JP7656370B2 - Pipe end corrosion protection structure in pipe joint, construction method of pipe end corrosion protection structure, and retaining ring used in pipe end corrosion protection structure - Google Patents

Description

The present invention relates to a pipe end corrosion protection structure in a pipe joint, a construction method for the pipe end corrosion protection structure, and a retaining ring used in the pipe end corrosion protection structure. More specifically, the present invention relates to a pipe end corrosion protection structure in a pipe joint that includes a joint body having a receiving portion into which a pipe is inserted, an annular packing that seals between the pipe and the joint body, a pressure ring that is connected to the joint body and presses the packing, and a corrosion protection core that is inserted into the pipe from the pipe end and covers the inner surface of the pipe end, and a construction method for the pipe end corrosion protection structure, and a retaining ring used in the pipe end corrosion protection structure.

Conventionally, as a pipe end corrosion protection structure for the above-mentioned pipe joint, for example, the one described in Patent Document 1 is known. In this pipe end corrosion protection structure, the flange portion of the corrosion protection cap is adhered to the socket portion of the joint body, and the flange portion is tightly clamped between the socket portion and the packing by screwing and tightening the pressure ring, thereby preventing the corrosion protection cap from falling off. As a result, it takes time to adhere the flange portion, which reduces workability. In addition, because the flange portion is clamped between the socket portion and the packing, the pipe joint cannot be slid relative to the existing pipe, and therefore cannot be used to repair (connect) existing pipes.

JP 2013-204737 A

In view of the above-mentioned conventional situation, the present invention aims to provide a pipe end corrosion protection structure for a pipe joint that is simple in structure yet easy to work with and can also be used to repair existing pipes, a construction method for the pipe end corrosion protection structure, and a retaining ring for use in the pipe end corrosion protection structure.

In order to achieve the above object, the pipe end corrosion protection structure in the pipe joint according to the present invention is characterized in that it comprises a joint body having a receiving portion into which a pipe is inserted, an annular packing that seals between the pipe and the joint body, a pressure ring connected to the joint body and pressing the packing, and a corrosion protection core that is inserted into the pipe from the pipe end and covers the inner peripheral surface of the pipe end, the pressure ring being a union nut that is screwed and fastened to the joint body with the packing interposed in the receiving portion, a rubber cover that is separate from the packing and has a cylindrical portion that is in close contact with the outer peripheral surface of the pipe end and a rib that protrudes from the cylindrical portion toward the center, and a retaining ring with a hook that is engaged with the outer peripheral surface of the union nut, the retaining ring being a pair of divided bodies that are fixed to the outer peripheral surface of the pipe by a fastening means facing each other, and a retaining ring that is inserted into the pipe end from the pair of divided bodies through which the fastening means is inserted and is sandwiched between the pair of divided bodies. The split body has at least a main body that runs along the outer circumferential surface of the pipe, an arm with the hook at its tip that runs along the axial direction of the pipe, and a protruding portion on which the arm is provided that protrudes outward from the end of the main body. A pair of teeth protruding toward the pipe are formed on the back surface of the main body between the end of the main body and the center of the longitudinal direction of the main body, and are provided line-symmetrically with respect to the center. The protruding portion has at least a flange portion that has a through hole through which the fastening means passes and that clamps the rubber member. When each split body is engaged with the outer circumferential surface of the union nut by the hook, and the pair of split bodies are connected by the fastening means to clamp the rubber member between the opposing flange portions, the inner diameter of the tooth tip of the teeth is larger than the outer diameter of the tubular portion of the pipe end with the rubber cover attached.

In the above configuration, the inner diameter of the receiving portion and the inner diameter of the opening of the pressure ring are larger than the outer diameter of the tubular portion of the pipe end to which the rubber cover is attached, and the inner diameter of the receiving portion is the minimum inner diameter of the fitting body, and the inner diameter of the opening is the minimum inner diameter of the pressure ring.

Here, the pipe is, for example, an internally lined steel pipe. The wall thickness of the cylindrical portion is preferably 1.0 to 1.5 mm, and the amount of expansion and contraction of the cylindrical portion in the axial direction is preferably 1.0 mm or less.

In order to achieve the above object, the feature of the construction method of the pipe end corrosion protection structure in the pipe joint according to the present invention is that, in the construction method of the pipe end corrosion protection structure in the pipe joint described in the above configuration, the rubber cover and the corrosion protection core are attached to the pipe end of the newly installed pipe, the pipe end surface of the pipe end is covered by the rib and the flange portion of the corrosion protection core, the packing is interposed in the receiving portion, the union nut is screwed onto the joint body, and each divided body is engaged with the outer peripheral surface of the union nut by the hook, and the pair of divided bodies are connected by the fastening means, and the rubber member is fastened to each of the opposing hooks. The pipe end portion, to which the rubber cover and the corrosion protection core are attached, is inserted into the joint body, which is connected to the pair of split bodies that sandwich the rubber member and the union nut, until the tip of the tubular part approaches the opening of the union nut, and the union nut is screwed and fastened to the joint body, so that the packing presses the tubular part against the outer circumferential surface of the newly installed pipe, and the pair of split bodies are fastened and fixed to the newly installed pipe by the fastening means, so that the central part approaches the newly installed pipe and the teeth bite into the newly installed pipe.

In order to achieve the above object, another feature of the method for constructing a pipe end corrosion protection structure in a pipe joint according to the present invention is that, in the method for constructing a pipe end corrosion protection structure in a pipe joint described in the above configuration, the inner diameter of the receiving portion and the inner diameter of the opening of the pressure ring are larger than the outer diameter of the tubular portion of the pipe end to which the rubber cover is attached, and the inner diameter of the receiving portion is the minimum inner diameter of the joint body, and the inner diameter of the opening is the minimum inner diameter of the pressure ring, the rubber cover and the corrosion protection core are attached to each of the pipe ends of the cut existing pipe, the pipe end surface of the pipe end is covered with the rib and the flange portion of the corrosion protection core, the packing is interposed between each receiving portion at both ends of the joint body, the union nut is screwed onto the joint body, and each divided body is engaged with the outer peripheral surface of the union nut by the hook, the pair of divided bodies are connected by the fastening means, the rubber member is clamped between the opposing flange portions, and the rubber member is clamped between the respective flange portions. The pipe end of one of the existing pipes, to which the rubber cover and the anticorrosive core are attached, is inserted into one of the sockets of the joint body, which connects the pair of split bodies and the union nut, and the joint body is moved until the pipe end of one of the existing pipes is positioned in the other socket of the joint body, the pipe end of the other of the existing pipes, to which the rubber cover and the anticorrosive core are attached, is inserted into the other socket of the joint body, and the joint body is moved until the tip of the tubular part of each pipe end, to which the rubber cover and the anticorrosive core are attached, is close to the opening of each union nut, and each union nut is screwed and fastened to the joint body, and the tubular part is pressed against the outer peripheral surface of the existing pipe by the packing, and the pair of split bodies are fastened and fixed to the existing pipe by the fastening means, so that the central part is close to the existing pipe and the teeth are bitten into the existing pipe.

In order to achieve the above object, the feature of the retaining ring used in the pipe end corrosion protection structure in the pipe joint according to the present invention is that in the retaining ring used in the pipe end corrosion protection structure in a pipe joint having a joint body having a receiving portion into which a pipe is inserted, an annular packing that seals between the pipe and the joint body, a pressing ring connected to the joint body and pressing the packing, and a corrosion protection core that is inserted into the pipe from the pipe end and covers the inner peripheral surface of the pipe end, the pressing ring is a union nut that is screwed and fastened to the joint body with the packing interposed in the receiving portion, the pipe end is fitted with a rubber cover that is separate from the packing and has a cylindrical portion that is in close contact with the outer peripheral surface of the pipe end and a rib that protrudes from the cylindrical portion toward the center, a pair of divided bodies that are fixed to the outer peripheral surface of the pipe by a fastening means facing each other, and a rubber member through which the fastening means is inserted and that is sandwiched between the pair of divided bodies, The body has at least a main body that runs along the outer circumferential surface of the pipe, a hook that engages with the outer circumferential surface of the union nut, an arm with the hook at its tip that runs along the axial direction of the pipe, and a protrusion that protrudes outward from the end of the main body and has the arm. On the back surface of the main body, a pair of teeth that protrude toward the pipe are formed between the end of the main body and the center of the longitudinal direction of the main body, and are provided line-symmetrically with respect to the center. The protrusion has at least a flange that has a through hole through which the fastening means passes and clamps the rubber member. When each divided body is engaged with the outer circumferential surface of the union nut by the hook, and the pair of divided bodies are connected by the fastening means to clamp the rubber member between the opposing flanges, the inner diameter of the tooth tip of the teeth is larger than the outer diameter of the tubular portion of the pipe end with the rubber cover attached.

The pipe end corrosion protection structure in a pipe joint and the installation method of the pipe end corrosion protection structure according to the present invention, as well as the features of the retaining ring used in the pipe end corrosion protection structure, have a simple structure yet are easy to work with, and can also be applied to the repair of existing pipes.

Other objects, configurations and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments of the invention.

FIG. 2 is a perspective view showing a pipe end corrosion protection structure in a pipe joint according to the present invention. FIG. 4 is a view taken in the pipe axial direction, showing a state before the retaining ring is fastened. FIG. 3 is a plan view of FIG. 2 . FIG. 3 is a side view of FIG. 2 . This is a cross-sectional view taken along line AA in FIG. 13 is a diagram illustrating a state in which the retaining ring and the pressing ring are engaged with each other before the pipe is inserted. FIG. FIG. 4 is a perspective view showing a first division body. FIG. 4 is a perspective view showing a second division body. FIG. FIG. 3 is a view equivalent to FIG. 2 and illustrating a state after the retaining ring has been fastened. 4 and shows a state after the retaining ring is tightened. FIG. FIG. 13 is a diagram illustrating the construction procedure for a newly installed pipe. FIG. 13 is a diagram illustrating the construction procedure for a newly installed pipe. FIG. 1 is a diagram illustrating the construction procedure for an existing pipe. FIG. 1 is a diagram illustrating the construction procedure for an existing pipe.

Next, the present invention will be described in more detail with reference to the accompanying drawings as appropriate.
1 and 5, the pipe end corrosion protection structure 1 in the pipe joint 10 according to the present invention generally comprises a joint body 2 having a socket portion 21 into which the pipe 100 is inserted, an annular packing 3 that seals between the pipe 100 and the joint body 2, a pressure ring 4 connected to the joint body 2 and pressing the packing 3, a corrosion protection core 5 inserted into the pipe from the pipe end 110 of the pipe 100 and covering the inner circumferential surface 101 of the pipe end 110, and a rubber cover 6 attached to the outer circumferential surface 102 of the pipe end 110. In this embodiment, the pipe end corrosion protection structure 1 further comprises a retaining ring 7 equipped with a hook 72 that engages with the outer circumferential surface of the pressure ring 4.

In this embodiment, as shown in FIG. 5, the pipe 100 is an internally lined steel pipe in which a lining 103 is applied to the inner peripheral surface 102 of the pipe 100, and the outer peripheral surface 101 is not covered with a lining. Examples of the lining 103 include materials such as rigid polyvinyl chloride and polyethylene. When the pipe 100 is cut, the metal pipe body 111 is exposed at the cut surface (pipe end surface 112), and corrosion progresses from the exposed metal parts, the outer peripheral surface 101 and the exposed part 113 of the pipe end surface 112. The pipe end corrosion protection structure 1 according to the present invention prevents corrosion of the pipe end 110 by covering the outer peripheral surface 101 and the pipe end surface 112 inside the joint body 2.

As shown in Figures 1 and 5, the fitting body 2 has a tapered socket portion 21 and a male thread 22 engraved on its outer circumferential surface. The inner diameter R1 of the socket portion 21 is slightly larger than the sum of the outer diameter R2 of the pipe 100 and the wall thickness t of the rubber cover 6 so that the pipe end portion 110 with the rubber cover 6 attached can be inserted.

In this embodiment, the pressure ring 4 is a union nut that is screwed and fastened to the receiving portion 21 with the packing 3 interposed therebetween. As shown in Figs. 1 and 5, this union nut 4 has a groove 41 on the outer circumferential surface in which the hook 72 of the retaining ring 7 is engaged, a female thread 42 engraved on the inner circumferential surface, and an annular flange 44 protruding from the groove 41. By screwing and fastening the union nut 4 to the receiving portion 21, the packing 3 is compressed and deformed to ensure the watertightness of the pipe joint. The inner diameter R3 of the opening 43 of the union nut 4 is also formed slightly larger than the sum of the outer diameter R2 of the pipe 100 and the wall thickness t1 of the rubber cover 6 so that the pipe end 110 with the rubber cover 6 attached can be inserted.

As shown in FIG. 5, the corrosion protection core 5 has a cylindrical portion 51 that covers the lining 103 on the inner peripheral surface 102 of the pipe end 110, and an annular flange portion 52 that protrudes outward from the cylindrical portion 51. A plurality of annular protrusions 53 are provided on the inside of the cylindrical portion 51. The cylindrical portion 51 has an outer diameter slightly larger than the inner diameter of the pipe 100 so that it fits closely against the inner peripheral surface 102 of the pipe 100. For example, a product such as that described in JP 2009-41638 A can be used as such a corrosion protection core 5.

As shown in FIG. 5, the rubber cover 6 has a cylindrical portion 61 that is in close contact with the outer circumferential surface 101 of the pipe end 110, and an annular rib 62 that protrudes from the cylindrical portion 61 toward the center. The rubber thickness t1 of the cylindrical portion 61 is approximately the same as the outer surface coating thickness of the inner and outer surface lined steel pipe, for example, 1.0 to 1.5 mm. If the rubber thickness t1 is made thin, it may break when it is attached or pressed against the pipe 100 by the union nut 4. On the other hand, if the rubber thickness t1 is made thick, the outer diameter of the pipe end 110 will be larger than the inner diameter R1 of the receiving portion 21, and it may come into contact with the teeth portion 71b described later and break, or the pipe 100 may not be able to be inserted into the fitting body 2. If the thickness t1 is 1.0 to 1.5 mm, it is easy to manufacture.

The amount of expansion and contraction of the tubular portion 61 in the axial direction X is, for example, 1.0 mm or less. In the above-mentioned Patent Document 1, as described above, the flange portion of the corrosion protection cap is bonded and fixed to the receiving portion of the joint body, and the flange portion is firmly clamped between the receiving portion and the packing by screwing and tightening the pressing ring, so that the approximately C-shaped retaining ring (pipe detachment prevention device) expands and contracts, and therefore the corrosion protection cap needs to have elasticity (for example, about 8 mm). However, since the pipe 100 in the present invention is a steel pipe and the retaining ring 7 is a pair of semicircular arc-shaped divided bodies 70a, 70b, the expansion and contraction and flexibility (flexibility) are slight. Therefore, the rubber cover 6 only needs to have the strength to press the tubular portion 61 against the outer circumferential surface 101 of the pipe end 110 at the opening 43 of the union nut 4, and the amount of expansion and contraction may be small. As shown in FIG. 11, when the retaining ring 7 is fastened and fixed by the fastening means 9, a gap is formed between the tip 72a of the hook 72 and the main body of the union nut 4, and this gap determines the amount of expansion and contraction in the axial direction X.

Here, as shown in FIG. 5, the protruding width W of the rib 62 is smaller than the wall thickness t2 of the pipe body 111, and the inner end 62a of the rib 62 is located closer to the outer surface 101 than the inner edge (inner circumferential surface 102 side) of the pipe end face 112. That is, the inner part of the pipe end face 112 does not contact the rib 62 and becomes the exposed part 113 of the pipe body 111. As described above, the cylindrical part 51 is formed so that its outer diameter is slightly larger than the inner diameter of the pipe 100, and is also provided with an annular protrusion 53 that protrudes toward the center. Therefore, if the rib 62 protrudes to the inner circumferential surface 102 or lining 103 of the pipe 100, the rib 62 will come into contact with the cylindrical part 51 or the annular protrusion 53 when it is fitted into the pipe 100. Therefore, by making the protruding width W of the rib 62 smaller than the wall thickness t2 of the pipe body 111 and forming an exposed portion 113 on the inside portion of the pipe end face 112, contact between the two can be avoided, making insertion easier and improving workability.

In this embodiment, the retaining ring 7 is made up of a pair of first and second segments 70a and 70b that face each other and are fixed to the outer circumferential surface 101 of the pipe 100 by a fastening means 9, as shown in Figures 1 to 4.

As shown in Figures 2 to 4, 6, and 7, the first divided body 70a has a main body 71 that runs along the outer circumferential surface 101, an arm 73 that runs along the axial direction X of the pipe 100 and has a hook 72 at its tip that engages with the union nut 4, and a protruding part 74 on which the arm 73 protrudes outward from the end 71a of the main body 71. The first divided body 70a is symmetrical about the center of the main body 71.

The back surface (pipe 100 side) of the main body 71 is provided with teeth 71b protruding toward the pipe 100 side near the protruding portion 74. A plurality of teeth 71b are arranged at appropriate intervals in the width direction of the main body 71 (axial direction X of the pipe 100). The teeth 71b are also arranged symmetrically with respect to the center of the main body 71.

The protrusion 74 has a flange portion 75 having a through hole 76 through which the bolt 9a of the fastening means 9 passes, and a wall portion 77 suspended from the flange portion 75. In this embodiment, the wall portion 77 is provided only on the side portion (the outer end portion in the radial direction of the pipe 100) of the flange portion 75 along the axial direction X, and no member equivalent to the wall portion 77 is provided on both ends of the flange portion 75 perpendicular to the axial direction X. As a result, as shown in FIG. 11, the compressive deformation of the rubber member 8 due to the reduction in diameter of the retaining ring 7 is induced in the axial direction X, so that the tightening torque does not become excessive and the workability does not decrease. Note that, as shown in FIG. 4, the length L of the wall portion 77 along the axial direction X is equal to the length of the rubber member 8 along the axial direction X.

As shown in FIG. 4, the hook 72 and the arm 73 are formed at the same height (thickness) H1 from the surface 75a of the flange portion 75. On the other hand, the wall portion 77 is formed at a height (thickness) H2 from the surface 75a of the flange portion 75. That is, the end 77a of the wall portion 77 facing the other divided body protrudes slightly toward the other divided body more than the end 73a of the hook 72 and the arm 73 facing the other divided body (H1<H2).

As shown in Figure 6, before the pipe 100 is inserted, the first and second halves 70a, 70b connected by the fastening means 9 are biased downward (locked) due to gravity. In the present invention, a rubber cover 61 is attached to the outer circumferential surface 101 of the pipe 100 to be inserted, so the teeth 71b are spaced apart from the outer circumferential surface 101. Therefore, if the height (thickness) H1 of the hook 72 and arm 73 is low (thin), there is a possibility that the retaining ring 7 will fall off the union nut 4. Therefore, for example, the height (thickness) H1 of the hook 72 and arm 73 is made larger than the thickness T of the flange portion 75 (T < H1 < H2). As a result, the tip 72a of the hook 72 of the first divided body 70a forms an interference portion Pi (hatched portion in the figure) that can interfere (contact) with the annular flange 44, and a part of the tip 72a of the hook 72 of the second divided body 70b also forms an interference portion Pi (hatched portion in the figure) that can interfere with the annular flange 44, preventing the retaining ring 7 from falling off. The tip 72a of the hook 72 and the inner surface 73b of the arm 73 are curved to fit the groove portion 41 of the union nut 4 and the annular flange 44.

The second segment 70b of the retaining ring 7 has the same configuration as the first segment 70a, as shown in Figures 2 to 4, 6, and 8. However, it differs from the first segment 70a in that a protrusion 78 for preventing the head of the bolt 9a from rotating is provided on the surface 75a of the flange portion 75.

The retaining ring 7 also has a rubber member 8 through which the fastening means 9 is inserted and which is clamped between the opposing flange portions 75. As shown in FIG. 9, the rubber member 8 has a substantially rectangular main body portion 81 and a through hole 82 which penetrates the main body portion 81 and through which the bolt 9a of the fastening means 9 passes. The main body portion 81 has a clamping portion 83 which protrudes outward from one side surface and is clamped between the end portion 71a of the opposing main body portion 71. As shown in FIGS. 6 and 10, by clamping the clamping portion 83 between the end portion 71a, the position is maintained between the opposing flange portions 75 when the bolt 9a is passed through, making it easier for the bolt 9a to pass through.

Next, we will explain how to install the pipe end corrosion protection structure 1 of the present invention on a newly installed pipe 100A, mainly with reference to Figures 12A and 12B.

As shown in Figure 12A, first, the rubber cover 6 is attached to the pipe end 110 of the newly installed pipe 100A, and the corrosion protection core 5 is inserted into the pipe through the opening 63 of the rubber cover 6 (STEP 1 in the figure). As described above, the protruding width W of the rib 62 is smaller (shorter) than the wall thickness t2 of the pipe body 111, so that the cylindrical portion 51 of the corrosion protection core 5 does not come into contact with the rib 62, allowing the corrosion protection core 5 to be inserted smoothly.

Next, the union nut 4 is screwed and fastened to the joint body 2 with the packing 3 interposed in the receiving portion 21, and the retaining ring 7 is engaged in the groove portion 41 of the union nut 4 with the hook 72. The retaining ring 7 is connected by the fastening means 9 with the rubber member 8 sandwiched between the flange portions 75 of the first and second halves 70a and 70b (STEP 2 in the figure). At this time, a gap S is formed between the wall portions 77 as shown in Figures 4 and 6.

Then, as shown in FIG. 12B, the pipe end 110 is inserted into the fitting body 2 to which the retaining ring 7 and union nut 4 are connected through the opening 63 and the receiving portion 21. As described above, the inner diameter R1 of the receiving portion 21 and the inner diameter R3 of the opening 43 are formed slightly larger than the sum of the outer diameter R2 of the pipe 100 and the thickness t1 of the rubber cover 6, so that the rubber cover 6 does not come into contact with the fitting body 2 or the union nut 4, and the pipe end 110 can be inserted smoothly.

2, the rubber member 8 sandwiched (compressed) between the opposing flange portions 75 prevents the first and second division bodies 70a, 70b from approaching each other, and the tooth tips of the toothed portion 71 do not come into contact with the outer surface of the rubber cover 6 (inner diameter R4 of the tooth tips > outer diameter R5 of the rubber cover 6). Therefore, there is no need to manually separate the opposing first and second division bodies 70a, 70b in order to insert the tube 100, and the tube 100 can be smoothly passed through the retaining ring 7. Furthermore, the toothed portion 71b is not provided in the center of the main body portion 71, and a gap is formed between the tube 100 and the main body portion 71.

The pipe end 110 is inserted until the tip 61b of the end 61a of the rubber cover 6 approaches the opening 43 of the union nut 4. For example, the pipe end 110 is inserted until the tip 61b is visible between the body 71 of the first and second halves 70a, 70b and the opening 43 of the union nut 4 (the gap) (STEP 3 in the figure). In this way, the tip 61b of the cylindrical portion 61 can be used as a marker for the insertion operation, eliminating the need to mark the insertion position on the outer surface of the pipe as in the past, and improving work efficiency.

Once the insertion position has been determined, the first and second sections 70a, 70b are fastened to the pipe 100 by the fastening means 9 (STEP 4 in the figure). At this time, the fastening means 9 is used to fasten until the gap S formed between the wall portions 77 disappears. It is sufficient to fasten until the tips 77a of the wall portions 77 abut against each other, making it easy to confirm that the fastening work is complete.

At this time, as shown in FIG. 10, the tightening of the tightening means 9 causes the center of the main body 71 to deform close to the pipe 100, and the teeth 71b bite into the pipe 100. This prevents the pipe 100 from coming off. Also, as shown in FIG. 11, the rubber member 8 is compressed and deformed by the flange 75, and this compression deformation is guided in the axial direction X where there is no wall.

Next, a method of installing the pipe end corrosion protection structure 1 according to the present invention on an existing pipe will be described with reference to Figures 13A and 13B. Note that the diameter reduction of the retaining ring 7 and the compressive deformation of the rubber member 8 caused by the fastening means 9 are the same as in the case of the newly installed pipe 100A.

As shown in Figure 13A, first, the existing pipe 100B is cut in two places (STEP 1 in the figure), and a rubber cover 6 is attached to the cut portion C (pipe end 110) of the existing pipe 100B, and the corrosion protection core 5 is inserted into the pipe through the opening 63 of the rubber cover 6. Similarly, the rubber cover 6 and corrosion protection core 5 are also attached to the pipe end 110 of the joining pipe 100C to which the existing pipe 100B is connected (STEP 2 in the figure). The rubber cover 6 and corrosion protection core 5 are attached to the pipe end 110 in the same way as for the new pipe 100A.

Then, as shown in FIG. 13B, the pipe end 110 of one existing pipe 100B is inserted into the joint body 2 to which the retaining ring 7 and union nut 4 are connected through the opening 63 and the socket 21. The insertion is performed until the other opening 63 and the socket 21 are positioned at the pipe end 110 (STEP 3 in the figure). Then, the pipe end 110 of the other existing pipe 100B is inserted into the pipe end 110 of the other existing pipe 100B through the other opening 63 and the socket 21. At this time, for example, the pipe end 110 is inserted until the tip 61b is visible from the gap between the main body 71 of the first and second division bodies 70a, 70b and the opening 43 of the union nut 4 (STEP 4 in the figure). Once the insertion position is determined, the first and second division bodies 70a, 70b are fastened to the pipe 100 by the fastening means 9. As described above, the rubber cover 6 is simply attached to the outer circumferential surface 101 of the pipe end 110, so that the fitting body 2 connected to the retaining ring 7 and union nut 4 can be slid in the axial direction of the existing pipe 100B as shown in FIG. 13B, making it applicable to pipe end corrosion protection of the existing pipe 100B.

Finally, other embodiment possibilities are mentioned.
In the above embodiment, the through hole 82 of the rubber member 8 is circular, but the shape of the through hole 82 may be, for example, U-shaped. However, if the through hole 82 is U-shaped, there is a risk that it may fall off from the flange portion 75 due to compression deformation. Therefore, a circular through hole 82 as in the above embodiment is preferable.

1: Pipe end corrosion protection structure, 2: Fitting body, 3: Gasket, 4: Press ring (union nut), 5: Corrosion protection core, 6: Rubber cover, 7: Retaining ring, 8: Rubber member, 9: Fastening means, 9a: Bolt, 9b: Nut, 10: Pipe fitting, 21: Socket portion, 22: Male thread, 41: Groove portion, 42: Female thread, 43: Opening, 44: Annular flange, 51: Cylindrical portion, 52: Flange portion, 53: Annular convex portion, 61: Cylindrical portion, 61a: End portion, 61b: Tip, 62: Rib, 62a: Inner end portion, 63: Opening, 70a: First division body, 70b: Second division body, 71: Main body portion, 71a: End portion, 71b: Teeth portion, 72: Hook, 72a: Tip, 73: Arm, 73a: End portion, 73b: Inner surface, 74: Protrusion portion, 75: Flange portion, 75 a: surface, 76: through hole, 77: wall, 78: ridge, 81: main body, 82: through hole, 83: clamping part, 100: pipe (inner surface lined steel pipe), 100A: new pipe, 100B: existing pipe, 100C: joint pipe, 101: outer surface, 102: inner surface, 103: lining, 110: pipe end, 111: pipe body, 112: pipe end face, 113: exposed part, C: cut part, H1: height (thickness) of hook and arm, H2: height (thickness) of wall, R1: inner diameter of socket, R2: outer diameter of pipe, R3: inner diameter of opening, R4: inner diameter of tooth tip, R5: outer diameter of rubber cover, T: thickness of flange, t1: thickness of tubular part, t2: thickness of pipe body, S: gap, Pi: interference part, X: axial direction, Y: orthogonal direction, W: protruding width

Claims (8)

A pipe end corrosion protection structure for a pipe joint comprising: a joint body having a receiving portion into which a pipe is inserted; an annular packing that seals between the pipe and the joint body; a pressure ring that is connected to the joint body and presses the packing; and a corrosion protection core that is inserted into the pipe from the pipe end and covers an inner peripheral surface of the pipe end,
The press ring is a union nut that is screwed and fastened to the joint body with the packing interposed in the receiving portion,
a rubber cover that is separate from the packing and has a cylindrical portion that is in close contact with the outer circumferential surface of the pipe end and a rib that protrudes from the cylindrical portion toward the center; and a retaining ring that has a hook that is engaged with the outer circumferential surface of the union nut.
the retaining ring includes a pair of divided bodies that are fixed to the outer peripheral surface of the pipe by a fastening means facing each other, and a rubber member through which the fastening means is inserted and which is sandwiched between the pair of divided bodies,
The divided body includes at least a main body portion that is aligned with an outer peripheral surface of the pipe, an arm that is aligned with the axial direction of the pipe and has the hook at its tip, and a protrusion that protrudes outward from an end of the main body portion and has the arm provided thereon,
A pair of teeth protruding toward the tube side are formed on the back surface of the main body between an end portion of the main body and a central portion in a longitudinal direction of the main body, and are provided symmetrically with respect to the central portion,
the protruding portion has at least a flange portion having a through hole through which the fastening means passes and for clamping the rubber member;
A pipe end corrosion protection structure in a pipe fitting, in which when each divided body is engaged with the outer peripheral surface of the union nut by the hook and the pair of divided bodies is connected by the fastening means to clamp the rubber member between the opposing flange portions, the inner diameter of the tooth tip of the tooth portion is larger than the outer diameter of the tubular portion of the pipe end with the rubber cover attached. The pipe end corrosion protection structure of claim 1, wherein the inner diameter of the receiving portion and the inner diameter of the opening of the pressure ring are larger than the outer diameter of the tubular portion of the pipe end to which the rubber cover is attached, and the inner diameter of the receiving portion is the minimum inner diameter of the fitting body, and the inner diameter of the opening is the minimum inner diameter of the pressure ring. The pipe end corrosion protection structure in a pipe joint according to claim 1 or 2, wherein the pipe is an internally lined steel pipe. A pipe end corrosion protection structure for a pipe joint according to any one of claims 1 to 3, in which the wall thickness of the cylindrical portion is 1.0 to 1.5 mm. A pipe end corrosion protection structure for a pipe joint according to any one of claims 1 to 4, in which the amount of expansion and contraction of the cylindrical portion in the axial direction is 1.0 mm or less. A method for constructing a pipe end corrosion protection structure in a pipe joint according to claim 1, comprising the steps of:
The rubber cover and the corrosion protection core are attached to the pipe end of the newly installed pipe, and the pipe end surface of the pipe end is covered by the rib and the flange portion of the corrosion protection core.
the packing is interposed in the receiving portion, the union nut is screwed onto the joint body, and each divided body is engaged with an outer peripheral surface of the union nut by the hook, the pair of divided bodies are connected by the fastening means, and the rubber member is sandwiched between the opposing flange portions;
The pipe end portion to which the rubber cover and the corrosion protection core are attached is inserted into the joint body in which the pair of divided bodies holding the rubber member therebetween and the union nut are connected, until the tip of the tubular portion approaches the opening of the union nut,
The union nut is screwed and fastened to the joint body, and the packing is used to press the cylindrical portion against the outer circumferential surface of the newly installed pipe,
A method for constructing a pipe end corrosion protection structure in a pipe fitting, in which the pair of divided bodies are fastened to the newly installed pipe by the fastening means, bringing the central portion close to the newly installed pipe and causing the teeth portion to bite into the newly installed pipe. A method for constructing a pipe end corrosion protection structure in a pipe joint according to claim 1, comprising the steps of:
an inner diameter of the receiving portion and an inner diameter of the opening of the pressure ring are larger than an outer diameter of the tubular portion of the pipe end to which the rubber cover is attached, and the inner diameter of the receiving portion is the minimum inner diameter of the joint body, and the inner diameter of the opening is the minimum inner diameter of the pressure ring,
The rubber cover and the corrosion protection core are attached to each of the cut pipe ends of the existing pipe, and the pipe end faces of the pipe ends are covered by the rib and the flange portion of the corrosion protection core.
the packing is interposed between each of the socket portions at both ends of the joint body, the union nut is screwed onto the joint body, and each divided body is engaged with an outer peripheral surface of the union nut by the hook, the pair of divided bodies are connected by the fastening means, and the rubber member is sandwiched between the opposing flange portions;
the pipe end of one of the existing pipes to which the rubber cover and the corrosion protection core are attached is inserted into one of the socket portions of the joint body which connects the pair of split bodies holding the rubber member therebetween and the union nut, and the joint body is moved until the pipe end of the one of the existing pipes is positioned in the other socket portion of the joint body;
Insert the pipe end of the other existing pipe, to which the rubber cover and the corrosion protection core are attached, into the other receiving portion of the joint body, and move the joint body until the tip of the tubular portion of each pipe end, to which the rubber cover and the corrosion protection core are attached, is close to the opening of each union nut;
The union nuts are screwed and fastened to the joint body, and the packing presses the cylindrical portion against the outer circumferential surface of the existing pipe,
A method for constructing a pipe end corrosion protection structure in a pipe joint, in which the pair of divided bodies are fastened to the existing pipe by the fastening means, bringing the central portion close to the existing pipe and causing the teeth portion to bite into the existing pipe. A retaining ring used in a pipe end corrosion protection structure in a pipe joint including a joint body having a socket portion into which a pipe is inserted, an annular packing that seals between the pipe and the joint body, a pressure ring that is connected to the joint body and presses the packing, and a corrosion protection core that is inserted into the pipe from the pipe end and covers an inner peripheral surface of the pipe end,
The press ring is a union nut that is screwed and fastened to the joint body with the packing interposed in the receiving portion,
a rubber cover is attached to the end of the tube, the rubber cover being separate from the packing and having a cylindrical portion that is in close contact with an outer circumferential surface of the end of the tube and a rib that protrudes from the cylindrical portion toward the center;
The pipe has a pair of divided bodies that are fixed to the outer circumferential surface of the pipe by a fastening means, and a rubber member through which the fastening means is inserted and which is sandwiched between the pair of divided bodies,
The divided body includes at least a main body portion that is aligned with the outer peripheral surface of the pipe, a hook that is engaged with the outer peripheral surface of the union nut, an arm that is aligned with the axial direction of the pipe and has the hook at its tip, and a protrusion that protrudes outward from an end of the main body portion and has the arm provided thereon.
A pair of teeth protruding toward the tube side are formed on the back surface of the main body between an end portion of the main body and a central portion in a longitudinal direction of the main body, and are provided symmetrically with respect to the central portion,
the protruding portion has at least a flange portion having a through hole through which the fastening means passes and for clamping the rubber member;
A retaining ring used in a pipe end corrosion protection structure in a pipe fitting, in which when each divided body is engaged with the outer peripheral surface of the union nut by the hook and the pair of divided bodies is connected by the fastening means to clamp the rubber member between the opposing flange portions, the inner diameter of the tooth tip of the tooth portion is larger than the outer diameter of the tubular portion of the pipe end with the rubber cover attached.

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