JP2009030644A - Seal connecting construction, structure, and covering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal connecting construction, its structure and a covering method, having a corrosion resistance and heat resistance, offering a long period of service, and efficiently preventing a high-temperature corrosive fluid from leaking out of the internal flow passage R. <P>SOLUTION: The seal connecting construction 40 is provided between two members to be connected 1 and 2 constituting the internal flow passage R in which the high-temperature corrosive fluid flows. The construction 40 seals and connects together the two members 1 and 2 to be connected. The construction 40 is equipped with a sealing member body 11 arranged between the two members 1 and 2, a sealing member 10 made of metal having a corrosion resistant metal layer 12 covering the sealing member body 11 and contacting the corrosive fluid at high temperature, and a fastening part 20 to fasten the two members 1 and 2 to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a seal connection structure for sealing and connecting a container for holding a high-temperature, high-pressure liquid or gas, a pipe to be transferred, and the like, and particularly excellent for strong acid, its vapor, or corrosive gas. The present invention relates to a seal connection structure having corrosion resistance and heat resistance. The present invention also relates to a structure provided with such a seal connection structure, and a coating method for coating such a structure.

  Generally, a power plant, a chemical plant, etc. are comprised from the container which hold | maintains liquid and gas, and the piping which transfers these liquid and gas. These containers and pipes are connected by fastening connection parts such as flanges with bolts 21 or the like via seal members such as metal gaskets, rubber or resin O-rings.

  In general, when heat resistance is required, a metal gasket made of copper or stainless steel is used as the seal member. The seal member made of such a metal gasket is resistant to strong acids and corrosive gases at high temperatures. Is not necessarily enough. On the other hand, when corrosion resistance is required, a rubber seal member or a resin seal member made of a resin material such as Teflon (registered trademark) is used, but the heat resistance is limited to 300 ° C. at most. .

For example, a thermochemical IS process method hydrogen production system for producing a large amount of hydrogen and oxygen from a water raw material using nuclear heat of about 950 ° C. basically comprises the following three subsystems.
I ₂ + SO ₂ + 2H ₂ O = 2HI + H ₂ SO ₄ : Bunsen reaction (exothermic) to 100 ° C.
2HI = _{H 2} + I _2: hydrogen iodide decomposition reaction (endothermic) 400 ° C.
H ₂ SO ₄ = H ₂ O + SO ₂ + 1 / 2O ₂ : sulfuric acid decomposition reaction (endothermic) 800 ° C.

  Of these three subsystems, the hydrogen iodide decomposition reaction and the sulfuric acid decomposition reaction exchange heat with high-temperature helium gas supplied from a high-temperature gas furnace through a heat exchanger, to produce highly corrosive sulfuric acid or Decomposes hydrogen iodide.

  Since these reaction temperatures are carried out at a high temperature of 400 ° C. to 800 ° C. or higher, the above-described metal gasket is corroded in a short time by high-temperature sulfuric acid or hydrogen iodide, so that a rubber seal member or resin is used. The made sealing member is too hot to be applied.

  As a method for sealing such a high temperature corrosive fluid, there is a method proposed in Patent Document 1. As shown in FIG. 3, the invention described in Patent Document 1 has a predetermined diameter difference between the joined surface of one joined body (connection target member) 1 and the other joined body (connection target member) 2. The stepped portions 1t and 2t that mesh with each other are provided, and a seal ring 35 that has an opening 35a in the axial direction is attached to the space 31 formed between the stepped portions 1t and 2t that mesh with each other due to the difference in diameter. Yes.

  According to such a structure, even if a large difference in thermal expansion occurs between one joined body 1 and the other joined body 2, it can be absorbed by elastic deformation of the seal ring 35. That is, the tip 35b of the seal ring 35 can contact the stepped portions 1t and 2t of the one joined body 1 and the other joined body 2 to seal the fluid.

Further, since the difference in radial thermal expansion can be absorbed by the elastic deformation of the seal ring 35 itself, it is possible to suppress leakage due to a decrease in the seal surface pressure and a change in the contact state due to slippage of the seal contact surface.
JP 2006-317106 A

  Certainly, according to the invention described in Patent Document 1, in a combination of dissimilar materials having a large difference in thermal expansion coefficient between one joined body 1 and the other joined body 2, a seal connection structure that alleviates the difference in thermal expansion between them. It is effective as. However, it is indispensable to use a material that has excellent corrosion resistance and does not undergo plastic deformation even at high temperatures as a material for the seal connection structure, and it is difficult to find a material that meets such requirements.

  Further, the inner surfaces of one joined body 1 and the other joined body 2 are often coated with a corrosion resistant material such as glass or cerax, and such a corrosion resistant material is brittle and has low toughness. When there is a discontinuous portion such as 2t, stress concentration occurs in the corner portion, and there is a high possibility that cracks will occur in the coating layer made of a corrosion-resistant material.

  The present invention has been made in consideration of such points, has corrosion resistance and heat resistance, can be used for a long time, and efficiently leaks hot corrosive fluid from the internal flow path. It is an object of the present invention to provide a seal connection structure that can be prevented, a structure including the seal connection structure, and a coating method that covers the structure.

  As will be described later, the present inventors evaluated the corrosion behavior of various metal materials, ceramic materials, and glass materials in boiling concentrated sulfuric acid.

  As a result, it was found that metal materials other than gold, platinum, and silver were completely dissolved in a short time, and platinum and silver also showed a tendency to corrode, and only gold exhibited excellent corrosion resistance.

  Also, in ceramic materials, densely sintered silicon carbide showed excellent corrosion resistance. However, when such ceramic materials are also used as thin film coatings formed by CVD, pinhole-like defects are caused. It became clear that the thin film coating penetrated and was inferior in reliability.

Furthermore, as for glass materials, it has been revealed that quartz exhibits excellent corrosion resistance, and glass materials having a relatively large SiO ₂ content such as soda glass also exhibit excellent corrosion resistance. However, when such a glass material is also used as a thin film coating manufactured by a coating method such as PVD method or CVD method, it is penetrated by a pinhole-like defect and reliability is improved. It became clear that it was inferior.

  By the way, the seal member needs an appropriate elastic deformation with respect to a tightening pressure such as a bolt. In the above selected materials, gold has low strength at high temperature and extremely low elastic limit stress, and silicon carbide and glass have high temperature strength but hardly cause elastic deformation and break brittlely. Therefore, it is not suitable as a material for the seal member.

  On the other hand, iron-based alloys such as stainless steel and Ni-based alloys such as Inconel are remarkably inferior to the selected materials, but have been confirmed to exhibit good elastic deformation even at high temperatures exceeding 500 ° C.

  Therefore, a seal member that combines heat resistance and corrosion resistance at high temperatures is manufactured by using a metal material with excellent elastic deformability as the material of the seal member and providing a corrosion-resistant metal layer on the portion that contacts the corrosive fluid. can do.

  In view of the above, the present inventors have found a seal connection structure, a structure, and a coating method as described below.

The present invention is installed between one connection target member and the other connection target member forming an internal flow path through which a high-temperature corrosive fluid flows, and this one connection target member and the other connection target member are connected to each other. In the seal connection structure that seals and connects,
A metal sealing member that is disposed between one connection target member and the other connection target member, and has a seal member body and a corrosion-resistant metal layer that covers the seal member body and contacts a high-temperature corrosive fluid When,
A fastening portion that fastens one connection target member and the other connection target member;
It is the seal | sticker connection structure characterized by providing.

  With such a configuration, it is possible to obtain a seal connection structure that has corrosion resistance and heat resistance, can be used for a long time, and can efficiently prevent high-temperature corrosive fluid from leaking from the internal flow path. it can.

  The present invention is the seal connection structure characterized in that the corrosion-resistant metal layer of the metal seal member is made of gold.

  Thus, by using gold as the material of the corrosion-resistant metal layer of the metal seal member, the corrosion of the metal seal member by the corrosive fluid can be suppressed for a long period of time.

  In general, since gold has a lower hardness than the metal material used for the seal member body, the gap between the connection target member and the metal seal member can be efficiently filled. It is possible to efficiently prevent the hot corrosive fluid flowing through the internal flow path from leaking between the member and the metal seal member.

  The present invention is the seal connection structure, wherein the thickness of the corrosion-resistant metal layer of the metal seal member is 20 μm or more.

  In this way, by setting the thickness of the corrosion-resistant metal layer to 20 μm or more, even when defects such as pinholes or impurities are mixed or mixed in the corrosion-resistant metal layer, high-temperature corrosive fluid flows from the internal channel. It can be prevented that the metal seal member is reached through defects and impurities in the corrosion-resistant metal layer, and the metal seal member inferior in corrosion resistance is corroded.

  In addition, even if there is a foreign object or a processing flaw on the surface of the connection target member in contact with the corrosion-resistant metal layer or the surface of the metal seal member, fatal damage that penetrates from the surface to the back surface of the corrosion-resistant metal layer occurs. This can be prevented.

  The present invention is a seal connection structure in which a seal member body of a metal seal member is made of an iron-based, nickel-based, or cobalt-based alloy.

  The seal member body of the metal seal member is preferably made of a material that does not deteriorate or become brittle as a material over a long period of time and that can be elastically deformed moderately by tightening pressure. As a metal material suitable for such conditions, iron-based alloys such as stainless steel and iron-chromium alloys, nickel-based alloys such as Inconel and Hastelloy, and cobalt-based alloys are suitable.

  In addition, by using such a metal material as the seal member body of the metal seal member, it is possible to suppress a decrease in tightening stress due to high-temperature compression creep deformation of the seal member. Excellent seal performance can be maintained over a long time.

In the present invention, the metal seal member has a ring shape surrounding the internal flow path of one connection target member and the other connection target member,
Each of the surface which contacts one connection object member of a metal seal member, and the surface which contacts the other connection object member consists of flat form, It is a seal connection structure characterized by the above-mentioned.

  By using the metal seal member having such a shape, it is possible to prevent damage due to concentration of tightening stress or thermal stress on the surface of the seal member or the connection target member.

  Furthermore, the contact area of the contact surface between the metal seal member and the connection target member can be adjusted by changing the inner diameter and the outer diameter of the ring shape of the metal seal member. The tightening pressure can be optimized in accordance with the material of the steel member and the use conditions.

  The present invention is a seal connection structure characterized in that the longitudinal cross-sectional shape of the metal seal member is formed in an arc shape or a chamfered shape on the inner surface in contact with the corrosive fluid.

  By using the seal connection structure having such a shape, even when subjected to a temperature cycle accompanying start / stop, no thermal stress concentration occurs in the corrosion-resistant metal layer, and the corrosion-resistant metal layer is due to a difference in thermal expansion from the seal connection structure. Can be avoided.

The present invention, the fastening portion comprises a bolt that penetrates one connection target member and the other connection target member, and a nut that fits the bolt,
The seal connection structure is characterized in that a locking member is provided between the bolt and one connection target member and between the nut and the other connection target member.

  With such a configuration, even when the seal connection structure and the anticorrosion coating layer are compressively deformed, a predetermined tightening stress can be maintained, so that high temperature corrosive fluid flowing through the internal flow path can be prevented from leaking. Can be obtained.

One aspect of the present invention forms an internal flow path through which a hot corrosive fluid flows,
The other connection connecting member that is connected to one connection target member and forms an internal flow path through which a high-temperature corrosive fluid flows;
A seal connection structure that is installed between one connection target member and the other connection target member, and seals and connects the one connection target member and the other connection target member;
Seal connection structure
A metal sealing member that is disposed between one connection target member and the other connection target member, and has a seal member body and a corrosion-resistant metal layer that covers the seal member body and contacts a high-temperature corrosive fluid When,
A fastening portion that fastens one connection target member and the other connection target member;
It is a structure characterized by having.

  With such a configuration, it has corrosion resistance and heat resistance and can be used for a long period of time, and high temperature corrosive fluid can be efficiently prevented from leaking from the internal flow path.

  The present invention is a structure characterized in that one connection target member and the other connection target member have a corrosion-resistant coating layer made of a corrosion-resistant material at least in a portion in contact with the metal seal member.

  The corrosion-resistant metal layer that constitutes the surface of the metal seal member is made of a material such as gold, silver, or platinum, but these metals are electrochemically noble materials and are in contact with other metals. In this case, the metal in contact becomes an anode. Therefore, a local battery having a large potential difference is formed between the connection target member and the corrosion-resistant metal layer, and the connection target member undergoes corrosion at a very high rate. For this reason, it is possible to prevent the formation of a local battery having a large potential difference as described above by covering at least a portion of the surface of the connection target member that is in contact with the metal seal member with a corrosion-resistant material. The connection target member can be used stably over a long period of time.

  The present invention is a structure in which one connection target member and the other connection target member have a corrosion-resistant coating layer made of glass in a portion where the internal flow path is formed.

  When the connection target member is coated with a corrosion-resistant material made of metal to form a corrosion-resistant coated metal layer, the connection target member and the corrosion resistance are used unless the connection target member is covered with the same material used for the connection target member. A potential difference is generated between the coated metal layer and a local battery is formed, and there is a high possibility of accelerating the corrosion of the connection target member.

  Therefore, it is possible to completely prevent the formation of the local battery as described above by using glass that is excellent in corrosion resistance and insulating material as a material for covering the connection target member. It can be used stably for a long time.

  The present invention is a structure in which the glass used as a material for the corrosion-resistant coating layer is made of soda-based glass.

  As the glass used as the material for the corrosion-resistant coating layer, quartz glass is preferable from the viewpoint of corrosion resistance, but the softening and firing temperature of quartz glass is as high as 1000 ° C. or higher, and it is difficult to coat a metal connection target member. is there. On the other hand, soda-based glass has good corrosion resistance even in a high-temperature strong acid and has a softening / firing temperature of 500 to 800 ° C., so that it is suitable for coating even a metal connection target member.

  Therefore, as described above, by using soda glass as a material for covering the connection target member, the thermal stress generated when the connection target member is covered can be reduced, and the connection target member can be deformed. It is also possible to prevent alteration.

  In the present invention, at least one of the one connection target member and the other connection target member supports the metal seal member from the outside on the outer side opposite to the internal flow path side with respect to the metal seal member. It is a structure characterized by having a convex part or a stepped part.

  Since the metal seal member is always subjected to a tightening pressure, it is compressed and deformed, and tends to be deformed and expanded in the radial direction. For this reason, the metal seal member is provided with a convex portion or a stepped portion for supporting the metal seal member from the outside on the outer side opposite to the internal flow path side with respect to the metal seal member. Can be prevented from expanding and deforming outward, and the seal member can be positioned.

The present invention is a coating method for coating the surface of one connection target member and the other connection target member of the structure,
An application step of applying a soda glass-based powder to a portion that comes into contact with a corrosive fluid among the surfaces of one connection target member and the other connection target member;
A baking step of baking the applied soda glass-based powder,
By repeating the coating step and the firing step a plurality of times, a portion of the surface of one connection target member and the other connection target member that contacts the corrosive fluid is covered with a glass layer having a desired thickness. This is a method of covering the structure.

  By forming a glass layer using such a coating method to form a multilayer structure, even if a defect such as a pinhole occurs inside the glass layer that covers the surface of the connection target member, the generated defect is not detected in the glass layer. It is possible to prevent the connection target member from corroding without penetrating from the surface to the connection target member.

  According to the present invention, by using a metal seal member having a seal member body that performs a sealing function and a corrosion-resistant metal layer that performs a corrosion-resistant function and a heat-resistant function, it can be used for a long period of time with corrosion resistance and heat resistance. It is possible to obtain a seal connection structure that can efficiently prevent high-temperature corrosive fluid from leaking from the internal flow path, and a structure including the seal connection structure. Moreover, it can prevent that a connection object member corrodes by using the coating method which coat | covers the surface of a connection object member with the glass layer of a multilayer structure.

BEST MODE FOR CARRYING OUT THE INVENTION

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a structure and a seal connection structure according to the present invention will be described below with reference to the drawings. Here, FIG. 1 and FIG. 2 are diagrams showing an embodiment of the present invention. Here, FIG. 1 is a schematic longitudinal sectional view showing a structure provided with a seal connection structure according to the present embodiment.

  As shown in FIG. 1, the structure 50 is connected to one joined body (one connection target member) 1 that forms an internal flow path R through which a high-temperature corrosive fluid flows, and the one joined body 1. At the same time, it is installed between the other joined body (the other connection target member) 2 forming the internal flow path R through which the high-temperature corrosive fluid flows, and the one joined body 1 and the other joined body 2. A seal connection structure 40 that seals and connects the joined body 1 and the other joined body 2 to each other.

  Among these, as shown in FIG. 1, the seal connection structure 40 is disposed between one joined body 1 and the other joined body 2 and seals the one joined body 1 and the other joined body 2. The seal member 10 includes a fastening part 20 that connects one joined body 1 and the other joined body 2.

  Further, as shown in FIG. 1, the metal seal member 10 includes a seal member main body 11 disposed between one joined body 1 and the other joined body 2, and the seal member main body 11 so as to cover the high temperature. And a corrosion-resistant metal layer 12 in contact with the corrosive fluid.

  Moreover, as shown in FIG. 1, one joined body 1 and the other joined body 2 include a bolt 21 penetrating the flange portion 1a of one joined body 1 and the flange portion 2a of the other joined body 2, The nuts 22 that are engaged with the bolts 21 are connected to each other. As shown in FIG. 1, a loosening prevention member 24 such as a disc spring or a spring washer is provided between the bolt 21 and one joined body 1 and between the nut 22 and the other joined body 2. ing.

  In FIG. 1, the seal member main body 11 of the metal seal member 10 is made of an iron-based, nickel-based, or cobalt-based alloy having excellent heat resistance and elastic deformability.

  Further, as shown in FIG. 1, one joined body 1 and the other joined body 2 are made of a corrosion-resistant coating layer 5 made of glass in a portion that contacts the metal sealing member 10 and a portion that forms the internal flow path R. 6. The soda-based glass has good corrosion resistance even in a high-temperature strong acid, and the softening / baking temperature is 500 to 800 ° C. Therefore, the glass used as the material of the corrosion-resistant coating layers 5 and 6 is made of soda-based glass. It is preferable.

  Further, as shown in FIG. 1, the corrosion-resistant metal layer 12 covering the seal member main body 11 extends from a portion where the internal flow path R is formed to a portion where the metal seal member 10 contacts the joined bodies 1 and 2. . In addition, it is preferable that this corrosion-resistant metal layer 12 is comprised from gold | metal | money, such as gold foil and gold plating, for the reason mentioned later.

  As shown in FIG. 1, the metal seal member 10 has a ring shape surrounding the internal flow path R of one joined body 1 and the other joined body 2. Moreover, as shown in FIG. 1, each of the surface which contacts the one conjugate | zygote 1 of the metal sealing member 10 and the surface which contacts the other conjugate | zygote 2 has flat plate shape.

  Moreover, as shown in FIG. 1, the longitudinal cross-sectional shape (shape seen by cutting along the internal flow path R) of the corrosion-resistant metal layer 12 has an arc-shaped inner surface in contact with the corrosive fluid. The longitudinal cross-sectional shape of the corrosion-resistant metal layer 12 is not limited to such an arc shape, and may be any shape as long as the corner portion is chamfered and has no corners.

  As shown in FIG. 1, each of the one joined body 1 and the other joined body 2 is disposed on the outer side opposite to the inner flow path R side with respect to the metal seal member 10, and the metal seal It has the projection parts 7 and 8 which support the member 10 from the outside. The protrusions 7 and 8 are arranged in a circular shape so as to surround the internal flow path R.

  Note that, in the above description, the embodiment in which each of the one joined body 1 and the other joined body 2 has the protrusions 7 and 8 is used. Only one of the bodies 2 may have the protrusions 7 and 8.

  Moreover, the one joined body 1 and the other joined body 2 may have a stepped portion that supports the metal sealing member 10 from the outside instead of the protruding portions 7 and 8 as shown in FIG. .

  Next, the function and effect of the present embodiment having such a configuration will be described.

  First, general effects of the structure 50 and the seal connection structure 40 according to the present embodiment shown in FIG. 1 will be described.

  In FIG. 1, a high-temperature corrosive fluid flows through the internal flow path R formed by the joined bodies 1 and 2.

  Here, as shown in FIG. 1, between one joined body 1 and the other joined body 2, a seal member main body 11 and a corrosion resistance that covers the seal member main body 11 and comes into contact with a hot corrosive fluid. A metal sealing member 10 having a metal layer 12 is arranged to seal a gap between one joined body 1 and the other joined body 2.

  For this reason, it is possible to prevent the corrosive fluid from leaking outside from the internal flow path R formed by the joined bodies 1 and 2.

  In FIG. 1, a metal material excellent in elastic deformability is used as the material of the seal member main body 11, and a metal material excellent in corrosion resistance is used as the material of the corrosion-resistant metal layer 12 on the surface in contact with the high temperature corrosive fluid.

  In this regard, in FIG. 1, the flange portions 1 a and 2 a of the joined bodies 1 and 2 are fastened by bolts 21 and nuts 22, so that the seal member body 11 of the metal seal member 10 can be appropriately compressed and deformed. And can perform a sealing function. Moreover, in FIG. 1, the seal member main body 11 can suppress corrosion by the corrosion-resistant metal layer 12 provided on the surface of the metal seal member 10.

  That is, the seal member main body 11 that performs a sealing function and the corrosion-resistant metal layer 12 that performs a corrosion-resistant function and a heat-resistant function have separate structures, and materials suitable for each of the seal function, the corrosion-resistant function, and the heat-resistant function are used. Therefore, it can be used for a long period of time with corrosion resistance and heat resistance, and it is possible to efficiently prevent leakage of high temperature corrosive fluid from the internal flow path.

  The metal seal member 10 is not eroded even when exposed to a high temperature corrosive fluid for a long time, and therefore, the high temperature corrosive fluid is prevented from leaking from the internal flow path R over a long period of time and sealed. The function can be maintained.

  Moreover, as shown in FIG. 1, since each of the surface which contacts the one conjugate | zygote 1 of the metal sealing member 10 and the surface which contacts the other conjugate | zygote 2 consists of flat form, it is the conjugate | zygote 1,2. The glass-based anticorrosion coating layers 5 and 6 covering the film have a structure in which stress concentration does not occur.

  Further, as shown in FIG. 1, the longitudinal cross-sectional shape of the corrosion-resistant metal layer 12 (the shape seen by cutting along the internal flow path R) is such that the inner surface in contact with the corrosive fluid has an arc shape. Further, it is possible to prevent the corrosion-resistant metal layer 12 covering the surface of the seal member main body 11 from being damaged by the thermal stress accompanying the start / stop.

  Further, as shown in FIG. 1, each of the one joined body 1 and the other joined body 2 is arranged on the outer side opposite to the inner flow path R side with respect to the metal seal member 10, and the metal seal Since the protrusions 7 and 8 that support the member 10 from the outside are provided, the metallic seal member 10 can be prevented from being deformed outward by the tightening compression stress.

  Moreover, as shown in FIG. 1, since the locking member 24 is provided between the bolt 21 and the one joined body 1 and between the nut 22 and the other joined body 2, the metal is tightened by compressive stress. When the seal member 10 is creep-deformed, it is possible to prevent the corrosive fluid from leaking from the internal flow path R.

Hot corrosion test Next, the results of the test for high-temperature corrosion properties was performed in order to select the appropriate as material used for the corrosion resistant metal layer 12 (high-temperature corrosion test) will be described with reference to FIG.

<Material of corrosion-resistant metal layer 12>
In this high-temperature corrosion test, a 3 × 20 × 0.5-2.0 mm square bar-shaped test piece is immersed in boiling sulfuric acid at about 310 ° C. for a certain period of time, and then the weight is measured. The corrosion depth was calculated.

  The test piece materials are zirconium (A in FIG. 2), hastelloy (B in FIG. 2), tantalum (C in FIG. 2), stainless steel (D in FIG. 2), soda glass (E in FIG. 2), quartz. Glass (F in FIG. 2), silicon carbide (G in FIG. 2), and gold (H in FIG. 2) were used.

  From the results of the high temperature corrosion test shown in FIG. 2, zirconium (A in FIG. 2), Hastelloy (B in FIG. 2), tantalum (C in FIG. 2), and stainless steel (FIG. 2), which are usually used as corrosion-resistant metal materials. D) shows a very large amount of corrosion, and it can be seen that it cannot be applied alone as the corrosion-resistant metal layer 12 of the metal seal member 10.

  However, zirconium (A in FIG. 2), Hastelloy (B in FIG. 2), tantalum (C in FIG. 2), and stainless steel (D in FIG. 2) are elastically deformed to a stress of 200 MPa or more at a temperature of 500 ° C. Therefore, it can be said that it is an excellent seal material in terms other than the corrosion resistance.

  On the other hand, the amount of corrosion of soda glass (E in FIG. 2), quartz glass (F in FIG. 2), silicon carbide (G in FIG. 2), and gold (H in FIG. 2) is extremely small, and against high-temperature strong acids It can be seen that it exhibits excellent corrosion resistance.

  However, since soda glass (E in FIG. 2), quartz glass (F in FIG. 2), and silicon carbide (G in FIG. 2) are brittle in material and have a small amount of elastic deformation, they are suitable as seal materials. Absent.

  On the other hand, gold (H in FIG. 2) exhibits large elastic deformation at low temperatures but has a low yield stress at high temperatures, so it is not suitable as a seal material, but it has corrosion resistance to protect the seal member. It can be said that the material of the metal layer 12 is suitable.

  Next, in order to investigate the characteristics of gold used as the material of the corrosion-resistant metal layer 12 in the above-described embodiment, a corrosion test for 100 hours in boiling sulfuric acid was similarly performed on a gold plating material and a gold thin plate material (solid material). It was.

  The test piece used was gold plated around a material having a diameter of 20 mm and a thickness of 3 mm. At that time, five samples having different gold plating thicknesses of 10 μm, 20 μm, 30 μm, and 50 μm were prepared, and a corrosion test for 100 hours was performed for each to evaluate the presence or absence of corrosion. For the gold solid material, a test piece having a diameter of 20 mm and a thickness of 0.2 mm was used.

  The results of the gold corrosion test are shown in Table 1 below. In the table, “○” indicates that no corrosion was observed, and “×” indicates that corrosion was observed.

  As shown in Table 1, it can be seen that the smaller the gold plating thickness, the higher the probability of corrosion. This is because the thinner the gold plating thickness, the higher the probability that pinholes and impurities formed in the gold plating layer exist through the thickness of the gold plating. From the results in Table 1, the gold plating thickness is It can be seen that the thickness is preferably 20 μm or more, and more preferably 50 μm or more. In addition, as shown in Table 1, it turns out that it is very useful also to use the gold | metal | money of a solid material.

<Material of corrosion-resistant coating layers 5 and 6>
Next, the results of studying materials used for the corrosion-resistant coating layers 5 and 6 that coat the joined bodies 1 and 2 will be described.

  It is preferable that the surfaces of the joined bodies 1 and 2 are coated with a material having corrosion resistance. In particular, a portion of the surfaces of the joined bodies 1 and 2 that is in contact with the metal seal member 10 is higher by the metal seal member 10. Since it is tightened by surface pressure, it is preferable to coat with a material having not only corrosion resistance but also strength that does not cause creep deformation even at high temperatures.

  In this respect, as described above, soda glass (E in FIG. 2), quartz glass (F in FIG. 2) and silicon carbide (G in FIG. 2) have a small amount of elastic deformation and also have corrosion resistance as shown in FIG. Therefore, soda glass (E in FIG. 2), quartz glass (F in FIG. 2), and silicon carbide (G in FIG. 2) are suitable as materials for the corrosion-resistant coating layers 5 and 6. It can be said.

Coating Method Test Next, in FIG. 1, the results of the coating method test for a method of coating the surface of one joined body 1 and the other joined body 2 in contact with the corrosive fluid will be described.

  In this coating method test, soda glass (E in FIG. 2) and quartz glass (F in FIG. 2) were coated using glass lining, CVD, and PVD, and silicon carbide (FIG. 2). Five test pieces coated with the CVD method of G) were prepared and subjected to a corrosion test in boiling sulfuric acid.

  In the glass lining method, a soda glass powder whose glass transition temperature is adjusted to about 500 ° C. is made into a slurry form, applied to the surface of a metal substrate by spraying (application process), and then fired at about 800 ° C. Produced (firing process). Since the thickness of the coating produced by the coating process and the firing process is about 100 to 200 μm, the above-described coating process and firing process were repeated to produce a test piece coated with a film having a thickness of about 1 mm. . On the other hand, since it is difficult to form a thick film by the PVD method or the CVD method, the thickness of the film is about 2 to 3 μm.

  As a corrosion test, the same method as described above was used, and each test piece was subjected to a corrosion test for 100 hours in boiling sulfuric acid. In Table 2 below, the case where no corrosion was observed was indicated as “◯”, and the case where corrosion was observed was indicated as “x”.

  From the test results shown in Table 2, all the specimens coated by the glass line method showed no signs of corrosion, but on the other hand, the specimens coated by the CVD method and the PVD method, and carbonized All specimens coated with silicon by CVD were corroded.

  This is because, although any coating method is used for coating, pinhole-like defects are inherent in the coating, but a thick coating can be formed by the glass lining method. The surface does not connect to the base material interface due to the flaws. On the other hand, when the CVD method or PVD method is used, since the thickness of the film formed on the surface is thin, the surface is connected to the substrate interface by a pinhole-like defect, and the metal is connected through the defect. This is probably because the substrate was corroded.

  In addition, the glass lining method has a wide composition selection range, the glass transition temperature is relatively easy to adjust, and creep deformation hardly occurs below the glass transition temperature. It can be said that this is the most suitable method for coating the film.

  Note that, as described above, this glass lining method is used when forming a portion in contact with a corrosive fluid in the surfaces of one joined body 1 and the other joined body 2 in FIG.

  That is, first, a soda glass-based powder is applied to a portion of the surface of one joined body and the other joined body that forms the internal flow path R through which the corrosive fluid flows (application process), and then applied. Soda glass powder is fired (firing step).

  And the part which contacts corrosive fluid among the surfaces of one connection object member 1 and the other connection object member 2 is repeated by repeating the above-mentioned application process and baking process several times. It may be covered with.

Leak Test Next, a leak test performed on the joined body shown in FIG. 1 will be described. The leak test will be described using a joined body having a box shape.

  In FIG. 1, nothing was provided between the flange portion 1a and the bolt 21 and between the flange portion 2a and the nut 22 in the comparative example. On the other hand, in the first embodiment, one Hastelloy disc spring is provided between the flange portion 1a and the bolt 21. In the second embodiment, the flange portion 1a and the bolt 21 and the flange portion 2a and the nut 22 are provided. In the meantime, one disc spring made of Hastelloy was provided.

  As shown in FIG. 1, after the joined bodies 1 and 2 formed by being connected by bolts 21 and nuts 22 are filled with He gas at a pressure of 20 atm, the box is placed in an electric furnace and 500 ° C. After holding for 100 hours, it was cooled to room temperature.

  Such a heat cycle was repeated several times, and the presence or absence of He gas leakage was investigated. Table 3 shows the results of the leak test. In Table 3, “◯” indicates that the He gas did not leak from the container, and “X” indicates that the He gas leaked from the container. Two containers were prepared and the above-described leak test was performed.

  From the results of Table 3, in the comparative example in which no disc spring (loosening prevention mechanism) is provided between the flange portion 1a and the bolt 21 and between the flange portion 2a and the nut 22, the metal is caused by the tightening stress of the bolt 21. It can be seen that the He gas leaks with a relatively small number of heat cycles due to the compression creep deformation of the sealing member 10 and the reduction of the clamping force.

  On the other hand, in the first embodiment in which one Hastelloy disc spring is provided between the flange portion 1 a and the bolt 21, between the flange portion 1 a and the bolt 21 and between the flange portion 2 a and the nut 22. In Example 2 in which one disc spring was provided, it was revealed that almost no He gas leaked from the container even after 50 cycles.

The schematic longitudinal cross-sectional view which shows the structure provided with the seal | sticker connection structure by embodiment of this invention. The graph which shows the result of the test (high temperature corrosion test) regarding the high temperature corrosion property performed in order to select a suitable material as a material used for the corrosion resistant metal layer and corrosion resistant coating layer by embodiment of this invention. The schematic longitudinal cross-sectional view which shows the structure provided with the conventional seal connection structure.

Explanation of symbols

1 One joined body (one connection target member)
2 The other joined body (the other connection target member)
5,6 Corrosion-resistant coating layers 7, 8 Protrusions 10 Metal seal member 11 Seal member body 12 Corrosion-resistant metal layer 20 Fastening portion 21 Bolt 22 Nut 24 Loosening prevention member 40 Seal connection structure 50 Structure R Internal flow path

Claims (6)

Installed between one connection target member and the other connection target member, which forms an internal flow path through which high-temperature corrosive fluid flows, and this one connection target member and the other connection target member are sealed and connected In the seal connection structure
A metal sealing member that is disposed between one connection target member and the other connection target member, and has a seal member body and a corrosion-resistant metal layer that covers the seal member body and contacts a high-temperature corrosive fluid When,
A fastening portion that fastens one connection target member and the other connection target member;
A seal connection structure characterized by comprising:   The seal connection structure according to claim 1, wherein the corrosion-resistant metal layer of the metal seal member is made of gold.   3. The seal connection structure according to claim 1, wherein a thickness of the corrosion-resistant metal layer of the metal seal member is 20 μm or more. One connection mode member forming an internal flow path through which a hot corrosive fluid flows;
The other connection connecting member that is connected to one connection target member and forms an internal flow path through which a high-temperature corrosive fluid flows;
A seal connection structure that is installed between one connection target member and the other connection target member, and seals and connects the one connection target member and the other connection target member;
Seal connection structure
A metal seal member having a seal member main body disposed between one connection target member and the other connection target member, and a corrosion-resistant metal layer that covers the seal member main body and contacts a high-temperature corrosive fluid;
A fastening portion that fastens one connection target member and the other connection target member;
The structure characterized by having.   5. The structure according to claim 4, wherein the one connection target member and the other connection target member have a corrosion-resistant coating layer made of a corrosion-resistant material at least in a portion in contact with the metal seal member. It is the coating | coated method which coat | covers the surface of one connection object member of the structure of Claim 4, and the other connection object member,
An application step of applying a soda glass-based powder to a portion that comes into contact with a corrosive fluid among the surfaces of one connection target member and the other connection target member;
A baking step of baking the applied soda glass-based powder,
By repeating the coating step and the firing step a plurality of times, a portion of the surface of one connection target member and the other connection target member that contacts the corrosive fluid is covered with a glass layer having a desired thickness. A method of covering the structure.

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