JP6611127B2 - Non-bolt joint structure of fluid pipe - Google Patents

Description

  The present invention relates to a non-bolt joint structure for a fluid pipe such as a water pipe.

  Iron-based metal pipes buried in the ground are coated. For example, epoxy coating or powder coating is applied as an anticorrosion coating on the inner and outer surfaces of a joint body for water supply to prevent corrosion.

One type of corrosion is a natural phenomenon called electric corrosion. Electrolytic corrosion is a type of electrolysis in which a dissimilar metal becomes a pair of electrodes, and there is a direct current power source, and ionized iron is eluted when the inflowing current flows out into the soil.

Such electrolytic corrosion is particularly likely to occur at sharp points such as the tip of the bolt or the surface of the screw. Therefore, when connecting the first fluid pipe and the second fluid pipe of different metals, a non-bolt joint structure that does not use a bolt is desirable.

Various structures are known as non-bolt joint structures. (Patent Documents 1 to 3)

JP1-174690Y (front page) JP11-201343A (front page) JP2008-303901A (front page)

When the diameter of the fluid pipe is expanded by the bulge method, the coating film needs to be stretched according to the elongation of the metal pipe. At that time, stress (tension) is applied to the coating film.

On the other hand, the fluid pipe provided with the engagement means for preventing the separation is an engagement portion due to fluctuations in internal pressure or uneven settlement of the ground, the distal end portion of the insertion portion, the rear end portion of the receiving portion, and the portion close to the opening A large static load or impact force is applied to the In that case, cracks and cracks may occur in the coating film of these parts. The occurrence of cracks or the like tends to cause electrolytic corrosion on one of the different metals.

Accordingly, an object of the present invention is to prevent electrolytic corrosion of a fluid pipe in a non-bolt joint structure in which one fluid pipe is expanded by a so-called bulge method.

That is, according to the present invention, the insertion port 20 of the second fluid tube 2 made of stainless steel or steel is inserted into the receiving port 10 of the first fluid tube 1 made of cast iron, and bolts are used between the two tubes. Non-bolt joint structure of fluid pipes connected to each other,
A resin-made coating film P formed on the inner peripheral surface 11 of the receiving portion 10 and the outer peripheral surface 21 of the insertion portion 20;
A rubber seal ring SR that is inserted between the receiving portion 10 and the insertion portion 20 and seals between the receiving portion 10 and the insertion portion 20;
A first engagement portion E1 provided on the inner periphery of the receiving port 10 engages with a second engagement portion E2 on the outer periphery of the second fluid pipe 2 in the tube axial direction S, so that both the fluid pipes 1 , 2 and engaging means E for preventing the two from separating from each other,
The second fluid pipe 2 has a bulging portion 23 that is plastically deformed and expanded in diameter toward the outer side R1 in the radial direction.
The second engagement portion E2 is disposed in a part of the bulge portion 23,
The coating film P of the first engagement part E1 and the coating film P of the second engagement part E2 are directly inserted between the first engagement part E1 and the second engagement part E2. A resin-made first insulating ring 31 for preventing contact is provided.

In the present invention, in the second fluid pipe 2 made of stainless steel or the like, the second engaging portion E2 is disposed in the bulging portion 23 that is plastically deformed. Therefore, the second engaging portion E2 is expanded in diameter, and a large compressive load is applied when a separation force acts between the fluid pipes. However, according to the present invention, the first insulating ring 31 is interposed between the first engagement portion E1 and the second engagement portion E2. Therefore, the crack of the coating film of the said 2nd engaging part E2 and the 1st engaging part E1 can be prevented.

In the present invention, a thermoplastic resin or rubber can be preferably used as the resin constituting the insulating ring.
The cast iron may be, for example, ductile cast iron.

It is sectional drawing of the joint structure before the diameter expansion concerning Example 1 of this invention. It is sectional drawing of the joint structure after the diameter expansion concerning Example 1 of this invention. It is sectional drawing of the joint structure before the diameter expansion concerning Example 2 of this invention. It is sectional drawing of the joint structure after diameter expansion concerning Example 2 of this invention. It is an expansion perspective view of the whole joint shown with the digital photograph which carried out the cross section after applying a tensile load to the joint of the structure approximated to Example 1, and was image | photographed. FIG. 3 is an enlarged perspective view of a part of the joint shown by a photograph taken in a cross-section after applying a tensile load to the joint having a structure similar to that of Example 1. It is an expansion perspective view of the remainder of a joint shown in the photograph which carried out the section and impressed after applying the tensile load to the joint of the structure approximated to Example 1. FIG.

Preferably, the insertion portion 20 has a distal end portion 22.
The receiving portion 10 has a back end portion 12 in which the distal end portion 22 of the insertion portion 20 is engaged in the tube axis direction S.
A resin-made first resin is inserted between the tip portion 22 and the back end portion 12 to prevent the coating film P of the tip end portion 22 and the coating film P of the back end portion 12 from coming into direct contact with each other. Two insulating rings 32 are provided.

  A large compressive load is applied to the receiving portion 10 and the back end portion 12 when the pipe line is bent. However, even in this case, since the second insulating ring 32 prevents the coating films P of the receiving portion 10 and the back end portion 12 from coming into direct contact with each other, it is possible to prevent the coating film P from being cracked at the site.

Preferably, the receiving portion 10 includes annular protrusions 14 and 14A that are provided closer to the opening 13 of the receiving portion 10 than the seal ring SR and protrude toward the center O of the receiving portion 10. ,
The coating 14 is inserted between the protrusions 14 and 14A and the outer peripheral surface 21 of the second fluid pipe 2, and the coating film P of the protrusions 14 and 14A and the coating of the outer peripheral surface 21 of the second fluid pipe 2 are used. Resin third insulating rings 33 and 33A for preventing direct contact with the film P are provided.

A large compressive load is applied to the protrusions 14 and 14A of the first fluid pipe 1 and the outer peripheral surface 21 of the second fluid pipe 2 when the pipe line is bent. However, even in this case, since the second insulating ring 32 prevents the coating films P on the outer peripheral surface 2 of the projecting portions 14 and 14A and the second fluid pipe 2 from coming into direct contact with each other, cracks in the coating film P at such sites are prevented. Etc. can be prevented.

More preferably, the protrusion 14A is a protrusion that contacts the seal ring SR in the tube axis direction S and prevents the seal ring SR from popping out when the seal ring SR receives fluid pressure. Features.
In this case, the bulge method will suppress excessive expansion of the diameter and prevent the expanded portion from rubbing against the protrusion 14A.

Features described and / or illustrated in connection with one such embodiment or each of the following examples may be in the same or similar form in one or more other embodiments or other examples, and / or It can be utilized in combination with or instead of the features of other embodiments or examples.

The invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings, in which: However, the examples and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the present invention is defined only by the claims. In the accompanying drawings, the same part numbers in a plurality of drawings indicate the same or corresponding parts.

Example 1:
A first embodiment of the present invention will be described below with reference to FIGS. 1A and 1B show the state before the diameter expansion, and FIGS. 2A and 2B show the state after the diameter expansion.

As shown in FIG. 1, for example, a stainless steel fluid pipe insertion portion 20 constituting the second fluid pipe 2 is inserted into a metal first fluid pipe opening 10 made of ductile cast iron. ing.
The receiving part 10 of the first fluid pipe may be, for example, a well-known flexible joint mouth, or may be another well-known deformed pipe. The second fluid pipe 2 may be made of steel, and a plate flange or the like may be integrally welded to the left end portion of the drawing.

In FIG. 1B, a seal ring SR made of rubber or the like is inserted between the receiving portion 10 and the insertion portion 20, and the receiving portion 10 and the insertion portion 20 are separated by the seal ring SR. The space is sealed. The position of the seal ring SR is arranged at a position closer to the opening 13 of the receiving portion 10 than the position of an engagement means E described later.

  A resin coating film P is formed on the inner and outer peripheral surfaces of both fluid pipes 1 and 2. In particular, as can be seen from FIG. 5, a thick coating film P made of resin by powder coating is formed on the inner peripheral surface 11 of the receiving portion 10 and the outer peripheral surface 21 of the insertion portion 20, respectively.

2B, the first engaging portion E1 provided on the inner periphery of the receiving port 10 is engaged with the second engaging portion E2 on the outer periphery of the second fluid pipe 2 in the tube axial direction S. In combination, the fluid pipes 1 and 2 are prevented from separating from each other.
In the case of the present embodiment, the second engagement portion E2 is formed by cutting out the material of the second fluid pipe 2.

As shown in FIGS. 2A and 2B, the second fluid pipe 2 has a bulging portion 23 that is plastically deformed and has a diameter expanded toward the outer side R1 in the radial direction. The second engaging portion E <b> 2 is disposed in a part of the bulging portion 23.

The second engagement portion E2 may be an annular ridge, while the first engagement portion E1 may be an annular ridge that forms an annular groove 15. The first engagement portion E1 protrudes toward the center O, while the second engagement portion E2 protrudes toward the radially outward R1.

In the groove 15 of FIG. 2B, for example, a resin ring having a cross section of “concave shape” or “U shape” constituting the first insulating ring 31 is mounted. The first insulating ring 31 is formed of, for example, a thermoplastic resin, and a part of the first insulating ring 31 is interposed between the first engagement portion E1 and the second engagement portion E2, and the first engagement portion E1 The coating film P and the coating film P of the second engagement portion E2 are prevented from coming into direct contact.

In FIG. 2B, the insertion portion 20 has a distal end portion 22. On the other hand, the receiving portion 10 has a back end portion 12 in which the distal end portion 22 of the insertion portion 20 engages in the tube axis direction S.
A second insulating ring 32 is interposed between the tip portion 22 and the back end portion 12. The second insulating ring 32 is made of, for example, rubber and prevents the coating film P at the tip end portion 22 and the coating film P at the back end portion 12 from coming into direct contact.

Even if the second insulating ring 32 made of rubber is subjected to a large load generated when the first fluid pipe 1 and the second fluid pipe 2 are greatly bent from each other, it will be less likely to be damaged than the thermoplastic resin.
The second insulating ring 32 may have a “he” cross section in contact with the inner surface of the back end portion 12 of the first fluid pipe 1.

In FIG. 2B, the receiving portion 10 has, for example, two ridges 14 and 14A. These protrusions 14 and 14A are, for example, in an annular shape, are provided closer to the opening 13 of the receiving portion 10 than the seal ring SR, and protrude toward the center O of the receiving portion 10. Third insulating rings 33, 33A are interposed between the protrusions 14, 14A and the outer peripheral surface 21 of the second fluid pipe 2. These third insulating rings 33 and 33A prevent the coating film P on the inner peripheral surface of the protrusion 14 from directly contacting the coating film P on the outer peripheral surface 21 of the second fluid pipe 2.

One of the two protrusions 14 and 14A backs up (blocks) the seal ring SR when the seal ring SR is pushed by water pressure or the like.

Of the two protrusions 14 and 14A, the other protrusion 14 may not be provided as shown in FIGS. 3A to 4B.

The non-bolt joint structure of FIG. 2A is formed by expanding the diameter of the second fluid pipe 2 with a jig 5 from the state of FIG. 1A.

Jig 5;
In order to plastically deform the second fluid pipe 2 of FIG. 1B to form the bulging portion 23 of FIG. 2B, for example, a jig 5 shown in FIGS. 2A and 2B is used.
As shown in FIG. 1A, the jig 5 includes a pressing part 50, a cylinder part 51, and a slider 52. Between the cylindrical part 51 and the slider 52, the ring-shaped pressing part 50 made of, for example, urethane rubber or the like is provided. In addition, it is preferable to provide the axial length of the pressing portion 50 over the entire length of the region in which the second fluid pipe 2 is plastically deformed.

A method of forming a non-bolt joint structure;
For example, the first fluid pipe 1 and the second fluid pipe 2 may be shipped after being connected to each other in a factory, or may be connected outdoors such as a factory site. The details of the diameter expansion method are disclosed in the above-mentioned prior literature.

Next, the result of verifying the effect of providing the first insulating rings 31 to 33 having a non-bolt joint structure will be described.

As shown in FIG. 5, first, second, and third insulating rings 31, 32, and 33 are attached to the groove 15, the back end 12, and the protrusion 14, respectively. FIG. 5 assumes a case in which a separation force is generated between both fluid pipes, and after applying a tensile load to the first fluid pipe 1 and the second fluid pipe 2 (corrected for ease of viewing). It is a cross-sectional digital photograph.

From the cross-sectional photograph of FIG. 7, it can be seen that the first insulating ring 31 is crushed by the first engaging portion E1 and the second engaging portion E2. That is, it can be seen that the first insulating ring 31 protects the coating film P on the surfaces of the first engagement portion E1 and the second engagement portion E2.

In this verification, since both fluid pipes are not bent, the usefulness of the second insulating ring 32 does not appear. However, it can be easily understood that the second insulating ring 32 will protect the coating film P on the back end portion 12 and the front end portion 22 during the bending.

In FIG. 6, it can be seen that the third insulating ring 33 between the second fluid pipe 2 and the projection 14 at the receiving end protects the coating film P on the surface of the second fluid pipe 2 and the projection 14. .

On the other hand, it can be seen that the protrusion 14 that backs up the seal ring SR and the outer peripheral surface 21 of the second fluid pipe 2 are in contact with each other, and the coating films P on both surfaces are in contact with each other and are slightly damaged. The cause of this damage will be described.

As shown in FIGS. 2A and 2B, the bulging portion 23 of the insertion portion 20 is expanded in diameter by the pressing portion 50. After this diameter expansion, the seal ring SR needs to be compressed between the bulging portion 23 and the receiving portion 10. On the other hand, the surface on the opening 13 side of the seal ring SR needs to be backed up by the protrusion 14A so as not to jump out due to water pressure. Therefore, when one third insulating ring 3 </ b> A in FIG. 2B does not exist, the outer peripheral surface 21 of the bulging portion 23 subjected to basil processing approaches or contacts the protrusion 14. In this state, when the second fluid pipe 2 moves slightly in the direction of detachment from the first fluid pipe 1, the outer peripheral surface 21 of the bulging portion 23 that swells greatly in the seal ring SR is pressed against the inner peripheral surface 11 of the protrusion 14A. It is rubbed in the state. Therefore, in the non-bolt joint using the bulge method, if the third insulating ring 33A is not provided, the coating film P at this portion will be easily damaged.

On the other hand, by providing the third insulating ring 33A on the protrusion 14A, the diameter of the bulging portion 23 can be suppressed and the coating films P can be prevented from being rubbed by the third insulating ring 33A. Let's go. Therefore, it is preferable that the hardness of the resin of each insulating ring 31, 32, 33, 33A is smaller than the hardness of the coating film P made of powder.

The present invention can be used for a joint of a line that conveys fluid such as oil or gas in addition to water.

1: First fluid pipe 10: Receiving part 11: Inner peripheral surface 12: Back end part 13: Opening
14, 14A: Protruding part 2: Second fluid pipe 20: Insertion part 21: Outer peripheral surface 22: Tip part 23: Swelling part 31: First insulating ring 32: Second insulating ring 33, 33A: Third insulating ring E : Engaging means E1: first engaging portion E2: second engaging portion O: center P: coating film R1: outward S: tube axis direction SR: seal ring

Claims (4)

A fluid in which the insertion portion 20 of the second fluid tube 2 made of stainless steel or steel is inserted into the receiving portion 10 of the first fluid tube 1 made of cast iron, and the two tubes are connected to each other without using bolts. Non-bolt joint structure of pipe,
A resin-made coating film P formed on the inner peripheral surface 11 of the receiving portion 10 and the outer peripheral surface 21 of the insertion portion 20;
A rubber seal ring SR that is inserted between the receiving portion 10 and the insertion portion 20 and seals between the receiving portion 10 and the insertion portion 20;
A first engagement portion E1 provided on the inner periphery of the receiving port 10 engages with a second engagement portion E2 on the outer periphery of the second fluid pipe 2 in the tube axial direction S, so that both the fluid pipes 1 , 2 and engaging means E for preventing the two from separating from each other,
The second fluid pipe 2 has a bulging portion 23 that is plastically deformed and expanded in diameter toward the outer side R1 in the radial direction.
The second engagement portion E2 is disposed in a part of the bulge portion 23,
The coating film P of the first engagement part E1 and the coating film P of the second engagement part E2 are directly inserted between the first engagement part E1 and the second engagement part E2. A non-bolt joint structure characterized in that a resin-made first insulating ring 31 for preventing contact is provided. In claim 1,
The insertion portion 20 has a tip portion 22;
The receiving portion 10 has a back end portion 12 in which the distal end portion 22 of the insertion portion 20 is engaged in the tube axis direction S.
A resin-made first resin is inserted between the tip portion 22 and the back end portion 12 to prevent the coating film P of the tip end portion 22 and the coating film P of the back end portion 12 from coming into direct contact with each other. 2. A non-bolt joint structure in which an insulating ring 32 is provided. In claim 1 or 2,
The receiving part 10 has annular protrusions 14 and 14A which are provided closer to the opening 13 of the receiving part 10 than the seal ring SR and protrude toward the center O of the receiving part 10,
The coating 14 is inserted between the protrusions 14 and 14A and the outer peripheral surface 21 of the second fluid pipe 2, and the coating film P of the protrusions 14 and 14A and the coating of the outer peripheral surface 21 of the second fluid pipe 2 are used. A non-bolt joint structure characterized in that resin-made third insulating rings 33 and 33A for preventing direct contact with the membrane P are provided. In claim 3,
The protrusion 14A is a non-bolt that is a protrusion that contacts the seal ring SR in the tube axial direction S and prevents the seal ring SR from popping out when the seal ring SR receives fluid pressure. Joint structure.