Piping, piping systems, evaluation equipment for piping systems

Abstract

The present invention aims to provide a reducer tube. [Solution] The pipe according to the present invention is a pipe having a small diameter section and a large diameter section, with a reduced diameter section between the small diameter section and the large diameter section, wherein the angle at which the central axes of the small diameter section, the large diameter section and the reduced diameter section intersect with the line segment connecting the boundary position between the small diameter section and the reduced diameter section as drawn when viewing the longitudinal cross-section of the small diameter section and the boundary position between the large diameter section and the reduced diameter section as drawn when viewing the longitudinal cross-section of the large diameter section is defined as the inner surface inclination angle θ of the reduced diameter section, the length of the reduced diameter section in the direction along the central axis is defined as the reduced diameter length s, and the inner diameter at the boundary position of the large diameter section is defined as the inlet inner diameter, the value of the ratio expressed as (inlet inner diameter / reduced diameter section length) is 1.5 or more, and the cavitation coefficient is 2.0 to 3.5.

Description

[Technical Field]

[0001] This invention relates to piping, piping systems, and an evaluation device for piping systems. [Background technology]

[0002] Reducer pipes have traditionally been used to change the diameter of pipes. When a water channel is constructed using these reducer pipes, sections of the flow path either narrow or widen rapidly within the pipe, resulting in pressure loss. If the pressure loss is large, a stable water flow may not be obtained. Furthermore, when constructing a water channel using a reducer pipe, the overall length of the reducer pipe is designed to be long to address concerns about pressure loss. However, if the overall length of the reducer pipe is too long, the pipe itself becomes large, leading to problems with ease of installation. Patent Document 1 below discloses a joint using a reducer pipe as a piping material for ultrapure water, which is formed from a polyethylene resin composition. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-145138 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The fitting described in Patent Document 1 is a type of reducer pipe in which the inner diameter of one end is larger than the inner diameter of the other end, and the inner diameter of the pipe changes in the central part of the fitting. Therefore, even with this fitting, if the total length is short, the inlet loss and outlet loss are continuous, resulting in a large pressure loss and a high risk of cavitation. Therefore, in order to avoid pressure loss, the total length needs to be increased.

[0005] In view of the circumstances described above, the present invention aims to provide a piping system that employs a structure in which a reduced diameter section is located at the boundary between a small diameter section and a large diameter section, thereby reducing pressure loss and suppressing cavitation while keeping the overall length of the reduced diameter section small. [Means for solving the problem]

[0006] To solve the aforementioned problems, the present invention proposes the following embodiments. <1> A pipe according to one embodiment of the present invention is a pipe having a small diameter section and a large diameter section, with a reduced diameter section between the small diameter section and the large diameter section, wherein the angle at which the central axes of the small diameter section, the large diameter section and the reduced diameter section intersect with the line segment connecting the boundary position between the small diameter section and the reduced diameter section as drawn when viewing the longitudinal cross-section of the small diameter section and the boundary position between the large diameter section and the reduced diameter section as drawn when viewing the longitudinal cross-section of the large diameter section is defined as the inner surface inclination angle θ of the reduced diameter section, the length of the reduced diameter section in the direction along the central axis is defined as the reduced diameter length s, and the inner diameter at the boundary position of the large diameter section is defined as the inlet inner diameter, the value of the ratio expressed as (inlet inner diameter / reduced diameter section length) is 1.5 or more, and the cavitation coefficient is 2.0 to 3.5.

[0007] In a pipe having a large-diameter section and a small-diameter section, even if the configuration includes a reduced-diameter section that protrudes inward from the large-diameter section, by setting the ratio value expressed as (inlet inner diameter / reduced-diameter section length) to 1.5 or more and suppressing the cavitation coefficient within a specific range, it is possible to provide a configuration with a low probability of cavitation occurrence while keeping the reduced-diameter section length smaller compared to the inlet inner diameter.

[0008] <2> The aforementioned <1> In the piping related to this, it is preferable that the inner surface inclination angle θ of the reduced diameter portion is 15 to 30 degrees.

[0009] By setting the inner surface inclination angle of the reduced diameter section to 15-30°, a smooth water flow can be guided from the large diameter section to the small diameter section, providing piping with a low risk of cavitation.

[0010] <3> The aforementioned <1> In the piping related to this, it is preferable that the cavitation coefficient is 2.2 to 3.1.

[0011] By suppressing the cavitation coefficient to a low level, even if water flows through a reduced-diameter portion that protrudes inward from the large-diameter portion, the probability of cavitation occurrence can be suppressed to a low level, and a pipe that can maintain a smooth water flow can be provided.

[0012] <4>In the pipe according to <1>, it is preferable that the value of the ratio represented by (inlet inner diameter / reduced-diameter portion length) is in the range of 1.5 to 3.9.

[0013] By selecting the range of 1.5 to 3.9 as the value of the ratio represented by (inlet inner diameter / reduced-diameter portion length), it is possible to provide a pipe that induces a smooth water flow while suppressing the length of the reduced-diameter portion as much as possible.

[0014] <5>In the pipe according to <1>, it is preferable that the inner peripheral contour of the reduced-diameter portion drawn in the longitudinal section of the reduced-diameter portion is an S-shaped curve.

[0015] As a specific example of the reduced-diameter portion shape, a shape in which the inner peripheral contour of the reduced-diameter portion draws an S-shaped curve in the longitudinal section contour can be adopted.

[0016] <6>In the pipe according to <1>, it is preferable that a straight pipe is connected to the large-diameter portion. <7>In the pipe according to <7>, it is preferable that a bead is formed at the connection portion between the large-diameter portion and the straight pipe.

[0017] <8>A pipe system according to one embodiment of the present invention includes a pipe according to any one of <1> to <7> and a joint connected to the pipe.

[0018] <9>An evaluation device for a pipe system according to one embodiment of the present invention is an evaluation device for the pipe system according to <8>, and includes an acquisition unit that acquires the original pressure of the pipe system, the flow rate of the pipe system, and an index indicating the pipe system, and a search unit that searches for an index indicating whether drainage by the pipe system is possible based on the information acquired by the acquisition unit.

Effect of the Invention

[0019] In the case of the pipe according to the present invention, in a pipe having a large-diameter portion and a small-diameter portion, even if it has a reduced-diameter portion having a shape that protrudes inward from the large-diameter portion, by setting the value of the ratio represented by (inlet inner diameter / reduced-diameter portion length) to 1.5 or more and suppressing the cavitation coefficient within a specific range, it is possible to provide a configuration with a low cavitation generation probability while suppressing the length of the reduced-diameter portion compared to the inlet inner diameter.

Brief Description of the Drawings

[0020] [Figure 1] A side view showing an example of applying the pipe of the first embodiment according to the present invention to a pipe joint. [Figure 2] A partial cross-sectional view showing an example of the pipe according to the first embodiment. [Figure 3] A longitudinal cross-sectional view showing the detailed structure of the reducer pipe applied to the pipe according to the first embodiment. [Figure 4] A partial cross-sectional view showing an example of the pipe according to the second embodiment of the present invention. [Figure 5] An explanatory view of the case where the pipe according to the third embodiment of the present invention is joined to another pipe. [Figure 6] An explanatory view of the case where the pipe according to the third embodiment of the present invention is joined to another pipe. [Figure 7] An explanatory view of the case where the pipe according to the fourth embodiment of the present invention is joined to another pipe. [Figure 8] A cross-sectional view of an example of forming the pipe system according to the embodiment inside an existing pipe. [Figure 9] A block diagram showing an evaluation device for the pipe system according to the embodiment. [Figure 10] A diagram showing an outline of an example of the hardware configuration of the evaluation device for the pipe system according to the embodiment. [Figure 11] A diagram showing an example of display for the evaluation of the pipe system searched by the evaluation device for the pipe system according to the embodiment. [Figure 12] A block diagram showing a calculation device according to the embodiment.

Modes for Carrying Out the Invention

[0021] <First Embodiment> Hereinafter, an example of applying a reducer pipe to piping according to the first embodiment of the present invention and to the pipe joint will be described with reference to Figures 1 to 3. Note that in the following description, the drawings may be enlarged to show characteristic parts. Figure 1 shows an example of a pipe joint where two horizontally arranged pipes 1 and 1 are connected by an electrofusion joint 3, with integrated reducer pipes (joint pipes, pipe fittings) 2 at their ends. Figure 2 is a partial cross-sectional view showing an example of pipe 1, and Figure 3 shows the detailed cross-sectional structure of the reducer pipe 2. The piping 1 is formed by integrating synthetic resin reducer pipes 2, also made of synthetic resin, with both ends of a synthetic resin piping body (straight pipe) 1A by joining means such as fusion or adhesive. Alternatively, the piping body 1A and the reducer pipes 2 may be a single molded product made of synthetic resin. The pipe body 1A consists of a straight pipe having a uniform inner diameter and a uniform outer diameter in the longitudinal direction. Therefore, the pipe body 1A has a circumferential wall with a uniform wall thickness in the longitudinal direction.

[0022] The reducer pipe 2 has a large-diameter section 2A integrated into one end on the pipe body 1A side, and a small-diameter section 2B integrated into the other end on the side away from the pipe body 1A. It also has a reduced-diameter section 2C between the large-diameter section 2A and the small-diameter section 2B, with an inner diameter that gradually narrows. The outer diameter of the large-diameter section 2A is equal to the outer diameter of the main pipe body 1A, and the inner diameter of the large-diameter section 2A is equal to the inner diameter of the main pipe body 1A. Since the outer and inner diameters of the large-diameter section 2A are constant in the longitudinal direction, the large-diameter section 2A has a constant wall thickness in the longitudinal direction. The outer diameter of the reduced-diameter section 2C is equal to the outer diameter of the large-diameter section 2A. In the reduced-diameter section 2C, the inner diameter of one end connected to the large-diameter section 2A is equal to the inner diameter of the large-diameter section 2A, but the inner diameter of the reduced-diameter section 2C gradually decreases as it moves away from the large-diameter section 2A, and at the other end connected to the small-diameter section 2B, it is equal to the inner diameter of the small-diameter section 2B. The small-diameter portion 2B has a constant outer diameter and a constant inner diameter in the longitudinal direction. Therefore, the small-diameter portion 2B has a peripheral wall with a constant thickness in the longitudinal direction.

[0023] In Figure 2, the connection point between the main pipe body 1A and the large-diameter section 2A of the reducer pipe 2 is indicated by the dashed line 5. The dashed line 5 is for convenience only, and the connection boundary may not be visible depending on the joining method, such as fusion welding. When a large-diameter section 2A made of resin is fused to a main pipe body 1A made of resin, a bead is formed at the fusion joint on the outer circumference of both the main pipe body 1A and the large-diameter section 2A. This bead is not shown in the drawings.

[0024] Here, the bead is formed, for example, by butt fusion of the pipe body 1A and the large-diameter section 2A. Below, an example of butt fusion of the pipe body 1A and the large-diameter section 2A will be described. When performing butt fusion, it is preferable to first prepare the ends of the pipe body 1A and the large-diameter section 2A to be joined by, for example, cutting or other methods as necessary, and then clean them.

[0025] After cleaning, the end faces of the main pipe body 1A and the large-diameter section 2A are brought together, and a plate-shaped heater (not shown) is placed between the ends. Next, the heater is energized to heat each end to a temperature higher than the softening point and lower than the melting point for a predetermined time, and this temperature is maintained. After this, the heater is removed from between the ends. Then, the high-temperature ends are brought together and cooled for a predetermined time while maintaining the required butting force. The butting portions of the high-temperature ends are deformed into a shape having the aforementioned beads (built-up portions), and the end faces are fused together. The bead refers to, for example, the flange-like portion that spreads out along the circumferential direction on the outer and inner circumferential surfaces of the main pipe body 1A and the large-diameter section 2A (i.e., a series of large-diameter sections) as a result of pressing the ends of the main pipe body 1A and the large-diameter section 2A against each other while maintaining a high temperature.

[0026] In the case of butt fusion as described above, the resin of the pipe body 1A and the large-diameter section 2A (the resin of the pipe) may form a bead (built-up section). If the pipe body 1A and the large-diameter section 2A (pipe) are multi-layered pipes, for example, the resin of the inner layer may form a bead (built-up section). Furthermore, the bead (build-up portion) is not limited to the form formed by so-called butt fusion as described above. The bead (build-up portion) can be formed by welding as appropriate. Here, welding may be, for example, hot air welding (so-called hot jet welding), hot plate welding (so-called butt fusion), friction welding, impulse seal welding, flame welding, high-frequency welding, ultrasonic welding, etc. In this case, for example, when the welding rod is metal (when it is metal welding), the bead (build-up portion) may be the molten and solidified weld metal formed at the joint when the pipe body 1A and the large diameter portion 2A are joined by welding. Also, in the case of hot jet welding, etc. (when it is resin welding), the bead (build-up portion) may be formed by the resin of the welding rod. In this case, the welding rod may be made of the same resin as the pipe; for example, if the pipe is PE, the welding rod may also be PE.

[0027] When beads are present at the butt joints of the ends of the main pipe body 1A and the large-diameter section 2A, beads are provided at both ends of the series of large-diameter sections (main pipe body 1A and large-diameter section 2A) formed by the main pipe body 1A and the large-diameter section 2A. The main pipe body 1A and the reducer pipe 2 are integrally formed to form a straight pipe by connecting the large-diameter section 2A to the main pipe body 1A by butt fusion. That is, the pipe 1 is formed as a pipe that integrates a pair of small-diameter sections 2B, a series of large-diameter sections (main pipe body 1A and large-diameter section 2A), and a pair of reduced-diameter sections 2C.

[0028] In the first embodiment, an example is described in which the reducer pipe 2 is connected to the main pipe body 1A by butt fusion, but the reducer pipe 2 and the main pipe body 1A may also be connected by an electrofusion joint. Also, in the first embodiment, an example is described in which the pipe 1 is formed integrally by connecting the reducer pipe 2 to the main pipe body 1A by butt fusion, but the entire pipe 1 may be molded together as a single pipe. For example, if the main pipe body 1A is formed by extrusion molding, the pipe end of the extruded pipe can be thermally deformed to form a reduced diameter section and a small diameter section, thereby obtaining the cross-sectional structure shown in Figure 2 that does not have a bead. In this case, for example, a cylindrical raw tube of thermoplastic resin may be inserted into a mold having a cavity corresponding to the shape of the reducer pipe 2, the raw tube may be heated to a predetermined temperature or higher (e.g., 150°C or higher), and the raw tube may be pressed with a predetermined pressure (e.g., 0.07 MPa or higher) in the direction of insertion into the mold to form the reducer pipe 2.

[0029] Figure 3 is a longitudinal cross-sectional view showing the detailed structure of the reducer tube 2. As clearly shown in Figure 3, the inner circumferential wall of the reduced-diameter section 2C has an inner circumferential surface that gradually narrows in diameter from the large-diameter section 2A to the small-diameter section 2B. In Figure 3, for convenience, boundary line 6 is drawn at the boundary between the large diameter section 2A and the reduced diameter section 2C, and boundary line 7 is drawn at the boundary between the reduced diameter section 2C and the small diameter section 2B. Additionally, boundary line 8 is drawn midway between boundary line 6 and boundary line 7.

[0030] In Figure 3, the line indicating the left end of the large-diameter section 2A (the open end of the large-diameter section 2A, the end on the pipe body 1A side) is denoted as the large-diameter end line 10, and the line indicating the right end of the small-diameter section 2B (the open end of the small-diameter section 2B) is denoted as the small-diameter end line 11. In Figure 3, the outer diameter of the large-diameter section 2A is denoted as D1, and the inner diameter (inlet inner diameter) of the large-diameter section 2A is denoted as d1. Similarly, the outer diameter of the small-diameter section 2B is denoted as D2, and the inner diameter (outlet inner diameter) of the small-diameter section 2B is denoted as d2. In Figure 3, the wall thickness of the large-diameter section 2A is denoted as t1, and the wall thickness of the small-diameter section 2B is denoted as t2. Furthermore, the difference between the radius of the outer diameter of the large-diameter section 2A and the radius of the outer diameter of the small-diameter section 2B is denoted as H. The combined length of the large-diameter section 2A and the reduced-diameter section 2C is denoted as l1, and the length of the small-diameter section 2B is denoted as l2. Furthermore, l1 + l2 is denoted as L. L represents the total length (overall length) of the reducer tube 2. In Figure 3, the distance between the large-diameter end line 10 and the boundary line 6 is denoted as l3, and the distance between the boundary line 7 and the small-diameter end line 11 is denoted as l4. l3 corresponds to the length of the large-diameter section 2A, and l4 corresponds to the length of the small-diameter section 2B. In Figure 3, the distance between boundary line 6 and boundary line 8 is denoted as l5, and the distance between boundary line 8 and boundary line 7 is denoted as l6. In Figure 3, the outer diameter of the reduced-diameter section 2C is constant on the larger-diameter section 2A side, but the corners of the reduced-diameter section 2C are chamfered by providing a chamfered section 2e at the end on the smaller-diameter section 2B side. The width of the chamfered section 2e is denoted as C. On the outer circumference of the reduced diameter portion 2C, a stepped portion 2f is formed where the reduced diameter portion 2C extends to the outer circumference of the small diameter portion 2B. A rounded portion R1 is formed at the bottom of the stepped portion 2f.

[0031] In Figure 3, the inner circumferential contour of the longitudinal section of the reducer tube 2 is shown to be an S-shaped inner contour (S-curve) extending from the large diameter section 2A to the small diameter section 2B. In Figure 3, the angle at which the central axis O1 of the reducer tube 2 intersects the line segment L7 connecting the boundary position of the small diameter section 2B and the reduced diameter section 2C with the boundary position of the large diameter section 2A and the reduced diameter section 2C, along the S-shaped inner contour, is denoted as the inner inclination angle θ of the reduced diameter section. The central axis O1 of the reducer tube 2 is the same as the central axis of the large-diameter section 2A, the small-diameter section 2B, and the reduced-diameter section 2C. In Figure 3, along line segment L7, a concave curve 12 is formed on the inner surface of the reduced-diameter portion 2C between boundary line 6 and boundary line 8. Along line segment L7, a convex curve 13 is formed on the inner surface of the reduced-diameter portion 2C between boundary line 8 and boundary line 7. These concave curve 12 and convex curve 13 form an S-shape in the inner circumferential contour of the longitudinal cross-section of the reduced-diameter portion 2C. In Figure 3, the radius of curvature of the arc-shaped concave curve 12 is denoted as R2, and the radius of curvature of the arc-shaped convex curve 13 is denoted as R3. In this way, an inclined surface 14 is formed on the inner surface of the reduced diameter portion 2C, with its contour represented by the concave curve 12 and the convex curve 13.

[0032] The position of boundary line 6, which indicates the boundary between the large-diameter section 2A and the reduced-diameter section 2C shown in Figure 3, is defined as follows. The inner diameter of the large-diameter section 2A is constant from the left end to the right end of Figure 3, but the inner diameter of the reduced-diameter section 2C gradually decreases from the position of boundary line 6. Therefore, by precisely measuring the inner diameter using a measuring instrument such as an internal diameter caliper, the position where the inner diameter value changes by 1% or more from the inner diameter value of the large-diameter section 2A is interpreted as the starting point of the reduced-diameter section 2C, and this starting point is defined as the boundary position between the large-diameter section 2A and the reduced-diameter section 2C. In Figure 3, boundary line 6 is drawn to show this position. Similarly, the inner diameter of the small-diameter section 2B is constant from the right end to the left end in Figure 3, but the inner diameter of the reduced-diameter section 2C gradually increases at the boundary line 7. Therefore, by precisely measuring the inner diameter using a measuring instrument such as an inner diameter caliper, the point where the inner diameter value changes by 1% or more from the inner diameter value of the small-diameter section 2B is interpreted as the starting point of the reduced-diameter section 2C, and this starting point is defined as the boundary position between the small-diameter section 2B and the reduced-diameter section 2C. In Figure 3, boundary line 7 is drawn to indicate this position.

[0033] In the reducer pipe 2 of this embodiment, there are no particular restrictions on the inner diameters of the large-diameter section 2A and the small-diameter section 2B, but the following combinations are possible to match the standards of commercially available pipes. 1. A combination of a large diameter section with a nominal diameter of 75A and a small diameter section with a nominal diameter of 50A. 2. Combination of a large diameter section with a nominal diameter of 100A and a small diameter section with a nominal diameter of 75A 3. Combination of a large diameter section with a nominal diameter of 150A and a small diameter section with a nominal diameter of 100A 4. Combination of a large diameter section with a nominal diameter of 200A and a small diameter section with a nominal diameter of 150A

[0034] In these typical combinations, the dimensions of each part, as explained earlier, will be described in detail below. 1. A combination of a large diameter section with a nominal diameter of 75A and a small diameter section with a nominal diameter of 50A. With this combination, the aforementioned values ​​can be set as follows. Outer diameter D1=90mm, D2=63mm, d1=72.6mm, d2=50.7mm, Thickness t1=8.2mm, t2=5.8mm, L=113.3mm, H=13.5mm, R1=3.0mm, R2=11.1mm, R3=11.1mm, l1=59.3mm, l2=54mm, l3=40mm, l4=54mm, l5=9.6mm, l6=9.6mm, C=5.0mm. Note that these values ​​are rounded for illustrative purposes, so calculations using these values ​​may not be strictly consistent. The same applies to items 2-4 below.

[0035] 2. Combination of a large diameter section with a nominal diameter of 100A and a small diameter section with a nominal diameter of 75A With this combination, the aforementioned values ​​can be set as follows. Outer diameter D1=125mm, D2=90mm, d1=100.8mm, d2=72.6mm, thickness t1=11.4mm, t2=8.2mm, L=129.8mm, H=17.5mm, R1=3. 0mm, R2=14.3mm, R3=14.3mm, l1=64.8mm, l2=65mm, l3=40mm, l4=65mm, l5=12.4mm, l6=12.4mm, C=5.0mm.

[0036] 3. Combination of a large diameter section with a nominal diameter of 150A and a small diameter section with a nominal diameter of 100A With this combination, the aforementioned values ​​can be set as follows. Outer diameter D1=180mm, D2=125mm, d1=145.3mm, d2=100.8mm, thickness t1=16.4mm, t2=11.2mm, L=159.0mm, H=27.5mm, R1=3 .0mm, R2=22.5mm, R3=22.5mm, l1=79.0mm, l2=80mm, l3=40mm, l4=80mm, l5=19.5mm, l6=19.5mm, C=10.0mm.

[0037] 4. Combination of a large diameter section with a nominal diameter of 200A and a small diameter section with a nominal diameter of 150A With this combination, the aforementioned values ​​can be set as follows. Outer diameter D1=250mm, D2=180mm, d1=201.9mm, d2=145.3mm, thickness t1=22.7mm, t2=16.4mm, L=189.8mm, H=35.0mm, R1=3. 0mm, R2=28.7mm, R3=28.7mm, l1=89.8mm, l2=100mm, l3=40mm, l4=100mm, l5=24.9mm, l6=24.9mm, C=10.0mm.

[0038] The SDR value, which is the ratio (D1 / t1) of the outer diameter D (outer diameter D1) to the wall thickness T (thickness t1) of the pipe body 1A, may be 13.5 or less. If the SDR value exceeds 13.5, the pipe thickness becomes too thin, and there is a risk that it will not be able to withstand the internal pressure of the fluid when fluid flows through it. If the SDR value is too low, the pipe thickness becomes too thick, and there is a risk that a sufficient flow rate cannot be secured. For this reason, the lower limit of the SDR value may be 6 or higher, or 7.4 or higher.

[0039] In general, when designing pipe thickness, for pipes through which water flows, the tensile circumferential stress generated in the pipe due to internal water pressure (tensile stress generated in the circumferential direction in the cross-section of the pipe) is known to follow the Naday equation shown in equation (1) below. σ=P(Dt) / 2t …(1) formula However, in equation (1), σ: tensile circumferential stress generated in the pipe (MPa), P: internal water pressure (MPa), D: outer diameter of the pipe (mm), and t: thickness of the pipe (mm).

[0040] Based on Naday's equation mentioned above, it is preferable to design the pipe thickness such that the stress generated at the design internal pressure (maximum allowable stress) has a safety factor of 2 relative to the 50-year creep strength of the polyethylene pipe for water distribution. For example, this relationship can be expressed by equation (2) below. σ 50 / S1=P d (Dt) / 2t …(2) formula However, in equation (2), σ 50 : 50-year creep strength (10 MPa) of polyethylene pipes for water distribution, S1:σ 50 The safety factor for P (which we will assume is 2 here), dMaximum allowable pressure (hydrostatic pressure 0.75 × water hammer pressure 0.25 = 1.0 PMa) By rearranging equation (2) above, the value of SDR (Standard Dimension Ratio) can be calculated using the following equation (3). SDR = D / t = 1 + (2·σ) 50 ) / (P d ·S1)=1+(2×10) / (1×2)=11…(3) formula

[0041] According to the pipe thickness design for water pipes calculated with the aforementioned safety factor of 2, an SDR value of 11 is considered good. However, for the rehabilitation of pipes where the internal pressure can be estimated to be small, such as polyethylene pipes for sewage, a value of 13.5 or less is desirable. Furthermore, if the standard SDR value for polyethylene pipes for water pipes is 11, the SDR value when the flow rate decreases by 40% (calculated assuming a velocity coefficient of 140 and a common dynamic gradient of 3%) is less than SDR 6, so an SDR value of 6 or higher is preferable.

[0042] The synthetic resin constituting the main piping body 1A and the reducer pipe 2 is preferably made of a thermoplastic resin such as a polyolefin resin. Resins made of polyolefin resin have a higher tensile break elongation than rigid polyvinyl chloride pipes, as measured according to JIS K 6815-1 and JIS K 6815-3. While the tensile break elongation of rigid polyvinyl chloride pipes is 50-150%, the tensile break elongation of polyolefin resin pipes is 350% or more. In particular, according to the extrapolation method specified in ISO / TR9080, high-density polyethylene pipes of PE100 have a tensile break elongation of 500% or more, thus better suppressing damage caused by earthquakes.

[0043] The polyolefin resin is not particularly limited, but examples of suitable materials include polyethylene, polypropylene, polybutene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, and poly-αolefin. Among these, polyethylene is preferable from the viewpoint of strength and other factors. Furthermore, when polyethylene is selected, it is desirable to appropriately choose one of the following types, such as low-density polyethylene, medium-density polyethylene, or high-density polyethylene, depending on the required durability desired for the main pipe body 1A and the reducer pipe 2. From the standpoint of not affecting seismic resistance, durability, water quality, etc., polyethylene resin piping can be used. In particular, when the main pipe body 1A and the reducer pipe 2 are used for water supply applications, high-density polyethylene resin pipes are preferable.

[0044] The specific gravity of the thermoplastic resin is not particularly limited, but for example, 942-953 kg / m³ 3 The specific heat of thermoplastic resins is not particularly limited, but for example, it is 1.9 to 2.3 kJ / kg·K. The thermal conductivity of thermoplastic resins is not particularly limited, but for example, it is 0.46 to 0.5 W / m·K. The thermoplastic resin may be a composition containing additives such as pigments, UV absorbers, antioxidants, and lubricants. The melting point of the thermoplastic resin (i.e., the melting temperature of the small diameter portion 2B) is not particularly limited, but is preferably 125 to 260°C, and more preferably 125 to 150°C.

[0045] The main piping body 1A and the reducer pipe 2 may have a multilayer structure with a surface layer on at least one of the outer and inner surfaces. For example, by having a surface layer containing ethylene-vinyl alcohol copolymer resin, the pipe body 1A and the reducer pipe 2 can be used for any purpose, such as water supply pipes, gas pipes, or sewer pipes. This is because the surface layer containing ethylene-vinyl alcohol copolymer resin makes it difficult for gases such as hydrogen, oxygen, propane, and butane, as well as hydrocarbons such as gasoline and benzene, to permeate.

[0046] The surface layer may contain, for example, at least one of inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers, carbon fibers, silicon-titanium-carbon composite fibers, boron fibers, or metal fibers. Examples of organic fibers include aramid fibers, vinylon fibers, polyester fibers, or polyamide fibers. Including these fibers in the surface layer increases the tensile strength of the pipe body 1A and the reducer pipe 2, and further suppresses thermal expansion. The surface layer may also contain fluororesin. Including fluorine in the surface layer increases resistance to acids and alkalis (chemical resistance). Alternatively, a layer similar to the surface layer may be provided within the walls of the pipe body 1A and the reducer pipe 2. However, even without a surface layer, the pipe 1 can still be used for the aforementioned purposes.

[0047] As shown in Figure 1, the left and right pipes 1 are joined together by an electrofusion joint 3 with the reducer pipes 2 butted together. As an example, the electrofusion joint 3 has a single-tube resin pipe body 16 made of the same resin as the resin that makes up the reducer pipe 2, and an electric heating wire arranged spirally on the inner circumferential surface of the resin pipe body 16, which is not shown in Figure 1. The resin pipe body 16 has a length and inner diameter that allows the end of the small-diameter section 2B to be joined to be inserted for the required length. The ends of the heating wires, which are spirally arranged on the inner surface of the resin pipe body 16, are connected to terminals 17 and 18 that protrude from the outer surface of the resin pipe body 16.

[0048] As shown in Figure 1, the tip ends of the small-diameter sections 2B are inserted into one and the other sides of the resin pipe body 16 in the longitudinal direction, and the connection wires of the power supply controller (not shown) are connected to terminals 17 and 18. After this, power is supplied from the controller to the heating element to heat it up. After supplying the required amount of power for a predetermined time, the power is stopped and it is allowed to cool, allowing the pipe body 1A to be joined by extending it through the fused joint created by the electrofusion joint 3. By supplying power to the heating element, the inner surface of the resin pipe body 16 and the outer surface of the small-diameter section 2B fuse together, allowing the pipe bodies 1A, 1A to be joined by fusion. As shown in Fig. 1, if the lengths of the tips of terminals 17 and 18 are set such that they do not protrude outward from the outer peripheral surface of the reducer pipe 2, a well-fitting connection can be achieved.

[0049] As shown in Fig. 1, water flows from one pipe body 1A connected as described to the other pipe body 1A. When water flows, the water flows from the large-diameter portion 2A through the reduced-diameter portion 2C to the small-diameter portion 2B. In order to make the flow of water smooth, it is desirable that the inner surface inclination angle θ of the reduced-diameter portion described above is in the range of 15° to 45°. Further, it is more preferable that the inner surface inclination angle θ of the reduced-diameter portion is in the range of 15° to 30°. If the inner surface inclination angle θ of the reduced-diameter portion is less than 15°, the length of the reducer pipe 2 becomes long, and the length of the connection portion of the adjacent pipe body 1A becomes long. If the inner surface inclination angle θ of the reduced-diameter portion exceeds 45°, cavitation due to pressure loss is likely to occur in the region from the large-diameter portion 2A to the small-diameter portion 2B or in the downstream region thereof.

[0050] Also, in order to suppress the length of the reducer pipe 2 as much as possible, as the value of the ratio represented by (inlet inner diameter / reduced-diameter portion length), a value of 1.5 or more, more preferably 3.0 or more can be selected. Here, as shown in Fig. 3, for example, the inlet inner diameter is d1, and the reduced-diameter portion length is l5 + l6. As an example, as the value of the ratio represented by (inlet inner diameter / reduced-diameter portion length), for example, a range of 1.5 to 4.1, preferably 1.5 to 3.9 can be selected. Furthermore, in order to suppress the length at the connection portion of the pipe bodies 1A, 1A and suppress the occurrence of cavitation, it is desirable to adjust the dimensions of each part as described below.

[0051] The possibility of cavitation occurring can be grasped by the cavitation coefficient Ca which can be expressed by the following formula (4) described below. Ca = (P - Pv) / (1 / 2)ρu 2 …Formula (4) However, in formula (4), P: absolute pressure (Pa), Pv: vapor pressure (Pa), (1 / 2)ρu 2 : representative pressure (dynamic pressure) (Pa), ρ = density of fluid (kg / m3 ), where u = representative velocity of the flow (m / s). Regarding the cavitation coefficient, it is preferable to adopt a range of 2.5 to 3.5, based on the test results shown in the examples described later. Within this range, a cavitation coefficient of 2.9 to 3.1 can also be adopted.

[0052] By adopting the extension connection structure shown in Figure 1 and using various sizes as described above, the risk of cavitation is low, and a compact connection structure can be achieved by using a short reduced-diameter section 2C. Furthermore, as shown in Figure 1, the reducer pipe 2 also functions as part of the joint when connecting pipe 1 to other pipes 1 with an electrofusion joint 3.

[0053] <Second Embodiment> Figure 4 shows a second embodiment of a reducer pipe (joint pipe) used integrated with the main piping body 1A. In the second embodiment, the shape and dimensional relationship of the outer diameter and inner diameter of the reducer pipe 20 are the same as those of the reducer pipe 2 in the first embodiment. The structure in which the reducer pipe 20 is integrated with the end of the piping body 1A is also the same as in the first embodiment. The differences between the reducer tube 20 of the second embodiment and the previous reducer tube 2 are as follows: While the previous reduced diameter portion 2C had an inclined surface 14 with an S-shaped cross-sectional contour having a concave curve 12 and a convex curve 13 on its inner surface, the second embodiment has an inclined surface 15 that can be represented as a straight line when viewed in the longitudinal cross-section shown in Figure 4.

[0054] This inclined surface 15 refers to an inclined surface in the reduced diameter section 2C where the rate at which the inner surface narrows from the large diameter section 2A side to the small diameter section 2B side is constant. The inner surface inclination angle θ of the reduced diameter portion of the inclined surface 15 in the reducer tube 2 of the second embodiment is set in the same way as the inner surface inclination angle θ of the reduced diameter portion of the inclined surface 14 in the first embodiment. Furthermore, the dimensions of the large-diameter portion 2A, the small-diameter portion 2B, and the reduced-diameter portion 2C described in the first embodiment can also be applied to the structure of the second embodiment.

[0055] <Third Embodiment> Figure 5 is a side view showing a pipe joint structure of a third embodiment in which a metal pipe, which integrally includes a reducer pipe having a large diameter section, a small diameter section, and a reduced diameter section, is connected to other pipes. In the third embodiment, a reducer pipe 31 is integrated with one end and the other end of a piping body 30 made of metal pipe. The reducer pipe 31 has a large diameter section 31A, a small diameter section 31B, and a reduced diameter section 31C that are substantially the same shape as the large diameter section 2A, small diameter section 2B, and reduced diameter section 2C shown in Figure 2. The large-diameter portion 31A differs from the large-diameter portion 2A of the first embodiment in that it is made of metal, and the metal large-diameter portion 31A is integrated with the metal pipe body 30.

[0056] The difference between the reduced diameter portion 31C and the reduced diameter portion 2C of the first embodiment is that it is made of metal and does not have a chamfered portion 2e. An inclined surface equivalent to the S-shaped cross-sectional contour inclined surface 14 formed on the reduced diameter portion 2C is formed on the inner surface of the reduced diameter portion 31C, but the inclined surface is not shown in Figure 5. Alternatively, the inclined surface formed on the inner surface of the reduced diameter portion 31C may be an inclined surface equivalent to the inclined surface 15 used in the second embodiment. The small-diameter portion 31B has a shape that is almost identical to the small-diameter portion 2B of the first embodiment, except that it is made of metal. The difference between the small-diameter portion 31B and the small-diameter portion 2B of the first embodiment is that a groove is formed on the outer circumference of the small-diameter portion 31B, and a ring-shaped sealing member 33 is wound along the groove. The sealing member 33 may be installed so as to be in contact with the reduced diameter portion 31C. Furthermore, there may be one or more sealing members 33, or two or more.

[0057] In the third embodiment, the piping body 30 equipped with the reducer pipe 31 can be used as a connecting fitting for a connecting pipe (other piping) 35 with the same outer diameter as the piping body 30. Since the inner diameter of the connecting pipe 35 is approximately equal to the outer diameter of the small-diameter section 31B, the main piping body 30 can be connected to the connecting pipe 35 via the reducer pipe 31 by inserting the small-diameter section 31B into the connecting pipe 35. Figure 6 shows the connection state of the connecting pipes 35, 35 to the main piping body 30. Furthermore, since both the reducer pipe 31 and the connecting pipe 35 are made of metal, the outer circumference of the butt joint portion of the reducer pipe 31 and the connecting pipe 35 can be integrated by joining means such as welding, as shown in Figure 6. Figure 6 shows the welded portion 36 formed at the butt joint portion of the reducer pipe 31 and the connecting pipe 35.

[0058] Assuming the extension connection structure shown in Figure 6 is adopted, the connection is made via a reduced-diameter section 31C with the same structure as in the first embodiment, thus reducing the risk of cavitation. Furthermore, because the reduced-diameter section 31C is short and compact, a compact connection can be made via the short reduced-diameter section 31C. As shown in Figure 6, the reducer pipe 31 functions as a pipe joint when connecting one connecting pipe 35 to another connecting pipe 35.

[0059] <Fourth Embodiment> Figure 7 shows a pipe joint structure using the piping of the fourth embodiment, in which the reducer pipe is provided only at one end of the main pipe body. In the fourth embodiment, there is a pipe body 40 that has the same structure as the pipe body 30 shown in the third embodiment, but only at one end. That is, one end of the pipe body 40 has a reducer pipe 41 having a large diameter section 41A, a small diameter section 41B, and a reduced diameter section 41C that have the same structure as the large diameter section 31A, small diameter section 31B, and reduced diameter section 31C of the third embodiment. The other end of the pipe body 40 does not have a large diameter section, a reduced diameter section, or a small diameter section, and only an opening is formed there. Therefore, by preparing multiple pipe bodies 40 and inserting the small-diameter portion 41B at one end of a pipe body 40 into the opening at the other end of another pipe body 40, multiple pipe bodies 40 can be joined together as shown in Figure 7.

[0060] Assuming the extension connection structure shown in Figure 7 is adopted, the connection is made via a reduced-diameter section 41C with the same structure as in the first embodiment, thus reducing the risk of cavitation. Furthermore, because the reduced-diameter section 41C is short and compact, a compact connection can be made via the short reduced-diameter section 41C. As shown in Figure 7, the reducer pipe 41 functions as a pipe joint when connecting one pipe body 40 to another pipe body 40.

[0061] (Application) The following describes an example of the use of the reducer pipe 2 (piping 1) shown in the first embodiment. Note that the reducer pipes (piping) shown in the second to fourth embodiments can also be used for similar purposes. However, the uses are not limited to the following.

[0062] Reducer pipe 2 (piping 1) may be used in piping for water, sewage, gas, gasoline, rainwater, factory wastewater, etc., and its use is not particularly limited. Furthermore, reducer pipe 2 (pipe 1) can be used in newly installed piping or as a pipe replacement pipe. In particular, when replacing a pipeline by inserting a new pipe into an existing pipe, the new pipe will have a smaller flow path cross-sectional area than the existing pipe, which may lead to a decrease in flow rate. However, by using reducer pipe 2, even if the flow path cross-sectional area is reduced, the probability of cavitation occurrence can be reduced, and the flow rate is less likely to decrease. Furthermore, while the joints 3 connecting the newly installed pipes may include, for example, electrofusion joints in the case of polyolefin pipes, the outermost diameter of the joint 3 tends to be larger because it requires terminals, which sometimes necessitates selecting a smaller diameter pipe for the new installation. However, by using a reducer pipe 2, the joint 3 is installed in the small-diameter section 2B, allowing the use of a joint 3 with an outer diameter approximately equal to that of the new pipe (the outer diameter of the large-diameter section 2A). Therefore, the reduction in the cross-sectional area of ​​the flow path of the new pipe compared to the existing pipe can be further reduced, enabling pipeline renewal while maintaining drainage capacity. The joint 3 may be any of the following: electrofusion joints, flanges, TS joints, mechanical joints, etc. The following is an example of a specific usage scenario for reducer pipe 2 (piping 1).

[0063] (Piping system) Figure 8 shows a cross-section of an existing pipe (existing conduit) 51 buried underground, and also shows a state in which a new piping system 52 has been formed inside the existing pipe 51 as a rehabilitation conduit along its length. In Figure 8, the area comprising the piping system 52 has an inlet vertical hole 53 and an outlet vertical hole 54 formed by excavating the ground 57 beneath the surface 56 at predetermined intervals. In addition, an additional inlet vertical hole 55 is formed to the side of the inlet vertical hole 53 shown in Figure 8, in an area other than the area between the inlet vertical hole 53 and the outlet vertical hole 54.

[0064] Figure 8 is a cross-sectional view of the pipe system 52 formed inside the existing pipe 51. The rehabilitation work can be completed by backfilling the inlet vertical hole 53, the outlet vertical hole 54, and the additional inlet vertical hole 55 from the state shown in Figure 8. Alternatively, after forming the pipe system 52 inside the existing pipe 51, a filler such as mortar may be used to fill the gaps inside the existing pipe 51, or the rehabilitation work can be completed by backfilling the inlet vertical hole 53, the outlet vertical hole 54, and the additional inlet vertical hole 55 from the state shown in Figure 8 without filling the gaps. The piping system 52 is constructed by joining together multiple pipes 1. For example, in the joined pipes 1, 1 shown in the first embodiment, their ends are joined together via electrofusion joints (joints) 3. That is, the piping system 52 comprises multiple pipes 1 and multiple electrofusion joints 3.

[0065] The piping system 52 is constructed by connecting multiple pipes 1 with multiple electrofusion joints 3 (i.e., by EF connections). The piping system 52 is made of a thermoplastic resin such as a polyolefin resin, with polyethylene being a typical example. By forming the piping system 52 with a thermoplastic resin such as a polyolefin resin, for example, it is possible to ensure the weight reduction and durability of the pipeline.

[0066] The piping system 52 is formed along its entire length (pipe length) L0 in the axial direction of the pipe. The total length L0 of the piping system 52 may be, for example, 50m or less, 100m or less, or longer than 100m. Alternatively, the total length L0 of the piping system 52 may be, for example, 10m or more.

[0067] Here, as shown in Figure 8, the inner diameter of the piping system 52 (pipe 1) is inevitably smaller than the inner diameter of the existing pipe 51. However, considering the current situation at sites where existing pipes 51 are being refurbished, existing pipes 51 are 30 to 50 years old, and in Japan today, when comparing the population 30 to 50 years ago with the current population, the vast majority of sites have a smaller current population. Considering this, it is generally considered that there are no problems in applying the piping system 52, even if the flow rate decreases slightly due to the smaller inner diameter of the piping system 52. Here, it is preferable that the reduction in diameter, expressed by the relationship (outer diameter of pipe 1 / inner diameter of existing pipe 51), is 35% or less. By maintaining this relationship, the largest possible flow rate can be secured in the piping system 52.

[0068] For example, the nominal diameter of pipe 1 may be one size smaller or more than the nominal diameter of the existing pipe 51. For example, the relationship between the nominal diameter of pipe 1 and the nominal diameter of the existing pipe 51 may be as shown in Table 1 below.

[0069] [Table 1]

[0070] Table 1 shows the relationship between the nominal diameters of pipe 1 and the existing pipe 51. The column headers in the top row of Table 1 indicate the diameter of the existing pipe 51 (existing pipe). For example, the column header "Existing Pipe 100" means that the nominal diameter of the existing pipe 51 is 100A. The "~" in the column header "Existing Pipe 350~" indicates "or greater," meaning that the nominal diameter of the existing pipe 51 is 350A or greater. The column headers in the leftmost column of Table 1 indicate the diameter of pipe 1. As mentioned earlier, pipe 1 consists of a main pipe body 1A (large diameter section 2A) and a small diameter section 2B. For example, the column headers "PinP" and "75×50" indicate that the nominal diameter of the main pipe body 1A (large diameter section 2A) of pipe 1 is 75A, and the nominal diameter of the small diameter section 2B is 50A. In Table 1, the "○" and "×" symbols in cells other than the item names (excluding the topmost row and the leftmost column) indicate whether pipe 1 in the row where the cell is located is applicable to the existing pipe 51 indicated by the item name in the column where the cell is located. "○" indicates that pipe 1 can be applied to the corresponding existing pipe 51, while "×" indicates that pipe 1 cannot be applied to the corresponding existing pipe 51.

[0071] As shown in Table 1, for example, if the nominal diameter of the existing pipe 51 is 100A, then pipe 1 can be applied if the nominal diameter of the pipe body 1A of pipe 1 is 75A. On the other hand, if the nominal diameter of the existing pipe 51 is 100A, then pipe 1 cannot be applied if the nominal diameter of the pipe body 1A of pipe 1 is 100A or greater (100A, 150A, 200A). Furthermore, for example, if the nominal diameter of the existing pipe 51 is 350 or more (350A or larger), then pipe 1 can be applied regardless of whether the nominal diameter of the pipe body 1A of pipe 1 is 75A, 100A, 150A, or 200A.

[0072] As shown in Figure 8, the pipe 1 may also be provided with a covering layer 58. The covering layer 58 is provided, for example, in the central part (pipe body 1A) in the pipe axis direction (length direction) of the pipe 1. The covering layer 58 is provided so as not to cover the aforementioned dashed line 6, leaving the dashed line 6 exposed. The covering layer 58 is provided so as not to cover both ends of the pipe 1. The outer surfaces of both ends of the pipe 1 are exposed. The pipe 1 has exposed portions at both ends. Here, the predetermined ratio B / A of (length of exposed portion B in the pipe 1) to (length A of the pipe 1) may be 5% or more and 20% or less. Also, the predetermined ratio B / C of (length B of exposed portion B in the pipe 1) to (length C of the covering layer 58) may be 4% or more and 20% or less.

[0073] Here, the thickness of the coating layer 58 may be, for example, 5 mm or less. By keeping the thickness of the coating layer 58 to 5 mm or less, it is possible to suppress, for example, the bending of the pipe 1 and contact with the existing pipe 51 (see Figure 8).

[0074] (Evaluation device for piping systems) Next, the piping system evaluation device 200 will be described with reference to Figures 9 to 11. Hereafter, the piping system evaluation device 200 may be abbreviated as "evaluation device 200".

[0075] Figure 9 is a block diagram showing the evaluation device 200 for the piping system. The piping system evaluation device 200 shown in Figure 9 evaluates whether drainage is possible through the piping system 52. In this embodiment, by determining the specifications of the various piping components used in the piping system 52 in such a way that good evaluation results can be obtained by the evaluation device 200, the piping system 52 can be given good drainage performance.

[0076] The evaluation device 200 may be, for example, a personal computer, a smartphone, or a tablet terminal. The function of the evaluation device 200 is realized by installing an evaluation application program that corresponds to the function of evaluating whether drainage by the piping system 52 is possible or not. The evaluation application may be configured by setting calculation formulas and macros in, for example, spreadsheet software, or it may be a dedicated application created to correspond to the drainage performance evaluation function of the piping system 52.

[0077] When designing the piping system 52, the user uses the evaluation device 200 to evaluate whether drainage is possible through the piping system 52 during the design phase. To evaluate the feasibility of drainage through the piping system 52, the user operates the evaluation device 200 to launch the evaluation application. The operation of the evaluation device 200 described below is performed while the evaluation application is running.

[0078] The user operates the evaluation device 200 on which the evaluation application runs, and displays a screen (calculation information input screen) for inputting information used for calculations for evaluation (calculation information) on the output unit 203 of the evaluation device 200.

[0079] As shown in Figure 9, the evaluation device 200 includes a communication unit 201, an input unit 202, an output unit (display unit) 203, a storage unit 204, and a control unit 205.

[0080] The communication unit 201 is a communication device. The communication unit 201 may be configured, for example, as a network interface. The communication unit 201 communicates information with other devices via the network in accordance with the control of the control unit 205. The communication unit 201 may be a device that performs wireless communication or a device that performs wired communication.

[0081] The input unit 202 is configured using existing input devices such as a keyboard, pointing device (mouse, tablet, etc.), buttons, or touch panel. The input unit 202 is operated by the user when inputting user instructions to the evaluation device 200. The input unit 202 may also be an interface for connecting the input device to the evaluation device 200. In this case, the input unit 202 inputs the input signal generated in the input device in response to the user's input to the evaluation device 200. The input unit 202 may also be configured using a microphone and a speech recognition device. In this case, the input unit 202 acquires the acoustic signal generated by the user's speech, performs speech recognition on the words spoken by the user, and inputs the recognized string information to the evaluation device 200. The speech recognition processing may be performed by the control unit 205. The input unit 202 may be configured in any way that allows user instructions to be input to the evaluation device 200.

[0082] The output unit 203 outputs information in a format that is recognizable to the user. The output unit 203 may be an image display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display. The output unit 203 may also be an interface for connecting an image display device to the evaluation device 200. In this case, the output unit 203 generates a video signal for displaying image information and outputs the video signal to the image display device connected to it. The output unit 203 may also be a device that outputs sound, such as a speaker. The output unit 203 may also be an interface for connecting an audio output device such as a speaker or headphones to the evaluation device 200. In this case, the output unit 203 generates an audio signal for reproducing audio information and outputs the audio signal to the audio output device connected to it. The output unit 203 may also be configured as a touch panel integrated with the input unit 202.

[0083] The storage unit 204 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The storage unit 204 stores information used by the control unit 205. The storage unit 204 stores information necessary when the control unit 205 performs processing.

[0084] The control unit 205 comprises an acquisition unit 206, a search unit 207, and a display control unit 208. The control unit 205 is configured using a processor such as a CPU (Central Processing Unit) and memory (main memory). The control unit 205 functions as the acquisition unit 206, search unit 207, and display control unit 208 when the processor executes a program. Note that all or part of the functions of the control unit 205 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), or FPGA (Field Programmable Gate Array). The above program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor memory devices (e.g., SSDs: Solid State Drives), as well as storage devices such as hard disks and semiconductor memory devices built into computer systems. The above program may be transmitted via a telecommunications line.

[0085] The control unit 205 may execute an application installed on the evaluation device 200, for example. A specific example of such an application is an application provided to the evaluation device 200 as a dedicated application for the piping system 52. Another specific example of such an application is a web browser application. Such an application may be pre-installed on the evaluation device 200, or it may be downloaded each time a judgment process is performed. For example, if it is implemented as a web browser application, the evaluation device 200 may download and execute the application from a device specified by the web server (for example, the web server itself or another server) when the evaluation device 200 connects to a specific web server. The control unit 205 operates according to the program of the application being executed. The acquisition unit 206, search unit 207, and display control unit 208, which constitute the control unit 205, will be explained in detail later.

[0086] Figure 10 shows a schematic diagram of an example hardware configuration of the piping system evaluation device 200. As shown in Figures 9 and 10, the piping system evaluation device 200 comprises a processor 211, main memory 212, communication interface 213, auxiliary storage device 214, input / output interface 215, and internal bus 216. The processor 211, main memory 212, communication interface 213, auxiliary storage device 214, and input / output interface 215 are connected to each other via the internal bus 216 so as to be able to communicate with each other. For example, the communication unit 201 may be configured using the communication interface 213. For example, the storage unit 204 may be configured using the auxiliary storage device 214. In addition, the control unit 205 may be configured using the processor 211 and the main memory 212.

[0087] (Configuration of the control unit) The acquisition unit 206, search unit 207, and display control unit 208, which constitute the control unit 205, will be described below. As shown in Figure 9, when the piping system evaluation device 200 evaluates whether drainage is possible through the piping system 52, the user inputs the information necessary to evaluate the feasibility of drainage into the input unit 202 as instructions. Examples of this type of information include: [1] the source pressure (internal pressure) of the piping system 52, [2] the flow rate of the piping system 52, and [3] an indicator representing the piping system 52.

[0088] The indicators for the piping system 52 described in [3] above are, for example, information indicating the structure of the piping system 52. The indicators for the piping system 52 described in [3] above include, for example, at least one of the indicators for the piping 1 described in [3-1] above, the total length of the piping system 52 described in [3-2] above, and the height difference of the piping system 52 described in [3-3] above. The indicators for the piping 1 described in [3-1] above are, for example, information necessary to identify the type of piping 1 described in [3-1] above. The indicators for the piping 1 described in [3-1] above include, for example, the diameter (size) of the piping 1, the length of the piping 1, or the part number of the piping 1 described in [3-1] above. Furthermore, not all of the information necessary to evaluate whether or not drainage is possible is input from the input unit 202. For example, even if the information is necessary to evaluate whether or not drainage is possible, fixed values ​​may be stored in the storage unit 204.

[0089] The acquisition unit 206 acquires information necessary to evaluate whether drainage is permitted or not, which is input to the input unit 202, such as [1] the main pressure of the piping system 52, [2] the flow rate of the piping system 52, and [3] an index indicating the piping system 52. In addition to the information input to the input unit 202, or in lieu of the aforementioned information, the acquisition unit 206 may acquire information necessary to evaluate whether drainage is permitted or not from the storage unit 204.

[0090] Based on the information acquired by the acquisition unit 206, the search unit 207 searches for an indicator indicating whether drainage by the piping system 52 is possible using an evaluation application program that can calculate pressure loss, etc. The evaluation application program that calculates pressure loss, etc. is a generally known calculation formula. The evaluation application program that calculates pressure loss, etc. is pre-installed in the search unit 207. Examples of the calculation formula include, but are not limited to, the Hazen-Williams formula shown in equations (4) and (5) below. V = 0.35464·C·d 0.63 ·I 0.54 …(4) Q = 0.27853·C·d 2.63 ·I 0.54 …(5) Here, V: average flow velocity (m / sec), C: velocity coefficient (=140), d: pipe diameter (m), I: hydraulic gradient, Q: flow rate (m 3 ( / sec)

[0091] An indicator of whether drainage is possible by the piping system 52 described above [4] is at least one of the following [5] and [6]. [5] An indicator that directly shows whether drainage is possible by the piping system 52. [6] An indicator that indirectly shows whether drainage is possible by the piping system 52.

[0092] The indicator that directly indicates whether drainage by the piping system 52 [5] is possible is, for example, binary information such as "OK" or "NG". This indicator may be searched by the search unit 207 based on, for example, an indicator that indirectly indicates whether drainage by the piping system 52 [6] described later is possible.

[0093] An indicator that indirectly shows whether drainage is possible by the piping system 52 [6] is, for example, at least one of the following [6-1] to [6-5]. [6-1] Predicted flow velocity in piping system 52 [6-2] Predicted head loss in piping system 52 [6-3] Predicted flow rate in piping system 52 [6-4] Equivalent pipe length of piping system 52 [6-5] Indicators showing the conditions necessary for drainage by the piping system 52 to be possible.

[0094] The predicted flow velocity in the piping system 52 described in [6-1] above is, for example, the result of a search (calculation) performed by the search unit 207 based on the information acquired by the acquisition unit 206. For example, if the entity that determines whether or not drainage by the piping system 52 is possible is the user (human), the user can determine whether or not drainage by the piping system 52 is possible by determining whether or not this predicted flow velocity is an acceptable flow rate. The acceptable flow velocity may, for example, be set by the user as appropriate. From the above, it can be said that the predicted flow velocity in the [6-1] piping system 52 functions as an indirect indicator of whether or not drainage by the [6] piping system 52 is possible. Similarly, the predicted head loss in the [6-2] piping system 52, the predicted flow rate in the [6-3] piping system 52, and the equivalent pipe length of the [6-4] piping system 52 also function as indirect indicators of whether or not drainage by the [6] piping system 52 is possible. Note that the equivalent pipe length in [6-4] is, for example, the length of a straight pipe that would produce an equivalent pressure loss if the piping system 52 were converted to a straight pipe.

[0095] The indicators that show the conditions necessary for drainage by the piping system 52 described in [6-5] above include, for example, the number of pipes 1 and electrofusion joints 3 required for the piping system 52, the cost of the pipes 1 and electrofusion joints 3, and the weight of the pipes 1 and electrofusion joints 3. For example, if the entity that determines whether or not drainage by the piping system 52 is possible is a user (human), the user can determine whether or not drainage by the piping system 52 is possible by determining whether or not these kinds of values ​​are acceptable. Therefore, the indicators that show the conditions necessary for drainage by the piping system 52 described in [6-6] also function as indicators that indirectly show whether or not drainage by the piping system 52 is possible.

[0096] The display control unit 208 (output control unit) displays (outputs) an indicator found by the search unit 207, which indicates whether or not drainage by the piping system 52 is possible, on the output unit 203. The output unit 203 may display the indicator found by the search unit 207 in the form of a graph, a table, or the like.

[0097] Here, the acquisition unit 206 may acquire an index indicating multiple types of piping systems 52 as an index indicating the [3] piping system 52. The search unit 207 may also search for an index indicating whether drainage is possible using each of the multiple types of piping systems 52 as an index indicating whether drainage is possible using the [4] piping system 52. In this case, multiple types of piping systems 52 can be compared, and a piping system 52 suitable for construction can be selected from among the compared piping systems 52. When comparing multiple types of piping systems 52, for example, the output unit 203 may display the multiple types of piping systems 52 so that they can be compared.

[0098] Next, a specific example of evaluating whether drainage is possible through the piping system 52 using the piping system evaluation device 200 will be explained with reference to Figure 11. Figure 11 shows an example of the display of the evaluation of the piping system 52 discovered by the piping system evaluation device 200.

[0099] The first region R1, located at the top of the display region R of the output unit 203 shown in Figure 11, indicates the preconditions. These preconditions are, for example, the conditions for evaluating whether drainage by the piping system 52 is possible.

[0100] In the upper left region R1-1 of the first region R1, the water pressure is indicated as 0.5 MPa, the flow velocity as 0.5 m / s, and the section as 50 m. Of these, the water pressure corresponds to the initial pressure (internal pressure) of the [1] piping system 52, and the flow velocity corresponds to the flow rate of the [2] piping system 52. Furthermore, the section is the section of the piping system 52 and corresponds to the total length of the [3-2] piping system 52, which is an indicator of the [3] piping system 52.

[0101] In the lower left region R1-2 of the first region R1, the preconditions for the joint shape of the reducer pipe 2 are shown. The preconditions for the joint shape of the reducer pipe 2 correspond to the index for [3-1] piping 1 among the index for [3] piping system 52. In the illustrated example, it is stated that the processed joint shape of the reducer pipe 2 is 30°, and this angle of 30° represents the inner surface inclination angle θ of the reduced diameter portion mentioned above.

[0102] In the right-hand region R1-3 of the first region R1, a diagram is displayed that visualizes at least some of the aforementioned preconditions in a way that makes them recognizable as the piping system 52. The string "PinP" in the right-hand region R1-3 is an abbreviation for pipe-in-pipe and indicates the piping system 52.

[0103] The user inputs the various preconditions for the piping system 52 described above into the evaluation device 200 via the input unit 202. For example, conditions other than the various preconditions described above may be stored as fixed values ​​in the storage unit 204. In other words, the evaluation device 200 may treat some of the indicators (information) necessary for evaluation as variables and the remainder as constants, and may receive the variable information as input from the input unit 202.

[0104] The evaluation device 200 (display control unit 208) displays the evaluations found based on the preconditions on the output unit 203. In the display area R shown in Figure 11, the evaluation device 200 (display control unit 208) displays the preconditions in the upper first area R1, as described above, and displays the found evaluations in a table in the lower second area R2. By outputting both the preconditions and the evaluations to the output unit 203 in this way, the correspondence between the preconditions and the evaluations becomes easier to understand.

[0105] Here, as shown on the right side of the table in the second region R2, the display control unit 208 displays the predicted flow velocity in the piping system 52 (the column with the heading "Flow velocity (m / s)" in the table) and the predicted head loss in the piping system 52 (the column with the heading "Head m (10kPa)" in the table) as indicators of whether drainage by the piping system 52 is possible. Each of these indicators is searched (calculated) by the search unit 207.

[0106] In this embodiment, the display control unit 208 displays an index in a comparable manner indicating whether drainage is possible using each of the multiple types of piping systems 52. In the illustrated example, for each diameter of the existing pipe 51 (the column with the heading "Existing Pipe" in the table), the following ~ <c>The display control unit 208 displays an indicator for the three types of piping systems 52 (the column with the heading "PinP section" in the table) that shows whether or not drainage is possible using the [4] piping system 52. < / c> Piping system 52 is method A: Conventional construction method Piping system 52 is type B: In the case of a 5.0m dedicated pipe for piping system 52. <c>Piping system 52 is type C: In the case of a 2.5m dedicated pipe for piping system 52

[0107] Here, the display control unit 208 controls the piping system 52< / c> ~ <c>The diameter of the piping system 52 is displayed along with each method. These indicators correspond to the indicators that show the piping system 52. For example, Method B: The dedicated pipe of the piping system 52 is 5.0m, which indicates that there is only one type of pipe 1 (dedicated pipe) with a length of 5.0m. In this embodiment, the display control unit 208 displays an index indicating the piping system 52, along with the percentage change in area between the existing piping 51 and the piping system 52 (the column with the heading "Area Change" in the table). However, the percentage change in area does not need to be displayed.

[0108] The following describes a specific example of how the table for the second domain, R2, is displayed. For example, as shown in the top row of the table in the second region R2, the display control unit 208 displays the area changes, flow velocities, and water heads for each of the following methods for an existing pipe (existing pipe) 51 with a diameter of 100: Method A: Conventional method (diameter 50), Method B: Dedicated pipe 5.0m of the piping system 52 (diameter 75), and Method C: Dedicated pipe 2.5m of the piping system 52 (diameter 75), in a comparable manner. For example, as shown in the upper middle section of the table in the second region R2, the display control unit 208 displays the area changes, flow velocities, and water heads for each of the following methods for an existing pipe 51 with a diameter of 150: Method A: Conventional method (diameter 75), Method B: Dedicated pipe 5.0m of the piping system 52 (diameter 100), and Method C: Dedicated pipe 2.5m of the piping system 52 (diameter 100), in a comparable manner.

[0109] For example, as shown in the lower middle section of the table in the second region R2, the display control unit 208 displays the area change, flow velocity, and water head for three methods in an existing pipe 51 with a diameter of 200: Method A: Conventional method (diameter 100), Method B: Dedicated pipe 5.0m of the piping system 52 (diameter 150), and Method C: Dedicated pipe 2.5m of the piping system 52 (diameter 150). For example, as shown in the bottom row of the table in the second region R2, the display control unit 208 displays the area change, flow velocity, and water head for three methods in an existing pipe 51 with a diameter of 300: Method A: Conventional method (diameter 150), Method B: Dedicated pipe 5.0m of the piping system 52 (diameter 200), and Method C: Dedicated pipe 2.5m of the piping system 52 (diameter 200), in a comparable manner.

[0110] Here, [4] an indicator showing whether drainage by the piping system 52 is possible, in this embodiment, [6-1] the predicted flow velocity in the piping system 52, and [6-2] the predicted head loss in the piping system 52 are searched by the search unit 207, for example, based on the various preconditions described above.

[0111] In this way, the piping system evaluation device 200 displays the evaluation of the searched piping system 52 along with the preconditions as Figure 11 on the output unit 203. For example, the user selects a piping system 52 that is compatible with the existing piping 51 based on the preconditions and table in Figure 11 displayed on the output unit 203.

[0112] The piping system evaluation device 200 according to the first embodiment described above comprises an acquisition unit 206 and a search unit 207. The acquisition unit 206 acquires the source pressure of the piping system 52, the flow rate of the piping system 52, and an indicator representing the piping system 52. The search unit 207 searches for an indicator indicating whether drainage by the piping system 52 is possible based on the information acquired by the acquisition unit 206. As a result, a compact and easy-to-install piping system 52 can be obtained based on the information obtained from the piping system evaluation device 200.

[0113] Furthermore, the indicator for the piping system 52 includes at least one of the following: an indicator for pipe 1, the total length of the piping system 52, and the height difference of the piping system 52. This allows the search unit 207 to appropriately search for an indicator that shows whether or not drainage is possible through the piping system 52. An indicator of whether or not drainage by the piping system 52 is possible includes, for example, at least one of a direct indicator and an indirect indicator. This allows the search unit 207 to appropriately search for an indicator of whether or not drainage by the piping system 52 is possible.

[0114] The acquisition unit 206 acquires an index indicating multiple types of piping systems 52, and the search unit 207 searches for an index indicating whether drainage is possible using each of the acquired types of piping systems 52. Therefore, multiple types of piping systems 52 can be compared, and the piping system 52 appropriate for construction can be selected from among the compared piping systems 52. This allows the search unit 207 to appropriately search for an index indicating whether drainage is possible using the piping system 52.

[0115] The piping system evaluation device 200 further includes a display control unit 208. The display control unit 208 displays an indicator found by the search unit 207, which indicates whether or not drainage by the piping system 52 is possible, on the output unit 203. The output unit 203 may display the indicator found by the search unit 207 in the form of a graph, a table, or the like.

[0116] Furthermore, when comparing multiple types of piping systems 52, for example, the system may display the information in a way that allows for comparison of multiple pipe types. This allows for proper confirmation of the indicator showing whether drainage is possible using the piping system 52 discovered by the search unit 207.

[0117] (Calculation device) Next, the calculation device 300 will be explained with reference to Figure 12. Figure 12 is a block diagram of the calculation device 300. The calculation device 300 shown in Figure 12 calculates at least one of the time required and the cost of constructing the piping system 52. The calculation device 300 calculates at least one of the time required and the cost of constructing the piping system 52 based on, for example, the total length of the piping system 52. The calculation device 300 may also calculate at least one of the time required and the cost of constructing the piping system 52 based on, for example, the diameter (nominal diameter, outer diameter, inner diameter) of the pipe 1 in addition to the total length of the piping system 52.

[0118] The calculation device 300, like the evaluation device 200, may be, for example, a personal computer, smartphone, or tablet terminal. The function of the calculation device 300 is realized by installing a calculation application program that calculates at least one of the period and cost required for the construction of the piping system 52. The calculation application may be configured by setting calculation formulas and macros in, for example, spreadsheet software, or it may be a dedicated application. The hardware configuration of the calculation device 300 can be the same as that of the evaluation device 200, as shown in Figure 10.

[0119] As shown in Figure 11, the calculation device 300 comprises a communication unit 301, an input unit 302, an output unit (display unit) 303, a storage unit 304, and a control unit 305 as its functional configuration. These communication unit 301, input unit 302, output unit 303, storage unit 304, and control unit 305 share many similarities with the communication unit 201, input unit 202, output unit 203, storage unit 204, and control unit 205 of the evaluation device 200. In the following, these similarities will not be described, and the main differences will be described.

[0120] The control unit 305 comprises an acquisition unit 306, a calculation unit 307, and a display control unit 308. The acquisition unit 306, calculation unit 307, and display control unit 308 will be described below. When the calculation device 300 calculates at least one of the period and cost required for the construction of the piping system 52, the user inputs information necessary to calculate the period and cost into the input unit 302. This type of information includes the total length of the piping system 52 and the diameter of the pipes 1. Not all of the information necessary to calculate the period and cost is entered into the input unit 302. For example, even if the information is necessary to calculate the period and cost, fixed values ​​may be stored in the storage unit 304. This type of information includes information related to labor costs and the length of each pipe 1.

[0121] The acquisition unit 306 acquires information necessary for calculating the period and cost, such as the total length of the piping system 52 and the diameter of the pipe 1, which are input to the input unit 302. In addition to the information input to the input unit 302, or in lieu of the aforementioned information, the acquisition unit 306 may acquire information necessary for calculating the period and cost from the storage unit 304.

[0122] Based on the information acquired by the acquisition unit 306, the calculation unit 307 calculates at least one of the required period and cost for the construction of the piping system 52 using a calculation application program that can calculate the period and cost required for the construction of the piping system 52.

[0123] The display control unit 308 (output control unit) displays (outputs) at least one of the period and cost required for the construction of the piping system 52, which are calculated by the calculation unit 307, to the output unit 303. The output unit 303 may display the period and cost calculated by the calculation unit 307 in the form of a graph, table, or the like.

[0124] Here, we will explain an example of how the calculation unit 307 calculates the time and cost required for the construction of the piping system 52. In this embodiment, the calculation unit 307 calculates the number of work units required for the construction of the piping system 52 based on the total length of the piping system 52 and the diameter of the pipe 1. The method for calculating the number of units is stored, for example, in the storage unit 304. The calculation unit 307 calculates the manpower required for the construction of the piping system 52 based on the calculated number of units for each task. For example, the storage unit 304 stores the unit rates for each task, and the manpower required for each task is calculated by multiplying the number of units by the unit rates. The calculation unit 307 calculates the time and cost required for the construction of the piping system 52 based on the man-hours calculated for each task. For example, the calculation unit 307 receives the number of workers and the unit price per man-hour from the input unit 202, and calculates the time and cost required for the construction of the piping system 52 based on the received number of workers and unit price, and the man-hours calculated for each task.

[0125] Here, examples of the work involved in the construction of the piping system 52 include the following

[11] to

[18] . However, it is not necessary to consider all of these when calculating the time and cost required for the construction of the piping system 52. Also, when calculating the time and cost required for the construction of the piping system 52, other work may be considered instead of, or in addition to, the following

[11] to

[18] .

[0126]

[11] Cleaning work inside existing pipes

[12] Testing of simulated pipes

[13] Equipment installation and removal work

[14] Pipe lifting and installation work

[15] Pipe connection work

[16] Pipe insertion and pull-in work

[17] Pipe end treatment work

[18] Airtightness testing procedure

[0127]

[11] The existing pipe cleaning work is the work of cleaning the inside of the existing pipe 51 before installing the piping system 52 inside the existing pipe 51.

[12] The simulated pipe verification process involves passing a simulated pipe, which is a replica of the piping system 52, through the existing piping 51 before installing the piping system 52 inside the existing piping 51, in order to verify whether the pipes 1, etc., can actually pass through the existing piping 51.

[13] Equipment installation and removal work involves installing and removing equipment (for example, hoisting machines, etc.) necessary for the installation of the piping system 52.

[0128]

[14] The pipe suspension and installation work involves suspending the pipe 1 from a vertical hole and installing it in a connecting device (for example, an EF fusion splicer) for connecting pipes 1 within the vertical hole.

[15] The piping connection work is the work of connecting the pipes 1 installed on the connection device.

[16] The pipe insertion and pulling operation is the operation of inserting and pulling the pipe 1, which has been connected as described above in the vertical hole, into the existing pipe 51.

[0129]

[17] The pipe end processing work is the work of processing the pipe ends of the piping system 62 installed in the existing piping 51, for example, the work of cutting off the excess length at the pipe end of the piping system 62.

[18] The airtightness test is the process of testing the airtightness of the piping system 62.

[0130] In some of these tasks, for example, the number of units of work varies depending on the total length of the piping system 52.

[11] Cleaning work inside existing pipes

[12] Testing of simulated pipes

[14] Pipe lifting and installation work

[15] Pipe connection work

[16] Pipe insertion and pull-in work

[18] Airtightness testing procedure

[0131] Here, the relationship between the total length of the piping system 52 and the number of units for each operation may be stored, for example, in the memory unit 304. The calculation unit 307 may calculate the number of units for each operation based on this relationship and the total length assumed for the target piping system 52.

[0132] Of these tasks, for example, the number of units of work varies depending on the diameter of the piping system 52.

[12] Testing of simulated pipes

[14] Pipe lifting and installation work

[15] Pipe connection work

[16] Pipe insertion and pull-in work

[17] Pipe end treatment work

[18] Airtightness testing procedure

[0133] Here, the relationship between the diameter of pipe 1 and the number of units for each operation may be stored, for example, in the memory unit 304. The calculation unit 307 may calculate the number of units for each operation based on this relationship and the diameter of pipe 1 assumed in the target piping system 52.

[0134] The calculation device 300 estimates the number of units and man-hours for each individual task, as described above, and calculates the time and cost required for the construction of the piping system 52. The calculation device 300 may calculate at least one of the time and cost required for the construction of the piping system 52 based on both the total length of the piping system 52 and the diameter of the pipe 1, or it may calculate at least one of the time and cost required for the construction of the piping system 52 based on only one of the total length of the piping system 52 and the diameter of the pipe 1.

[0135] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

[0136] For example, the display control unit 208 may be omitted in the evaluation device 200. The search unit 207 may search for an index indicating whether drainage is possible using only one type of piping system 2. For example, the display control unit 308 may be omitted in the calculation device 300. The evaluation device 200 and calculation device 300 are not required.

[0137] Furthermore, it is possible to replace the components in this embodiment with well-known components as appropriate, without departing from the spirit of the present invention. [Examples]

[0138] A reducer pipe was prepared with a large diameter section of 75A (72.6 mm) as the inlet diameter and a small diameter section of 50A (50.7 mm) as the outlet diameter. Multiple reducer tubes were fabricated with the length of the reduced-diameter section formed between the large-diameter and small-diameter sections set to various values ​​as shown in Table 2 below, and the total length set to the values ​​shown in Table 2 below. As a diameter-reducing section, an S-shaped cross-sectional shape as shown in the vertical cross-section of Figure 1 was formed on the inner surface in Examples 1 to 3, and a straight (tapered) cross-sectional shape as shown in the vertical cross-section of Figure 4 was formed in Example 4, all having a constant inner surface inclination angle θ of the diameter-reducing section. In the comparative example, the end face of the small diameter section was formed perpendicular to the pipe axis. For each reducer pipe, the cavitation coefficient was measured and the water flow velocity (m / S) and the ratio of (inlet inner diameter / reduced diameter section length) at the time of cavitation generation were determined by water flow experiments.

[0139] In the pipe connection structure shown in Figure 1, where pipe bodies 1A and 1A are connected by an electrofusion joint, a water flow test was conducted in the direction indicated by arrow a, from the right pipe body 1A to the left pipe body 1A. Measurement plugs were attached to a position 2D (inlet inner diameter × 2) upstream and 6D (inlet inner diameter × 6) downstream of the measurement section (electrofusion joint), and the flow velocity, flow rate, and cavitation coefficient were measured. Table 2 below summarizes the test results when using a nominal diameter of 75A for the inlet and 100A for the outlet. In Table 2, "with bead" means that the pipe was fused to the straight pipe body with a reducer pipe, resulting in the formation of a bead at the fusion joint. The test was conducted without removing the bead. "Without bead" means that the pipe end of the straight pipe was thermally deformed to integrally form the reduced diameter section and the small diameter section.

[0140] [Table 2]

[0141] Based on the results shown in Table 2, it can be determined that the cavitation coefficient can be selected within the range of 2.0 to 3.5, and more specifically, it is desirable to select a range of 2.2 to 3.1. Furthermore, regarding compactness, the ratio expressed as (inlet inner diameter / reduced diameter length) should ideally be 1.5 or higher, with a range of 1.5 to 3.9 being selectable, and 3.0 or higher being considered more desirable. If a reducer tube having a large-diameter section, a small-diameter section, and a reduced-diameter section that meet these conditions is used, it is thought that a compact and easy-to-handle reducer tube with a low risk of cavitation can be provided. [Explanation of Symbols]

[0142] 1...Piping, 1A...Main pipe (straight pipe), 2...Reducer pipe (joint pipe, pipe fitting), 2A...Large diameter part, 2B...Small diameter part, 2C...Reduced diameter part, 14, 15...Slanted surface, 20...Reducer tube, 31...Reducer tube, 31A...Large diameter section, 31B...Small diameter section 31C...Reduced diameter section, 41...Reducer tube, 41A...Large diameter section, 41B...Small diameter section 41C...Reduced diameter part, θ…Inner inclination angle of the reduced diameter part, Ca... Cavitation coefficient.< / c>

Claims

1. A pipe having a small diameter section and a large diameter section, with a reduced diameter section between the small diameter section and the large diameter section, The angle at which the central axes of the small diameter portion, the large diameter portion, and the reduced diameter portion intersect the line segment connecting the boundary position between the small diameter portion and the reduced diameter portion as drawn when viewing the longitudinal cross-section of the small diameter portion, and the boundary position between the large diameter portion and the reduced diameter portion as drawn when viewing the longitudinal cross-section of the large diameter portion, is defined as the inner surface inclination angle θ of the reduced diameter portion. The length of the reduced diameter portion in the direction along the central axis is defined as the reduced diameter portion length. If the inner diameter at the boundary position of the large-diameter portion is defined as the inlet inner diameter, The ratio value expressed as (inlet inner diameter / reduced diameter section length) is 1.5 or greater. The cavitation coefficient is between 2.0 and 3.

5. Piping.

2. The inner surface inclination angle θ of the reduced diameter portion is 15 to 30°. The piping according to claim 1.

3. The cavitation coefficient is 2.2 to 3.

1. The piping according to claim 1.

4. The ratio value expressed as (inlet inner diameter / reduced diameter length) is in the range of 1.5 to 3.

9. The piping according to claim 1.

5. The inner circumferential contour of the reduced diameter portion, as drawn in the longitudinal section of the reduced diameter portion, is an S-shaped curve. The piping according to claim 1.

6. A straight pipe is connected to the aforementioned large-diameter section. The piping according to claim 1.

7. A bead is formed at the connection between the large-diameter portion and the straight pipe. The piping according to claim 6.

8. A pipe according to any one of claims 1 to 7, A piping system comprising a fitting connected to the aforementioned pipe.

9. An evaluation device for a piping system according to claim 8, An acquisition unit that acquires the source pressure of the piping system, the flow rate of the piping system, and an indicator representing the piping system, A piping system evaluation device comprising: a search unit that searches for an indicator indicating whether or not drainage is possible by the piping system based on the information acquired by the acquisition unit; and

Images