AU2012101045A4

AU2012101045A4 - Gas leak prevention device

Info

Publication number: AU2012101045A4
Application number: AU2012101045A
Authority: AU
Inventors: Hideo Ueno
Original assignee: Sanfreund Corp
Current assignee: Sanfreund Corp
Priority date: 2012-07-12
Filing date: 2012-07-12
Publication date: 2012-08-16
Anticipated expiration: 2020-07-12

Abstract

The present invention provides a gas leak prevention device that prevents gas leak from occurring by detecting gas leak due to degradation or corrosion of a pipe in which gas such as propane gas, town gas, natural gas flows with ease and by increasing the strength of the pipe. The gas leak prevention device that is provided includes a gas pipe (a pipe that is used for gas), fiber reinforced plastics that covers the outer peripheral of the pipe to prevent gas leak from the pipe from occurring, wire that is provided between the pipe and the fiber reinforced plastics, a pressure sensor that is provided between the pipe and the fiber reinforced plastics and at an end of the wire, and informing means for informing of the occurrence of gas leak when the pressure sensor detects a level of the gas pressure greater than a predetermined threshold. 31-3 31-2 30-3 31-1 30-2 30-1

Description

P/00/009A Section 29 AUSTRALIA Patents Act 1990 INNOVATION PATENT SPECIFICATION Invention Title: GAS LEAK PREVENTION DEVICE Applicant: Sanfreund Corporation The invention is described in the following statement: 1 7019 GAS LEAK PREVENTION DEVICE Background of the Invention Field of the Invention [0001] The present invention relates to a gas leak prevention device that prevents gas leak from a pipe in which propane gas or town gas, further or natural gas flows from occurring. Description of the Related Art [0002] Nowadays, propane gas or town gas is widely used and is supplied through a pipe that is provided in a house such as a apartment house, a plant or the like. Further, natural gas such as ethane, methane, or the like may be transferred through piping equipment such as pipeline. In such cases, a huge social issue including accident or the like may be arisen when gas leak occurs. [0003] Hence, a gas leak alarm device that may be one of gas leak detectors has been widely used so far. The gas-leak alarm device sounds an alarm or turns an alarm lamp on to inform people around the device when gas leak is detected. [0004] For example, Patent Document 1 (Japanese Laid-Open Patent Application 2002-109656) discloses a gas leak detection system that uses a buttery powered gas leak detector. The gas leak detection system as a invention comprises one or more gas leak detector(s) and a monitor that is communicatively connected to the detector(s), and determines occurrence of gas leak based on the gas density that is detected by the gas leak detector(s) to inform people around the detector(s) about occurrence of the gas leak. [0005] In general, gas leak may be occurred when a pipe becomes old and is rusted due to a long term use. Hence, it would be preferable that gas leak is prevented from occurring before gas leak is detected by a gas leak detector conventionally. However, it would be a demanding task to make examinations of occurrence of pipe crack, measurements of the thickness of a pipe, or the like periodically. Further, it would be impossible to make an examination of pipe periodically when the pipe is laid under the ground. Summary of the Invention [0006] The present invention provides a gas leak prevention device that prevents gas leak from occurring by detecting gas leak due to degradation or corrosion of a pipe in which gas such as propane gas, town gas, natural gas flows with ease and by covering Fiber Reinforced Plastics (PRP) on the pipe. (0007] The gas leak prevention device that is provided includes a gas pipe (a pipe that is used for gas), fiber reinforced plastics that covers the outer peripheral of the pipe to prevent gas leak from the pipe from occurring, wire that is provided between the pipe and the fiber reinforced plastics, a pressure sensor that is provided between the pipe and the fiber reinforced plastics and at an end of the wire, and informing means for informing of occurrence of gas leak when the pressure sensor detects a level of the gas pressure greater than a predetermined threshold. [0008] Further, the gas leak prevention device is provided, wherein the gas leak prevention device includes a gas pipe (a pipe that is used for gas), fiber reinforced plastics that covers the outer peripheral of the pipe to prevent gas leak from the pipe from occurring, wire that is provided between the pipe and the fiber reinforced plastics, gas sensors that are provided on an upper half portion of the pipe at a predetermined interval, and informing means for informing of occurrence of gas leak when the pressure sensor detects a level of the gas pressure greater than a predetermined threshold. [0009] Due to the above mentioned configuration of the gas leak prevention device, gas leak due to degradation or corrosion of a pipe in which gas such as propane gas, town gas, natural gas, flows can be prevented from occurring by the fiber reinforced plastics that covers the pipe. Further, even if gas leak from the pipe is occurred, accidents such as explosions due to gas leak would be prevented from occurring by detecting and informing of gas leak using a pressure sensor or a gas sensor which is provided between the pipe and the fiber reinforced plastics. Brief Description of the Drawings [0009] Fig. 1 is a diagram illustrating a piping configuration of a gas pipe at which a gas leak prevention device according to the present embodiment is provided; Fig. 2 is a cross sectional view of the piping configuration and a gas leak detecting structure; Fig. 3(a) is a cross sectional view of the pipe; Fig. 3(b) is an enlarged view of portion indicated by a dotted circle A in Fig. 3(a); Fig. 4 is a cross sectional view of the pipe taken along a line B-B in Fig. 3(a); Fig. 5 is a cross sectional view illustrating a structure of an end portion of the pipe according to the first embodiment; Fig. 6(a) is a diagram illustrating a network configuration of a lead wire that is provided on a peripheral surface of a steel pipe; Fig. 6(b) is a diagram illustrating a spiral configuration of a lead wire that is provided on a peripheral surface of a steel pipe; Fig. 7(a) is a diagram illustrating a cover structure of fiber reinforced plastics (FRP); Fig. 7(b) is a diagram illustrating a cover structure of fiber reinforced plastics (FRP); Fig. 7(c) is a diagram illustrating a cover structure of fiber reinforced plastics (FRP); Fig. 8 is a diagram illustrating a gas leak detecting structure according to the second embodiment; and Fig. 9 is a diagram illustrating a gas leak detecting circuit. Description of the Preferred Embodiments [0010] Hereinafter, embodiments of the present invention will be explained in detail referring to the drawings. [0011] (First Embodiment) Fig. 1 is a diagram illustrating a piping configuration of gas pipes at which a gas leak prevention device according to the present embodiment is provided. In this figure, a gas ring 2, gas heaters 3, 4, 5 which use town gas are installed in a house 1, and the town gas is supplied via the gas pipes. In this example, the gas ring 2 is installed within a kitchen 6 at the first floor, the gas heater 3 is installed within a room at the first floor, the gas heaters 4 and 5 are installed within rooms at the second floor. [0012] Town gas is supplied via a main pipe 9 and a pipe 10 which are laid in the ground under the road 8, and the pipe 10 is connected to the main pipe 9 via a joint member (not shown) . Further, the pipe 10 is connected to a pipe 12 in the house 1 via a gas meter 11. The gas meter 11 measures and indicates the amount of gas supplied to the house 1 via the pipe 10. [0013] Town gas is supplied to the gas ring 2 and the gas heaters 3, 4, 5 via the pipe 12: for example, gas is supplied to the gas heater 2 via a pipe 13 that is branched from the pipe 12, gas is supplied to the gas heater 3 via a pipe 14 that is branched from the pipe 12, and gas is supplied to the gas heaters 4 and 5 via a pipe 15 that is branched from the pipe 12. [0014] A detection sensor 17 is provided at the end of the pipe 12 to detect occurrence of gas leak. The detection sensor is connected to a detection monitor 19 via a signal cable 18 to detect occurrence of gas leak from the pipe 12. [0015] Fig. 2 is a diagram illustrating, in particular, a cross sectional structure of the pipe 10 and 12 and a gas leak detecting structure in the above mentioned structure of the system. As discussed above, town gas is supplied to the pipe 10 from the main pipe 9 via the joint member, and then to the gas ring 2 and the gas heaters 3, 4, 5 via the pipe 12 and the gas pipes 13, 14, 15. As shown in Fig. 2, the pipes 10 and 12 have a double structure, for example, the pipes 10 and 12 are steel pipes to which plating is applied, and each of the steel pipes that serves as base pipes is covered or coated by fiber reinforced plastics (FRP). [0016] Fig. 3(a) is a cross sectional view of the pipes 10 and 12 (hereinafter the pipe 12 is representative of the pipes 10 and 12), and Fig. 3(b) is an enlarged view of portion indicated by a dotted circle A in Fig. 3(a). As already discussed, the pipes 12 has the double structure, that is, a steel pipe 20 is covered or coated by fiber reinforced plastics (FRP) . Further, as shown in Fig. 3(b), a lead wire 22a is provided between the steel pipe 20 and the FRP 21. This lead wire 22a is a wire to form a predetermined space (gap) between the steel pipe 20 and the FRP 21, and is provided on an upper surface 20a of the steel pipe 20 with a linear shape. [0017] The portion indicated by a dotted circle A2 in Fig. 3(a) also has the same or similar structure with that discussed above, that is, a lead wire is provided between the steel pipe 20 and the FRP 21. This lead wire is a wire to form a predetermined space between the steel pipe 20 and the FRP 21, and is provided on a lower surface 20b of the steel pipe 20 with a linear shape. [0018] Fig. 4 is a cross sectional view of the pipe 12 taken along a line B-B in Fig. 3 (a). An upper portion of the pipe 12 has a structure in which the lead wire 22 is provided between the steel pipe 20 and the FRP 21, as explained referring to Fig. 3(b). A lower portion of the pipe 12 has a structure in which the lead wire 22 is provided between the steel pipe 20 and the FRP 21 and the FRP 21 is doubly covered or coated. That is, the steel pipe 20 is covered or coated by a first FRP 21a and a second FRP 21b covers or coats on a FRP 21a. A primer 23 is painted between the FRP 21a and the FRP 21b. [0019] The FRP 21 that is used in the present example is a thin sheet that includes epoxy acrylate resin as base material and is strengthened by glass fiber, and whose upper and lower surfaces are covered by clear plastic films. The painting of the primer 23 is aimed to improve adhesiveness of a member to which the FRP 21 is adhered by flattening the surface of the member, to improve easiness of removing the FRP 21, easiness of sticking the FRP 21, and easiness of degassing when a bubble is generated between the FRP 21 and the primer 23 after the primer 23 is coated and dried. The primer 23 may be made of epoxy acrylate resin that is cured by mixing accelerant or hardener. [0020] The FRP 21a covering the peripheral surface of the steel pipe 20 has a surface that is no other than a surface of the plastic film formed on the surface of the FRP 21a, which is made by covering the first FRP 21a around the steel pipe 20, and then covering the second FRP 21b having a predetermined length to adhere to the first FRP 21a. According to such the structure, a space is formed between the steel pipe 20 and the second FRP 21a to provide a path of leaked gas, as discussed below. [0021] Next, installation processes of the pipe 12 having the above mentioned double structure (double coating structure) will be explained. First, cleaning of the surface of the old pipe 12 (the steel pipe 20) is performed. After this cleaning, a pressure inspection of the steel pipe 20 is conducted to wipe off dust, dirt or the like from the outer surface of the pipe 20. [0022] Next, an attachment process of the lead wire 22 is performed. In the attachment process of the lead wire 22, the lead wire 22 is wired from the upper end to the lower end of the pipe 20 along the pipeline to guide leaked gas to the detection sensor 17 when gas leak is occurred. The lead wire 22 is provided on the upper surface and the lower surface of the pipe 20 with the linear shape and some points on the lead wire 22, which are separated with each other at a predetermined interval, are fixed (secured) to the surface of the pipe 20 so as to prevent the lead wire 22 from bending. This fixing may be carried out using the same material with that of which the lead wire 22 is made. [0023] Next, an installation process of the detection sensor 17 is performed. This detection sensor 17 is provided at the end portion of the pipe 12, as discussed above, to detect occurrence of gas leak. The fixing of the detection sensor 17 can be carried out in the same or similar way in which the lead wire 22 is fixed (secured), and insulating material is wound around the detection sensor 17 to isolate the detection sensor 17 from the pipe 20 certainly. [0024] Fig. 5 is a cross sectional view illustrating a structure of an end portion of the pipe 12 (the steel pipe 20) As shown in Fig. 5, the detection sensor 17 includes a piezoelectric device 24 and a detector 25, and transmits a gas leak detection signal toward the detection monitor 19 via the signal cable 18 in the basis of a voltage generated in the piezoelectric device 24. The piezoelectric device 24 has a structure in which a piezoelectric substrate is sandwiched by two electrode, and generates a voltage in response to a pressure on the piezoelectric substrate. [0025] The detection circuit 25 includes a storage circuit that stores a reference voltage and a comparison circuit, and the storage circuit stores a predetermined voltage in advance. This voltage may be chosen to be set referring to a gas pressure of the gas that may be leaked from the pipe 20 due to a crack appeared in the pipe 20. Hence, for example, when the pipe 20 has been used for a long years sufficient to appear a crack at which gas leak occurs, leaked gas flows in the space between the pipe 20 and the FRP 21 and increases the gas pressure in that space. The gas pressure may be detected by the piezoelectric device 24, and the piezoelectric device 24 outputs a voltage in accordance with the gas pressure, for example. Hence, when the voltage exceeds the predetermined reference voltage, the comparison circuit (the detector 25) outputs the gas-leak detection signal toward the detection monitor 19. [0026] The end portion of the pipe 12 to which the detection sensor 17 is attached has the following structure. That is, after the lead wire 22 and the detection sensor 17 have been attached to the pipe 20, the FRP 21 winds around the steel pipe 22. In more detail, the plastic film that covers the surface of the FRP 21 should not be removed, and the FRP 21 (21a) winds around the steel pipe 22, while the FRP 21 (21a) covers the upper end portion of the pipe twice. And then, the plastic film that covers the upper end portion of the pipe is removed to apply the primer to the surface of the upper end portion of the pipe, and the FRP 21 (21a) is adhered to the pipe. These processes bring to form a double covered portion where both of the FRP 21a and the FRP 21b covers the surface of the pipe. [0027] In this case, the double covered portion has a value of thickness of the FRP 21 (thicknesses of the FRP 21a and FRP 21b are added) should be greater than a predetermined value. Hence, a double pipe structure composed of the steel pipe 20 and the FRP 21 is formed by the attachment process of the FRP 21, as discussed above, and a predetermined space (microspace) is formed between the steel pipe 20 and the FRP 21 and the lead wire 22 is provided in the predetermined space (microspace) . Further, in order to prevent gas leak from the from the gap (microspace) from occurring, the primer 23 is applied to the end surfaces of the FRP 21 (21a, 21b) at the end portion of the steel pipe 20, as discussed above. The primer 23 may be applied to the surface of the steel pipe 20 and a FRP 21 (21c) is provided to cover the surface of the primer 23. [0028] Next, an airproof test for the gap (microspace) is carried out. This test includes processes of entering a needle for the airproof test into the FRP 21 and injecting a test gas into the gas. After the airproof test, the needle is extracted from the FRP, and a needle hole formed when the needle enters into the FRP is covered by attaching the FRP 21. Next, ultraviolet light is applied to cure the FRP 21. [0029] Next, electrical wiring work is carried out. In this work, the signal cable that is connected to the detection sensor 17 (detector 25) for detecting the leaked gas, the detection sensor 17 (detector 25) having been provided with the pipe, wires to the detection monitor 19, that is, the signal cable 18 extends to the detection monitor 19 to connect the signal cable 18 to the detection monitor 19. The signal cable 18 is protected by an electrical conduit 26. [0030] The gas-leak detection monitor 19 has a LED display, a speaker, or the like, and, for example, turns a LED on and sounds a alarm that has been recorded in advance when the detection sensor 17 (detector 25) detects occurrence of gas leak. [0031] Although the above explanations have particularly dealt with the pipe 12, the pipe 10 has a similar or the same structure with the pipe 12, that is, has the structure in which the steel pipe 20 is covered by the FRP 21. Further, the lead wire 22 is provided (wired) between the steel pipe 20 and the FRP 21. [0032] In the above mentioned piping configuration, operations for preventing gas leak from occurring and detecting occurrence of gas leak will be explained. A crack may be appeared in the pipe 10 or the pipe 12 when the pipe 10 or the pipe 12 has been deteriorated due to use of the pipe 10 or the pipe 12 for long years, and gas may be leaked from the pipe 10 or the pipe 12 through the crack. However, in the double pipe structure of the present example, the peripheral surface of the pipe 12 is covered by the FRP 21 to prevent gas from being leaked to an outside space. Therefore, accidents due to gas leak such as town gas leakage would be prevented from occurring. [0033] The gas leaked from the pipe 10 or the pipe 12 is accumulated in the space (gap) formed between the steel pipe 20 and the FRP 21. Then, when occurrence of gas leak continues, the leaked gas fills the space formed between the steel pipe 20 and the FRP 21 and increase the pressure in the space. The detection sensor 17 that is provided at the end portion of the pipe 12 receives the pressure so that the value of voltage generated by the piezoelectric device 24 changes. Hence, when the value of voltage exceeds the reference voltage, the comparison circuit 25 (detector 25) outputs the gas leak detection signal toward the detection monitor 19. [0034] In this case, The gas-leak detection monitor 19 turns the LED on (blinks the LED on and off) and sounds the alarm from the speaker to inform people about occurrence of the gas leak.

[0035] The above mentioned processes makes it possible to detect occurrence of gas leak, and the double pipe structure according to the present example makes it possible to detect occurrence of gas leak easily, while preventing gas form being leaked to outside space, so that an effective means of the safety administration can be obtained. [0036] In the present embodiment, the device has a configuration that detects leakage of town gas. However, the similar or the same configuration can be applied to prevention of gas leak wherein the gas is not only town gas but also propane gas, natural gas, or the like. [0037] Further, in the structure of the present example, the pipe 20 is the steel pipe. However, the similar or the same structure can be applied to not only a steel pipe but also another type of pipe including a polyethylene pipe, hard polyvinyl chloride steel pipe. [0038] In the above explanation of the embodiment, the lead wire 22 is provided along the upper and lower surface of the steel pipe 20. However, the lead wire 22 can be provided in a configuration shown in Fig. 6(a) or Fig. 6(b). Fig. 6(a) is a diagram illustrating a network configuration of lead wire 22 that are provided on a peripheral surface of a steel pipe 20, and this configuration makes it possible to detect occurrence of gas leak easily due to a space (gap) formed by serving the lead wire 22 as a spacer. Fig. 6(b) is a diagram illustrating a spiral configuration of lead wire 22 that are provided on a peripheral surface of a steel pipe 20, and this configuration makes it possible to detect occurrence of gas leak easily due to a space (gap) formed by serving the lead wire 22 as a spacer. [0039] Further, it may be possible to adopt a double coating structure of the FRP (fiber reinforced plastics) different from the structure discussed above. While Fig. 7(a) is a diagram illustrating the double coating structure discussed above, structure shown in Fig. 7(b) or Fig. 7(c) can be adopted. For example, in the case shown in Fig. 7(b), the structure is formed by the following processes. First, ends of FRP 21 (21a) may be joined at the upper portion of the pipe, and this joint portion 32 and its neighborhood may be applied by coating of the primer 33. And the FRP 21 (21b) may covers on the joint portion 32 finally. In this case, the overlapped length of the FRP 21a and the FRP 21b may be 5cm, for example. [0040] In the case shown in Fig. 7(c), the FRP 21a may be provided such that the FRP 21a covers only a part of the surface of the steel pipe 20, that is, keeps a non-covered part 20' (for example, 3/4 of the surface of the steel pipe 20) un-covered, in the process in which the FRP 21a is provided. Next, the non covered part 20' is covered by the FRP 21b in the process in which the FRP 21b is provided so that there are two parts where the FRP 21 is double covered. In this case, the primer 36 can be applied and the overlapped length of the FRP 21a and the FRP 21b may be 5cm, for example. Further, in this case, the FRP 21a can be molded in advance, for example, in a factory, and the molded FRP 21a can be mounted at the site of the work. [0041] In the above explanation of the embodiment, the piping system in which town gas is supplied to the house 1 has been explained. However, the similar or the same system can be applied to a building that uses town gas, such as a apartment house, a plant or the like. Further, the similar or the same system can be applied to a building that uses gas that is not only town gas but also propane gas, natural gas, or the like [0042] The gas leak prevention device according to the present example can be applied to a pipe that is placed near a coast so that it may easily corroded particularly. In the above discussion, the structure in which the plastic film is not removed has been adopted in the process for providing the FRP 21 with the steel pipe 20. However, it is possible to remove the plastic film such that the FRP 21 is attached to the surface of the pipe 20 directly. [0043] (Second Embodiment) A second embodiment according to the present invention will be explained. [0044] The present embodiment is essentially based on the piping configuration shown in Fig. 2, but has a configuration in which gas detection sensors are provided at the pipe 10 and/or the pipe 12 at a predetermined interval. That is, the configuration according to the present embodiment has a basic structure in which, as shown in Fig. 3 and Fig. 4, the FRP 21 covers the surface of the steel pile 20, but has an additional structure in which the gas detection sensors are provided on the inner steel pipe 20 at a predetermined interval. The interval may be exemplified by about 1mm. [0045] Fig. 8 illustrates an example in which gas sensors 30 are provided at the steel pipe 20 at a predetermined interval. The gas detection sensor 30 may be a semiconductor gas sensor whose internal resistivity changes in response to gas detection. The gas detection sensor 30 is provided at the upper portion of the steel pipe 20 because the gas used in the gas detection sensor 30 such as ethane gas, methane gas, propane gas, or the like which has a lighter weight than that of air. [0046] As discussed above, the gas detection sensors 30 are provided at the steel pipe 20 at a predetermined interval, and each of the gas detection sensors 30-1, 30-2, ... is conncted to a corresponding signal cable 31-1, 31-2, .... These signal cables 31 1, 31-2, ... are connected to the gas leak detection device and carry detection signals (resistivity changes) indicating occurrence of gas leak from the gas detection sensors 30-1, 30-2, [0047] Fig. 9 is a diagram illustrating a gas leak detecting circuit. As shown in Fig. 9, the gas leak prevention device 32 includes gas leak detection circuits 32-1, 32-2, ..., each of which corresponding to one of the gas detection sensors 30-1, 30-2, to detect occurrence of gas leak based on detection signals from the gas detection sensors 30-1, 30-2,. [0048] For example, the gas leak detection circuit 32-1 includes a transistor Trl, a resistor Rl, rl, and the gas .4 detection sensor 30-1, and in the gas leak detection circuit 32-1 the voltage value V of a power source E is divided using the resistivity of the gas detection sensor 30-1 and the resistivity of the resistor R1 and the gas leak detection signal (output 1) is outputted from the collector terminal of the transistor Trl when the resistivity of the resistor Rl exceeds a predetermined value. Similarly, the gas leak detection circuit 32-2 includes a transistor Tr2, a resistor R2, r2, and the gas detection sensor 30-2, and in the gas leak detection circuit 32-2 the voltage value V of a power source E is divided using the resistivity of the gas detection sensor 30-1 and the resistivity of the resistor R1 and the gas leak detection signal (output 1) is outputted from the collector terminal of the transistor Trl when the resistivity of the resistor R1 exceeds a predetermined value. [0049] Each gas leak detection circuit 32-3, 32-4, ..., 32-n has similar or the same structure, that is, when the corresponding gas detection sensor 30-3, 30-4, ..., 30-n detects occurrence of gas leak, the resistivity is varied to output the corresponding outputs (output 3, output 4, ..., output n) from one of the gas leak detection circuits 32-3, 32-4, ..., 32-n and inform people of the occurrence of gas leak. In informing of the occurrence of gas leak, the LED is turned on (the LED is blinked on and off) and the alarm is sounded from the speaker to inform people about occurrence of the gas leak [0050] The present example makes it possible to detect occurrence of gas leak, and the double pipe structure according to the present example makes it possible to detect occurrence of gas leak easily, while preventing gas form being leaked to outside space, so that an effective means of the safety administration can be obtained. Further, in this example wherein each of the output 1, output 2, ..., output n is received by the corresponding LED, it is possible to obtain information about the position near which gas leak occurs. That is, because the gas detection sensors 30-1, 30-1, ..., 30-n are provided at the predetermined interval, it is possible to obtain the information 4 A about the position near which gas leak occurs from the position of the LED that is turned on so that the position near which gas leak occurs can be obtained easily. [0051] Therefore, the position on the pipe 12 at which gas leak occurs can be known easily so that the pipe 12 can be repaired easily. [0052] In Fig. 9 above, the transistors Trl, Tr2, ..., Trn are used. However, it is possible to use switching elements such as field effect transistors (FETs) or the like. Further, it is possible to use not only the semiconductor gas sensor but also the other types of gas sensor as the gas sensor with additional element to the above-mentioned gas leak detection circuit and/or modification of the above-mentioned gas leak detection circuit. [0053] In the present embodiment, the device has a configuration that detects leakage of town gas. However, the similar or the same configuration can be applied to prevention of gas leak wherein the gas is not only town gas but also propane gas, natural gas, or the like. Further, in the structure of the present embodiment, the pipe 20 is the steel pipe. However, the similar or the same structure can be applied to not only a steel pipe but also another type of pipe including a polyethylene pipe, hard polyvinyl chloride steel pipe.

Claims

1. A gas leak prevention device, comprising: a pipe that is used for gas; fiber reinforced plastics that covers the outer peripheral of the pipe to prevent gas leak from the pipe from occurring; wire that is provided between the pipe and the fiber reinforced plastics; a pressure sensor that is provided between the pipe and the fiber reinforced plastics and at an end of the wire; and informing means for informing of the occurrence of gas leak when the pressure sensor detects a level of the gas pressure greater than a predetermined threshold.

2. A gas leak prevention device, comprising: a pipe that is used for gas; fiber reinforced plastics that covers the outer peripheral of the pipe to prevent gas leak from the pipe from occurring; wire that is provided between the pipe and the fiber reinforced plastics; gas sensors that are provided on the upper half portion of the pipe at a predetermined interval; and informing of the occurrence of gas leak when the pressure sensor detects a level of the gas pressure greater than a predetermined threshold.

3. The gas leak prevention device according to claim 1, wherein the wire is provided along the upper surface and the lower surface of the pipe.

4. The gas leak prevention device according to claim 2, wherein the wire is provided along the lower surface of the pipe, and a signal cable extended from the gas sensor is provided along the upper surface of the pipe

5. The gas leak prevention device according to claim 1, wherein the wire has a network configuration that is provided on a peripheral surface of the pipe.

6. The gas leak prevention device according to claim 1, wherein the wire has a spiral configuration that is provided on a peripheral surface of the pipe.

7. The gas leak prevention device according to any one of claims 1, 3, 5, and 6, wherein the pressure sensor is provided at the end of the pipe.

8. The leak prevention device according to claim 2 or 4, wherein the gas sensor outputs a change in the resistivity via the signal cable and detects occurrence of gas leak from a position on the pipe near or at where the gas sensor is provided based on the change of the resistivity. 1,-