WO1995025925A1

WO1995025925A1 - A pipeline sealing unit and a method thereof

Info

Publication number: WO1995025925A1
Application number: PCT/GB1995/000628
Authority: WO
Inventors: Walter Rodaway
Original assignee: Avon Lippiatt Hobbs (Contracting) Limited
Priority date: 1994-03-23
Filing date: 1995-03-22
Publication date: 1995-09-28
Also published as: GB9405719D0; GB2287763B; GB2287763A

Abstract

The pipeline sealing unit (1) has a platform (9) on which an arm (10) is pivotally mounted. At the free end of the arm (10) there is a nozzle (14) which is shaped so as to be inserted at least partially within a joint to be sealed. A camera (22) is mounted on the arm (10) and is used to position the nozzle (14) accurately within the joint. A service tube (5) is also provided which connects the platform (9) to power and sealant supplies. The sealing unit (1) is used to repair pipeline joints by injecting low-viscosity sealants into the joints. Once the sealing unit (1) is inserted into a pipeline it is capable of treating or repairing more than one pipeline joint thereby significantly reducing the cost and inconvenience of large sections of pipeline being excavated. Moreover, the sealing unit is intended for use whilst the pipeline remains operational thereby limiting any inconvenience to users of the service .

Description

A PIPELINE SEALING UNIT AND A METHOD THEREOF

The present invention relates to a pipeline sealing unit and a method thereof for use in the treatment, repair and maintenance of pipeline joints and particularly but not exclusively gas mains.

Conventional methods of preventing leakage from joints in gas mains have involved either external or internal treatment . Internal methods have the advantage that they offer the treatment of a number of joints from a single excavation, reducing excavation and reinstatement costs and the general above-ground disruption associated with external repair methods. The development of low-viscosity anaerobic sealants has led to progress in the internal treatment of the joint materials giving a more permanent solution than that offered by glycol spraying. In GB2247062A an internal method of treatment is described in which a rodding unit is used to deploy a combined joint locator and spray head into the joint area which is then sprayed with sealant . The fluid is absorbed by the porous yarn where, on curing, it forms an impermeable matrix.

One of the disadvantages of this known method is that relatively high velocity jets of fluid are directed at the top quadrant of the joint. The aim is to thoroughly wet this region so that some of the sealant is absorbed in the top quadrant area due to capillary action, whilst the remaining sealant treats the rest of the joint by gravity feed, that is the remaining sealant is drawn down around the joint by the action of gravity. To ensure adequate wetting of the joint the spraying head is traversed to give 'blanket' coverage. This method results in a considerable waste of sealant which falls into the main as droplets or atomizes and can in certain conditions be carried in the gas stream. The consequences of these effects can be detrimental when the liquid cures, in that it can form a partial blockage in the main or contaminate plant downstream.

The present invention addresses the problems identified above with reference to the prior art and seeks to provide a pipeline sealing unit and method thereof which enables the treatment of a number of joints from a single excavation; which is more economical in its use of sealant whilst still ensuring an effective treatment of pipeline joints and which reduces the problems of sealant being carried in the fluid flowing in the pipeline.

The present invention therefore provides a pipeline sealing unit comprising a platform having an arm at the free end of which is a nozzle through which sealant is delivered and joint detection means for detecting the presence of a joint in the pipeline immediately adjacent the nozzle whereby sealant may be injected into the joint. In this way a pipeline may have its joints sealed without interruption of the fluid supply and in a way which reduces the problems of sealant being carried in the fluid.

Preferably, the nozzle has a predetermined geometry to enable the nozzle to be inserted into a gap located at the joint and there is further provided an actuator for moving the arm between a rest position and an injection position. In this way exact location of the nozzle in the joint may be achieved thus ensuring the sealant is efficiently injected into the joint. In a preferred embodiment the joint detection means is in the form of a television camera which is mounted on the arm.

In a further aspect the present invention provides a method of sealing joints in a pipeline comprising the steps of moving a platform along the inside of a pipeline; detecting the presence of a joint in the pipeline immediately adjacent a nozzle mounted on an arm on the platform; and injecting sealant through the nozzle into the joint.

Preferably, the sealant is injected through the nozzle into the joint in predetermined pulses.

It will be understood that reference to a pipeline herein is reference to any pipes or conduits conveying fluids such as gas or water for example.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic view, partially in cross-section, of a pipeline sealing unit in accordance with the present invention in use in a gas main and associated ground level control apparatus;

Figure 2 is an enlarged diagrammatic view, partially in cross-section, of the gas main sealing unit of Figure 1 in position at a joint of the gas main; and Figure 3 is a schematic view of the ground level control apparatus of Figure 1.

In Figure 1 a pipeline sealing unit 1 is shown both within a gas main 2 at a joint 3 and also, separately, in the process of entering the gas main 2. The sealing unit 1 is connected to ground level control apparatus 4 by means of a service and rodding tube 5.

The sealing unit 1 is shown in greater detail in Figure 2. The sealing unit 1 is formed of a head portion 6 on which a light 7 is mounted so as to illuminate the area about the sealing unit 1. The light may be focused providing a directional beam of light either ahead or above the sealing unit or the light may be unfocussed providing diffuse light surrounding the sealing unit 1. The light 7 may be powered by one or more batteries mounted in the head portion 6 or, as shown in Figure 2, the light 7 may be supplied with power via a cable 8 which extends through the sealing unit 1 to the service tube 5 and through the service tube 5 to the ground level control apparatus 4. Behind the head portion 6 is the main body 9, in the form of a platform, of the sealing unit 1. An arm 10 is pivotally mounted by means of a pin 11 to the main body 9. The arm 10 is hollow and has an upper portion 12 distant from the main body 9 which is offset by a connecting portion from a lower portion 13 which is connected to the main body 9 so as to form a crank- shaped member.

At the free end of the upper portion 12 a nozzle 14 is provided. The nozzle 14 is also hollow and is in communication with the passage within the arm 10. The nozzle 14 is shaped so as to slidingly fit within a gap or region formed between a shoulder of a first section of a conventional gas main and an edge of a second section of the conventional gas main at the joint 3. Hence, as seen in Figure 2, the nozzle 14 projects outwardly and upwardly from the upper portion 12 of the arm 10 and decreases in width towards its free end 15 at which is located a small opening. The nozzle 14 has a flat substantially vertical surface 16 for sliding engagement with the edge of the second section of the gas main. It will of course be appreciated that alternative selective geometries of the nozzle 14 could be implemented to enable the free end 15 of the nozzle 14 to project or be inserted into different shaped joints 3, when in use.

At the end of the arm 10 distant from the nozzle 14 a lug 17 is provided. The lug 17 is pivotally connected to the main body 9 by means of a pin 11, already mentioned. The end of_. the lug 17 distant from the pin 11 is connected to the rod 18 of an actuator 19. The rod 18 is connected to the lug 17 by means of a further pin 20 so as to enable relative pivotal movement between the lug 17 and the rod 18. The actuator 19 may be in the form of an hydraulic or pneumatic piston which causes movement of the rod 18 and thereby movement of the lug 17 and arm 10. The actuator 19 is connected to the ground level control apparatus 4 by means of control and power lines 8 and fluid line 21.

A miniature television camera 22 is mounted on the lower portion 13 of the arm 10. The camera 22 is arranged so that its line of sight is along the arm 10 towards the nozzle 14 and, by virtue of the crank- shape of the arm 10, the nozzle is clearly visible to the camera 22. The camera 22 is in communication with the ground level control apparatus 4 so that the camera images may be viewed at ground level. The camera 22 may be movable so that the whole of the joint 3 can be viewed.

The service and rodding tube 5 which is flexibly attached to the main body 9 contains all the control, power and fluid lines 8, 21 as well as any camera transmission lines so as to protect the lines from the environment in the gas main 2. The service tube 5 is also provided to move the head portion 6 and main body 9 along the gas main 2, it is conventional in design and includes rodding members 23 for enabling the movement of the sealing unit 1 and the service tube 5 along the gas main 2.

A method of sealing joints in gas a main will now be described with reference in particular to

Figures 1 and 3. The sealing unit 1 is inserted into a gas main 2 in a conventional manner by insertion through an angled entry fitting 24 with an isolating valve 25. This enables the sealing unit 1 to be inserted and used whilst gas is being supplied through the gas main 2 and thereby avoiding the inconvenience of the gas supply being halted for a considerable length of time. As may be seen, the head portion 6 is connected to the main body 9 by means of the power line 8 which is flexible and so the ease of insertion of the sealing unit 1 is improved because the head portion 6 is able to move relative to the main body 9. this also means that the entire length of the sealing unit 1 may be greater than the diagonal width of the gas main 2. As long as neither the head portion 6 nor the main body 9 is greater in length than the diagonal, the sealing unit 1 may still be inserted into the gas main 2 with ease.

Once the sealing unit 1 is within the gas main 2 and resting on the floor of the main, the sealing unit 1 is pushed along the gas main 2 either by hand or with the aid of a pushing unit 26. The pushing unit 26 is part of the ground level control apparatus 4 and is mounted on the service tube 5 to be fed into the gas main 2. The pushing unit 26 is ideally hydraulically or pneumatically operated and grips and pushes the service tube 5 into the gas main 2. A clutch (not shown) is provided to enable the pushing unit 26 to return to its original position after each pushing action without withdrawing that portion of the service tube 5 just pushed forward. It will be understood that the action of the pushing unit 26 may be reversed when it is desired to remove instead of insert the sealing unit 1 and service tube 5. The service tube 5, which is semi-rigid, is stored coiled on a reel 27 in a conventional manner. The service tube 5 stored on the reel 27 is also connected by means of a universal joint 28 to a management control unit 29, which will be discussed in detail later.

The arm 10 on the sealing unit 1 is in a rest position, shown in dashed lines in Figure 2, when the sealing unit 1 is moved along the gas main 2. In its rest position, the arm 10 is located in recesses 30 provided in the top of the main body 9 and the head portion 6. In this position the line of sight of the camera 22 is along the gas main 2 which is illuminated by the light 7. In this way an operator at ground level with the management control unit 29 is able to view the progress of the sealing unit 1 and identify the presence of a joint 3. The operator watches the progress of the sealing unit 1 on a screen 31 on a control console 32 of the management control unit 29. The control console 32 is connected to a camera and lighting processor 33 and from there via the services tube 5 to the camera 22 and light 7. The control console 32 is also connected to an actuator pump 34 and sealant pump 35 which pump fluid and sealant respectively to the actuator 19 and the nozzle 14.

Once a sealing unit 1 is immediately adjacent a joint 3 to be sealed the arm 10 is raised or retracted from its rest position by operation of the actuator 19 via the rod 18 on the lug 17 of the arm 10. By means of the camera 22 and the service tube 5 the sealing unit is pushed/pulled to align the nozzle 14 with the gap in the joint 3. As mentioned earlier, the nozzle 14 has a specific geometry to enable it to project or be inserted into the gap of a conventional gas main joint 3. Once in position, the free end 15 of the nozzle 14 and therefore the opening of the nozzle 14 is adjacent a corner of the joint 3. The sealant pump 35 is then actuated to pump a low viscosity, anaerobic sealant to the nozzle 14 so that it may be injected directly at the corner of the joint 3. Thus, sealant is injected directly into the top of the joint 3. Ideally, the sealant is injected in short, measured pulses with a predetermined time interval between each pulse. This enables the sealant to be absorbed by the yarn packing 36 in the joint 3. The sealant is also drawn down, around the joint 3, by the action of gravity from the injection point which is the top dead centre of the joint 3 so that the joint 3 is sealed about its periphery. In this way an exact amount of sealant can be delivered for a given size. In addition, the operator is.able to monitor the injection of the sealant by means of the camera 22 so that delivery of sealant can be halted if the sealant is seen to be emerging from the joint 3.

After injection of the sealant, the arm 10 is moved from the sealant delivery or injection position back to its rest position so that it may be moved to the next joint 3 in the gas main 2. With the apparatus and method described, a number of joints in a gas main or alternative pipeline can be sealed through a single access point. Moreover, the sealant is injected directly into the joint which reduces wastage of sealant, ensures that the joint is properly sealed and also reduces the risk of sealant being carried in the fluid stream to damage meters or contaminate plant downstream.

It will of course be understood that alternative arrangements of injecting devices could be utilised to inject the sealant directly into the pipeline joint in accordance with the present invention. For example, the arm 10 need not be hollow and instead the sealant may be delivered to the nozzle 14 by means of a separate sealant pipe. Also, the nozzle 14 may be detachable from the arm 10, so that different geometries of nozzle may be mounted on the arm 10 depending on the type of pipeline the sealing unit is to be used in. Moreover, the lug 17 need not be pivotally connected to the rod 18, instead the lug 17 may include a ramped surface against which the rod

18 abuts. These and further alternatives are envisaged in accordance with the present invention.

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Claims

1. A pipeline sealing unit comprising a platform having an arm at the free end of which is a nozzle through which sealant is delivered and joint detection means for detecting the presence of a joint in the pipeline immediately adjacent the nozzle whereby sealant may be injected into the joint.

2. A pipeline sealing unit as claimed in claim 1, wherein the nozzle has a predetermined geometry to enable the nozzle to be inserted into a gap located at the joint.

3. A pipeline sealing unit as claimed in either of claims 1 or 2, wherein there is further provided an actuator for moving the arm between a rest position and an injection position.

4. A pipeline sealing unit as claimed in claim

3, wherein the actuator is connected to the end of the arm distant from the nozzle.

5. A pipeline sealing unit as claimed in claim

4, wherein the actuator is an hydraulically or pneumatically driven actuator.

6. A pipeline sealing unit as claimed in any one of the preceding claims, wherein the joint detection means is in the form of a television camera.

7. A pipeline sealing unit as claimed in claim 6, wherein the television camera is mounted on the arm.

8. A pipeline sealing unit as claimed in either of claims 6 or 7, wherein there is further provided a lighting device mounted on the platform.

9. A pipeline sealing unit as claimed in any one of the preceding claims, wherein control means are provided for controlling the movement of the platform within the pipeline and the injection of sealant into the joint.

10. A pipeline sealing unit as claimed in any one of claims 3 to 5 and 9, wherein said control means includes actuator controlling means for controlling movement of the arm.

11. A pipeline sealing unit as claimed in any one of the preceding claims, wherein sealant delivery control means are provided for injecting the sealant into the joint in predetermined pulses.

12. A method of sealing joints in a pipeline comprising the steps of moving a platform along the inside of a pipeline; detecting the presence of a joint in the pipeline immediately adjacent a nozzle mounted on an arm on the platform; and injecting sealant through the nozzle into the joint.

13. A method as claimed in claim 12, wherein the nozzle is inserted into a gap in the joint prior to the sealant being injected into the joint.

14. A method as claimed in either of claims 12 or 13 , wherein the arm is movable between a rest position and an injection position such that when the platform is being moved within the pipeline the arm is in its rest position and once the presence of a joint is detected the arm is moved to its injection position.

15. A method as claimed in any one of claims 12 to 14, wherein the sealant is injected through the nozzle into the joint in predetermined pulses.