WO2008032026A1

WO2008032026A1 - Methods of lining a conduit and devices for same

Info

Publication number: WO2008032026A1
Application number: PCT/GB2007/003391
Authority: WO
Inventors: Wayne Hughes
Original assignee: Knex Pipelines & Cables Ltd
Priority date: 2006-09-11
Filing date: 2007-09-11
Publication date: 2008-03-20
Also published as: GB0617823D0; GB0906174D0; GB2455265A

Abstract

There is provided a method of lining a conduit (10) including the steps of : introducing a plastic lining (12) into the conduit (10); sealing the lining (12) against an inner wall of the conduit (10) by the application of heat and, optionally, pressure, in which heat and, optionally, pressure is applied by a heating device (14) which is translated along the lining (12).

Description

. Methods of Lining a Conduit and Devices for Same This invention relates to methods for lining a conduit and heating devices for use in lining conduits, with particular, but by no means exclusive, reference to the lining of pipes. There is much interest in the provision of a practical method for the in situ lining of water pipes. However, to date a satisfactory, practical method is lacking. Amongst the extensive prior art, DE 3904524 discloses the lining of conduits using a non cross-linked plastic which is expanded at a temperature below the softening temperature of the plastic. DE 2912840 and DE 3033528 disclose methods for lining conduits in which an adhesive is used to attach a lining to the conduit. EP 0122246 describes a procedure in which an elastic hose formed from a cross-linked plastic is inflated using compressed air and pushed against the wall of the conduit. Heat treatment causes hardening of the cross-linked plastic. It is also known to utilise so called shape memory materials to line pipes as disclosed, for example, in EP 1271042, EP 0360319, JP 2002-

018956, and JP 2000-313065.

The present invention is directed primarily towards methods of lining water pipes, although the method can be applied more generally to other types of pipe and indeed to other conduits. The present invention seeks to provide a convenient and practical means for lining conduits in situ.

According to a broad first aspect of the invention there is provided a method for lining a conduit including the steps of: introducing a plastic lining into the conduit; sealing the lining against an inner wall of the conduit by the application of heat and, optionally, pressure, in which heat and, optionally, pressure is applied by a heating device which is translated along the lining.

Any convenient method of sealing the lining against the inner wall of the conduit might be employed. For example, the lining may be directly sealed against the inner wall of the conduit, or a heat activated adhesive may be used.

In preferred embodiments, a lining of a non cross-linked plastic is used, and the lining is expanded at a temperature below the softening temperature of the plastic. Alternatively, the lining may be formed from a shape memory material.

The conduit may be a pipe, which in preferred applications is a water conducting pipe.

Preferably, the heating device is an infra-red (IR) heater. Heating devices of this type can be conveniently produced and utilised, and the lining process can be conveniently controlled and altered.

In preferred embodiments, the heating device includes one or more sensors for measuring a parameter relevant to the sealing of the liner and, during the step of sealing the liner, the output of the sensors is communicated to control means which control the operation of the heating device in response to the output of the sensors. In this way, the lining process can be optimised, and can be adjusted in response to the actual conditions encountered during use. Advantageously, the heating device includes one or more temperature sensors.

Other sensors, such as pressure and movement transducers, might be utilised.

In further preferred embodiments, the heating device further includes cooling means for cooling portions of the lining which have been heated by the heating means. According to a second aspect of the invention there is provided a heating device for sealing a lining against an inner wall of a conduit, the device including heating means and being translatable through the conduit to seal the lining against the inner wall of the conduit. Preferably, the heating means includes an IR heater. Advantageously, the heating device includes a plurality of IR heating elements disposed circumferentially about the device so as to provide even heating of a cylindrical lining.

Advantageously, the heating device further includes one or more sensors for measuring a parameter relevant to the sealing of the lining.

Preferably the heating device includes one or more temperature sensors. The heating device may include a first temperature sensor disposed at a leading portion of the device so as to measure the temperature of the lining before heating takes place, and a second temperature sensor disposed further towards the rear of the device so as to measure the temperature of the lining during or shortly after heating. In this way, an accurate indication of the amount of heating required can be provided on an on-going basis during the lining process. The term "leading" refers to the front portion of the device as it is translated through the conduit, i.e., the portion of the device that first makes contact with a given region of the lining.

Alternatively, or additionally, the heating device may include one or more pressure sensors and/or one or more movement/position sensors.

Preferably, the heating device further includes cooling means for cooling the lining after the lining is sealed to the conduit. Advantageously, the cooling means includes means for dispensing a cooling fluid, preferably a cooling gas.

The heating device may further include a plurality of guide members, preferably rollers, disposed around the periphery of the device for contacting the liner. The heating device may further include a cradle on which the heating means (such as the one or more IR heating elements) are disposed.

The heating device may further include a cable enabling the device to be translated through the conduit. Typically, the cable is situated at the leading portion of the device, and is pulled through the conduit. The cable may perform ancillary functions, such as carrying electrical wiring enabling, for example, the heating means to be powered, the sensors to be powered and/or the outputs of the sensors to be monitored. Additionally, cooling fluid may be conducted to the cooling means through the cable. Alternatively, a separate cable or cables (for example a cable in connection with the rear of the device) might be utilised for these purposes.

The heating device may have a camera disposed thereon.

According to a third aspect of the invention there is provided a system for lining a conduit with a lining including: a heating device according to the second aspect of the invention; and means for translating the heating device through the conduit.

Preferably, the system further includes control means for automatically controlling the operation of the heating device.

Whilst the invention has been described above, it extends to any inventive combination or sub-combination of the features set out above or in the following description or drawings or claims.

Embodiments of heating devices, systems and methods in accordance with the invention will now be described with reference to the accompanying ^'drawings, in which: Figure 1 is a partially cut-away side view of a heating device of the invention positioned within a lining in a pipe; and

Figure 2 depicts a system of the invention for lining a pipe. Figure 1 shows a pipe 10 which is depicted in partially cut-away form to reveal a lining 12 which has been inserted into the pipe 10 by any convenient means. In turn, the pipe 12 is shown in partially cut-away fashion to reveal a heating device, generally shown at 14, which is being translated therethrough. The heating device 14 comprises an infra-red emitter 16 which is disposed on a cradle structure 18. The cradle structure 18 supports a plurality of guide rollers 20 disposed circumferentially around a leading portion of the device and a plurality of guide rollers 22 disposed circumferentially around the rear of the device. The guide rollers 20,22 ensure smooth running of the device 14 against the lining 12 and through the pipe 10. The guide rollers 20,22 also enable pressure to be applied against the lining 12, which may be required as part of the sealing process. Disposed at the rear of the device 14 are one or more outlets 24 from which one or more jets of compressed air can be emitted for cooling purposes. Other cooling fluids might be envisaged, such as carbon dioxide. The provision of a cooling function to cool portions of the lining 12 soon after heating is advantageous since it permits the pipe 10 to be restored to operational use more quickly. Additionally, it is envisaged that the cooling facility may, in some instances, assist in the sealing process.

The heating device 14 further comprises a cable 26 attached to the leading portion of the device thereby enabling the device to be pulled through the pipe 10. Wires enabling electrical contact to be made with the IR emitter 16 and a conduit for conducting compressed air to the outlet 24 may be disposed in the cable 26.

The IR emitter 16 is utilised as a convenient source of heat for effecting the sealing of the lining 12 to the inner wall of the pipe 10. It is convenient to provide a plurality of IR emitters which can be mounted in the cradle 18 to radiate IR energy relatively evenly over the entire circumference of the device 14. The IR energy is subsequently absorbed by the lining 12 causing it to heat up to the temperature required for the sealing process. Preferably, the IR emitters employ a low mass tungsten or carbon filament which allows rapid responses to changes in thermal characteristics during operation. Known IR heaters may be incorporated into devices of the invention; such heaters are manufactured by a number of producers, such as Heraeus Noblelight GmbH of Hanau, Germany. The heating device can be utilised in conjunction with a number of pipe sealing methodologies. In a preferred procedure, the lining 12 is formed from a non cross-linked plastic which is heated by the heating device to a temperature below its softening temperature and expanded into contact with the inner wall of the pipe 10. Further details of the general procedure can be found in DE 3904524, the contents of which are herein incorporated by reference. It has been found to be particularly convenient to employ a lining formed from a polyolefin or modified polyolefin , especially polypropylene. In an alternative procedure, a heat activated adhesive is provided on the outside of the lining, and the heating device is used to activate the adhesive thereby sealing the lining to the pipe. In preferred embodiments, the lining is formed from a polyolefin or modified polyolefin, with polypropylene being particular preferred. In further alternative procedures, the lining is formed from a cross- linked plastic or a shape memory material. The reader is referred to DE 3033528, EP 0122246, EP 1271042, EP 0360319, JP 2002-018956 and JP 2000-313065, the contents of all of which are herein incorporated by reference, for further general information relating to these procedures.

The heating device 14 is provided with a plurality of sensors (not shown) which provide information which is monitored in order to control the operation of the device. It is particularly advantageous to provide one or more temperature sensors so that the sealing process can be monitored and controlled. In a preferred arrangement, a temperature sensor is disposed on the heating device so that the temperature close to the heat source 16 and/or the portion of the lining being heated by the heat source 16 is measured and another temperature sensor is disposed on the device so that the ambient temperature of the pipe 10 is measured. In this way, the amount of energy required in order to obtain a desired process temperature can be determined. Pressure movement transducers might also be incorporated in the heating device, as may one or more cameras in order to facilitate visual analysis of the lining and the sealing process.

Figure 2 shows a system, depicted generally at 30, for lining a pipe 32 with a lining 34 using a heating device 36 of the invention. The heating device 36 includes a cable 37 which enables the heating device 36 to be pulled through the lining 34 and conduit 32 by a suitable winding device 40. The system further comprises a computer 42 which acts as a control system to control the operation of the heating device 36. More specifically, the computer 42 controls the operation of the winding device 40, and hence the movement of the heating device 36, via a lead 44, and controls the heating source of the heating device 36 via a lead 46. The computer 42 is adapted to control the lining of conduit according to a predefined operating regime. However, the computer also receives and monitors the output of the sensors via lead 48 so that all actions

(e.g. heating, dwell time, forward and radial movements of the heating device) are automatically computer controlled to account for variations in the conditions encountered in the pipe 32. Feedback control methods may be utilised in order to vary the operating conditions in response to the output of the sensors. Adaptive control methodologies might be employed. The computer 42 ensures that the heating device is moved through the liner 34 at an appropriate rate. The rate of movement is controlled by a physical state of the liner, i.e., forward and radial movements are only made when the liner is in an appropriate state to be pushed outward to contact the pipe 32. It is possible to simulate the lining process, for example by constructing a heat and mass balance model of the process (in fact, the simulations might be used to guide the design of the heating device). The process control parameters could then be defined and refined using these simulations.

Although it is possible to draw the heating device 36 through the liner 34 continuously at an appropriate rate, it is envisaged that it would be more desirable to separate the radial movement of the liner 34 from the axial movement of the heating device 36 to prevent the dragging of the liner material forward through frictional drag once it has been rendered soft by heating. In other words, it is preferred to translate the heating device 36 through the liner 34 in a stepwise fashion in which movement of the heating device takes place prior to heat being applied and radial expansion of the lining 34 occurring.

Numerous variations to the embodiments discussed above are possible. For example, telemetry might be used in place of wires to communicate with the heating device. Although the use of an IR heater is preferred, other heat sources, such as UV or hot fluid heat sources, might be contemplated. A hot fluid heat source might utilise inert gases (for example nitrogen), steam (which may be super heated) or oil. The exterior surface of the heating device which contacts the lining 12 might be designed in accordance with the desired pressure that the liner should be subjected to during the sealing process employed. For example, the exterior of the device may be a continuous shell structure, such as a cone shape. Such a shape is particularly desirable in embodiments in which the heating device is drawn continuously through the liner. In further variations, at least a portion of the exterior of the heating device contacts the lining and is of variable size, ie, this portion of the exterior can be expanded and contracted as desired in order to vary the pressure applied to the lining. The pressure applied to the lining can be monitored by appropriate sensors and the information provided can be used by the control means to control the expansion and contraction of the exterior so as to ensure that a desired contact pressure is applied.

Claims

1. A method of lining a conduit including the steps of: introducing a plastic lining into the conduit; sealing the lining against an inner wall of the conduit by the application of heat and, optionally, pressure, in which heat and, optionally, pressure is applied by a heating device which is translated along the lining.

2. A method according to Claim 1 in which the conduit is a pipe.

3. A method according to Claim 1 or Claim 2 in which the heating device is an infra-red (IR) heater.

4. A method according to any one of Claims 1 to 3 in which the heating device includes one or more sensors for measuring a parameter relevant to sealing of the lining and, during the step of sealing the lining, the output of the sensors is communicated to control means which controls the operation of the heating device in response to the output of the sensors.

5. A method according to Claim 4 in which the heating device includes one or more temperature sensors.

6. A method according to any previous claim in which the heating device further includes cooling means for cooling the lining after the step of the sealing the lining.

7. A heating device for sealing a lining against an inner wall of a conduit, the device including heating means and being translatable through the conduit to seal the lining against the inner wall of the conduit.

8. A heating device according to Claim 7 in which the heating means includes an IR heater.

9. A heating device according to Claim 7 or Claim 8 in which the heating device further includes one or more sensors for measuring a parameter relevant to the sealing of the lining.

10. A heating device according to Claim 9 which includes one or more temperature sensors.

11. A heating device according to Claim 10 in which a first temperature sensor is disposed at a leading portion of the device so as to measure the temperature of the lining before heating takes place, and a second temperature sensor is disposed further towards the rear of the device so as to measure the temperature of the lining during or shortly after heating.

12. A heating device according to any one of Claims 9 to 11 which includes one or more pressure sensors.

13. A heating device according to any one of Claims 7 to 12 further including cooling means for cooling portions of the lining which have been heated by the heating means.

14. A heating device according to Claim 13 in which the cooling means includes means for dispensing a cooling fluid, preferably a cooling gas.

15. A heating device according to any one of Claims 7 to 14 further including a plurality of guide members, preferably rollers, disposed around the periphery of the device for contacting the liner.

16. A heating device according to any one of Claims 7 to 15 further including a cradle on which the heating means is disposed.

17. A heating device according to any one of Claims 7 to 16 further including a cable enabling the device to be translated through the conduit.

18. A heating device according to any one of Claims 7 to 17 further including a camera.

19. A system for lining a conduit with a lining including: a heating device according to any one of Claims 7 to 18; and means for translating the heating device through the conduit.

20. A system according to Claim 18 further including control means for automatically controlling the operation of the heating device.