JPH0510479A - Pipe clamp - Google Patents

Abstract

PURPOSE:To prevent generation of hoop tightening stress at the time of hot shock by fastening a pipe by two sets of inner and outer bolts of fixing members confronting each other, interposing a collar and an adjusting ring in each group of inner bolt fixing members, and interposing springs for applying tightening force to the pipe by means of the outer bolts. CONSTITUTION:The outer periphery of a pipe 1 is surrounded with a pair of bands 2, and the pipe 1 is fixed by tightening two sets of inner and outer bolts 12, 13 of fixing members 11. Each space between the fixing members 11 is regulated by each collar 15 and each adjusting ring 14 interposed in each inner bolts 12 to set a little gap between the inner surface of each band 2 and the outer surface of the pipe 1. The gap is selected to be larger than the amount of thermal expansion of the pipe 1 at the time of hot shock and smaller than the maximum gap allowed at the time of earthquake. A spring force set within a stress allowed normally for the pipe 1 is applied to the pipe through the fixing member 11 by a disc spring 16 in the outer bolt 13, so that shifting between the pipe 1 and a pipe clamp 10 can be prevented and the hoop tightening stress of the pipe 1 at the time of hot shock and the vibration of the pipe at the time of earthquake can be suppressed suitably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe clamp used for a piping system for high temperature fluid such as fast breeder reactor using liquid metal sodium as a coolant.

[0002]

2. Description of the Related Art A pipe clamp holds a pipe through which a fluid flows. Conventionally, for example, as shown in a front view of FIG. 7 and a side view of FIG.
A pair of bands 2 and reinforcing webs 3 are provided on the outer circumference of the bands 2, and bolts 5 for tightening the pipe 1 through fixing members 4 formed at both ends thereof and a self-weight which is a supporting device of the pipe 1 are supported. And a rib 8 for connecting a vibration isolator 7 having a steadying function at the time of an earthquake. Due to its function, the piping clamp supports the weight of the piping system through a hanger 6 to a building (not shown), and at the time of an earthquake, the vibration isolator 7 prevents the piping system from swaying, and the stress that occurs in the piping system due to its own weight or an earthquake. The pipe 1 and the band 2 are in close contact with each other as much as possible and firmly fixed by the bolt 5. Therefore,
Generally, the outer diameter of the pipe 1 and the inner diameter of the band 2 are manufactured to be substantially the same.

However, the pipe 1 used in the fast breeder reactor is a high-temperature liquid metal in which the fluid flowing is about 500 ° C., and the pipe 1 is covered with a heat insulating material 9 together with a pipe clamp to prevent heat dissipation. Therefore, during steady operation of the plant, the temperatures of the pipe 1 and the pipe clamp are almost the same. However, when the temperature of the flowing coolant suddenly changes due to an abnormality in the plant or the like, the pipe 1 itself follows the temperature of the internal fluid, but the pipe clamp has a large heat capacity, and the heat transfer from the pipe 1 Since a delay also occurs, a temperature difference temporarily occurs between the two. For example, in a plant that uses a high temperature coolant such as a fast breeder reactor with a temperature of up to about 500 ° C, the stress of the piping system due to thermal expansion is large due to the high temperature of the fluid, and the thermal transient stress due to temperature change is also a significant factor. Is. On the other hand, the liquid metal loop of the fast breeder reactor has a low pressure and is operated at a maximum of 10 kg / cm ² G or less. Therefore, the piping is thin and the rigidity of the piping itself is not so high.

[0004]

In the above-mentioned piping system, if a conventional tightening type piping clamp is used, the temperature change occurs in the coolant as described above, and the temperature difference between the piping 1 and the band 2 is caused. In the event of an increase in coolant temperature (hot shock), for example, when the pipe 1 tries to thermally expand, the pipe clamp restricts the movement of the pipe 1 to cause a large rattling stress. There was a problem that was added. As a countermeasure, if the wall thickness of the pipe is increased to increase the mechanical strength of the pipe, the weight of the pipe system is increased, and it becomes necessary to reinforce the support structure and the like. Further, if a gap is provided in advance over the entire circumference between the pipe 1 and the band 2 so that a rattling tightening stress does not occur at the time of a hot shock, the pipe clamp can prevent the vibration isolator 7 from operating during normal operation.
There is a problem in that the function of supporting the pipe 1 at an appropriate position is impaired by causing movement or rotation in the pipe axial direction due to the eccentric load or the vibration load during an earthquake.

The object of the present invention is to provide a space and a spring in the tightening portion of the pipe to support the pipe with an appropriate tightening force, and do not give a squeezing stress during a hot shock of the plant. Another object of the present invention is to provide a pipe clamp that suppresses vibration without causing positional displacement of the pipe even during an earthquake.

[0006]

A band that surrounds a pair of semi-arcuate pipes having a reinforcing web on the outer periphery and fixing members at both ends, and a hanger connected to the fixing member and the band or the reinforcing web are provided. In a pipe clamp consisting of a vibration isolator connected via ribs, the pipe is fastened with two sets of bolts on the inside and outside with respect to the pipe axis provided on the facing fixing member, and the inside bolt fixes the fixing member. A collar for setting an interval and an adjusting ring are inserted, and a spring for applying a tightening force to the pipe is inserted on the outside of the fixing member with an outer bolt.

[0007]

The outer circumference of the pipe is surrounded by a pair of bands, and two sets of bolts on the inside and outside of the fixing member are fastened to fix the pipe. The collar inserted between the inner bolts and the adjusting ring regulate the distance between the fixing members, thereby setting a slight gap between the inner surface of the band and the outer surface of the pipe. This gap is selected to be larger than the amount of thermal expansion expected during a pipe hot shock and smaller than the maximum allowable gap during an earthquake.
Also, with the outer bolt, the spring force set within the stress that the pipe is normally allowed is applied to the pipe through the fixing member, thereby preventing the displacement between the pipe and the pipe clamp,
Appropriately suppress hoop tightening stress on pipes during hot shocks and shake of pipes during earthquakes.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those of the above-described conventional technique are denoted by the same reference numerals and detailed description thereof will be omitted. The piping clamp 10 shown in the front view of FIG.
The pipe 1 is surrounded and gripped by a pair of bands 2 provided with fixing members 11 at both ends. The pipe 1 is opposed to the fixing member 11
Inner bolts provided inside and outside with respect to the pipe axis of
Tightened with 12 and outer bolts 13. A cylindrical adjustment ring 14 and a collar 15 with a collar are inserted between the fixing members 11 of the inner bolt 12, and a plurality of disc springs 16 are inserted on both outer sides of the fixing member 11 in the outer bolt 13. Through. A hanger 6 is attached to the outer bolt 13 and is supported by a building (not shown), and the band 2 or the reinforcing web 3 is attached.
Is provided with a rib 8 for attaching the vibration isolator 7.

The fixing member 11 is formed by bending both ends of the band 2 or by separately welding a flat member. On the other hand, as shown in the side view of FIG. 2, the outer surface of the pipe 1 and the pipe clamp 10 are surrounded by the heat insulating material 9, but the outer bolt 13 and the disc spring 16 are arranged outside the heat insulating material 9. The disc spring 16 is prevented from creeping due to high temperature.

In this embodiment, the support of the pipe 1 is adjusted by the inner bolts 12 between the fixing members 11 as shown in the front view of the fixing members of FIG. 3 and the enlarged front view of the main parts of the fixing members of FIG. Since the ring 14 and the collar 15 are inserted, when the inner bolt 12 is tightened, a gap δ between the fixing member 11, the adjusting ring 14 and the collar 15 is provided between the outer diameter of the pipe 1 and the inner diameter of the band 2.
There is a gap corresponding to ₁ and δ ₂ . On the both outer sides of the fixing member 11 with the outer bolts 13, six disc springs 16 are provided on one side and 12 on both sides.
One piece is mounted to secure the required tightening load and displacement amount h ₀ . Therefore, by tightening both the inner bolt 12 and the outer bolt 13, the pipe 1 uses the band 2 to form the gaps δ ₁ and δ between the fixing member 11 and the adjusting ring 14 and the collar 15.
_In the range of _2, the pipe 1 is held by an appropriate tightening load given by the spring constant of the disc spring 16.

A gap δ ₂ provided inside the fixing member 11
Is defined as the amount of thermal contraction in the radial direction of the pipe 1 during cold shock, and the gap δ ₁ provided outside the fixing member 11 is set in the amount of thermal expansion in the radial direction of the pipe 1 during hot shock. Then, the total amount of clearance δ ₁ and clearance δ ₂ is about ± 2 mm, which is the maximum amount of backlash allowed during an earthquake, totaling about 4
It is set to be within mm. Further, the length l ₁ of the adjusting ring 14 is determined by installing the pipe clamp 10 on the pipe 1 and installing the disc spring 16
The gap δ ₂ is set to a specified value when the specified displacement h ₀ is given to the. Length below collar 15 collar l ₂
Is a total of the plate thickness t of the fixing member 11 and the gap δ ₁ and the gap δ ₂ (l ₂ = t + δ ₁ + δ ₂ ) and is constant. Length l ₁
Adjusts when the pipe clamp 10 is actually attached to the pipe 1, in order to absorb the manufacturing tolerances of the pipe 1 and the pipe clamp 10. Note that this adjustment may be performed by making the adjustment ring 14 short beforehand and inserting a shim as appropriate.

Next, the operation of the above configuration will be described. If the pipe 1 is made of stainless steel with a diameter of 550 mm and a thickness of 10 mm, for example, the tightening load P ₀ is 25
If about 100 kgf is applied, it is possible to sufficiently prevent the displacement of the pipe 1 and the pipe clamp 10, and the stress generated in the pipe is sufficiently within the elastic range. On the other hand, in such piping,
It is sufficient that the gap δ ₁ is about ₂ mm and the gap δ ₂ is about 1 mm, and the gap δ ₁ + δ ₂ <4 mm can be set.

FIG. 5 is a spring constant characteristic diagram of the disc spring, and FIG. 6 is a spring constant characteristic diagram of the pipe clamp. The spring constant of the disc spring 16 and the spring constant characteristic of the entire structure of the pipe clamp 10 are explained. It is a figure. In Fig. 5, when 6 disc springs 16 are arranged in series on both sides and a total of 12 disc springs are arranged in series, a displacement of 10 mm (Δh
₀₎ can be obtained load P ₀ tightened about 2,500 kgf. Therefore, during normal operation, the pipe 1 is gripped by the pipe clamp 10 by the tightening load P _{0 of} about 2500 kgf obtained by the disc spring 16. When hot shock pipe 1 the displacement position Delta] h ₀ at this time based on (+ [delta] ₁₎ and during cold shock (-
It is possible to design δ ₂ ) such that the tightening load of the pipe 1 is P _{1 to} P ₂ and does not differ much from the tightening load P ₀ during normal operation.

Here, the total gap is δ ₁ + δ ₂ = about 3 mm
Therefore, as shown in FIG. 6, when the displacement x of the pipe 1 is 0 and the displacement is within ± 1.5 mm, the spring constant of the pipe clamp 10 is equal to the spring constant of the disc spring 16 (thin line portion). Although it works, when the displacement of the deflection of the pipe 1 becomes larger than this, the fixing member 11 shown in FIG. 4 contacts the adjusting ring 14 and the collar 15. However, the tightening load applied to the pipe 1 at this time is within P _{1 to} P ₂ , the positional displacement with the pipe clamp 10 does not occur, and the stress on the pipe 1 is maintained within the elastic range. After that, the pipe 1 is supported by a large spring constant (thick line portion) synthesized by the system including the pipe clamp 10 and the vibration isolator 7, and the vibration of the pipe 1 can be suppressed by the vibration isolator 7 even during an earthquake. ..

[0015]

As described above, according to the present invention, the rattling tightening stress due to the thermal expansion at the time of hot shock applied to the pipe can be eliminated, and the vibration can be isolated within the allowable gap against the vibration during the earthquake. Is. In addition, the positional displacement between the pipe and the pipe clamp can be prevented even if the heat shrinkage of the pipe during the cold shock is taken into consideration. Further, since the disc spring to be used is installed in a low temperature portion and has a highly reliable design, it is particularly effective in supporting thin-walled pipes that handle high-temperature fluids, and has the effect of improving the reliability of the piping system.

[Brief description of drawings]

FIG. 1 is a front view of a pipe clamp of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a front view of a fixing member of the present invention.

FIG. 4 is an enlarged front view of the main part of the fixing member of the present invention.

FIG. 5 is a spring constant characteristic diagram of a disc spring.

FIG. 6 is a spring constant characteristic diagram of a pipe clamp.

FIG. 7 is a front view of a conventional pipe clamp.

FIG. 8 is a side view of FIG. 7.

[Explanation of symbols] 1 ... Piping, 2 ... Band, 3 ... Reinforcing web, 6 ... Hanger,
7 ... Vibration isolator, 8 ... Rib, 9 ... Heat insulating material, 10 ... Piping clamp, 11 ... Fixing member, 12 ... Inner bolt, 13 ... Outer bolt,
14… Adjustment ring, 15… Color, 16… Disc spring.

Claims (1)

Claim: What is claimed is: 1. A band surrounding a pair of pipes in a semi-arc shape having a reinforcing web on the outer periphery and fixing members on both ends, a hanger connected to the fixing member, and the band or the reinforcing web. In a pipe clamp composed of a vibration isolator connected via ribs, the pipe is fastened with two sets of bolts, an inner bolt and an outer bolt, with respect to the pipe axis provided on the facing fixing member, and the inner bolt fixing member. A pipe clamp characterized in that a collar for setting a gap and an adjusting ring are inserted, and a spring for applying a tightening force to the pipe is inserted outside the fixing member with an outer bolt.