Valve installation method for existing pipes

Abstract

To efficiently implement a pipe cutting process while promoting the size reduction and weight reduction of drilling equipment in a state that a construction failure is suppressed.SOLUTION: In a valve installation method of an existing pipe having a pipe cutting process for cutting and separating a valve body insertion region of the existing pipe 1, the pipe cutting process comprises: a first pipe cutting process for cutting the pipe in a state that a drilling region H1 of a hole saw exceeds a center plane Y to the other side by the cutting-rotation of the hole saw in a first drilling center position P1 which is decentered to one side in a pipe traverse direction with respect to the center plane Y which passes a pipe axial core X of the existing pipe 1, and a drilling opening width W1 of the existing pipe 1 at one side end reaches a valve insertion setting width; and a second pipe cutting process for cutting the pipe in a state that a drilling region H2 of the hole saw exceeds the center plane Y to one side by the cutting-rotation of the hole saw in a second drilling center position P2 which is decentered to the other side with respect to the center plane Y, and a drilling opening width W2 of the existing pipe 1 at the other side reaches the valve insertion setting width.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a valve installation method for an existing pipe, comprising: a valve box exterior installation process for exteriorly installing a valve box in a valve installation area of ​​an existing pipe; a cutting device installation process for installing, on the valve box side, a cutting device having a hole saw that cuts and separates the valve body insertion portion of the existing pipe; a pipe cutting process for cutting and separating the valve body insertion portion of the existing pipe in an uninterrupted flow state by cutting rotation of the hole saw; a cutting device removal process for removing the cutting device from the valve box side; and a valve body installation process for installing a valve body on the valve box. [Background technology]

[0002] Proposed methods for installing valves on existing pipes include one that uses a hole saw with a blade diameter larger than the outer diameter of the existing pipe, as shown in Patent Document 1, and one that uses a hole saw with a blade diameter smaller than the radius of the existing pipe, as shown in Patent Document 2.

[0003] In the valve installation method shown in Patent Document 1, in the pipe cutting process, the rotation axis of the hole saw is placed on a central plane (vertical plane) that passes through the pipe axis of the existing pipe. By rotating the hole saw at the drilling center position on the central plane, the existing pipe is cut and separated in a state where the drilling opening width in the pipe axis direction on the pipe circumferential surface on both sides in the pipe transverse direction becomes the valve insertion set width.

[0004] The pipe cutting process of the valve installation method shown in Patent Document 2 includes a first pipe cutting process, in which a hole saw is rotated at a first drilling center position offset to one side in the pipe transverse direction with respect to a central plane passing through the pipe axis of the existing pipe, so that the drilling area of ​​the hole saw is offset to one side in the pipe transverse direction from the central plane, and the drilling opening width in the pipe axial direction on the pipe peripheral surface of one end of the existing pipe in the pipe transverse direction becomes a valve insertion set width; a second pipe cutting process in which the hole saw is rotated at a second drilling center position offset to the other side in the pipe transverse direction with respect to a central plane passing through the pipe axis of the existing pipe, so that the drilling area of ​​the hole saw is offset to the other side in the pipe transverse direction from the central plane of the existing pipe, and the drilling opening width in the pipe axis direction on the pipe peripheral surface of the other end of the existing pipe in the pipe transverse direction becomes a valve insertion set width; and a third pipe cutting process for cutting and separating the existing pipe by rotating a hole saw at the center position of a third drilling on a central plane passing through the pipe axis of the existing pipe, while the existing pipe is connected to the first drilling and the second drilling, and while the intermediate width of the drilling in the pipe axis direction at each connecting point becomes the valve insertion set width. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4503036 [Patent Document 2] Patent No. 4086838 Summary of the Invention [Problem to be solved by the invention]

[0006] In the valve installation method shown in Patent Document 1, a hole saw with a blade diameter larger than the outer diameter of the existing pipe is used, so the pipe cutting process can be completed with a single drilling operation. However, because the cutting area of ​​the existing pipe is large and the driving torque of the hole saw during cutting is large, there are disadvantages in that the driving unit of the cutting device, the housing, and other drilling equipment become large and heavy.

[0007] The valve installation method shown in Patent Document 2 uses a hole saw with a blade diameter smaller than the radius of the existing pipe, so the cutting area of ​​the existing pipe is small and the driving torque of the hole saw during cutting is also small, making it possible to reduce the size and weight of the drilling equipment. On the other hand, the pipe cutting process requires three drilling operations and the hole saw drilling position must be changed to three positions across the pipe, so the pipe cutting process takes a lot of work time. In addition, the hole saw is equipped with a center drill, but when the tip of the center drill comes into contact with the wall of the existing pipe, the tip of the center drill tends to shift in the circumferential direction along the wall of the pipe. This can cause the center drill to shift in position during the three drilling steps, which can lead to poor construction.

[0008] In view of this situation, the main object of the present invention is to provide a valve installation method for existing pipes that can efficiently perform the pipe cutting process while reducing the size and weight of drilling equipment and suppressing construction defects. [Means for solving the problem]

[0009] A first characteristic configuration of the present invention is a method for installing a valve on an existing pipe, the method comprising: a valve box exterior installation step of exteriorizing a valve box on a valve installation area of ​​an existing pipe; a cutting device installation step of installing a cutting device having a hole saw for cutting and separating a valve body insertion portion of the existing pipe on the valve box side; a pipe cutting step of cutting and separating a valve body insertion portion of the existing pipe in an uninterrupted flow state by cutting rotation of the hole saw; a cutting device removal step of removing the cutting device from the valve box side; and a valve body installation step of installing a valve body on the valve box, In the cutting device installation step, the hole saw having a blade diameter larger than the radius of the existing pipe is attached to the cutting device, the pipe cutting step includes a first pipe cutting step of cutting and separating the existing pipe in a state where a drilling area of ​​the hole saw extends beyond the central plane to the other side in the pipe transverse direction and a drilling opening width in the pipe axial direction on a pipe peripheral surface at one end of the existing pipe in the pipe transverse direction becomes a valve insertion set width by cutting and rotating the hole saw at a first drilling center position offset to one side in the pipe transverse direction with respect to a central plane passing through the pipe axis of the existing pipe; and a second pipe cutting process for cutting and separating the existing pipe in a state in which the drilling area of ​​the hole saw extends beyond the central plane of the existing pipe to one side in the pipe transverse direction and the drilling opening width in the pipe axial direction on the pipe circumferential surface of the other end of the existing pipe in the pipe transverse direction becomes a valve insertion set width by cutting and rotating the hole saw at a second drilling center position that is offset to the other side in the pipe transverse direction with respect to the central plane passing through the pipe axis of the existing pipe.

[0010] According to this configuration, a hole saw with a blade diameter larger than the radius of the existing pipe is used to perform two pipe cutting operations: a first pipe cutting process at a first drilling center position offset to one side in the pipe transverse direction with respect to a central plane passing through the pipe axis of the existing pipe, and a second pipe cutting process at a second drilling center position offset to the other side in the pipe transverse direction with respect to a central plane passing through the pipe axis of the existing pipe. In the first pipe cutting process, the cutting rotation of the hole saw at the first drilling center position offset to one side in the pipe transverse direction from the central plane causes the drilling area of ​​the hole saw to extend beyond the central plane to the other side in the pipe transverse direction, and the existing pipe can be cut in a state in which the drilling opening width in the pipe axial direction at the pipe circumferential surface of one side end of the existing pipe in the pipe transverse direction becomes the valve insertion set width. In the next second pipe cutting step, the hole saw rotates at a second drilling center position offset to the other side in the pipe transverse direction from the center plane, causing the drilling area of ​​the hole saw to extend beyond the center plane of the existing pipe to one side in the pipe transverse direction, thereby forming a connection in the pipe transverse direction to the drilled hole formed in the first pipe cutting step. Furthermore, the existing pipe can be cut and separated in a state where the drilling opening width in the pipe axial direction on the pipe circumferential surface at the other end of the existing pipe in the pipe transverse direction becomes the valve insertion setting width. As a result, compared to a single drilling operation using a hole saw with a blade diameter larger than the outer diameter of the existing pipe, the cutting area of ​​the existing pipe is smaller and the driving torque of the hole saw during cutting is also smaller, making it possible to make the drilling equipment smaller and lighter. In addition, compared to three drilling steps using a hole saw with a blade diameter smaller than the radius of the existing pipe, the cutting process can be carried out more efficiently and with fewer construction defects. In addition, because a hole saw with a blade diameter larger than the radius of the existing pipe is used, the drilling opening width at both ends of the existing pipe in the pipe transverse direction can be set to any valve insertion setting width corresponding to the insertion width of the valve body in the pipe axial direction. This allows for a wider range of valve insertion setting width settings compared to three drilling operations using a hole saw with a blade diameter smaller than the radius of the existing pipe.

[0011] A second characteristic configuration of the present invention is that the blade diameter of the hole saw is set to be larger than the radius of the existing pipe and smaller than the outer diameter of the existing pipe.

[0012] According to this configuration, the maximum blade diameter of the hole saw is set smaller than the outer diameter of the existing pipe, so that the drilling equipment can be made smaller and lighter while expanding the setting range of the valve insertion setting width.

[0013] The third characteristic configuration of the present invention is that the ratio of the valve insertion setting width, which is the drilling opening width at both ends of the existing pipe in the pipe cross-sectional direction, to the blade diameter of the hole saw, which is the numerator, is set to 1.1 to 1.5.

[0014] According to this configuration, in two drilling operations using a hole saw with a blade diameter larger than the radius of the existing pipe, the ratio of the valve insertion setting width as the denominator and the hole saw blade diameter as the numerator is set to 1.1 to 1.5, so that the setting range of the valve insertion setting width can be expanded while the drilling equipment can be made smaller and lighter.

[0015] A fourth characteristic configuration of the present invention is that the central width of drilling in the pipe axial direction between two intersections where the rotational trajectory of the hole saw at the first drilling center position and the rotational trajectory of the hole saw at the second drilling center position intersect is set to be the same or approximately the same as the drilling opening width at both side ends in the pipe transverse direction.

[0016] With this configuration, the cutting area of ​​the existing pipe is smaller and the driving torque of the hole saw during cutting is also smaller compared to when the central drilling width in the pipe axis direction between the intersection points of the hole saw's rotation trajectories at the first drilling center position and the second drilling center position is set larger than the drilling opening width at both side ends of the existing pipe in the pipe transverse direction, thereby making it possible to make the drilling equipment smaller and lighter.

[0017] A fifth characteristic configuration of the present invention is that in the cutting device installation process, a position change attachment that can change the installation position of the cutting device relative to the work on-off valve in the pipe transverse direction is detachably provided between the work on-off valve joined to the valve body mounting portion of the valve box, and in the pipe cutting process, by replacing the position change attachment with respect to the work on-off valve, the cutting device is configured to be freely changed between a first installation position in which the rotation axis of the hole saw corresponds to the first drilling center position, and a second installation position in which the rotation axis of the hole saw corresponds to the second drilling center position.

[0018] According to this configuration, by replacing the position-changing attachment with respect to the work on-off valve, the rotation axis of the hole saw can be changed between a first mounting position corresponding to the first drilling center position and a second mounting position corresponding to the second drilling center position. Therefore, there is no need to prepare two types of attachments, one corresponding to the first drilling center position and one corresponding to the second drilling center position, and the number of drilling equipment can be reduced.

[0019] A sixth characteristic configuration of the present invention is that in the cutting device installation process, a work valve attachment is provided between the valve body mounting portion of the valve box and the work on-off valve on the cutting device side, the work valve attachment having a first flange that can be flange-joined to the valve body mounting portion and a second flange that can be flange-joined to the work on-off valve.

[0020] According to this configuration, by performing two drilling operations using a hole saw with a blade diameter larger than the radius of the existing pipe, for example, the flange of the valve body mounting part of the valve body may be formed into a rectangular ring shape. In this case, by using a work valve attachment having a first flange that can be flange-connected to the valve body mounting part and a second flange that can be flange-connected to the work on-off valve, even a general-purpose work on-off valve with a ring-shaped flange can be used. Therefore, there is no need to modify the flange of the work on-off valve to a shape that can be flange-connected to the valve body mounting part of the valve body, and the cost of drilling equipment can be reduced. [Brief description of the drawings]

[0021] [Figure 1] A front view of the valve box being attached to the existing pipe, showing the valve installation method of the present invention. [Diagram 2] Plan view of valve body when installed [Diagram 3] Side view of valve box installed [Figure 4] Vertical cross-sectional front view when valve box is installed [Diagram 5] Cross-sectional side view when valve box is installed [Figure 6] Partial cross-sectional view of the valve body with the work valve attachment and work on-off valve attached [Figure 7] Cross-sectional side view of the first pipe cutting process before drilling begins [Figure 8] Cross-sectional side view of the first tube cutting process at the drilling start position [Figure 9] Cross-sectional side view at the end of drilling in the first tube cutting process [Figure 10] A cross-sectional side view of the hole saw returning to the storage space after cutting [Figure 11] Plan view of the existing pipe after the first pipe cutting process is completed [Figure 12] Cross-sectional side view at the end of drilling in the second tube cutting process [Figure 13] FIG. 10 is an explanatory diagram of the first embodiment when the second tube cutting process is completed. [Figure 14] The valve body installation process shows the cutting device removal process and the valve body installation process. [Figure 15] Front view of the valve body installation process completed [Figure 16] FIG. 1 is an explanatory diagram showing the flow passage blocking state and the flow passage opening state of a valve body attached to an inner valve box. [Figure 17] 2nd to 4th embodiments [Figure 18] FIG. 5 is an explanatory diagram of the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. In this embodiment, a valve installation method for an existing pipe is described in which a butterfly valve 2, which is an example of a valve, is installed in a valve installation position of an existing water pipe 1, which is an example of an existing pipe, without interrupting water supply (without interrupting flow). This valve installation method for an existing pipe includes the following main steps: a valve box exterior installation step for exteriorly installing a valve box 20 of a butterfly valve 2 on a valve installation area of ​​an existing water pipe 1 as shown in Figs. 1 to 5; a cutting device installation step for installing a cutting device 4 having a work opening / closing valve 3 and a hole saw 40 for cutting and separating a valve body insertion portion of an existing water pipe 1 on the valve box 20 side as shown in Figs. 6 and 7; a pipe cutting step for cutting and separating a valve body insertion portion of an existing water pipe 1 under an uninterrupted flow condition by cutting rotation of the hole saw 40 as shown in Figs. 8 to 13; a cutting device removal step for removing the cutting device 4 from the valve box 20 side as shown in Fig. 14; and a valve body installation step for attaching a valve body 24 of a butterfly valve 2 to a valve box 20 as shown in Figs. 14 to 16.

[0023] As shown in Figs. 14 to 16, the butterfly valve 2 used in the valve installation method for an existing pipe has a valve box 20 that is fixed in a watertight state to the outer circumferential surface of the valve installation area of ​​an existing water pipe 1, an inner valve box 23 that serves as a valve body holding frame that seals the valve body insertion port 22 of a cylindrical valve body mounting portion 21 formed on the upper side of the valve box 20 and can block the valve body mounting space inside the valve box 20 in a flow path crossing posture, a valve body 24 that opens and closes a flow path port 23a that is concentric with the pipe axis center X and is formed through the valve body holding portion 23A of the inner valve box 23, and a valve shaft operating mechanism 25 that rotates the valve shaft 24A of the valve body 24 around a vertical axis perpendicular to the pipe axis center X.

[0024] 1 to 5, the valve box 20 has a lower valve box portion 20A that opens upward and covers from below the outer circumferential surface of the valve installation area of ​​the existing water pipe 1, and an upper valve box portion 20B that opens downward and covers from above the outer circumferential surface of the valve installation area of ​​the existing water pipe 1. The lower valve box portion 20A and the upper valve box portion 20B are divided into two parts by a horizontal plane that passes through the pipe axis X of the existing water pipe 1, and are fixed by tightening bolts and nuts 26 with the divided mating surfaces 20a joined together.

[0025] As shown in Figures 14 to 16, the inner valve box 23 includes a valve cover portion 23B that seals the valve disc insertion port 22 of the valve disc mounting portion 21 of the valve box 20, and a valve disc holding portion 23A that is integrally formed in a T-shape on the lower surface of the valve cover portion 23B. The valve cover portion 23B is fixedly connected from above and below to a valve box flange 21A formed on the upper end of the valve disc mounting portion 21 of the valve box 20 with bolts and nuts (not shown). For this reason, an O-ring 27 is provided on the upper surface of the valve box flange 21A of the valve disc mounting portion 21 to seal between the flange joint surface of the valve cover portion 23B and the valve cover portion 23B when the bolts and nuts are tightened, as shown in Figure 14. 14 and 16, an elastic packing 28 is attached to the outer peripheral side surface of the valve disc holding portion 23A of the inner valve box 23, which seals between the inner surfaces (valve seat surfaces) of a pair of side wall portions 20b and the inner surface (valve seat surface) of the bottom wall portion 20c that face each other in the pipe cross direction of the valve box 20. When the valve cover portion 23B of the inner valve box 23 is fastened to the valve box flange 21A of the valve disc mounting portion 21 of the valve box 20, this elastic packing 28 is compressed to a watertight state.

[0026] In particular, in the pipe cutting process of the present invention, as shown in Fig. 8 to Fig. 13, a hole saw 40 with a blade diameter (blade tip diameter) D1 set to be larger than the radius of the existing water pipe 1 and smaller than the outer diameter of the existing water pipe 1 is used to drill holes at two positions in the transverse direction of the existing water pipe 1. Therefore, the valve body mounting portion 21 of the valve box 20 is configured to be rectangular in plan view as shown in Fig. 2. Accordingly, the contour shape of the valve cover portion 23B of the inner valve box 23 is also configured to be rectangular in plan view.

[0027] As a method for fixing the valve cover portion 23B of the inner valve box 23 in this form to the valve body mounting portion 21 of the valve box 20, for example, a fixing method is considered in which the valve cover portion 23B of the inner valve box 23 is inserted and arranged in the valve body mounting portion 21 of the valve box 20, and the inner valve box 23 is pressed and fixed to the inner bottom surface side of the valve box 20 by a plurality of bolts screwed horizontally from the outer surface of the valve body mounting portion 21 of the valve box 20. However, with this fixing method, there is a concern about the watertightness of the inner valve box 23, which is rectangular in plan view. Therefore, in this embodiment, as described above, a fixing method is adopted in which the valve box flange 21A of the valve body mounting portion 21 of the valve box 20 and the valve cover portion 23B of the inner valve box 23 are joined from above and below and fixed watertightly with bolts and nuts, so that excellent watertightness can be ensured even for the inner valve box 23, which is rectangular in plan view.

[0028] As shown in Figs. 1 to 5, a two-piece pressure ring 30 is fastened to each of the connecting flanges 29A formed at the ends of the pipe holding parts 29 on both sides of the pipe axis X direction of the valve box 20 by a T-bolt and a nut 32. The pressure ring 30 compresses a third elastic packing 31 interposed between the tapered inner peripheral surface of the pipe holding part 29 and the outer peripheral surface of the existing water pipe 1 in the pipe axis direction to a watertight state.

[0029] Next, the method for installing valves on existing pipes will be described in detail. [1] Valve box exterior process As shown in Fig. 1 to Fig. 5, the lower valve box part 20A and the upper valve box part 20B of the valve box 20 are fitted onto the outer circumferential surface of the valve installation area of ​​the existing water pipe 1. As shown in Fig. 5, the lower valve box part 20A and the upper valve box part 20B are fastened and fixed with bolts and nuts 26 in a state where the divided mating surfaces 20a passing through the pipe axis X of the existing water pipe 1 are joined together. Thereafter, the divided mating surfaces 20a of the lower valve box part 20A and the upper valve box part 20B are integrally joined by welding in a watertight state. As shown in Figures 1 to 5, a two-piece pressure ring 30 that is fitted to the existing water pipe 1 is fastened to each of the connecting flanges 29A formed at the ends of the pipe holding parts 29 on both sides in the pipe axis X direction of the valve box 20 by a T-bolt and a nut 32. By fastening and fastening the pressure ring 30, as shown in Figure 4, the third elastic packing 31 that is interposed between the tapered inner peripheral surface of the pipe holding part 29 and the outer peripheral surface of the existing water pipe 1 is compressed to a watertight state.

[0030] [2] Cutting device installation process As shown in Figures 6 and 7, a cylindrical working valve attachment 5, through which the hole saw 40 of the cutting device 4 and the inner valve box 23 can pass, is flange-joined to the valve box flange 21A of the valve disc mounting part 21 of the valve box 20. A first flange 5A is provided at the lower end of this working valve attachment 5, which can be fastened to the valve box flange 21A of the valve disc mounting part 21 with bolts and nuts 51. As shown in Figure 2, since the valve box flange 21A of the valve disc mounting part 21 is annular rectangular, the shape of the first flange 5A is also configured to be annular rectangular. 6, the upper end of the work valve attachment 5 is provided with a second flange 5B that can be fastened to a lower flange 3B formed on the lower end of the work valve case 3A of the work on-off valve 3 with bolts and nuts 52. In this embodiment, a general-purpose work on-off valve 3 in which the lower flange 3B is formed in an annular circular shape is used, and therefore the second flange 5B is also formed in an annular circular shape (not shown) corresponding to the lower flange 3B of the work on-off valve 3. Therefore, there is no need to modify the lower flange 3B of the operation on-off valve 3 into a form that allows flange joining to the valve body mounting portion 21 of the valve box 20, and the cost of drilling equipment can be reduced. In addition, as shown in Figures 4, 5, 6 and 8, an O-ring 35 is provided on the upper surface of the valve body flange 21A of the valve body mounting portion 21 to seal the joint surface with the first flange 5A of the working valve attachment 5 when the bolts and nuts 51 are tightened.

[0031] 6, a bolt operation space 53 is formed between the opposing surfaces of the first flange 5A and the second flange 5B of the working valve attachment 5 in the vertical direction, for inserting and screwing the bolts that fasten the first flange 5A and the valve box flange 21A from above. Therefore, as in the case of directly fastening the lower flange 3B of the working on-off valve 3 to the valve box flange 21A of the valve box 20, it is not necessary to secure a bolt operation space between the opposing surfaces of the outer circumferential surface of the pipe holding portion 29 of the valve box 20 and the valve box flange 21A for inserting and screwing the fastening bolts from below. This makes it possible to reduce the height dimension from the position corresponding to the pipe axis X of the valve box 20 to the valve box flange 21A.

[0032] 6 and 7, a cutting casing 42 of the cutting device 4 is attached to an upper flange 3C formed on the upper end of the work valve case 3A via a position changing attachment 6 that can change the mounting position of the cutting device 4 in the pipe transverse direction relative to the work on-off valve 3, and a drilling case 41. The position changing attachment 6 and the drilling case 41 have an internal space large enough to allow the hole saw 40 to move up and down.

[0033] The pipe cutting process of the present invention, which will be described later, includes a first pipe cutting process in which a hole saw 40 is rotated at a first drilling center position P1 that is offset to one side (the right side in FIG. 8) in the pipe cross direction with respect to a vertical center plane Y that passes through the pipe axis X of the existing water pipe 1, as shown in FIG. 8 to FIG. 11 ; As shown in Figures 12 and 13, the method includes a second pipe cutting process in which the hole saw 40 performs cutting rotation at a second drilling center position P2 that is offset to the other side in the pipe transverse direction (left side in Figure 12) with respect to a vertical center plane Y passing through the pipe axis X of the existing water pipe 1. In the first pipe cutting step, as shown in Fig. 8 to Fig. 11, a first drilling region (first drilling area in plan view) H1 of the hole saw 40 extends beyond the center plane Y to the other side in the pipe cross-sectional direction (left side in Fig. 8). Also, as shown in Fig. 11, the existing water pipe 1 is cut in a state in which a first drilling opening width W1 in the pipe axis X direction on the pipe circumferential surface at one end of the existing water pipe 1 in the pipe cross-sectional direction becomes a valve insertion set width. In the second pipe cutting step, as shown in Figures 12 and 13, the second drilling region (second drilling area in plan view) H2 of the hole saw 40 extends beyond the central plane Y of the existing water pipe 1 to one side in the pipe cross direction (the right side in Figure 12). Also, as shown in Figure 13, the existing water pipe 1 is cut and separated in a state in which the second drilling opening width W2 in the pipe axis X direction on the pipe circumferential surface at the other end of the existing water pipe 1 in the pipe cross direction becomes the valve insertion set width.

[0034] Therefore, as shown in Fig. 7, the position change attachment 6 is configured by integrating a large-diameter main body case part 61 whose up-down center line is located on the vertical center plane Y and a small-diameter eccentric case part 62 whose up-down center line can be selectively located on the first drilling center position P1 and the second drilling center position P2. A lower flange 61A is provided at the lower end of the main body case part 61, which is fastened to the upper flange 3C of the work valve case 3A with bolts and nuts 63. An upper flange 62A is provided at the upper end of the eccentric case part 62, which is fastened to the lower flange 41A of the drilling work case 41 with bolts and nuts 64.

[0035] Then, in the first pipe cutting process, the position changing attachment 6 is flange-joined to the work on-off valve 3 in an orientation in which the vertical center line of the eccentric case part 62 is located on the first drilling center position P1, as shown in Figures 7 and 8. In the second pipe cutting process, the position changing attachment 6 is flange-joined to the work on-off valve 3 in an orientation in which the vertical center line of the eccentric case part 62 is located on the second drilling center position P2, as shown in Figure 12. As described above, by rotating the position-changing attachment 6 180 degrees and replacing it with respect to the work on-off valve 3, the rotation axis of the hole saw 40 can be changed to a first mounting position corresponding to the first drilling center position P1, and a second mounting position corresponding to the second drilling center position P2. Therefore, it is not necessary to prepare two types of attachments, one corresponding to the first drilling center position P1 and the other corresponding to the second drilling center position P2, and the number of drilling equipment can be reduced.

[0036] 7, the internal space of the position-changing attachment 6 and the internal space of the drilling case 41 are configured as a storage space 43 for storing the hole saw 40 of the cutting device 4 when the work on-off valve 3 is in a closed state. An upper flange 41B is provided at the upper end of the drilling case 41, which is fastened to a connecting flange 42A at the lower end of the cutting casing 42 with bolts and nuts 65.

[0037] The cutting device 4 is driven by a prime mover such as an electric motor or an engine to apply a driving torque and a moving force in the direction of the drilling axis to a driving shaft 44 supported by a cutting casing 42. As shown in Figures 8 to 13, a cylindrical hole saw 40 connected to the tip of the driving shaft 44 has a blade diameter (blade tip diameter) D1 that is larger than the radius of the existing water pipe 1 and smaller than the outer diameter of the existing water pipe 1. The length of the hole saw 40 in the direction of the rotation axis is set to be larger than the outer diameter of the existing water pipe 1.

[0038] In addition, a center drill 45 is provided at the center of the inner bottom of the hole saw 40, which extends outward from the tip of the hole saw 40 along the rotation axis, as shown in Figs. 7 to 10. The projection of the center drill 45 is set to a projection dimension that allows the hole saw 40 to penetrate the wall of the existing water pipe 1 and position the cut when the tip of the hole saw 40 comes into contact with the outer circumferential surface of the existing water pipe 1 and starts cutting, as shown in Fig. 8. Two sets of freely rising and falling locking bodies 46 are provided at two positions spaced apart in the rotation axis direction of the center drill 45 to prevent the cutting piece 1A that has entered the hole saw 40 from falling out. Each locking body 46 is stored in an unlocked position when penetrating the wall of the existing water pipe 1, and protrudes into an engaged position by centrifugal force after passing through the wall. Furthermore, when the hole saw 40 is advanced to the drilling end position, the two sets of locking bodies 46 are arranged in an locking position on the inner and outer surfaces of the upper pipe wall of the section 1A.

[0039] [3] Pipe cutting process Among Figs. 8 to 13 which explain the pipe cutting process, cross-sectional hatching of drilling equipment is omitted in Figs. 7, 9, 10 and 12. [3-1] First pipe cutting process In the initial setting of the first pipe cutting process shown in Fig. 7, the position changing attachment 6 is flange-joined to the work on-off valve 3 in an orientation in which the vertical center line of the eccentric case part 62 is located on the first drilling center position P1 (on the right side in Fig. 7). In this state, as shown in Fig. 8, the work valve body 3D of the work on-off valve 3 is opened, and the hole saw 40 and center drill 45 of the cutting device 4 are fed downward while being driven and rotated. As shown in Fig. 8, the center drill 45 of the hole saw 40 drills a first drilling center position P1 that is offset to one side in the pipe transverse direction (the right side in Fig. 8) with respect to a vertical center plane Y that passes through the pipe axis X of the existing water pipe 1. The hole saw 40 rotates around the center drill 45 that drills the first drilling center position P1, and drills a hole in the pipe wall of the existing water pipe 1.

[0040] 11, the first drilling region (first drilling area in plan view) H1 of the hole saw 40 is set to a region that goes beyond the center plane Y of the existing water pipe 1 to one side in the pipe cross direction (lower side in FIG. 11) and where the first drilling opening width W1 in the pipe axis center X direction on the pipe circumferential surface of the other end in the pipe cross direction of the existing water pipe 1 is the valve insertion set width. Also, the drilling center width W3 in the pipe axis center X direction between two intersections where the first rotary cutting path (first drilling inner circumferential surface) R1 of the hole saw 40 at the first drilling center position P1 and the center plane Y of the existing water pipe 1 intersect is set to be the same or approximately the same as the first drilling opening width (valve insertion set width) W1 of the other end in the pipe cross direction of the existing water pipe 1.

[0041] As shown in FIG. 9, when the hole saw 40 drilling at the first drilling center position P1 is sent to the drilling end position, the section 1A on one side cut and separated from the existing water pipe 1 is in a state of being inserted into the hole saw 40. In this state, about half of the cross-sectional area of ​​the flow passage in the existing water pipe 1 is secured compared to the case where the hole saw is cut with a hole saw larger than the outer diameter of the existing water pipe 1. Therefore, the flow of water in the existing water pipe 1 is less likely to be obstructed. The upper pipe wall of the section 1A in the hole saw 40 is retained and held by two retaining bodies 46 of the center drill 45. Therefore, as shown in FIG. 10, even if the hole saw 40 at the cutting end position is pulled up to the storage space 43 formed by the internal space of the position changing attachment 6 and the internal space of the drilling work case 41, the section 1A in the hole saw 40 can be collected without falling off.

[0042] [3-2]Second pipe cutting process 10, when the hole saw 40 has returned to a predetermined storage position within the storage space 43, the work valve body 3D of the work on-off valve 3 is closed. After that, the upper flange 3C of the work valve case 3A and the lower flange 61A of the position changing attachment 6 are released from the fastening with the bolts and nuts 63. The drilling equipment in which the released position changing attachment 6, the drilling case 41, and the cutting device 4 are assembled together is hoisted and transported by a crane or the like to a section recovery work site, and the section 1A within the hole saw 40 is removed.

[0043] Thereafter, the position changing attachment 6 of the drilling equipment is suspended and transported to a flange joining position corresponding to the working valve case 3A. At this time, as shown in Fig. 12, the position changing attachment 6 is flange-joined to the upper flange 3C of the working on-off valve 3 in an orientation in which the vertical center line of the eccentric case part 62 is located on the second drilling center position P2. In other words, by rotating the position changing attachment 6 180 degrees relative to the working on-off valve 3, the rotation axis of the hole saw 40 is changed from the first mounting position for the first pipe cutting process corresponding to the first drilling center position P1 to the second mounting position for the second pipe cutting process corresponding to the second drilling center position P2.

[0044] In this state, as shown in FIG. 12, the work valve body 3D of the work on-off valve 3 is opened, and the hole saw 40 of the cutting device 4 is fed downward while being driven to rotate. The center drill 45 of the hole saw 40 drills a second drilling center position P2 that is offset to the other side in the pipe transverse direction (left side in FIG. 12 ) with respect to a central plane Y that passes through the pipe axis X of the existing water pipe 1. The hole saw 40 rotates around the center drill 45 that drills the second drilling center position P2, and drills a hole in the pipe wall of the existing water pipe 1.

[0045] As shown in Fig. 13, the second drilling area H2 of the hole saw 40 (second drilling area in plan view) is set to an area beyond the center plane Y of the existing water pipe 1 to the other side in the pipe cross-sectional direction (upper side in Fig. 13) and in which the second drilling opening width W2 in the pipe axis center X direction on the pipe circumferential surface of one end of the existing water pipe 1 in the pipe cross-sectional direction is the valve insertion set width. In addition, the drilling center width W3 in the pipe axis center X direction between two intersections where the first rotary cutting trajectory (first drilling inner circumferential surface) R1 of the hole saw 40 at the first drilling center position P1 and the second rotary cutting trajectory (second drilling inner circumferential surface) R2 of the hole saw 40 at the second drilling center position P2 intersect is set to be the same or approximately the same as the first drilling opening width W1 and the second drilling opening width W2 at both ends of the existing water pipe 1 in the pipe cross-sectional direction.

[0046] As described above, in this embodiment, a hole saw 40 having a blade diameter (blade tip diameter) D1 that is larger than the radius of the existing water pipe 1 and smaller than the outer diameter of the existing water pipe 1 is used to perform two pipe cutting operations: a first pipe cutting process at a first drilling center position P1 that is offset to one side in the pipe transverse direction with respect to a vertical center plane Y that passes through the pipe axis center X of the existing water pipe 1, and a second pipe cutting process at a second drilling center position P2 that is offset to the other side in the pipe transverse direction with respect to a vertical center plane Y that passes through the pipe axis center X of the existing water pipe 1.

[0047] In the first pipe cutting process, the cutting rotation of the hole saw 40 at a first drilling center position P1 that is offset to one side in the pipe transverse direction relative to the central plane Y causes the first drilling area (first drilling area in a plan view) of the hole saw 40 to extend beyond the central plane Y to the other side in the pipe transverse direction, and the first drilling opening width W1 in the pipe axis center X direction on the pipe circumferential surface of the existing water pipe 1 at one end in the pipe transverse direction becomes the valve insertion set width, thereby cutting the existing water pipe 1. In the next second pipe cutting step, the hole saw 40 rotates at a second drilling center position P2 that is offset to the other side in the pipe cross direction relative to the center plane Y, causing a second drilling area (second drilling area in plan view) H2 of the hole saw 40 to move beyond the center plane Y of the existing water pipe 1 to one side in the pipe cross direction, and communicate in the pipe cross direction with the drilling formed in the first pipe cutting step. Furthermore, the existing water pipe 1 can be cut and separated in a state in which the second drilling opening width W2 in the pipe axis center X direction on the pipe circumferential surface at the other end of the existing water pipe 1 in the pipe cross direction becomes the valve insertion set width.

[0048] As a result, compared to a single drilling operation using a hole saw 40 with a blade diameter larger than the outer diameter of the existing water pipe 1, the cutting area of ​​the existing water pipe 1 is smaller and the driving torque of the hole saw 40 during cutting is also smaller, making it possible to make the drilling equipment smaller and lighter. Furthermore, compared to three drilling operations using a hole saw 40 with a blade diameter smaller than the radius of the existing water pipe 1, the cutting process can be performed more efficiently and with fewer construction defects. Moreover, since the hole saw 40 having a blade diameter D1 larger than the radius of the existing water pipe 1 is used, the first drilling opening width W1 and the second drilling opening width W2 at both ends in the pipe cross direction of the existing water pipe 1 can be set to any valve insertion set width corresponding to the insertion width in the pipe axis center X direction of the inner valve case 23 equipped with the valve body 24. This makes it possible to expand the setting range of the valve insertion set width compared to three drilling operations using the hole saw 40 having a blade diameter smaller than the radius of the existing water pipe 1.

[0049] Furthermore, compared to a case in which the drilling center width W3 in the pipe axis center X direction between the intersections of the rotation trajectories of the hole saw 40 at the first drilling center position P1 and the second drilling center position P2 is set larger than, for example, the first drilling opening width W1 and the second drilling opening width W2 at both ends of the existing water pipe 1 in the pipe transverse direction, the cutting area of ​​the existing water pipe 1 is smaller and the driving torque of the hole saw 40 during cutting is also smaller, making it possible to make the drilling equipment smaller and lighter.

[0050] In the first tube cutting process and the second tube cutting process, a chip discharge process is carried out in which chips (cutting debris) generated by the cutting rotation of the hole saw 40 are discharged to the outside.

[0051] [4] Cutting device removal process 12, when the hole saw 40 drilling at the second drilling center position P2 reaches the drilling end position, the other side piece 1A cut and separated from the existing water pipe 1 is inside the hole saw 40. In this state, about half of the cross-sectional area of ​​the flow path in the existing water pipe 1 is secured compared to cutting with a hole saw larger than the outer diameter of the existing water pipe 1. Therefore, just like during the first drilling operation, the water flow in the existing water pipe 1 is less likely to be obstructed. The upper pipe wall of the section 1A in the hole saw 40 is locked and held by two locking bodies 46 of the center drill 45. Therefore, the hole saw 40, which is at the end of the drilling position, can be reliably pulled up together with the section 1A into the position changing attachment 6 and the storage space 43 in the drilling case 41.

[0052] When the hole saw 40 has returned to its predetermined storage position within the storage space 43, the work valve body 3D of the work on-off valve 3 is closed. After that, the upper flange 3C of the work valve case 3A and the lower flange 61A of the position changing attachment 6 are released from the bolts and nuts 63. The released position changing attachment 6, the drilling work case 41, and the cutting device 4 are integrally assembled to form the drilling equipment, which is then removed from the work on-off valve 3.

[0053] [5] Valve body installation process Although not shown, a valve insertion machine equipped with a working housing capable of storing the inner valve case 23 and a lifting mechanism for supporting the inner valve case 23 in the working housing so that it can be raised and lowered is attached to the work on-off valve 3. After that, the working valve body 3D of the work on-off valve 3 is opened, and the lifting mechanism of the valve insertion machine is driven to send the inner valve case 23 downward. As shown in Fig. 14, the inner valve case 23 is inserted to a predetermined valve body installation position through the valve body insertion port 22 of the valve body installation part 21 of the valve body 20 without touching the cut end surface 1a of the existing water pipe 1. At this time, a screw hole 21a is formed in the valve box flange 21A of the valve body attachment part 21, which is opposed in the vertical direction to the bolt insertion hole 23b formed in the valve cover part 23B of the inner valve box 23. An insertion guide bolt 33 that engages with the bolt insertion hole 23b of the valve cover part 23B from below and determines the insertion position of the inner valve box 23 is detachably screwed into the screw hole 21a of this valve box flange 21A. The fastening between the valve box flange 21A of the valve body mounting portion 21 of the valve box 20 and the valve lid portion 23B of the inner valve box 23 is carried out by inserting a fastening bolt (not shown) from above into the bolt insertion hole 23b of the valve lid portion 23B and screwing it into the screw hole 21a of the valve box flange 21A. In the pipe cutting process, the watertight bolt 34 is detachably attached to the screw hole 21a of the valve body flange 21A.

[0054] Then, as shown in Figures 14 and 15, when the fastening between the valve box flange 21A of the valve body mounting portion 21 of the valve box 20 and the valve cover portion 23B of the inner valve box 23 is completed, the work valve attachment 5 and the work on-off valve 3 are removed from the valve box flange 21A of the valve body mounting portion 21.

[0055] Next, a first example of this embodiment will be described with reference to FIG. In this first embodiment, the diameter D of a cast iron pipe, which is an example of an existing water pipe 1, is Φ600 (outer diameter 630.8 mm), the first and second drilling opening widths (valve insertion setting widths) W1 and W2 are 300 mm, and the drilling center width W3 is 300 mm. In the case of two drilling operations, the first tube cutting step and the second tube cutting step, the blade diameter D1 of the hole saw 40 is 440 mm. The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is 440 / 300 ≒ 1.47. In this first embodiment, in two drilling operations using a hole saw 40 with a blade diameter D1 larger than the radius of the existing water pipe 1, the ratio of the first and second drilling opening widths (valve insertion setting widths) W1, W2 as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is within the range of 1.1 to 1.5, so that it is possible to expand the setting range of the first and second drilling opening widths (valve insertion setting widths) W1, W2 while reducing the size and weight of the drilling equipment. However, in the case of a single drilling operation, the blade diameter D2 of the hole saw 40 is 700 mm, as shown in FIG. The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D2 of the hole saw 40 as the numerator is 700 / 300 ≒ 2.33. Furthermore, as shown by the diagonal lines in FIG. 13, the cutting area of ​​the existing water pipe 1 is smaller in two drilling operations than in one drilling operation, and the driving torque of the hole saw 40 during cutting is also smaller.

[0056] Next, a second example of this embodiment will be described with reference to FIG. In this second embodiment, the diameter D of a cast iron pipe, which is an example of an existing water pipe 1, is Φ1500 (outer diameter 1554 mm), the first and second drilling opening widths (valve insertion setting widths) W1 and W2 are 700 mm, and the drilling center width W3 is 700 mm. In the case of two drilling operations, the first tube cutting step and the second tube cutting step, the blade diameter D1 of the hole saw 40 is 1050 mm. The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is 1050 / 700 = 1.5. In this second embodiment, in two drilling operations using a hole saw 40 with a blade diameter D1 larger than the radius of the existing water pipe 1, the ratio of the first and second drilling opening widths (valve insertion setting widths) W1, W2 as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is within the range of 1.1 to 1.5, so that the setting range of the first and second drilling opening widths (valve insertion setting widths) W1, W2 can be expanded while the drilling equipment can be made smaller and lighter. However, in the case of a single drilling operation, the blade diameter D2 of the hole saw 40 is 1710 mm, as shown in FIG. 17(a). The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D2 of the hole saw 40 as the numerator is 1710 / 700 ≒ 2.44. Furthermore, as shown by the diagonal lines in FIG. 17(a), the cutting area of ​​the existing water pipe 1 is smaller in two drilling operations than in one drilling operation, and the driving torque of the hole saw 40 during cutting is also smaller.

[0057] Next, a third embodiment of this invention will be described with reference to FIG. In this third embodiment, the diameter D of a cast iron pipe, which is an example of an existing water pipe 1, is Φ1500 (outer diameter 1554 mm), the first and second drilling opening widths (valve insertion setting widths) W1 and W2 are 1000 mm, and the drilling center width W3 is 1000 mm. In the case of two drilling operations, the first tube cutting step and the second tube cutting step, the blade diameter D1 of the hole saw 40 is 1280 mm. The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is 1280 / 1000 = 1.28. In this third embodiment, in two drilling operations using a hole saw 40 with a blade diameter D1 larger than the radius of the existing water pipe 1, the ratio of the first and second drilling opening widths (valve insertion setting widths) W1, W2 as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is within the range of 1.1 to 1.5, so that it is possible to expand the setting range of the first and second drilling opening widths (valve insertion setting widths) W1, W2 while reducing the size and weight of the drilling equipment. However, in the case of a single drilling operation, the blade diameter D2 of the hole saw 40 is 1860 mm, as shown in FIG. 17(b). The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D2 of the hole saw 40 as the numerator is 1860 / 1000 = 1.86. Furthermore, as shown by the diagonal lines in FIG. 17(b), the cutting area of ​​the existing water pipe 1 is smaller in two drilling operations than in one drilling operation, and the driving torque of the hole saw 40 during cutting is also smaller.

[0058] Next, a fourth embodiment of this invention will be described with reference to FIG. In this fourth embodiment, the diameter D of a cast iron pipe, which is an example of an existing water pipe 1, is Φ1500 (outer diameter 1554 mm), the first and second drilling opening widths (valve insertion setting widths) W1 and W2 are 1300 mm, and the drilling center width W3 is 1300 mm. In the case of two drilling operations, the first tube cutting step and the second tube cutting step, the blade diameter D1 of the hole saw 40 is 1520 mm. The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is 1520 / 1300 ≒ 1.17. In this fourth embodiment, in two drilling operations using a hole saw 40 with a blade diameter D1 larger than the radius of the existing water pipe 1, the ratio of the first and second drilling opening widths (valve insertion setting widths) W1, W2 as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is within the range of 1.1 to 1.5, so that it is possible to reduce the size and weight of the drilling equipment while expanding the setting range of the first and second drilling opening widths (valve insertion setting widths) W1, W2. However, in the case of a single drilling operation, the blade diameter D2 of the hole saw 40 is 2030 mm, as shown in FIG. 17(c). The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D2 of the hole saw 40 as the numerator is 2030 / 1300 = 1.56. Furthermore, as shown by the diagonal lines in FIG. 17(c), the cutting area of ​​the existing water pipe 1 is smaller in two drilling operations than in one drilling operation, and the driving torque of the hole saw 40 during cutting is also smaller.

[0059] Next, a fifth embodiment of the present invention will be described with reference to FIG. In this fifth embodiment, the diameter D of a cast iron pipe, which is an example of an existing water pipe 1, is Φ2000 (outer diameter 2061 mm), the first and second drilling opening widths (valve insertion setting widths) W1 and W2 are 1400 mm, and the drilling center width W3 is 1400 mm. In the case of two drilling operations, the first tube cutting step and the second tube cutting step, the blade diameter D1 of the hole saw 40 is 1740 mm. The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is 1740 / 1400 ≒ 1.24. In this fifth embodiment, in two drilling operations using a hole saw 40 with a blade diameter D1 larger than the radius of the existing water pipe 1, the ratio of the first and second drilling opening widths (valve insertion setting widths) W1, W2 as the denominator to the blade diameter D1 of the hole saw 40 as the numerator is within the range of 1.1 to 1.5, so that it is possible to expand the setting range of the first and second drilling opening widths (valve insertion setting widths) W1, W2 while reducing the size and weight of the drilling equipment. However, in the case of a single drilling operation, the blade diameter D2 of the hole saw 40 is 2500 mm, as shown in FIG. The ratio of the first and second drilling opening widths (valve insertion setting widths) W1 and W2 at both ends of the existing water pipe 1 in the pipe cross direction as the denominator to the blade diameter D2 of the hole saw 40 as the numerator is 2500 / 1400 ≒ 1.78. Furthermore, as shown by the diagonal lines in FIG. 18, the cutting area of ​​the existing water pipe 1 is smaller in two drilling operations than in one drilling operation, and the driving torque of the hole saw 40 during cutting is also smaller.

[0060] [Another embodiment] (1) In the above embodiment, a butterfly valve 2 was used as an example of a valve, but the technology of the present invention can also be applied to installation methods for other types of valves, such as soft-seal gate valves for water supply.

[0061] (2) In the above embodiment, in order to configure the hole saw 40 so that the rotation axis of the hole saw 40 can be freely changed between the first mounting position corresponding to the first drilling center position P1 and the second mounting position corresponding to the second drilling center position P2, a method was adopted in which the position change attachment 6 is rotated 180 degrees relative to the work on-off valve 3 and replaced. However, this configuration is not limited to this. For example, the position change attachment 6 may be slid in the pipe transverse direction relative to the work on-off valve 3 to selectively change between the first mounting position and the second mounting position.

[0062] (3) In the above embodiment, as shown in Fig. 4 and Fig. 5, the valve box flange 21A of the valve element mounting portion 21 is provided with the inner O-ring 27 for sealing between the flange joint surface of the valve cover portion 23B and the outer O-ring 35 for sealing between the joint surface of the valve cover portion 23B and the first flange 5A of the working valve attachment 5, but the present invention is not limited to this arrangement. For example, the inner O-ring 27 may be provided on the flange joint surface of the valve cover portion 23B of the inner valve box 23. Also, the outer O-ring 35 may be provided on the flange joint surface of the first flange 5A of the working valve attachment 5. [Explanation of symbols]

[0063] 1 Existing pipes (existing water pipes) 3. Operational opening and closing valve 4 Cutting device 5 Working valve attachment 5A First Flange 5B Second flange 6 Position change attachment 20 Valve box 21 Valve body mounting part 24 Valve body 40 Hole Saw D1 Blade diameter P1 1st drilling center position P2 2nd drilling center position W1 Perforation opening width (1st perforation opening width) W2 Perforation opening width (second perforation opening width) W3 Perforated centre panel H1 Perforation area (1 perforation area) H2 Perforation area (2 perforation areas) X-tube core Y Center Plane

Claims

1. A valve installation method for an existing pipe, comprising: a valve box exterior installation step of exteriorizing a valve box in a valve installation area of ​​an existing pipe; a cutting device installation step of installing a cutting device having a hole saw for cutting and separating a valve body insertion portion of the existing pipe on the valve box side; a pipe cutting step of cutting and separating a valve body insertion portion of the existing pipe in an uninterrupted flow state by cutting rotation of the hole saw; a cutting device removal step of removing the cutting device from the valve box side; and a valve body installation step of installing a valve body on the valve box, In the cutting device installation step, the hole saw having a blade diameter larger than the radius of the existing pipe is attached to the cutting device, the pipe cutting step includes a first pipe cutting step in which the hole saw is rotated at a first drilling center position offset to one side in a pipe transverse direction with respect to a central plane passing through the pipe axis of the existing pipe to cut and separate the existing pipe in a state in which the drilling area of ​​the hole saw extends beyond the central plane to the other side in the pipe transverse direction and a drilling opening width in the pipe axial direction on the pipe peripheral surface of one end of the existing pipe in the pipe transverse direction becomes a valve insertion set width; and a second pipe cutting process, in which the hole saw is rotated at a second drilling center position that is offset to the other side in the pipe transverse direction with respect to the central plane passing through the pipe axis of the existing pipe, so that the drilling area of ​​the hole saw extends beyond the central plane of the existing pipe to one side in the pipe transverse direction and the drilling opening width in the pipe axial direction on the pipe circumferential surface of the other end of the existing pipe in the pipe transverse direction becomes a valve insertion set width.

2. A method for installing a valve on an existing pipe, comprising: a valve box exterior fitting process for fitting a valve box to a valve installation area of ​​an existing pipe; a cutting device fitting process for fitting a cutting device having a hole saw for cutting and separating a valve body insertion portion of the existing pipe to the valve box side; a pipe cutting process for cutting and separating a valve body insertion portion of the existing pipe under an uninterrupted flow condition by cutting rotation of the hole saw; a cutting device removal process for removing the cutting device from the valve box side; and a valve body fitting process for fitting a valve body to the valve box, In the cutting device installation step, the hole saw having a blade diameter larger than the radius of the existing pipe is attached to the cutting device, the pipe cutting step includes a first pipe cutting step in which the hole saw is rotated at a first drilling center position offset to one side in a pipe transverse direction with respect to a central plane passing through the pipe axis of the existing pipe to cut and separate the existing pipe in a state in which the drilling area of ​​the hole saw extends beyond the central plane to the other side in the pipe transverse direction and a drilling opening width in the pipe axial direction on the pipe peripheral surface of one end of the existing pipe in the pipe transverse direction becomes a valve insertion set width; a second pipe cutting process for cutting and separating the existing pipe in a state where a drilling area of ​​the hole saw extends beyond the central plane of the existing pipe to one side in the pipe transverse direction and a drilling opening width in the pipe axial direction on the pipe peripheral surface of the other end of the existing pipe in the pipe transverse direction becomes a valve insertion set width by cutting and rotating the hole saw at a second drilling center position offset to the other side in the pipe transverse direction with respect to the central plane passing through the pipe axis of the existing pipe, In the cutting device installation process, a position-changing attachment is detachably provided between the cutting device and a work opening / closing valve joined to the valve body mounting portion of the valve box, and the cutting device can be changed in the pipe transverse direction by rotating the attachment 180 degrees relative to the work opening / closing valve.In the pipe cutting process, the same position-changing attachment is rotated 180 degrees relative to the work opening / closing valve, so that the cutting device can be freely changed between a first attachment position in which the rotation axis of the hole saw corresponds to the first drilling center position, and a second attachment position in which the rotation axis of the hole saw corresponds to the second drilling center position.This is a valve installation method for existing pipes.

3. 3. The method for installing a valve in an existing pipe according to claim 1, wherein the blade diameter of the hole saw is set to be larger than the radius of the existing pipe and smaller than the outer diameter of the existing pipe.

4. The method for installing a valve in an existing pipe according to any one of claims 1 to 3, wherein the ratio of the valve insertion setting width, which is the drilling opening width at both ends of the existing pipe in the pipe cross direction, to the blade diameter of the hole saw as the numerator is set to 1.1 to 1.

5.

5. A valve installation method for an existing pipe as described in any one of claims 1 to 4, wherein a central width of drilling in the pipe axial direction between two intersections where the rotational trajectory of the hole saw at the first drilling center position and the rotational trajectory of the hole saw at the second drilling center position intersect is set to be the same or approximately the same as the drilling opening width at both ends of the existing pipe in the pipe transverse direction.

6. A valve installation method for an existing pipe as described in any one of claims 1 to 5, in which, in the cutting device installation process, a work valve attachment is provided between the valve body mounting portion of the valve box and the work on-off valve on the cutting device side, the work valve attachment having a first flange that can be flange-joined to the valve body mounting portion and a second flange that can be flange-joined to the work on-off valve.

Images