Fixing structure for metal pipe

Abstract

[Problem] To provide a fixing structure for fixing a metal pipe to a metal gas box while ensuring airtightness inside the gas box, wherein, a drop in the temperature of a process gas flowing through the metal pipe extending from the inside of the gas box to the outside is suppressed. [Solution] A fixing structure 1 for fixing a metal pipe 3 extending from the inside of a gas box 2 to the outside through an opening 2a provided in the gas box 2 comprises a plate-like member 6 which is fixed to an outer surface of the gas box 2 to close the opening 2a and has a portion through which the metal pipe 3 passes. The plate-like member 6 has a thermal conductivity lower than that of the metal pipe 3.

Description

Metal piping fixing structure

[0001] The present invention relates to a fixing structure for metal piping, and more particularly to a structure for fixing metal piping extending from a gas box to the gas box.

[0002] Conventionally, a gas supply system has been used to supply process gas to a process chamber in semiconductor manufacturing equipment, etc. The gas supply system integrates flow rate controllers and valves provided on multiple gas supply lines and houses them in a gas box (see, for example, Patent Document 1).

[0003] Gas boxes are used to improve safety by preventing leakage into the surrounding area in the event of a gas leak. Gas boxes may be connected to an exhaust path to prevent leaked gas from leaking into the surrounding area, or may be filled with an inert gas such as nitrogen gas to prevent leaked process gas from reacting with air.

[0004] The gas box is required to have a suitable airtightness to deal with gas leaks from the gas supply system. The gas box is formed as a housing by welding metal plates such as aluminum plates, for example.

[0005] A vaporizer may also be housed inside the gas box. The vaporizer generates high-temperature process gas by heating and vaporizing the liquid raw material. To prevent the high-temperature process gas from re-liquefying in the metal piping before reaching the process chamber, a heater is installed along the metal piping that transports the process gas, and the heater is further covered with insulating material to prevent the temperature of the process gas from dropping.

[0006] Japanese Patent Application Laid-Open No. 2021-52110

[0007] As described above, when handling high-temperature gas, the metal pipe is covered with a heater or a heat insulating material to prevent the temperature of the high-temperature gas from dropping.

[0008] However, despite this, the temperature of the gas passing through the metal pipe sometimes drops below the desired temperature.

[0009] SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a fixing structure for a metal pipe that can suppress a drop in the temperature of a high-temperature process gas flowing inside the metal pipe extending from a gas box.

[0010] In order to solve the above problems, the present inventors have conducted extensive research and discovered the cause of the temperature drop of high-temperature process gas in metal piping and a means for solving the problem.

[0011] As described above, when handling high-temperature gas, it is possible to prevent the temperature of the high-temperature gas from dropping to some extent by covering the metal pipe with a heater or heat insulating material. However, it is necessary to fix the metal pipe to the gas box so that the metal pipe does not sway sideways due to impact, vibration, etc., while suppressing gas leakage from the gas box. If the metal pipe is fixed to the gas box using fixing hardware such as a flanged pipe joint, it is not possible to install a heater on the metal pipe at the fixed portion.

[0012] Therefore, the heat of the high-temperature process gas passing through the metal piping escapes from the metal piping to the fixed part between the metal piping and the gas box.The heat is then transferred from this fixed part to the metal gas box and dissipated.As a result, the temperature of the process gas in the metal piping drops.

[0013] Therefore, a fixing structure for metal piping according to an embodiment of the present invention is a fixing structure for fixing metal piping extending from the inside to the outside of a metal gas box through an opening provided in the gas box, and is provided with a plate-like member having a passage for the metal piping and fixed to the outer surface of the gas box to close the opening, and the plate-like member has a thermal conductivity lower than that of the metal piping.

[0014] The plate-shaped member may be made of a super engineering plastic.

[0015] The plate-shaped member may be made of polyether ether ketone.

[0016] The plate-like member may be made of a synthetic resin having a heat resistance of 150° C. or higher.

[0017] The metal pipe may be covered with a heater.

[0018] The plate-shaped member may be made of synthetic resin, and may be provided with a metal fitting portion that fits into the opening.

[0019] A guide portion for guiding the fitting portion when it is fitted into the opening may be provided on a side edge of the fitting portion.

[0020] The fitting portion may be configured to surround the periphery of the metal pipe with a predetermined gap therebetween so as not to come into contact with the metal pipe.

[0021] According to the fixing structure for metal piping according to the embodiment of the present invention, it is possible to make the gas box airtight and properly fix the metal piping extending from the gas box, while suppressing heat radiation from the metal piping and suppressing a decrease in the temperature of the high-temperature process gas flowing inside the metal piping.

[0022] Fig. 3 is a cross-sectional view showing a fixing structure for metal piping according to one embodiment of the present invention. Fig. 4 is an exploded perspective view showing components of the fixing structure for metal piping according to one embodiment of the present invention. Fig. 5 is a perspective view of a plate-shaped member, which is one of the components shown in Fig. 2, viewed from the back side. Fig. 6 is a perspective view of a fitting portion, which is one of the components shown in Fig. 2, viewed from a direction different from that of Fig. 2. Fig. 7 is a perspective view showing an example of an upper gas box, which is a part of a gas box. Fig. 8 is an exploded perspective view of the components of the fixing structure for metal piping in Fig. 2, and a perspective view showing an upper gas box into which the components are incorporated.

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6, but the present invention is not limited to the embodiments described below.

[0024] 1 shows a state in which a metal pipe 3 is fixed to a gas box 2 by a fixing structure 1 for metal pipes according to an embodiment of the present invention. A gas processing device 4 to be incorporated into a gas supply system is housed inside the gas box 2. The gas box 2 is made of metal, preferably stainless steel. The metal pipe 3 is preferably formed of a stainless steel circular pipe that is corrosion-resistant against process gases. A joint 3a is provided at the tip of the metal pipe 3 for connecting to another metal pipe or the like.

[0025] The gas processing device 4 may have various configurations. The gas processing device 4 may include a flow control device and a vaporizer. However, the gas processing device 4 is not limited to this embodiment, and may be any gas supply line component that may cause a gas leak, such as a metal pipe, a flow path block, or a fluid element (such as a valve). In addition, although not shown, wiring connected to a flow control device or the like housed in the gas box 2 is drawn out from the gas box 2.

[0026] Furthermore, the metal pipe 3 extending from the inside to the outside of the gas box 2 may be a raw material inlet pipe through which a gaseous or liquid raw material flows in, a gas delivery pipe through which a raw material gas (process gas) vaporized in a vaporizer is delivered, or a filler gas supply pipe through which a filler gas is supplied to the gas box 2. Although only one metal pipe 3 is shown in Fig. 1, a plurality of metal pipes may be provided. The metal pipe 3 through which the high-temperature gas vaporized in the vaporizer flows may be kept warm by a heater 5 covering the metal pipe 3.

[0027] Typically, an inert gas (here, nitrogen gas) is supplied from a filler gas supply pipe to the inside of the gas box 2 so that the pressure is equal to or higher than atmospheric pressure. This prevents the leaked gas from reacting with oxygen in the air even if gas leaks from the gas processing device 4. To prevent ambient air from flowing into the gas box 2, it is desirable to maintain the pressure of the inert gas inside the gas box 2 equal to or higher than the external pressure (typically atmospheric pressure).

[0028] The gas box 2 is provided with an opening 2a through which the metal pipe 3 passes. The metal pipe 3 extends from the inside to the outside of the gas box 2 through the opening 2a. A plate-like member 6 having a passage 6a (FIG. 1) through which the metal pipe 3 passes is fixed to the outer surface of the gas box 2 so as to close the opening 2a.

[0029] The plate-like member 6 is disposed with its bottom surface facing the outer surface of the gas box 2, and is fixed to the gas box 2 with screws 7 (FIG. 6). By fixing the plate-like member 6 to the gas box 2, the gap between the inner peripheral surface of the opening 2a and the outer peripheral surface of the metal pipe 3 is closed.

[0030] 2, the plate-like member 6 may be composed of a pair of first and second plate-like portions 6b and 6c arranged to sandwich the outer circumferential surface of the metal pipe 3. A recessed groove 6e for forming a passage portion 6a for the metal pipe 3 is formed on the joint surface between the first and second plate-like portions 6b and 6c. The outer circumferential surface of the metal pipe 3 is supported by the inner circumferential surface of the passage portion 6a, thereby preventing lateral movement and rattle of the metal pipe 3. The plate-like member 6 does not have to be a two-piece type as in the illustrated example, but may be a single plate with a single hole that serves as the passage portion 6a through which the metal pipe 3 passes.

[0031] The gas box 2 shown in FIG. 1 can be separated into an upper gas box 2b and a lower gas box 2c. FIG. 5 is an exploded perspective view of the upper gas box 2b, and FIG. 6 is a perspective view showing an example of a configuration in which the fixing structure 1 is provided in the upper gas box 2b. The upper gas box 2b in the illustrated example is composed of a first portion 2b1 and a second portion 2b2. The upper gas box 2b is formed by arranging the first portion 2b1 and the second portion 2b2 adjacent to each other and joining them airtightly. Note that the terms "upper" and "lower" are used herein for convenience of explanation, but may differ from the actual upper and lower positions.

[0032] An opening 2a is formed at the joint between the first portion 2b1 and the second portion 2b2. In the illustrated embodiment, recessed regions are provided at the joint edges of both the first portion 2b1 and the second portion 2b2. The opening 2a is formed by combining these recessed regions. Although not shown, a recessed region may be provided only in one of the first portion 2b1 and the second portion 2b2. Here, a gas box divided into upper and lower portions is used to properly enclose the metal pipe 3 extending from the gas processing device 4 and bending thereto after being housed in the lower gas box 2c as shown in FIG. 1. However, a one-piece gas box with the opening 2a may also be used as long as it is configured to allow the metal pipe 3 to pass through. The opening 2a of the gas box 2 is preferably rectangular, but may have other shapes.

[0033] To further enhance airtightness, the plate-shaped member 6 preferably has a stepped portion 6g (FIG. 2) around the passage portion 6a on the surface opposite the gas box 2, and an annular sealing member 9 made of an elastic material is housed in the stepped portion 6g. A pressing member 10 that presses the annular sealing member 9 can be fixed to the plate-shaped member 6. As the pressing member 10 presses the annular sealing member 9 inside the stepped portion 6g, the annular sealing member 9 elastically deforms within the stepped portion 6g and presses against the plate-shaped member 6 and the metal pipe 3, thereby sealing between the plate-shaped member 6 and the metal pipe 3. The pressing member 10 can be formed of a metal plate made of stainless steel or the like with a thickness of, for example, about 1 to 2 mm.

[0034] The holding member 10 is fixed to the plate-like member 6 with screws 11 (FIG. 6). The holding member 10 can be composed of a first holding portion 10a and a second holding portion 10b arranged to sandwich the metal pipe 3 from both sides. Semicircular recesses 10a1 and 10b1 are formed at the joining edges of the first holding portion 10a and the second holding portion 10b, respectively, to form a circular passage through which the metal pipe 3 passes. The holding member 10 can also be composed of a single plate.

[0035] The first and second holding portions 10a, 10b are positioned so that the joint between the first and second plate portions 6b, 6c intersects with the joint between the first and second plate portions 6b, 6c. The first holding portion 10a is fixed to the first and second plate portions 6b, 6c with screws 11. The second holding portion 10b is also fixed to the first and second plate portions 6b, 6c with screws 11. As a result, the first and second holding portions 10a, 10b, the first and second plate portions 6b, 6c are directly or indirectly connected to each other and integrated. Through holes 10c for passing the screws 11 are formed in the first and second holding portions 10a, 10b, and screw holes 6f for threading the screws 11 are formed in the first and second plate portions 6b, 6c.

[0036] The plate-like member 6 preferably has a certain thickness, for example, 3 to 10 mm, in order to support the outer circumferential surface of the metal pipe 3 and suppress rattle of the metal pipe 3. On the other hand, the pressing member 10 only needs to be able to press the annular sealing member 9 and elastically deform it, and a metal plate that is thinner and smaller than the plate-like member 6 can be suitably used.

[0037] The plate-like member 6 is made of a material having a thermal conductivity lower than that of the metal pipe 3. This makes it possible to suppress heat transfer from the metal pipe 3 to the plate-like member 6 and to suppress a temperature drop of the high-temperature process gas inside the metal pipe 3.

[0038] On the other hand, when handling high-temperature process gas, it is preferable that the plate-shaped member 6 has high heat resistance capable of withstanding the temperature of the high-temperature process gas. Therefore, a super engineering plastic, which is a high-performance resin with extremely high heat resistance and mechanical strength, is preferably used for the plate-shaped member 6.

[0039] Super engineering plastics are plastics that have a heat resistance of generally 150°C or higher and are suitable for generating high-temperature process gases using a vaporizer. Known super engineering plastics include PPS (polyphenylene sulfide), PSU (polysulfone), PPSU (polyphenylene sulfone), PAR (polyarylate), PES (polyethersulfone), PEI (polyetherimide), PAI (polyamideimide), PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane polymer), PEEK (polyetheretherketone), PEK (polyetherketone), PEKK (polyetherketoneketone), and PI (polyimide).

[0040] Among super engineering plastics, PEEK (polyether ether ketone) is particularly preferred because its continuous use temperature (also known as continuous heat resistance temperature) is approximately 240°C to 250°C. Furthermore, the thermal conductivity of standard PEEK material (test method ASTM D177) is 0.25 W / (m·K), which is much lower than the 236 W / (m·K) of aluminum and the 16 W / (m·K) of stainless steel (SUS304).

[0041] The material of the plate-shaped member 6 is not limited to thermoplastic resins such as super engineering plastics, but may also be thermosetting resins such as epoxy resins and phenolic resins that are heat-resistant to high temperatures (150°C or higher). These synthetic resin materials generally have lower thermal conductivity than metal materials. Ceramics may also be used as the material of the plate-shaped member 6.

[0042] A fitting portion 8 that fits into the opening 2a is provided on the bottom surface of the plate-shaped member 6 so as to protrude from the bottom surface of the plate-shaped member 6. This fitting portion 8 can be formed to a size that allows it to be press-fitted into the opening 2a of the gas box 2.

[0043] When the plate-shaped member 6 is made of a resin material as described above, it is desirable to use a metal material for the fitting portion 8 and to screw the fitting portion 8 to the plate-shaped member 6. By making the fitting portion 8 out of a metal material in this way, even if the process gas leaks into the gas box, the process gas will not come into contact with the plate-shaped member 6 made of a resin material, and combustion can be prevented.

[0044] The fitting portion 8 can include a pair of first and second fitting portions 8a and 8b that are joined to each other. The first fitting portion 8a is fixed to the first plate-shaped portion 6b, and the second fitting portion 8b is fixed to the second plate-shaped portion 6c. Recesses 8a1 and 8b1 for passing the metal pipe 3 are formed on the joining surfaces where the first fitting portion 8a and the second fitting portion 8b are joined. The fitting portion 8 does not have to be two parts, the first fitting portion 8a and the second fitting portion 8b, but can also be configured as a single part by integrating these parts.

[0045] When the fitting portion 8 is made of a metal material, the recesses 8a1, 8b1 can be configured to surround the metal pipe 3 with a predetermined gap G ( FIG. 1 ) between the recesses 8a1, 8b2 and the metal pipe 3 so as not to come into contact with the metal pipe 3. This prevents heat transfer from the metal pipe 3 to the fitting portion 8, and suppresses a decrease in the temperature of the high-temperature gas flowing inside the metal pipe 3.

[0046] To position the fitting portion 8 relative to the plate-like member 6, a positioning protrusion 6h (FIG. 3) may be formed on the bottom surface of the plate-like member 6 (first plate-like portion 6b, second plate-like portion 6c), and recesses 8a2, 8b2 (FIG. 2) into which the protrusion 6h fits may be formed in the first fitting portion 8a and the second fitting portion 8b, respectively. A recess may be formed in the plate-like member 6, and a protrusion that fits into the recess may be formed in the fitting portion 8.

[0047] The recesses 8a2 and 8b2 are formed with through holes 8a3 and 8b3 through which screws 12 (FIG. 6) pass. Meanwhile, the protrusion 6h is formed with a screw hole 6i (FIG. 3) through which the screw 12 is screwed. By fitting the protrusion 6h into the recesses 8a2 and 8b2, the through holes 8a3 and 8b3 and the screw hole 6i are aligned. By passing the screw 12 through the through holes 8a3 and 8b3 and screwing it into the screw hole 6i, the fitting portion 8 is fixed to the plate-like member 6.

[0048] The pressing member 10 and the plate-like member 6 are fixed together with screws 11, and the plate-like member 6 and the fitting portion 8 are fixed together with screws 12, thereby integrating the pressing member 10, the plate-like member 6, and the fitting portion 8. In this integrated state, the fitting portion 8 is fitted into the opening 2a of the gas box 2, thereby positioning the plate-like member 6 for fixing relative to the gas box 2. This positioning aligns the through-hole 6d in the plate-like member 6 with the screw hole 2d (FIG. 5) in the gas box 2, and the plate-like member 6 can be fixed to the outer surface of the gas box 2 by passing a screw 7 through the through-hole 6d and threading it into the screw hole 2d (FIG. 5).

[0049] To facilitate fitting of the fitting portion 8 into the opening 2a of the gas box 2, a guide portion 8a4 ( FIG. 4 ) can be provided on a side edge of the fitting portion 8. By forming the guide portion 8a4 as a plate-like member that bends and stands up from the side edge of the plate-like fitting portion 8, the fitting portion 8 can be formed with an L-shaped cross section. The guide portion 8a4 can be provided with a tapered portion 8a5 at the corner of the tip end on the fitting side into the opening 2a to facilitate fitting. With this configuration, when fitting the fitting portion 8 into the opening 2a, the tapered portion 8a5 guides the guide portion 8a4 into the opening 2a. Then, by sliding the guide portion 8a4 while abutting against the edge of the opening 2a, the fitting portion 8 is fitted into the opening 2a while being guided by the guide portion 8a4, and the fitting portion 8 can be fitted into the opening 2a.

[0050] When the process gas flowing through the metal pipe 3 is a high-temperature gas, the metal pipe 3 can be covered with a heater 5 (FIG. 1) to prevent a drop in the temperature of the process gas. The heater 5 may be, for example, a jacket heater or a tape heater, and may be provided so as to cover the metal pipe 3 inside and outside the gas box 2, except for the area surrounded by the plate-like member 6. The temperature of the heater 5 is adjusted to a desired temperature (for example, 40 to 200°C) by an external temperature regulator.

[0051] A comparative test was conducted to measure the temperature change of gas passing through a metal pipe for an example of a fixing structure according to the present invention and a comparative example. The example used in the comparative test had the fixing structure shown in FIG. 6 , in which the plate-shaped member 6 was made of PEEK material and the metal pipe 3 was covered with a jacket heater. The comparative example used in the comparative test differed from the example only in that the plate-shaped member was made of aluminum. The gas box, metal pipe, and pressure member were all made of stainless steel. High-temperature gas (controlled at 130°C) was generated by a vaporizer in the gas box and flowed through the metal pipe. Temperature measurements were taken using a thermocouple attached to the outer surface of the metal pipe 3 near the plate-shaped member (point A in FIG. 1 ) outside the gas box 2. The temperature was 114.8°C for the comparative example and 126.7°C for the example. Therefore, by changing the material of the plate-shaped member from aluminum to PEEK, the temperature drop of the high-temperature gas flowing through the metal pipe was significantly suppressed. This is because the amount of heat that escapes from the high-temperature gas to the plate-like member in contact with the metal pipe is greater in the Comparative Example than in the Example. This shows that by forming the plate-like member from a material with a lower thermal conductivity than the metal pipe, it is possible to suppress the temperature drop of the high-temperature gas flowing inside the metal pipe.

[0052] As is clear from the above description, the fixing structure for metal piping according to the present invention makes the gas box airtight and properly fixes the metal piping extending from the gas box so that it does not rattle, while suppressing heat radiation from the metal piping and suppressing a decrease in the temperature of the high-temperature process gas flowing inside the metal piping, which can contribute to preventing re-liquefaction of the high-temperature gas flowing inside the metal piping.

[0053] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. For example, in the above-described embodiment, the plate-shaped member and the fitting portion are configured as separate bodies, but the plate-shaped member and the fitting portion may also be formed as an integrally molded product.

[0054] REFERENCE SIGNS LIST 1 Fixing structure 2 Gas box 3 Metal piping 4 Gas treatment device 5 Heater 6 Plate-shaped member 8 Fitting portion 8a4 Guide portion

Claims

1. A fixing structure for fixing metal piping extending from the inside to the outside of a metal gas box through an opening provided in the gas box, comprising a plate-shaped member having a passage for the metal piping and fixed to the outer surface of the gas box to close the opening, the plate-shaped member having a thermal conductivity lower than that of the metal piping.

2. The fixing structure for metal piping according to claim 1, wherein the material of the plate-like member is a super engineering plastic.

3. The fixing structure for metal piping according to claim 2, wherein the material of the plate-like member is polyether ether ketone.

4. The fixing structure for metal piping according to claim 1, wherein the material of the plate-like member is a synthetic resin having a heat resistance of 150°C or more.

5. The fixing structure for metal piping according to claim 1, wherein the metal piping is covered with a heater.

6. The fixing structure for metal piping according to claim 1, wherein the plate-like member is made of synthetic resin, and a metal fitting portion that fits into the opening is provided on the plate-like member.

7. The fixing structure for metal piping according to claim 6, wherein a guide portion for guiding the fitting portion to be fitted into the opening is provided on a side edge of the fitting portion.

8. A fixing structure for metal piping as set forth in claim 6, wherein the fitting portion is configured to surround the periphery of the metal piping with a predetermined gap therebetween so as not to come into contact with the metal piping.

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