JP3467408B2 - Piping joint for wafer type butterfly valve - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint attached to both end faces of a wafer type (thin type) butterfly valve which is connected to a piping system and has no flanges on both sides.

[0002]

2. Description of the Prior Art In a conventionally known wafer type butterfly valve in which a seat ring is bent to the entire inner peripheral surface and both end surfaces of a main body, the bent portion slightly projects from the valve main body in the pipe axis direction. It is often used that the protruding part acts as a gasket only after the valve body is fastened by the flange attached to the end of the pipe via the long pipe for the pipe to prevent the internal fluid pressure from leaking to the outside. There is. In addition, the flange attached to the end of the above pipe,
The pipes are integrated by welding, screwing, or the like in advance, and these are manufactured in a factory or manufactured locally (on site).

In a general piping system, a small diameter (50A
The screw type is used (refer to Japanese Utility Model Laid-Open No. 4-68267), and the flange type is often used for the medium diameter (inside and outside 200A).

In the case of the above-mentioned screw-in type, the end of the pipe is threaded (male thread) in advance, and a flange having an internal thread formed on the inner surface is screwed into the male thread part. Weld in advance,
Further, in the ring type, it is necessary to weld a predetermined ring to the end of the pipe, which requires a lot of man-hours and causes a cost increase. In addition, the length of the prepared pipe could not be used due to the situation at the site, and the man-hours such as re-welding after cutting were required. On the contrary, if it is too short, it cannot be used.

In the recent piping systems for factories or construction equipment, the large amount of wafer type butterfly valves used from small diameters to medium and large diameters is due to their high reliability and lightweight piping. ) It is considered that this is due to the advantages such as ease of construction. These methods employ a method of fixing flanges to each other with long pipes for piping, but there are problems due to lack of technicians involved in welding work, reliability of the welded part, coating, aesthetics, etc. In particular, in order to make the piping system more convenient, it is said that it is necessary to review the connection joints, that is, the connection between pipes, pipes, valves, and pipes.

Further, as a problem in performing welding work at the site (field), a seat ring inserted into the butterfly valve by joining and fixing locally high temperature flange surfaces after welding to both end surfaces of the butterfly valve. Trouble such as partial deterioration or burnout occurs.

From the corrosion resistance, durability, and aesthetics of the piping system,
The inner and outer surfaces of valves, pipes, and joints may be rust-proofed or powder coated. For this purpose, it is necessary to make the shape including joints single and to reduce the number of parts (for example, Piping bolts etc. have a problem with the threaded part.)

Japanese Utility Model Laid-Open No. 54-174021 discloses means for sealing and connecting the pipe connecting end of a wafer type butterfly valve with a separate member such as a tightening band.

Also, Japanese Utility Model Laid-Open No. 4-68267 discloses a means for fixing the pipe connecting end to the pipe connecting member in advance by screwing or welding.

All of these require secondary processing (ring welding, flange welding, thread cutting, etc.) of the end of the pipe in advance, which requires a large number of steps and causes a cost increase.

[0011]

As described above, in the prior art, it is necessary to fasten and fix both end faces by flanges regardless of the diameter of the wafer type butterfly valve, and the joint with the pipe is integrated by welding. This is generally done, and the number of man-hours has increased due to local (field) production, causing reliability problems and cost increases.

Further, the above-mentioned joining of the flange and the pipe requires a high degree of skill as welding work such as right angle / parallelism, degree of joining of pipe ends, close contact / airtightness, outer diameter / aesthetics, and the like. Workability is significantly affected by the work environment in the (field), welding position, high and low places, etc.

In consideration of the thermal stress at the time of welding, the dimensional accuracy is strict and it is necessary to provide an escape area at the final welding point in the pipe length. The work is extremely inefficient and the working environment is not preferable.

Further, when the connecting portion of the piping system becomes flanges, it is fastened by bolts and nuts. For example, according to JIS standard, JIS5K, JIS10K, JIS
In the case of 16K ..., The predetermined size and quantity are different for each diameter, and unless a large number of bolts and nuts are uniformly tightened over the entire circumference of the flange, the fluid pressure will be leaked to the outside due to one-side tightening.

In order to deal with the above-mentioned problems, a technique for fixing the joint between the flange and the pipe by a method (means) other than welding has already been disclosed. That is, in the joint for inserting the butterfly valve between the pipes, one joint main body that is in pressure contact with the end face of the wafer type butterfly valve through the gasket is a cylindrical shape in which the pipe is fitted, and A plurality of projections whose outer surface is a spiral surface are projected, and a plurality of screw holes are obliquely drilled near the outer end surface of the projection, and a locking screw that engages with the screw holes is provided. The other joint body to be press-contacted is also similarly cylindrical and has a ridge formed around the outer circumference of the inner end surface, and a plurality of screw holes are obliquely formed near the outer end surface thereof and screwed into the screw holes. The engagement ring, which has a locking screw and which is commonly engaged with both joint bodies, has a plurality of claws formed on the outer circumference of the ring, the claws having a groove formed by a spiral surface whose inner surface engages with the spiral surface. ,
Furthermore, projecting projections for striking on the outer circumference of the claw,
A joint for a butterfly valve having an inner surface that is crimped to the outer surface of the projection on the entire circumference of the ring has been disclosed (JP-A-7-833).
No. 41).

[0016] However, in this one, the joint body is brought into contact with both side surfaces of the wafer type butterfly valve, and the projection having the spiral surface formed on the peripheral surface of the inner end of one joint body and the other joint body. The protrusion formed on the outer surface of the inner end portion of the end portion is rotated by rotating the engagement ring having a claw that is screwed into the spiral surface. The above-mentioned claw exerts the same effect as tightening the screw, the other joint body is crimped with the inner surface of the engaging ring over the entire circumference, and the three members are joined together by sandwiching the butterfly valve. However, the two joint bodies and the outer peripheral surface of the pipe are attached to the outer peripheral surface of the pipe by engaging locking screws diagonally near the outer end surfaces of both joint bodies to generate extreme pressure at the screw tips. It is configured to bite locally and firmly engage with that surface. The end surface of the pipe is disposed directly opposite a valve body side.

The present invention secures the joint between the flange and the pipe by a method (means) other than welding, and allows eccentricity (centering) with the pipe and expansion and contraction with a relatively simple structure. An object of the present invention is to provide a pipe joint that eliminates the possibility of applying a strong pressure to the end face of the seat ring during insertion and reliably seals both pipe connection faces of the wafer butterfly valve.

[0018]

In order to solve the above problems, the means adopted by the present invention is to fix a seat ring made of an elastic sealing material on the entire inner peripheral surface of a valve body made of a rigid material and a pipe connecting surface. Then, in a wafer type butterfly valve in which a disc-shaped valve body whose outer peripheral surface comes in contact with and separates from the seat ring is rotatably supported in the valve body, on both pipe connection surfaces of the wafer type butterfly valve body, The end face of the joint body, in which the flange-shaped pipe connection portion and the cylindrical portion having a diameter larger than the pipe are integrally formed, is brought into contact with the end portion, and the valve body and both joint bodies are fastened and fixed by long bolts. At the other end of the joint body, an endless packing is housed in an annular groove formed in the inner circumference of the joint body, and the endless packing is inserted and fixed to the outer peripheral surface of the pipe with a sealing margin, and further, In the end groove that is axially outward from the endless packing A fixing ring having ring-shaped comb teeth formed on the inner peripheral surface in contact with the outer peripheral surface of the pipe is housed and inserted, and the fixing ring is axially pressed to the other end of the joint main body through a ring retainer to fix the pipe. It is fixed by the joint body, and further, an inner diameter enlarged portion that is larger than the pipe outer diameter is formed on the inner peripheral surface of the cylindrical portion of the joint body. Same as the inner diameter of the seat ring on the peripheral surface
Forming a reduced diameter part of equal diameter , the pipe end is the sealing end face
It is characterized in that it is configured so that there is no strong pressure on .

Further, the inner and outer peripheral surfaces of the pipe joint are characterized by anticorrosion treatment or anti-corrosion property, and the pipe connection portion of the pipe joint with the valve body is formed into a 4 to 6-sided shape and long bolts are also used. It is characterized in that the number is set to match the shape.

Further, the endless packing and the fixing ring are formed by endless synthetic rubber or resin molded products.

Further, it is characterized in that the inner diameter of the joint main body for accommodating the endless packing which is inserted and fixed on the outer peripheral surface of the pipe with a sealing margin is slightly larger than the outer diameter of the pipe.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to an embodiment shown in the drawings. 1 shows a front view of a pipe joint of a wafer butterfly valve according to the present invention. The left half of the valve rod center line is an outline drawing, the right half is a sectional view, and FIG. 2 is II- of FIG. II line arrow view, FIG. 3 is I of FIG.
II-III line arrow view, FIG. 5 is an enlarged view of a main part of the portion A of FIG.
FIG. 7 is an enlarged cross-sectional view of the main part of the B section in FIG.

In FIG. 1, a seat ring 2 made of an elastic body is mounted on the inner peripheral surface of a main body (valve main body) 1 of a wafer type butterfly valve, and a disc whose outer peripheral surface contacts and separates from the seat ring 2 when opened and closed. The valve body 3 is attached to the valve rod 5 by the taper bolt 4. As shown in FIG. 8, the seat ring 2 is mounted so that the compression margin C projects from both ends of the main body 1. The amount of protrusion of the compression margin C varies depending on the valve diameter, the material of the seat ring, the hardness, etc., but is generally about 1 to 3 m / m. In this type of butterfly valve, it is not necessary to use a gasket packing, and it is possible to reduce the inconvenience of inserting the gasket packing during the installation work and save the material.

In the present invention, the valve body 1 is connected via the joint body 7 as a means for connecting the valve body 1 and the piping pipe 6 described above.
The pipe body 6 is connected to the pipe body 6, and the joint body 7 is a flange-like pipe connection portion 7a for sandwiching the valve body 1 from both sides at the valve body end and integrally fastening and fixing the valve body 1 with long bolts 8. An intermediate cylindrical portion 7b having a diameter larger than that of the pipe 6 in the middle portion, an endless packing 9 fixed to the outer peripheral surface of the pipe at the other end, and a ring-shaped comb tooth 10a on the inner peripheral surface in contact with the outer peripheral surface of the pipe. Each of the formed fixing rings 10 has an end cylindrical portion 7c housed in an annular groove.

At one end of the joint body 7 on the valve body side, as shown in FIG.
As shown in FIG. 5, the outer surface of the flange-shaped pipe connecting portion 7a has a pipe connecting surface 11 with the valve body 1, and is in pressure contact with the compression margin C of the seat ring 2 for sealing action. Has a reduced diameter 12 smaller than that of the pipe 6, and the intermediate cylindrical body 7b forms an inner diameter enlarged portion 13 having a diameter larger than that of the pipe 6. The end portion 14 is formed in a direction perpendicular to the central axis of the pipe 6,
The end of the pipe 6 contacts the inner end 14.

On the other hand, in the end cylindrical portion 7c of the joint body 7,
As shown in FIG. 5, an endless (endless) synthetic rubber or resin packing 9 having an X-shaped cross section is formed in an annular recess formed in the inner peripheral surface of the joint body 7 with a sealing margin. 6 is attached and fixed to the outer peripheral surface of the pipe 6,
The leakage of the pressure fluid along the outside is prevented. In addition, a ring-shaped comb tooth 10a is formed on the inner peripheral surface in contact with the outer peripheral surface of the pipe in an annular groove formed at the end portion of the endless packing 9 in the axially outer direction. The ring 10 is inserted and fixed to the outer peripheral surface of the pipe, and the ring retainer 15 is attached to the other end portion 17 of the joint body by the hexagon bolt 16.
The ring retainer 10 is pressed in the groove by being screwed in and fastened in the axial direction, and the pipe 6 is fixed by the joint body 7 so as not to come out to the right in the figure, and the endless packing 9 should be used. It also serves as a secondary (second-stage) seal for leaked liquid.

FIG. 6 is an enlarged state diagram before fixing the packing 9 and the fixing ring 10 to the pipe 6, in which the sealing margin D of the packing 9 is smaller than the outer diameter of the pipe 6 in the radial direction. The inner peripheral surface of the packing and the outer peripheral surface of the pipe are brought into close contact with each other by the insertion and attachment so as to prevent the pressure fluid from leaking to the outside. Similarly, the compression margin E of the ring-shaped comb teeth 10a of the fixed ring 10 is formed to have a smaller diameter than the outer diameter of the pipe 6, and the ring-shaped comb teeth 10a formed on the inner surface of the fixed ring 10 are inserted into the pipe 6 so that By abutting on the outer peripheral surface of the pipe 6 and fastening the ring retainer 15 in the axial direction to the other end 17 of the joint body by the hexagonal bolt 16, the fixing ring 10 expands in the radial direction and the entire outer periphery of the pipe 6 is reached. By pressing the surface, the pipe 6 in FIG. 5 is prevented from being pulled out to the right, and at the same time, as described above, the packing 9
It also acts as a secondary seal for the liquid that leaks out.

Incidentally, in FIG. 6, the packing 9 has a cross section X.
However, other cross-sectional shapes may be used as long as they exhibit the same action and effect, such as V-shape and U-shape.
Shape, O shape, etc. may be used. Further, the ring-shaped comb teeth 10a may have a cross-sectional shape other than that shown in the drawing as long as it exhibits the same operation effect, and may be, for example, V-shaped, U-shaped, or wavy. The material of the fixing ring 10 is the above-mentioned synthetic rubber (NBR, EPDM, etc.), and the rubber hardness is JIS
K 6301 spring type hardness test (C type) Hs8
0 to 90 degrees is preferable.

Further, in FIG. 2 (a view taken along the line II-II in FIG. 1), the pipe connecting portion 7a corresponding to the pipe flange has a quadrangular shape, but depending on the valve diameter, a hexagonal shape or a circular shape. The pipe mounting long bolts 8 can be formed in the same shape, and the number of the pipe mounting long bolts 8 is also the same as that of the pipe mounting long bolts 8 with sufficient strength for tightening the protruding portion of the seat ring without external leakage of fluid pressure from the portion. In FIGS. 1 and 2, 1a is a mounting flange for an actuator (not shown), 1b is a bottom plug, 1c is a gland packing, and 5a is an implantation key.

Next, the function and effect of the above embodiment will be described. As shown in FIG. 5, the inner diameter 7-1 of the end inner cylindrical portion 7c connected to the intermediate cylindrical portion 7b having the inner diameter enlarged portion 13 of the joint body 7 is formed to have a size and shape slightly larger than the outer diameter of the pipe 6. By doing so, it is possible to stabilize the pipe in the diameter direction and prevent noise due to vibration of the piping system. Similarly, the inner diameter 15-1 of the ring retainer 15
Is also formed to have a size slightly larger than the outer diameter of the pipe 6.

Further, as shown in FIG. 7, by forming the enlarged inner diameter portion 13 in the intermediate cylindrical portion 7b of the joint body 7, the eccentricity allowance at the time of piping the pipe 6 is absorbed. There is a difference in valve diameter, but the eccentric angle is ± 3 °
Can be absorbed to a degree.

Further, by providing the inner end portion 14 (FIG. 7) of the joint body, the deepest (back) portion at the time of inserting the pipe 6 is determined, and the end portion of the pipe 6 becomes the turning locus of the valve body 3. Are not related to each other, and the pressure and pressure on the end surface of the seat ring 2 are not applied, so that the safety and ease of the piping work can be achieved.

By making the eccentric angle of the pipe and expanding and contracting (long and short) of the pipe as described above, it is suitable as a countermeasure against vibration of the piping system and shaking due to an earthquake, etc., and it is possible to prevent stress concentration and damage to the piping system. it can.

The packing 9 serves to prevent liquid leakage along the pipe 6, and the fixing ring 10 serves to prevent the pipe from being pulled out to the right in the figure. In addition to the advantage that the optimum design can be achieved, the fixing ring 10 having the ring comb teeth 10a on the inner surface is fastened to the ring retainer 15 so as not only to prevent the pipe 6 from being pulled out but also to prevent the endless packing 9 from occurring. It also plays the role of a secondary seal against liquid leakage.

FIG. 4 shows another embodiment of FIG.
It is used when the valve diameter is large, and the shape is 4
Further, not only a hexagonal shape but also a circular shape may be used as long as the action and effect are similar.

Next, due to the corrosion resistance, durability, and aesthetics of the piping system, the inner and outer surfaces of valves, joints, pipes, etc. are increasingly coated with rust or powder, which changes the valve joint method. I'm coming.

In the piping system, corrosion resistance should be maintained so that the fluid does not come into contact with the metal portion on the inner peripheral surface of the pipe, and the pipe mounting position and
Nylon powder coating may be applied to the inside and outside surfaces of pipes considering the weather resistance to the environment. This powder coat has excellent chemical properties, has excellent adhesion to metals, can be used at fluid temperature of up to 80 ° C, and is white or gray based on the aesthetics of the piping system. It is often used, and as a result, painting work after piping is unnecessary and the total cost can be reduced. Another method is epoxy resin powder coating.

As a precaution for piping (installation) work, chamfering the corner of the pipe tip and removing impurities and the like near the packing insertion part will lead to prevention of leakage after insertion. .

[0039]

As described above, according to the present invention,
A seat ring made of an elastic sealing member is fixed to the entire inner peripheral surface of a valve body made of a rigid material and a pipe connecting surface, and a disc-shaped valve body whose outer peripheral surface is brought into contact with and separated from the seat ring is rotatable. In a wafer type butterfly valve axially supported inside, a joint in which a flange-like pipe connecting portion and a cylindrical portion having a diameter larger than that of the pipe are integrally formed at both ends on both pipe connecting surfaces of the wafer type butterfly valve main body The end faces of the main bodies are brought into contact with each other, and the valve main body and both joint main bodies are fastened and fixed by long bolts, and the other end of each joint main body is endless in an annular groove formed in the inner circumference of the joint main body. A packing is accommodated, the endless packing is inserted and fixed to the outer peripheral surface of the pipe with a sealing margin, and further, a ring is formed in the inner peripheral surface that is in contact with the outer peripheral surface of the pipe in the end concave groove axially outward from the endless packing. Insert and fix the fixing ring with comb-shaped teeth , The fixing ring is axially pressed to the other end of the joint main body via a ring retainer to fix the pipe by the joint main body, and the pipe is attached to the inner peripheral surface of the cylindrical portion of the joint main body from the outer diameter of the pipe. to form a larger the inner diameter expanded portion, the valve body side inner end of the large inner diameter portion to form a reduced diameter portion of inner diameter equal to the diameter of the seat ring in the valve body circumferential surface, Pas
The end of the pipe does not press hard against the end face of the seat ring.
With this configuration , the following effects can be achieved.

(I) By attaching and fixing the end face of the joint body to each of the pipe connecting surfaces of the wafer type butterfly valve body with 4 to 6 long bolts, work can be performed by attaching and fastening parts without requiring a skilled worker. Can be completed. In addition, by fixing the joint bodies integrated with the cylindrical portion to both end surfaces of the wafer type butterfly valve body by bolting before piping work, the work of mounting at the site (field) is significantly improved.

(Ii) The endless packing is inserted and fixed to the outer peripheral surface of the pipe with a sealing margin, and a fixing ring having ring-shaped comb teeth on the inner peripheral surface is compressed at the axially outer end thereof. By fixing the pressure in the groove through the ring retainer with a margin, fluid leakage can be sealed across the two stages (secondary) of the endless packing and the fixing ring, and the outer peripheral surface of the pipe can be damaged. It is possible to reliably prevent the pipe from coming off.

(Iii) By providing the inner diameter enlarged portion on the inner surface of the cylindrical portion of the joint body, it is possible to absorb the eccentricity allowance at the time of piping.

(Iv) By providing the reduced diameter portion on the inner diameter end surface of the joint body, when the pipe is inserted, it is possible to push down to this portion, so that there is no strong pressure on the end surface of the seat ring, and the butterfly valve body There is no problem in the rotation of the.

(V) Since no secondary processing such as ring welding, flange welding, and thread cutting at the end of the pipe is required, no welding machine or thread cutting machine is required, and the number of man-hours can be greatly reduced. Since welding work at the site (field) is not required, it is possible to prevent burnout of the seat ring, packing, etc. due to spatter, and to prevent impurities from entering the pipe.

Further, since the inner and outer peripheral surfaces of the joint body are made of a rustproofing treatment or a corrosion resistant material, they can be used stably for a long period of time, and painting can be dispensed with so that the construction cost can be reduced.

Further, since the inner diameter of the joint main body for accommodating the endless packing which is inserted and fixed to the outer peripheral surface of the pipe is fixedly larger than the outer diameter of the packing, the stability of the pipe in the diametrical direction is improved. At the same time, noise due to vibration of the piping system can be prevented.

[Brief description of drawings]

FIG. 1 is a front view of a pipe joint of a wafer butterfly valve showing an embodiment (embodiment) of the present invention, in which a left half portion of a valve rod center line is an external view and a right half portion is a sectional view.

FIG. 2 is a view taken along the line II-II of FIG.

FIG. 3 is a view taken along the line III-III in FIG.

FIG. 4 is a diagram showing another embodiment of FIG.

5 is an enlarged cross-sectional view of a main part of a portion A of FIG.

FIG. 6 is an explanatory view of the sealing of the packing shown in FIG. 5 in an exploded manner.

FIG. 7 is an enlarged cross-sectional view of a main part of a B part in FIG.

FIG. 8 is an explanatory view of sealing the seat ring.

[Explanation of symbols]

1 body (valve body) 2 seat ring 3 valve body 4 taper bolt 5 valve rod 6 pipes 7 Joint body 7a Piping connection 7b Intermediate cylindrical part 7c End cylindrical part 7-1 Joint body inner diameter 8 long bolt 9 packing 10 fixing ring 10a ring-shaped comb teeth 11 Pipe connection surface 12 Reduced diameter 13 Inner diameter expansion part 14 Inner end of joint body 15 ring presser 15-1 Ring retainer inner diameter 16 Hexagon bolt 17 Other end of joint body C compression fee D packing sealing fee E Ring-shaped comb teeth compression allowance

Continuation of the front page (56) References Actual flats 2-36671 (JP, U) Actual opens Sho 49-29515 (JP, U) Actual opens 64-29576 (JP, U) Actual opens Sho 63-115968 (JP , U) Actual development 54-73514 (JP, U) Special public Sho 61-51198 (JP, B2) Actual public 62-46954 (JP, Y2) Actual public 61-18304 (JP, Y2) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16K 27/00-27/12 F16K 1/16-1/226 F16L 17/02 F16L 21/04 F16L 27/12

Claims (5)

(57) [Claims] 1. A disc-shaped valve body having a seat ring made of an elastic sealing member fixed to the entire inner peripheral surface and a pipe connecting surface of a valve body made of a rigid material, and having an outer peripheral surface contacting and separating from the seat ring. In a wafer type butterfly valve that is rotatably supported in the valve body, a flange-shaped pipe connection portion and a cylindrical portion having a diameter larger than the pipe are provided at both ends on both pipe connection surfaces of the wafer type butterfly valve body. The end surfaces of the integrally formed joint body are brought into contact with each other, and the valve body and both joint bodies are fastened and fixed by long bolts, and the other end of each joint body has an annular recess formed on the inner periphery of the joint body. The endless packing is stored in the groove,
The endless packing is inserted and fixed to the outer peripheral surface of the pipe with a sealing margin, and ring-shaped comb teeth are formed on the inner peripheral surface that is in contact with the outer peripheral surface of the pipe in the end groove that is axially outward from the endless packing. The fixing ring is accommodated and inserted, and the fixing ring is axially pressed to the other end of the joint body through the ring retainer so that the pipe is fixed by the joint body. An inner diameter enlarged portion that is larger than the pipe outer diameter is formed on the inner peripheral surface of the portion, and a reduced diameter portion having the same diameter as the inner diameter of the seat ring on the inner peripheral surface of the valve body is formed at the inner end portion of the valve body side of the inner diameter enlarged portion. Form and press the pipe end strongly against the seat ring end face
Pipe joint of the wafer-shaped butterfly valve, characterized by being configured so as not Rukoto. 2. The pipe joint for a wafer type butterfly valve according to claim 1, wherein the inner and outer peripheral surfaces of the pipe joint are made of a rustproof or corrosion resistant material. 3. The pipe connecting portion of the pipe joint with the valve body has four or more pipes.
The pipe joint for a wafer butterfly valve according to claim 1 or 2, wherein the pipe joint has a hexagonal shape and the number of long bolts matches the shape. 4. The pipe joint for a wafer type butterfly valve according to claim 1, wherein the endless packing and the fixing ring are formed of a molded product of endless synthetic rubber or resin. 5. An inner diameter of a joint main body for accommodating an endless packing that is inserted and fixed to the outer peripheral surface of a pipe with a sealing margin,
The pipe joint for a wafer butterfly valve according to any one of claims 1 to 4, wherein the pipe joint is formed slightly larger than the outer diameter of the pipe.