hard plastics material such as hard polyurethane is attached to the outer wall 14 of the bladder 1. The outer ring 2 and the bladder 1 have a width such that they fit and can move within the recess 15. In addition, to effect a true seal between the bladder seal and the pipeline, a sealing ring 3 is provided in a recess of the outer ring 2. This sealing ring 3 is made from a softer plastics material than the outer ring 2 so that a secure seal is effected between the bladder seal and the internal wall of the pipeline.

Figure 3 also shows how the fluid used to inflate the bladder 1 is provided. A tube 6 is connected to the bladder 1 by way of a male connector 5 which is screwed into the inflation insert 4 of the bladder 1. The bladder 1 can then be inflated or deflated to vary the size of the seal, so that the plug may be used in a variety of pipelines of differing internal diameters, but will still have a secure seal.

Figure 4 shows the bladder seal with an optional antiextrusion device 12 fitted. The device 12 is fitted to the leading edge of the bladder seal in order to prevent the seal from being extruded in the gap between the pig and the pipeline wall under high pressure from direction A. The device 12 improves the rigidity of the bladder seal and consists of a high-grade carbon steel ring 8 segmented to form a plurality of arcuate ring segments linked to each other by an equal number of leading edge portions or link members 7. The steel ring 8 is segmented so as to permit the expansion of the seal when the bladder 1 is expanded. The segmented ring 8 and leading edge portions 7 are secured to the outer ring 2 of the bladder seal by bolts 9, with the leading edge portions 7 being secured in position over the gaps between the segments of the inner ring 8, as can be seen in Figure 6. The bolts 9 engage in threaded inserts 23 cast into the outer ring 2. The leading edge portions 7 are each provided with two apertures 24, and they span between two adjacent steel ring segments 8. The apertures 24 in each leading edge portion 7 have a diameter greater than the diameter of the bolt 9 so as to allow some movement or"play"in the circumferential direction, thus allowing for a certain amount of expansion between the ring segments 8 and the leading edge portions 7. As can best be seen in Figure 6, the ring segments 8 have contoured lip portions 8a, 8b that ensure that when the bolts 9 are fitted, only movement in the circumferential direction is permitted between the ring segments 8 and the leading edge portions 7, and no movement between the two respective elements is allowed in the axial or radial directions.

Another optional device for inclusion with the bladder seal is a steel gripper insert 18, as can be seen in Figure 5. The gripper 18 is manufactured from the same material as the anti-extrusion device 12 described above and can be added to the bladder seal in order to provide a low pressure isolation seal within a pipe.

As with the anti-extrusion device 12, the gripper 18 consists of a segmented high-grade carbon steel ring 8 and a number of leading edge portions 19. Each leading edge portion 19 has a number of integral serrations or teeth 20 on its outer surface 21 which are angled in the opposite direction to direction B. Thus, as pressure is exerted from direction B, the teeth 20 bite into the inner wall (not shown) of the pipe creating a gripping seal. When no longer required, the bladder seal 1 is deflated and the seal and gripper 18 would be pigged out of the pipe.

Although the present invention provides an adjustable seal for use in conjunction with pipeline plugs, use of the present invention is not solely restricted to this particular application. In addition, although preferred materials are discussed in the above description, it is possible to manufacture the invention using other materials, particularly in respect of the outer ring 2 and anti-extrusion device 12 which may be manufactured from a variety of plastics materials or metals, respectively.

These and other modifications and improvements may be made to the present invention without departing from the scope of the invention.

Claims (16)

1. CLAIMS: 1. An annular seal for sealing between the internal wall of a tube member and a cylindrical member disposed within the tube member, said seal comprising: a resilient annular outer member provided with an annular seal at its outer circumferential surface; and an inflatable annular inner member disposed adjacent to the inner circumferential surface of said annular outer member and provided with an inflation insert adapted to permit the passage of fluid for inflating said annular inner member.
2. 2. The annular seal of Claim 1, wherein said annular seal comprises a sealing member of material softer than the material of the annular outer member, the sealing member being disposed within a circumferential recess in the annular outer member.
3. 3. The annular seal of any preceding claim, wherein said inner member comprises a pair of opposing concave side walls, said side walls being adapted to concertina between a collapsed position when the inner member is deflated, and an expanded position when the inner member is inflated.
4. 4. The annular seal of Claim 3, wherein the inner member further comprises an inner wall and an outer wall joined by said side walls, whereby the inner and outer wall remain substantially parallel to each other when the inner member moves from the deflated state to the inflated state.
5. 5. The annular seal of any preceding claim, wherein the material of the inner member is resilient and has a lower stiffness than the material of the outer member.
6. 6. The annular seal of any preceding claim, further comprising a plurality of arcuate ring segments disposed at a first outer edge of said outer member, and a plurality of link members, each link member linking two adjacent ring segments.
7. 7. The annular seal of Claim 6, wherein each of said arcuate ring segments is provided with a plurality of detent portions on the outer circumferential surface thereof.
8. 8. The annular seal of Claim 7, wherein said detent portions are integrally formed with said arcuate ring segments.
9. 9. The annular seal of either Claim 7 or Claim 8, wherein said detent portions are disposed in a direction away from said first outer edge.
10. 10. The annular seal of any of Claims 6 to 9, wherein said arcuate ring segments and said link members are provided with apertures, said outer member is provided with threaded inserts and said arcuate ring segments and said link members are secured to said threaded inserts by threaded fasteners.
11. 11. The annular seal of any of Claims 6 to 10, wherein said arcuate ring segments and said link members are of a material of greater stiffness than the material of the outer member.
12. 12. The annular seal of Claim 11, wherein said arcuate ring segments and said link members are of metal.
13. 13. The annular seal of Claim 11, wherein said arcuate ring segments and said link members are of high-grade carbon steel and the outer member is of polyproylene.
14. 14. The annular seal of any of Claims 6 to 13, wherein said arcuate ring segments extend within a recess in the outer member over at least half the radial thickness of the outer member.
15. 15. The annular seal of Claim 14, wherein the respective cross-sectional profiles of said link members and said arcuate ring segments are such so as to permit relative movement in a circumferential direction but to prevent relative movement in a radial or axial direction.
16. 16. An annular seal as hereinbefore described and illustrated in the accompanying drawings.