GB2270729A

GB2270729A - Pipeline pig introducing apparatus

Info

Publication number: GB2270729A
Application number: GB9218250A
Authority: GB
Inventors: Walter Robert Suttie
Original assignee: CENTURY ASSOCIATES Ltd
Current assignee: CENTURY ASSOCIATES Ltd
Priority date: 1992-08-27
Filing date: 1992-08-27
Publication date: 1994-03-23
Also published as: GB9218250D0

Abstract

There is provided apparatus (10) for the introduction of a pipeline pig (20) into a pipeline at some location along the length of the pipeline, the apparatus including a carrier (18) for an inflatable pig body (20) in a deflated condition, means for introducing a part of said carrier into the pipeline to position said inflatable pig body within said pipeline, means (26, 30, 32) for inflating said inflatable pig body, and means 28, 34 for effecting the release of the inflated pig from said carrier. The means for effecting the release of the inflated pig from the carrier may be an overload release which is effective on the attainment of a pre-determined pressure in the inflated pig. Alternatively, the pig may be inflated with a predetermined volume of fluid and the means for effecting the release of the inflated pig may be manually operable mechanical means or may be effected by the re-establishment of a liquid or gas flow through the pipeline. The apparatus lends itself ideally for use with subsea pipelines, that is to say where the breaking of a pipeline at a flange to introduce a pig is not possible or is uneconomic. <IMAGE>

Description

Pipeline pig introducing apparatus The invention relates to pipeline pig introducing apparatus; that is to say to apparatus whereby a device can be introduced into a pipeline to be propelled along the pipeline by a liquid or gas flow to clean its walls or to swab and purge the pipeline, for example. Pipeline pigs used for such a purpose have generally been made of a deformable foam elastomer or of a gelatinous material so as to be capable of passing through restrictive fittings, such as valves, and have generally been introduced into a pipeline through an open end.

According to one aspect of the invention, there is provided apparatus for the introduction of a pipeline pig into a pipeline at some location along the length of the pipeline, the apparatus including a carrier for an inflatable pig body in a deflated condition, means for introducing a part of said carrier into the pipeline to position said inflatable pig body within said pipeline, means for inflating said inflatable pig body, and means for effecting the release of the inflated pig from said carrier.

The carrier for the inflatable pig body may be of generally cylindrical form and may extend into the pipeline through a fluid tight gland. The carrier may be provided with a cavity in which the inflatable pig body can be located in deflated condition.

The means for inflating said inflatable pig body may include a one-way valve which remains associated with the inflated pig after the latter has been released from the carrier. The fluid used to inflate the pig body may be a urethane or polyurethane foam material which reacts after inflation of the pig to form a deformable solid plug member bounded by the material forming the pig body. Alternatively, the inflating fluid may be a self supporting gelatinous substance or other hygroscopic material suitable for use in dry gas pipelines.

The means for effecting the release of the inflated pig from the carrier may be an overload release which is effective on the attainment of a pre-determined pressure in the inflated pig.

Alternatively, the pig may be inflated with a predetermined volume of fluid and the means for effecting the release of the inflated pig may be a manually operable mechanical means or may be effected by the re-establishment of a liquid or gas flow through the pipeline.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which:- Figure 1 is a diagrammatic view of apparatus embodying the invention for fitment to a pipeline, Figure 2 is a sectional view on the line 2-2 in Figure 1, and Figures 3 to 5 are views similar to Figure 1 and illustrating successive stages in the inflation of a pipeline pig within the pipeline.

Referring now to Figure 1, apparatus there illustrated for the introduction of a pipeline pig into a pipeline is generally indicated 10 and is shown about to be mounted on a branch pipe 12 projecting from the pipeline at some location along its length. (It will be understood that an isolation valve 14 upstream of said branch pipe will have been closed to enable the apparatus to be mounted on the branch pipe in communication with the flow passage through the pipeline).

The apparatus 10 comprises a flanged cylndrical body 16 which is to be bolted to the flange of the branch pipe and a carrier 18 for an inflatable pig body 20 in a deflated condition, the carrier being slidably mounted in said body 16. The carrier, being of generally cylindrical form, extends through a fluid-tight gland 22 at an upper end of the body 16, and is rotatable in said body. A lower part of the carrier is provided with a cavity 24 in which a pig body in deflated condition can be located.

The apparatus also includes means for inflating the inflatable pig body, said means including a flow line 26 extending axially through the upper part of the carrier with connecting means 28 at a lower end of said flow line for connection to a neck portion of the inflatable pig body located in the cavity 24. A flexible conduit 30 connected to the upper end of said flow line communicates, via a manually operable valve 32, with a source of fluid under pressure for inflating the pig. The connecting means 28 for connection to the neck portion of the inflatable pig are releasable from the pig on the attainment of a pre-determined pressure in the inflated pig. A one-way valve 34 is located in the neck portion of the inflatable pig and remains associated with the inflated pig after the connecting means 28 have been released therefrom.

In use of the apparatus, when it is desired to introduce a pipeline pig into the pipeline, the carrier 18, with a pig body in deflated condition in the cavity 24, is advanced to the position shown in Figure 3, with the cavity facing downstream of the pipeline. As fluid under pressure is then admitted to said pig body, the latter becomes released from the cavity 24 and begins to expand to fill the available cross sectional space within the pipeline as shown in Figure 4. Having filled the cross sectional space within the pipeline, continued inflation of the pig body will cause it to assume an elogate shape, as shown in Figure 5.

The pressure of the fluid within the pig when it has assumed a pre-determined length is such that this constitutes an overload release for effecting the release of the inflated pig from the carrier.

That is to say, the pressure of the fluid being forced through the connecting means 28 into the neck portion of the inflated pig body causes said neck portion to break free. (This can be arranged to be either as a result of a tearing action of the neck portion of the pig body above the one way valve 34 or by the overloading of a mechanical clamping means by which the neck portion has been secured to the connecting means 28).

The fluid which has been used to inflate the pig body has been a material which reacts after inflation of the pig to form a deformable solid plug member bounded by the elastomeric material forming the pig body.

When the inflated pig has become released from the carrier, the apparatus can be extracted from the pipeline and the branch pipe re-capped. The isolation valve 14 will then be re-opened so that the flow of fluid or gas along the pipeline will propel the inflated pig whatever its purpose, be this to swab the walls of the pipeline or as a barrier to separate different fluids conveyed simultaneously through the pipeline for example.

Thus there is provided easily operable apparatus for the introduction of a pipeline pig into a pipeline at some location along the length of the pipeline. The apparatus lends itself ideally for use with subsea pipelines, that is to say where the breaking of a pipeline at a flange to introduce a pig is not possible or is uneconomic. The simple operation of the apparatus can quite well be carried out by divers or from the surface.

Various modifications may be made and it will be understood that other fluids may be used for inflating the pig body, for example the self supporting gelatinous substance previously used for the production of pipeline pigs.

It is not essential for the pressure of the fluid being forced through the connecting means 28 into the neck portion of the inflated pig body to cause the neck portion to break free from the carrier.

Indeed, in some ways it may be preferable for the pig body to be inflated with a pre-determined volume of fluid and for the means for effecting the release of the inflated pig to be a manually operable mechanical means, that is to say operable externally of the pipeline. Alternatively, the release of the inflated pig could be effected by the re-establishment of a liquid or gas flow through the pipeline, resulting either in a tearing action of the neck portion of the pig body above the one way valve 34 or the overloading of a mechanical clamping means by which the neck portion has been secured to the connecting means 28.

It is not essential for the apparatus to be mounted on a branch pipe at some intermediate location along the length of a pipeline. It could be connected to a closed pipe end, be this a flanged or capped pipe end.

Claims

CLAIMS:

1. Apparatus for the introduction of a pipeline pig into e pipeline at some location along the length of the pipeline, the apparatus including a carrier for an inflatable pig body in a deflated condition, means for introducing a part of said carrier into the pipeline to position said inflatable pig body within said pipeline, means for inflating said inflatable pig body, and means for effecting the release of the inflated pig from said carrier.

2. Apparatus according to claim 1 wherein the carrier for the inflatable pig body is of generally cylindrical form and is extensible into the pipeline through a fluid tight gland.

3 Apparatus according to claim 1 or claim 2 wherein the carrier includes a cavity in which the inflatable pig body can be located in deflated condition.

4. Apparatus according to any of the above claims wherein the means for inflating said inflatable pig body includes a one-way valve which is capable of remaining associated with the inflated pig after the pig has been released from the carrier.

5. Apparatus according to any of the above claims wherein the means for effecting the release of the inflated pig from the carrier include overload release means which are operable to release the pig on the attainment of a pre-determined pressure in the inflated pig.

6. Apparatus according to any one of claims 1 to 4 wherein the means for effecting the release of the inflated pig include manually operable mechanical means for releasing the pig from the carrier.

7. Apparatus for the introduction of a pipeline pig into a pipeline substantially as any one embodiment herein described with reference to figures 1 to 5 of the accompanying drawings.

8. A method for introducing a pipeline pig into a pipeline including the steps of: (i) introducing into the pipeline an inflatable pig body in a deflated condition mounted on a carrier, (li) inflating the inflatable pig body, (iii) effecting release of the inflated pig from said carrier.

9. A method of introducing a pipeline pig into a pipeline according to claim 8 further including the step of inflating the inflatable pig body with a material which reacts after inflation of the pig to form a deformable solid plug member bounded by the material forming the pig body.

10. A method according to claim 8 or claim 9 wherein the step of releasing the inflated pig from the carrier is performed when the pig has been inflated to a predetermined pressure.