GB2554640A

GB2554640A - Sealing method

Info

Publication number: GB2554640A
Application number: GB1616490.7A
Authority: GB
Inventors: John Ryan Nicholas; Reid Jonathan; Mcintosh Angus
Original assignee: Scotland Gas Networks PLC; Southern Gas Networks PLC; Scotia Gas Networks Ltd
Current assignee: Scotland Gas Networks PLC; Southern Gas Networks PLC; Scotia Gas Networks Ltd
Priority date: 2016-09-28
Filing date: 2016-09-28
Publication date: 2018-04-11
Anticipated expiration: 2036-09-28
Also published as: GB201616490D0; EP3519522A1; GB2554640B; WO2018060713A1; US20190211958A1

Abstract

A method of sealing a leak in a pipe or duct, such as a gas pipe, by introducing a liquid aerosol into the pipe which may form a deposit on the inner surface of the pipe surrounding the site of the leak. The liquid aerosol comprises highly viscous droplets of a solution containing an organic solute. The solute may comprise a glass forming compound. Examples of the organic solute include saccharides, cellulose and polyols. The solute may be a sugar and may be trehalose, raffinose or sucrose. Also shown is a sealant system comprising an aerosol device, such as an atomizer, connected to a pipe wherein the aerosol device is adapted to aerosolize a liquid and introduce the aerosol into the pipe. A gas pipe comprising a seal covering a leak wherein the seal is on the inner surface of the pipe and comprises a glass forming compound is also shown as well as a gas pipe comprising a seal covering a leak wherein the seal is on the inner surface of the pipe and comprises one of a saccharide and a polyol.

Description

(54) Title of the Invention: Sealing method

Abstract Title: A method of sealing a leak in a pipe using a liquid aerosol (57) A method of sealing a leak in a pipe or duct, such as a gas pipe, by introducing a liquid aerosol into the pipe which may form a deposit on the inner surface of the pipe surrounding the site of the leak. The liquid aerosol comprises highly viscous droplets of a solution containing an organic solute. The solute may comprise a glass forming compound. Examples of the organic solute include saccharides, cellulose and polyols. The solute may be a sugar and may be trehalose, raffinose or sucrose. Also shown is a sealant system comprising an aerosol device, such as an atomizer, connected to a pipe wherein the aerosol device is adapted to aerosolize a liquid and introduce the aerosol into the pipe. A gas pipe comprising a seal covering a leak wherein the seal is on the inner surface of the pipe and comprises a glass forming compound is also shown as well as a gas pipe comprising a seal covering a leak wherein the seal is on the inner surface of the pipe and comprises one of a saccharide and a polyol.

— ₃₀ —

SO fig. 1

Reduce the pressure in the section of the network containing the leak from its normal operating pressure to a reduced pressure

Maintain the reduced pressure in the section of the network containing the leak '\ Provide an aerosol containing an organic compound

Introduce the aerosol into the section of the net wen k

Adjust the humidity of the section of the network ί Form a deposit containing the organic i ΐ compound on an inner surface of the pipe at the I | site of the leak increase the pressure in the section of the network containing the leak from the reduced pressure to its normal operating pressure

This print incorporates corrections made under Section 117(1) of the Patents Act 1977.

1/6

Reduce the pressure ip the section of the network containing the leak from its normal operating pressure to a reduced pressure

Maintain the reduced pressure in the section of the network containing the leak

Provide an aerosol containing an organic compound introduce the aerosol into the section of the network

Adjust the humidity of the section of the network

Form a deposit containing the organic

compound on an inner surface of the pipe at the site of the leak increase the pressure in the section of the ^Λ network containing the leak from the reduced pressure to its normal operating pressure

Fig. 1

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Fig. 2

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Fig. 4

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SEALING METHOD

FIELD OF THE INVENTION

The present invention relates to a method of sealing a leak in a pipe, a sealant system to be used in conjunction with the method and a pipe comprising a seal resulting from the method. In particular, the invention concerns the provision of a glass seal to seal a leak in a pipe.

BACKGROUND

Gas is transported through a network of pipelines from natural gas terminals to power stations and gas distribution companies which deliver the gas to industrial and domestic consumers. The network is a series of pipes connected by joints, which are traditionally steel, cast iron or plastic, the foundations of which can be decades old. The network forms a pressure envelope of pipes and other vessels, in which the pressure inside the envelope is determined by the operating pressure. The distribution network operates at two pressure ranges, low and medium. The low pressure network is rated to 75 mbar, but is generally operated at 15-30 mbar. The medium pressure distribution network is rated up to 2 bar. Both networks are defined in terms of differential pressures with respect to atmospheric pressures.

Continual exposure over time can cause the joints to weaken until they cease to be effective, leaving holes in the network. The pressure differentials from these holes result in gas leaks. The gases that seep out through these cracks and broken seals generally account for significant carbon release and hence contribute to the greenhouse effect. It therefore continues to be an objective in the gas industry to address gas leaks as quickly and efficiently as possible.

Gas leaks are usually addressed through an invasive procedure involving excavating, drilling into and injecting sealants into the faulty joints. It can be a lengthy and expensive process to excavate the underground pipes, particularly when the pipes are under roads and buildings in densely populated areas. Many safety measures need to be implemented before the work can begin, and a lot of harmful gases may have been released in the time taken to plan and reach the pipes.

Less invasive techniques have been developed and can involve robotic pipe crawlers to access the inside of the pipe. However, such techniques still require drilling into the joints and their reliance on wicking the sealant into existing joint material means they cannot accurately control the injection of the sealant.

Document WO 2015/149023 relates to a non-invasive and remote way of sealing leaks in pipelines. The document discloses a method of forming sealant particles which have an outer surface with a tack range that diminishes over time. The sealant particles flow through the leaky pipes and adhere to surfaces adjacent to a leak and to other particles to form a seal. However, such a method is difficult to use over long distances. This is because there is only a limited time for which the sealant particles have a tack range sufficient to form the seal. Moreover, it is not guaranteed that the sealant particles form a sufficiently impermeable seal.

In light of the current technology, there continues to be a need to provide a sealant which can be controlled and operated over long distances to address gas leaks with an immediate, impermeable and permanent effect. It is therefore an object of the present invention to overcome at least one of the problems in the prior art.

SUMMARY

According to a first aspect of the present invention, there is provided a method of sealing a leak in a pipe as defined in claim 1.

Ultra-viscous droplets in this specification means droplets that have a viscosity of 10³10⁷ Pa-s. The ultra-viscous droplets are formed as a solvent evaporates from a solution that contains an organic compound solute. The ultra-viscous droplets combine with one another to form a deposit that hardens into a seal on further drying. The resulting seal is a solid that is inert and non-porous with low permeability to gases and liquids. The seal therefore prevents fluids from seeping through leaks, particularly in pipes such as gas pipes, and remains strong for a significant amount of time. Furthermore, the droplets of the liquid aerosol can form a seal after being carried across large distances through the pipe. This means that the liquid aerosol does not need to be locally applied, but rather can be introduced into the pipe remotely. The present invention consequently removes the need to determine the precise location of a leak, which is particularly advantageous in sections of the network that are not easily accessible.

According to a second aspect of the present invention, there is provided a sealant system for sealing a leak in a pipe as defined in claim 25.

According to a third aspect of the present invention, there is provided a gas pipe comprising a seal covering a gas leak as defined in claim 33.

Embodiments of the present invention will now be described by way of further example only and with reference to the accompanying drawings, in which:

Fig. 1 is a flow diagram of a method for providing a glass seal to seal a gas leak in a pipe according to a preferred embodiment of the invention;

Fig. 2 is a schematic cross sectional view of a pipe in accordance with step 40 of the flow diagram of Fig. 1;

Fig. 3 is a schematic cross sectional view of a pipe in accordance with step 60 of the flow diagram of Fig. 1;

Fig. 4 is a cross sectional view of a pipe having a sealed leak in accordance with the present invention;

Fig. 5 is a schematic view of a sealant system for providing a glass seal to seal a gas leak in a pipe according to a preferred embodiment of the invention; and

Fig. 6 is a schematic cross-sectional view of an aerosol device installed onto a pipe.

DETAILED DESCRIPTION

The present invention relates to a method of sealing a leak in a pipe, a sealant system to be used in conjunction with the method, and a gas pipe comprising a seal covering a gas leak that results from the method.

The method of sealing the leak comprises introducing an aerosol of ultra-viscous droplets containing an organic compound into a section of a network containing the pipe having the leak. The droplets flow through the section of the network until they reach the site of the leak. As a result of the pressure differential between the pipe and its exterior, at least some of the droplets of the ultra-viscous liquid aerosol are diverted towards the leak. There is an accelerated flow through the leak that causes a turbulent flow at the site of the leak. The diverted droplets that experience the turbulence at the site of the leak collide with one another and the force of collision can cause them to combine with one other and to the surfaces of the pipe surrounding the leak. The droplets form a deposit, which grows in size as more droplets collide with it until it covers the leak. The deposit then hardens into a seal on further drying.

The present invention will now be described with reference to the figures.

A gas network comprises a pipe 100 having a gas leak 110 as shown in figures 2-5. The pipe 100 is a hollow cylinder, although the pipe 100 may take on the form of a different elongated hollow shape such as a rectangular pipe. The gas pipe 100 has a normal operating differential pressure of up to 75 mbar. The method however may also apply to pipes having normal operating differential pressures of up to 2 bar. A gas flow is transported through the section 120 of the network containing the leak 110 in a laminar flow pattern.

A first preferred embodiment relating to the method for sealing the leak 110 is shown in the flow diagram of figure 1. Steps 30, 40 and 60 relate to the process of sealing the leak 110, while steps 10, 20 and 50 relate to setting up the preferable pressure and humidity conditions for carrying out steps 30, 40 and 60. Step 70 relates to returning the pressure and humidity conditions within the section 120 of the network containing the leak 110 back to the normal operating conditions.

Step 10 of the method comprises reducing the pressure in the network section 120 that includes the pipe 100 containing the leak 110. This is an optional step directed to pipes which normally operate with differential pressures greater than 30 mbar. Step 10 of the method comprises reducing this normal operating pressure to a reduced pressure, in which the reduced pressure is a differential pressure less than 30 mbar. In other embodiments, the reduced pressure is a differential pressure less than 15 mbar.

The section 120 of the network containing the leak 110 over which pressure is reduced spans at least a length of 50 m of the network, and preferably a substantial length of around 500-1000 m, with the leak 110 located at an approximate midway point of this length. This is to ensure that both the pressure and humidity conditions within the section 120 of the network are stable and homogeneous. Additionally, as the present invention is carried out on such a substantial section of the network, the need to spend time and resources on determining the precise location of the leak 110 is removed. The precise location of the leak 110 is usually unknown, so this is particularly advantageous for sections of the network which are not easily accessible.

Step 10 is carried out using a preferred connection method of the network operator by bifurcating the path of the laminar gas flow throughout the section 120 of the network containing the leak 110. Since step 10 is carried out on a substantial section 120 of the network, existing infrastructure such as isolation points or network valves can be used as connection points that are in fluid communication with the pipes of the network section 120. The connection points (not shown) are connected via a connecting portion that is a fluid channel separate from and parallel to the pipes of the network section 120. The connecting portion connects a first connection point at a first end 121 of the section 120 to a second connection point at a second end 122 of the section 120, the second connection point providing the laminar gas flow with a single path downstream of the section 120. The laminar gas flow follows a bifurcated path between the first and second connection points so that the pressure in the section 120 is reduced to below 30 mbar and more preferably below 15 mbar. The pressure within the section 120 can be determined using a pressure gauge.

The above connection method prevents impurities from contaminating the gas flow, and further has the advantage of not disrupting the normal operation of the network. Moreover, it removes the need to install costly new infrastructure through means such as hot tapping.

Once the pressure has been reduced in the network section 120, the reduced pressure is maintained in accordance with step 20 of the method for the duration of steps 30-60 until the leak 110 has been sealed.

Step 30 of the method comprises providing an aerosol containing an organic compound. The organic compound is a solute dissolved in a solvent such as water to provide a solution. The solution is then aerosolised to form the liquid aerosol 125.

The solution will firstly be described, and then the aerosolisation of the solution will be described in detail.

A wide range of organic compounds can be used as the solute for the solution, including glass forming compounds. A glass forming compound in this specification means a compound that can be dissolved in a solvent and forms a glassy solid as the solvent evaporates from the solution, which hardens into a glass. Glass is a non7 crystalline amorphous solid having a liquid-like disordered structure that is inert and non-porous with low permeability to gases and liquids. Glass therefore makes for a highly suitable sealing material to prevent fluids from seeping through leaks 110, particularly in pipes such as gas pipes, and to provide a resistant seal that remains strong for a significant amount of time.

Examples of the organic compound solute include saccharides, cellulose and polyols. A wide range of saccharides can be used, including monosaccharides, disaccharides and polysaccharides. In particular, sugars like trehalose, raffinose and sucrose can be used as the solute.

In order to provide the aerosol according to step 30, the method comprises providing the solution with a predetermined concentration and chemical composition. This is because the concentration and chemical composition of the solution determine the viscosity of the resulting aerosolised droplets 130, which in turn determines the rate at which the droplets 130 form the deposit 140. Droplets 130 can only form a seal 150 when the viscosity of the droplets 130 is ultra-viscous within the range of 10³-10⁷ Pa-s, and droplets 130 form a seal 150 more efficiently within the range of 10⁴-10⁶ Pa-s. This is because there is a bell-curve-like relationship between the viscosity of the droplets 130 and the success rate of forming the seal 150. If the droplets 130 do not fall within the ultra-viscous range, the seal 150 cannot form. This is because droplets 130 which are too viscous with viscosities above 10⁷ Pa-s form a dry powder that passes through the leak 110 without forming a deposit 140 at the site of the gas leak 110. Droplets 130 which are not viscous enough with viscosities below 10³ Pa-s combine at the site of the leak 110, but the resulting deposit 140 is too wet to provide sufficient strength to form a seal 150.

The method therefore comprises controlling the viscosity of the droplets 130 by predetermining the concentration and chemical composition of the droplets 130, so that the stable viscosity of the droplets 130 falls within the ultra-viscous range of 10³10⁷ Pa-s and more preferably within the range of 10⁴-10⁶ Pa-s to provide leak-sealing droplets 130, in which the stable viscosity of the droplets 130 is the steady viscosity value reached between the droplets 130 and their local environment. These leaksealing droplets 130 can then coagulate to form a deposit 140. For example, the solution may include a sucrose solute dissolved in water at a concentration in the range of 1-6 M, and more preferably within a range of 1.5-3 M.

The concentration of the solution that is aerosolised also determines the size of the resulting droplets 130. This is because more solvent evaporates from more diluted solutions than more concentrated solutions, so that the resulting droplets 130 have a smaller diameter than those from more concentrated solutions. It is preferable that the droplets 130 have a diameter in the range of 1-4 pm.

Droplets 130 having a diameter of 1-4 pm provide a good balance between the longevity of the aerosol in the pipe 100 and the effectiveness of the droplets 130 in sealing a leak 110. Droplets 130 having a diameter of 1-4 pm are small enough to be carried by the gas through a substantial distance of the pipe 100, for example around 500 - 1000m, as gravity does not cause them to drop out of the laminar gas flow to a significant extent over these distances. Additionally, droplets 130 of this size are large enough to seal leaks 110 of the size typically found in gas pipes effectively. If the droplets 130 were too small then it would take a larger number of droplets 130 to seal the leak 110 so the sealing method would be less effective. Furthermore, droplets 130 of this size are convenient to generate with a variety of aerosol equipment.

In order to predetermine the concentration correctly to form leak-sealing droplets 130 having a viscosity within the ultra-viscous range of 10³-10⁷ Pa-s and more preferably within the range of 10⁴-10⁶ Pa-s, the method preferably comprises ascertaining the humidity within the network section 120 containing the leak 110. This is because an inverse correlation exists between the humidity of the local environment and the stable viscosity of the droplets 130. As the humidity of the local environment increases, the viscosity of the droplets 130 decreases.

In terms of the concentration of the droplets 130 of the aerosol, diluted solutions result in more humid environments than concentrated solutions, since a higher proportion of solvent has been evaporated during the aerosolisation process. Therefore, diluted solutions provide less viscous droplets 130 than concentrated solutions for a given humidity.

The humidity is also dependent on the chemical composition of the solution. With varying gas phase relative humidity, particles formed from different chemical components show distinct relationships in the amount of water they retain. As water is a plasticiser, they consequently exhibit differing dependencies of viscosity on the relative humidity.

In one example, the relative humidity in the section 120 of the network is adjusted to fall within the range of 45-55% RH by predetermining the concentration and chemical composition of the droplets 130. Droplets 130 containing 2 M sucrose solution can form deposits 140 when the humidity is within the range of 45-55% RH in the network section 120 containing the leak 110.

In one embodiment, before forming the aerosol according to step 30 of the method, a first humidity logger 160 is fitted to a pipe upstream of the leak 110 and a second humidity logger 161 is fitted to a pipe downstream of the leak 110, as shown in figure 5. An operator can then take readings from both the first and second humidity loggers 160,161 in order to ascertain whether the humidity is homogeneous throughout the network section 120 containing the leak 110, and also whether and by how much the humidity needs to be adjusted to form leak-sealing droplets 130.

Once the level of humidity in the network section 120 containing the leak 110 has been determined, the concentration and chemical composition of the solute is predetermined and the aerosol is formed according to step 30 of the method.

The aerosolisation of the solution will now be described.

The solution is aerosolised using an atomiser, such as the TSI Model 9302 atomiser, or an airbrush. An aerosol device 170 for both generating and introducing the liquid aerosol 125 into the pipe 100 is shown in figure 6. The aerosol device 170 comprises a housing 171 containing an atomiser 172 and a supply port 173 for introducing the liquid aerosol 125 into the interior of the pipe 100. A first reservoir 174 supplies compressed gas into both the atomiser 172 and the housing 171, in which the gas supplied into the housing 171 is a diluting gas feed 175. A second reservoir 176 supplies the solution into the atomiser 172. A concentrated aerosol 177 is generated by the atomiser 172 and released into the housing 171. The concentrated aerosol 177 is then diluted in the housing 171 by the diluting gas feed 175 to form the liquid aerosol 125 before being supplied into the pipe 100 through the port 173.

The gas from the first reservoir 174 is preferably sourced from the normal gas flow in another section of the gas network. This helps to prevent impurities from contaminating the gas flow throughout the network.

The aerosol device 170 is set up to introduce the liquid aerosol 125 into the network section 120 upstream of the site of the leak 110 in accordance with step 40 of the method. This may involve installing an entry port 180 onto a pipe upstream of the leak 110 for introducing the liquid aerosol 125 into the pipe 100. The solution undergoes a rapid increase in viscosity as the solvent evaporates during the aerosolisation process and, on entry into the pipe 100, the liquid aerosol 125 stabilises within the environment of the network section 120 as the viscosity of the droplets 130 plateaus and reaches a steady value. The liquid aerosol 125 then flows through the network section 120 towards the site of the leak 110, as shown in figure 2.

As discussed above, the viscosity of the droplets 130 is determined by the concentration and chemical composition of the droplets 130. However, the viscosity of the droplets 130 can also be controlled once they have been introduced into the network section 120 by adjusting the humidity in accordance with step 50 of the method, if required.

Step 50 of the method comprises adjusting the humidity by introducing a stream of gas that has a controlled humidity. The stream of gas is sourced from the gas flow elsewhere in the network and may be compressed to a desired pressure, as required. For example, the stream of gas may be sourced from a section of the network that excludes the pipe 100 containing the leak 110. The stream of gas is contained in a canister, which is connected via a port 190 to a pipe upstream of the leak 110. The canister supplies the stream of gas directly into the pipe and adjusts the humidity levels as required in at least the network section 120 containing the leak 110, as shown in figure 5.

The stream of gas has a predetermined humidity level determined by the level of humidity adjustment required. For example, if the humidity logger readings indicate that the network section 120 containing the leak 110 is too humid to produce leaksealing droplets 130, the stream of gas is dehumidified as required to provide a dry gas. The canister feeds the dry gas into the pipe, which reduces the humidity in the network section 120. Alternatively, if the humidity logger readings indicate that the section of the network 120 containing the leak 110 is too dry to produce leak-sealing droplets 130, the stream of gas is humidified as required to provide a humid gas and then fed into the pipe to increase the humidity in the network section 120. In practice, the domestic gas supply is generally a dry source of gas, so it is likely that the humidity within the network section 120 will need to be increased to form leak-sealing droplets 130.

Temperature sensors and/or pressure loggers can be positioned on the pipe to relay temperature and/or pressure readings to the operator in some embodiments. In other embodiments, the humidity loggers 160,161 may be adapted to relay temperature and/or pressure readings as well as humidity readings to the operator.

Controlling the viscosity of the droplets 130 by adjusting the humidity within the network section 120 is particularly advantageous in gas systems where gas leaks have to be differentiated from the holes and branches of pipes in customer supply equipment. The humidity is adjusted to optimise the viscosity of the droplets 130 only in sections 120 of the network that contain the leaks 110. Elsewhere in the network, the humidity can be adjusted to prevent a seal 150 from forming. In this way, the humidity control is a means to 'switch on' the invention by providing the conditions for leak-sealing to occur. Therefore, the droplets 130 can be introduced into any part of the network that can transport droplets 130 to the site of the leak 110 without interfering with the normal operation of customer supply equipment.

The relative humidity within the network section 120 can also be adjusted by installing a humidifier and a dehumidifier onto pipes in the network section 120 to give the operator precise control over the humidity of the network section 120. However, predetermining the concentration and chemical composition of the droplets 130 is a more cost effective method of adjusting the viscosity and humidity within the network section 120 than installing a humidifying and dehumidifying system onto the network.

In practice, the leak-sealing droplets 130 having viscosities falling within the optimal viscosity range of 10³-10⁷ Pa-s and more preferably within the ultra-viscous range of 10⁴-10⁶ Pa-s can only form a deposit 140 upon collision with other droplets 130 or with the surfaces of the pipe 100, as shown in figure 3. As a result, the leak-sealing droplets 130 do not form a substantial deposit 140 while flowing through the pipes in the network section 120.

The pressure differential at the leak 110 itself however causes droplets 130 to divert from the laminar flow direction towards the leak 110. The resulting turbulent flow at the site of the leak 110 causes at least some of the droplets 130 to combine with each other and bond to the inner surfaces of the pipe 100 surrounding the leak 110 to form a deposit 140. The deposit 140 then grows in size as more droplets 130 collide with it and coagulate, until it substantially covers the fissure of the gas leak 110 in accordance with step 60 of the flow diagram of figure 1.

Once the deposit 140 has been formed at the site of the gas leak 110, the deposit 140 dries and solidifies to form a seal 150, as shown in figure 4. The seal 150 is effectively impermeable, as a result of its non-crystalline structure. Furthermore, the deposit 140 hardens over time, thereby growing stronger as it dries.

It is preferable to provide a seal 150 that has a permanent effect. One way of providing a permanent seal 150 is with the use of an acrylate compound.

According to an embodiment, the method comprises adding an acrylate, such as a cyanoacrylate compound. The cyanoacrylate compound is initially vapourised using for example an evaporator device. While the deposit 140 is solidifying into a glass seal 150, the resulting acrylate vapour is introduced into a pipe upstream of the site of the leak 110. When the acrylate vapour comes into contact with the deposit 140, its constituent particles bond with the deposit 140 to provide a fast-setting and permanent adhesive. Once the deposit 140 which now contains both the acrylate and the glass forming compound has solidified into a glass seal 150, the resulting seal 150 is effectively impermeable and permanent.

Once the seal 150 has been formed, step 70 of the method is carried out to increase the pressure in the network section 120 containing the leak 110 back to its normal operating pressure. Step 70 is only carried out if steps 10 and 20 were performed.

Step 70 comprises removing the connecting portion that connects the first and second connection points. The laminar gas flow is then fully directed through the network section 120 containing the sealed leak 110, which causes the pressure in the network section 120 to increase from the reduced pressure below 30 mbar back to its normal operating pressure.

The network section 120 then resumes normal operation with the leak 110 efficiently and effectively sealed.

Figure 5 shows the system for carrying out the method of the first preferred 5 embodiment. In order to set up the system, the connection points used to reduce the pressure in the network section 120 containing the leak 110 are at the first and second ends 121,122 of the network section 120 and are separated by a length spanning 5001000 m. The first and second humidity loggers 160, 161 are fitted upstream and downstream of the site of the leak 110, respectively. An entry point 180 for the aerosol device 170 to introduce the liquid aerosol 125 into the network section 120 is installed on a pipe upstream of the leak 110, and may be either upstream or downstream of the first humidity logger 160. An entry point 190 for the stream of gas having a controlled humidity is upstream of the entry point 180 of the liquid aerosol 125 in this embodiment, but may also be positioned downstream of the entry point 180 of the liquid aerosol 125.

The foregoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention as defined by the claims.

Claims

1. A method of sealing a leak in a pipe, the method comprising introducing a liquid aerosol into the pipe, wherein the liquid aerosol comprises ultra-viscous droplets of a solution, a solute of the solution comprising an organic compound.

2. The method of any one of the preceding claims, wherein the solute comprises a glass forming compound.

3. The method of any one of the preceding claims, wherein the solute comprises one of a saccharide and a polyol.

4. The method of claim 3, wherein the solute is one of a monosaccharide, a disaccharide, a trisaccharide and a polysaccharide.

5. The method of claim 4, wherein the solute is one of raffinose, trehalose, sucrose and cellulose.

6. The method of claim 1 or 2, wherein the solute is a sugar.

7. The method of claim 5 or 6, wherein the solution has a concentration within the range of 1-6 M.

8. The method of claim 7, wherein the solution has a concentration within the range of 1.5-3 M.

9. The method of any one of the preceding claims, wherein a solvent of the solution comprises water.

10. The method of any one of the preceding claims, comprising adjusting the viscosity of the droplets to fall within the range of 103-107 Pa-s.

11. The method of claim 10, comprising adjusting the viscosity of the droplets to fall within the range of 104-106 Pa-s.

12. The method of any preceding claim, comprising adjusting the humidity of at least a section of the pipe.

13. The method of claim 12 comprising adjusting the humidity to within the range of 45-55% RH in the section of the pipe that contains the leak.

14. The method of claim 12 or 13 comprising introducing a stream of gas having a controlled humidity from a source into the pipe, wherein the humidity of the stream of gas is different to the humidity of the gas in the section of the pipe.

15. The method of claim 14 comprising one of humidifying and dehumidifying the stream of gas prior to introducing the stream of gas into the pipe.

16. The method of any one of the preceding claims comprising introducing an acrylate compound into the pipe.

17. The method of claim 16, wherein the acrylate compound is introduced in the form of a vapour.

18. The method of claim 17, further comprising vapourising the acrylate compound.

19. The method of any one of the preceding claims comprising forming a deposit containing the organic compound on a surface of the pipe.

20. The method of claim 19, wherein the deposit is formed on a surface of the pipe surrounding the site of the leak.

21. The method of any one of the preceding claims, wherein the pipe is a gas pipe.

22. The method of any one of the preceding claims, further comprising aerosolising the solution.

23. The method of any one of the preceding claims comprising reducing the differential pressure in at least the section of the pipe that contains the leak prior to introducing the liquid aerosol into the pipe.

24. The method of claim 23, wherein the differential pressure is reduced to below 30 mbar.

25. The method of claim 23 or 24 comprising maintaining the reduced pressure in at least the section of the pipe that contains the leak until the leak has been sealed.

26. The method of one of claims 23-25 comprising increasing the differential pressure in at least the section of the pipe that contains the leak after the leak has been sealed.

27. A sealant system for sealing a leak in a pipe, the sealant system comprising the pipe and an aerosol device connected to the pipe, wherein the aerosol device is adapted to aerosolise a liquid to form an aerosol, and the aerosol device is further adapted to introduce the aerosol into the pipe.

28. The sealant system of claim 27, wherein the aerosol device comprises an atomiser.

29. The sealant system of claim 28, wherein the atomiser is adapted to generate a concentrated aerosol, and the aerosol device further comprises:

a housing containing the atomiser, the housing for diluting the concentrated aerosol;

a first reservoir adapted to store a gas; and a second reservoir adapted to store a solution containing an organic compound; wherein the first reservoir is connected to the housing and the atomiser, and the second reservoir is connected to the atomiser.

30. The sealant system of any one of claims 27-29 further comprising a source of gas and a humidity adjustment device, wherein the humidity adjustment device is adapted to adjust the humidity of the gas from the source, and the source is adapted to introduce the gas having a controlled humidity into the pipe.

31. The sealant system of claim 30, wherein the humidity adjustment device comprises at least one of a humidifier and a dehumidifier.

32. The sealant system of any one of claims 27-31 comprising at least one humidity logger adapted to monitor the humidity of the pipe.

33. The sealant system of any one of claims 27-32 comprising a temperature sensor adapted to monitor the temperature of the pipe.

34. The sealant system of any one of claims 27-33 further comprising at least two connection points in fluid communication with the pipe and a fluid channel separate from the pipe connecting the connection points, the leak located between at least two of the connection points.

35. A gas pipe comprising a seal covering a leak, wherein the seal is provided on an inner surface of the gas pipe, and the seal comprises a glass forming compound.

36. The gas pipe of claim 35, wherein the seal comprises a glass material.

37. A gas pipe comprising a seal covering a leak, wherein the seal is provided on an inner surface of the gas pipe, and the seal comprises one of a saccharide and a polyol.

38. The gas pipe of any one of claims 35-37, wherein the seal further comprises an acrylate.

39. A method of sealing a gas leak in a gas pipe substantially as hereinbefore 10 described with reference to Figs. 1-6.

40. A sealant system for sealing a gas leak in a gas pipe substantially as hereinbefore described with reference to Figs. 5 and 6.

15

41. A gas pipe comprising a seal covering a gas leak substantially as hereinbefore described with reference to Fig. 4.

Intellectual

Property

Office

Application No: GB 1616490.7