GB2383108A

GB2383108A - Pipe blocking device

Info

Publication number: GB2383108A
Application number: GB0126491A
Authority: GB
Inventors: Martyn James Smith; Ronald Alec Sewell
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-11-03
Filing date: 2001-11-03
Publication date: 2003-06-18
Also published as: GB0126491D0

Abstract

A device for establishing an environment of a required fluid inside a length of pipe, comprising two pipe blocking members adapted to block the interior of the pipe at respective spaced positions therealong, and means for introducing said fluid into the interior of the pipe between said blocking members, wherein each blocking member comprises a casing having a peripheral portion for engaging the pipe interior surface and containing a ring-like inflatable element, and a closure portion closing the space within said peripheral portion.

Description

Title: Pipe Blocking Device Description of Invention This invention relates to the establishment and maintenance of an environment of a required fluid in the interior of a length of pipe, conduit or the like (the term"pipe"will be used generically herein).

Such an environment might be required to be established and maintained inside a length of pipe to assist a welding operation being carried out on the pipe. For example where two lengths of pipe are required to be joined to one another, or a pipe is required to be joined to a pipe fitting, by butt-welding circumferentially of the pipe, the establishment of an atmosphere of inert gas inside the pipe in the region where welding is to take place assists the welding operation. Oxidation and notching of the root penetration weld bead is prevented or substantially prevented. The inert gas may be argon.

One way in which the required environment can be established and maintained inside a length of pipe is by disposing two members inside the pipe for blocking the pipe at required positions, and introducing the required fluid to the pipe interior between the blocking members. In one known apparatus, the blocking members each have comprised an inflatable bladder contained within a casing, inflation of the bladder expanding the casing until it is in firm contact with the inside surface of the pipe. The two blocking members, when thus caused to engage and block the pipe, define a region between them in which an atmosphere of inert gas can be maintained by introducing the inert gas, between the blocking members, at a rate corresponding to the rate at which it escapes through whatever opening exists by virtue of the operation which is being carried out on the pipe. One way in which inflation of the bladders of the blocking members and the admission of the inert gas to the space therebetween

has been achieved is by providing a supply pipe for the inert gas which extends between the blocking members for inflating the bladders thereof and has a relief valve which, after inflation of the bladders has been completed and the pressure therein and in the pipe rises, releases the inert gas into the space between the blocking members. A vent means in one or each of the blocking members prevents the pressure of inert gas therebetween rising above safe limits.

Whilst such a device performs satisfactorily, the configuration of the blocking members with the bladders therein is such that when inflated they are more or less of spherical configuration and thus occupy a significant length of pipe in their own right. In certain circumstances, this may be inconvenient.

Also under certain circumstances a more robust construction of blocking member might be desirable. It is broadly the object of the present invention to address these requirements.

According to one aspect of the invention, I provide a device for establishing an environment of a required fluid inside a length of pipe, comprising two pipe blocking members adapted to block the interior of the pipe at respective spaced positions therealong, and means for introducing said fluid into the interior of the pipe between said blocking members, wherein each blocking member comprises a casing having a peripheral portion for engaging the pipe interior surface and containing a ring-like inflatable element, and closure portion closing the space within said peripheral portion.

Preferably the ring-like inflatable element comprises an inner tube for a vehicle tyre. Such inner tubes are available in a wide range of sizes, ranging from those which are typically used for hand-propelled vehicles such as wheelbarrows and the like, through those typically used for motor scooters and motorcycles, to those typically used for cars and commercial vehicles. Whatever size they are, inner tubes are inexpensive and robust. Each blocking member occupies relatively little space in the direction lengthwise of the pipe,

and is able to accommodate a reasonable amount of deviation from true roundness of the pipe interior.

The peripheral portion of the casing is preferably annular with an opening through which the inflation/deflation stem of the inner tube extends to accommodate an inner tube of appropriate size.

To enable it to conform to the internal cross-sectional shape of a pipe, the casing requires to be made of a flexible material which must of course be substantially impermeable in order that the required fluid can be maintained inside the pipe between the blocking members. Such a material preferably is a woven fabric material having an impermeable coating, e. g. of plastics or rubber, which is capable of being stitched to form the casing and is substantially non-stretchable so that the inner tube in the peripheral portion of the casing is constrained against over-inflation. One suitable such material is a polyurethane-coated woven nylon material.

Preferably the inner tubes of the two blocking members are connected to one another for inflation/deflation together from a common fluid supply. To this end the device preferably comprises a pipe extending between the blocking members and having connections to the respective inflatable elements thereof.

Preferably such a pipe extends substantially centrally through the central wall portions to aid in the stability and hence sealability of the blocking members.

Preferably such a connecting pipe is also provided with valve means for releasing the inflation fluid into the interior space of the pipe between the blocking members. Such valve means may be a relief valve, such that when fluid is supplied to the pipe it initially inflates the inner tubes of the blocking members until they are fully inflated so that the blocking members effectively block the pipe, whereafter further supply of the fluid causes an increase in pressure so that the fluid is released by the relief valve into the space between the blocking members.

One or each of the blocking members preferably includes vent means for releasing fluid from the space between the blocking members. Such vent means may simply comprise an aperture of known size.

The invention will now be described by way of example with reference to the accompanying drawing, which is a perspective view, partly broken away, of a device in accordance with the invention, in use within a pipe.

Referring to the drawing, it shows a length of pipe indicated generally at 10, which comprises two portions 11,12 in end-to-end relationship joined by a circumferential weld 13 which is shown as being partly completed. In the interior of the pipe there are respective blocking members indicated generally at 14,15, one on each side of the weld at sufficient distance therefrom so as not to be affected by welding heat.

The blocking member 14, which is shown as partially broken away, comprises a casing indicated generally at 16 which is made from appropriatelyshaped pieces of polyurethane-coated nylon fabric, sewn together to the configuration described. The casing 16 comprises a peripheral portion 17 which is generally toroidal in configuration defining an annular volume in which is accommodated a ring-like inflatable element namely an inner tube 18 such as is used in vehicle tyres. The casing further comprises a closure portion 20 which closes off the central area of the casing, within the toroidal peripheral portion 17. The closure portion 20 comprises two spaced walls 20a, 20b.

The blocking member 15 is of the same construction as the blocking member 14: thus it has a casing with peripheral portion 21 containing an inner tube and spaced walls 22a, b of the closure portion22. The two blocking members 14,15 are connected by a pipe system 24 which comprises a T-piece 25 extending through a grommet 30 in each of the spaced walls 20a, b of the closure portion 20 of the blocking member 14. The grommets 30 allow for slight longitudinal movement of the T-piece 25 within the blocking member 14

so that the blocking member 14 is able to align itself to provide a more z

effective seal with the pipe 10. The T-piece 25 located within the spaced walls 20a, b of the closure portion 20 provides for connection of the pipe system 24 to the inflation stem 19 of the inner tube 18 of the blocking member 14. Similarly, located within the spaced walls 22a, b of the closure portion 22 of the blocking member 15 is a T-piece 50 which has the same fittings as T-piece 25 and hence also allows for the connection of the pipe system 24 to the inflation stem 23 of the inner tube 18 of the blocking member 15.

At the opposite ends of each of the T-pieces 25,50 there are provided respective releasable gas-tight connectors 70. The connectors 70, which face each other between the blocking members 14,15, allow for connection of blocking member 14 to blocking member 15 via a centrally extending detachable pipe 60, being a flexible plastics or rubber hose. Connected to the pipe 60 and to the T-piece 50 is a further T-piece 27 which provides for the connection of a pressure relief valve 28 which is openable to release fluid into the space between the blocking members 14,15 when the pressure in the pipe system 24 (and the inner tubes of the blocking members) exceeds a predetermined value. The outwardly facing releasable gas-tight connector 70 attached to the T-piece 25 allows for connection of the pipe system 24 to a fluid supply pipe 26. Inserted into the corresponding releasable gas-tight connector 70 of the T-piece 50 is a pipe plug 40 which stops the fluid from escaping into the interior space of the pipe 10 beyond the blocking member 15 and hence retains the pressure within the pipe system 24.

As herein firstly referred to, a device as above described is primarily to be used for establishing an atmosphere of an inert gas inside a pipe where welding is to be carried out on the pipe. The device is used by disposing it inside the pipe, with the inner tubes of the blocking members deflated, and with the blocking members at the required positions either side of the region where the welding is to take place. Then the required inert gas, e. g. argon, is supplied through the pipe 26 to inflate the inner tubes and cause the blocking members

respectively to block the pipe. When this inflation has occurred and the inner tubes can expand no further owing to being restrained by the casings of the blocking members, an increase in pressure of the supplied gas will cause the relief valve 28 to open and release the gas into the space between the blocking members.

Also visible in the drawing is a vent means provided for each of the blocking members 14, 15. Each vent means comprises a respective grommet 31 in each wall of the closure portion 20 with a pipe 32, being a flexible plastics or rubber hose, connecting said grommets 31. Attached to the exterior grommet 31 of both blocking members 14,15 is a fitting 33, which is a vehicle tyre valve stem.

The threaded end portion of this allows for the fitting of a closure cap, or for the attachment of measuring apparatus to either end of the pipe blocking device (e. g. a probe to sample the inert gas for analysis). One vent means would be left open for releasing excess gas from the interior space. Handling loops 34,35 are also shown on the blocking member 14, to assist in positioning the blocking member as required within the pipe. The pipe 24 is detachable from the blocking members 14,15 so that different sized blocking members can be used when joining pipes of differing diameters.

An alternative method of use of the pipe blocking system would be to swap the pipe plug 40 with the relief valve 28. This allows the blocking members 14,15 to be inflated to a predetermined pressure whilst the inert gas is supplied via one or both of the fittings 33.

After use of the device, the supply of inert gas to it is disconnected or turned off and the inner tubes of the blocking members deflated. Then the device can simply be withdrawn axially from the interior of the pipe.

In the present specification "comprises" means "includes or consists of and "comprising" means "including or consisting of'.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in

terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A device for establishing an environment of a required fluid inside a length of pipe, comprising two pipe blocking members adapted to block the interior of the pipe at respective spaced positions therealong, and means for introducing said fluid into the interior of the pipe between said blocking members, wherein each blocking member comprises a casing having a peripheral portion for engaging the pipe interior surface and containing a ring- like inflatable element, and a closure portion closing the space within said peripheral portion.

2. A device according to Claim 1 wherein the ring-like inflatable element comprises an inner tube.

3. A device according to Claim 2 wherein the peripheral portion of the casing is annular with an opening through which the inflation/deflation stem of the inner tube extends.

4. A device according to Claim 3 wherein the casing of each blocking member is of a woven fabric material having a substantially impermeable coating.

5. A device according to any one of the preceding claims wherein the inflatable elements of the two blocking members are connected to one another

for inflation/deflation together from a common fluid supply. t

6. A device according to Claim 5 wherein the device comprises a pipe extending between the blocking members and having connections to the respective inflatable elements thereof.

7. A device according to Claim 6 wherein said pipe extends substantially centrally through the closure portions of the blocking members.

8. A device according to Claim 6 or Claim 7 wherein said pipe is also provided with valve means for releasing the inflation fluid into the interior space of the pipe between the blocking members.

9. A device according to Claim 8 wherein said valve means is a relief valve.

10. A device according to any one of the preceding claims wherein one or each of the blocking members preferably includes vent means for releasing fluid from the space between the blocking members.

11. A device according to any one of the preceding claims wherein said Z7, closure portion of each blocking member comprises two wall portions spaced lengthways of the pipe.

12. A device according to claim 11 as appendent to claim 7 wherein said wall portions are movable axially of the pipe.

13. A device according to claim 6 or any claim appendent thereto wherein said pipe includes releasable connections between respective portions thereof.

14. A device substantially as hereinbefore described with reference to the

accompanying drawings. tl : l c

15. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.