JP2004190815A - Piping support structure and support method - Google Patents

Abstract

An object of the present invention is to effectively prevent damage to a U-bolt when a continuous high-cycle vibration or the like is applied to the U-bolt supporting a pipe.
[Structure] A leg 5 of a U-bolt 4 supporting a pipe 1 is inserted into a bolt hole 3 provided in a mounting member 2, and a rear end 6a of a screw portion 6 formed in the leg 5 is piped from the bolt hole 3. The U bolt 4 is fastened with the nut 7 without projecting to the one side.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pipe supporting structure and a supporting method using a U-bolt, and more particularly, to a pipe supporting method that can be suitably applied when the U-bolt is subjected to a continuous high-cycle vibration or a continuous shear stress. It relates to the structure and the supporting method.
[0002]
[Prior art]
Many pipes are laid in various plants and facilities. Usually, these pipes are supported on mounting members such as building walls and structural frames using U-bolts. In other words, the pipe is supported by inserting the legs of the U-bolt supporting the pipe into the bolt holes formed in the mounting member and fastening nuts to the threaded portions formed on the pair of legs.
[0003]
Standards for supporting pipes with U bolts are specified in JIS. For example, “U-bolt for mounting steel pipes for ships” is specified in JIS F3022, and three types of A-type, B-type, and C-type are specified as a method of mounting a nut to the U-bolt. Here, the A type and the B type are applied to a nominal size of 100 mm or more, and the C type is applied to a nominal size of 90 mm or less.
[0004]
Type A is a method in which the leg of a U-bolt is inserted into the bolt hole of the mounting member, and the leg is fastened with nuts from both the piping side and the opposite side with the bolt hole in between. The U-bolt is inserted into the bolt hole of the mounting member, and the U-bolt is inserted into the bolt hole of the mounting member. And the legs are fastened with double nuts from the opposite side. In addition, it stipulates that a C-shape may be used especially in a place where vibration is severe.
[0005]
FIG. 2 is a cross-sectional view showing a C-shaped pipe support structure defined in JIS F3022. In FIG. 2, 1 is a pipe, 2 is a mounting member, 3 is a bolt hole provided on the mounting member, 4 is a U-bolt, 5 is a leg of the U-bolt 4, 6 is a screw provided on the leg 5, 6a is The rear end of the screw portion, 7 is a nut. As shown in the figure, in order to support the pipe 1 on the mounting member 2, first, the pipe 1 is gripped and supported by the U-shaped portion of the U bolt 4, and its leg 5 is inserted through the bolt hole 3 of the mounting member 2. Then, the nut 7 is double fastened to the screw portion 6 formed on the leg portion 5 from the side opposite to the pipe 1.
[0006]
[Problems to be solved by the invention]
However, in the piping support structure shown in FIG. 2, the rear end 6 a of the screw portion 6 formed on the leg portion 5 projects from the bolt hole 3 of the mounting member 2 toward the piping side. Therefore, when the U-bolt 4 is subjected to continuous high-cycle vibration or continuous shear stress from the pipe 1, the U-bolt 4 may be damaged by metal fatigue.
[0007]
Experiments have shown that when a U-bolt is subjected to sustained high-cycle vibrations or sustained shear stress in the Y and Z directions as shown by the arrows in FIG. It was confirmed that a load and a shear load were repeatedly applied, and they were concentrated on a portion where the leg 5 was in contact with the edge of the bolt hole 3 on the pipe side.
[0008]
Since the screw portion 6 is formed in the portion where the stress is concentrated as described above, it is presumed that the shaft diameter of the leg portion is reduced, and the leg portion is easily damaged due to the cutting effect. Therefore, an object of the present invention is to solve the above-mentioned problems in the conventional pipe support structure using U-bolts, and to provide a new pipe support structure and a new support method therefor.
[0009]
[Means for Solving the Problems]
The pipe supporting structure according to the present invention that solves the above-mentioned problem has a U-bolt leg supporting a pipe inserted into a bolt hole provided in a mounting member, and the U-bolt having a threaded portion formed in the leg. The rear end is fastened by a nut without protruding from the bolt hole to the pipe side (claim 1).
[0010]
According to the above support structure, the rear end of the threaded portion formed on the U bolt is prevented from protruding from the bolt hole toward the pipe when the nut is fastened. Therefore, since there is no threaded portion for reducing the diameter of the leg at the portion where the leg contacts the edge of the bolt hole on the pipe side, the durability of the leg can be improved.
[0011]
The above-mentioned effect is exhibited particularly when the U-bolt is in a situation where the U-bolt receives a continuous high-cycle vibration or a continuous shear stress from the pipeline (claim 2).
Here, high-cycle vibration means fatigue caused by continuous vibration caused by rotation of a rotating machine or vibration caused by fluid flow during operation of various plants.
[0012]
In addition, a pipe supporting method according to the present invention for solving the above-mentioned problems is characterized in that a leg of a U-bolt supporting a pipe is inserted into a bolt hole provided in a mounting member, and a rear end of a screw part formed in the leg is bolted. A nut is fastened to the leg of the U-bolt so as not to protrude from the hole toward the pipe (claim 3).
[0013]
In the pipe supporting method, the amount of the leg portion inserted into the bolt hole can be adjusted by interposing the lock nut when the U bolt is fastened with the nut (claim 4). By using such a lock nut, the insertion amount of the leg portion into the bolt hole can be set arbitrarily and easily.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a pipe support structure according to the present invention. In FIG. 1, 1 is a pipe, 2 is a mounting member, 3 is a bolt hole in the mounting member, 4 is a U-bolt, 5 is a leg of the U-bolt 4, 6 is a thread provided on the leg 5, 6a is a thread. The rear end 7 is a nut.
[0015]
In the support structure of FIG. 1, the screw portion 6 formed on the leg portion 5 extends from the inside of the bolt hole 3 to the side opposite to the pipe 1, so that the rear end 6 a of the screw portion 6 extends from the bolt hole 3. Does not protrude to the pipe 1 side. Therefore, as described above, the load applied from the pipe 1 to the leg portion 5 is concentrated on the portion where the screw portion 6 is not formed, and the durability of the leg portion 5 can be improved.
[0016]
That is, if the U-bolt 4 is subjected to sustained high-cycle vibration or sustained shear stress in the Y and Z directions as indicated by the arrows in FIG. A tensile load and a shear load are applied to the portion, and they concentrate on a portion where the leg 5 contacts the edge of the bolt hole 3 on the pipe 1 side. However, since the screw portion 6 is not formed at the contact portion, the substantial cross-sectional area of the leg 5 remains the original cross-sectional area, so that the load-bearing capacity does not decrease. The performance is improved.
[0017]
As shown in the figure, in order to support the pipe 1 on the mounting member 2, first, the leg 5 of the U bolt 4 supporting the pipe 1 is inserted into the bolt hole 3 provided in the mounting member 2, and a screw formed on the leg 5 is formed. The nut 7 is fastened to the leg 5 of the U-bolt 4 so that the rear end 6a of the portion 6 does not project from the bolt hole 3 toward the pipe.
When fastening the nut 7 to the leg 5, one or several spacers made of flat washers and spring washers or lock nuts 8 are interposed, so that the amount of insertion of the leg 5 into the bolt hole 3 can be arbitrarily set. It can be easily set.
[0018]
【Example】
Next, an experimental example on the strength of the U bolt in the pipe support structure according to the present invention shown in FIG. 1 will be described. The diameter D of the pipe 1 is 34 mm, the height h from the mounting member 2 to the center of the pipe 1 is D / 2 = 17 mm, the reaction force Rz applied to the U bolt from the pipe 1 in the Z direction is 48.0 Kg, and the reaction force in the Y direction is When the force Ry is 76.3 Kg, the excitation force (analysis value) Fz in the Z direction is 28.0 Kg, and the excitation force (analysis value) Fy in the Y direction is 35.0 Kg, the bending moment and stress in the U bolt 4 The degree is calculated as follows:
[0019]
(1) Bending moment of stress U bolt due to pipe reaction force M = Rz × h = 48.0 × 17 = 816.0 (Kg · mm)
U bolt bending stress degree σb = M / Z = 816.0 / 98.18 = 8.31 (Kg / mm ² )
Here, Z in the above equation is a bolt section modulus, and when the shaft diameter d2 of the bolt is 10 mm, Z = (π × d2 cube) / 32 = (π × 10 cube) /32=98.18 (Mm ³ ).
[0020]
U bolt tension T = Ry / 2 = 76.3 / 2 = 38.15 (Kg)
U bolt tensile stress degree σt = βk × (T / A1) = 2.64 × (38.15 / 55.1) = 1.83 (Kg / mm ² )
Here, A1 in the above equation is the cross-sectional area of the U bolt in the threaded portion, and when the bolt root diameter d1 is 8.376 mm, A1 = π × (square of d1 / 4) = π × (8.376 (2/4) = 55.1 (mm ² ).
[0021]
U bolt shear stress τ = Rz / A2 = 48.0 / 78.54 = 0.61 (Kg / mm ² )
Here, A2 in the above equation is the cross-sectional area of the U bolt, and when the shaft diameter d2 is 10 mm, A2 = π × (square of d2) / 4 = π × (square of 10) / 4 = 78. 54 (mm).
Synthetic stress degree σm = [square of (σb + σt) + square of 3 × τ] = 10.19 (Kg / mm ² )
[0022]
(2) Stress amplitude during vibration U bending moment of bolt M = Fz × h = 28.0 × 17 = 476.0 (Kg · mm)
U bolt bending stress degree σb = M / Z = 476.0 / 598.18 = 4.85 (Kg / mm ² )
U bolt tension T = Fy / 2 = 35.0 / 2 = 17.5 (Kg)
[0023]
U bolt tensile stress degree σt = βk × (T / A1) = 2.64 × (17.5 / 55.1) = 0.84 (Kg / mm ² )
U bolt shear stress τ = Fz / A2 = 28.0 / 78.54 = 0.36 (Kg / mm ² )
Synthetic stress degree σm = [square of (σb + σt) + square of 3 × τ] = 5.72 (Kg / mm ² )
[0024]
In each of the above equations, the stress level is the stress that the U bolt receives per unit cross-sectional area, so that the smaller the value, the better the durability.
Next, for comparison, with respect to the conventional pipe support structure shown in FIG. 2, the bending moment and the stress degree in the U bolt when the pipe reaction force and the vibration excitation force from the same pipe as in FIG. 1 are applied are as follows. Is calculated.
[0025]
(1) Stress due to pipe reaction force U Bending moment of bolt M = Rz × h = 48.0 × 17 = 816.0 (Kg · mm)
U bolt bending stress degree σb = M / Z = 816.0 / 57.7 = 14.14 (Kg / mm ² )
Here, Z in the above equation is a bolt section coefficient, and when the bolt root diameter d1 is 8.376 mm, Z = (π × d1 cube) / 32 = (π × 8.376 cube) / 32 = 57.7 (mm ³ ).
[0026]
U bolt tension T = Ry / 2 = 76.3 / 2 = 38.15 (Kg)
U bolt tensile stress degree σt = βk × (T / A1) = 2.64 × (38.15 / 55.1) = 1.83 (Kg / mm ² )
Here, A1 in the above equation is the cross-sectional area of the U bolt in the threaded portion. If the bolt root diameter d1 is 8.376 mm, A1 = π × (square of d / 4) = π × (8.376 / 2) (Article / ⁴ ) = 55.1 (mm ² ).
U bolt shear stress τ = Rz / A1 = 48.0 / 55.1 = 0.87 (Kg / mm ² )
Synthetic stress degree σm = [square of (σb + σt) + square of 3 × τ] = 16.04 (Kg / mm ² )
[0027]
(2) Stress amplitude during vibration U Bending moment of bolt M = Fz × h = 28.0 × 17 = 476.0 (Kg · mm)
U bolt bending stress degree σb = M / Z = 476.0 / 57.7 = 8.25 (Kg / mm ² )
U bolt tension T = Fy / 2 = 35.0 / 2 = 17.5 (Kg)
[0028]
U bolt tensile stress degree σt = βk × (T / A1) = 2.64 × (17.5 / 55.1) = 0.84 (Kg / mm ² )
U bolt shear stress τ = Fz / A1 = 28.0 / 55.1 = 0.51 (Kg / mm ² )
Synthetic stress degree σm = [square of (σb + σt) + square of 3 × τ] = 9.13 (Kg / mm ² )
[0029]
From the above experimental results, when the support structure according to the present invention shown in FIG. 1 is compared with the conventional support structure shown in FIG. 2, the bending stress degree σb of the U bolt with respect to the pipe reaction force is 8.31 / 14.14 = 0.59 (59%), the shear stress degree τ of the U bolt is 0.61 / 0.87 = 0.7 (70%), and the combined stress degree is 10.19 / 16.04 = 0.63 (63% ).
[0030]
The bending stress σb of the U bolt at the time of vibration is 4.85 / 8.25 = 0.59 (59%), and the shear stress τ of the U bolt is 0.36 / 0.51 = 0.7 (70% ), The resultant stress level is reduced to 5.72 / 9.13 = 0.63 (63%). Therefore, it is clear that the support structure according to the present invention has improved durability since the stress level that causes metal fatigue of the U-bolt is reduced as compared with the conventional support structure.
[0031]
【The invention's effect】
As described above, in the piping support structure according to the present invention, the legs of the U-bolt supporting the piping are inserted into the bolt holes provided in the mounting member, and the U-bolt is the rear end of the threaded portion formed in the leg. Are fastened by nuts without projecting from the bolt holes to the pipe side.
[0032]
According to the present support structure, the rear end of the threaded portion formed on the U bolt does not protrude from the bolt hole toward the pipe side. No threads to reduce are formed. Therefore, the load applied to the leg from the pipe concentrates on the portion where the thread is not formed, and the durability of the leg can be improved. The present support structure is particularly effective when the U-bolt is subjected to continuous high-cycle vibration or continuous shear stress from the pipe.
[Brief description of the drawings]
FIG. 1 is a sectional view of a pipe support structure according to the present invention.
FIG. 2 is a sectional view of a conventional pipe support structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piping 2 Mounting member 3 Bolt hole 4 U bolt 5 Leg 6 Screw 6 a Rear end 7 Nut 8 Lock nut

Claims (4)

The leg 5 of the U-bolt 4 supporting the pipe 1 is inserted into the bolt hole 3 provided in the mounting member 2, and the rear end 6 a of the screw 6 formed in the leg 5 is formed in the bolt hole 3. Characterized by being fastened by a nut 7 so as not to protrude from the pipe 1 side. The pipe support structure according to claim 1, wherein the U bolt (4) is subjected to a continuous high-cycle vibration or a continuous shear stress. The leg 5 of the U-bolt 4 supporting the pipe 1 is inserted into the bolt hole 3 provided in the mounting member 2, and the rear end 6 a of the screw 6 formed on the leg 5 does not project from the bolt hole 3 toward the pipe 1. The method of supporting a pipe, wherein the nut 7 is fastened to the leg 5 of the U-bolt 4 as described above. 4. The pipe supporting method according to claim 3, wherein when the U bolt 4 is fastened with the nut 7, the amount of insertion of the leg 5 into the bolt hole 3 is adjusted by interposing a lock nut 8.

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