AU7080196A - Linestopping system - Google Patents

Description

TITLE

LINESTOPPING SYSTEM DESCRIPTION OF THE INVENTION

The present invention relates to a linestopping system for stopping the flow of fluids or

gases in a section of a pipe.

FIELD OF THE INVENTION

Repair and replacement of pipes, whether in an emergency or maintenance situation, is

a financial liability for service providers such as Utilities and Processors. Linestopping

presently involves removing an approximately circular section of approximately the same radius as the pipe from an upper portion of the pipe. Removal of the section can

seriously weaken the pipe structure, requiring reinforcement or strapping of the pipe.

This reinforcement may take the form of pipe encasing metal sleeves secured to the pipe.

Additionally, concrete reinforcing is often used. Considerable human and consumable resources are required to ensure adequate reinforcing is provided.

Once the pipe is reinforced, the process of line stopping employed hitherto involves several stages. The first stage is to attach an upwardly protruding branch connection to the pipe, such that the circumference of the aperture caused by removing the section is enclosed. The support section and the associated line stopper insertion apparatus is then

attached to the protruding connection via a flange. The third stage of the operation involves insertion of the linestopper at an angle approximately ninety degrees to the direction of flow through the pipe. The linestopper is inserted into the pipe, by way of a linestopper insertion apparatus. Where the line stopper is a rubber line stopper, it is

forced through the aperture and deforms to seal around the internal circumference of the

pipe. The length of the rubber line stopper is limited to the diameter of the aperture. Alternatively, where the line stopper employs a solid hinged rubber seated disc to seal

the pipe, the disc is positioned such that the plane of the disc is at an angle approximately

ninety degrees to the direction of flow through the pipe. Both these methods have

limitations, in addition to the time and cost liabilities previously discussed. These

limitations include the physical size of the equipment, weakening of the pipe to be

linestopped and little or no capability for the equipment to deal with a range of pipe sizes.

Further, these methods are only effective when used with pipes having a smooth interior

surface. Any debris or irregularities on the inside of the pipe greatly reduce the

effectiveness of previously known linestopping devices. In addition, these methods result

in the application of large forces onto the pipeline, which usually cause weakening.

Further these methods do not cater for the flow of fluid to continue around the section of

pipe to be repaired or replaced.

One method for dealing with line stopping, used predominantly in the petroleum industry, is to insert steel packers with a rubber jacket within the pipe. The rubber jacket

is arranged such that a seal can be produced between the pipe and the packer by inflating

the rubber jacket. These packers are inflexible and they have to be custom made for each

application. They are usuaUy used in very high pressure applications. Other main

disadvantages of this method are the requirement to access one end of the pipe and the interruption of the flow.

SUMMARY OF THE INVENTION

The present invention seeks to, at least in part, overcome some or all of the problems of

the prior art outlined above.

According to one aspect of the present invention there is provided a linestopping system

for pipes characterised by first and second linestopping means, each linestopping means

including an inflatable plug, an inflation means and an insertion means, first and second

branch pipe supports each having an apertured flange with a pipe section mounted

thereon at an acute angle, each pipe section containing a valve wherein, in use, the pipe

supports are disposed on a pipe in spaced apart locations with the pipe sections facing

in opposite directions such that upon apertures being cut in the pipe at the pipe supports

inflatable plugs of respective line stopping means may be inserted by the insertion means

through the apertures in the pipe and subsequently inflated by the inflation means so as

to seal off a section of the pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the

accompanying figures in which :-

Figure 1 represents a schematic side view of a linestopping system attached to a pipe;

Figure 2 shows a linestopping plug partially inserted into the pipe in accordance with the

present invention; Figure 3 shows the linestopping plug inserted into the pipe and inflated in accordance

with the present invention;

Figure 4 shows a cross section of the linestopping plug accordance with the present invention;

Figure 5 shows a cross section of the insertion device in accordance with the present

invention;

Figure 6 shows a cross section of the insertion device in a second position in accordance

with the present invention; and

Figure 7 shows two linestopping system as shown in Figure 3 inserted into the pipe and

inflated in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In Figures 1, 2 and 3 there is shown a linestopping system 10. The linestopping system

10 includes a branch pipe support 20, an insertion apparatus 30, a linestopping plug 50, an insertion push rod 70 and a pumping means 90.

The linestopping system 10 may be attached to a pipe 12 for the stopping of the flow of

a fluid in a pipe 12 such as a water supply pipe.

The branch pipe support 20 includes a curved apertured flange panel 22 substantially the

same or slightly larger in diameter than the outside diameter of the pipe 12 to which it

is to be attached. The branch pipe support 20 also includes a pipe section 24 which is

attached to the flange panel 22 at a first end and has a reinforced connection flange 26 at a second end. The connection flange 26 includes a valve 28 which allows the branch support pipe 20 to be sealed off so as to prevent fluid loss from the pipe 12. The connection flange 26 may include apertures for attachment means such as nuts and bolts to enable the insertion apparatus 30 to be securely and releasably attached.

The pipe section 24 is joined to the flange panel 22 such that the centre line of the pipe

section 24 forms an angle of between 30 and 50 degrees, preferably between 35 and 45

degrees, for example, about 40 degrees to the flange panel 24.

Once the flange panel 22 is mounted to the pipe 12, an aperture is cut in the pipe 12 by any convenient cutter means member in the pipe section 24.

The insertion apparatus 30 includes an insertion pipe 32, an insertion mechanism 34 and

a number of bypass pipe connectors 36.

The insertion pipe 32 has a lower end 38 and an upper end 40, the lower end 38 includes

a connection flange 42 and at least one bypass pipe connectors 36. The upper end 40 of the insertion pipe 32 includes a connection flange 43. The upper end of the insertion pipe

32 also includes a number of valves 33 as seen in Figures 5 and 6. The valves 33 may

be used to release air from the insertion pipe 32 when the valve 28 is opened. The

connection flange 42 attaches to the connection flange 26 in use, thus joining the insertion apparatus 30 to the branch pipe support 20. The insertion mechanism 34 is attached to the upper end 40 of the insertion pipe 32 at the

connection flange 43. The insertion mechanism 34 holds and inserts the push rod 70

during the insertion of the plug 50 into the pipe 12. The insertion mechanism 34 is described in more detail below.

The push rod 70 is attached to the plug 50. The push rod 70 includes a hollow tube 72

which the clamping means 44 and 46 grip and push into the pipe 12 using the jacking

means 48. The plug 50 may also be withdrawn using the push rod 70.

The tube 72 is hollow, and may be between 3 and 7 metres long such as 4 to 6 metres

long, and includes a set of attachments 73 at the upper end for pressurised fluid to be fed

into the tube 72. A hose 74 also runs down the middle of the tube 72 to feed pressurised

fluid to the plug 50. Further, the tube 72 incoφorates attachments at its lower end so that

pressurised fluid may be fed into the upper end attachment 73 through to the lower end

of the tube 72 and then fed into the plug 50 as seen in Figures 5 and 6.

The pressurised fluid is supplied by a fluid supplying means 90. The fluid supplying means 90 supplies fluid at two pressure levels. The lower pressure level fluid is fed into

the tube 72 by hose 92 through attachment 73 for use in inflating the plug 50. The higher

pressure fluid is fed along hose 94 and into a hose 74 in the tube 72 through another

attachment 73 as seen in Figure 1 and 2. In Figure 4 there is shown a plug 50. The plug 50 includes a nose cone 52, a balloon 54

and a base plug 56. The balloon 54 is sealingly attached to the nose cone 52 and the base

plug 56 such that the balloon 54 may expand to a diameter of up to 3 times the diameter of the nose cone 52 and the base plug 56, as can be seen in Figure 3.

The nose cone 52 includes a plurality of apertures 58. The apertures 58 are located on

the side of the nose cone 52 which is lowermost when the nose cone is inserted into the

pipe 12. Each aperture 58 is connected to an inlet pipe 60. The inlet pipes 60 join

together and connect to a single jet hose 62. The jet hose 62 runs through the length of

the plug 50 to the interior of base plug 56. The jet hose 62 is sealingly connected to the

base plug 56 and the jet hose 62 exits the base plug 56 and connects to the base of the

tube 72 of the push rod 70. The jet hose 62 enters the base of the tube 72 and connects

to the hose 74 which continues up the inside of the tube 72 until it reaches the end where

it exits the tube 72 and connects to a fluid supplying means 90 as seen in Figure 1 and

5.

The plug 50 is inflated by a fluid, typically water, being pumped into an interior cavity

64 of the plug 50 by the fluid supplying means 90. The pressure of the fluid causes the

plug 50 to inflate and increase in diameter. The fluid is fed into the cavity 64 of the plug

50 from an inflation pipe 66. The inflation pipe 66 feeds the pressurised fluid from the

interior of the tube 72 into a connection 68 in the base plug 56. The balloon 54 is constructed from an outer cover of flexible soft material 80, such as rubber, and an interior of resilient strands 82 woven around the interior of the material

80. The material 80 is between 20 and 60 mm, for example, 40mm thick.

The plug 50 is designed to fit snugly inside the insertion pipe 32.

The construction of the balloon 54 allows the balloon 54 to expand, such as up to three

times the original diameter, while having the properties of a soft deformable outer skin

and a firm inner core which can withstand internal pressures sufficient to inflate the

balloon 54 in the interior of a pipe 12 in which pressurised fluid is flowing.

The base plug 56 incorporates an attachment means 84 which allows the push rod 70 to be connected to the plug 50. The attachment means forms a joint 86 which allows the

plug 50 to be hingedly attached to the push rod 70 allowing the plug 50 to align itself and

be substantially in longitudinal alignment with the pipe 12 as can be seen in Figure 1, 2 and 3.

Figures 5 and 6 shows a cross section of the insertion device 34 attached to the insertion

pipe 32, the push rod 72 and the base plug 56 of the plug 50. The insertion device 34 includes an insertion support 35. The first clamping means 44, second clamping means

46 and jacking means 48 are attached to the insertion support 35.

The first clamping means 44 and the second clamping means 46 each include a set of hydraulic clamps 45. Each hydraulic clamp 45 includes a gripping surface 47.

The first clamping means 44 are fixedly attached to a recess in the insertion support 35. The second clamping means 46 are fixedly attached to the jacking means 48. The jacking

means 48 moves the second clamping means 46 between a first position shown in Figure

5 and a second position shown in Figure 6.

The insertion device 34 may include a sealing mechanism to stop any leakage of fluid

from around the tube 72.

To move the push rod 70 into the pipe 12, the following sequence of operation is

performed.

The first clamping means 44 engages and holds the tube 72 of push rod 70 in position while the jacking means 48 moves the second clamping means 46 to the second position

as seen in Figure 6. The second clamping means 46 then engage the tube 72 holding it immovably with respect to the second clamping means 46. The first clamping means 44 is then disengaged from the tube 72. The jacking means 48 then moves the second

clamping means 46 and therefore the tube 72 towards the first clamping means 44, to the

first position as shown in Figure 5.

This operation is repeated to move the push rod 70 and thus the plug 50 into the pipe 12. By reversing the aforementioned procedure the push rod 70 and plug 50 may be

withdrawn from the pipe 12 back into the insertion pipe 32. This operation is known as

'Hand over Hand' and allows the insertion apparatus 34 to insert the plug 50 into a live or pressurised pipe 12 in which there may be fluid flowing under a considerable pressure.

The clamping means 44 and 46 allows the tube 72 and plug 50 to be firmly and securely

located with respect to the aperture in the pipe 12. The hand over hand method provides

a secure grip and allows the plug 50 to be removed from the pipe 12 even as flow in the

pipe 12 applies pressure in the upstream side 14 of the pipe 12.

In Figure 7 there is shown two linestopping systems 10a and 10b used to block off a

section of a pipe 12 that has been damaged. The plugs 50, when inserted allow a

damaged section 100 of the pipe 12 to be isolated. The flow of fluid in the pipe is able

to be maintained by diverting the fluid out of the linestopping system 10a on the

upstream side of the damaged section 100 through bypass pipe connector 36 into bypass

pipe 102. To maintain an adequate flow of fluid through the bypass pipe 102 a pump 104 can be situated along the pipe 102.

The preferred embodiment and an example of use is described as follows.

In use, to stop the flow of fluid in a pipe 12 the following procedure is employed.

The branch support pipe 20 is welded or otherwise permanently attached to a section of

a pipe 12 in an upstream position 14 of a section of the pipe 12 to which flow is to be stopped. The branch support pipe 20 is situated in a position at the top of the pipe 12, that is if the pipe is looked at in cross section the centre line of the pipe 24 would be in a substantially twelve o'clock position.

The branch support pipe 20 has a pipe section 24 which is at an angle of between 30 and

50 degrees, for example 40 degrees to the angle of the centre line of the pipe 12. The

angle of 40 degrees provides the plug 50 with an angle of entry that allows the nose cone

52 to slide across the bottom the pipe 12 at a reduced friction force than if the angle was higher. Further the entrance angle of 40 degrees from the centreline of the pipe 12

reduces the overall height of the linestopping system 10 when in use.

A cutting device in a substantially watertight housing may be sealingly attached to the branch support pipe 20 and the valve 28 is opened. The cutting device enters the branch

support pipe 20 and cuts a section of the pipe 12 out. The valve 28 is then sealed and the

housing and cutting device are removed. The valve 28 may be in the form of a sluice gate.

The insertion apparatus 30 is then releasably and sealingly attached to the branch support

pipe 20. The insertion apparatus 30 has the plug 50 attached to the push rod 70 situated snugly inside the pipe as can be seen in Figure 1. The valve 28 is then opened and the

insertion apparatus 30 is used to move the push rod 70 toward the pipe 12, which thereby causes the plug 50 to be inserted into the pipe 12 as can be seen in Figure 2. When the plug 50 is inserted into the pipe 12 it is then inflated as seen in Figure 3. The inflation

of the plug 50 causes the flow in the pipe 12 to stop.

To keep the fluid flowing in a pipe 12, linestopping systems 10a and 10b may be

employed at an upstream and downstream position of, for example, a break in the pipe

12, as can be seen from Figure 7. Once the linestopping systems 10a and 10b are in

position the flow in the bypass pipe connectors 36 may be started by opening the valves

37. The fluid in the pipe 12 may then flow through bypass pipe 102 without interruption

around the section of pipe 12 to be isolated. The flow of the fluid in the bypass pipe 102

may be increased by using a pump 104 as seen in Figure 7.

In many older pipes there can be considerable debris on the floor of the pipe 12. This

debris can reduce the effectiveness of the linestopping operation and make it difficult for

the plug 50 to be inserted into the pipe 12. To alleviate this problem the following

method may be employed.

The high pressure fluid from the fluid supplying means 90 may be fed from the hose 94

into the hose 74 and then into jet hose 62 and through to the apertures 58 where it is

expelled to push debris out of the way. The insertion angle of the plug 50 causes the nose

plug 52 to push some of the debris out of the way, and the high pressure fluid from the

jet hose 62 assists in the removal of any debris left over. The plug 50 may be inserted

more than once to push and squirt clear a large enough section of pipe for an effective

linestopping operation. The plug 50 of the linestopping system 10 includes a thick outer covering of rubber. The plug 50 may be approximately 400mm in outer diameter when uninflated for use with a

pipe 12 of approximately 1000mm inner bore. The plug 50 for this type of pipe 12 would

be approximately 3.5m long when uninflated. The length of plug 50 and the deformable

rubber outer cover allow the plug 50, when uninflated in the pipe 12, to seal around

debris and irregularities of up to 100mm in size.

When the section of pipe to be replaced or repaired has been attended to, the linestopping

plug or plugs 50 may be deflated and withdrawn from the pipe. The deflated plugs 50

are withdrawn into the pipe by the insertion mechanism 34. The valve 28 is then closed

and the insertion mechanism 34 can be detached from the branch pipe support 20. The

branch pipe support 20 is left in position on the pipe 12 permanently.

The linestopping system 10 may be used with a large variety of pipe diameters and with

very high internal pressures, for example up to HOOkpa.

The length of the plug 50 allows for a larger surface area than other known linestopping

devices. The larger surface area of the plug 50 results in a lower pressure being required

to effectively stop the flow in the pipe 12. This is very important in frail and old pipes

as too high on internal pressure may rupture or further damage the pipe.

Modifications and variations such as would be apparent to the skilled addressee are

deemed to be within the scope of the present invention.

Claims (11)

1. A linestopping system for pipes characterised by first and second linestopping means, each linestopping means including an inflatable plug, an inflation means and an insertion means, first and second branch pipe supports each having an apertured flange with a pipe section mounted thereon at an acute angle, each pipe section containing a

valve wherein, in use, the pipe supports are disposed on a pipe in spaced apart locations

with the pipe sections facing in opposite directions such that upon apertures being cut in

the pipe at the pipe supports inflatable plugs of respective line stopping means may be

inserted by the insertion means through the apertures in the pipe and subsequently

inflated by the inflation means so as to seal off a section of the pipe.

2. A linestopping system according to claim 1, characterised in that the acute angle

of the pipe sections is from 30° to 50° to the centre line of the pipe.

3. A linestopping system according to claim 2, characterised in that the acute angle

of the pipe sections is from 35° to 45° to the centre line of the pipe.

4. A line stopping system according to any one of the preceding claims,

characterised in that there is provided a bypass pipe which is arranged to extend between the first and second linestopping means to allow fluid flow to be maintained when the

section of the pipe is sealed off.

5. A line stopping system according to claim 4, characterised in that the bypass pipe contains a pump for enhancing fluid flow along the bypass pipe.

6. A linestopping system according to any one of the preceding claims, characterised in that each inflatable plug is provided with at least one high pressure nozzle at a forward

point thereof for expelling one or more high pressure jets of fluid into the sealed off

section of pipe for clearing away debris at the bottom of the pipe.

7. A line stopping system according to claim 6, characterised in that a low pressure

fluid conduit extends from the inflation means to the inflatable plug, and a high pressure

fluid conduit extends from the inflation means to each high pressure nozzle.

8. A line stopping system according to claim 7, characterised in that the high pressure fluid conduit is contained within the low pressure fluid conduit over a major

portion of its length.

9. A linestopping system according to any one of the preceding claims, characterised in that each insertion means includes a plurality of sets of hydraulic clamps, a first set

of clamps being fixed relative to the insertion means and a second set of clamps being movable relative to the insertion means, such that the first and second sets are relatively

moveable so as to cause insertion of the respective inflatable plug into the pipe.

10. A linestopping system according to any one of the preceding claims, characterised

in that each inflatable plug includes a deformable outer skin covering a plurality of reinforcing wires.

11. A linestopping system according to claim 8, characterised in that the outer skin

is from 20mm to 60mm thick.