JP2006316987A - Glass pipe joint and glass pipe connecting technology - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe joint composed of glass as a whole and having high air-tightness. <P>SOLUTION: The joint is completely composed of glass, a structure of a face-seal pipe joint keeping air-tightness by butting seal faces of end portions of the pipes is applied as a structure of the joint, and the seal face is a plane having flatness of more than a degree for optical adhesion. To eliminate very small clearance between optically-adhered seal faces, the seal faces are fastened by a male screw means and a female screw means mounted coaxially with the pipe, and the seal faces of the joints are joined with proper force. When the piping is permanent piping, an optically-polished gasket is inserted according to necessity, and heat is applied to a joined portion after connecting the joints to adhere them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to piping technology for semiconductor manufacturing equipment, and particularly to joint technology for piping inside reaction equipment of semiconductor manufacturing equipment. In addition to semiconductor-related equipment, it also relates to high-quality piping technology used for chemical-related equipment and bio-related equipment. It also belongs to the field of glass piping technology, and is particularly related to high-quality piping technology that requires high airtightness.

  The background art of the present invention will be described.

  Glass is chemically stable and has a small coefficient of thermal expansion and heat resistance. Taking advantage of these characteristics, glass piping is used for transporting chemical substances and piping in a temperature environment, which is difficult with metal piping. The material of the glass piping used in the glass plant is borosilicate glass in which silicic acid is the main component and a small amount of boric acid is added. On the other hand, the material of the glass piping used in the semiconductor manufacturing apparatus is high-purity quartz glass. This is because when borosilicate glass is used in the semiconductor process, boric acid becomes an unintended impurity for the semiconductor to be processed.

  In many cases, piping is provided in the reaction apparatus of the semiconductor manufacturing apparatus, that is, in the reaction furnace in order to appropriately introduce the raw material gas necessary for the reaction to the reaction section. Inside a reaction apparatus of a semiconductor manufacturing apparatus, it is often impossible to use metal piping inside because it is generally heated to a high temperature or a corrosive gas is used. Furthermore, since the piping inside the reactor is exposed not only to the inner wall of the piping but also to the outer wall of the piping, and to the high temperature, the piping material and the piping joint material are Both inside and outside must be suitable for the piped environment.

  The region where the temperature in the furnace becomes high is the vicinity of the semiconductor substrate to be processed, the vicinity of the raw material generation unit, the preheating region, and the like, but in some cases, the entire furnace may be heated to a high temperature. At high temperatures, the corrosive gas becomes more reactive, making metal parts increasingly unusable. This is of course the reason why corrosion causes parts to be consumed, but the main reason is that the substances generated from the parts due to corrosion become unintentional impurities for the semiconductor and adversely affect the characteristics of the semiconductor to be processed. .

  For these reasons, the metal pipe extending from the outside of the furnace into the furnace needs to be changed to a pipe made of a material suitable for the in-furnace environment such as quartz glass in the furnace. Specifically, it is necessary to connect a metal pipe and a pipe made of a material such as quartz glass.

  Conventionally, the connection between the metal pipe and the quartz pipe is joined by brazing using an intermediate material such as Kovar glass or Kovar metal. However, it is more advantageous in terms of management to connect the quartz glass pipe and the metal pipe to the joint connection, and a new method of joint connection is desired.

  Next, the connection between the glass pipes will be described. Hereinafter, description will be made assuming that the piping in the furnace is made of quartz glass.

  There are many parts such as a raw material boat, a diffusion device called a diffuser, and a raw material blowing nozzle in the furnace, depending on the type of the reaction furnace. Welding can also be used as a method of connecting quartz glass piping to such contents, but in this case, the contents in the furnace become large and cannot be disassembled into individual parts after assembly. It becomes impossible to manage each. In order to increase the degree of freedom in disassembling and assembling the contents in the furnace, it is desirable to connect the piping to a joint connection, but there is no standard for joints that can be used in a high temperature environment or an environment with corrosive gas.

  For example, the common taper joint (JIS R3646), which is an existing standard, is not suitable for use inside a semiconductor manufacturing apparatus that pursues high quality because it is not a connection method that guarantees leakage at the connection. In a common taper joint, grease may be applied to improve hermeticity, but the grease cannot be used in a furnace of a semiconductor manufacturing apparatus which is a high temperature environment and dislikes impurities. Further, the necessity of a space in the longitudinal direction for inserting and removing the joint may be an obstacle to assembling the contents member. In addition, when there is a pulling force in the longitudinal direction of the pipe, there is a concern that the connecting portion may come off.

  The joint defined in the glass chemical plant component (JIS R3802) uses a flange and is not suitable for use in a furnace of a narrow semiconductor manufacturing apparatus. Moreover, the nominal diameter of the pipe defined in the standard is 15 mm or more, and does not correspond to a pipe diameter such as 1/4 inch (diameter 6.35 mm) which is usually used. Moreover, although it is necessary to use non-heat-resistant materials such as packing, insert, and clamp as the configuration of the connecting portion, it is obvious that these cannot be used in an environment where high temperature and corrosive gas exists.

  Under normal circumstances, the ISO standard clamp joint (ISO 2861-1) may be used to connect the glass tube. However, since the elastomer O-ring is used, it may be used in a high temperature environment. Can not.

  As described above, in glass pipes, particularly quartz glass pipes, there is no standard for joints that can be used in a furnace of an actual semiconductor manufacturing apparatus, and there is no recommended connection method. For this reason, in practice, the connection of the pipe is mostly made by welding.

  An object of the present invention is to provide a joint technique which is a method for connecting glass pipes, particularly quartz glass pipes, which can be used in a special environment such as in a furnace of a semiconductor manufacturing apparatus. Specifically, the joint type is a face seal pipe joint, the seal surface of the face seal pipe joint is a flat surface with an extremely high degree of flatness more than optically bonded, and the joint surface is fastened with screw means coaxial with the pipe By doing so, a joint system capable of realizing high airtightness is provided. In addition, since the sealing surface of the connecting end is a flat surface with extremely high flatness, it also provides a secondary effect that the sealing surfaces of the connecting end can be bonded together by heating the joint after connecting the joint. can do. Adhesion by heating is a relatively new technique in which flat surfaces having a degree of flatness higher than that for optical adhesion are bonded together by applying appropriate pressure and then heated to bond them.

  The above-mentioned adhesion by heating is very effective when it is desired to integrate the assembled pipes as one component without disassembling. In addition to using heating by flame or heating by high frequency, the sealing surface of the connection end of the pipe can be bonded using the high temperature in the semiconductor manufacturing apparatus furnace.

  Such a method, that is, connecting pipes with joints and then bonding the pipes by applying heat to the joints, such as the production of vacuum tubes such as photomultiplier tubes and the production of glass parts to be introduced into the vacuum, etc. Applications can be expected in a wide range of fields. This method is a completely new method that has not existed before.

  Conversely, when it is not desired to bond the bonding surfaces by heating, a material that does not bond even when heated may be selected as the gasket material. Of course, it is good also as a surface which gives a surface treatment to the sealing surface of a connection end part, and does not adhere | attach.

  Connecting a glass pipe joint to a face seal joint is also convenient for connection to an existing metal pipe face seal joint. In general, the connection end of the face seal joint of an existing metal pipe is not flat, but the gasket inserted between the seal face of the face seal pipe joint of the metal pipe and the seal face of the glass pipe joint of the present invention is deformed. Thus, it is possible to maintain airtightness by adhering to both sealing surfaces. For example, when connecting joints to face seal joints of metal pipes that use metal gaskets, joints with compatible seal diameters, screw connection means, and metal gaskets with sufficient flatness are inserted. What is necessary is just composition.

  Conventionally, since glass is hard and brittle and difficult to machine, it is difficult to process screw means, and a plane having an extremely high flatness of at least a degree of optical adhesion, that is, a flatness of about λ / 5 or more. Since these processes are extremely advanced techniques, and these processes require a large number of processing steps and costs, no joint technique similar to that of the present invention has been devised or implemented. However, in recent years, it has become possible to realize the pipe joint of the present invention by improving the glass surface polishing technology and making it possible to create screw parts by improving the glass machining technology.

The following techniques (1) to (4) are related to conventional glass pipe fittings.
(1) Common taper joint for glassware for scientific analysis (JIS R3646)
(2) Common spherical slip joint for glassware for chemical analysis (JIS R3651)
(3) Joints specified for glass chemical plant components (JIS R3802) (4) Clamp joints (ISO 2861-1)

Among the pipe joints of metal pipes, the following pipe joints (5) are likely to be required to be connected to glass pipes, particularly quartz pipes.
(5) VCR joints (US Pat. No. 6,318,766) which are face seal pipe joints provided by Swagelok

  The characteristics of each joint are described below.

(1) Common taper joint for glassware for scientific analysis (JIS R3646)
Connect the pipe by fitting the female taper and the male taper. The surface roughness of the Taber portion is 1 μm or less. According to this standard, leakage of 1.33 kPa or less is allowed for 5 minutes under a differential pressure of 50.77 kPa without grease. Grease needs to be applied to maintain a higher vacuum.

(2) Common spherical slip joint for glassware for chemical analysis (JIS R3651)
The shape of the rubbing is a spherical rubbing joint. Leaks that are at least as good as common taper joints are allowed.

(3) A joint glass standard for glass chemical plant components (JIS R3802), and borosilicate glass is to be used. For the connection, a gasket is sandwiched between spherical or flat connection ends, an insert is inserted, and the gasket is fixed with a packing flange.

(4) Clamp joint (ISO 2861-1)
An elastomeric O-ring is used, sandwiched between the flange surfaces, and the flange is fastened with a clamp. Originally, it is widely used for the connection of metal pipes, but it can also be applied to glass pipes by using glass as the material while keeping the flange in a standard shape. The clamp in this case is often a plastic chain clamp so that the glass does not crack.

(5) VCR joints (US Pat. No. 6,318,766) which are face seal pipe joints provided by Swagelok
The VCR joint is a face-sealed pipe joint that can use a metal gasket as a gasket, and is a joint that has high purity and does not leak from ultra-high vacuum to positive pressure. The material is stainless steel SUS316. The gasket can be selected from nickel, stainless steel and the like. Tighten the gasket at the connection end (seal surface) to keep it airtight.
FIG. 4 shows a typical configuration of the VCR joint. The upper half of the figure shows a cross-sectional view, and the lower half shows the appearance. FIG. 4 (a) shows the configuration of the parts before joint connection, and FIG. 4 (b) shows the state of joint connection.

References

(1) Common taper joint for glassware for scientific analysis (JIS R3646)
(2) Common spherical slip joint for glassware for chemical analysis (JIS R3651)
(3) Glass chemical plant components (JIS R3802)
(4) Clamp joint (ISO 2861-1)
(5) (US Patent US 6318766)

The conventional piping joint technology has the following problems (1) to (3).
(1) In joints that use gaskets, inserts, O-rings, etc., their materials are rubber and plastic, etc., which have poor heat resistance, and parts such as clamps and packing flanges are made of metal, so they have poor corrosion resistance. It cannot be used in a furnace of a semiconductor manufacturing apparatus in a high temperature environment and a corrosive gas atmosphere.
(2) A common taper joint that does not use an O-ring or gasket does not have sufficient airtightness. In particular, it does not have airtightness enough to cope with high vacuum.
(3) Connection with existing face seal joint for metal piping is not compatible.

  Means for solving the problems will be described.

  In order to be able to use in a high temperature environment, it is only necessary to remove rubber and plastic gaskets and O-rings from the joint and prepare a joint structure made of glass for all materials.

  In order to obtain airtightness that can be applied up to high vacuum, the joint structure is a face seal pipe joint structure that seals the end face of the pipe together, and the sealing surface (2) is flat enough to optically bond. What is necessary is just to use it as a joining surface as a plane which has a degree. In order to perform optical bonding, the flatness of the sealing surface (2) may be λ / 5 or more, preferably λ / 10. Here, the wavelength λ of the light is 633 nm.

  Hereinafter, the wavelength λ of light is 633 nm, and the flatness is a value evaluated under this wavelength λ. The flatness is evaluated by light wave interference caused by an optical flat. The flatness may be expressed as flatness, surface accuracy, flatness, etc.

  Optical bonding is a phenomenon in which when the surfaces of planes close to the ideal plane are brought together, the gap becomes infinitely narrow and the surfaces do not peel off. Although it is difficult to quantitatively express the flatness at which the optical adhesion phenomenon occurs, it is known that optical adhesion occurs at a flatness of about λ / 5 or more.

  Quartz glass may be selected as a joint material that can be used in a high temperature environment and a corrosive atmosphere such as in a reaction apparatus of a semiconductor manufacturing apparatus. If quartz glass is not suitable for the environment in which it is used, other materials such as dense ceramics having excellent corrosion resistance and heat resistance may be selected.

  In order to eliminate a very small gap between the optically bonded surfaces, the surfaces may be pressed with an appropriate force. Even when optically bonded, sufficient airtightness can be maintained, and only a very small gap remains between the sealing surfaces. However, the airtightness can be further improved by pressing the surfaces together.

  As means for abutting the seal surfaces, a joining means using screws may be used. The screw means used for the joining means using screws may be male screw means (4) and female screw means (5) arranged coaxially with the pipe. Glass screw means can be manufactured by recent improvements in glass machining technology.

In order to prevent loosening of the screw means made of glass, the surface of the screw may be grained. In order to prevent loosening, between the screw means and the contact portion between the screw means and the screw means provided in the pipe for transmitting the tightening force to the connection end of the pipe, that is, between the screw means and the ground (3). In addition, a glass spring may be inserted.
Since the sealing surface has extremely high flatness, the butt pressure can be set to a small value that does not damage the screw means made of glass.

  A gasket (8) may be used. In this case, the flatness of the sealing surface (9) of the gasket should be the same flatness as the sealing surface of the joint body, that is, the flatness more than the optical adhesion. Good. Specifically, the flatness should be λ / 5 or more, and desirably the flatness should be λ / 10 or more.

  When it is desired to bond the seal surfaces after connecting the joints and integrate them as a permanent pipe, heat may be applied to the joint surfaces of the seal surfaces. The joining surfaces can be bonded by appropriately setting the pressure and heating temperature of the butt surfaces between the sealing surfaces and the processing time.

  In order to facilitate adhesion, an intermediate material for adhesion may be used for the gasket. When pipes of different materials are connected, the gasket material may be selected in consideration of the thermal expansion coefficient of each material. Specifically, Kovar glass or Kovar metal may be selected as the gasket material.

  On the other hand, if it is not desired to bond even if heat is applied, a material that does not adhere to the joint material even if heat below the operating temperature is applied may be used as the gasket. For example, ceramics that are stable and dense at high temperatures may be selected as the gasket material. Specifically, silicon carbide, boron carbide, silicon nitride, carbon nitride, or the like may be selected as the gasket material.

  When connecting to a general face seal joint of metal piping, the joint configuration is to replace the diameter of the seal surface, replace the connection means by screws, and insert a metal gasket with sufficient flatness. do it.

  The present invention has the following effects.

(1) A joint and piping system in which all materials are glass can be configured.
That is, it is possible to construct a joint made of only glass without using organic parts such as rubber and plastic. In particular, by using high-purity quartz glass as the material, it can be used as a high-quality piping system in the semiconductor-related field. Specifically, a joint that can be used in a high-temperature environment up to about 1000 ° C. and a corrosive gas atmosphere can be provided. Even in the case of using a gasket, the material of the gasket can be glass or ceramics, so that the usable temperature can be higher than that of a conventional joint.

(3) A joint having extremely high airtightness can be provided.
Since the sealing surfaces are joined with no physical gaps or are bonded by applying heat, it is possible to connect joints with extremely high airtightness. If bonding is performed by applying heat after appropriately connecting the joints, permanent piping can be manufactured while maintaining high airtightness.

(2) It is possible to provide a glass pipe joint that is extremely easy to assemble pipes.
First, the fact that the joint connection is possible itself improves the working efficiency of the glass piping as never before. Furthermore, since the joint can be bonded by heating after connecting the joint, welding can be omitted from the pipe connecting work. This suggests that it is possible to assemble complex piping, which was difficult with welding, and it can be expected that the degree of freedom in pipe manufacturing will increase. Since the screw means coaxial with the pipe is used as a means for connection, the joint portion is compact and does not require an excessive space for assembly. Moreover, since it is not the connection method by insertion, it is not necessary to move the pipe in the longitudinal direction of the pipe at the time of connection, and workability is improved from the viewpoint of work space.

(3) A glass pipe joint that can be connected to a face seal joint of an existing metal pipe can be provided.
Not only is it possible to connect joints between glass pipes, but it is also possible to design joints that can be connected to face seal joints of existing metal pipes. This increases the freedom of piping components.
When a joint that requires an O-ring or the like is used to connect a metal pipe and a glass pipe as in the prior art, the use limit of the connection portion is at most about 100 ° C. due to the heat resistance problem of the O-ring. On the other hand, if the material of the existing metal pipe joint is stainless steel SUS316 and the gasket material is nickel or stainless steel SUS316, it can be used up to about 400 ° C, so the temperature at the limit of use becomes high and the degree of freedom in pipe design. Increase.

(5) A new pipe joining technique and adhesion technique can be provided.
All materials made of glass, compact and highly airtight joints are a new technology that has never been seen before. Similarly, a technique capable of applying heat to bond the pipes after the pipes are connected by the joints is an unprecedented innovation. These innovative technologies can be expected to provide new uses and applications of glass piping in the field of using glass piping, especially quartz glass piping. In particular, it is a great advantage that it is possible to test by temporarily connecting a joint before making the connection of the pipe permanent. For example, it can be easily imagined that it is advantageous in manufacturing a vacuum tube such as a photomultiplier tube.

  By combining these effects, the present invention can greatly contribute to the development of the industrial field using glass piping, particularly quartz glass piping. In the future, it is expected that it will be possible to construct joint components that can connect pipes of various materials by applying not only to glass pipes but also pipes made of metal or ceramics.

  An embodiment of the present invention will be described.

  Embodiments [Embodiment 1] to [Embodiment 5] are shown according to the order of claims. The glass material was quartz glass.

[Embodiment 1]
As Embodiment 1, it is possible to connect quartz glass pipes, and in addition, an example of a joint that can be connected to a face seal joint of an existing metal pipe is shown, and an example of connection between the quartz glass pipe joints is shown. Show.

  As a face seal joint for existing metal pipes, a VCR joint provided by Swagelok Corporation, which is a joint widely used in business, is a joint that is compatible with high purity and from positive pressure to high vacuum. Selected as an example. The size of the joint is for 1/4 inch piping.

FIG. 1 shows a quartz glass pipe joint of the first embodiment. The upper half of the figure shows a cross-sectional view, and the lower half shows the appearance. Fig.1 (a) shows the structure of the components before joint connection, FIG.1 (b) has shown the state connected by the joint.
The diameter of the quartz glass pipe (1) was ¼ inch (6.35 mm). A flat sealing surface (2) was provided at the end of the quartz glass pipe (1), and the flatness was λ / 10. Here, the wavelength λ of the light is 633 nm. A step for transmitting the tightening force of the screw means was provided on the sealing surface (2) of the connecting end portion to form a ground (3) as a tightening portion.

  In order to make the sealing surface of the connection end of the pipe tightly contact and connect, a screw means is provided on the coaxial line of the pipe. Specifically, male screw means (4) and female screw means (5) were provided coaxially with the pipe. The six screw surfaces were flat so that they could be tightened with a wrench. Although not shown in the figure, the screw means has a hole for confirming hermeticity in a helium leak test. The screw means is a screw specification compatible with the screw means of the VCR joint. Specifically, the size was 9 / 16-18UNF with a unified fine screw. The surface of the screw parts (6) and (7) was subjected to graining so that the male screw means (4) and the female screw means (5) made of quartz glass did not slip and loosen. A quartz spring for preventing slipping and loosening may be inserted between the male screw means (4) or the female screw means (5) and the ground (3).

  The tightening pressure varies depending on the material of the joint. However, considering the elasticity of the joint material, the tightening pressure may be tightened using as a guide the pressure that is the amount of deformation at which the sealing surfaces of the connecting end portions are in close contact with each other. For example, when the present invention is applied to a quartz glass material, a sufficient airtightness can be maintained with a tightening pressure of 0.5 MPa. The torque for tightening the screw may be managed with a torque wrench.

[Test Results of Embodiment 1]
Quartz glass joints were connected to each other, and an air tightness test and a helium leak test were conducted using a helium leak tester. One quartz tube of the joint was sealed at the end. The other end of the pipe was connected to a test port of the helium leak tester via an UltraTorr joint (manufactured by Swagelok), which is a joint using an O-ring, in order to connect to the helium leak tester.

As a result of the helium leak test, the leak rate was 5 × 10 ⁻⁷ (Pa · 1 / s) or less. Since this value is the background value of the helium leak tester used, it was substantially a detection limit, and there was no leak from the joint connection. There were no cracks at the end of the connection or screw.

Instead of connecting the connecting end directly, a gasket (8) may be inserted. FIG. 2 shows a configuration when a gasket (8) is inserted into the configuration of the quartz glass pipe joint of the first embodiment. The upper half of the figure shows a cross-sectional view, and the lower half shows the appearance. FIG. 2 (a) shows the configuration of the parts before the joint connection, and FIG. 2 (b) shows the state of the joint connection.
The tightening pressure varies depending on the material of the joint, but as in the case of directly connecting the sealing surface of the connection end, considering the elasticity of the joint material, the pressure that is the amount of deformation at which the connection end is in close contact is used as a guide. Tighten.
When the material of the gasket is the same as the material of the joint, no special function is added, but an additional function can be given by selecting the material according to the purpose as in the third and fourth embodiments.

[Embodiment 2]
As the second embodiment, an example in which the quartz glass pipe joints of the first embodiment are connected to each other by applying heat is shown.

  The joint of the embodiment 1 connected to the joint was heated at 1200 ° C. for 1 hour to be bonded.

[Test Results of Embodiment 2]
The screw means of the joint was loosened, and adhesion between the sealing surfaces of the connection end portions was confirmed. A helium leak test similar to that of Embodiment 1 was performed to confirm that there was no leak.

  Instead of directly bonding the connection end, a gasket (8) may be inserted and bonded. When the gasket is made of the same material as that of the joint, no special function is added, but an additional function can be given by selecting the material according to the purpose as in the third and fourth embodiments.

[Embodiment 3]
As a third embodiment, an example in which a gasket made of an intermediate material is inserted and bonded by applying heat in connection between the quartz glass pipe joints of the first embodiment will be described.
FIG. 2 shows a configuration for performing bonding by inserting a gasket in the third embodiment, that is, a quartz glass pipe joint. The upper half of the figure shows a cross-sectional view, and the lower half shows the appearance. FIG. 2 (a) shows the configuration of the parts before the joint connection, and FIG. 2 (b) shows the state of the joint connection.

  In order to facilitate bonding by heat, an intermediate material for bonding may be used for the gasket. The use of an intermediate gasket is particularly effective when bonding pipes of different materials having different coefficients of thermal expansion. Examples of the intermediate material include kovar glass and kovar metal. Depending on the material of the pipe joint, the heating temperature for bonding may be lowered by using an intermediate gasket. Further, when different types of material pipes are bonded, it is possible to select a material that acts as a cushioning material that relaxes the difference in thermal expansion coefficient of each material as a gasket. Furthermore, adhesion can be facilitated by evaporating a material to be a binder on the surface of the gasket.

  Kovar glass was selected as the material for the gasket (8), and both surfaces of the sealing surface of the gasket (8) were subjected to optical polishing with a flatness of λ / 10. Aluminum was vapor-deposited as a binder on both surfaces of the gasket (8). The gasket (8) was inserted into the joint, and the joint was connected by tightening with the male screw means (4) and the female screw means (5) with a tightening pressure of 0.5 MPa. After that, it was heated in an oven at 800 ° C. for 1 hour for adhesion.

As a heating means for bonding, various methods such as heating with a flame, high-frequency heating, and use of atmospheric temperature in the furnace can be used.
Of course, the screw means may be removed after bonding.

[Test Results of Embodiment 3]
The screw means of the joint was loosened, and adhesion between the sealing surfaces (2) at the connection end was confirmed. A helium leak test similar to that of Embodiment 1 was performed to confirm that there was no leak.

  In the third embodiment, the adhesion between the quartz glass pipes is shown. However, the metal pipe and the glass pipe such as quartz glass are formed by using the metal pipe as a joint having the shape of the present invention and using Kovar metal and Kovar glass as a gasket. Those skilled in the art will readily understand that they can be connected by bonding.

[Embodiment 4]
Embodiment 4 shows an example of connection of joints when a gasket made of a material that prevents adhesion is inserted in the connection between quartz glass tube joints of Embodiment 1.
FIG. 2 shows the configuration of the fourth embodiment, that is, a case where a gasket that does not adhere even when heat is applied to a quartz glass pipe joint is inserted. The third embodiment is different from the third embodiment only in that the gasket (8) is made of a material that does not adhere even when heat is applied. The upper half of the figure shows a cross-sectional view, and the lower half shows the appearance. FIG. 2 (a) shows the configuration of the parts before the joint connection, and FIG. 2 (b) shows the state of the joint connection.

  In order to prevent the connecting portion from adhering when heat is applied, a gasket material that does not adhere to the joint material due to heat may be selected. Examples of the material for the gasket include hard and dense ceramics such as silicon nitride, carbon nitride, and boron carbide that are stable even at high temperatures.

  In the example, a sintered material of carbon nitride (SiC) was selected as the material of the gasket, and optical polishing with a flatness of λ / 10 was performed on both surfaces of the sealing surface (9) of the gasket (8).

[Test Results of Embodiment 4]
A gasket (8) was inserted into the joint, and the screw means was tightened with a tightening pressure of 0.5 MPa. A helium leak test was conducted after connecting the joints to confirm that there was no leak. Subsequently, the joint was subjected to heat treatment at 1200 degrees for 1 hour in a furnace. After cooling to room temperature, a helium leak test was performed to confirm that there was no leak. Thereafter, the screw means was loosened, and the state of the connecting portion was confirmed. As a result, it was confirmed that adhesion between the sealing surface (2) at the connection end and the gasket (8) was not observed.

[Embodiment 5]
As Embodiment 5, the example of the connection of the quartz glass pipe joint of Embodiment 1 and the existing metal piping joint is shown.
FIG. 3 shows a connection configuration of the quartz glass pipe joint of Embodiment 5 and an existing metal pipe joint. The upper half of the figure shows a cross-sectional view, and the lower half shows the appearance. FIG. 3 (a) shows the structure of the parts before the joint connection, and FIG. 3 (b) shows the state of the joint connection.

  As an existing metal pipe joint, a VCR joint provided by Swagelok was selected as an example.

First, a gasket was prepared. The material of the gasket (8 ′) was nickel. In order to improve the flatness of the sealing surfaces (9 ′) on both sides of the gasket (8 ′) and to improve the accuracy of the surface roughness, mechanical polishing was performed, followed by electrolytic polishing. As the screw means for connection, a male male screw means (4 ′) and a female screw means (5 ′) prepared as screw means for a Swagelok VCR joint were used as they were. This is because the screw means made of metal is more advantageous than the screw means made of quartz glass in order to sufficiently tighten the metal gasket. Since the temperature of the use environment of the joint is limited by the usable temperature of the gasket, there is no problem in using metal screw means as long as the temperature is equal to or lower than this limit temperature.
A gasket was inserted between the metal pipe joint and the quartz glass pipe joint, and tightened by screw means. The tightening was performed by tightening the screw means by hand tightening according to the predetermined tightening of the VCR joint, and then performing 1/8 turn tightening with a wrench.

[Test Results of Embodiment 5]
As a result of the helium leak test, the leak rate was 5 × 10 ⁻⁷ (Pa · 1 / s) or less. Since this value is the background value of the helium leak tester used, it was substantially a detection limit, and there was no leak from the joint connection. The quartz glass pipe joint was not damaged by tightening. In addition, there was no trace of scratches on the sealing surface on the quartz glass side.

  It should be understood by those skilled in the art that these embodiments are representative examples, various modifications are possible, and such modifications are also included in the scope of the present invention. In the embodiment, the joint is made of quartz glass, but other glass materials are also included in the scope of the present invention. Similarly, the joint is made of ceramics or metal in the scope of the present invention. This will be understood by those skilled in the art.

  2 is a configuration of a joint according to the first embodiment.   It is the structure of the joint concerning Embodiment 2 and Embodiment 3. FIG.   6 is a configuration of a joint according to a fourth embodiment.   It is the structure of the existing metal face seal fitting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piping 2 Seal surface 3 Ground 4 Male screw means 5 Female screw means 6 Screw part of male screw means 7 Screw part of female screw means 8 Gasket 9 Seal surface of gasket 1 'Metal piping 2' Existing metal surface seal fitting 3 'Existing metal face seal fitting gland 4' Existing metal face seal fitting male screw means 5 'Existing metal face seal fitting female screw means 6' Existing metal face Thread part of seal fitting 7 'Thread part of existing metal face seal fitting 8' Gasket of existing metal face seal fitting 9 'Seal face of gasket of existing metal face sealing fitting

Claims (9)

  The end face of the pipe is a seal face (2), and the seal face (2) is joined to join the same or different material pipe, and the seal face (2) is flat. The surface seal pipe joint is characterized in that the flatness of the seal surface (2) is equal to or greater than the degree of optical adhesion when bonded to a plane having the same flatness or more.   2. The face seal joint according to claim 1, wherein the flatness of the seal surface (2) is a plane of λ / 5 or more, preferably a plane of λ / 10 or more in the flatness measurement with light having a wavelength λ of 633 nm. A face seal pipe joint characterized by being.   3. The face seal pipe joint according to claim 1, wherein the material of at least one pipe joint is quartz glass.   4. The face seal pipe joint according to claim 1, wherein fastening by a male screw means (4) and a female screw means (5) coaxial with the pipe is used as a joining means of the seal surface (2). Face seal fitting.   The face-sealed pipe joint according to claims 1 to 4, wherein the gasket (8) is used, the gasket sealing surface (9) is flat, and the flatness of the gasket sealing surface (9) is the same flatness. A face-sealed pipe joint characterized by using a gasket (8) that is more than optically bonded when bonded face-to-face with the above plane.   5. The face seal fitting according to claim 1, wherein the flatness of the seal surface (9) of the gasket according to claim 5 is a plane of λ / 5 or more in the flatness measurement using light having a wavelength λ of 633 nm. A face-sealed pipe joint characterized by using a gasket (8) that is preferably a plane of λ / 10 or more.   7. The joint technology according to claim 1, wherein the joint portion is bonded by applying heat to the joint portion after joining the seal surface (2).   8. Joining technique according to claim 7, characterized in that an intermediate material for joining is used as the gasket (8).   The face seal joint according to any one of claims 1 to 6, wherein the gasket (8) is made of a material that does not cause the seal surface (2) and the seal surface (9) of the gasket to adhere to each other by heating. Face seal fitting.

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