JP4177749B2 - Gas pipe sealing structure - Google Patents

Description

  The present invention relates to a gas pipe sealing structure for sealing a gap between two gas pipes fitted to each other in a rotatable manner with tip parts by a sealing member made of a refractory material. In the present invention, the gas pipe includes not only a normal gas pipe such as an iron pipe but also all tubular pipes through which a gas such as an inflow side or an outflow side end of a gas stopper or a joint flows.

  In general, when two steel gas pipes are connected, first, one end of one gas pipe (second gas pipe) is turnable in the axial direction on the inner periphery of the joint (first gas pipe). Fits immovably. Thereafter, the other gas pipe is screwed into the female thread formed at the other end of the joint. Then, the other gas pipe is screwed and fixed to the joint by rotating the joint. Thereby, two gas pipes are connected.

  By the way, an inevitable gap necessary for allowing the joint to rotate is present between the inner peripheral surface of the joint and the outer peripheral surface of one of the gas pipes rotatably fitted thereto. In order to prevent gas from leaking from the gap, a seal member such as an O-ring is mounted between the inner peripheral surface of the gas pipe and the outer peripheral surface of the joint. However, a sealing member such as an O-ring is melted or burnt out at a high temperature. For this reason, at the time of a fire, there existed a possibility that gas might leak from the clearance gap between the internal peripheral surface of a gas pipe, and the outer peripheral surface of a coupling.

  In order to solve such a problem, in the thing of the following patent document 1, the 1st, 2nd opposing surface which opposes those axial directions is formed in a coupling and a gas pipe, and between these opposing surfaces is formed. A ring-shaped metal seal member is disposed. The seal member has a disc spring shape, and its one end surface and the other end surface are brought into press contact with the first and second opposing surfaces using its own elasticity. Thereby, between 1st, 2nd opposing surfaces is sealed by the sealing member, and by extension, between a gas pipe and a coupling is sealed.

JP 11-142206 A

  When a disc spring-like seal member is used, the accuracy of the width of the seal member (maximum distance between one end surface and the other end surface in the axial direction of the seal member) needs to be high. If the width accuracy of the seal member is low, the amount of elastic deformation of the seal member mounted between the first and second opposing surfaces becomes different for each seal member. As a result, the contact pressure between the seal member and the first and second opposing surfaces varies, which may lead to a situation where a predetermined sealing property cannot be obtained. However, it is relatively difficult to make the width of the disc spring-shaped seal member highly accurate, and if it is attempted to improve the width accuracy, the manufacturing cost of the seal member rises, and consequently the connection between the gas pipe and the joint There was a problem that the cost increased.

In order to solve the above problem, the present invention is configured such that the outer periphery of the distal end of the second gas pipe is fitted to the inner periphery of the distal end of the first gas pipe so as to be rotatable about the rotation axis. And the first gas pipe is formed with first and second opposing surfaces opposed to each other in the rotational axis direction, and is made of a refractory material between the first and second opposing surfaces. An annular seal member that is elastically deformable in the rotational axis direction is provided, and one end and the other end of the seal member in the rotational axis direction are the first and second opposing surfaces due to the elasticity of the seal member itself. The first and second opposing surfaces are sealed by being pressed against each other, and between the first gas pipe and the second gas pipe, the sealing member with respect to the first and second opposing surfaces is sealed. The second gas pipe is moved from the distal end side to the proximal end side by the pressing force. In a gas pipe sealing structure provided with a stopper member for blocking, both end faces of the seal member are planes orthogonal to the rotation axis, and the first and second opposing faces are respectively provided on both end faces of the seal member. The first and second contact portions that come into pressure contact are formed in an annular shape, and the first and second contact portions have different diameters.
In this case, the diameter of the second contact portion may be smaller than the diameter of the first contact portion, or conversely, the diameter may be larger.
When the diameter of the second contact portion is smaller than the diameter of the first contact portion, the first facing surface is formed on the distal end surface of the first gas pipe, and the outer surface is outside the first facing surface. The front end surface of the first gas pipe positioned at is formed in a ring shape with a shielding portion that protrudes forward along the rotation axis and covers the seal member, and the seal member is radially outward of the first gas pipe. In order to prevent the first gas pipe from being visible, the distal end of the shielding portion in the direction from the proximal end side to the distal end side of the first gas pipe is positioned forward of the distal end of the seal member in the same direction. desirable.
Further, the stopper member is provided on the outer peripheral surface of the second gas pipe so as not to rotate, and the stopper member faces the inner peripheral surface of the first gas pipe from the distal end side to the proximal end side of the second gas pipe. It is desirable that an annular engagement portion for preventing the second gas pipe from moving from the distal end side to the proximal end side by abutting against one end surface of the gas pipe is formed.
The stopper member can be enlarged or reduced in diameter by forming a notch portion reaching from the inner peripheral surface to the outer peripheral surface in a part thereof, and is fitted to the outer peripheral surface of the second gas pipe in the expanded state. Accordingly, it is impossible to rotate with respect to the second gas pipe, and the angle between the both side surfaces that define the notch in the circumferential direction of the stopper member and the inner peripheral surface of the stopper member becomes an obtuse angle, The stopper member is inclined so that an angle formed with the outer peripheral surface of the stopper member is an acute angle, and an annular projecting portion that abuts against the inner peripheral portion of the one end surface of the stopper member is formed on the inner peripheral portion of the annular engaging portion. It is desirable that it be formed.
The contact surface pressure of the seal member with respect to the first and second contact portions is set to 2.5 N / mm ² or more, and the maximum torque when the first and second gas pipes are stationary is 0.7 N · m or less. It is desirable to be set to.

  According to the present invention having the above-described characteristic configuration, the variation in contact pressure between the seal member and the first and second contact portions can be reduced, and thereby the sealing performance between the first and second opposing surfaces is constant. In addition, it is possible to obtain an effect that the gas pipes can be connected at a low cost.

The best mode for carrying out the present invention will be described below with reference to the drawings.
1 to 5 show an embodiment of the present invention. As shown in FIG. 1, in this embodiment, a gas pipe sealing structure according to the present invention includes an iron gas pipe (second gas pipe) 1 and a distal end portion (left end in FIG. 1) of the gas pipe 1. In the following description, the right and left are assumed to mean the left and right in FIG. 1), and the right end (tip portion) is fitted so as to be rotatable about the rotation axis L (first gas pipe) 2. It is applied between. Of course, this invention is applicable also to the sealing structure of the gas pipes connected so that rotation other than the gas pipe 1 and the coupling 2 mutually is possible.

  The gas pipe 1 has a circular cross section, and a fitting portion 11 is formed at the left end thereof. The outer diameter of the fitting portion 11 is smaller than the outer circumference of the gas pipe 1 on the right side (base end side). As a result, a step surface (second facing surface) 12 extending annularly about the rotation axis L is formed between the outer peripheral surface of the proximal end portion of the fitting portion 11 and the outer peripheral surface of the gas pipe 1 on the right side thereof. Is formed. The step surface 12 is a plane orthogonal to the rotation axis L.

  On the other hand, a fitting hole 21 is formed at the right end (tip) of the inner peripheral surface of the joint 2. The inner diameter of the fitting hole 21 is smaller than the inner peripheral surface of the joint 2 on the left side (base end side) of the fitting hole 21. As a result, a step surface (annular engagement portion) extending annularly about the rotation axis L between the inner peripheral surface of the fitting hole portion 21 and the inner peripheral surface of the joint 2 on the left side of the fitting hole portion 21. ) 22 is formed. A tapered female thread portion 26 is formed at the left end portion of the inner peripheral surface of the joint 2. To the tapered female thread portion 26, another iron gas pipe (not shown) is screwed and fixed. As a result, the other gas pipe is rotatably connected to the gas pipe 1 via the joint 2. Other gas pipes can be easily connected to the joint 2 by rotating the joint 2. Instead of the taper female thread portion 26 on the inner peripheral surface of the left end portion of the joint 2, other connection means, for example, a connection device for a flexible gas pipe may be provided.

  The fitting portion 11 of the gas pipe 1 is inserted into the fitting hole portion 21 of the joint 2 from the right end opening, and the fitting portion 11 rotates about the rotation axis L in the fitting hole portion 21. It can be fitted. Between the outer peripheral surface of the fitting part 11 and the inner peripheral surface of the fitting hole part 21, the sealing materials 3 and 4 which have elasticity, such as O-rings which consist of resin etc., are mounted | worn. Thereby, the gas is prevented from leaking from an inevitable gap formed between the outer peripheral surface of the fitting portion 11 and the inner peripheral surface of the fitting hole portion 21.

  A locking recess 13 is formed at the left end of the outer peripheral surface of the fitting portion 11 so as to extend annularly along the circumferential direction. A stopper member 5 is attached to the locking recess 13. As shown in FIG. 3, the stopper member 5 is configured by forming a notch 51 in a part of a ring body made of a metal plate material. By forming the notch 51, the stopper member 5 can be expanded and contracted. The inner diameter of the stopper member 5 is smaller than the diameter of the bottom surface of the locking recess 13 in a natural state where no external force acts on the stopper member 5. Accordingly, the stopper member 5 is fitted to the bottom surface of the locking recess 13 in an elastically expanded state, and friction generated between the inner peripheral surface 52 of the stopper member 5 and the bottom surface of the locking recess 13. Thus, the rotation of the stopper member 5 in the circumferential direction is prevented. Of course, the stopper member 5 can be rotated against the frictional resistance acting between the inner peripheral surface 52 and the bottom surface of the locking recess 13, but the connection between the gas pipe 1 and the joint 2 is possible. The stopper member 5 does not rotate in the state where the above is completed. Therefore, the stopper member 5 is substantially unrotatable with respect to the fitting portion 11 of the gas pipe 1. The outer diameter of the stopper member 5 is larger than the outer diameter of the fitting portion 11. Therefore, the outer peripheral portion of the stopper member 5 protrudes radially outward from the locking recess 13.

  As shown in FIG. 3B, the stopper member 5 is formed in a spiral shape, and its axial length is slightly longer than the width of the locking recess 13. This prevents the stopper member 5 from rattling in a state where the stopper member 5 is mounted in the locking recess 13. The stopper member 5 is elastically deformed into a flat plate shape as is apparent from FIG. 1 in a state where the connection between the gas pipe 1 and the joint 2 is completed. Therefore, the stopper member 5 may be formed in a flat plate shape as shown in FIG. The stopper member 5 is prevented from moving further to the left (in the direction of insertion of the fitting portion 11 into the fitting hole portion 22) by abutting against the left side surface of the locking recess 13.

  The stopper member 5 has a side surface 51a that defines the notch 51 so that the angle formed by the one side surface 51a and the inner peripheral surface 52 is an obtuse angle and the angle formed by the one side surface 51a and the outer peripheral surface 53 is an acute angle. It is a plane inclined with respect to a line (diameter line) passing through the center of. The other side surface 51 b that defines the notch 51 is formed symmetrically with the one side 51 a with respect to a radial line passing through the center in the circumferential direction of the notch 51. Therefore, the angle formed by the other side surface 51b and the inner peripheral surface 52 is also an obtuse angle, and the angle formed by the other side surface 51b and the outer peripheral surface 53 is also an acute angle. The obtuse angle between the one side surface 51a and the other side surface 51b and the inner peripheral surface 52 is that the outer peripheral surface of the fitting portion 11 is damaged by the intersections of the one side surface 51a, the other side surface 51b and the inner peripheral surface 52. This is to prevent the damage. That is, when the stopper member 5 is mounted in the locking recess 13, the diameter of the stopper member 5 is increased, and the fitting member 11 is extrapolated from the left end. At this time, if the angle formed by the intersecting portions of the one side surface 51a and the other side surface 51b and the inner peripheral surface 52 is 90 ° or an acute angle, the outer peripheral surface of the fitting portion 11 may be damaged by the intersecting portions. . In order to prevent such a situation from occurring, the angles formed by the one side surface 51a and the other side surface 51b and the inner peripheral surface 52 are obtuse.

  In a state where the stepped surface 22 of the joint 2 abuts against the stopper member 5 and the entire inner periphery thereof is abutted against the left side surface of the locking recess 13, the right end surface (first opposing surface) 23 of the joint 2 is the gas pipe 11. Is opposed to the step surface 12 with a gap in the direction of the rotation axis L. The seal member 6 is disposed between the step surface 12 and the right end surface 23. The seal member 6 is made of a metal thin plate material such as stainless steel having spring properties, and is formed in a ring shape. The inner diameter of the seal member 6 is equal to or slightly larger than the outer diameter of the fitting portion 11 so that the sealing member 6 can be extrapolated from the left end portion of the fitting member 11. The outer diameter in the vicinity of the right end surface 23 of the joint 2 is set to be the same as the outer diameter of the outer peripheral surface on the right side of the step surface 12 of the gas pipe 1. The outer diameter of the seal member 6 is smaller than the outer diameter of the right end portion of the joint 2. Both end surfaces of the seal member 6 are flat surfaces orthogonal to the rotation axis L.

  An annular protrusion (second contact portion) 14 that protrudes along the rotation axis L toward the right end surface 23 side of the joint 2 is formed on the inner peripheral portion of the step surface 12 of the gas pipe 1. The annular projecting portion 14 is formed in an annular shape with the rotation axis L as a center, and the tip surface 14 a is a plane orthogonal to the rotation axis L. Therefore, the outer peripheral surface 14b and the front end surface 14a of the annular protrusion 14 intersect at a right angle. On the other hand, on the outer peripheral portion of the right end surface 23 of the joint 2, an annular projecting portion (first abutting portion) 24 that projects toward the stepped surface 12 side of the gas pipe 1 along the rotation axis L is formed. The annular protrusion 24 is formed in an annular shape with the rotation axis L as a center, and the front end surface 24 a is a plane orthogonal to the rotation axis L. Therefore, the inner peripheral surface 24b and the front end surface 24a of the annular protrusion 14 intersect at a right angle. The inner diameter of the annular protrusion 24 is larger than the outer diameter of the annular protrusion 14.

  When the stepped surface 22 of the joint 2 abuts against the stopper member 5 and the entire inner peripheral portion thereof abuts against the left side surface of the locking recess 13, the tip surface 24 a of the annular projecting portion 24 is The distal end surface 14a is located on the right side of a specific virtual position separated to the left by at least the thickness of the seal member 6. Moreover, since the outer diameter of the annular protrusion 14 is larger than the inner diameter of the seal member 6 and the inner diameter of the annular protrusion 24 is smaller than the outer diameter of the seal member 6, the right end surface of the seal member 6 The annular projecting portion 14 abuts on the inner peripheral side portion, and the annular projecting portion 24 abuts on the outer peripheral side portion of the left end surface of the seal member 6. As a result, the seal member 6 is elastically deformed in the direction of the rotation axis L by at least the distance that the distal end surface 24a is spaced to the right with respect to the virtual position. In particular, in this embodiment, since the front end surface 24a of the annular projecting portion 24 is located on the right side of the front end surface 14a of the annular projecting portion 14, the seal member 6 has at least the thickness of the seal member 6 itself and the annular projecting portion. The portions 14 and 24 are elastically deformed in the direction of the rotation axis L by the sum of the distances between the tip surfaces 14a and 24a. The elastically deformed seal member 6 has its right end surface pressed against the front end surface 14a of the annular projecting portion 14 in an annular manner and its left end surface pressed against the front end surface 24a of the annular projecting portion 24 by its own elastic force. Let Thereby, the gap between the step surface 12 of the gas pipe 1 and the right end surface 23 of the joint 2 is hermetically sealed. Moreover, as a result of the joint 2 being pushed to the left by the elastic force of the seal member 6, the stepped surface 22 hits the right end surface of the stopper member 5, and the entire inner peripheral portion of the left end surface of the stopper member 5 is the left side of the locking recess 13. It is maintained in a state where it hits the surface. As a result, the joint 2 is prevented from coming out from the fitting portion 11 of the gas pipe 1 to the left.

Here, the contact surface pressure of the seal member 6 with respect to the front end surfaces 14a and 24a is determined by the elastic deformation amount of the seal member 6, and the elastic deformation amount of the seal member 6 is the rotation axis L between the front end surface 14a and the front end surface 24a. It is determined by the positional relationship in the direction. The positional relationship between the distal end surface 14a and the distal end surface 24a is such that the contact surface pressure with the seal member 6 is lower among the annular projecting portions 14 and 24 (in this embodiment, the annular projecting portion 24 is larger than the annular projecting portion 14). Since it is a diameter, it is set to a positional relationship such that the contact surface pressure of the annular protrusion 24.) is ^2.5 N / mm ² or more. This is because if the contact surface pressure is less than ^2.5 N / mm ² , the seal member 6 may not be able to prevent gas leakage. On the other hand, when the contact surface pressure is excessively increased, in other words, the amount of elastic deformation of the seal member 6 is increased and the pressing force of the seal member 6 against the gas pipe 1 and the joint 2 is excessively increased, the seal member 6 and the gas The frictional resistance acting between the pipe 1 and the joint 2 and the frictional resistance between the stopper member 5 and the stepped surface 22 of the joint 2 become excessively large, and the joint 2 is smoothly rotated with respect to the gas pipe 1. It can no longer be moved. Therefore, the seal member 6 is elastically deformed so that the rotation torque required for rotating the joint 2 with respect to the gas pipe 1 is 0.7 N · m or less, and the seal member 6 is elastically deformed as such. The positional relationship between the front end surfaces 14a and 24a is determined so that they can be made.

  In this embodiment, the tip surface 14a and the outer peripheral surface 14b of the annular protrusion 14 intersect at a right angle, and the tip surface 24a and the outer periphery 24b of the annular protrusion 24 intersect at a right angle. The right end surface of the seal member 6 is in line contact with the intersecting portion between the tip surface 14a and the outer peripheral surface 14b in an annular shape, and the left end surface of the seal member 6 is annular at the intersecting portion between the tip surface 24a and the outer peripheral surface 14b. The tip surfaces 14a, 24a are brought into surface contact with the seal member 6 by making the tip surfaces 14a, 24a conform to the shape of the elastically deformed seal member 6. May be.

  A shielding portion 25 that protrudes toward the stepped surface 12 of the gas pipe 1 is formed on the outer peripheral portion of the tip surface 24 a of the annular protrusion 24 of the joint 2. The shielding portion 25 extends in an annular shape around the rotation axis L, and the inner diameter thereof is larger than the outer diameter of the seal member 6. Moreover, the front end surface (right end surface) 25a of the shielding portion 25 is located on the right side of the portion located on the rightmost side of the seal member 6 (the intersection between the right end surface of the seal member 6 and the outer peripheral surface). As a result, the shielding part 25 covers the sealing member 6 so that it cannot be seen from the outside in the radial direction of the joint member 2. Thereby, the improvement of aesthetics is aimed at.

  In the sealing structure between the gas pipe 1 and the joint 2 configured as described above, since both end faces of the seal member 6 are flat, the thickness dimension can be easily made highly accurate. Therefore, the variation in the contact pressure between the seal member 6 and the annular projecting portions 14 and 24 can be suppressed to be small. In addition, since the thickness accuracy of the seal member 6 can be easily improved, the seal member 6 can be manufactured at a much lower cost compared to the case of manufacturing a disc spring-shaped seal member having the same width accuracy. . Therefore, the connection cost between the gas pipe 1 and the joint 2 can be reduced.

  FIG. 6 shows another embodiment of the present invention. In this embodiment, a contact portion 22a protruding toward the stopper member 5 is formed in an annular shape on the inner peripheral portion of the contact surface of the stepped surface (annular engagement portion) 22 of the joint 2 with the stopper member 5. Has been. Therefore, in this embodiment, the entire portion of the step surface 22 facing the stopper member 5 does not contact the stopper member 5, and only the contact portion 22 a contacts the stopper member 5.

  Thus, when the contact part 22a formed in the inner peripheral part of the level | step difference surface 22 is made to contact the stopper member 5, the whole surface facing the stopper member 5 of the level | step difference surface 22 is the stopper member 5 in the whole. Since the effective contact diameter of the step surface 22 with respect to the stopper member 5 is smaller than that in the above-described embodiment, the frictional resistance acting between the step surface 22 and the stopper member 5 is reduced, thereby The rotational torque required to rotate the joint 2 can be reduced. In addition, in the case of the above embodiment, the stepped surface 22 is in contact with the intersecting ridge between the one side surface 51 a of the stopper member 5 and the outer peripheral surface 53, so that the acute angle between each side surface 51 a, 51 b and the outer peripheral surface 53 is increased. Touch the intersection. For this reason, when the joint 2 is rotated in the forward / reverse direction, one of the two intersecting portions forming an acute angle between the side surfaces 51a, 51b and the outer peripheral surface bites into the stepped surface 22, and the joint 2 is smoothly rotated. Inhibit. In this respect, in this embodiment, since the outer diameter of the contact portion 22a is smaller than the outer diameter of the stopper member 5, each intersection of the side surfaces 51a, 51b and the outer peripheral surface 53 becomes the step surface 22. There is no contact. Therefore, the joint 2 can be rotated more smoothly.

It is sectional drawing which shows the principal part of one Embodiment of this invention. It is an enlarged view of the X circle part of FIG. It is a figure which shows the stopper member used in the embodiment, Comprising: FIG. 3 (A) is the top view, FIG.3 (B) is a B arrow view of FIG. 3 (A). It is a figure similar to FIG. 3 (B) which shows the other example of a stopper member. It is a figure which shows the sealing member used in the embodiment, Comprising: FIG. 5 (A) is the top view, FIG.5 (B) is a B arrow view of FIG. 5 (A). It is sectional drawing which shows the principal part of other embodiment of this invention.

Explanation of symbols

L Rotation axis 1 Gas pipe (second gas pipe)
2 Fitting (first gas pipe)
5 Stopper member 6 Seal member 12 Step surface (second facing surface)
14 Annular protrusion (second contact part)
22 Step surface (annular engagement part)
22a Contact part (annular protrusion)
23 Right end surface (first facing surface)
24 annular protrusion (first contact part)
25 Shielding part 51 Notch part 51a (Partitioning the notch part) Side face 51b (Partitioning the notch part) Side face 52 (Stopper member) Inner peripheral surface 53 (Stopper member) outer peripheral surface

Claims (6)

The outer periphery of the distal end of the second gas pipe is fitted to the inner periphery of the distal end of the first gas pipe so as to be rotatable about the rotational axis, and the distal ends of the first gas pipe and the second gas pipe are First and second opposing surfaces facing each other in the rotational axis direction are formed, and an annular seal member made of a refractory material and elastically deformable in the rotational axis direction is formed between the first and second opposing surfaces. And the one end and the other end of the seal member in the rotation axis direction are in press contact with the first and second opposing surfaces by the elasticity of the seal member itself, respectively. The space between the two opposing surfaces is sealed, and the second gas tube is inserted from the tip side between the first gas tube and the second gas tube by the pressing force of the seal member against the first and second opposing surfaces. Gas pipe provided with a stopper member that prevents movement to the base end side In sealing structure,
Both end surfaces of the seal member are flat surfaces orthogonal to the rotation axis, and first and second contact portions that are in pressure contact with the both end surfaces of the seal member are formed annularly on the first and second opposing surfaces, respectively. A gas pipe sealing structure characterized in that the first and second contact portions have different diameters. 2. The gas pipe sealing structure according to claim 1, wherein a diameter of the second contact portion is smaller than a diameter of the first contact portion. The first opposed surface is formed on the distal end surface of the first gas pipe, and the distal end surface of the first gas pipe located outside the first opposed surface projects forward along the rotational axis. A shielding portion that covers the seal member is formed in an annular shape, and the seal member in a direction from the proximal end side to the distal end side of the first gas pipe is arranged so that the seal member cannot be seen from the radially outer side of the first gas pipe. The gas pipe sealing structure according to claim 2, wherein the front end of the shielding portion is positioned in front of the front end of the seal member in the same direction. The stopper member is non-rotatably provided on the outer peripheral surface of the second gas pipe, and the stopper member is disposed on the inner peripheral surface of the first gas pipe so as to face the base end side from the distal end side of the second gas pipe. The annular engagement part which prevents that the said 2nd gas pipe moves from the front end side to the base end side by abutting against an end surface is formed, The any one of Claims 1-3 characterized by the above-mentioned. Gas pipe sealing structure. The stopper member can be enlarged or reduced in diameter by forming a notch portion reaching from the inner peripheral surface to the outer peripheral surface in a part thereof, and is fitted to the outer peripheral surface of the second gas pipe in the expanded state. Accordingly, it is impossible to rotate with respect to the second gas pipe, and the angle between the both side surfaces that define the notch in the circumferential direction of the stopper member and the inner peripheral surface of the stopper member becomes an obtuse angle, The stopper member is inclined so that an angle formed with the outer peripheral surface of the stopper member is an acute angle, and an annular projecting portion that abuts against the inner peripheral portion of the one end surface of the stopper member is formed on the inner peripheral portion of the annular engaging portion. The gas pipe sealing structure according to claim 4, wherein the gas pipe sealing structure is formed. The contact surface pressure of the seal member with respect to the first and second contact portions is set to 2.5 N / mm ² or more, and the maximum torque when the first and second gas pipes are stationary is 0.7 N · m or less. The gas pipe sealing structure according to claim 1, wherein the sealing structure is a gas pipe sealing structure.

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