JP6902924B2 - Pipe fitting - Google Patents

Description

The present invention relates to a pipe connection that requires a watertight structure, and more particularly to a pipe joint that is suitable for connecting a stainless steel pipe in which a fluid flows inside.

Conventionally, as a pipe joint that requires a watertight structure in a water heater, for example, a male side structure fitted with a ring-shaped sealing material has a large diameter of a female side structure having a curled outer flange portion formed at the tip. A joint structure is known in which a connecting member that is inserted into a cylindrical portion and is removable by elastic deformation is fitted to an outer flange portion to fix both of them. In the connected state between the male side structure and the female side structure, the sealing member is in close contact with the outer surface of the male side pipe and the inner surface of the large diameter portion of the female side structure to ensure watertightness of the connecting part (for example). , Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-316786

In the conventional pipe joint structure as described above, in the connected state, the minute portion surrounded by the outer flange portion of the male side joint end, the outer peripheral surface of the metal pipe, the O-ring, and the inner surface of the large diameter cylindrical portion of the female side joint. A space is formed, and the fluid flowing inside the pipe invades the space. Since the fluid that has entered this space is isolated from the mainstream of the fluid, a stagnation portion is formed. When the material of the piping constituting the male side structure or the female side structure is stainless steel, in addition to the destruction of the corrosion resistant film of the stainless steel by chloride ions contained in the fluid, the dissolved oxygen concentration in the stagnation part and the mainstream part A There is a problem that a potential difference is generated due to the difference in the concentration of stainless steel, and crevice corrosion occurs in the piping material in the minute space.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a pipe joint that suppresses the occurrence of crevice corrosion, which can be suitably used especially in a pipe joint structure of a pipe using stainless steel. It is supposed to be.

The pipe joint according to the present invention has a first pipe having a male side connecting portion formed at the pipe end portion and a second pipe having a female side connecting portion formed at the pipe end portion so that the male side connecting portion can be inserted. Intervening with the pipe so as to be in close contact with the outer peripheral surface of the male side connection portion and the inner peripheral surface of the female side connection portion facing each other when the male side connection portion is inserted into the female side connection portion along the circumferential direction. It is a pipe joint provided with a ring-shaped seal member to be formed, and the male side connection portion includes a first annular pipe expansion portion formed at an axial tip portion thereof and the first annular pipe expansion portion. A second annular pipe expansion portion formed via a seal member mounting portion is provided on the rear side in the axial direction, and the shaft of the first annular pipe expansion portion is provided on the outer peripheral surface portion of the first annular pipe expansion portion. The first pipe that communicates the space in contact with the tip surface in the direction with the minute space formed between the first annular pipe expansion portion in the seal member mounting portion and the seal member mounted in the seal member mounting portion. It is characterized in that a plurality of spiral groove-shaped flow portions having an inclination angle in the circumferential direction with respect to the axial direction of the above are provided in the circumferential direction.
Further, other pipe joints according to the present invention include a first pipe having a male side connecting portion formed at a pipe end portion and a female side connecting portion having a pipe end portion formed so that the male side connecting portion can be inserted. When the male side connection portion is inserted into the female side connection portion, the second pipe having the above is in close contact with the outer peripheral surface of the male side connection portion and the inner peripheral surface of the female side connection portion along the circumferential direction. It is a pipe joint provided with a ring-shaped seal member interposed therein, and the male side connection portion includes a first annular pipe expansion portion formed at the axial tip portion thereof and the first annular pipe expansion portion. A second annular pipe expansion portion formed via a seal member mounting portion is provided on the rear side in the axial direction with respect to the annular pipe expansion portion of the above, and the first annular pipe expansion portion is provided on the outer peripheral surface portion of the first annular pipe expansion portion. The space in contact with the axial tip surface of the pipe expansion portion is communicated with a minute space formed between the first annular pipe expansion portion in the seal member mounting portion and the seal member mounted on the seal member mounting portion. A plurality of groove-shaped flow portions are provided in the circumferential direction, and a plurality of radial through holes are provided in a portion of the peripheral surface of the male side connection portion facing the minute space of the seal member mounting portion. It is characterized by that.

According to the pipe joint of the present invention, when the female side connection portion and the male side connection portion are connected, they are attached to the first annular pipe expansion portion and the seal member mounting portion in the seal member mounting portion of the male side connection portion. A spiral groove-shaped flow portion having an inclination angle in the circumferential direction with respect to the axial direction of the first pipe formed in the first annular pipe expansion portion in the minute space formed between the seal member and the first Since it is connected to the mainstream portion of the fluid in the second pipe, the stagnation of the fluid that has entered the microspace is eliminated, and the difference in dissolved oxygen concentration between the microspace and the mainstream portion is eliminated. As a result, it is possible to suppress the occurrence of crevice corrosion that occurs in the fluid flow portion in the vicinity of the pipe joint, so that there is a remarkable effect that has never been seen before, that is, the reliability of the pipe joint is improved.
Further, according to another pipe joint of the present invention, when the female side connection portion and the male side connection portion are connected, the first annular pipe expansion portion and the seal member mounting portion in the seal member mounting portion of the male side connection portion are connected. A groove-shaped flow part formed in the first annular pipe expansion part connects the minute space formed between the seal member and the seal member mounted on the first and second pipes to the mainstream part of the fluid in the first and second pipes. Since the radial through hole is provided in the portion of the peripheral surface of the male side connection portion facing the minute space of the seal member mounting portion, the stagnation of the fluid that has entered the minute space can be more effectively eliminated. Therefore, the difference in dissolved oxygen concentration between the minute space and the mainstream portion is eliminated. As a result, it is possible to suppress the occurrence of crevice corrosion that occurs in the fluid flow portion in the vicinity of the pipe joint, and there is a remarkable effect that has never been seen before, that is, the reliability of the pipe joint is improved.

The side view which shows the state before connection of the pipe joint which concerns on Embodiment 1 of this invention. A side view showing a connection state in which the first pipe and the second pipe of the pipe joint of FIG. 1 are connected and then fixed by a connecting member. It is a figure which shows the structure of the male side connection part of the 1st pipe shown in FIG. 1, (a) is the front view seen in the axial direction from the pipe end side, and (b) is the side view. The side view which shows the female side connection part of the 2nd pipe in the pipe joint of FIG. A side sectional view showing a connection state in the pipe joint of FIG. It is a figure which shows the male side connection part of the 1st pipe in the pipe joint of Embodiment 2 of this invention, (a) is the front view seen in the axial direction from the pipe end side, (b) is the side sectional view. FIG. 6 is a cross-sectional view in a plane passing through a radial through hole provided in the male side connection portion shown in the pipe joint of FIG. 6 and the central axis of the first pipe. FIG. 5 is a cross-sectional view showing a configuration of a main part in a connected state of a pipe joint according to a second embodiment of the present invention.

Embodiment 1.
1 to 5 show the first embodiment of the present invention, FIG. 1 is a side view showing a state before connection of the pipe joint according to the first embodiment of the present invention, and FIG. 2 is a pipe of FIG. It is a side view which shows the connection state which fixed with the connection member after connecting the 1st pipe and the 2nd pipe of a joint. In addition, in each figure, the same code indicates a member or a part having the same or the same function. In the figure, the pipe joint is formed on a first pipe 1 made of a male side structure, a second pipe 2 made of a female side structure, a ring-shaped seal member 3, and a predetermined portion on the outer peripheral surface of the first pipe 1. After connecting the ring-shaped movable disk 4 movably mounted in the axial direction O of the pipe and the first pipe 1 and the second pipe 2, the connecting member shown in FIG. 2 for maintaining the connected state of the two. It is composed of 5. A male side connection portion 11 is formed at one pipe end portion (left end portion in FIG. 1) of the first pipe 1, and one pipe end portion (right end portion in FIG. 1) of the second pipe 2 to be connected is formed. Is formed with a female side connecting portion 21 formed so that the male side connecting portion 11 of the first pipe 1 can be inserted. The seal member 3 is interposed so as to be in close contact with the outer peripheral surface of the male side connecting portion 11 and the inner peripheral surface of the female side connecting portion 21 along the circumferential direction.

Next, it will be described in more detail with reference to FIGS. 3 to 5. 3A and 3B are views showing the structure of the male side connection portion of the first pipe shown in FIG. 1, FIG. 3A is a front view seen from the pipe end side in the axial direction, and FIG. 3B is a side view. Is. FIG. 4 is a side view showing a female side connection portion of the second pipe in the pipe joint of FIG. 1, and FIG. 5 is a side sectional view showing a connection state of the pipe joint of FIG. The movable disk 4 is not shown in FIG.
The first pipe 1 is, for example, a pipe made of stainless steel and having a wall thickness of about 0.5 mm and having a circular cross section. The first annular pipe expanding portion 11a is formed by, for example, expanding the outer diameter of the pipe by a predetermined size by plastic working using a conventional or known pipe expanding jig. Further, the second annular pipe expansion portion 11b is formed at a predetermined interval from the first annular pipe expansion portion 11a to the rear side in the axial direction of the pipe (right side in FIG. 3B). The outer diameter of the first annular tube expanding portion 11a and the outer diameter of the second annular tube expanding portion 11b are the same.

Further, the shape and structure of the pipe end on the other end side (right side in FIG. 1) of the first pipe 1, the connection destination, the length in the axial direction, and the like are not particularly limited. The circumferential groove portion formed between the first annular tube expansion portion 11a and the second annular tube expansion portion 11b is a seal member mounting portion 11c, and the ring-shaped seal member 3 is fitted and inserted. When the male side connecting portion 11 is inserted into the female side connecting portion 21, the seal member 3 moves to the rear side in the axial direction (to the right in the figure) of the first pipe 1 due to friction, and becomes the first annular pipe expanding portion 11a. A minute space 11d is formed between the seal member 3 and the seal member 3. The outer peripheral surface of the bottom of the seal member mounting portion 11c has a linear contour whose contour line when viewed from the side is parallel to the axial direction O of the first pipe 1, and further, the outer peripheral surface of the bottom thereof has a predetermined surface roughness. By molding on a smooth surface, adhesion with the sealing member 3 can be ensured and appropriate watertightness can be obtained.

Here, as the seal member 3, for example, an O-ring made of a resin having rubber elasticity and expandability is preferably used. As a feature of the first embodiment, a spiral shape in which a space in contact with the axial tip surface B of the first annular pipe expansion portion 11a and a minute space 11d are axially communicated with each other on the outer peripheral surface portion of the first annular pipe expansion portion 11a. The distribution unit 11e of the above is molded. The spiral flow section 11e in the first embodiment is formed in a spiral shape having an inclination angle in the circumferential direction with respect to the axial direction O of the pipe. In FIG. 3, four distribution portions 11e having the same size are provided at equal angles in the circumferential direction of the first pipe 1, but since this is only an example, the shape and inclination angle of the distribution portion 11e The number and the like are not necessarily limited to the form shown in FIG. The first annular pipe expansion portion 11a and the second annular pipe expansion portion 11b have a function of fixing the seal member 3, and also insert the first pipe 1 into the second pipe 2 at the time of assembling with the second pipe 2 described later. It has a function as a guide.

Next, the second pipe 2 which is a female side structure will be described. The second pipe 2 is, for example, a pipe material made of stainless steel and having a wall thickness of about 0.5 mm. A large diameter portion 21a that is larger than the outer diameters of the first and second annular pipe expansion portions 11a and 11b and is expanded to an inner diameter that fits with a predetermined clearance is formed by plastic working, and the peripheral edge of the opening end is formed in the radial direction. A flange portion 21b that has been curled so as to be folded outward is provided. As shown in FIG. 5, the axial dimension of the large diameter portion 21a is formed to the extent that at least the second annular pipe expansion portion 11b fits when the male side connection portion 11 of the first pipe 1 is inserted. Further, by making the inner peripheral surface S of the range a linear shape parallel to the axial direction O of the pipe, the shafts of the pipe can be fitted and inserted without being inclined at the time of assembling with the first pipe 1. Further, by molding the inner surface of the straight portion into a surface smoother than a predetermined surface roughness, it is possible to secure the close contact between the seal member 3 and the inner peripheral surface S of the female side pipe and obtain appropriate watertightness performance. The shape, structure, connection destination, axial length, and the like of the pipe end portion on the other end side (left side in FIG. 1) of the second pipe 2 are not particularly limited.

Next, the connecting member 5 will be described. When assembling the pipe joint, the connecting member 5 is fitted with the male side connecting portion 11 of the first piping 1 into the female side connecting portion 21 of the second piping 2, and is a movable disk of the first piping 1 as shown in FIG. In a state where the flange portion 21b of the second pipe 2 and 4 are butted against each other, both outer sides of the butted portion are elastically engaged so as to be fitted from the outer peripheral side toward the center, and the large diameter portion of the movable disk 4 and the second pipe 2 is engaged. It has a function of fixing 21a and 21a in the axial direction. The movable disk 4 is formed in a ring shape, and is preliminarily assembled so as to be movable in the axial direction O of the first pipe 1 inside the second annular pipe expansion portion 11b of the first pipe 1 in the pipe axial direction. ing.

The movable disk 4 has an inner diameter of a size that fits into the outer peripheral surface closer to the center than the male side connection portion 11 of the first pipe 1, and has an outer diameter of the first annular pipe expansion portion 11a and the first annular pipe expansion portion 11a of the first pipe 1. It is larger than the second annular pipe expansion portion 11b and is substantially the same as the outer diameter of the flange portion 21b at the open end of the second pipe 2. The connecting member 5 is made of, for example, a stainless steel plate having a wall thickness of about 1 mm, has a slit 5a having a width substantially equal to the total thickness of the movable disk 4 and the flange portion 21b, and has a movable disk 4 and a third inside the slit 5a. (2) The flange portion 21b of the pipe 2 is fitted. And it has elasticity that can be attached and detached a plurality of times with respect to the butt portion. The connecting member 5 can be deformed in various ways, and known members such as those described in Japanese Patent Application Laid-Open No. 2008-298175 can be appropriately used.

When the connecting member 5 is attached to the abutting portion between the movable disk 4 attached to the rear end of the male side connecting portion 11 of the first pipe 1 and the flange portion 21b of the female side connecting portion 21 of the second pipe 2, the slit 5a is attached. A part of the butt portion is fitted into the butt portion, and the positional relationship between the movable disk 4 and the flange portion 21b is constrained within the width of the slit 5a, so that the first pipe 1 on the male side and the second pipe 2 on the female side are constrained. It is possible to keep the positional relationship in the axial direction of the above within a predetermined range. When the pressure of the fluid in the pipe fluctuates and becomes higher than the atmospheric pressure, a force acts on the pipe joint portion in the direction of separating the first pipe 1 and the second pipe 2. In such a case, a joint structure in which the male side connection portion 11 of the first pipe 1 is simply inserted into the female side connection portion 21 of the second pipe 2 is easily separated, and the fluid in the pipe leaks out. However, in the joint structure of the first embodiment, the movable disk 4 of the first pipe 1 and the flange portion 21b provided at the end of the large diameter portion 21a of the second pipe 2 are butted by the connecting member 5. Since it is fixed, the positional relationship between the first pipe 1 and the second pipe 2 in the axial direction is maintained within a predetermined range, and it is possible to prevent the liquid tightness from being broken or the joint portion from being separated.

Next, the assembly of the pipe joint will be described. As shown in FIG. 1, with the seal member 3 fitted in the seal member mounting portion 11c of the first pipe 1, the male side connection portion 11 of the first pipe 1 is connected to the female side connection portion 21 of the second pipe 2. When the movable disk 4 of the first pipe 1 is brought into contact with the flange portion 21b of the second pipe 2 by being fitted into the large diameter portion 21a and the connecting member 5 is attached, the state as shown in FIG. 2 is obtained. As a result, the seal member 3 is compressed and closely adhered to the outer peripheral surface of the seal member mounting portion 11c of the first pipe 1 and the inner peripheral surface S of the large diameter portion 21a of the second pipe 2, and is brought into close contact with the first pipe 1 in the pipe joint. Liquid tightness is ensured so that the fluid in the pipe does not leak from the connection portion of the second pipe 2. The compressibility of the seal member 3 is preferably about 8 to 30% of the wire diameter when, for example, an O-ring having a circular cross section is used.

Next, the structure and operation of the spiral circulation portion 11e formed in the first annular pipe expansion portion 11a of the first pipe 1 which is a characteristic portion of the first embodiment of the present invention will be described. As shown in FIG. 5, the spiral flow portion 11e is formed so that a part of the first annular pipe expansion portion 11a forms a constricted groove in the radial direction of the pipe. For example, the depth of the groove is The seal member 3 is formed to have a diameter (minor diameter) of about 50 to 80% in the radial direction when the seal member 3 is used, and the width of the groove is formed to be about the same as the depth of the groove, but the size is not particularly limited. For example, it can be appropriately changed according to the strength determined by the material, wall thickness, diameter, pipe expansion dimension, and the like of the pipe material used as the first pipe 1. Then, it is desirable that the groove portion and the annular pipe expansion portion without a groove are connected by a smooth curve. This is because if the connecting portion between the groove portion and the annular pipe expanding portion without a groove is formed in a square shape, the seal member 3 may be damaged when the seal member 3 is attached. In the first embodiment, the spiral flow portion 11e is formed so as to be inclined with respect to the axial direction O of the pipe, that is, it is spiral in the circumferential direction.

In the pipe joint as in the first embodiment, when the first pipe 1 and the second pipe 2 are connected as shown in FIG. 5, the first annular pipe expansion portion 11a and the first annular pipe expansion portion 11a in the male side connection portion 11 of the first pipe 1 A minute space surrounded by the outer peripheral surface of the seal member mounting portion 11c, the inner peripheral surface S of the large diameter portion 21a of the second pipe 2, and the seal member 3 is formed. In the conventional pipe joint not provided with the spiral groove-shaped flow portion 11e, when the fluid flowing in the pipe invades such a minute space, the invading fluid enters the minute space, particularly the first annular pipe expansion portion 11a. It stayed in a portion corresponding to between the seal member 3 and the rear surface portion of the first annular pipe expansion portion 11a in the seal member mounting portion 11c on the inner side. When the material of the first pipe 1 or the second pipe 2 is stainless steel, if chloride ions are contained in the fluid, in addition to the destruction of the corrosion-resistant coating of the stainless steel, the fluid retention part and the pipe in the minute space A difference in dissolved oxygen concentration occurs between the main stream of the fluid flowing inside, and a corrosive battery is formed due to the difference in concentration, which may cause crevice corrosion in the piping member in the minute space.

On the other hand, in the pipe joint according to the first embodiment, a space in contact with the axial tip surface B of the first annular pipe expansion portion 11a is provided on the outer peripheral surface portion of the first annular pipe expansion portion 11a as a sealing member. The spiral groove-shaped flow portion 11e communicating with the minute space 11d formed between the first annular pipe expansion portion 11a in the mounting portion 11c and the seal member 3 mounted on the seal member mounting portion 11c is separated in the circumferential direction. By providing a plurality of fluids, in this case, four locations, the fluid passing through the flow section 11e obtains a flow velocity in the circumferential direction, so that the fluid invading the minute space 11d also passes through the spiral groove-shaped flow section 11e to the mainstream section. Since it easily enters and exits A, it becomes easy to be agitated and the retention is disturbed, the difference in dissolved oxygen concentration inside and outside the minute space 11d is eliminated, and the occurrence of gap corrosion of the piping member in the minute space 11d is suppressed. The reliability of the pipe joint is improved.

In a water heater or the like that uses a pipe joint consisting of the first pipe 1 and the second pipe 2, even if the opening of the pipe valve or faucet is constant, the pipe connection, bending, water supply, etc. are supplied. Due to pressure fluctuations on the source side, the flow rate, flow velocity, pressure, etc. of the fluid flowing through the piping constantly fluctuate with respect to the time axis. The fluctuation is also caused by the difference in the position (angle) in the circumferential direction between the mainstream portion A and the vicinity portion of the inner peripheral surface S, which is indicated by the white arrow in FIG. 5, and the vicinity portion of the inner peripheral surface S. Differently, since there is unevenness, a pressure difference occurs due to the above-mentioned fluctuation between the plurality of spiral flow portions 11e provided apart from each other in the circumferential direction of the first annular tube expansion portion 11a, and the pressure difference thereof. Along with this, the fluid in the minute space 11d moves in and out of the mainstream portion A in the portion of the circulation portion 11e.

Since the flow section 11e is formed in a spiral shape, the fluid flowing in and out of the spiral flow section 11e promotes the flow of the fluid in the circumferential direction in the minute space 11d, which has the effect of easily suppressing retention. Is obtained. In addition, when the flow portion parallel to the axial direction O of the pipe is simply formed, the rigidity of the portion of the first annular pipe expansion portion 11a in which the flow portion is formed is lower than that of the surroundings. The roundness of the pipe in the mounting portion 11c deteriorates, and the compression ratio of the sealing member 3 such as the O-ring may change in the circumference. As a result, the change in rigidity of the pipe in the circumferential direction of the first annular pipe expansion portion 11a can be suppressed, and the roundness of the seal member mounting portion 11c can be maintained, so that the compression ratio of the seal member 3 is stable and reliable in the circumference. An unprecedented effect of being able to obtain highly liquid-tight performance can be obtained.

Embodiment 2.
6A and 6B are views showing a male side connection portion of the first pipe in the pipe joint of the second embodiment of the present invention, FIG. 6A is a front view seen axially from the pipe end portion side, and FIG. 6B is a side surface. It is a cross-sectional view. FIG. 7 is a cross-sectional view in a plane passing through the radial through hole provided in the male side connection portion shown in the pipe joint of FIG. 6 and the central axis of the first pipe, and FIG. 8 shows the second embodiment of the present invention. It is sectional drawing which shows the structure of the main part in the connection state of the pipe joint. In FIGS. 6 and 7, since the second pipe 2 is the same as that of the first embodiment, the illustration and description will be omitted.
In the figure, the first pipe 1 is, for example, a pipe made of stainless steel and having a wall thickness of about 0.5 mm, and is a pipe end portion (open end) on one end side (left end portion in FIG. 6B) of the pipe. A first annular pipe expansion portion 11a is formed in the portion) in which the outer diameter of the pipe is expanded by a predetermined size by, for example, plastic working using a conventional or known pipe expansion jig. Further, the second annular tube expanding portion 11b is formed at a predetermined interval from the first annular tube expanding portion 11a to the rear side in the axial direction (right side in FIG. 6B). Between the first annular tube expansion portion 11a and the second annular tube expansion portion 11b is a seal member mounting portion 11c, which is a mounting portion of the seal member 3, and a ring-shaped seal member 3 is fitted and inserted.

The outer peripheral surface of the bottom of the seal member mounting portion 11c is formed into a straight surface whose contour line when viewed from the side is parallel to the axial direction O of the first pipe 1 and further smoother than a predetermined surface roughness. By doing so, it is possible to secure the close contact between the seal member 3 and the first pipe 1 and obtain appropriate watertightness. As the sealing member 3, for example, an elastic and stretchable resin O-ring or the like is used. As a feature of the second embodiment of the present invention, a groove-shaped flow portion 11f substantially parallel to the axial direction O is formed on the outer periphery of the first annular tube expansion portion 11a, and the male side connection portion 11 is formed. A plurality of through holes 11g are provided in the circumferential direction through the portion of the peripheral surface facing the minute space 11d in the radial direction. It is desirable that the position of the through hole 11g in the circumferential direction is staggered with respect to the flow portion 11f, but the position is not necessarily limited to that form. For example, in FIG. 6, three distribution portions 11f having the same size are provided at equal angles of 120 ° in the circumferential direction of the pipe, and the through holes 11g are shifted by 60 ° with respect to the mutual installation positions of the distribution portions 11f adjacent to each other in the circumferential direction. However, this is only an example, and the shape, number, position, etc. of the distribution portion 11f and the through hole 11g are not necessarily limited to the form shown in FIG.

The structure of the distribution portion 11f formed in the first annular pipe expansion portion 11a of the first pipe 1 and the structure of the through hole 11g formed in the seal member mounting portion 11c, which is an external feature of the second embodiment of the present invention. The action will be described. As shown in FIG. 6, the circulation portion 11f is formed in a groove shape substantially parallel to the axial direction O in this example so that a part of the first annular pipe expansion portion 11a is constricted inward in the radial direction of the pipe. The depth of the circulation portion 11f is, for example, about 50% of the radial diameter (minor diameter) when the seal member 3 is used, and the width of the circulation portion 11f is about the same as the depth of the groove, but is particularly limited. It's not something. It is desirable that the groove portion and the annular pipe expansion portion without a groove are connected by a smooth curve. This is because if the connecting portion between the groove portion and the annular pipe expanding portion without a groove is formed in a square shape, the seal member 3 may be damaged when the seal member 3 is attached.

As shown in FIGS. 6 to 8, the through hole 11g is formed in a portion of the male side connecting portion 11 on the peripheral surface of the pipe facing the minute space 11d of the sealing member mounting portion 11c. FIG. 7 shows a case where the size of the through hole 11g is about 1 to 2 times the plate thickness of the piping member constituting the first pipe 1, but the shape and number of the through hole 11g are in the pipe. It is appropriately designed according to the density, viscosity, speed, pressure, pipe diameter, size of the flow section, etc. of the fluid flowing through the pipe.

In the pipe joint as in the second embodiment, when the first pipe 1 and the second pipe 2 are connected as shown in FIG. 8, the first annular pipe expansion portion 11a and the first annular pipe expansion portion 11a in the male side connection portion 11 of the first pipe 1 A minute space surrounded by the outer peripheral surface of the seal member mounting portion 11c, the inner peripheral surface S of the large diameter portion 21a of the second pipe 2, and the seal member 3 is formed. In a conventional pipe joint that does not have a groove-shaped flow portion 11f and a through hole 11g, when a fluid flowing in a pipe enters such a minute space, the invading fluid enters the minute space, particularly the first. In the seal member mounting portion 11c on the back side of the annular pipe expansion portion 11a, the seal member 3 and the rear surface portion of the first annular pipe expansion portion 11a stayed in a corresponding portion. When the material of the first pipe 1 or the second pipe 2 is stainless steel, if chloride ions are contained in the fluid, in addition to the destruction of the corrosion-resistant coating of the stainless steel, the fluid retention part and the pipe in the minute space There is a problem that a difference in dissolved oxygen concentration occurs between the main stream portion A of the fluid flowing inside, a corrosive battery is formed due to the difference in concentration, and gap corrosion is caused in the piping member in the minute space 11d.

On the other hand, in the pipe joint according to the second embodiment of the present invention, a space in contact with the axial tip surface B of the first annular pipe expansion portion 11a is provided on the outer peripheral surface portion of the first annular pipe expansion portion 11a. By providing a groove-shaped flow portion 11f that communicates with a minute space 11d formed between the first annular pipe expansion portion 11a of the seal member mounting portion 11c and the seal member 3 mounted on the seal member mounting portion 11c. The fluid that has entered the microspace 11d also enters and exits the mainstream A through the flow section 11f, preventing retention, eliminating the difference in dissolved oxygen concentration inside and outside the microspace 11d, and suppressing the occurrence of crevice corrosion in the microspace. Therefore, the same effect as in the first embodiment that the reliability of the pipe joint portion is improved can be obtained.

Further, in addition to the above effect, in the second embodiment, a plurality of through holes 11g are provided in the circumferential direction through the portion of the peripheral surface of the male side connecting portion 11 facing the minute space 11d in the radial direction. , A pressure difference occurs due to the difference in flow velocity between the flow section 11f and the mainstream A of the through hole 11g, and as shown by the arrow C in FIG. 8, the fluid in the minute space 11d flows mainstream through the flow section 11f and the through hole 11g. The feature is that the exchange of the part A with the fluid is performed more easily. Further, since the through hole 11g is formed so as to be provided so as to be displaced in the circumferential direction with respect to the position of the flow portion 11f, the flow path of the fluid in the minute space 11d indicated by the arrow C is made longer in the circumferential direction. This has the effect of facilitating agitation of the entire fluid in the microspace 11d.

When only the flow section 11f is provided and the through hole 11g is not provided, or when only the through hole 11g is provided and the flow section 11f is not provided, the fluid in the minute space 11d is agitated by the pressure fluctuation of the mainstream section A. However, in the second embodiment of the present invention, since the pressure difference caused by the difference in the flow velocity of the mainstream portion A in the pipe is used, the minute space 11d is used even when the pressure fluctuation of the mainstream portion A itself is small. There is an unprecedented effect of being able to stir the fluid inside and suppress retention. Although FIG. 8 shows that the mainstream portion A flows from the second pipe 2 of the female side pipe to the first pipe 1 of the male side pipe, the flow of the fluid flowing through the pipe is shown. The same effect can be obtained even if the directions are opposite. Further, although the circulation portion 11f is formed substantially parallel to the axial direction O, it may be formed in a spiral shape inclined with respect to the axial direction O as in the first embodiment.

In the present invention, the embodiments can be freely combined, and the embodiments can be appropriately modified or omitted within the scope of the invention.

1 1st pipe, 11 male side connection part, 11a 1st annular pipe expansion part, 11b 2nd annular pipe expansion part, 11c seal member mounting part, 11d microspace, 11e circulation part, 11f circulation part, 11g through hole, 2 2nd pipe, 21 female side connection part, 21a large diameter part, 21b flange part, 3 seal member, 4 movable disk, 5 connection member, 5a slit, A mainstream part, B axis direction tip surface, O axis direction, S Inner circumference.

Claims (4)

A first pipe having a male side connection portion formed at a pipe end portion, a second pipe having a female side connection portion formed at the pipe end portion so that the male side connection portion can be inserted, and the male side connection portion. With a ring-shaped sealing member interposed so as to be in close contact with the outer peripheral surface of the male side connecting portion and the inner peripheral surface of the female side connecting portion facing each other when the female side connecting portion is inserted. The male side connection portion is provided with a first annular pipe expansion portion formed at the axial tip portion thereof and an axial rear side with respect to the first annular pipe expansion portion. A second annular pipe expansion portion formed via the seal member mounting portion is provided, and a space in contact with the axial tip surface of the first annular pipe expansion portion is provided on the outer peripheral surface portion of the first annular pipe expansion portion. Circumferential direction with respect to the axial direction of the first pipe to communicate with the minute space formed between the first annular pipe expansion portion of the seal member mounting portion and the seal member mounted on the seal member mounting portion. A pipe joint characterized in that a plurality of spiral groove-shaped flow portions having an inclination angle are provided in the circumferential direction. A first pipe having a male side connecting portion formed at a pipe end portion, a second pipe having a female side connecting portion formed at the pipe end portion so that the male side connecting portion can be inserted, and the male side connecting portion. With a ring-shaped sealing member interposed so as to be in close contact with the outer peripheral surface of the male side connecting portion and the inner peripheral surface of the female side connecting portion facing each other when the female side connecting portion is inserted. The male side connection portion is provided with a first annular pipe expansion portion formed at the axial tip portion thereof and an axial rear side with respect to the first annular pipe expansion portion. A second annular pipe expansion portion formed via the seal member mounting portion is provided, and a space in contact with the axial tip surface of the first annular pipe expansion portion is provided on the outer peripheral surface portion of the first annular pipe expansion portion. A plurality of groove-shaped flow portions communicating with the minute space formed between the first annular pipe expansion portion of the seal member mounting portion and the seal member mounted on the seal member mounting portion are provided in the circumferential direction. Further, a pipe joint characterized in that a plurality of radial through holes are provided in a portion of the peripheral surface of the male side connecting portion facing the minute space of the sealing member mounting portion in the circumferential direction. The pipe joint according to claim 2, wherein the through hole is provided so as to be displaced in the circumferential direction with respect to the flow portion. A claim, wherein the female side connecting portion includes a cylindrical portion obtained by expanding the pipe end portion of the second pipe, and a flange portion formed by curling the tip end portion of the cylindrical portion. The pipe fitting according to any one of claims 1 to 3.

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