JP6748791B2 - Pipe fitting - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pipe joint, and more particularly, to a pipe joint suitable for use in piping in which a high temperature or low temperature fluid flows.

2. Description of the Related Art A pipe joint including a male pipe joint member and a female pipe joint member for detachably connecting pipes has been conventionally known. Such a pipe joint has a female pipe joint member and a male pipe joint member, for example, as disclosed in Patent Document 1, by inserting the male pipe joint member into the insertion passage of the female pipe joint member. Are connected to each other, and the annular elastic seal member attached to one of the pipe joint members seals the space between the female pipe joint member and the male pipe joint member, and the fluid flowing through the pipe joint leaks to the outside. I try not to. Usually, the elastic seal member is made of a rubber material which has a large elasticity and has a good sealing property.

JP, 2017-129229, A

However, when the temperature of the seal member becomes high by flowing hot oil or the like into the pipe joint, the seal member may be plastically deformed and the space between the pipe joint members may not be sealed. Alternatively, when the temperature of the seal member becomes low by flowing a cryogenic fluid such as liquefied natural gas or liquid nitrogen to the pipe joint, the elasticity of the seal member is lost and the seal member becomes hard, so that the space between the pipe joint members cannot be sealed. is there.

Therefore, it is an object of the present invention to provide a pipe joint capable of maintaining the sealability between the pipe joint members even when the sealability of the elastic seal member is lowered due to high temperature or low temperature.

That is, the present invention is
A pipe joint comprising a first pipe joint member and a second pipe joint member which are detachably connected to each other,
The first fitting member has a first fitting body defining an insertion passage,
The second pipe joint member has a second pipe joint main body that is inserted into the insertion passage in a state of being connected to the first pipe joint member,
One of the first pipe joint member and the second pipe joint member has an elastic seal member that seals between the first pipe joint body and the second pipe joint body in the connected state,
The first fitting body has a first sealing surface, the second fitting body has a second sealing surface facing the first sealing surface in the connected state,
When the first pipe joint body and the second pipe joint body are made of materials having different thermal expansion coefficients, and the first and second pipe joint bodies are heated to a certain temperature or higher in the connected state. Alternatively, when cooled to a certain temperature or less, the first and second pipe joint bodies are thermally expanded or contracted, so that the first seal surface and the second seal surface are pressed against each other and sealingly engaged. To provide a pipe fitting.

In the pipe joint, the elastic seal member mainly seals between the first pipe joint body and the second pipe joint body within a predetermined temperature range, and when the pipe joint is heated to a certain temperature or higher or cooled to a certain temperature or lower. When this is done, the first sealing surface and the second sealing surface are sealingly engaged to seal between the first pipe joint body and the second pipe joint body. Therefore, by providing the sealing engagement by the first and second sealing surfaces before the sealing property of the elastic seal member is lost due to the temperature change, the elastic seal member can maintain the sealing property even in the temperature range where the sealing property cannot be maintained. It becomes possible to maintain the sealing property between the 1st pipe joint main body and the 2nd pipe joint main body, and to prevent the fluid inside from leaking outside.

Specifically, the first sealing surface and the second sealing surface may be formed so as to face each other in the radial direction of the first pipe joint body.

Also,
Further comprising a locking member for restraining a relative position between the first pipe joint body and the second pipe joint body in the coupled state in a direction of a longitudinal axis of the first pipe joint body,
The first sealing surface and the second sealing surface may be formed so as to face each other in the direction of the longitudinal axis of the first pipe joint body.

Or
The second pipe joint body has an insertion passage,
The first pipe joint body has an inner insertion portion that is inserted into the insertion passage of the second pipe joint body in the connected state,
The first pipe joint body has a third seal surface on the outer peripheral surface of the inner insertion portion, and the second pipe joint body faces the third seal surface in the connected state on the inner peripheral surface of the insertion passage. Has a fourth sealing surface,
The first pipe joint body is made of a material having a larger coefficient of thermal expansion than the second pipe joint body, and when the first and second pipe joint bodies are cooled to a certain temperature or lower, The second sealing surface is pressed against each other for sealing engagement, and the third sealing surface and the fourth sealing surface are pressed against each other when the first and second pipe joint bodies are heated to a certain temperature or higher. Or sealingly engaged,
Alternatively, the first pipe joint body is formed of a material having a smaller coefficient of thermal expansion than the second pipe joint body, and the first seal is provided when the first and second pipe joint bodies are heated to a certain temperature or higher. Surface and the second sealing surface are pressed against each other for sealing engagement, and when the first and second pipe joint bodies are cooled below a certain temperature, the third sealing surface and the fourth sealing surface It can also be pressed against each other into a sealing engagement.

With such a configuration, the sealability between the first pipe joint body and the second pipe joint body is maintained in both the low temperature region and the high temperature region where the sealing property of the elastic seal member is lost. Is possible.

Preferably, the elastic seal member is further compressed between the first pipe joint body and the second pipe joint body when the first seal surface and the second seal surface are in sealing engagement. You can

With such a configuration, it is possible to improve the sealing performance of the elastic seal member when the temperature changes.

More preferably, one of the first sealing surface and the second sealing surface may be formed as an annular protrusion protruding toward the other.

With such a configuration, the contact area between the first seal surface and the second seal surface is reduced and the pressing force is concentrated, so that the sealing performance between the first seal surface and the second seal surface is improved. It is possible to improve.

Embodiments of a pipe joint according to the present invention will be described below with reference to the accompanying drawings.

It is sectional drawing in the non-connection state of the pipe joint which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the connection state of the pipe joint of FIG. 1 at normal temperature. It is sectional drawing which shows the connection state at the high temperature of the pipe joint of FIG. It is sectional drawing in the non-connection state of the pipe joint which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the connection state of the pipe joint of FIG. 4 at normal temperature. It is sectional drawing which shows the connection state at the high temperature of the pipe joint of FIG. It is sectional drawing in the non-connection state of the pipe joint which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows the connection state of the pipe joint of FIG. 7 at normal temperature. It is sectional drawing which shows the connection state at the low temperature of the pipe joint of FIG. It is sectional drawing which shows the connection state at the high temperature of the pipe joint of FIG.

As shown in FIG. 1, a pipe joint 100 according to a first embodiment of the present invention includes a female pipe joint member (first pipe joint member) 102 and a male pipe joint member (first pipe joint member) which are detachably connected to each other. 2 pipe joint member) 104.

The female pipe joint member 102 has a cylindrical female pipe joint body (first pipe joint body) 112 having an insertion passage 110 extending in the direction of the longitudinal axis L, and a female pipe joint body 112 that penetrates the female pipe joint body 112 in the radial direction. A spherical lock element (locking member) 118 held in the lock element holding hole 116 provided as well as a sleeve 120 arranged on the outer peripheral surface 112 a of the female pipe joint body 112. The sleeve 120 is displaceable with respect to the female pipe joint body 112 in the direction of the longitudinal axis L, and is biased forward by the spring 122 toward the connecting and holding position in FIG. 1. When the sleeve 120 is in this connecting and holding position, the locking element 118 is supported by the inner peripheral surface 120a of the sleeve 120 from the outside in the radial direction and protrudes inward in the radial direction from the inner peripheral surface 112b of the female pipe joint body 112. Held in position. When the sleeve 120 is displaced rearward against the urging force of the spring 122 and the inner peripheral surface 120a thereof is in the connection releasing position where it does not face the locking element 118, the locking element 118 is displaced radially outward from the locking position and the female is moved. It can be displaced to the unlocked position where it does not project from the inner peripheral surface 112b of the die pipe joint body 112. An annular groove 124 is formed in the inner peripheral surface 112b of the female pipe joint body 112, and an annular elastic seal member 126 is attached to the groove 124. In this embodiment, the elastic seal member 126 is made of a rubber material such as nitrile rubber or silicon rubber, but may be made of another elastic material.

The male pipe joint member 104 has a cylindrical male pipe joint body (second pipe joint body) 132 having a fluid passage 130 extending in the direction of the longitudinal axis L. On the outer peripheral surface 132a of the male pipe joint main body 132, an annular lock element locking groove 134 with which the lock element 118 of the female pipe joint member 102 is engaged is formed.

When the male pipe joint body 132 is inserted into the insertion passage 110 of the female pipe joint body 112 with the sleeve 120 displaced to the connection release position and the sleeve 120 is returned to the connection holding position, the pipe joint 100 is The connected state of FIG. 2 is obtained. In this connected state, the locking element 118 engages with the locking element locking groove 134 and restrains the relative positions of the female fitting main body 112 and the male fitting main body 132 in the direction of the longitudinal axis L. .. In addition, the elastic seal member 126 is compressed between the inner peripheral surface 112b of the female pipe joint body 112 and the outer peripheral surface 132a of the male pipe joint body 132, so that the female pipe joint body 112 and the male pipe joint body. It is sealed with 132.

The female pipe joint body 112 has a first sealing surface 136 on its inner peripheral surface 112b. Further, the male pipe joint main body 132 has an annular projection 138 that projects radially outward toward the first sealing surface 136 on the outer peripheral surface 132 a, and has a second sealing surface 140 on the projection 138. doing. As shown in FIG. 2, the second sealing surface 140 is at a position that faces the first sealing surface 136 in the radial direction in the connected state. In the embodiment, the first sealing surface 136 and the second sealing surface 140 do not come into contact with each other in a connected state at room temperature, but the male pipe joint main body 132 can be inserted into the insertion passage 110. The contact may be made to some extent.

Both the female pipe joint body 112 and the male pipe joint body 132 are made of a metal material, and the female pipe joint body 112 is made of a material having a smaller coefficient of thermal expansion than the male pipe joint body 132. Therefore, when the female pipe joint body 112 and the male pipe joint body 132 are heated by, for example, flowing high-temperature oil into the pipe joint 100, the male pipe joint body 132 has a larger thermal expansion. To do. The female pipe joint body 112 and the male pipe joint body 132 each have a larger diameter due to thermal expansion, but the male pipe joint body 132 expands more than the female pipe joint body 112 due to a difference in thermal expansion coefficient. To do. Therefore, the second sealing surface 140 gradually approaches the first sealing surface 136. At this time, the elastic seal member 126 between the inner peripheral surface 112b of the female pipe joint body 112 and the outer peripheral surface 132a of the male pipe joint body 132 is further compressed in the radial direction, and the female pipe joint body is compressed. The 112 and the male pipe joint main body 132 are more tightly sealed and engaged. When the female pipe joint body 112 and the male pipe joint body 132 are heated to a certain temperature or higher, the first seal surface 136 and the second seal surface 140 are pressed against each other as shown in FIG. Is formed, and the first sealing surface 136 and the second sealing surface 140 are in sealing engagement. As a result, between the female pipe joint body 112 and the male pipe joint body 132, the first seal surface 136 and the second seal surface 140 are also in a state of being hermetically engaged. When the temperature of the female pipe joint body 112 and the male pipe joint body 132 returns to room temperature, the sealing engagement between the first sealing surface 136 and the second sealing surface 140 is released, and the sealing member by the elastic sealing member 126 is released. As a result, the sealing between the female pipe joint body 112 and the male pipe joint body 132 is maintained. In this state, the sleeve 120 is displaced rearward to the connection release position, whereby the locking of the male pipe joint body 132 by the locking element 118 is released, and the female pipe joint member 102 and the male pipe joint member 104 are released. The connection between and can be released. In the state where the first sealing surface 136 and the second sealing surface 140 are sealingly engaged, the first sealing surface 136 and the second sealing surface 136 which are sealingly engaged even if the locking by the locking element 118 is released. The frictional force with the surface 140 maintains the connection. Therefore, the connection is not easily released with the high temperature fluid inside.

Since the rubber material becomes soft and plastically deforms when heated, there is a possibility that the sealing by the elastic seal member 126 formed of the rubber material may not be maintained when the temperature rises to a certain level or higher. In the pipe joint 100, since the first seal surface 136 and the second seal surface 140 can be hermetically engaged with each other in a high temperature state where the hermetic engagement by the elastic seal member 126 cannot be maintained, the elastic seal member 126. Even in a high temperature region where the sealed state cannot be maintained, it is possible to maintain the sealing between the female pipe joint body 112 and the male pipe joint body 132 and prevent the fluid inside from leaking to the outside. The female pipe joint body 112 is made of a material having a larger coefficient of thermal expansion than the male pipe joint body 132, and when the female pipe joint body 112 is cooled to a certain temperature or less, the first seal surface 136 and the second seal surface 136 are generated due to thermal contraction. It is also possible for 140 and 140 to be pressed together into a sealing engagement. In this case, even in a low temperature range in which the sealing engagement by the elastic seal member 126 cannot be maintained, the sealing between the female pipe joint main body 112 and the male pipe joint main body 132 is maintained, and the internal fluid is kept outside. It is possible to prevent the leak.

As shown in FIG. 4, a pipe joint 200 according to a second embodiment of the present invention includes a female pipe joint member (first pipe joint member) 202 and a male pipe joint member (first pipe joint member) which are detachably connected to each other. 2 pipe joint member) 204.

In the pipe joint 200, the tubular female pipe joint body (first pipe joint body) 212 of the female pipe joint member 202 has a radial surface 242 perpendicular to the longitudinal axis L on its inner peripheral surface 212b. The first sealing surface 236 is formed on the radial surface 242. The cylindrical male pipe joint main body (second pipe joint main body) 232 of the male pipe joint member 204 has a second sealing surface 240 on the front end face 243. An annular groove 224 is formed on the front end surface 243 of the male pipe joint body 232, and the elastic seal member 226 is attached to this groove 224.

When the female pipe joint member 202 and the male pipe joint member 204 are connected by the same operation as the pipe joint 100 according to the first embodiment, as shown in FIG. 5, the elastic seal member 226 becomes the female pipe joint. The radial surface 242 of the main body 212 and the groove 224 of the front end surface 243 of the male pipe joint body 232 are hermetically engaged to seal between the female pipe joint body 212 and the male pipe joint body 232. Further, the first seal surface 236 and the second seal surface 240 are at positions facing each other in the direction of the longitudinal axis L. In the embodiment, the first seal surface 236 and the second seal surface 240 are not in contact with each other in the connected state at room temperature, but may be in contact with each other.

In the embodiment, the female pipe joint body 212 is formed of a metal material having a smaller coefficient of thermal expansion than the male pipe joint body 232. Therefore, when the female pipe joint main body 212 and the male pipe joint main body 232 are heated by, for example, flowing high-temperature oil to the pipe joint 200, the male pipe joint main body 232 has a larger thermal expansion. To do. The female pipe joint main body 212 and the male pipe joint main body 232 each have a large length in the longitudinal direction due to thermal expansion, but the male pipe joint main body 232 is the female pipe joint main body due to the difference in thermal expansion coefficient. It becomes longer at a larger rate than 212. Therefore, the distance from the position of the lock 218 fixing the female pipe joint body 212 and the male pipe joint body 232 in the direction of the longitudinal axis L to the second seal surface 240 is up to the first seal surface 236. It becomes longer at a rate larger than the distance, and the second sealing surface 240 gradually approaches the first sealing surface 236. At this time, the elastic seal member 226 between the female pipe joint body 212, the radial surface 242 and the front end face 243 of the male pipe joint body 232 is further compressed in the direction of the longitudinal axis L, and the female die The pipe joint main body 212 and the male pipe joint main body 232 are tightly sealed and engaged with each other. When the female pipe joint body 212 and the male pipe joint body 232 are heated to a certain temperature or higher, the first seal surface 236 and the second seal surface 240 are pressed against each other as shown in FIG. Is formed, and the first sealing surface 236 and the second sealing surface 240 are in sealing engagement. Accordingly, even in a high temperature region where the elastic seal member 226 cannot maintain a sealed state, the sealing between the female pipe joint body 212 and the male pipe joint body 232 is maintained so that the fluid inside does not leak to the outside. It becomes possible. The female pipe joint body 212 is made of a material having a coefficient of thermal expansion larger than that of the male pipe joint body 232, and when the female pipe joint body 212 is cooled to a certain temperature or less, the first seal surface 236 and the second seal surface 236 are contracted due to thermal contraction. 240 and 240 may be pressed together into a sealing engagement.

A pipe joint 300 according to the third embodiment of the present invention shown in FIG. 7 has the following configuration in addition to the configuration of the pipe joint 200 according to the above-described second embodiment. The female pipe joint body (first pipe joint body) 312 of the female pipe joint member (first pipe joint member) 302 has an inner insertion portion 344 extending forward from a radial surface 342 forming the insertion passage 310, The male pipe joint body (second pipe joint body) 332 of the male pipe joint member (second pipe joint member) 304 has an insertion passage 345 that extends in the direction of the longitudinal axis L and communicates with the fluid passage 330. ing. A third seal surface 346 is formed on the outer peripheral surface 344a of the inner insertion portion 344 of the female pipe joint body 312, and a fourth seal is formed on the inner peripheral surface 345a of the insertion passage 345 of the male pipe joint body 332. A surface 348 is formed. In the connected state of FIG. 8, the inner insertion portion 344 of the female pipe joint body 312 is inserted into the insertion passage 345 of the male pipe joint body 332, and the third seal surface 346 and the fourth seal surface 348 are arranged in the radial direction. The positions are opposite to each other.

In this embodiment, the female pipe joint body 312 is made of a metal material having a smaller coefficient of thermal expansion than the male pipe joint body 332. Therefore, when the female pipe joint main body 312 and the male pipe joint main body 332 are heated by pouring high-temperature oil into the pipe joint 300, the male pipe joint main body 332 undergoes a larger thermal expansion. When the female pipe joint body 312 and the male pipe joint body 332 are cooled by flowing a cryogenic fluid such as liquefied natural gas or liquid nitrogen, the male pipe joint body 332 becomes larger. Heat shrinks. When heated, the length in the longitudinal axis L direction of the female pipe joint body 312 becomes larger than that of the male pipe joint body 332 due to the difference in the coefficient of thermal expansion. Therefore, the distance from the position of the lock 318 fixing the female fitting body 312 and the male fitting body 332 in the direction of the longitudinal axis L to the second sealing surface 340 is up to the first sealing surface 336. It becomes longer at a rate larger than the distance, and the second sealing surface 340 gradually approaches the first sealing surface 336. On the other hand, since the male pipe joint body 332 has a larger diameter than the female pipe joint body 312, the third seal surface 346 and the fourth seal surface 348 are separated from each other. When the female pipe joint main body 312 and the male pipe joint main body 332 are heated to a certain temperature or higher, the first seal surface 336 and the second seal surface 340 are pressed against each other as shown in FIG. Are formed, and the first sealing surface 336 and the second sealing surface 340 are in sealing engagement. When the female pipe joint body 312 and the male pipe joint body 332 are cooled, the first seal surface 336 and the second seal surface 340 move away from each other, contrary to the case where they are heated. The third seal surface 346 and the fourth seal surface 348 approach each other. Therefore, when the female pipe joint body 312 and the male pipe joint body 332 are cooled to a certain temperature or less, the third seal surface 346 and the fourth seal surface 348 are pressed against each other as shown in FIG. A metal seal is formed and the third sealing surface 346 and the fourth sealing surface 348 sealingly engage.

In this way, even in a high temperature range where the elastic seal member 326 cannot maintain a sealed state, the sealing between the female pipe joint body 312 and the male pipe joint body 332 is maintained and the internal fluid is prevented from leaking to the outside. It is possible to prevent it, and maintain the seal between the female pipe joint main body 312 and the male pipe joint main body 332 even in a low temperature region where the elastic seal member 326 cannot maintain the sealed state, so that the fluid inside does not come out. It is also possible to prevent the leak. The female pipe joint body 312 is made of a material having a larger thermal expansion coefficient than the male pipe joint body 332, and when heated to a certain temperature or higher, the third seal surface 346 and the fourth seal surface 348 are mutually separated. The first sealing surface 336 and the second sealing surface 340 may be pressed against each other to be sealingly engaged with each other when they are pressed and sealed and cooled to a certain temperature or less.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, the position of the elastic seal member can be appropriately changed, and for example, the elastic seal member may be attached to the male pipe joint member in the first embodiment, or may be attached to the surface facing the direction of the longitudinal axis. Further, although a spherical lock element is used as a locking member for restraining the relative position of the female pipe joint body and the male pipe joint body in the direction of the longitudinal axis, a configuration using a chuck member or Other configurations, such as a configuration in which they are fixed by pins, screws, etc., are also possible. Further, the configuration in which the second seal surface is formed on the protrusion, which is adopted in the first embodiment, can be adopted in other seal surfaces. Further, the respective sealing surfaces may be surfaces inclined with respect to the longitudinal axis so that they are opposed to each other in the radial direction and also in the direction of the longitudinal axis. In the above-described embodiment, both the female pipe joint body and the male pipe joint body are made of a metal material, and the metal seal is formed between the first seal surface and the second seal surface. The first sealing surface and the second sealing surface are in sealing engagement. However, the female pipe joint body and the male pipe joint body may be formed of a relatively hard non-metallic material such as polyether ether ketone (PEEK) other than the metallic material. The sealing engagement between the two sealing surfaces may be provided by abutting such non-metallic materials or abutting such non-metallic and metallic materials. Therefore, the “sealing surface” in the present invention does not necessarily have to be a metal surface.

100 pipe joint 102 female pipe joint member (first pipe joint member)
104 Male pipe joint member (second pipe joint member)
110 insertion passage 112 female pipe joint body (first pipe joint body)
112a Outer peripheral surface 112b Inner peripheral surface 116 Locking element holding hole 118 Locking element (locking member)
Reference Signs List 120 sleeve 120a inner peripheral surface 122 spring 124 groove 126 elastic seal member 130 fluid passage 132 male pipe joint body (second pipe joint body)
132a Outer peripheral surface 134 Locking element locking groove 136 First sealing surface 138 Projection 140 Second sealing surface 200 Pipe joint 202 Female pipe joint member (first pipe joint member)
204 Male pipe joint member (second pipe joint member)
212 Female Fitting Body (First Fitting Body)
212b Inner peripheral surface 218 Locking element 224 Groove 226 Elastic seal member 232 Male pipe joint body (second pipe joint body)
236 1st sealing surface 240 2nd sealing surface 242 radial direction surface 243 front end surface 300 pipe fitting 302 female pipe fitting member (first fitting member)
304 Male pipe joint member (second pipe joint member)
310 Inserting passage 312 Female type pipe joint body (first pipe joint body)
318 Locking element 326 Elastic sealing member 330 Fluid passage 332 Male pipe joint body (second pipe joint body)
336 1st sealing surface 340 2nd sealing surface 342 radial surface 344 inner insertion part 344a outer peripheral surface 345 insertion passage 345a inner peripheral surface 346 third sealing surface 348 fourth sealing surface L longitudinal axis

Claims (4)

A pipe joint comprising a first pipe joint member and a second pipe joint member which are detachably connected to each other,
The first fitting member has a first fitting body defining an insertion passage,
The second pipe joint member has a second pipe joint main body that is inserted into the insertion passage in a state of being connected to the first pipe joint member,
One of the first pipe joint member and the second pipe joint member has an elastic seal member that seals between the first pipe joint body and the second pipe joint body in the connected state,
Further comprising a locking member for restraining a relative position between the first pipe joint body and the second pipe joint body in the coupled state in a direction of a longitudinal axis of the first pipe joint body,
The second pipe joint body has an insertion passage,
The first pipe joint body has an inner insertion portion that is inserted into the insertion passage of the second pipe joint body in the connected state,
The first pipe joint main body has a first seal surface, and the second pipe joint main body faces the first seal surface in the coupled state in the direction of the longitudinal axis of the first pipe joint main body. Has
The first pipe joint member further has a third seal surface on the outer peripheral surface of the inner insertion portion, and the second pipe joint body further connects to the inner peripheral surface of the insertion passage in the connected state with the third seal surface. Has a fourth sealing surface facing each other,
The first pipe joint body is formed of a material having a larger coefficient of thermal expansion than the second pipe joint body, and when the first and second pipe joint bodies are cooled to a certain temperature or lower in the connected state, When the first and second pipe joint bodies are heat-shrinked, the first seal surface and the second seal face are pressed against each other and sealingly engaged, and the first and second pipe joint bodies are heated to a certain temperature or higher. When the first and second pipe joint bodies are thermally expanded when heated, the third sealing surface and the fourth sealing surface are pressed against each other to be sealingly engaged,
Alternatively, when the first pipe joint body is formed of a material having a smaller coefficient of thermal expansion than the second pipe joint body, and the first and second pipe joint bodies are heated to a certain temperature or higher in the connected state. When the first and second pipe joint bodies are thermally expanded, the first seal face and the second seal face are pressed against each other and are sealingly engaged, and the first and second pipe joint bodies have a certain temperature. A pipe joint in which the first and second pipe joint bodies are thermally shrunk when cooled below, so that the third seal face and the fourth seal face are pressed against each other and sealingly engaged. .. And the first seal surface and the second sealing surface, is the inclined surface relative to said longitudinal axis so as also to oppose in the radial direction of the first tube joint body, the pipe joint according to claim 1 .. The elastic seal member is further compressed between the first pipe joint body and the second pipe joint body when the first seal surface and the second seal surface are in sealing engagement. The pipe joint according to claim 1 or 2 . The pipe joint according to any one of claims 1 to 3 , wherein one of the first sealing surface and the second sealing surface is formed as an annular protrusion protruding toward the other.

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