WO2010018357A1

WO2010018357A1 - Pipe lining

Info

Publication number: WO2010018357A1
Application number: PCT/GB2009/001883
Authority: WO
Inventors: Geoffrey Hopkins; John Holleran
Original assignee: Dvs Technology Limited
Priority date: 2008-08-11
Filing date: 2009-07-31
Publication date: 2010-02-18
Also published as: GB2462607A; GB0814663D0

Abstract

A lining material is applied to the interior surface of a gas or water pipe (28) by an applicator (12) drawn through the pipe (28). It is necessary to ensure that the applied lining has a minimum thickness so that it is semi-structural to resist ring fractures and other defects in the pipe wall. This is achieved, in one embodiment, by measuring the speed of the applicator (12) and the applicator to reduce errors in the speed signal from which the thickness is calculated. In other embodiments, a similar effect is achieved by drawing the applicator (12) through the pipe (28) by a tractor (42) within the pipe (28). Measuring apparatus (46) may measure the actual thickness of the lining.

Description

PIPE LINING

The invention relates to the lining of pipes.

5

It is known in pipes, particularly in relation to water and gas pipes, that after many years in the ground, leaks can develop. In the case of water pipes, this can result in a significant loss of this valuable resource. In the case of gas pipes, there can be potentially explosive consequences, as well as loss.

10

This can be overcome by removing the old pipe and replacing it with a new pipe. This is, however, slow, expensive and disruptive. It is also known to line such pipes by moving an applicator along the interior of the pipe and passing a lining material to the applicator from a base unit through a hose, so that the applicator applies a coating of the material to the

[ 5 interior surface of the pipe.

In these known arrangements for water pipes, the applicator is connected to the base unit by a hose that is winched-in at the base unit to move the applicator along the pipe. From a knowledge of the diameter of the pipe, the feed rate of the lining material and the speed of >0 the hose winch, a coating thickness can be derived. After the lining has been applied, a camera may be passed through the pipe to allow a visual examination of the lining. Such a visual inspection may reveal unevenness in the coating thickness in an axial direction ("ringing") but does not provide any absolute measurement of coating thickness. If this visual inspection shows regions of possibly unsatisfactory coating, then a further coating may be applied.

This is not a problem with water pipes because a leak from a faulty lining results only in the release of water and, while this may be expensive to repair, there are no highly dangerous consequences. This is not, however, the case with gas pipes. If the lining is not of the required thickness and gas leaks from the pipe, perhaps on a ring fracture of the pipe, there is the potential for explosions. For this reason, it has not been possible to use the lining techniques described above for water pipes, on gas pipes. For gas pipes, the coating must have at least a specified thickness.

According to a first aspect of the invention, there is provided a pipe lining apparatus comprising a base unit including a supply of lining material, a hose assembly connecting said supply to an applicator for movement along an interior of a pipe to apply said lining material to an interior surface of the pipe, the applicator including a speed sensor for generating a signal representing the speed of the applicator along the pipe.

According to a second aspect of the invention, there is provided a method of lining pipes comprising supplying to the pipe lining material at a known flow rate, applying the lining material to the interior surface of the pipe through an applicator, moving the applicator along the pipe, measuring the speed of movement of the applicator at the applicator and then deriving from said flow rate and said speed a thickness of the lining material on said inner surface. By generating the speed signal at the applicator, a much more accurate speed signal is obtained because it eliminates, for example, the effect of stretch in the hose connecting the base unit to the applicator. Thus, the measurement of lining thickness is more accurate and this allows such a lining technique to be applied to gas pipes as well as water pipes.

According to a third aspect of the invention, there is provided pipe lining apparatus comprising a base unit including a supply of lining material, a hose assembly connecting said supply to an applicator for movement along an interior of the pipe to apply said lining material to an interior surface of the pipe and means for insertion into the pipe for moving the applicator along the pipe at a constant known speed.

In this arrangement the motive power for the applicator is derived from means, such as a tractor unit, that is inserted into the pipe and used to draw the applicator along the pipe at a constant known speed. The calculation of the thickness of the lining along the pipe can thus be more accurate and, again, this allows such apparatus to be used for lining gas pipes as well as water pipes.

As discussed above, it is known to calculate the thickness of the lining from data such as the flow rate of the lining material, the diameter of the pipe and the speed of movement of the applicator. According to a fourth aspect of the invention, there is provided a method of lining a pipe with a lining material comprising moving a spray of lining material along on interior surface of a pipe from a first end of the pipe to a second end of the pipe, and then measuring the thickness of the lining at a succession of positions along the length of the pipe.

Producing a measured thickness, in contrast to a calculated thickness, allows the minimum thickness required for lining gas and water pipes to be assured.

According to a fifth aspect of the invention, there is provided a method of lining a pipe with a lining material comprising moving a spray of lining material along an interior surface of a pipe from a first end of the pipe to a second end, and adjusting the rate of application of the lining material to the pipe to vary the thickness of the lining along the pipe.

The following is a more detailed description of some embodiments of the invention, by way of example, reference being made to the accompanying drawings, in which:-

Figure 1 is a schematic view of a section of gas pipe laid in the ground and a pipe lining apparatus including a base unit above the ground, an applicator within the pipe and a hose inter-connecting the unit and the applicator ,

Figure 2 in a schematic view of a control unit of the base unit of Figure 1 together with two component tanks for lining material and showing the hose in cross-section, Figure 3 is a cross-section of the hose of Figure 2, in more detail.

Figure 4 is a schematic cross-sectional view of a gas pipe showing the applicator of Figures 1 to 3 drawn by a tractor, and

Figure 5 is a schematic cross-sectional view of a gas pipe showing the applicator of Figures 1 to 3 fitted with a device for measuring the thickness of a lining applied to an interior surface of the pipe.

Referring first to Figure 1, the pipe lining apparatus comprises a base unit 10, a hose 11 and an applicator 12. The base unit 10 includes a control unit 13, first and second tanks 14 and 15 and a winch 16. The base unit 10 further includes a source of compressed air 17 and a source of heated fluid 18.

The hose assembly 11 is formed of six bundled hoses which may be spirally wound together. The first and second hoses 19, 20 are for conveying lining components from the first and second tanks 14, 15 respectively to the applicator 12. A third hose 21 is for conveying compressed air from the source 17 to the applicator. A fourth hose 22, a fifth hose 23 and a sixth hose 24 are for conveying heated fluid to and from the source of heated fluid 18 towards the applicator 12 to condition the lining material during its passage from the base unit 10 to the applicator 12. The bundle also includes an electrical cable 39, as better seen in Figure 3. The hoses 19, 20, 21, 22, 23, 24 are arranged so that a heated fluid hose 22, 23, 24 alternates with one of the other hoses 19, 20, 21 to allow the uniform dispersal of heat from these hoses 22, 23, 24 to the component hoses 19, 20.

5 The applicator 12 comprises a rotatable spray head 25 carried by a body 26. The body includes skids 27 for guiding the applicator 12 through a pipe 28, described in more detail below. The spray head 25 is driven by air from the third hose 21. The applicator 12 also includes a speed sensor indicated generally at 29 and formed by a wheel 30 that contacts the interior surface of the pipe 28 and whose rotation is converted by a transducer 31 into an

10 electrical signal passed to the control unit 13by the electrical cable 39 in the bundle. There may also be a sensor for measuring the national speed of the head 25, if this is subject to variation.

The apparatus described above with reference to Figure 1 is for lining a gas or water pipe 28.

L 5 The pipe conveys gas from a source to a user and is buried beneath the ground 32. Older gas or water pipes 28 are commonly made of cast iron and, over the years, are subject to corrosion and possible fracture. One cure for this is to dig up the pipe 28 and replace it with a new pipe, but this is slow, time consuming and expensive. The alternative, now to be described, lines the pipe with a lining material which is semi-structural; that is to say, it

10 produces a lining that does not rely wholly on the pipe 28 to support it. In order to achieve this, it is essential that the lining of the pipe has a predetermined minimum thickness. This is achieved in the following way by the apparatus described above with reference to Figure 1. Referring to Figures 1 and 2, a first trench 33a is dug in the ground 32 and a first end 34 of the pipe 28 is exposed. A second trench 33b is also dug to expose a second end 35 of the pipe 28. The hose assembly 11 is fed into the pipe 28 from the first end 34 and moved to the second opposite end 35 of the pipe 28. The applicator 12 is inserted into the second end 35 of the pipe 28 and attached to the hose assembly 11.

The lining material is formed by a base component and an activator component that are placed in the first and second tanks 14, 15 respectively. The lining may be any suitable material such as the material sold under the trade name Copon Hycote™ 169HB or XS. These products have passed the LC8 standard set by National Gas Grid for product suitability. The two components are fed from the respective tanks 14, 15 and passed to the first and second hoses 19, 20 respectively as seen in Figure 2. The rates of flow of both components are monitored by flow meters 36, 37 and a signal representing the rates of flow of the components is fed to the control unit 13.

At the same time, compressed air is fed from the source 17 to the third hose 21 and then to the spray head 25 to rotate the spray head. In addition, a heated fluid, such as water, is fed from the source 18 through the fourth, fifth and sixth hoses 22, 23 and 24 to keep the lining material components conditioned during their passage along the first and second hoses 19, 20. The pipe 28 to be lined may be prepared by an internal cleaning process that removes scale and other loosely attached material from the interior surface of the pipe 28 to ensure a relatively smooth surface and a good key between the lining material and the pipe 28. Air from the third hose 20 rotates the spray head 25 and the conditioned lining material components and mixed and then sprayed from the spray head 25 onto the interior surface of the pipe 28. At the same time, the hose assembly 11 is winched in by the winch 16. Accordingly, as the applicator 12 moves along the pipe 28, the interior surface of the pipe 28 is sprayed with the lining material.

As mentioned above, it is imperative that the thickness of the coating is at least a minimum predetermined thickness. This may, for example, be 3mm for certain lining materials. Once the diameter of the pipe is known, the flow rate of the lining material is known and the speed of the applicator 12 is known, it is possible to calculate the thickness of the lining being applied. Accordingly, for a given pipe diameter, the flow rate of the speed are adjusted to give a lining of a required thickness of, for example, 3mm.

The control system 13 is fed with the diameter of the pipe and receives signals corresponding to the flow rate of the lining material and the speed of the applicator 12 (and the national speed of the head 25, if provided). From this, the control system 13 calculates the thickness of the lining and this is provided on a printout. (The printout may also include a printout of the speed and the flow rate of the lining material). Since the speed sensor 29 is provided on the applicator 12, the speed signal will be an accurate speed signal and inaccuracies arising from stretch and contraction of the hose assembly 11 are avoided. The printout from the control unit ¹I 3 thus contains an accurate calculation of the lining thickness so allowing the apparatus to be used for lining gas pipes as well as water pipes.

The lining cures usually within a period of approximately 1 to 2 minutes of being applied to the interior surface of the pipe 28. After the lining has been applied, the applicator 12 may be withdrawn and a CCTV camera inserted into the pipe 28 and drawn along the pipe from the second end 35 to the first end 34 to transmit back to the control unit 13 (or, if required, a separate control unit) an image of the interior of the pipe. This image can be viewed to determine the presence of faults such as ringing in the lining. One suitable system uses a fish-eye camera and is sold under the trade mark DigiSewer.

If this visual inspection of the image shows ringing, for example, the lining process can be repeated as described above.

The system described above with reference to Figures 1 and 2 measures the speed of the applicator 12 from a speed sensor 29 provided at the applicator 12. As mentioned above, this eliminates any inaccuracies due, for example, to extension and contraction of the hose assembly 11 that might affect the measurement if the speed were taken at the base unit 10 by measuring the speed of movement of the hose assembly 11. The calculated thickness is thus very accurate and a read-out of such calculated thicknesses can allow the thickness of the lining to be adjusted as the pipe is being lined to increase or decrease thickness as required. This can be done by varying the speed of movement of the applicator 12. In addition, it would allow pre-determined adjustments of lining thickness at pre-determined positions along the pipe 28. For example, it may be required to apply a greater thickness of lining material at j oints .

Referring next to Figure 4, there is shown a further modification of the apparatus of Figures 1 and 2. In Figure 5, parts common to Figures 1 and 2 on the one-hand, and to Figure 5, on the other-hand, are given the same reference numerals and will not be described in detail.

In this embodiment, the applicator 12 is mounted on and drawn through the pipe 28 by a tractor unit 42. As seen in Figure 4, the tractor unit includes a motor 43, a drive 44 and wheels 45, at least one of which is powered. The motor may be an electrical motor fed by a current in a cable passing through the cable 39 or it may be a pneumatic motor powered by air from the third hose. Alternatively, it may be hydraulically powered with hydraulic fluid being passed to the motor 43 through a pipe in the fourth, 22 fifth 23 or sixth hose 24.

The tractor unit 42 has significant weight, a motor 43 and wheels 45, accurately controllable by control means 46, that apply the motor power to the interior surface of the pipe 28 without slipping. As a result, the tractor unit 42 pulls the applicator 12 at a completely uniform speed along the pipe 28 thereby resulting in the application of smooth lining free from the effects of ringing. Alternatively, the applicator 12 could be mounted on the tractor 42. Sensors 47 (see Figure 1) record the tension in the hose assembly 11 to ensure that it is withdrawn at a controlled rate by the winch 16 in order that the tractor unit 42 neither catches up with and drives over the hose assembly 11 nor is intentionally pulled by the hose assembly 11.

In the embodiments described above with reference to the drawings, the thickness of the lining on the interior pipe 28 is calculated by the control unit 13 from the diameter of the pipe, the flow rate of the lining material and the speed of the applicator 12. Various proposals described above with reference to the drawings are designed to make the speed of the applicator 12 as constant and accurate as possible so giving corresponding accuracy to the calculated lining thickness.

It is possible, however, to measure the thickness of the lining after the lining material has been applied. Referring now to Figure 5, in which parts common to Figure 5, on the one- hand, and to Figures 1 to 4, on the other-hand, are given the same reference numerals and will not be described in detail. A rig 49 is provided with a sensor 46. There may be one sensor 46 or a number of sensors 46 arranged at angularly spaced intervals around the rig 49. The sensor or sensors 46 could use magnetic field, eddy currents or ultrasound to measure the thickness of the lining along the length of the pipe 28 and at one or more angularly spaced positions around the pipe 28. The rig 19 is inserted into the pipe 28 after lining is completed and sufficiently cured and drawn along the pipe 28. The signals from the sensor or sensors 46 during such movement are fed through the cable 39 to the control unit 13 or to a separate control unit. The control unit 13 can thus produce an output giving an actual thickness measurement for the lining. This is clearly important for gas or water pipes 28 where it is essential that the lining is sufficiently thick to have structural integrity in the case of, for example, a ring fracture for the gas or water pipe 28.

Of course, the signals from the sensor or sensors 46 could be processed other than as described above. For example, a wireless connection could be used.

It may be possible with some sensors 46 to measure also the thickness or deterioration destination of the pipe 28. This is useful in identifying thin or corroded sections of the pipe 28.

The rig 49 could be omitted and the transducer or transducers 46 mounted on the applicator 12. In this case, the applicator 12 will be drawn through the pipe 28 a second time to measure thickness. The applicator 12 may be a skid frame or a slow motion/inertia type trolley

The control unit 13 may be programmed to output a printed record that includes the calculated lining thickness, the speed of the applicator 12, and the pressures of the components of the lining material at spaced axial positions (i.e. spaced times of travel of the applicator 12) along the pipe 28. It also includes printouts of the thickness of the lining as measured by the transducer or transducers 46 and an unfolded image from the fish-eye camera. Where the thickness of the pipe 28 is measured, this may also be included. Thus, all the data required to confirm the compliance of the lining to a required thickness is produced on a single data carrier.

Claims

1. A pipe lining apparatus comprising a base unit (10) including a supply (14, 15) of lining material, a hose (11) connecting said supply to an applicator (12) for movement along an interior of a pipe (28) to apply said lining material to an interior surface of the pipe (28), the applicator (12) including a speed sensor (29) for generating a signal representing the speed of the applicator (12) along the pipe.

2. Apparatus according to claim 1 wherein the hose (11) is associated with an electrical cable (39) for feeding said signal from the applicator (12) to the base unit (10).

3. Apparatus according to claim 1 or claim 2 wherein the speed sensor comprises a wheel (30) that engages said interior surface of the pipe (28), rotation of said wheel (30) being converted by an encoder (31) into said signal.

4. Apparatus according to any one of claims 1 to 3 wherein the base unit (10) includes a control system (13) for measuring the flow rate of the lining material along said hose (11), the base unit (10) receiving said signal and deriving from said signal and said flow rate a thickness of the applied lining material.

5. Apparatus according to any one of claims 1 to 4 wherein the applicator (12) includes a head (25) rotatable about an axis generally parallel to the pipe axis for applying the lining material to the inner surface of the pipe (28), the head (25) being associated with a sensor for generating a signal representing the rotational speed of the head (25).

6. Apparatus according to claim 5 when dependant on claim 2, wherein said signal is fed along the electrical cable (39) to the base unit.

7. A method of lining pipes comprising supplying to the pipe (28) lining material at a known flow rate, applying the lining material to the interior surface of the pipe (28) through an applicator (12), moving the applicator (12) along the pipe, measuring the speed of movement of the applicator (12) at the applicator (12) and then deriving from said flow rate and said speed a thickness of the lining material on said inner surface.

8. A pipe lining apparatus comprising a base unit (10) including a supply of lining material, a hose (11) connecting said supply to an applicator (12) for movement along an interior of the pipe (28) to apply said lining material to an interior surface of the pipe (28) and means (42) for insertion into the pipe for moving the applicator (12) along the pipe at a constant known speed.

9. Apparatus according to claim 8 wherein the means comprise a drive unit (42), the drive unit, in use, traveling through the pipe (28) to move the applicator (12) along the pipe

(28), the drive unit (42) including control means for controlling the travel of the drive unit (42) to a constant speed.

10. Apparatus according to claim 9 wherein the applicator (12) includes a body (26) guided for movement along a pipe (28), the drive unit (42) being separate from the applicator and being connected to the body (26) to move the applicator (12) along a pipe (28).

11. Apparatus according to claim 12 or claim 13 wherein the drive unit includes a sensor provides an output signal representing the tension in the hose (11), said signal being fed to the base unit (10).

12. Apparatus according to claim 11 wherein the hose (11) is withdrawn from the pipe (28) as the applicator (12) is moved along the pipe (28) said signal being used to control the speed of withdrawal of the hose (11) in accordance with the tension in the hose (11) so that the drive unit (42) neither catches up with the hose (11) nor is pulled by the hose (11).

13. A method of lining a pipe with a lining material comprising moving a spray of lining material along an interior surface of a pipe (28) from a first end of the pipe (28) to a second end of the pipe (28), and then measuring the thickness of the lining at a succession of positions along the length of the pipe (28).

14. A method according to claim 13 wherein the measuring step includes measuring in addition the thickness of the lining at two or more angularly spaced locations around the interior of the pipe and each position.

15. A method according to claim 13 or claim 14 and further comprising photographing the interior of the lined pipe and producing an image of the interior and laying the recording of the lining out as a flat image for inclusion on a combined spray lining record sheet.

16. A method according to claims 13 to 15 and including outputting said measurement on a data carrier together with said camera image.

17. A method of lining a pipe with a lining material comprising moving a spray of lining material along an interior surface of a pipe (28) from a first end of the pipe (28) to a second end of the pipe (28), and adjusting the rate of application of the lining material to the pipe (28) to vary the thickness of the lining along the pipe (28).

18. A method according to claim 17 wherein the adjustment of the rate of application is in accordance with a pre-determined required variation in thickness of the lining along the pipe (28).

19. A method according to claim 17 and comprising determining the thickness of the lining along the pipe (28) and adjusting the rate of application of the lining material in accordance with said determined thickness.

20. A method according to claim 19 wherein the determined thickness is a measured thickness.

21. A method according to claim 19 wherein the determined thickness is a calculated thickness.

22. A method according to any one of claims 17 to 21 wherein the thickness of the lining is varied by varying the speed of movement of the spray along the pipe (28).