AU2012100171A4 - Piping and method therefor - Google Patents

Abstract

An underground mine ventilation pipe and method of manufacture therefor is provided that is configured and adapted for being stiff enough to handle especially large vacuum pressures, while being lightweight to facilitate handling and installation. The pipe is comprised of an inner and an outer layer of carbon fibre separated by a core layer, preferably of honeycomb. The pipe is treated for fire retardancy. The pipe includes features for reducing static electricity build up on the pipe. This includes an electrical connection between the inner and outer layer of carbon fibre. iifl qrr _ T, C.,

Description

Regulation 3.2 AUSTRALIA PATENTS ACT, 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT ORIGINAL Name of Applicant: RIVERS CARBON TECHNOLOGIES LIMITED Actual Inventors: RIVERS, Graeme Mark Address for service in A J PARK, Level 11, 60 Marcus Clarke Street, Canberra ACT Australia: 2601, Australia Invention Title: Piping And Method Therefor The following statement is a full description of this invention, including the best method of performing it known to .

2 TECHNICAL FIELD The present invention relates to a pipe and method therefor. More particularly but not exclusively it relates to a ventilation pipe and a method of manufacture therefor. BACKGROUND OF THE INVENTION In underground mining, and in particular coal mining, ventilation pipes are used to ventilate zones close to the cutting face. Cutting faces may be at the seam face of mine production areas, or may be at the development face where development ends are being excavated. Ventilation can be required for a number of reasons. One of these reasons is to reduce the temperature at the cutting face by facilitating airflow to and/or from the cutting face. Deep underground (for example at about 4km underground in deep gold mines), virgin rock temperatures may reach 700 Celsius. Accordingly strong ventilation flows are required to ventilate the workings. Another reason is to remove dust or other hazardous materials, such as coal dust or explosive fmnes after a blast from the cutting face. In addition to causing black lung disease (anthracosis) if inhaled by miners, coal dust can be explosive when fine dust is mixed with air and ignited. The presence of coal dust from underground long-wall or room and pillar type coal mining can be explosive to a small spark. This nay be especially true if it is mixed with methane gas, -which may be released when mining coal seams. Explosive fumes remaining after blasting a cutting face can be toxic to workers. Ventilation may be provided by installing ventilation pipes. The ventilation pipes may produce a vacuum for sucking air at the cutting face into the ventilation pipes (for example where coal dust or fumes are being removed) or by blowing air out at the face (for example where only cooling is required). The volumes of air required to be transported by such ventilation pipes are generally large, as the volume of the cavity alongside the cutting faces may be large. Accordingly, the pressures inside the ventilation pipes are required to be relatively high, or very low (i.e. a vacuum) relative to the ambient air pressure in the cutting face. Accordingly, the ventilation piping must be able to handle such pressures. Further, the areas that such ventilation pipes are installed in require the length of the pipes to be extended regularly. Until the pipes have been extended to the newly blasted cutting faces, most other work may be halted. The longer it takes to install such ventilation 3 pipes, the longer production may be stalled, or work on extending development tunnels slowed. In mines, it is critical to stop production for as little as possible. Also, the speed at which development ends can be developed is critical, as a few hours delay every day, can add days, weeks or even months of time for a longer development tunnel. Such development tunnels can be critical to other aspects of a mine, such for providing ventilation outlets to production areas. Ultimately, delay on the development of development tunnels can result in project and hence production delays for a mine, with enormous cost consequences. Further, ventilation pipes used currently are made of metal such as steel. The size of these pipes makes them heavy, which makes The installation of such pipes more hazardous. The injuries resulting from handling such heavy pipes can also result in ongoing costs to a mine for the treaunent and rehabilitation of injured persons. In some instances, the costs arising from such injuries may run into millions of dollars, when time off work and resulting loss of productivity is taken into account. In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art. It is an object of the present invention to provide a pipe and method therefor which overcomes or at least partially ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice. SUMMARY OF THE INVENTION (US Same) In a first aspect the present invention may be said to broadly consist in a pipe, suitable for ventilation of an underground mine, said pipe comprising a pipe body comprising o an inner layer comprising at least one layer of moulded carbon fibre and resin; o an outer layer comprising at least one layer of moulded carbon fibre and resin; and o a core layer disposed intermediate the inner layer and the outer layer.

4 Preferably, the pipe further comprises a layer of glass fibre. Preferably, the pipe further comprises a layer of glass fibre having apertures in it that are small enough for the surface tension of the resin to seal the apertures when the resin is applied to the glass fiber layer during production of the pipe, to thereby provide a substantially airtight pipe when the resin sets. Preferably, at least one or more of the inner layer and the outer layer is treated for fire retardancy Preferably, the resin of at least one or more selected from the inner layer and the outer layer includes a fire retardant chemical. Preferably, the resin comprises a fire retardant chemical. Preferably, the fire retardant chemical is one or more selected from * aluminium trihydrate * barium Sulphate o organobromide compounds o aluninium hydroxide * magnesium hydroxide * hydromagnesite, * red phosphorus, and o boron compounds * organohalogen compounds and o organophosphorus compounds. Preferably, the outer layer is electrically connected to the inner layer to prevent static electricity differential between the pipes. Preferably, the pipe comprises an attachment formation for the pipe to be secured to a hanging wall and/or side wall of a tunnel. Preferably, the pipe comprises electrical coupling formations for electrically coupling one or more selected from the inner layer and the outer layer to earth. Preferably, at least one or more of the inner layer and the outer layer extends towards the other of the said at least one or more of the inner layer and the outer layer to make an electrical connection with said other. Preferably, the inner layer extends outwardly towards at least one end of the pipe to make an electrical connection with the outer layer. Alternatively, the outer layer extends inwardly towards at least one end of the pipe to make an electrical connection with the inner layer.

5 Preferably, the pipe comprises end formations. Preferably, the end formations are flanges. Preferably, the end formations reinforce the end of the pipe. Preferably, the pipe comprises complementary end formations that are configured and adapted to engage with the opposed end formations of a similar pipe. Preferably, the complementary end formations are flanges. Preferably, the complementary end formations are also reinforcing end formations. Preferably, the complementary end formations are also composed of carbon fibre. Preferably, the complementary end formations are reinforced. Preferably, the inner diameter of the pipe is in the range of between 300mm and 1500mim. More preferably, the inner diameter of the pipe is in the range of between 400mm and 1000mm. More preferably, the inner diameter of the pipe is in the range of between 500mm and 800mm. Most preferably, the inner diameter of the pipe is in the range of between 600mm and 750mm. Preferably, the pipe is between 1 and 5 meters long. Preferably, the pipe is between 2 and 3 meters long. Most preferably, the pipe is about 2.5 meters long. Preferably, the pipe is configured and adapted for withstanding a vacuum pressure of between -0,01 kPa to -0.3 kPa without collapsing inwardly.. More preferably, the pipe is configured and adapted for withstanding a vacumn pressure of between -0,03 kPa to -0.2 kPa without collapsing inwardly. More preferably, the pipe is configured and adapted for withstanding a vacuum pressure of between -0,05 kPa to -0.15 kPa without collapsing inwardly. Most preferably, the pipe is configured and adapted for withstanding a vacuum pressure of about -0,07 kPa without collapsing inwardly. Most preferably, the pipe is configured and adapted for withstanding a vacuum pressure of about -0,15 kPa without collapsing inwardly. Preferably, the pipe comprises visibility aids to assist their visibility underground. Preferably, the visibility aids include fluorescent bands. Preferably, the visibility aids include light reflective bands. Preferably, the core layer is composed of a honeycomb formation.

6 Preferably, the core layer is composed of a honeycomb formation around 5mm thick. Preferably, the honeycomb is Nomex " M honeycomb core. Alternately, the core layer is composed of foam. Preferably, the carbon fibre layer of one or more selected from the inner layer and the outer layer is comprised of at least one sheet of woven carbon fibre. Preferably, the woven carbon fibre weighs between 200grams/m and 800grams/m. Preferably, the woven carbon fibre weighs between 300grams/m 2 and 600grams/m Preferably, the woven carbon fibre weighs around 400grams/m 2 . Preferably, the pipe comprises an abrasion resistant layer at or towards an inner surface of said pipe. Preferably, the abrasion resistant layer is includes aramid fibres. Preferably, the aramid fibres are Kevlar@ fibres. Preferably, the pipe further comprises at least one or more candles configured and adapted to facilitate handling of the pipe for installation of the pipe underground. Preferably, the handles include a fastening formation for fastening the handle to one or more selected from the inner layer and the outer layer. Preferably, the fastening formation extends at least between the inner layer and the outer layer. Preferably, the fastening formation is composed of electrically conductive material Preferably, the fastening formation is a bolt and nut formation. Preferably, the pipe is configured and adapted for channelling air through it at rates of between I and 50m 3 /second. More preferably, the pipe is configured and adapted for channelling air through it at rates of between 4 and 35m 3 /second. More preferably, the pipe is configured and adapted for channelling air through it at rates of between 7 and 20m3/second. Preferably the end formations of the pips are configured and adapted to facilitate seamless flow of fluid through the pipe when the pipe is connected with similar pipes to provide a pipeline. Preferably, the carbon fibre layer is pre-impregnated with resin. Preferably, the resin is an epoxy resin.

7 According to another aspect, the invention may be said to consist in a method of manufacture of a pipe, said pipe being suitable for use underground for ventilation of an underground mine, said method comprising the steps of * applying a first layer of carbon fiber pre-impregnated with resin over a pipe mandrel; * applying a pipe mould casing over at least the first layer; and heating said sealed enclosure to form a cured pipe body. Preferably, the method comprises the step of a enclosing said mandrel, pipe mould and at least said first layer in a flexible airtight layer to form a sealed enclosure. Alternately, the mould casing seals against one selected from the friction minimising layer and the mandrel to form a sealed enclosure Preferably, the method comprises the step of * applying a core layer on the outside of the first layer before forming a sealed enclosure. Preferably, the method comprises step of * applying a second layer of carbon fiber pre-impregnated with resin over the core layer before forming a scaled enclosure. Preferably, the method further comprises the step of * applying a layer of glass fiber to the outside of the mandrels before curing the pre-inpregnated carbon fibre. Preferably, the method comprises the step of o applying a friction minimising layer to the outside of the mandrel before applying the first layer. Preferably, the mould casing comprises a plurality of mould casing pieces, and at least one of the mould casing pieces comprises at least one seal for sealing against at least one of the other mould casing pieces. Preferably, the mould casing comprises at least one seal for sealing against one or more selected from * against the mandrel, * against the friction minimising layer * between the mould casing pieces.

8 Preferably, the mould casing comprises a lip seal extending at least partially around an edge for sealing against said one selected from the mandrel and the friction minirriising layer. Preferably, the method comprises the step of * applying heat and pressure to the sealed enclosure in the autoclave to form a cured pipe body, Preferably, the method comprises the step of * inserting said sealed enclosure into an autoclave for providing high pressure and temperature for at least partially facilitating the curing of the pre impregnated resin to form a cured pipe body. Preferably, the carbon fibre layer is a woven layer. Preferably, the core layer comprises honeycomb core. Preferably, the honey comb core is 5mm thick. Alternately the flexible airtight layer does not enclose the mandrel. Preferably, at least one or more of die first and second layers of carbon fibre are impregnated with resin that is cured by heat and/or pressure. Preferably, at least one or more of the first and second layers of carbon fibre are impregnated with fire retardant chemicals. Preferably, the fire retardant chemicals include one or more selected from * aluminium trihydrate * barium Sulph ate * organobronide compounds * aluminium hydroxide * magnesium hydroxide * hydronagnesite, * red phosphorus, and * boron compounds * organohalogen compounds * organophosphorus compounds. Preferably, the flexible airtight layer is a plastic bag. Preferably, the method comprises the step of * assembling at least one end formations at or towards at least one end of the pipe mandrel.

9 Preferably, the method comprises the step of a assembling at least one end formations at or towards at least one end of the pipe mandrel before enclosing the mandrel, first layer, core layer, second layer and end formation(s) in a flexible airtight layer to form a sealed enclosure. Preferably, the outer diameter of the pipe mandrel is between 250 and 1450mm. More preferably, the outer diameter of the pipe mandrel is between 350 and 950mm. More preferably, the outer diameter of the pipe mandrel is between 450 and 750mm. Most preferably, the outer diameter of the pipe mandrel is between 550 and 600. Preferably, the pipe mandrel is between I and 5 meters long. Preferably, the pipe mandrel is between 2 and 3 meters long. Most preferably, the pipe mandrel is about 2.5 meters long. Preferably, the end formations are annular. Preferably, the end formations are configured and adapted to engage with the opposed end formations of a similar pipe. Preferably, the complementary end formations include flanges. Preferably, the complementary end formations are for reinforcing te ends of the pipe. Preferably, the complementary end formations are also composed of carbon fibre. Preferably, the complementary end formations are reinforced. Preferably, the method comprises the step of pre-moulding at least one or more of the end formations. Preferably, the method comprises the step of removing the cured sealed enclosure from the autoclave. Preferably, the friction minimising layer is composed of silicon. Preferably, the friction minimismg layer is one or more selected from a * a bag, * a sleeve, and * a sheet of material. Preferably, the friction mminising layer is composed of sihcon or any other suitable engineering choice of material.

10 Preferably, the method comprises the step of assembling at least one handle onto the cured Preferably, the method further comprises the step of securing attachment formation for the pipe to be secured to a hanging wall and/or side wall of a tunnel. Preferably, the attachment formations are secured to the cured pipe body. Alternately, the attachment formations are moulded into the cured pipe body. Preferably, the method comprises the step of attaching visibility aids to the pipe body. Preferably, the visibility aids are fluorescent and/or light reflective strips. Alternately, the visibility aids are be moulded into the cured pipe body. Preferably, the method comprises the step of layering the second layer of carbon fiber over the core layer so that it engages with the first layer. According to another aspect, the invention may be said to consist in a mine ventilation pipe for an underground mine, said ventilation pipe at least partially comprising moulded carbon fibre. Preferably, the ventilation pipe comprises an inner layer of carbon fibre, an outer layer of carbon fibre, and a core layer. Preferably, the core layer is a honeycomb core layer. Preferably, the ventilation pipe comprises handles. Preferably, the ventilation pipe is adapted and configured to engage in a complementary fashion with a similar adjacent pipe. Preferably, the ventilation pipe comprises a glass fibre layer. Preferably, the ventilation pipe comprises visibility aids for aiding visibility of the pipe in poor light conditions. Preferably, the ventilation pipe comprises reinforcing end formations. Preferably, the end formations are annular. Preferably, the ventilation pipe comprises fire retardant chemicals for increasing its fire retardancy. Preferably, the inner and outer layer of carbon fibre are electrically connected. Preferably, the inner diameter of the pipe is in the range of between 300mm and 1500mm. More preferably, the inner diameter of the pipe is in the range of between 400mm and 1000mm.

11 More preferably, the inner diameter of the pipe is in the range of between 500mm and 800mm. Most preferably, the inner diameter of the pipe is in the range of between 600mm and 750mm. Preferably, the pipe is between 1 and 5 meters long. Preferably, the pipe is between 2 and 3 meters long. Most preferably, the pipe is about 2.5 meters long. According to another aspect, the invention may be said to consist in a method as described in the accompanying specification. According to another aspect, the invention may be said to consist in a pipe a described in the accompanying specification. According to another aspect, the invention may be said to consist in a pipe obtainable by a method as described. According to another aspect, the invention may be said to consist in a pipe obtained by a method as described. According to another aspect, the invention may be said to consist in a mine ventilation pipe as described in the accompanying specification. A pipeline comprising a plurality of pipes as described, wherein the pipes are connected or connectable end to end. A mine comprising a pipeline as described. For the purposes of this specification, the term "plastic" shall be construed to mean a general term for a wide range of synthetic or semisynthetic polymerization products, and generally consisting of a hydrocarbon-based polymer. For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence. Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings. As used herein the term "and/or" means "and" or "or", or both. As used herein "(s)" following a noun means the plural and/or singular forms of the noun. The term "comprising" as used in this specification [and claims] means "consisting at least in part of'. When interpreting statements in this specification and claims which 12 include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner. The entire disclosures of all applications, patents and publications, cited above and below, if any, are hereby incorporated by reference. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. BRIEF DESCRIPTION OF THE DRAWINGS (US Same) The invention will now be described by way of example only and with reference to the drawings in which: Figure 1: shows a cross sectional view of a first embodiment of a pipe; Figure 2: shows a cross sectional view of a second embodiment of a pipe; Figure 3: shows a top perspective cutaway view of a pipe of figure 2, Figure 4: shows a mould casing, friction reducing layer and mandrel for a pipe; Figure 5: shows a cross sectional view of a pipe being moulded on a mandrel with a self sealing mould casing; and Figure 6: shows a cross sectional view of a pipe being moulded on a mandrel using a flexible airtight layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the above drawings, in which similar features are generally indicated by similar numerals, a pipe according to a first aspect of the invention is generally indicated by the numeral 100. In one embodiment now described, there is provided a pipe 100 suitable for ventilation of an underground mine, such as a coal mine, where coal dust is present in the air at the production or cutting face. The pipe 100 comprises a pipe body 110. The pipe body is made up of a number of layers. These layers include a first or inner layer 120 comprising at least one layer of moulded carbon fibre and resin; a second or outer layer 130comprising at least one layer of moulded 13 carbon fibre and resin; and a core layer 140 disposed intermediate the inner layer 120 and the outer layer 130. The inner layer 120 and the outer layer 130 is preferably comprised of at least one sheet of woven carbon fibre that extends around the circumference of the pipe 100. However, it is envisioned that layers f randomly aligned carbon fibre could also be used for the inner layer 120 and/or the outer layer 130. Woven carbon fibre layers having a weighting of between 200grams/m 2 and 800grains/mi. Are envisaged, and most preferably around 400grams/m 2 . The core layer 140 preferably is comprised of a stiff material, such as a Nomex @ honeycomb core of between 2 and 20 mm and most preferably about 5mm thickness, although this will depend on the particular qualities of the pipe 100., It is envisaged that alternative materials for the core layer 140 could be used, such as foamed plastic. The pipe 100 further comprises complementary configured annularly shaped reinforcing end formations 170. The end formations 170 are also envisaged as being of a carbon fibre composition, although this need not be the case, and possible reinforcement of the end formations 170 by reinforcing formations (not shown) are envisaged. Pipes 100 according to the invention are intended to be aligned longitudinally and engaged with adjacent similar pipes 100. The end formations 170 provide increased resistance to bucding where the pipes 100 are coupled together. Also, the end formations 170 a&b are complementarily shaped to be engageable with each other. In this way, the one end formation 170a can be snugly engaged with the opposing end formation 170 of an adjacent similar pipe 100. It is envisaged that the end formations 170 can include flanges 172 or any suitable engaging formations to this end. It is envisaged that the pipes will be relatively large, as they are can be configured and adapted to provide a passage for airflows in a range between 1m 3 /second and 50m/second. In some mines, legislation exists that sets out minimum amounts of ventilation to be provided at certain areas in a mine, such as development ends or long wall production faces, and it is envisaged that the typical flow rates through such pipes will be between 4 and 35m 3 /second, and most preferably between 7 and 20m 3 /second. In order to provide such high airflow rates, the pipes will generally be required to be large in diameter. In this regard, typical inner diameter sizes for the pipe 100 are envisaged as being between 300mm and 1500mm, more preferably, between 400mm and 1000mm, and even more preferably between 500mm and 800mm. Most preferably, the inner diameter of the pipe 100 is in the range of between 600mm and 750mm.

14 The use of carbon fibre allows for pipes 100 to be made longer, which means that longer stretches of piping can be installed mote quickly. This means that a development of certain length can have pipes installed down its length in a quicker time period. Also, the increased stiffness of carbon fibre reinforced with honeycomb allows for an increased resistance to buckling at longer lengths, while still being of manageable weight. However, while such benefits are available, it has been found by the applicant that the installation equipment used for mines are typically set up for installation of the commonly found heavier steel pipes, and therefore keeping the pipes 100 of the present invention to the typical lengths of steel pipes allows the mines to use the same installation equipment. This is expected to change as more mines take up the use of pipes 100 according to the invention. So while the length of the pipe 100 can be anywhere between 1 and 5 meters long (or even longer), the preferred length. of the pipe 100 is between 2 and 3 meters long, and most preferably is about 2.5m long. As was touched on previously, the increased stiffness of honeycomb reinforced carbon fibre allows for increased resistance to buckling or collapsing of the pipe where the pipe is sucking air into it by tneans of a vacuum pressure. While typically used steel pipes have to be as thin as possible in order to keep their weight down to prevent the occurrence of injuries from handling heavy pipes, the thinner the metal pipes are, the more likely they are to buclde when a vacuum i pressure is introduced inside the pipe. It has been found that pipes 100 according to the invention hare able to withstand very low vacuum pressures while still being relatively light and manageable. In particular the pipes 100 can be configured and adapted to withstand vacuum pressures of between -0,01 kPa to -0.3 kPa without collapsing inwardly, and more preferably between -0,03 kPa to -0.2 kPa without collapsing inwardly. Most commonly, vacuum pressures expected to be used are around -0,07 kPa, or 0,15 kPa, although it is envisaged that the increased capability of the pipes may result in vacuum pumps of increased power being introduced, resulting in better ventilated areas with less chance of ignition.. In a preferred embodiment, it is envisaged that the resin of the inner layer 120 and the outer layer 130 will include a fire retardant chemical that will at least partially facilitate the preventing of the pipe or part of it burning. It the most preferred embodiment, the fire retardant chemical wil be aluminium trihydrate, although it will be appreciate that many different fire retardant chemicals are available, with varying degrees of suitability for use underground. Examples of other chemicals include barium sulphate, organobromide 15 compounds, aluminium hydroxide, magnesium hydroxide, hvdromagnesite, red phosphorus, boron compounds, organohalogen compounds and organophosphorus compounds. In a preferred embodiment, the pipe 100 also includes a sealing layer 150 which is composed of a layer of preferably randomly aligned glass fibre. The glass fibre sealing layer 150 has small apertures in it relative to the carbon fibre inner layer 120 and outer layers 130. During manufacture of the pipe, 100 as described below, the resin flows through the glass fibre sealing layer 150 and the surface tension of the fluidised resin causes the resin to close the small apertures, so that when the resin cures, a substantially airtight pipe 100 is provided. It is envisaged that the sealing layer 150 could also be a plastic layer disposed on the inside of the pipe, or between the carbon fibre layers and the core layer. However such a layer would be subject to abrasion by particles, such as coal dust, if it lined the inside surface of the pipe 100, with the possible result that the air tightness may be compromised. Also, if sealing layer were a plastic layer and it was disposed between one of the carbon fibre layer and the core layer, the smooth texture of the plastic may cause delamination of the pipe. For this reason, a glass fibre sealing layer 150 is preferred, that is disposed in a position where it is shielded from abrasion by at least one layer of carbon fibre. An example of such a position would be intermediate the inner layer 120 and the core layer 140. In especially coal mines, static build-up is dangerous, as a spar] can cause an ignition. For this reason, the pipe 100 and preferably each of the inner layer 120 and the outer layer 130 must be electrically connected to earth. This electrical connection can extend independently from each layer, or via each other and through a common electrical coupling. Moulded carbon fibre material has relatively high electrical conductivity, which means that static electricity should not build up on the pipe 100 if it is connected to earth. It is envisaged that such a connection to earth vill be by means of attachment formations 190 by which the pipe 100 is able to be secured to a hanging wall and/or side wall of a tunnel. Such attachment formations 190 will typically be a metallic (e.g. steel) plate mounted on the pipe 100, with a hook or loop formation 192 or similar extending from it for engaging with a chain (not shown). The chain is then hung on a roof bolt by a connecting nut or other suitable means. Any electrical build up is either of the inner layer, outer layer or core layer is distributed via all three, and then discharged through the attachment formations. The attachment formation 190 could be secured onto the pipe body 110 or end formations 170, for example by nut and bolt formations 194, or could be moulded into the pipe body 110 during moulding of the pipe 100 as will be discussed below. It is also envisaged 16 that where the attachment fonnations used are not electrically conductive (e.g. ropes), then a separate dedicated electrical coupling such as a wire or cable (not shown) can be used In order to further assist the electrical coupling of the inner layer 120 and outer layers 130 to each other, it is envisaged that one of the inner layer 120 or the outer layer will extends towards and touch the other of the inner layer 120 and the outer layer 130 to make an electrical connection at an interface 125. The interface will preferably be provided towards one end of the pipe 100, and is shown in figures 1 and 2. In this regard the pipe 100 also includes one or preferably two handles 160 to facilitate the handling of the pipe 100 for example to move it into a position for installation, or for logistical handling, such as loading and unloading from a truck (not shown). Handles are generally necessary as the pipes 100 are generally relatively large in size (although not heavy). Where handles 160 are provided, it is envisaged that they could be connected to the pipe body 110 by means of fastening formations in the form of metallic nut and bolt formations 162 that extend between the inner layer and outer layer and through the core layer, thereby electrically coupling each of these to each other. In one preferred embodiment, it is envisaged that the pipes will be provided with visibility aids in the forn of fluorescent and/or reflective bands 180. The bands can be stuck onto the pipe 100 after the resin has cured, or can be moulded into the pipe body 110. In another embodiment not shown, it is envisaged that the inner layer 120 could include abrasion resistant fibres such as aranid fibres (e.g. Kevlar ® fibres) that present at an inner surface 112 of the pipe body. Alternately, an abrasion resistant layer 122, as shown in figure 6 could be provided inwardly of the inner layer 120. According to another aspect there is also provided a method of manufacture of a ventilation pipe 100 as described above. The pipe 100 will generally be manufactured according to the steps discussed below, and with reference to figures 4-6. Firstly a substantially cylindrical mandrel 500 is provided (as shown in figures 4-6). The mandrel 500 preferably includes a friction reducing layer 510 around its outer cylindrical surface. The friction reducing layer 510 is preferably in the form of a bag, sleeve or layer applied to the outer surface of the mandrel 500. The friction reducing layer 510 is also preferably composed of a material such as silicon, or other material having a low coefficient of friction,. The purpose of such a layer is to facilitate the removal of the cured pipe 100 from the mandrel after moulding of the pipe.

17 A first or inmer layer 120 of pre-impregnated carbon fiber (preferably of a woven configuration) is then applied to an outer surface the friction reducing layer 510. After this, a layer of glass fibre is applied to the outside of the first layer as a sealing layer 150. As has been mentioned above, the sealing layer 150 could be applied to the outside of the mandrel 500, and inside of the inner layer 120 as an alternative, or alternatively at. any stage of the process before curing. While the use of a sealed plastic layer has been envisaged, the applicant expects the presence of such a sealing layer to reduce the structural integrity of the pipe 100, and for this reason a glass fibre layer is preferred, with relatively small apertures in it, As will be described below, when the resin in the carbon fibre is heated and/or pressurized, the resin is caused to flow throughout the layers, including the sealing layer 150. During this process the resin will cover the glass fibre apertures, to effectively provide an airtight barrier. Without such a sealing layer, it has been found that the apertures provided between the woven carbon fibre layers are too large, with the result that the surface tension of the flowing resin does not effectively seal these apertures, leaving a carbon fibre pipe body 110 that has tiny "pinprick" apertures in it, and which are not conducive to effective operation of the pipe 100 as a ventilation pipe. After the sealing layer 150 is applied, a honeycomb core layer 140 as described above is applied to the outside of the sealing layer 150. After this, a second or outer layer 130 is applied to the outside of the core layer 140. It is envisaged that both the inner layer 120 and the outer layer 130 the layer of carbon fibre will be pre-impregnated with resin. It is further envisaged that the layer of carbon fibre will also be pre-impregnated with a fire retardant chemical such as aluminium tribydrate (or any of the chemicals mentioned above) in a fire retardant treatment. However, it is also envisaged that the a fire retardant chemical could be applied to one or both of the iner layer 120 and the outer layer 130 on application of these layers outside the mandrel 500 as welL. At this stage, complementary reinforcing end formations 170 a&b as described above are mounted at or towards an end of the cylindrically applied first or second layers. It will be appreciated that the end formations 170 a&b could also be applied in between the application of the inner layer 120 and the outer layer 130, depending on where the end formations 170 a&b are to be moulded relative to the inner laver 120 and the outer layer 130. In a preferred embodiment, it is envisaged that the end formations 170 a&b will be pre-moulded as annular rings, however this need not necessarily be the case, especially if the end formations 170 a&b include reinforcing formations (not shown) inside them. In such a 18 case, the resin within the end formations 170 a&b could be cured at the same time as the resin in the pipe body 110. It is envisaged that at this stage, plugs could be introduced to provide holes through the pipe body after curing of the resin for attachment of the handles 160 and/or attachment formations. A pipe mould casing 520 is then applied to the outside of the outer layer 130 and the end formations 170 a&b. In a preferred embodiment, the pipe mould casing 520 comprises two (or more) mould casing pieces 522&524 that together enclose the outer layer 130 and the end formations 170 a&b around their full circumference, and engage against and secure with each other as shown in figure 4. In another preferred embodiment, one or both of the mould casing pieces 522&524 are provided with lip seals 526 (shown in figure 5) that seal between the mould casing pieces 522&524 and/or the friction reducing layer 510. The mould casing pieces 522&524 can be provided with securing formations (not shown) that secure the mould casing pieces 522&524 to each other, and around the mandrel 500 and friction reducing layer 510. Preferably, the securing formations include lever-type formations that engage with hooks and both pull the mould casing pieces 522&524 towards each other as well as secure them to each other, to thereby facilitate the provision of a seal between the mould casing pieces 522&524 and the friction reducing layer 510. When the mould casing 520 is engaged in place, it forms a sealed enclosure between the friction reducing layer 510 and the pipe mould casing 520. During the resin curing process, the resin in the carbon fibre layers becomes fluidised, and flows throughout the extents of this sealed enclosure, Resin is typically cured by the application of heat, and/or the application of pressure, and preferably both. The best quality mouldings are typically achieved by inserting the sealed enclosure into an autoclave (not shown). In the autoclave, a high pressure is generated, while the temperature is raised. Where high pressure is used, means must be provided for the equalising of high ambient pressure in the autoclave and the pressure inwardly of the friction reducing layer 510. In this way, the inner layer 120, outer layer 130, core layer 140, and end formations 170 are pressed into the pipe mould casing 520 to create a more high quality finish, and to ensure better distribution of fluidised resin to all parts within the sealed enclosure.

19 To this end, an internal pressure equalisation channel 505 may be provided within the mandrel 500. These allows the ends of the mould casing pieces 522&524 to be sealed firmly against the friction reducing layer 510 and mandrel 500 without restricting or compromising the equalisation of pressure underneath the friction reducing layer 510. It is envisaged that the provision of a sealed enclosure could be by other means. As an example, a flexible airtight layer 530 (as shown in figure 6) could be provided in the form of a plastic sheet or sleeve that is extends over the pipe mould casing and seals against the friction reducing layer 510 or the mandrel 500. It could be pre-manufacnured as an endless sleeve, or it could be sealed against itself along its longitudinal edges, by means of a sealant such as silicon or other bonding substance such as glue. During the application of heat and pressure in the autoclave, the resin cures, and a cured pipe body 110 is formed within the pipe mould casing. It is envisaged that the mandrel 500 can have a slightly tapered profile, to facilitate the removal of the moulded pipe. The sealed enclosure, including the pipe mould casing 520 and moulded pipe body 110 is then removed from the autoclave, and the pipe mould casing 520 removed from the pipe body 110. Handles 160 are then mounted to the pipe body, by inserting bolt and nut formations through the holes where plugs have been included in the mould casing previously (or through hole that have been drilled in the pipe body). Attachment formations (not shown) can also be attached to the pipe body and/or the end formations at this stage. This would also typically be by inserting bolt and nut formations through the pipe body 110. It is envisaged that the handles 160 and/or attachment formations can be moulded into the pipe body during the curing process by locating these within the pipe mould casing before curing. Also, at this stage other ancillary components can be added. Such components include visibility aids (for example adhesive strips of material that have a light reflective surface). Alternately, light reflective strips could also be moulded into the pipe body 110 during the curing process. In this way, the applicant believes that a strong, lightweight ventilation pipe 100 can be provided that can be installed conveniently and with relatively lower injury rates, and at a relatively faster rate than would be the case with heavy steel pipes. The pipe 100 so provided also is capable of withstanding crumpling or collapse due to the high or low pressure to an 20 extent that is not possible with steel pipes, while retaining their convenient logistics and handling characteristics. Lastly, the pipes so provided also have good static electricity release characteristics that make it suitable for use in an underground mine, and can meet stringent underground fire retardancy laws. Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth. Although the invention has been described by way of example and with reference to particular embodiments, it is to be understood that modifications and/or improvements may be made without departing from the scope or spirit of the invention. In addition, where features or aspects of the invention are described in terms of Markush groups, those skilled in the art will recognise that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group. Without prejudice, and for convenience of reference, the following numerals are intended for use in reference to its associated feature:

Claims (5)

1. A pipe, suitable for ventilation of an underground mine, said pipe comprising a. a pipe body comprising i. an inner layer comprising at least one layer of moulded carbon fibre and resin; ii. an outer layer comprising at least one layer of moulded carbon fibre and resin; and iii. a core layer disposed intermediate the inner layer and the outer layer.

2. A pipe as claimed in claim 1, wherein the resin of at least one or more selected from the inner layer and the outer layer comprises a fire retardant chemical.

3. A pipe as claimed in any one of claims 1 to 2, wherein the outer layer is electrically connected to the inner layer to prevent static electricity differential between the pipes.

4. A method of manufacture of a pipe, said pipe being suitable for use underground for ventilation of an underground mine, said method comprising the steps of a. applying a first layer of carbon fiber pre-impregnated with resin over a pipe mandrel; b. applying a pipe mould casing over at least the first layer; and c. heating said sealed enclosure to at least partially cure the resin to form a cured pipe body.

5. A mine ventilation pipe for an underground mine, said ventilation pipe at least partially comprising moulded carbon fibre.